in tfje €itv of JSeio §orfe^c>k>v/? ^cijool of Bcntal anli 0tal ^urgerp i^efetente l^itirarp General Editor. — John D. Comkik M.A.. H.SC. M.l).. K.R.C.P.K, RADIOGRAPHY, X-RAY THERAPEUTICS AND RADIUM THERAPY Volumes already published in this Series TEXT-BOOK OF MIDWIFERY. For Students and Practitioners. By R. W. Johnstone, M.A., F.RC.S., M.R.C.P.E. Crown 8vo, cloth, with 246 Ilkistrations (3 coloured). Price $3.25 DISEASES AND INJURIES OF THE EYE. A T^xt-book for Students and Practitioners. By Wm. George Sym, M.D., F.R.C.S.E. Containing 25 full-page Illustrations, 16 of them in colour, and 88 figures in the text; also a type test card at end of volume. Small crown . 8vo, cloth. Price $2.50 PRACTICAL PATHOLOGY INCLUDING MOR- BID ANATOMY & POST-MORTEM TECHNIQUE. By James Miller, M.D., F.R.C P.E. Crown 8vo. cloth, with 112 Illustrations, the Frontispiece being in colour. Price $2.50 MEDICAL APPLIED ANATOMY. For Students and Practitioners. By T. B. Johnston, M.B. Crown 8vo, cloth, containing 146 Illustrations in the Text and 3 full- page Illustrations in colour. Price $2.50 TUBERCULOSIS OF THE BONES AND JOINTS IN CHILDREN. By John Eraser, M.D., F.R.C. S. (Edin.), Ch.M. Royal 8vo, cloth, containing 51 full-page Plates, 2 of them in colour, and 164 other Illustrations in the Text. Price $4.50 The Macmillan Company New York Digitized by the Internet Archive in 2010 with funding from Open Knowledge Commons http://www.archive.org/details/radiographyxrayOOknox 1. Hahd Condition. . ,r r, r, 4. \ KHY Soft Condition. Note absence of blue gas iu region of anode, ,^^^ j.^.,^^ ,^i,^^ ^j^,^^ ^^^ ^ ^^^^^^^ ^j^^^ .^ also sharply-cut upper limit of green hemisphere. ^^^ p,eceding figure, and the cathode stream is The condition indicates absence oi reverse more evident current. 5. Reverse Current in Circuit. 2. Normal Condition. The appearance of the tube is changed entirely. The hemisphere has lost its sharply-cut appear- Note faint bine cloud in region of anode. ance and is irregular. The faint blue cloud, due Reverse current is practically absent. to gas in the region of the anode, has also changed, and the upper hemisphere of the tube is occupied by irregular rings. o c. rt 6. Polarity Reversed. 3. Soft Condition. T-,.',, ij, • J J- The cathode has become the anode and vice saxnt blue cloud has increased and is novi^ xt t ti, j. c iii, i i r^-u , . , , „, I • 1 • J.-1, versa. Note the stream of gas at the back of the very noticeable. The green hemisphere is still , , i iu -u • -u* ,. ^ ^^ -j. , •^ , . V . J- ,• i. JL 1 i tube and the bright spot on glass wall opposite sharply cut, but a distinct cathode stream , i-. ,■ j.-u i i xt -u / '^ •' , , ' ,, . , -, 1 4.- i.1 1 to the anti-cathode : also the absence of gi'een appears between the catliode and anti-cathode. i, • -u ^^ hemisphere. Appearances of X-Ray Tube in Action. (Reproduced from coloured drawings kindly lent by Mr. C. Andrews.) RADIOGRAPHY X RAY THERAPEUTICS AXD RADIUM THERAPY BY ROBERT KNOX M.D. (Edin.), M.R.C.S. (Eng.), L.R.C.P. (Lond.) HON. RADIOGRAPHER, KINg's COLLEGE HOSPITAL, LONDON DIRECTOR, ELECTRICAL AND RADIOTHERAPEUTIC DEPARTMENT, CANCER HOSPITAL, LONDON HON. RADIOGRAPHER, GREAT NORTHERN CENTRAL HOSPITAL, LONDON CAPTAIN R.A.M.C. (t.) 4t Fig. 15. — Dreadnought interrupter showing detail. A, Container. B, Jet. C, Contact teeth. E, Screw. F, Shaft bearing. H, Oil cups. K, Motor brushes. open for a few moments in order to expel the air. This tap is then closed and the other connected to the gas supply left open, and advantage taken of the pressure from the mains. If there is no handy gas supply a gas bag may be used or ether vapour. The latter may be employed by vaporising a small quantity of methylated ether placed on the top of the mercury and starting the interrupter with a small current before closing the taps. 20 EADIOGEAPHY Fig. 16. — Instanta interrupter. In the Instanta interrupter and others there is an arrangement of four jets so that eight makes and breaks are obtained per revolution, and it is also so arranged that the circuit is broken in two different places at the same moment. This has the ef!ect of greatly increasing the suddenness of the interruption. Sanax Interrupter. — The Sanax interrupter consists of a small steel pear- shaped bowl mounted direct to the axle of an electric-motor and situated perpen- dicularly above the motor. Thus, when the axle of the motor rotates, the pear- shaped bowl is rotated also. Inside the bowl a very small quantity of mercury (only 10 oz. weight) is placed, and, by centrifugal force, travels up the side of the bowl until it finds the extreme peri- phery, where a distinct groove or bed is made to receive it. Thus it will be seen we have a revolving bowl and in it a revolving ring of mercury. Inside the interrupter bowl and carried on a vertical spindle is a fibre disc with two copper segments. This disc is mounted, free to revolve, on ball-bearings top and bottom, and is horizontal in position. It is not placed in the centre of the bowl, but over to one side, so that when the bowl rotates its edge engages with the rotating ring of mercury and is, therefore, of course, revolved by it. The current is led to the metal bowl and to the mercury ring by means of an ordinary terminal, and the current is led also to the segment in the disc by means of the spindle carrying same. Thus, each time one of the copper segments enters into the mercury ring the current is allowed to pass, and each time the segment leaves the mercury ring and the fibre of the disc enters the ring, there is an interruption period. By the unique construction of working two circles together — the mercury ring and the fibre segmented disc — a splitting up of the mercury, such as would occur by plunging into the mercury any other form of con- tact, is completely avoided. As already mentioned, the free revolving fibre disc with two copper segments is placed not in the centre of the bowl, but eccentrically, and can be inserted more or less into the mercury ring from the outside, even if the motor is running. This arrangement makes it possible to put the disc so that it just touches the mercury ring, in which case the duration of contact is very short. The further the disc is put into F:g. 17. Sanax interrupter. INTERRUPTERS—CAUSES OF DEFECTIVE WORKING 21 the mercury ring the further the segment travels in the mercury, and therefore the duration of contact can be extended as desired. Moreover, the number of interruptions is regulated by the speed of the motor by a special volt regulator mounted on the switchboard, so that not only is the duration of contact independent of the number of interruptions, but both are also independent of the primary current. The Di-electric used in the Sanax interrupter is paraffin. Alcohol, gas, and other di-electrics have been tried, but paraffin has given the best results. Before the introduction of the Sanax interrupter the mercury inter- rupters using paraffin as a di-electric, in spite of their numerous advantages, had the great disadvantage of emulsifying the mercury. The cause of this is not the burning of the same by the opening spark but the mechanical breaking up and churning of it with the di-electric. After working the mercury interrupter for a short time it was imperative to remove the dirty mercury and to clean it — a very disagreeable and troublesome proceeding. The ingenious principle of the Sanax interrupter — the working together of the two circles in unison and the continuous centrifugal rotation — delays the emulsification of mercury. In consequence of its greater specific weight the mercury is always driven to the farthest outside point and disintegrates by itself all the fighter substances, therefore remaining for a longer or shorter time, according to the amount of usage, clean at the point of interruption. The Number of Interncptions can be increased up to about 12,000 per minute. By means of a turning switch on the switchboard the motor can be run fast or slow, and further, by means of a resistance, it is possible to run the motor at any desired speed, thus obtaining any number of interruptions. Causes of Defective Working. — A few short hints on the causes of defective working may be of assistance to workers. If when switching on the motor it does not start up, the speed regulator should be at once cut out, and then the motor having started, it can be brought back to the position of usual working. There also may be an interruption or short circuit in the main cable leading to the switchboard or table, or the cables leading to the motor of the inter- rupter may have become loosened, or the brushes and their screws may have become loose, all of which faults would be indicated by the motor refusing to start. If the commutator starts to spark after running some fcime it will be found that this is generally due to oil and carbon dust, and this must be removed by cleaning the commutator with fine emery cloth, and also cleaning the carbon brushes. If when the coil is now switched on we observe no fight in the X-ray tube, this may be due to the fuse having been burnt through or become loosened. Great care must be taken to see that all bearing contacts are clean, that all cables are perfect, and that all terminals are absolutely secure. Should the tube give an unsteady fluorescence this may be due to some extent to the vacuum of the tube, and can be controlled somewhat by adjust- ing the interrupter. If the tube flickers with a contact of a certain size. 22 RADIOGEAPHY the tube may be steadied by increasing this contact. This flickering may be also due to the motor of the interrupter running slowly. Another reason for this efiect in the tube may be the piercing of the condenser, and this can be detected by testing the spark length of the coil. If one cannot obtain the full spark length and the primary current is above the normal, then the condenser should be carefully examined. Finally the copper contacts of all interrupters need replacing from time to time, as they become burnt through from long usage, this leading to bad and intermittent working. Improved Mackenzie Davidson Interrupter. — This is a useful form of mercury interrupter when an outfit of moderate capacity is all that is required, and when accumulators are used as the source of supply. It consists of a metal pot containing a supply of mercury into which a contact set at an angle dips. This contact is mounted on the end of the Fig. 18. — Improved Mackenzie Davidson interrupter. (Scliall shaft of a motor whose speed can be varied in order to vary the number of interruptions. This interrupter requires rather more mercury than most of the other types. Electrolytic Interrupter. — This type was introduced by Professor Wehnelt. The principle of construction is simple. A platinum wire and a large lead electrode are immersed in diluted sulphuric acid in the proportion of acid 1 oz. to 5 oz. of water. This interrupter is without doubt a good one, far exceeding the best mercury interrupters, not only in regard to output and capacity for regula- tion, but also in simplicity of construction and use, as well as in safety of working. Wehnelt interrupters can be used wherever continuous current is supplied direct, i.e. from supply mains, accumulators (at least about 65 volts), or a motor generator, or where single-phase or three-phase current is converted into continuous current by means of rotary converters or ELECTROLYTIC INTERRUPTERS 23 electrolytic valves. As all metals, with the exception of platinum, when used for the active electrode, even if the polarity is correct, are rapidly con- ^.^S^S Fig. 19. — Single-poiut electrolytic interrupter. (Siemens.) a, Glass vessel. b, Porcelain diaphragm. c, Adjustable ebonite collar. d, Terminal. e. Lead electrode. Fig. 20. — Three-point electrolytic interrupter. (Siemens. ) Fig. 21. — Single-point electro- lytic interrupter. (Watson.) The upper part of the inter- rupter has attached to it a solenoid which is couuected electrically to the switch-table, allowing of the control of the depth of point in the fluid. Fig. 22. — Trolley control table, with resistances arranged to facilitate time and rapid exposures. (Siemens.) sumed, platinum is always used with these interrupters as the active electrode, because it disintegrates very slowly and therefore gives the best results. 24 RADIOGEAPHY These interrupters are manufactured with 1, 2, 3, 4, or 6 separate electrodes, i.e. they are used as single, double, triple, quadruple, or sextuple interrupters. When employing a multiple interrupter one is not obliged to regulate at the interrupter itself, and can therefore set it up outside the X-ray room, so that its noise causes no disturbance. Fig. 23. — Larger view of top of trolley control table to show the regulating parts. (Siemens.) The advantages of the Wehnelt interrupter are summarised briefly as follows : (1) SimpUcity of construction. (2) Convenient handling of the X-ray outfit. The Wehnelt interrupter requires no attention. (3) Largestlcapacity, as it interrupts very rapidly the largest amount of energy and therefore the most intense X-rays are obtained. (4) Long life to the tubes even when used with heavy currents. (5) In comparison with all mechanical interrupters, great reliability. METHOD OF ACTION OF AN ELECTROLYTIC INTERRUPTER 25 This is due to its simplicity of "construction and method of working, the absence of moving parts, and the consequent simplicity of connections of the whole outfit. In the case of X-ray outfits for rapid exposures three or more electrodes are arranged in parallel by means of a switch, and the electrodes are so adjusted that equal parts of them interrupt the total current. In conjunction with a time-relay switch these interrupters can be used to obtain exposures of from -j\y to 6 seconds in connection with an automatic cut-out switch. Such a device is illustrated opposite. With the most power- ful induction coil outfit, such as the single-impulse apparatus constructed for use with the electrolytic interrupter, a time-relay should always be included, along with a triple electrolytic break, for then we have a large range of exposures at our command. Method of Action of an Electrolytic Interpupter. — AVhen a current of at least 50 volts and 5 amperes is passing through the interrupter in such a manner that the platinum is the anode, the density of the current is so great near the small anode that it becomes very hot and steam is formed. In addition, electrolysis causes hydrogen and oxygen to appear, and these gases form an insulating mantle round the anode which inter- rupts the current. If there is a sufficient amount of self-induction m the circuit, a spark appears at the breaking point, namely the anode, ignites the gases, and the explosion gives the acid access to the platinum, thus closing the current again. This process takes place with extraordinary rapidity and regularity. The intensity of the discharges and the frequency of the interruptions can be varied in the widest limits by varying the electro-motive force used in the primary circuit, the surface of the platinum anode, and the amount of self-induction. The disadvantage of the electrolytic interrupter is the great care that has to be exercised in its use. Unless a considerable latitude is allowed for, the X-ray tube is more likely to be damaged, the anti-cathode being quickly pierced if too powerful currents are used for long periods. When, however, the electrolytic interrupter is provided with three or more points and a suit- able switch on the general or main switchboard, all degrees of exposure can be successfully used. Even for therapeutic work this interrupter when properly used is undoubtedly one of the best forms of interrupter. With a time-relay switch most powerful currents may be used if only for a fraction of a second. Carelessness in leaving the thicker points in the circuit and then using it for prolonged screening will almost invariably ruin a tube. A single-point electrolytic interrupter can be controlled from a distant point by means of a solenoid. In this way it is possible to vary the depth of the platinum point in the acid solution and so vary the intensity of the current passing through the interrupter. This is a most useful addition to the electrolytic interrupter. Interrupters for Alternating" Currents. — These are numerous. 26 RADIOGRAPHY meclianical and chemical, and enable us to use the alternating current without rectification. Good though some of these are, none is so efl&cient as an interrupter on a continuous current circuit, and the maximum intensity which can be reached even with the best alternating current interrupter is much less than that obtainable with a continuous current. When the alternating supply has a higher periodicity than sixty it is better to rectify the current by installing a motor transformer. With a periodicity of less than sixty the best interrupter to use is that made by Gaifie of Paris. This interrupter and a Gaiffe Rochefort transformer or coil may be used for therapeutic work by utilising less of the break, but Fig. 24. — Gaiflfe interrupter. V, Vessel. e, e, Screws. I^, I^ N, Terminals. M, Vulcanite cap. B, Impulse. P, Handle. R, Inlet tap. R\ Outlet tap. C, Cone. b, b, Orifices. d, d, Di, D2, Teeth, when required for radiography the intense current is used. This is done by a mechanical contrivance which throws all the teeth in the interrupter into action. Quite rapid exposures may be obtained with this apparatus especially if intensifying screens are used. The mercury jet is caused, as in some of the previous interrupters, by the rotation of a cone with its lower end in mercury, and by centrifugal force the mercury is jetted out against the stationary contacts. The motor part difiers from the continuous current interrupter. The break is started with a smart twist of the milled head on top and the needle of the milli- ammeter watched until this is steady, this indicating that the interrupter is in synchronism with the supply. Some operators can judge of this by sound. At first there is a grating sound, and this becomes smooth when synchronism is attained. ESSENTIALS FOR THE PRODUCTION OF X-RAYS 27 The essentials for the production of X-rays are : (a) A supply of electric energy ; (6) a means of transforming a current of low tension into one of high tension ; (c) an interrupter ; (d) an X-ray bulb. The apparatus employed may vary from the simplest to the most highly complicated. Its selection and arrangement will depend upon the operator and the resources at his command. Complicated and expensive apparatus is not absolutely essential to ensure the production of good nega- tives. The most important point of all is for the operator to make the most of the apparatus at his disposal. When he grasps the underlying principles of the necessary apparatus, and particularly of the technique of radiography, he may venture to add to his outfit those items which are extremely useful but not absolutely necessary. A thorough understanding of the mechanical parts of the installation is of great value to the radiographer, but is not absolutely necessary, because it is generally possible to obtain help in the manipulation of the apparatus. But a thorough knowledge of the X-ray tube is of the utmost importance, because it is always the ruling factor in radiography and therapeutics. In order to produce the best quaUty of X- rays for a specific purpose in either radiography or therapeutics it is necessary to have accessory apparatus which enables the operator not only to control the X-ray tube but to reproduce at will conditions which are known to lead to the production of good results. The accessory apparatus is therefore a most important part of the equipment, and must be considered in detail. In the whole organisation of an X-ray outfit the most important point is to have a good X-ray tube under perfect control, then work becomes easy and good results follow. In view of the importance of this subject the following pages are devoted to a fairly full account of the manufacture of an X-ray tube and the apparatus necessary to enable the operator to exercise an efhcient control over it. X-RAY TUBES AND THEIR ACCESSORIES The Focus Tube This being always the ruling factor in radiographic work, a complete knowledge of its construction and method of working is a sine qua non in the routine work. Should it not be in proper order the best type of apparatus is quite useless as a producer of good radiographs. 1'he quality of the focus tube is all important for success in X-ray work, Anticathode Terminal. Anticathode supporting tube. Junction of anticathode support and bulb. Anode Terminal. Anode Exhaust Point. Glass Mantle. Dark Hemisphere. Anticathode. Target Regulator Tube. Active Hemisphere- Cathode Stream. Cathode. Cathode stem. Regulating Arm. Cathode Terminal. Fig. 25. — Diagram of an X-ray tube with parts named, showing the paths of the cathode stream from the cathode impinging on the anti-cathode ; the active hemisphere shows the paths of most of the X-rays generated. (Watson). as if the tube is unsuitable in that it is too hard or too soft, it is impossible to get good results. If, on the other hand, the tube is in good order good results may be obtained with quite ordinary apparatus. Tubes deteriorate with use, but, carefully handled, they will outlast hundreds of exposures, and show very little sign of damage. The all-essential point is to know how to use the focus tube, and it is 28 DESCRIPTION OF MANUFACTURE OF THE X-RAY TUBE 29 also a great advantage to familiarise one's self with the names of the various parts. Description of the Manufacture of an X-Ray Tube. — The first process consists of the blowing of a glass sphere of the desired capacity with a " neck," which varies from one to two inches diameter, according to the size and type of the tube. The thickness of the walls of the bulb is from '2 to "6 mm. The various metal parts, or electrodes, having been carefully cleaned, are introduced through this neck, and are in turn sealed into position by the glass-blower. Connections are made to the outside by fusing into the glass pieces of platinum wire, and as each portion of the tube is finished, it is annealed with extraordinary care. This annealing is one of the most im- portant processes, as an X-ray tube has to withstand the most intense heat. Fig. 26. — Radiator tube constructed for heavy discharges. (Cossar. ) to say nothing of the rough usage which it may encounter if it is destined for a hospital career. The electrodes having been placed in position, and the regulators, etc., attached, a length of glass tubing is fused on, and the tube is placed on the vacuum pump. The final stages of exhaustion are sometimes very pro- longed, varying according to the size of the tube and the nature of the electrodes employed. A large tube may occupy a considerable time in actual exhaustion. During the process various conditions have to be observed, and it is during pumping that the rmavoidable risks of tube-making are greatest, as with the increase of pressure from without, any stress, flaw, or other fault may result in the sudden collapse of the tube. When exhaustion is complete, the tube is taken from the pump, sealed, tested, and, if found to be in order, is finished oi! with the necessary terminals. The Anti-cathode. — The most important part of an X-ray tube is the anti-cathode, since it is here that the heat is generated, and most dis- 30 KADIOGEAPHY turbances take place. It is this part of the tube which is exposed to the intense force of the cathode stream. The power of resistance to this stream, and the physical effect thereof, possessed by the anti-cathode of the tube is the determining factor in the life of the X-ray tube, and the degree of current it will stand determines largely the amount of work it is capable of performing. Naturally the anti- cathode varies with each tube, and these are now made for special pur- poses. A careful study of the various types of anti -cathode in use will be necessary before the operator can thoroughly understand the best conditions under which the tube will work. The anti-cathodes of some tubes may become incandescent when the tube is running at full cur- rent, and a careful watch is necessary when using tubes in / this way. / The cheaper tubes are made / with light anti -cathodes. The / next class of anti-cathode is that / known as the " heavy anode," consisting usually of a copper tube or sleeve of varying thick- FiG. 27.— Cyclops radiator tube. (C.Andrews.) ness and leng-fch, and carrying The heat generated at the anti-cathode is absorbed and q^j^ j-^g extremity a platinum- radiated along a solid copper rod which is arranged ,11, • -i . -i . i to lacilitatereadyremoval from the tube. When the COated plate Similar tO that USed copper is heated it may be removed and a second [^ ^Jj^g light auodc tubc. In this one introduced. By changing these during an ex- ' posure, the tube can be kept comparatively cool for Case, hOWever, these VariOUS long periods, the vacimm of the t^ibe being thereby jj^etals are Welded together iuto maintained at a constant degree of hardness. . ^ . one contmuous whole, wnicn is supported on a glass sleeve projecting from the wall of the tube. Natur- ally this mass of metal has much greater absorption and conductive capacity than the Hght anode, and will in consequence stand a much greater degree of heating, i.e. a higher current. There is also a proportionately large reserve of gas in these armatures, and, unless grossly over-run, such tubes do not become red-hot, and are therefore much more constant in vacuum. As the weight of metal in the anti-cathode is increased, so (other condi- tions being equal) the capacity of the tube to withstand a high current is increased also. Occasionally, the metal sleeve of the anti-cathode is greatly extended, and is carried directly to the exterior of the tube, terminating / WATER-COOLED TUBE sometimes in a radiating device in order to discharge the heat as expeditiously as possible. As the difficulties which arise in heavy currents for X-ray work are almost wholly concerned with such heating, several other methods have been adopted in order to deal with it in an efficient manner. One is the system on which the Cyclops tube is worked. The other is that employed in water- cooled models. These are described at some length in the following pages. Water-cooled Tubes.— The general use of X-ray tubes cooled by means of water was, for all prac- tical purposes, commenced by the continental radiographers. The original Miiller water- cooled tube is designed mainly on the lines suggested by Professor Walter. It is arranged in the following manner : In place of the usual heavy metal anti - cathode, a solid platinum vessel is provided, and on to the bottom surface of this is fixed a metal plate which is in turn faced with platinum. The upper or open end of the vessel is sealed on to a glass sieve, which is in turn attached to the wall of the tube, and which is expanded, outside the tube, into a reservoir or water chamber approximately 3 inches diameter. When water is filled in, it passes down the glass sleeve to the platinum vessel, and is thus brought into actual contact with the back of the target. This latter feature is an essential in the construction of a water-cooled tube. Workers are strongly advised not to purchase so-called water-cooled tubes when the water does not reach right down to the back of the target, as such instruments simply omit the vital principle which renders the water-cooled tube so highly efficient. When the heat is generated by the impact on the target it is immediately imparted to the water, and the temperature of the target can therefore only momentarily exceed that of boiling water — 100° C. Apart from the efficiency of the cooling system, the construction of water-cooled tubes renders them more satisfactory in other respects. In the first place it is possible to make the anti-cathode almost entirely of platinum, which means that there is practically no metal in the tube likely to give rise to violent changes of vacuum. The water-cooled tubes remain Fig. 28. -Water-cooled tube arranged for overhead work. (C.Andrews.) 32 EADIOGEAPHY therefore at approximately the same degree of hardness for very long periods. The great advantage in this respect cannot be over-estimated, and will appeal both to those who are doing continuous radiographic work, and to those running tubes for long periods for therapeutic purposes. The latter point is of extreme importance for deep therapeutics. The employment of water as a cooling medium is free from all objection, even from that of extra trouble in manipulation ; for if tubes, when not actually running, are stored in one of the excellent vertical holders now on the market, it is not necessary even to empty the water bulb after use, and the only extra attention entailed is the occasional replacing of the water which may be lost by evaporation. The principal feature of water-cooled tubes is that they may be kept in continual use for hours, without any danger of over-heating and consequent X./ Fig. 29. — Water-cooled tube for overhead or under the couch work, showing mica and carbon regulator. (C. Andrews.) softening. Further, they will withstand a much larger current than the ordinary tube will take, and in fact the heavier models will for a short time stand up against the maximum amount of current which can be forced through them. Selection. — In selecting a water-cooled tube, regard must be paid to the class of work which is intended to be done. It must be considered whether the tube is to be used with light or heavy currents, and whether it is to be used only above the couch (either horizontally or vertically), or whether it is desired that it may be used in the horizontal position from below the couch. The tubes for use below the couch are made with the anti-cathode set in the long axis, and are furnished with a curved revolving tube, by means of which the water is prevented from flowing out. The tubes for use in positions other than below the couch have the anti-cathode set at an angle of 45° to the long axis. Tubes for use with heavier currents are made on an exactly similar THE USE OF WATER-COOLED TUBES 33 system to the lighter models, but differ in that the armatures are strengthened in order to permit of the heavier loads being carried. The most important modification is in the anti-cathode, which is made in the following way : The platinum-faced target is set on a massive block of specially alloyed copper, which is in turn attached to a solid platinum vessel similar to that used for the lighter models. By the interposition of this buffer of alloy the capacity of the tube is enormously increased, and at the same time the amount of extra metal thus introduced is not sufficient to rob the tube of its excellent qualities of constancy and steady working. In fact the whole proportioning and " balance " of these tubes has been worked out with a nice exactness which has been amply justified by the result. The Use of Water-cooled Tubes. — It must be remembered that this type of tube is designed and constructed to work with a water-jacket, and it must on no account be used without the receptacle having been filled to within about half an inch of the top. In the case of the pattern for use above and below the patient, the opening of the curved tube should be just above the surface of the water, when the instrument is placed horizontally, thus allowing an outlet for steam. If the tube should be inadvertently worked without water, it must be allowed to cool completely down (say, for at least an hour) before water is filled in. If this precaution is not observed, a breakage will in all probability occur. As stated above, it is not necessary to remove the water after using, and, therefore, there should be little danger of the tube being worked without the cooling medium. Ordinary tap water should be employed, not distilled nor filtered. Should the tube have been running continuously so that the water is boiling, it is permissible to renew the supply, and this may be done without disturbing the tube, by means of a syphon. By placing a vessel containing water at a lower level than the tube and starting the flow by suction, the water may be run out until only about 3 inches of the water-tube remain filled. The container is then raised to a level above the tube, and water allowed to flow in. If no syphon is obtainable, an alternative method is the following : Pour the boiling water out of the tube into a jug, and add cold water in sufficient quantity to render the whole just distinctly warm to the touch. Then refill the water-chamber with the slightly-warmed water. Obviously, if the boiling water were removed, and cold water filled in, the glass might possibly fracture ; but by adopting the above method the supply may be safely renewed. The tube may then be run as before. In cases where the tubes are used in a horizontal position, care should be taken to raise the water-chamber slightly above the level of the anti- cathode itself, so as to keep the water against the target. This prevents the water flowing away from the anti-cathode, as it might do if the tube were absolutely horizontal, and also allows of the escape of bubbles, etc. The curved tube in the cap may be revolved according to the position of the X-ray tube, so as to permit of the aperture being always uppermost. If desired, the water can be circulated through the tube by means of the 3 34 EADIOGEAPHY syphon mentioned above. This is very efficacious, but necessary only when very lengthy runs are being undertaken. There is another type of tube made by several makers which is very efficient and convenient for treatment. This tube has a diameter of about 5 inches (125 mm.). As will be seen from Fig. 215, p. 295, an auxiliary bulb (having a diameter of about 6| inches) is connected to the tube, thus forming a reserve air-chamber. This construction results in the tube possessing all the advantages inseparable from one having a large cubic capacity ; while the fact of the anti-cathode being only 2| inches from the wall of the tube enables the original Sabouraud distance to be adopted. Air-cooled Tube. — -The tube employed is specially constructed, an air pump being employed to supply a forced draught which is sent Fig. 30. — Dessneur tabe with atomiser for cooling the anti-cathode. (Siemens.) This tube is specially exhausted for deep therapeutic work. into the cathode and anti-cathode of the tube. By means of the small electric motor operating the force-pump, air at the temperature of the room is used at considerable pressure. The special modifications of the tube required are as follows : In place of the ordinary cathode there is employed a very massive hollow armature, with the same diameter as the anti-cathode ; into both cathode and anti-cathode are fitted inlet tubes, which bring the cold air into direct contact with the whole inner surface of the armature, and the heated air is expelled through a number of peripheral apertures. The connection between the X-ray tube and the air pump is made by means of strong uidia-rubber tubes. The cathode is cooled as efficiently as the anti-cathode, this being a very important point. In a tube of this type, currents of at least 5 to 7 milliamperes may be passed continuously without any ill ejSects. There has been introduced a further elaboration of this type of tube, i.e. a tube working as described above but fitted in addition with an atomiser connected to a vessel containing water. Instead, therefore, of air being THE GUNDELACH TUBE 35 pumped on the back of the anti-cathode the water is continuously sprayed on the latter and thus cools the electrodes. Fig. 31. — Heavy anode tube (Gundelach). Osmosis regulator. (Siemens.) Gundelach Tube. — The tube figured above is the ordinary Gundelach tube with Osmosis regulator. There has just been introduced a new tube by Gundelach which appears to possess some special advantages for deep therapeutic work. It is not of the usual outward form but cone-shaped, with the anti-cathode near the point of the cone and the terminals and regulator at the base, so that the tube can be brought very near to the part to be irradiated, and at the same time the high-tension terminals are some distance away. Further, the tube is made to be used in a specially thick lead-glass shield with a celluloid window, and on the outside of the window is an arrangement for attaching aluminium filters of various thicknesses. The tube is arranged for air-cooling by means of a forced air-pump, and two feeding tubes from the pump are arranged so that one is connected to the pipe leading to the back of the anti-cathode, and the other to the inside of the protective lead-glass shield in order to keep the outside of the tube cool. The pump connections are worthy of notice, the particular feature being that the air is fed from the pump to a water-cooling chamber, which is essential for successful cooling, otherwise it will be found that the air, after the pump has been running for some time, becomes warm, but after passing through the cooler it is reduced to the temperature of the room, and will remain at this temperature for hours without changing the water. With such a tube and air-pump combination it is possible to work for con- siderable periods with large milliamperages. Coolidg'e Tube. — At the time of writing this book an announcement comes from America of a tube which has been invented by D. D. Coolidge, which appears to be of such novel construction as to make it the greatest advance that has taken place since the discovery of X-rays. The tube is devised to be entirely free of gas and has a vacuum 1000 times greater than the ordinary tube, so that it is impossible to pass a current through it in the ordinary way even with the most powerful apparatus. The anti-cathode is constructed of tungsten, and the cathode, instead of 36 RADIOGKAPHY being an aluminium cup-shaped electrode, consists of a spiral of tungsten wire surrounded by a sleeve of molybdenum to focus the cathode stream. Connected to the cathode spiral is an auxiliary source of current consisting of a small accumulator battery with an ammeter in circuit (it is important that the battery is well insulated from earth), which heats the metal, causing it to give of? a stream of negatively- charged electrons which are projected on to the anti-cathode. The number of freed electrons from the anti-cathode is regulated by the degree of heating of the tungsten spiral, and the speed of the cathode Fig. 32. — Coolidge X-ray tube. (British Thomson Houston. ) stream, upon which depends the penetrating power of the X-rays, is regulated by increasing or diminishing the potential at the terminals of the tube. It is claimed, therefore, that this tube will give us accuracy of adjust- ment, stability of hardness, possibility of exact duplication of results, un- limited life, great range of flexibility, absence of inverse radiation, and extremely large output. The chief feature seems to be that one can at will Fig. 33. — Diagram of Coolidge tube. have any degree of hardness, and any quantity of rays, and these two factors constant for indefinite periods, and can also repeat the same conditions at any time. The most remarkable and valuable advantage is that indicated by its immense output for deep therapeutic work, and also for instantaneous radiography. There is one note of warning, and that is that this tube gives Httle or no visible sign of fluorescence, so that extra precautions must be taken ; otherwise, owing to its much greater output, a serious burn can be produced, the margin of safety being practically nil, whereas one cannot run the ordinary form of tube continuously with a heavy current. Connections. — The accompanying illustration shows the tube properly connected to the storage battery and the terminals from the coils. It must always be home in mind that the entire battery circuit is brought to the full THE COOLIDGE TUBE 37 potential of the tube, and that it', therefore, has to he as thoroughly insulated both from the patient and the ground as has the tube itself. The full circuit is shown in Fig. 35, in which S is the parallel spark gap, M the milhammeter, B the storage battery, E the rheostat for controlling the current in the filament circuit, and A an ammeter for measuring this current. (A is not shown in the illustration. It is a con- venience and not a necessity.) As the diagram shows, the resistance is all in, and hence the filament temperature is lowest when the rheostat handle is pushed as far as possible away from the operator. If the polarity of the machine is wrong, it will be shown by the fact that the milliammeter will register no current, regardless of how high the filament temperature may be. Fig. 34.— Complete Coolidge X-ii, (B.T.H.) ;piin-ia ill |jo.^ition. The Battery.~A convenient size is a 5 or 6 cell (10 or 12 volt) 40 am- pere-hour battery, and it will be found much more satisfactory if arrange- ments are made so that the battery can be connected either every night or else whenever not in use during the day, to the charging circuit. In some cases it will be found convenient to have the battery stand on the floor, while in others it may advan- tageously be placed higher up on a shelf. In the latter case it will be necessary to re-locate the rheostat on the back of the stand, so that the . handle will point in the right direction. Both the rheostat handle and the cord attached to the pull switch (m the battery circuit) should be brought through the lead screen which protects the operator, and to a point within easy and con- vement reach. Fig. 35.— Diagram of connections for Coolidge tube. 38 EADIOGRAPHY Method of Operating. — The technique of various operators and the sources of excitation vary so much that it is difficult to make very detailed suggestions. The following general considerations, however, may be of value. The higher the filament temperature, the greater the discharge current. The higher the voltage backed up by the tube, the higher the penetration. A simple method for starting radiographic work with the tube is as follows : Take a case, for example, where the operator has been setting his rheostat on the 10th button, and adjusting his tube to where it then draws 30 milhamperes. In this case, all that is necessary, with the Coohdge tube, is to set the rheostat on the 10th button, light up the filament in the tube, having the handle pushed as far away as possible, close the main switch, and pull on the rheostat handle until the tube is drawing 30 milliamperes. The main switch is then opened, and the operator is ready to make liis exposure. In other cases, the radiographer will be accustomed to adjust the tube by means of the milliammeter and the parallel spark-gap. This procedure can be applied equally well to the Coolidge tube, and will naturally be the one first used in all cases where the operator is not familiar with his machine. KnoAving that he wants, for example, 20 milliamperes and a 5-inch parallel- gap, he will start with the battery rheostat handle pushed well away from him, and with his main rheostat set on a low button. He will then pull on the battery rheostat handle, and run up to higher buttons on the main rheostat, until the tube is drawing 20 milliamperes and backing up the 5-inch gap. The tube may be safely run with the target at white heat. If excessively high energy inputs are employed, the tungsten at the focal spot melts and volatihses. This results in a sudden lowering of the tube resistance and in blackening of the bulb. The instabihty in resistance disappears instantly upon lowering the energy input, and no harm has been done to the tube, that is, unless it is to be used for the production of the most penetrating rays which it is capable of emitting. In this case, a heavy metal deposit on the bulb is undesirable, as it interferes with smooth running at such high voltages. The tube should not be run with voltages higher than that corresponding to a 10-inch spark-gap between points (that is, it should not be made to back up more than a 10-inch parallel-gap). For long-continued running in an enclosed space and with heavy energy inputs, it will be necessary to provide some means of coohng the glass, as by a small fan or blower. The glass can, however, safely be allowed to get very hot. It is all right so long as it does not soften and draw in. In running the tube on a coil, a valve tube should be used when heavy energy inputs are to be employed. So long, however, as the temperature of the focal spot is not made to approximate that of the cathode, the tube will satisfactorily rectify its own current. There are tubes made in America which differ from the types usually THE PRODUCTION OF X-RAYS 39 made on the Continent and in England, in that they are exhausted by a special process, and as no mercury is employed in the pumping it is impossible for mercury vapours to find their way into the tube ; this enables the tube to be exhausted " hard " in the first instance. The tube is hard from the beginning, and does not therefore require to be carefully worked up for radiographic or therapeutic work. It may be used at once for deep work. The tube may require to be regulated if it is too hard. These new tubes are fitted with a special form of cathode, which prevents the concentration of heat at the neck of the cathode. They are consequently not so Kable to break down when overloaded. The evolution of this type of tube in America is no doubt due to the fact that workers there are using more powerful apparatus for X-ray work, and have had to produce a tube which will stand up to the heavy currents generated by such apparatus. The Production of X-Rays. — When a current of electricity from an induction coil is passed through an X-ray tube, a beam of cathode rays from the concave cathode is focussed on the target or anti-cathode, the surface of which is inclined at an angle of 45° to the rays. The anti-cathode islusually made of a metal of high atomic weight, such as platinum, tungsten, etc. The anode and cathode are usually of aluminium ; from the point of contact of the cathode stream on the anti -cathode, X-rays are given out in all directions. X-rays are invisible, and do not make glass fluorescent. The pale-green hemisphere of fluorescence on the bulb is due to reflected cathode rays from the anti-cathode striking the glass of the tube. This may be clearly shown by the action of a magnet on the boundary of the fluorescence. X-rays are not deflected by the proximity of a magnetic field. The pressure of the gas in an X-ray tube becomes lower with use, and a device for softening the tube {i.e. raising the pressure of the gas in the bulb) is therefore usually provided. The higher the pressure the less is the potential required to work the tube, and the less the penetration of the rays. The X-rays produced and the condition of the tube are termed " soft " if the pressure of gas in the bulb is high. The lower the pressure the harder are the rays. The cathode of the tube is made of aluminium, and is fixed just within the neck of a side tube to the bulb ; it is concave. As the exhaustion of the tube proceeds, the focus of the rays recedes farther and farther from the cathode, and may reach a distance of something like four or five times the radius of curvature of the cathode. The relative positions of cathode and anti-cathode is a matter of experi- ence with the maker. The anti-cathode is usually mounted a Uttle out of focus to avoid its early destruction by fusion, the result of the extreme heat generated at the focus point. When sharp radiographic work has to be done the focus must be exceedingly sharp. Some makers turn out tubes with a very sharp focus, and excellent radiographs are obtained with such tubes. The drawback to the tubes is the comparatively short time they last. The Anti-cathode of the X-ray Tube. — The requirements of an anti- cathode intended for modern radiographic work are : 40 KADIOGEAPHY (1) A high atomic weight to secure a large quantity of rays. (2) A high melting point to permit sharp focussing. (3) A high thermal conductivity. Appearance of the X-Ray Tube in Action. — ^^^^hen the X-ray tube is connected properly one-half of the tube between the cathode and anti- FiG. 36. — Connections of the X-ray tnbe to the FiG. 37. — Connections of the X-ray tube to the coil, showing the route travelled by the coil, showing the apj^earance when the poles spark when the point is the positive pole are reversed. and the negative the plate. cathode looks as if it were evenly filled with green light, the other half of the tube behind the anti-cathode remaining dark, because the anti-cathode acts as a screen. If wrongly connected there is an irregularly patchy fluorescence of the ^^ walls of the tube, and rays appear at intervals which change con- siderably according to the amount of current passing through the tubes. For the appearance of the X-ray tube when correctly and incorrectly in operation, see the coloured frontispiece. The important thing to re- member is first of all to ascertain the polarity of the coil. This is done by testing with the spark- gap. Selection and Regulation of X-Ray Tubes. — Little need be said on this point. As nearly all the tubes on the market are now good, the particular type selected depends to a large extent upon the operator. When possible a number of good tubes should be kept in constant use. A tube which is in good condition and has a sharp focus should be reserved for radio- graphic work ; for therapeutics a tube with a diffused focus is better than a sharp one because it will last longer. This requires to be taken with reserve. Some workers prefer to use a sharp focus for therapeutic work. It may be that the sharp focus of the cathode stream upon the anti-cathode may generate a beam of X-rays of particularly good therapeutic value. Unless for special purposes it is always better to purchase tubes of a medium vacuum, inclining towards the soft side. A tube of large diameter. Fig. 38. — Connection of X-ray tube to the coil, showing coil and connections to tube. A valve tube is inserted on the negative j)ole. SELECTION AND KEGULATION OF X-RAY TUBES 41 7 or 8 inches, will continue to keep good vacuum longer than a smaller tube. For heavy currents, either in radiographic or therapeutic work, the larger tube will in the end be found most economical. The chief advantage of having several tubes in use is that the very soft tube may be used for short exposures and gradually worked up for thicker parts. Then with about half a dozen tubes all parts oi the body may be radio- graphed with a tube in proper condition for the part. New tubes are gener- ally soft and require to be gradually worked up in hardness before they can be used for the deeper parts of the body. It is a good plan to reserve new tubes for short exposures of the thinner parts such as the hands, ankles, etc. After a few weeks of such work a new tube may then be used for the knees, shoulders, and elbows. Later, when the tube has become seasoned, it can be used for the longer exposures required for radiography of the kidney areas, spine, and skull. A new tube should never be overrun, that is, long exposure with large currents should not be used, because if they are, the vacuum may be hope- lessly reduced, and the tube will then require to be re-exhausted. Once a tube is seasoned it will maintain its vacuum and degree of hardness for long periods, and may be used for hours daily. The amount of usage to be got from a tube which has been thoroughly seasoned is surprismg. Sometimes a tube after repeated short exposure may not harden. A good plan is to run such a tube for half an hour to one hour on the minimum current available. A | milliampere through a tube for several runs of that duration may succeed in bringing it into a working condition. It should be treated carefully for several weeks. The majority of tubes after prolonged use tend to harden. This natural hardening from use may be combated in several ways. The best of all is to regulate the tube by varying the intensity of the current passing through the bulb. A tube too hard for the object we desire to examine can be brought back to the proper degree by allowing a fairly strong current to pass for several minutes. If the current used is not sufficient for this purpose, pass a very heavy current for a moment. A time comes with all tubes when we must use the mechanical regulator, the same remark appl3ring to valve tubes. The form of regulator varies with the make of the tube, and all require some understanding before we can properly use them. In all cases it is better to begin reducing the tube with a minimum quantity of current and a fairly large interval of space between the cathode terminal and the regulating rod. The distance can easily be diminished, the important point being not to overdo the reduction. When radiographing some parts of the body we estimate the degree of hardness of the tube by one of the methods enumerated, i.e. alternative spark-gap, Wehnelt radiometer, Benoist scale, and then place the regulating rod of the tube at the half distance of the spark-gap required, and allow current to pass through the tube. Sparking at once goes on between the two points, and some gas is liberated in the glass cylinder at the end of the regulator. The gas passes into the interior of the bulb, the shadow on the 42 EADIOGEAPHY screen is altered, and the sparking ceases. Make sure that the regulat- ing rod is taken well away from the cathode before actually making the exposure, as a good tube may be hopelessly ruined if this simple pre- caution is not taken. The various devices for regulation of the vacuum of a tube are illustrated on the tubes. The best of all, and one which gives the operator a perfect control over the tube when working, is the air valve of Bauer. This valve can be attached to any tube or valve, and is undoubtedly a great help to the operator. Dr. Loose of Bremen, who has used this regulator extensively, speaks very favourably of it, and indeed has abandoned all other forms in its favour. In using it, care should be taken not to introduce air too rapidly, and to introduce just sufficient to maintain the balance of the vacuum. One can readily judge of the action if the tube is observed care- fully while reduction is going on. The tube may, however, get too hard for regulation. It is then a good plan to transfer that tube to another apparatus of greater strength. A tube which has hardened on a mercury break may act perfectly if placed on an installation with an electrolytic break. The primary current is much greater in the latter case, the secondary is greater, and there is more heat generated in the tube, with the result that the vacuum tends to fall and the tube to soften. A hopelessly hard tube should be put away for several weeks in a warm corner of the X-ray room or placed in an oven for several hours. This may help to reduce it sufficiently to allow it to be used, and then by regulating the current carefully it may be possible to use it for some time. When a tube has been used for a long time and gets too hard for work it is better to sacrffice it altogether. Re-exhaustion and remaking of the tube costs in many instances nearly as much as a new one, and these re- exhausted tubes are never so reUable as a new one. Consequently it is better to break up the tube, and have the valuable parts used for the construction of a new tube than to have it re-exhausted. There are many other points in the management of the X-ray tube which must be learned as the result of experience. The fact must always be borne in mind that it is the tube which is the determining factor in radio- graphy, and too great care cannot be taken of the X-ray tubes when in or out of use. Powerful currents if instantaneous do not harm the tube, but if prolonged the vacuum is lowered and the tube ruined. The quicker the exposure the more useful is the resulting radiograph Hkely to be. It should be noted that when a tube is used for all purposes, i.e. screening and radio- graphy with heavy discharges, the balance of the tube is often seriously disturbed, regulation being then a matter of increasing difficulty. It is a good plan to keep one tube for screening and another for heavy work. The efiect of the most powerful impulse on the tube is hardly perceptible, a current of 100 milhamperes or more passing through a tube for the tu-q oi a second leaving hardly any trace on the anti-cathode. This current may THE MANIPULATION OF THE X-RAY TUBE 43 be employed on the cheapest form of tube wdthout injuring it. There is, however, a tendency for a part or the whole of the current to arc round the tube if the vacuum is too high, consequently tubes with long stems or necks are necessary if hard ones are to be used. With these powerful impulses the soft tubes give the best results. While for the taking of instantaneous pictures the most powerful installa- tions are the best, it must be pointed out that quite good rapid radiographs can be produced by the use of installations of moderate power, provided the operator knows the apparatus he is using, and particularly if he possesses that knowledge of the X-ray tube which is, after all, the chief essential. The Manipulation of the X-ray Tube. — The X-ray tube should whenever possible be placed at a distance of at least 6 or 7 feet from the source of energy (coil, etc.). If used within this distance there is a probability that the magnetic field may af!ect the cathodal stream, and thus alter the focus of the tube. When the tube is supported by any form of clamp, the latter should grip the cathodal neck, below the level of the concave cathode, this being the strongest part, and should not clamp it too tightly. Before turn- ing on the current, the tube should be carefully dusted, or dried if there is any moisture present. The positive pole of the coil or other apparatus should be connected by well-insulated cables to the anti- cathode of the tube, and the nega- tive pole to the cathode. It should be seen that all loose wires or metal fittings are quite clear of the tube. The regulating wire should be placed well back from the cathode — say, at a distance of 6 or 7 inches. The point is emphasised in another portion of this work. There are exceptions to this rule in the manipulation of those tubes which work best with the regulator at a fixed distance from the cathode, according to the hardness of the particular tube and the purpose for which it is being used. The current may now be switched on, starting with all resistance in, and gradually cutting this out until the tube fluoresces brightly and steadily. If the tube is inclined to spark over, bring the regulator to within a distance of 4 or 5 inches of the cathode, so as to provide a kind of safety- valve action. This will allow of the sparks passing between the regulator rod and the cathode, and tend to reduce the vacuum of the tube and so avoid the tube becoming punctured. Before deciding that a tube needs regulation, allow it to run for a minute or two to give it an opportunity of finding its balance. Often it will be found Pig. 39. — Connection of the X-ray tubes to coil. Valve tube on positive pole. 44 RADIOGRAPHY tliat a tube so treated will settle down after a sliort run. In other words, do not be in too great a burry to regulate tbe tube. A little more or a little less current passing for a short time may successfully regulate the vacuum and allow of good work beiag done. If regulation is necessary, proceed to adjust the regulating rod at a distance which will allow sparks to pass between the rod and the cathode until the tube works smoothly, and then remove the regulating rod away from the cathode and test the tube again. Hardening the tube can only be satisfactorily done by gradually working a soft tube up through using it for very light work or for light treatment untU it attains the necessary degree of hardness. Hardening by means of reversing the current is a method which should never be resorted to. When a tube becomes hopelessly soft, the only satisfactory thing to do is to have it re-exhausted. When work is finished, if the tube is not kept permanently in position, it should be removed from its shield with great care, particularly while warm. If possible, it should then be placed upon a rack (which should be padded). Description of Methods used for Regrenepation of the Vacuum of the X-Ray Tuhe. — All tubes (excepting those of very simple construc- tion), are fitted with a device for lowering at will the vacuum or internal resistance of the tube. The proA^sion of this regulator materially increases the life of the tube. It should, however, be always borne in mind that regulation is to be regarded as the ultimate process, and not as an incidental to the working of the tube. The number and variety of the regulators of X-ray tubes is a striking demonstration of the fact that the perfect regulator has yet to be introduced. Most of the present-day regulators are efficient up to a certain point. A few of the most commonly used will be described. The Mica Regulator. — This consists of a small auxiliary chamber, in which is placed an electrode supporting a series of discs of mica. Facing the discs is a small metal knob which has no utility other than that of pre- venting a possible puncture of the tube, while regulation is taking place. Attached by a hinged cap to the mica electrode is a wire which ma}'' be brought into contact with the cathode terminal of the tube. The method of lowering the vacuum of the tube is as follows : The jointed arm, E F, is moved (by means of a piece of wood, glass, or other non-conducting substance) towards B for a few seconds, whilst current is passing through the tube, when sparks should pass between F and B. The passage of the current between the latter two points (as shown by the sparking) results in the partial suspension of the current from its normal path ; and during the flow of the current through the electrode in the auxiliary tube, a small quantity of gas is liberated, with the con- sequence that a reduction in the vacuum takes place. When this has been achieved the sparking will automatically cease, the resistance of the tube itself having become less than that of the gap F B. The wire F should THE regenp:ration of the vacuum 45 now be thrown well back, and the tube run cautiously for the first few minutes after regulation. The regulation of the tube during use may be made automatic, if desired, by placing the wire F at such a distance from B that sparking (with conse- quent regulation) takes place whenever a certain degree of vacuum is attained. This distance may easily be determined by experiment with the individual tube in use. In the case of a tube which fails to regulate by the above method, it is permissible to remove the lead from the cathode and attach it to the loop E. The current should now be passed with extreme caution, the pressure being very carefully increased until the gas is expelled from the mica. In order to appreciate the degree to which regulation is taking place, the mica disc should be carefully watched while the shunt circuit is established. It will be seen that the mica shows little flecks of red here and there, and when these appear, it is a sign that gas is being expelled. The time during which Fig. 40. — Mica regulator. (C. Andrews.) A, Anti-cathode. C, Mica disc. H B, Cathode. D, Carbon. F Wire, the current should be passed through the regulator depends obviously upon the degree of hardness of the tube, and the amount of softening which it is desired to attain ; but in any case it is wiser to switch of! the current as soon as the fiery appearance is seen in the mica, swing back the regulator wire, and test the tube ; and then to repeat the process of regulation if necessary. The regulator shown is merely a variation of the standard mica pattern, and is fitted to some smaller tubes on account of its greater convenience where a 125-mm. bulb is employed. The mechanism is the same, but in place of the hinged wire, a shaped wire is fitted on a spring and pin bearing. Normally this wire rests in the position illustrated. To effect the softening, the wire is tilted with a piece of glass or wood until F B are in contact, when the eiiusion of gas from the mica takes place. Larger models are fitted usually with a double regulator, namely carbon and mica. This consists of a chamber exactly similar to that described above, excepting that, in place of the small metal knob, there is fitted an electrode carrying a cylinder of carbon. This is capable of giving off gas in exactly 46 KADIOGKAPHY the same way as does the mica disc ; and so, in this double regulator, one has two supplies of gas upon which to draw. By means of a thumbscrew the regulator wire can be changed from one side of the regulator to the other, so that when one source of gas is exhausted, the second may be brought into use. The carbon regulator is operated in the same way as the mica, but it should be noted that there is no " fiery " appearance with the former, and also that the carbon works rather more freely than the mica. Care should therefore be exercised in order to avoid over-regulation. In the ordinary way, a current of 1 or 1^ milliamperes will cause the standard regulator to work in a few seconds, but in some cases, and especially when the regulator has been much used, a greater current may be necessary in order to heat the carbon or mica sufficiently. Experience will demonstrate this. The gases which are supplied by it to the tube allow the latter to remain constant and steady. The regenerating arrangement with which some tubes are provided, is constructed on the principle of osmosis. The metals of the platinum group, especially palladium, have the peculiarity that they allow hydrogen to pass while incandescent. A tube of palladium, closed at one end and open at the other, is sealed into the neck of the tube. To protect it against accidental damage it is covered with a test tube, which can be taken ofE. When the tube has become too hard, remove the test tube and apply a spirit flame for a few seconds to the palladium tube till it is dark red. The hydrogen contained in the spirit flame penetrates into the inside of the tube, and makes the tube softer. The flame must not be brought near the point where the metal is sealed with the glass. After the tube has been regenerated time should be allowed for com- plete coohng before it is used again. It is advisable to bring the tube to the desired degree of softness each time before it is used, and only to heat the extreme end of the palladium tube. The Bauer Air-Valve Regulator. — Another form of regulator is the Fig. 41. — Bauer air-valve. (Favre.l air-valve invented by Mr. Heiaz Bauer. This consists of a delicately- constructed valve, closed by a column of mercury, and fitted with an air METHOD OF USING GUNDELACH REGULATOR 47 filter. By means of a small Kand pump and an india-rubber tube, the column of mercury is depressed so as to open a very small aperture, through which a minute quantity of air is thus allowed to pass. The mercury rises almost immediately, and the opening is again sealed, the vacuum of the tube having meanwhile been lowered by the admission of the air. If desired, the Bauer valve may be worked with a long rubber tube, thus allowing of regulation taking place from a distance, and while the tube is actually running. Gundelach Regulator. — Another very good regeneration apparatus may be described. This arrangement consists of a little condenser which is made in the form of a cylindrical glass tube covered with an imperfect conductor of electricity. By special treatment this conductor is made to absorb a large quantity of gas. It is then covered with a second glass tube, and both cylindrical glass tubes are so treated that they cannot be pierced by a spark. '^ I > - » Fig. 42. — Gundelach tube with, regenerator. (Siemens.) a, wire. b, wire. c, metal cap. d, metal cap. When the tube has become too hard, put the wire 6 of the regenerat- ing arrangement in contact with the metal cap d of the tube. The other wire a has to be so far from the metal cap c that a shunt-spark passes. This shunt-spark should be half as long as the equivalent spark of the Rontgen tube after regeneration, because the resistance of this regenerating arrangement is considerable. The current produces some gas from the substance of the regenerating arrangement, and after a few minutes the tube will again fluoresce regularly. The regeneration, however, is only completed when the shunt-sparks have ceased to pass. After regeneration turn back both wires. This new regulator will work easily even when the resistance of the tube has become so great that no electric current will pass through the Rontgen tube. This arrangement has the great advantage that owing to the two con- ductors being separated by a glass tube, the gas is set free uniformly from 48 RADIOGKAPHY all parts of the conductors, and the whole of the gas contained therein, which is considerable, can be utilised. In order to obtain good pictures it is generally necessary to regulate the hardness of a tube each time previous to using it, and the tube should be adjusted for a medium hardness ; and this should be done by means of the regenerator. Suppression of Reverse (Inverse) Current The reverse current is obviously a great inconvenience and must be got rid of if good negatives are to be obtained. It is possible to keep it down to a minimum by using a low voltage, a high self-induction, and a low frequency in the primary coil, but if intense discharges are required we cannot suppress it entirely in this way, and other means must be adopted. Valve tubes or spark-gaps are frequently connected in series with the X-ray tubes. In a Spark-gap the current can discharge easily between a point and a plate if the point is the positive pole, but it does not do so if the point is the negative pole. It is possible, then, to create an impediment or resistance Fig. 43. — Spark-gap. (Siemens.) to the cm-rent in one direction only, whereas the passage is left free in the other. There are many types of Valve tubes, the most commonly used being the single valve tube, but the triple valve tube is also used. The nature of reverse current has already been explained. In all coil outfits this has to be checked. It is possible by a careful adjustment of primary current, interrupter, and tube, to cut this down to a minimum, but the slightest disturbance of these factors gives rise at once to a percentage of inverse current, which, if allowed to remain, has a deleterious efiect upon the tube and tends to harden it. Should it become very hard the persistence of inverse current with strong currents in the primary leads to damage of the tube ; sparking takes place, and the tube is punctured. It is generally appreciated that the current which is utilised in the pro- duction of X-rays is that which is passing when the current is breaking, e.g. when the magnetic field is at the point of collapse, and it is the endeavour to obtain a maximum tension at the moment, and to relieve or " break " such tension with sufiicient speed and completeness, that gives rise to the constant alterations and improvements — ^real or fancied — in modern medical electrical apparatus. The more complete the saturation of the induction ACTION OF REVERSE CURRENT ON X-RAY TUBE 49 coil, and the more suddenly the saturation can be " vented," as it were, through the secondary circuit, the more efl&cient (other factors being equal) the phenomenon of the Rontgen rays produced. On the other hand, the current which is passing when the current is " making," e.g. when the cycle of the magnetic field is first commencing in the primary of the coil, is flowing in a reverse sense to that of the current at " break " : and it can therefore be seen that if this current Ls allowed to flow through the X-ray tube, it cancels, as it were, a portion of the " break- ing " pressure equal to its own. Now, the result of this is not only a loss of efiiciency in that it is a loss of working current. The effects are, unfortunately, more far reaching than that, the X-ray tube becoming irretrievably damaged. In the first place, the actual passage of current in the " reverse " direction through the tube means that the anti-cathode, or positive pole of the tube, becomes, for an instant, cathode, and vice versa. Now, it is an estabhshed fact that the cathode electrode breaks up much more freely and quickly than the anti-cathode, and for this reason the cathode is always made from aluminium, which is less destructible in this sense than any other metal. But if the cuirent is reversed, and the '"' cathode " is, for the moment, the copper "anti-cathode," the destruction is much more rapid, and particles of metal are torn ofi from the surface. The fragments of copper, tungsten, etc., thus detached are projected with enormous rapidity towards the wall of the tube, to which they adhere, forming a thin metallic coating, particularly on the back zone of the bulb {e.g. behind and above the plane of the surface of the target). The result of this coating of metal is to absorb all the free gas in the tube, and is the explanation of an old blackened tube remaining often dead hard, however much it may be regulated or re-exhausted. The blackening described above must not be confused with the violet coloration in front of the plane of the target, which latter is a normal condition in all tubes after use, and which is free from objection. The second ill-effect is that of overheating. If the usual form of milli- amperemeter, known as the " moving coil " type, be employed, its reading is that of the difference between the " correct " and " reverse " currents. For example, supposing the current in the right direction to be equal to 2 milliamperes, and that in the wrong or reverse direction to be equal to 1 milliampere, the milHamperemeter would indicate 1 milliampere. But although this would be accurate so far as the measuring of the current itseK went, it must be remembered that the heating efiect of an electrical current increases as the square of the amperage. So that, although the operator may say, " The tube is all right ; it is taking only 1 milliampere," we are subject- ing it to the strain of 3 milliamperes so far as heat is concerned, e.g. nine times the heat of a real 1 milliampere current. As has already been pointed out, it is mainly the heat which destroys the balance of the vacuum of the X-ray tube. It is admittedly a very difiicult matter to construct a modern installation which shall be free from reverse current, particularly as with the higher 4 50 RADIOGRAPHY amperage which is demanded for rapid work, high voltages must also be employed, and the greater the voltage the greater the reverse discharge. The only means, therefore, of combating the evil is to introduce some device which shall " rectify " the discharge, e.g. eliminate the reverse current while interfering with the proper current as little as possible. In order to effect this, many contrivances have been tried, notably a simple " spark-gap " and various forms of mechanical rectifiers. The most usual and most efBicient method is, however, the valve tube, a vacuum tube which permits the current to pass unobstructed in the right direction but which should suppress absolutely the reverse or making current. Single Valve Tube. — This valve tube, owing to its special construction, is much less inclined to become hard than the simpler types of valve tubes. It is, however, fitted with the new regenerator so that it can be maintained at a uniform degree of softness ; this should be maintained at about 16 mm. equivalent spark-gap. When the tube requires regenerating one wire should be connected to the anode cap (positive), and the other held at a distance of about 5 mm. from the cathode cap (negative). As soon as the tube shows a white foggy light the regeneration is finished. m. )^-*^ Fig. 44. — Single valve tube. (C. Andrews. Fig. 45. — Trii:)le valve tube. (C. Andrews.) Formerly when it was desired to rectify on higher voltages, or while using heavy currents, two or more valves were placed in series; but a difficulty then arose by reason of the fact that such valves did not always increase in hardness to the same degree, and it was therefore almost impossible to maintain an efficient rectification, and, at the same time, to pass the full amount of current needed. In order to overcome this trouble a " double " valve was designed, consisting of two bulbs and sets of electrodes, each exactly similar to one single valve, but joined together in such a manner that one vacuum is common to both chambers. The latter are then con- nected in parallel, and placed in series with the X-ray tube, the result being that the backward resistance is doubled, the current flowing between the two sets of electrodes. With such a double valve, complete rectification on voltages up to, say, 200 is obtainable. The Triple Valve is constructed similarly to the foregoing, but has three VALVE TUBE8 51 intercommunicating chambers, and is intended for use on the highest voltages and for the heaviest discharges. Valve tubes may be had either of clear glass, of blue, or of a deep amber colour. The latter is preferred by many workers, as the colouring serves to disguise the fluorescence, and thus permits of a better judgment of the condition of the Eontgen tube itself. High-tension Rectifier. — A different form of valve is that known as the high-tension rectifier. It consists of a long aluminium f mmel and a curved mirror, the bulb being spherical, and of a diameter of approximately 18 cm. This form of valve is very efficient, even on high voltages, but it has a ten- dency to increase in vacuum somewhat rapidly. For this latter reason an osmosis regulator is provided, so that regulation is possible as often as desired. French Type. — Yet another form is that known as the " French type," which is very similar to the single valve. It has, however, in place of the plate anode, a thin pin with a slightly flattened head, and the neck of the Fig. 46. — French valve. (C. Andrews. Fig. 47. — Oliver Lodge valve tube. (Cossar. tube surrounding this is of much smaller diameter than in the other cases. The action of this valve is very perfect, complete rectification being obtained without any appreciable loss of current. The French pattern is, however, rather more delicate than the others, and also tends to go up in vacuum rather quickly. The provision of an osmosis regulator permits, however, of the latter trouble being overcome. The Oliver Lodge valve tube is often used. It has the disadvantage that it cannot be regulated, but it is claimed for it that it does not require regula- tion. This claim is open to question. When it is necessary to check the reverse current which is found when very heavy discharges pass through a tube a number of these valve tubes may be placed in the circuit. Regulation of the Valve Tubes. — The regulation of valve tubes is efiected in a similar way to that of X-ray tubes, according to the type of regu- lator in use. In the case of the mica or carbon patterns, the lead which is normally attached to the plate (anode), should be attached to the ring of the regulator, and current passed until the blue appearance has been restored to the valve tube. The lead must then be reconnected to the anode terminal. 52 RADIOGRAPHY Valve tubes should never be worked "hard." An intermediate vacuum, giving a Geissler discharge in the body of the tube, with a slight apple-green tint round the spiral base, will be found best. Do not forget also, that a '■' hard " valve tube may be emitting an appreciable quantity of Rontgen rays, with a consequent need of protection for the operator. ,0=€t \ Fig. 48. — Gundelach valve tube. (Siemens.) Bauer Air-valve. — The latest improvement in the valve tube is the intro- duction of a Bauer air-valve for the regulation of the vacuum. This is very useful and easily handled by the use of a small hand-pump, a long rubber tube allowing of regulation from a distance. When intensive currents are used it may be necessary to put a valve tube on each pole or even to have 6 or 8 valve tubes in series. By using valve tubes the amount of inverse current can be practically abolished when medium currents are employed, but when very heavy currents are used it is not possible, or hardly ever possible, to abohsh it. There are several other varieties of valve tube of more recent construc- tion. The various types described are useful on installations of medium power, but if they are used on the more powerful installations of recent date, they soon begin to vary in hardness, and add considerably to the diflS.culties of the radiographer. This is particularly noticeable when the installation is used alternately for short exposures and long ones. The balance of the valve tube is disturbed, and it will require almost constant regulation. It should be pointed out that when valve tubes are used they require nearly as much regulation as the X-ray tube. When the X-ray tube is known to be right and the results are not satisfactory, attention should be paid to the condition of the valve tube. Of the more recent type of valve tubes the most efficient is one manufactured by the Polyphos Company. Valve tubes from America are promised which should be a great improvement on the ones at present in use in this country. DETECTION OF INVERSE CURRENT 53 Method of Detecting- lleverse (Inverse) Current.— A good guide to the presence of reverse current is the appearance of the tube in action, rings then appearing on the aspect of the tube behind the anti-cathode, and the green light in front not being so clearly cut as when there is no trace of reverse current. See frontispiece. The continued presence of reverse current leads to changes in the con- dition of the tube. It gradually hardens, and the change in its state may show itself in a variation in the sounds produced when in action. The best method of detecting reverse current is by the use of an oscillo- scope tube. The construction of such a tube is worthy of description. Two aluminium wires, separated by a small gap, are enclosed in an oblong glass Fig. 49. — Oscilloscope tul.e. (Siemens.) tube, and the wire connected with the negative pole becomes, when the current passes, surrounded by a violet fluorescence. If the current discharges in one direction, only one of these wires shows the violet light, but if each wire is alternately negative and positive both wires become fluorescent and the length of the fluorescent band indicates the intensity of the current, so that we can compare the relative strength of the closing and breaking currents. There are several varieties of tube but the diagram illustrates the general type in use. The instrument is useful. It records the current passing in one direction through the tube. If reverse current is present it represents the difference between the two currents. When both are equal then no reading is recorded. If the reverse is greater than the current in the right direction, then it records on the wrong side of the zero mark. When the oscilloscope tube shows that reverse current is present, then valve tubes must be used to check the reverse. The combination of milliam- peremeter, valve, and oscilloscope tubes is a most useful one, helping greatly to regulate the exposures. The X-ray tube afiords an excellent indication of the presence of reverse current. The change in the appearance of the tube which has reverse current passing through it is illustrated in the coloured frontispiece. Fig. 50. — Oscilloscope tube in action. (Schall.) a, The appearance of a tube with the current passing in the right direction with a trace of reverse current. h. The appearance with the current passing in both directions in almost equal pro- portions. 54 EADIOGKAPHY Secondary Radiations, Cause, and Methods of Suppression. — Secondary rays are produced by the reverse current. All those X-rays which do not emanate from the focus of the anti-cathode are called secondary rays. They have the same penetrating power as the primary rays and are plentiful in hard tubes, but they project the outlines of the objects in other directions than the primary rays, and a loss of sharpness results. When they are present it is necessary to do something to prevent deterioration of the negative. Secondary rays are also produced, or a diffusion of the primaryrays takes place in the patient's body. It is probable LCBA ABCD Fig. 51. — Diagrams showing the paths taken by primary beams and secondary rays. (Schall.) that both of these manifest themselves during a long exposure. Fig. 51 shows the path taken by the primary beam, and the manner of projection of secondary rays upon the photographic plate. The X-rays, A A, emanating from the focus of the anti-cathode project a shadow, B B, of the object, 0, on the plate. If there were no secondary rays this shadow would be of uniform darkness from B to B, and the space, BCD, would be free from any shadow. But if any current discharges in the wrong direction, the so-called secondary rays are generated on the glass of the tube. They are indicated by the dotted hues h b. Although weaker in intensity, they project shadows, and in another direction than the primary rays will do ; the shadows overlap, and the part between A B will not be so SUPPRESSION OF SECONDARY RADIATIONS 00 dark as that between A A and the space between B C mil not be as clear as that between C D. The effect of the secondary rays is therefore to make the outlines less sharp, and to cause a general fogginess. In consequence of this some details will become indistinct and the finer ones will disappear entirely. In order to minimise the effect of the secondary rays produced by reverse currents upon the plate, diaphragms are used. A diaphragm alone is not sufficient, and an extension tube should also be combined with the diaphragm. The following illustration shows this method of checking these ill-effects to some extent. The illustration (Fig. 52) shows the primary or principal rays a a emanating from the anti-cathode A ; the dotted Hues 6 h indicate secondary ^ =6 Fig. 52. — Diagram showing the use of a dia- phragm between tube and plate. (Schall. ) Fig. 53. -Diagram showing the use of a cylinder diaphragm. (Schall.) rays emanating from the glass wall of the tube. If we place a diaphragm between tube and plate, some of these secondary rays are stopped, and, the nearer the diaphragm to the tube, and the narrower its aperture, the more efficient will it be. But as metal plates cannot be brought quite close to the tube, some secondary rays will still reach the plate unless a cylinder diaphragm is employed. Fig. 53 shows why a cylinder diaphragm is bound to exclude more secondary rays than a flat diaphragm can do; the cylinder diaphragm can also be used with advantage for compression. Instruments for Estimating the Hardness of the X-Ray Tube. The X-ray bulb in action presents a picture which in itself is a guide to the condition of the tubes as regards hardness, presence of inverse current, and radiographic value, but if good work is to be maintained it is necessary 56 KADIOGEAPHY Fig. 54. — Adjustable spintermeter. (Watson.) to be able to record the actual conditions under which a particular standard has been attained. When this has been done it should be possible to repro- duce the condition of tube necessary at any time. There are several methods for estimating the degree of vacuum (or hardness) of the X-ray tube. These are (a) measurement of the alternate spark-gap, (6) the Bauer QuaUmeter, (c) radiometers : (1) Walter, (2) Walter- Benoist, (3) Wehnelt crypto- radiometer, (4) measurement by the milhamperemeter. A rough though practical method of estimating the inter- nal resistance of the X-ray bulb consists of the Spintermeter, by means of which the alternate spark-gap is measured. A convenient form of spin- termeter is here shown. The action is simple. The point A is withdrawn to its limit, and the tube set in action. By gradually approximating the point A to the point B a position is reached when the current, instead of passing through the tube sparks between the points A and B, a scale attached giving the distance in inches or centimetres. The spark-gap is measured, and gives approximately the hardness of the X-ray bulb. The spintermeter may be attached to the coil, or more conveniently mounted on a separate base, and placed at some distance from the coil. The Bauer Qualimeter is an instrument for determining the degree of hardness of the X-ray tube. It is useful, but not always to be relied upon. This instrument is connected by a wire to the negative terminal of the coil or the cathode of the tube. It is a static electrometer and condenser which indicates automatically the potential of the cathode, and hence the quality of the X-rays. The apparatus consists of two wings, which swing between two fixed plates. Both wings and plates are equally charged, so that a repulsion takes place between them. Fig. 55.— Bauer qualimeter. (Favre. The intensity of this repulsion is in exact proportion to the electrical tension in the secondary circuit, and is indicated by the deviation of a pointer over a suitably divided scale. As is well known, the penetration of the X-rays is a function of the BAUER QUALIMETER 57 electrical potential in the secondary circuit, so that a simple measurement of this potential between the anode and cathode will give as an indication of the hardness of the tube. The scale is gauged according to the absorption of the X-rays by sheets of lead of different thickness, increasing regular from one-tenth of a millimetre to one millimetre. No. 1 on the scale denotes X-rays of such a hardness as to be totally absorbed by J^^J millimetre of lead. When the index is at No. 10 we know that the tube is giving out rays which will penetrate 0-9 millimetre of lead, but will be totally absorbed by 1 milhmetre of lead. As already explained, the instrument is unipolar, being joined up by a single wire to some point in electrical connection with the cathode. The instrument is contained in an ebonite case, which swings freely from a bracket on the wall or a stand, so as to be always in a vertical position. The following experiment will demonstrate the use of the instrument. The tube is disconnected, and a current from the generator is sent through the spark-gap. In this case the deflection of the qualimeter becomes greater with the increasing spark-gap, while the reading of the milliamperemeter recedes. The spark-gap itself is often used for gauging the hardness of the tube. This proceeding, however, is not exact enough for practical purposes, as the resistance of the spark-gap is dependent upon the form of the electrode ball, point, or disc, and upon the humidity of the atmosphere. No metallic surface should be allowed to be within a distance of 8 to 10 inches from the instrument. The purposes for which the qualimeter can be used are the following : Therapeutics. — ^It is becoming more and more imperative to regulate the hardness of the tubes to the various diseases treated. As modern pubhcations almost always give the degree of hardness in qualimeter degrees, it is obviously necessary to employ the qualimeter to obtain the same results. The spark-gap, which has very generally been used up till now, is to be rejected for the reasons mentioned above. In addition to this it is possible by the help of the qualimeter, to use the so-called indirect calculation of the erythema dose instead of the direct measurement by the Sabouraud pastille, in cases where the degree of hardness employed is always approximately invariable, as is the case in the treatment of the skin and deeper tissues. The process can be shortly described as follows : Take a new X-ray bulb and give an erythema dose, noting the reading of the milliamperemeter and the qualimeter and the time. The product of these three factors — time, milliamperemeter, and qualimeter degrees — will be always found the same for the erythema dose (under an approximately unvarying degree of hard- ness), however much the two other factors — intensity and time — may be varied. This method has been scientifically proved by Klingelfuss of Basel. A practical example will serve to illustrate the above. If an erythema dose has been reached in ten minutes with a hardness of 3 Bauer-degrees and an intensity of 4 milliamperes, the product will be 10 x 3 x 4=120, If a bulb is being employed which registers 3 degrees of hardness with an intensity of 58 EADIOGRAPHY 2 milliamperes, it will take twenty minutes to produce the same result : the product will again be 2 x 3 x 20=120. For treatment of the skin and deeper tissues, two different degrees of hardness are generally used (for example, 3 Bauer and 7 Bauer), and the erythema dose need only be calcula- tive once for all. Shght fluctuations in hardness make no difference, and if they occur during exposure they can be adjusted by regulating the primary current. On the other hand, the current employed must be kept within such bounds that the tube remains steady. Should the current through the tube be too strong or too weak, more or less current may be passed through the tube by adjusting the shunt. Too weak a current hardens the tube, whereas too strong a current has the opposite effect. For comparative scale of the usual instruments for measuring the hardness of tubes, see page 61. Technique for Exposures. — The time of exposure can be calculated in the same way as that for an erythema dose. We first ascertain within what time and with what degree of hardness and intensity a good Rontgen negative of any particular region is obtained. These readings may be noted on a chart hung within the protective cabin, and in this way, by using the same figures, a satisfactory result can always be obtained, and failures excluded. It is here that the qualimeter is particularly useful, since different degrees of hardness are required for the production of good pictures of various parts of the body. If the operator prefers to use one tube for all purposes, he will find the Bauer air-valve tube most practical. With this he is able to adjust the tube to any degree of hardness desired. For in- stantaneous exposures the most important point is to adjust the hardness of the tube so that a sufficient number of hard rays may be emitted. To ascertain this, the tube should be driven with a normal intensity of 2 milli- amperes, and the hardness tested by the qualimeter. From the resulting negative it can be immediately ascertained whether the tube is too high or too low. If the picture is too faintly shaded, the degree of hardness was too low ; if it is too dark, the degree was too high. As the result of considerable experience in the use of this instrument it may be stated that the quahmeter is particularly suited for radioscopic work, since it indicates the hardness of the tube at a distance, and without the operator being brought into dangerous proximity to the tube in order to measure its hardness. As has been said, the qualimeter has not only created a possibility of working with greater exactness, but — and to this we again call particular attention — ^it is not now necessary to come within the dangerous area for the purpose of ascertaining the degree of hardness. Finally, with its help the tubes can be worked much more economically. Radiometers. — These serve to determine accurately the degree of hardness of the tubes, that is to say, the penetrability of the rays. Walfer^s Radiometer consists of a sheet of lead mounted on a wooden frame and with eight circular holes, combined with an adjustable fluorescent screen. The holes are covered with platinum foil of a thickness varying in RADIOMETERS 59 geometrical progression from '•t)05 mm. for hole No. 1 to '64 mm. for hole No. 8. If the apparatus is placed in the path of the rays a certain number of holes become visible on the fluorescent screen, the number depending on the hardness of the tube. The degree of hardness is indicated by the largest cypher marked on the visible holes. Fig. 56. — Walter's radiometer. (Siemens.) The Walter-Benoist Radiometer has aluminium apertures of various thicknesses and a piece of silver foil. One of the aluminium apertures will show the same degree of brightness as the silver foil. The cypher on this aperture indicates the hardness of the tube. Fig. 57. — Beuoist radiometer. (Siemens. ) Fig. 58. — Protected front for Fig. 57. A simple form of Benoist radiometer, with slots for screws, may be fixed on the fluorescent screen ; the lead glass covering the latter protects the operator. Wehnelt's Crypto-Radiometer is an improvement on the foregoing radio- meters. It is provided with a wedge-shaped aluminium strip, and alongside this a flat silver strip, both of which can be moved by means of a ratchet over a brass plate provided with a thin slit. The apparatus is adjusted until both strips show the same degree of brightness on a fluorescent screen. A scale indicates the position of the aluminium strip, i.e. the penetration of the tube. This is a useful instrument ; it is efficiently protected, and will be 60 RADIOGRAPHY Fig. 59. — Wehnelt's crypto-radiometer. (Siemens.) found to be extremely useful for routine work. The radiometer can be fitted betdnd the lead-lined screen, and a suitable tube-holder attached to the tube while it is being tested. A sht must be cut in the lead linings of the screen. Then the apparatus may be used with safety. When using these radiometers, and particularly at the present time when heavy currents and hard tubes are coming into general use, it is necessary to point out that the protective devices supphed with the measuring apparatus are not nearly sufficient for the protec- tion of the operator if many observations have to be made daily. The instru- ments should be mounted on a screen lined with thick lead, and the slots for comparing standards should have thick lead glass. The instruments described all esti- mate more or less accurately the hard- ness of the X-ray bulb. There are also instruments which measure the quan- tity of current actually passing to the tube. These are useful in estimating the exposure necessary at particular times. Later, the exact method of combining all the factors required for the estimation of exposure will be described. For our present general purpose it is sufficient to state that there are instruments used to measure the current passing through the tube, the actual quantity of which will vary with the internal resistance of the tube. For example, a soft tube will allow, say, 10 milliamperes to pass, whilst with the same primary current a much harder tube will only allow, say, 1 milli- ampere to pass. Measurement of X-Rays by Milliampepe- meter. — A milliamperemeter is necessary for this' purpose when radiographic exposures are given, and acts by estimating the quantity of current passing through the X-ray tube. That shown is a Deprez-d'Arsonval moving coil in- strument, and it is an advantage to have the zero in the centre of the scale for measuring positive and negative currents. They do not show the actual current traversing the X-ray tubes, but its mean value, which can, however, be taken as a relative measure of the intensity of the rays. So long as the pointer remains stationary this indicates that the hardness of the tube is con- stant. Should the tube, when in use, become harder, the pointer will move towards zero. The instrument is as a rule specially constructed so that it is impossible for sparking to occur inside, and the pointer should be well damped. There are other instruments for Fig. 60. — Milliamperemeter. (Siemens.) MEASUREMENT OF HARDNESS OF TUBES CI measuring the quantity of X-rays used in dosage. These are described more fully in the section on Radio-therapeutics. The table below gives the comparative values of the instruments most frequently used, namely : Bauer, Wehnelt, Walter, and Benoist. Comparative Scale of the usual Instruments for measuring the Hardness op Tubes soft medium hard Bauer .... 1 2 3 4 5 7-5 6 7 8 9 10 Wehnelt 1-5 3 4-5 6 9 10-5 12 13-5 15 Walter 1 1-2 2-3 3-4 4-5 5-6 1 6-7 7-8 Benoist 1 2 3 i 4 5 6 7 8 9 10 The ingenious method used for the control of the Coohdge tube appears to be the perfect one for the estimation and control of the hardness of the X-ray given off from the bulb. The penetrating power of the X-rays is dependent upon the speed of the cathode stream, and the latter is varied by increasing or diminishing the potential at the terminals of the tube. The provision of an ammeter in the battery circuit gives the means necessary for estimating the hardness of the ray. The miUiamperemeter in the secondary circuit gives the current passing through the secondary circuit. By using these two indicators together it is possible not only to estimate but to produce at mil a particular and fairly constant type of X-ray. This not only dispenses with other more tedious methods of estimation but enables the operator to reproduce at any time the particular ray he may require. TUBE STANDS, COUCHES, COMPRESSORS, AND SCREENING STANDS The X-Ray Tube-Stand There are many varieties and adaptations of this piece of apparatus. The chief essential is that the shield, whatever it may consist of, should be efficiently protective, and of a size capable of holding easily the largest tube. The clamps should have an easy movement, and as little metal as possible should enter into the structure of the shield and tube clamps. This is particularly desirable when heavy currents are used, for otherwise the current may spark from the tube to the metal, and lead to a marked diminution of current passing through the tube and to disappointment in results. The tube is frequently punctured if these precautions are not taken. There is a type of protected tube-stand which, with some modifications, is made by all the principal manufacturers, and its essential points are enumerated below. Such a stand will answer very well, not only for thera- peutic work, but in small installations for radiography and radioscopy. It consists of a wooden tube-box, fined with protective rubber, and as some of these boxes err on the small side, this is a point that should be noted. To the front of this box all diaphragms, applicators, and pastille-holders can be fitted. This box is attached to a horizontal wooden arm by a mechanical method, and this part should be carefully examined to avoid subsequent disappointment and annoyance. As the tube-box may have to carry con- siderable weight and still be used at all angles and positions, each move- ment should be controlled by a separate solid metal clamp, and not by one that can wear or compress. It is better to pay a little more for extra work in this direction than to court disaster by some part not holding well, and perhaps allowing the tube-box to drop in the middle of an exposure. The horizontal wooden arm has a rack-and-pinion adjustment, which is fitted by means of a bracket, with a vertical rack-and-pinion movement attached to a wooden upright, which in turn should be mounted on a solid metal base, not a wooden one, so as to make a stable and fairly rigid apparatus. All adjustments can then be conveniently made. An elaboration of this is the pillar tube-stand, suitable for use with much larger outfits and for all kinds of work. Description and Use of Pillar Stands. — The pillar stand (Fig. 61) consists of a solid pedestal with castors, which carries a vertical column of 62 THE PILLAR TUBE -STAND G3 steel tube. An adjustable sleeve, to which one end of the wire is secured, is mounted on this column. The wire runs over a pulley, and carries a movable lead weight inside the steel tube, which serves to balance the tube- box and the whole movable system. The sleeve can be locked in any position by the lever. The pulley is secured to a ball-bearing, and can revolve freely round the top of the column. The sleeve has a horizontal Fig. 61. — Pillar stand, protected tube-box and accessories. (Siemens. arm, which carries a second sleeve. In order to avoid a displacement of the sleeve in the longitudinal direction of the arm, the latter has a groove at the end, which engages the screw of the lever. The tube-box is hinged to the sleeve in such a manner that it may be revolved horizontally through an angle of about 90°. In order to fix the position of the angle, there is a circular slot above the hinge, through which travels the screw of the lever. If, now, the lever is turned to the right, its head is firmly pressed against the 64 EADIOGKAPHY slot, and thereby prevents any further rotation of the hinge. The sleeve, together with the tube-box, can be turned radially to the arm. The sleeve is locked by tightening up a screw by means of the lever, so that the sleeve is pressed on to the arm. Thus, the tube-box can be moved as follows : {a) up and down ; (6) round the column ; (c) round the arm ; {d) through an angle of 90° round any axis vertical to the arm, so that this pillar stand permits of adjusting the position of the tube within the widest limits. The tube-box itself is lined inside with lead rubber material, as a Fig. 62. — A form of tube-stand, which combines many useful mechanical move- ments, (Watson.) Fig. 63. — A convenient type of tube- stand with iris diaphragm. protection against accidental effects of the rays. Its back forms a door. The front is provided with a rectangular opening of about 170 x 220 mm., in which the accessories subsequently to be described are inserted. In order to be able conveniently to manipulate the tube-box during adjustment, it is provided with a handle. One of the sides is fitted with an observation window of lead glass, through which the X-rays can only penetrate with difficulty, and this may be closed by the shutter, when making a fluoro- scopic examination. Two pieces of wo©d with slots are fitted to the under side of the box, between which the -tube-holder, together with the tube THE TUBE STAND 65 is inserted. The holder must be secured to the cathode neck of the tube. The latter must be so mounted that the anti-cathode is turned towards the front of the box (with the opening for the X-rays), and occupies about the centre of the box. The tube-holder can be fixed by turning the wood screw to the right. In order that neither the operator nor the patient may receive shocks due to sparks jumping from the tube to any part of the stand, a terminal is mounted on the pedestal, which is connected ^^^th all the metal parts of the stand, and also with the accessories, which are inserted in the front opening of the box through the metal strip which runs along the tube-box. This terminal must be connected to a water-pipe by means Fig. 65.- FiG. 64. — Tube-box with extension tube. -Tube-box with rectangular diaphragm. of an insulated or bare wire, or to an earthed conductor, should this be avail- able on the supply mains. In order to prevent any accidental movement of the stand, two screws are provided in the pedestal by means of which the latter may be slightly raised, so as to put the two castors out of gear. Accessories. — 1. A wooden Carrier with an opening (about 170 x 170 mm.), which is inserted in the front of the tube-box, and feed by means of the screw. In order to centre the X-rays, it may be adjusted up and down to the extent of about 30 mm. The accessories mentioned subsequently, compressor diaphragm, iris diaphragm, and holders, can be attached to this carrier ; for this purpose it is provided with a small spring, which snaps into a corresponding small slot in the accessories themselves, and thus prevents them from falling out when the tube-box is rotated. The carrier should be so inserted in the box that the spring is on the same side as the screw, so that the metal strip makes metallic connection with the strip on the opposite side, and thereby the metal parts of the carrier, as well as of the accessories which it carries, are earthed, 2. The Compressor Diaphragm, of about 140 mm. long by 125 mm. diameter, which serves, like the compressor diaphragm of Professor Dr. Albers-Schonberg, to produce radiographs with good contrasts, this being 5 66 KADIOGRAPHY attained primarily by screening the rays not required, and partly by efficiently fixing or compressing the patient. 3. An Iris Diaphragm, which must be inserted in the carrier in such a manner that the spring snaps into the slot. The largest diameter of the opening is about 105 mm. and the smallest about 25 mm. 4. A Holder, which must be inserted in the wood carrier, and is intended for holding the three diaphragms as well as the centering device. This holder must also be inserted in such a manner that the spring snaps into the corresponding slot. A Holder for the lead-glass tubes, or applicators, which must also be inserted in the wood carrier. The tubes can be fixed by turning a wooden screw. 5. Four Lead Glass Tubes, of 100 mm. length, with diameters of about 18, 40, 50, and 75 mm. respectively. The largest tube is conical, and should be inserted into the carrier at its widest end. 6. A Centering Device, which consists of a small metal tube attached to a circular plate, to the free end of which a small circular screen of barium platino cyanide is attached. The centering device must be inserted in the holder. In order to centre the tube, the latter is switched on, and the wood carrier with the centering device is moved until the small fluorescent screen is in a state of complete fluorescence, that is, until it shows a complete circle and not only a part of the circle. Centering can also be well effected without the tube being switched on, by removing the cap and the little screen from the centering tube, and observing the anti- cathode through the latter, and then adjusting the tube until the centre of the anti-cathode is observed. 7. A Shutter Diaphragm, the aperture of which can be variably adjusted by means of levers, in the form of a rectangle. The largest aperture is 120 X 120 mm. 8. Holders for the Tubes. — In order to avoid the unnecessary removal of the tube-holder from the tube, when another tube is employed, extra tube-holders are recommended, so that with this arrangement the tubes are always centered when they have once been adjusted. 9. A Pastille Holder. — This can be inserted in an opening in the base of the box, and is provided with a circular slot, in which the re-agents of the Saboraud and Noire radiometers are inserted. By turning the metal piece the re-agents are prevented from falling out. Instructions for Use. — The stand is earthed, as already described, by connecting the terminal by means of a wire with gas or water pipe, or possibly with the neutral wire of the supply mains. When moving the tube-box, the handle can always be held with one hand. In order to adjust the box, it should be brought to the desired position by loosening the lever, and then fixed rigidly at once by means of the same lever. This lever when loosened should only be turned so far as to enable the box to be easily revolved. Then the box can be turned into the desired position round the arm, and &Ked again by means of a lever. Finally, the box is raised to the desired height, and if necessary rotated round the colunm, THE X-RAY COUCH 67 and then tightened up again by means of the lever provided. Care should always be taken that the fixing screw for the tube-carrier is well tightened up, so that the wood carrier does not fall out when turning the box. Should it be desired to apply fluoroscopy or radiography to thick parts of the body, the wood carrier front may be completely removed. Couches and Stands A simple couch will suffice for a small installation. In large institu- tions, where a considerable amount of work has to be got through quickly, a couchi with mechanical contrivances is necessarv. The couch should be Fig. 66. — A eouvenieut form of X-ray couch. (Siemens.) jPitted with a protected tube-box, the top of the table is so constructed that the patient may be moved in several directions to facilitate centering of parts of the body over the X-ray tube. sufficiently protected, and should have conveniences for working with the tube below the table. When possible overhead work should be undertaken. Tfiis compressor is a most important piece of apparatus, mounted upon a suitable table with adjustments and tube-carriers, and is a great help tto the radiographer, since it facilitates the work and saves time if the adjust- anents are easily worked. There are many forms to select from, and a great deal must be left to the individual worker. The Albers-Schonherg Compressor is the best-known pattern, and such a compressor apparatus has become an absolutely essential auxiliary for radiography. The chief advantages which are guaranteed to the radio- grapher by its proper use may be briefly summarised as follows : 1. By means of the compressor diaphragm the secondary rays which affect the value of the radiograph can be screened completely. 2. The parts under examination can be kept absolutely at rest, so that 68 RADIOGKAPHY Fig. 67.— Albers-Sclionberg compressor. (Siemens.) Fig. 68. — A couch fitted with protected tube-box underneath. (Butt.) This has movements in three directions, and is arranged for stereoscopic work. Au upright attached to the box carries a horizontal arm to which is fitted a plumb-line to indicate the exact position of the anti-cathode of the tube. On the upper aspect of the couch a movable tube- holder is fitted. This has attached to it a compression diaphragm. It is also arranged for the taking of stereoscoj^ic negatives. ON THE USE OF THE COMPRESSOR 69 want of sharpness, due to voluntary or involuntary movement, to respiration or pulsation of the heart, is eliminated. 3. All parts of the human body can be radiographed, so that the com- pressor apparatus can be employed for all exposures required, \\^th the exception of general exposures over a large area of the body. It is now generally recognised that a certain quantity of X-rays are given off by the glass walls as well as by the other metal electrodes of the tube, in addition to the bulk of the X-rays emanating from the anti-cathode. Owing to the presence of inverse current in the tube, some cathode rays are produced from the anode, and others also start from the edges of the cathode, and these are all converted into secondary X-rays. These secondary X-rays, which are produced in much larger quantities in hard than in soft tubes, are the primary cause of lack of definition, detail, and contrast ; they produce general fog in negatives, and so lessen the value of the results of the more difficult radiographs. The compressor apparatus consists of a lead-lined metal cylindrical or rectangular box, with an opening at the upper end for the insertion of diaphragms. The cylinder effectu- ally absorbs and screens off all stray secondary rays, allowing only those X-rays emanating from the anti- cathode to reach the photographic plate. This can be proved at any time by observing a fluorescent f^g. gg.-Extension tube of a Kidwig compressor screen placed below the cylinder, to show method of compression. (Siemens. ) when a brightly illuminated centre only will be seen ; a wider circle of fluorescence, indicating the presence of stray secondary rays, is only observed when inefficient diaphragms are employed. By the time the X-rays have traversed the distance between the tube and the fluorescent screen or photographic plate, they have become very much diffused, and the thicker the subject the greater the diflusion. The primary object, therefore, is to reduce this distance in order to obtain quicker exposure and sharper and more brilhant radiographs, and for this purpose it is' necesary to combine a compressor with the cylinder. The end of the cylinder is fitted with an ebonite rim, and the whole apparatus is raised and lowered by a lever. Some parts of the human body can be compressed three or four inches without causing any discomfort to the patient, and the time of exposure is thus very greatly reduced. The compressor is also of great use in reducing the movement due to respiration, and thereby conduces to greater sharpness and definition in the radiograph. There are modifications of this type of compressor which are preferred by some workers, and possess advantages over the Albers-Schonberg. The compressor introduced by Dr. Gilbert Scott possesses all the advantages 70 RADIOGRAPHY of the Schonberg apparatus, and is much more adaptable and easy of manipulation. The Upright Screening" Stand. — This useful piece of apparatus may be simple or very complicated, with conveniences for stereoscopic exposures. All movements must be easy. Several types of screening stands are illustrated. The most useful are Levy-Dorn, Wenckebach, the extremely Fig. 70. — Screening stand arranged for stereoscopic work in the ^ipright position. (Butt.) The apparatus is arranged so that tube- and plate-holder move automatically at the right moment. The whole mechanism is controlled from the switch table. ingenious but complicated one designed by Schmidt of Berlin, and the apparatus of Butt with automatic stereoscopic movements. Care should be taken to ensure the complete protection of the operator. The fluor- escent screen should have protected handles, and the front must be pro- tected by thick lead glass. This should be tested to make sure that it is efficient. The Levy Dorn Screening Stand is constructed in such a manner that it SCREENING STAND 71 can be used for other purpo'ses in addition to screening, and so it forms a very complete type of apparatus, particularly in small hospitals where the space devoted to the X-ray department is very limited. The ap- paratus consists essentially of a large, totally enclosed protective lined tube-box, with lead-glass observation window fitted with sliding shutter on one side ; at the back is a door and on the front is fitted the dia- phragm, compressor tube, and other pieces of apparatus. This tube-box is mounted on a carrying frame, which is fitted A\dth slots, so that it can be brought nearer or taken further from the patient, also the whole box can be entirely rotated. The frame carrying the tube-box is attached to a strong square framework, running up and down between the upright sides of Fig. 71. — Screening stand arranged for work beneath the table. (Siemens. ) Tig. 72. — Screening stand arranged for examina- tions in the upright position. (Siemens.) the stand. This frame is fitted with counterweights, so as to move freely up and down, and on the front of it are two rods projecting forward, and sliding on these rods is a metal carrier and carriage for holding the fluorescent screen or plate-holder, which can be angled to follow the contour of any part it is desired to examine or radiograph. The whole of the control of this ap- paratus can be manipulated from the front, so that it is entirely unnecessary for the operator to put his hands near the tube-box. As will be seen, the fluorescent screen can be moved freely across the patient by means of its own protective handles ; the aperture of the diaphragm is controlled by means of the two flexible cables and handles seen on the right in Fig. 71 ; the handle on the left-hand side causes the tube-box to travel from side to side at the back, and the large wheel seen on the right is for raising and lower- ing the whole of the frame carrying the tube-box and screen-carrier. Now, 72 KADIOGKAPHY Fig, 73. — Screening stand arranged to work as a compressor. (Siemens. ) as to its other purposes, the tube-box can be lowered to the ground and rotated, a quarter-revolution bringing the opening of the tube-box towards „, the ceiling of the room. A couch or table can be moved over the box in this position, and examinations and radiographs made with the tube below. Or, on the other hand, the tube-box can be rotated from its screening position a quarter-turn in the other direction, so that the aper- ture is towards the floor. The frame carrying the tube-box can be now raised upwards, a compressor tube affixed, and the front of the box and a couch or table passed under or through the stand. The tube- box can now be lowered, and compression work undertaken as with an Albers - Schonberg com- pressor. If the tube-box be rotated a half-revolution, then the patient can be brought close up to the diaphragm, and on the other hand tele-radiographs can be accurately made with the aid of a simple centering arrangement provided with the apparatus. The Wenckebach Screening Stand is somewhat different, and is con- structed for screen examinations and exposures from the screening position only. It is, however, an excellent stand for those specialising in screen examinations. It is constructed in two units. One unit might be called the screen unit and the other the tube-box unit. The former consists of a frame carrying the fluorescent screen and plate-holder, which fits into a parchment frame marked with divisions, so that a note can be made of the exact position, and an examination repeated. This frame and screen is counterbalanced, and can be easily raised or lowered in a large upright framework. On the back of this framework are fitted at convenient intervals bands for passing round the patient to keep him in a fixed position. There is also a lamp which throws a light on the scales of the second part of the apparatus. The latter or second part consists of a large protective-lined tube-box, mounted on a frame which is carried on a second upright framework, and from this project forward, one on either side, two long arms with convenient wheel handles, one on the left-hand side for raising and lowering the tube-box, and one on the right for moving it across from side to side ; also close beside the latter are the two flexible cables and handles for controlling the aperture of the diaphragm. This second part is mounted on rails laid in the floor, and the object of the long arms is that the operator, while maldng his screen examination, can push the tube further away, or draw it nearer the patient UNIVERSAL PROTECTIVE STAND 73 with the utmost comfort and ease. A stool can also be provided to support the patient if necessary. Fig. 74, — Wenckebach .screening stand. (Siemens.) Fig. 75. — Wenckebach screening (Siemens. ) Universal Safety and Protective Tube-stand. — The demand for a universal apparatus is increasing as the real importance of the Rontgen examination of the internal organs is recognised. There are, of course, various devices for radiographing the patient in a standing or sitting position, but a simple and handy universal apparatus for both fluoroscopy and radio- graphy is much to be desired. The desiderata of such an apparatus are many. The most important of .these are the fixation of the body, the straightness of the trunk, and the accurate adjustment of the normal ray to any desired point on the surface. In addition, any such apparatus, if it is to be universal, must be equally efl&cient when the patient is reclining, sitting, or standing, and should be easily adjustable for tele-radiography up to a distance of 2 metres or more. Finally, it should be capable of being easily and quickly handled, and it should not be too expensive. First, as to the straightness of the trunk. It is absolutely essential that this should be as accurate as possible for exact radiography, and for locaUsa- tion and measurement of the internal organs. Straightening by the eye is quite inadequate. The difficulty may be overcome satisfactorily by a mechanical device which carries out this straightening automatically. The trunk is often moved during the exposure, even by intelligent patients, and the picture thereby spoilt. This difficulty is partially overcome by in- stantaneous exposures of one-hundredth of a second or less ; but, never- theless, an efficient means of holding the patient is absolutely necessary since no movement should take place between the completion of the adjust- 74 KADIOGEAPHY ment of the part to be radiographed and the exposure of the negative. Moreover, it is of importance to minimise to a certain extent the costal and abdominal respiratory movements, especially in the radiography of the kidneys. The apparatus shown in Fig. 76 is constructed from this point of view. It consists of a heavy base and framework, with a well-protected tube-box, which can be moved in all directions, the fluorescent screen being suspended by cords and counterpoises. There is in addition a special tube adjustment, and a set of rails and a small table for distance radiography. The fixation board, which will take a plate-holder of any size, is furnished mth three pairs of padded clamps, each pair being moved by the simple turn- ing of a single handle, so that they are always at the same distance from the middle line of the board. The upper pair are made in the form of well -padded shoulder- caps, inclined in such a manner that, when brought together, they hold the patient's shoulders firmly, and at the same time press them against the plate- holder. To the top edge of the board is attached an adjustable support for the chin. Between the two lower pairs of clamps is a broad compression band, which can be readily tightened up by turning a handle. Another handle can raise or depress the plate-holder, so that even after the fixation of the trunk the plate may be brought to any re- quired height, or depressed as much as 20 centimetres below the board, for radiography of the pelvic organs. In the centre of the supporting board is a large opening for the diaphragm tube, for use in radioscopy. There is also a receptacle for small cross-shaped lead labels, backed with plaster, which can easily be attached to any portion of the skin. For radiography in a reclining position the fixation board may be detached from the framework. As it weighs only 40 pounds, it can easily be carried by one person, and placed on the X-ray table or ambulance. The framework is 6 feet high, and is mounted on castors. It is provided with a small wooden frame with counterpoises, which is easily adjustable by means of a hand-wheel at the back. This carries the fixation board and clamps, and the guide rails for the tube-box and fluorescent screen. Fig itaud. 7tj. — Auseful forui of universal exauiiuin (Siemens. ) This combines nearly all the movements that are necessary for a complete examination, and is efficiently protected. USES OF THE UNIVEKSAL STAND 75 For radiography of the stomach, the fixation board may be brought forward in an inclined position by means of two hinged wooden flaps. The tube-box travels along the guide rails by means of an endless screw, and can be moved vertically as well as horizontally. The trolley which carries the spindle is locked in the central position by a spring, thus giving at once the position in which the focus of the tube and the normal ray are in line with the centre line of the fixation board, and therefore with the axis of the patient's body. The guide rails are graduated so as to give the exact distance of the focus from the plate. The tube is centred once for all by means of an adjustment tube attached to the diaphragm. It is supported in its wooden box by a wooden screw and three pads covered with felt. The focus-tube adjuster is a tube at right angles to the plate and the body of the patient. This is moved about by a special sHde till its aperture coincides with a point on the surface of the body which has previously been marked by a lead label. In order to focus the central normal ray, this tube is adjusted till the lead label coincides with the crossed threads in the tube, reflected by a small mirror, and viewed through a lateral eyepiece. The tube-adjuster is thus in every position perpendicular to the plane of the photographic plate, and its extremity is always exactly 50 centimetres from the plate. At the side of the tube-box is a spring tape-measure, by means of which the exact focus distance, up to 2 metres or more, may be determined. The fluorescent screen is suspended by cords and counterpoises, and moves up and down in exact correspondence with the tube-box. Its move- ment is effected by means of a hand-wheel at the back of the apparatus. For distant radiography the rails are attached to the foot-board, and a small table on three wheels placed on the rails. The tube-box is unscrewed from the spindle, and fixed in a slot in the far side of this table. The principal uses of the apparatus are : 1. Radioscopy of the internal organs, under absolutely constant con- ditions, 2. Distant exposures (2 metres) with the patient vertical or horizontal. 3. Radiographic exposures of all kinds (universal tube-stand). The examination of the internal organs may be made in the rechning, standing, or sitting positions. In order to straighten and fix the trunk, it is advisable, first, to bring the shoulder-caps in light contact with the shoulders, and then to lower the whole fixation board, with the attached overhead rails, firmly on to the shoulders, so that they are exactly at the same height. The handle is then turned until the shoulders are firmly pressed back against the plate-holder. When placed against the pads, the patient will naturally assist the adjustment by moving towards one side or the other, until the pressure of both sides is sensibly equal. The trunk itself is pressed against the plate, by tightening up the compressor band by means of the fourth handle. After the patient has been fixed, the plate may be brought into the best position by turning the handle. The next thing is to mark with a lead cross the point on the surface of the body which has to be f ocussed, and the 76 RADIOGKAPHY centering tube is brought into immediate contact with this cross. Since this little focussing-tube is exactly in the centre line of the apparatus when held by the spring catch on the transverse rail, the centre line of the body — for instance, one of the spinous processes — must be brought into line with the tube by slightly turning the trunk. The tube may now be run back to the required distance as measured on the guide rails, and the normal ray remains accurately adjusted with regard to the specified point on the surface of the body ; it may easily be readjusted at any time if required. For long exposures the tube-box can be kept more steady by supporting it also on the small table. With a little practice the whole process of straightening the trunk and fixing it, together with focussing and bringing the ray vertically on to the plate and determining the distance of the tube, can be performed in under one minute. For a " standard exposure," the question of the distance of the focus- tube from the plate is of the greatest importance. This " focus distance " should be constant. It is a matter of some difiiculty to determine whether to make the " standard exposure " a short one, getting a sharp picture, but with considerable distortion ; or whether to make it a distance exposure, say at 2 metres, with Httle distortion, but faint and often with hardly satisfactory definition. Apparently, there is only one solution of the problem at the present time — namely, to have two " standard focus distances " : 70 centimetres for near exposure, and 2 metres for distance exposures. The advantage of telerontgenography as avoiding distortion admits of little doubt, but this is of slight service at present, when such exposures are very seldom successful. The principle of the " standard exposure " necessitates conditions which are easily reahsable by any one, viz. a near exposure of 70 centimetres. Such an exposure may now be made satis- factorily in a very short time. The focussing for a " standard exposure " can be carried out suitably once for all on the axis of the body, in which case the distortion of any internal organ, such as the heart, in the region of the centre line, is extremely shght. There remains a distortion of the con- tours towards the periphery. Alban Kohler and others have shown that the displacement of the image of the left edge of the heart is greater by 1 centimetre with a focus distance of 70 centimetres than with a focus distance of 2 metres. This error of 1 centimetre need not cause any per- plexity so long as it is constant, and in proportion to the whole thorax picture and to the surface landmarks. If, for example, we have projected on the plate the mammillary line, a radiogram taken under similar conditions will always show the outer edge of the heart in a definite relation to this line and to the outer boundary of the thorax. The same holds good for disten- sion of the aorta and for other departures from the normal. One can there- fore make a diagnosis from the plate alone, on the assumption that the exposure is a " standard " one. The distance of 70 centimetres is recom- mended because it strikes the mean between distortion and good definition in the negative. The tube-director of the apparatus is adjusted for this " STAND AED" EXPOSURES 77 focus distance of 70 centimetres, so that no measurement whatever is neces- sary. Moreover, a locking device is attached to the guide rails at 70 centi- metres, so that the standard distance is oVjtained automatically. Finally, in order to give an indication on each plate that the " standard exposure " has been given, the position of the normal ray is indicated on each plate by the projection of the lead label on the specific " landmark." This is a check on the whole adjustment, and at the same time a characteristic sign of the particular normal exposure in question. As these anatomical points are constant for each region, they serve the purpose much better than the umbilicus usually employed, which is seldom selected as the focussing- point, and consequently varies in the position of its projection. The following are the specific normal points, or Rontgen landmarks, for the examination of the internal organs. They are all on the median line of the body. Standard Points on the Median Lines at Various Levels. Chest: 1. The xyphoid process (anterior position). 2. The line between the angles of the scapulae (posterior position). Abdomen : 3. Line between the spines of the ilia (anterior position). 4. Line of the iliac crests (posterior position). Pelvis : 5. The lower edge of the symphysis pubis. 6. The tip of the coccyx. The landmark for the " standard exposure " of the hip- joint is the centre of Poupart's hgament. This is the only landmark which is not median. A flexible ruler is supplied with the apparatus, which renders it easy to obtain the exact position of the adherent lead disc, by marking on the skin the intersection of the median line with the transverse line. Such anatomical points or landmarks have, however, the disadvantage that they cannot in every case be accurately determined, and are not always quite constant. With the Universal Apparatus, therefore, a set-square is supplied, which gives the Rontgen landmarks without further measurement. By a very simple device the distance from the shoulder to the crest of the ilium is measured, and divided into three equal sections. The upper division gives the level of the Rontgen point for chest exposures, and the lower division for stomach exposures, whether dorso-ventral or ventro-dorsal. These points are absolutely constant and easy to determine. When reference is made to a " standard radiogram " of an internal organ, the first thought is of the heart, as the great aim of X-ray technique has always been to provide an accurate and useful picture of this vital organ. When it was impossible to reproduce the actual size of the heart, and even pictures with a similar amount of distortion could not be obtained, the orthodiagraph was devised to provide a tracing of the organ from a number of isolated points. At that time exposures of the internal organs were considerably below the present standard. By making an 78 RADIOGEAPHY orthodiagram one obtained, at any rate, a dotted normal projection of this organ, even although it was influenced somewhat by the personal factor of the operator. There were in addition several sources of error due to the process and to movements of the patient. All these dis- .advantages are avoided by the use of the modern rapid exposure with reinforcing screen. Moreover, it is difficult to take an entire orthodiagram during the same phase of diastole, and the drawing, which requires some time to make, often shows one part in diastole, another in systole. The tracing, therefore, often affords a much less accurate diagnosis than the photograph in which we have the united product of diastole and systole, and the contours are constant, and in their true relation to the margin of the thorax and other landmarks. By means of the small adjustable sector, it is easy to determine on the plate the constant line midway between the axis of the body and the outer edge of the ribs at the level of the diaphragm. The normal heart does not project beyond this hne, and its margin forms n definite angle with the axis, which may be measured by the diagonal of the instrument. If now the sector be laid on the patient's chest, and the constant middle line is displaced 1 centimetre inwards, so as to correct for distortion of the shadow, we may draw the actual size of the heart on the skin, and check it by the image on the plate. In any case, this so-called " constant middle fine " provides a landmark which is much more trustworthy than the extremely variable mammillary line. This constant line may be easily determined by using the sector. In conclusion, we would draw attention to the importance of the " stand- ard exposure " for examinations of the intestinal tract, where we have often to make a series of successive exposures of the same patient. An accurate comparison is impossible, except when the pictures have been made under exactly similar conditions. Further, it is of the greatest importance to know precisely the position of the pylorus, the fundus ventriculi, and the transverse colon. The possibility of incorrect diagnosis in consequence of variable •adjustments should be altogether excluded. Universal Examining" Chair. — This chair is used chiefly for screen work and for superficial radiographs. The chief object in view in the design rof the chair is to obtain as exact and as reliable a fixed position for the patient as possible. This is obtained by two wide straps fixed to the sail- cloth back of the chair, which hold the patient in an upright position, and by two easily adjustable axle supports, which prevent any movement sideways. 'The feet are well supported by a footstool, which may be adjusted to any ieight. When taking screen observations of the stomach, the seat can be leplaced by a bicycle saddle, which is better suited for this work. In order that the observer can undertake the examination of these parts in the most comfortable position, and without bending, it is necessary, -after fixing the patient, to bring him to the height desired by the observer. This is attained by an oil pump which is built into the very massive base of the chair, and which is operated by pressure of the foot on a pedal. The locking of the chair takes place automatically after the foot is removed. EXAMINING CHAIR 79 The fluorescent screen necessary for observation is secured by a holder fixed to the arms of the chair, and may be adjusted in all directions. In addition, the screen can be removed very easily, so that it may be replaced quickly by a dark slide contain- ing the photographic plate. Should it be desired, after the examination has been completed, to bring the patient back into the original position, it is only neces- sary to depress the second small pedal in order to release the locking device. Thereupon, the chair sinks slowly into the original position, owing to the excellent braking power of the pump. The chair can be moved about easily, and may also be turned round its vertical axis with the foot, so that the hands of the radiographer need never come in the path of the rays. Rieder's Exposure Stand. — Another very useful piece of apparatus is an exposure stand, originally used by Dr. Rieder for taking radiographs, with the patient either sitting or standing. It is specially suitable for thorax, stomach, and abdomen exposures. Another valuable addition is a little protective lead-lined Fig. 77.— Examining chair fitted with mechanical screen, with an adjustable lead- .r^^'^^^'^ts to facilitate the rapid manipulation of ' _ J _ the patient. (Siemens. ) lined sliding leaf, arranged with a clamp for fluorescent screen and plate-holder. This little apparatus should be mounted on good castors so as to move freely, and it can be used for many purposes. It is constructed primarily for the protection of the operator when screening, but it can also be used for the patient to stand against, and to support himself whilst being radiographed. It can be used in conjunc- tion with any X-ray couch, screening-stand, or tube-stand, and also if a long therapeutic appHcation has to be made this screen can be placed between the operator and the tube, so that no radiation from the latter falls on the operator. THE ARRANGEMENT OF APPARATUS In a work of this size it is difficult to deal adequately with so wide a subject, but for practical purposes it will be sufficient to describe : (1) A small installation. (2) An installation for a general hospital or consulting radiologist. (3) An installation for a special hospital. (4) An installation (a) for a hospital for military service, (6) for field service. Each scheme will be capable of modifications according to local demands, but the basis of each should form a working nucleus upon which the individual operator may build a complete scheme. A scheme for the arrangement of apparatus and a system of dealing mth photographic details will also be included. A system of filing negatives and reports should be adopted in every department. 1. A Small Installation There is a demand for small installations to meet the needs of practi- tioners desirous of examining their cases in the course of ordinary consulta- tion, of school clinics, especially those where treatment is carried out, and where occasional radioscopic examination is required, and finally of small hospitals, where for various reasons an elaborate installation is not possible. A comparatively large coil (say 15-inch spark-gap) is desirable. Further, a simple control apparatus is required, either mounted on the wall or pre- ferably on a wheeled trolley ; and a mercury interrupter, with dielectric of paraffin or preferably of gas ; when rapid exposures are desired, an electro- lytic interrupter should be added, and this necessitates a change-over switch in the control apparatus. In order to suppress reverse current, an adjustable spark-gap, introduced in the secondary circuit, is sufficient where small currents are used ; while for heavier discharges, obtained by using the electrolytic interrupter, valve tubes are necessary. A suitable tube-holder, with efficient protection and with the necessary fittings for therapeutic work is required, viz. tripod for treatment of ringworm, pastille holder, filters, etc. A simple examination-table with three-ply wood or canvas top, and a simple screening-stand are requisite. A vellum window may be fitted into a wooden frame which can be moved to any portion of the couch. This allows practically all the rays to pass through to the fluorescent screen, and gives the maximum value in screening. These may be combined in an apparatus which may be used for either purpose. A fluorescent screen, 80 ARRANGEMENT OF APPARATUS 81 protected with lead glass and provided with hand-guards, a supply of X-ray tubes, X-ray proof gloves, Benoist radiometer, oscilloscope tube, milliamperemeter, and photographic plates are also necessary. When instantaneous exposures are to be carried out, a casette for plates with an intensifying screen must be added. SijiniermeteT Fig. 78. — Aconveuient form of apparatus arranged on an upright cabinet. (Watson.) Fig. 79.— To illustrate the parts as arranged in Fig. 78. Portable Apparatus.— This may take the form of a trolley outfit in a compact cabinet, capable of being wheeled from ward to ward, and obtaining its current supply from the electric mains. For work in private houses or institutions unprovided with electrical installation, it is necessary to have an outfit which derives its current supply from accumulators. Essentially it is the same as the small installation described above, but a 12-inch coil is for various reasons more convenient. A mercury-interrupter of the " Sanax " type is convenient ; a tube-stand of lighter construction and a portable examination table may be added. The connections of the 82 RADIOGEAPHY accumulators are illustrated in the accompanying diagram. When exposing plates with a portable apparatus, a casette and intensifying screen should be used, as these greatly shorten the length of exposure. 2. Installation for a General Hospital or Consulting Radiologist The essential features of a somewhat more complex installation may be briej&y enumerated. (a) One or more coil outfits, with, where possible, a powerful instrument, such as a high-tension rectifier, a Snook machine, or a powerful coil outfit fitted with three breaks (mercury with gas dielectric, triple Wehnelt, and, if possible, a single-impulse switch). With a high-tension rectifier apparatus one can add a single-impulse switch. (6) A second outfit of less capacity is useful as a stand-by in case of a break-down. This is an important point, because in a large institution work must go on constantly. (c) Overhead high-tension cables, properly insulated, should be stretched from one end of the room to the other. {d) A change-over switch is useful when two installations are used, and another switch for quickly connecting to various pieces of apparatus. This may also be accompanied by adjustable tube leads, running on wheels along the high-tension cables. The plan shown on p. 83 illustrates the best arrangement of apparatus when one room only is available. The various pieces of apparatus are marked on the plan. The dark room should be in close proximity to the X-ray room, but care should be taken to ensure thorough protection of the unexposed plates and papers. For large institutions a suite of rooms is necessary. The plan on page 84 shows the arrangement of rooms at King's College Hospital. The rooms are marked according to the use they are put to. When a separate building is available, it can be specially planned to meet the requirements of the institution. Should it be necessary to plan an X-ray department, great care should be paid to the arrangements of the radiographic room. The fighting of this room should be carefully planned. A large window means that trouble will arise when it is necessary to darken the room, consequently the smallest possible window space must be allowed. The radiographic room must be large. It should have in close proximity to it a waiting-room, one or more dressing-rooms, and a preparation-room where patients may be anaesthetised or an opaque enema administered prior to taking the patient to the radio- graphic room. This room should have an adequate supply of hot and cold water and other conveniences. These additional rooms should open into the radiographic room. Doorways should be wide enough to allow of the passage of a large trolley. 83 84 EADIOGRAPHY Fig. 81. — Plan of the X-ray and electrical departments at King's College Hospital. (By kind permission of W. A. Pike, Esq., F.R.I.B.A.) The cubicles marked "electrical treatment" are fitted with X-ray installations. The room marked " dressings " has since been fitted up as an operating-theatre for electro-coagulation and for operations for removal of foreign bodies under X-rays. INSTALLATION FOR A SPECIAL HOSPITAL 85 3. Installation for a Special Hospital The plan of an Electrical Institution is shown on page 86 ; this building was specially planned for the purpose, and is quite complete in details. The ground floor contains a waiting-hall with lavatory accommodation, a small consulting- room with dressing-rooms, — the former fitted \nth. a desk, filing cabinet, and examination lamps, etc. The Radiographic Room. — This contains the large single-impulse apparatus, with the regulating apparatus in a lead-lined protection cabinet. A couch and screening-stand form the chief accessory apparatus. Cupboards for tubes, etc., form part of the furniture of the room. There is a viewing- box, to take two 15 by 12 negatives, a stereoscope, and a large viewing-box, to take six 15 by 12 plates, each with removable fronts, adapted to hold smaller plates. Two dark rooms adjoin the radiographic room. The inner dark room is fitted with the viewing apparatus, which will be described in detail later. The First Floor. — This is devoted to radio- and electro-therapy, and has, in addition to the special X-ray treatment cubicles, cubicles for carbon- dioxide snow work, radium treatment, diathermy, the mercury vapour lamp, Schnee four-celled bath, and galvanism and faradism. A feature of this room, and also of one at a general hospital, is a small room fitted as an operating-room for diathermy, electro-coagulation, and operations for the removal of foreign bodies under X-rays. A photograph of one of these rooms is shown on page 266 to give some idea of the arrangement of apparatus. The Dark Room. — When a large amount of work has to be got through it is necessary to have a large and well-equipped dark room, with possibly an outer dark room. This should contain cupboards for plates, papers, etc. A reducing lantern is useful for the supply of reduced prints, lantern sHdes, etc. The dark room should be carefully planned to facilitate speedy work- ing. The entrance should be carefully guarded by two doors with an interval between. It is an advantage to have them so arranged that the two cannot be open at the same time. Shelving and cupboard accommodation should be provided. The ventilation should be good, and the heating of the room should be carefully attended to. Several fights are required : (a) Two or more ruby lights ; (6) a yellow fight for printing, etc. The development should be arranged for at one end of the room, a capacious sink with a good supply of hot and cold water being provided. Next to this is placed a washing tank, then a fixing tank or tanks, and lastly another washing tank. These should all be large and deep. A drying rack should be placed at this end of the room, and a viewing-box for inspection of the negatives when wet. Plates and papers should be kept in a cupboard at the opposite end of the room, if an outer dark room has not been provided. In the largest hospitals the organisation of the electrical department becomes more involved. It is only when the whole department is under 86 RADIOGEAPHY efficient control that good work can be turned out in a routine manner. The efficiency, therefore, of such departments depends on thorough organisa- tion more than on individual effort. All the workers must be trained to :^ Fig. 82. —Plans of the electrical department at the Cancer Hospital, Fulham. (By kind permission of E. M. Pole, Esq.) perform their particular part of the general whole in the most efficient manner possible. X-RAYS IN MILITARY SERVICE 87 4. Installation for a Hospital for Military Service Equipment for Military Radiography. — Radiography has been found to be of great use in the detection of fractures and foreign bodies. Its value therefore in the medical equipment of the military service is beyond doubt. Thorough equipment and organisation are necessary to obtain the maximum value, as it is often a matter of great difficulty to deal in the most efficient manner wdth the large amount of work which at times presents itself. The ideal scheme is one which is simple, com- prehensive, and efficient, and this entails much prehminary detail work. An efficient scheme, and one which commends itself, consists of : (1) An installation at a base hospital, (2) a serviceable installation at a collecting hospital, (3) a portable outfit for use on the field. (1) The equipment at the base hospital should be complete in every detail, because it is here that very important work must be thoroughly and expeditiously carried out. The question of staff depends on the amount of work required, but the equipment suitable for a general hospital is suitable for such a base hospital. The advantages of a thorough equipment are other than purely radiographic, as it can be used as a training school where medical men, nurses, and orderHes can receive appropriate instruction in all branches of the work. Also it is here that cases requiring very careful investigation and exact localisation can be referred from the collecting centre. (2) The Collecting Hospital. — This outfit should be more or less a stationary one, with ample conveniences for photographic work ; but at the same time the apparatus should be arranged to allow of quick transport from place to place when the forces are moving rapidly. The following apparatus should place a useful outfit in the hands of the radiographer: (1) Electrical Supply. To obtain the necessary electrical supply the choice lies between (a) accumulators and (6) petrol engine and dynamo. The latter is undoubtedly the better, though it is a good plan to include a set of accumulators which can be charged from the dynamo. The petrol engine and dynamo are mounted on a combination bed-plate ; a magneto ignition carburettor fuel tank and radiator should form part of the set. At a speed of 700 revolutions per second the apparatus should generate 1 kilowatt or 100 volts and 10 amperes. The whole should be completed with shunt regulator switch-board for charging accumulators, and there should be a radiator for cooling purposes. This set should be arranged for direct connection to the X-ray apparatus. (2) A set of portable accumulator batteries consisting of six cells and 50 ampere-hour output. (3) A 12- or preferably a 15-inch portable coil with subdivided primary with a condenser and a small moto-magnetic interrupter ; this will be found useful as a second break when the larger one is out of action. The coil should be fitted into a strong outer wooden case for transport. (4) The interrupter should be of good size, and one of the many mercury jet interrupters will be most suitable. The motor should be KADIOGEAPHY wound to work at 100 volts on direct current, which is derived from the petrol electric set. (5) A small switch-board and rheostat with the auxiliary control switches should be included. This may be arranged in the form of a box, which, when closed, allows of ready transport. (6) A simple tube-stand with mechanical movements is necessary. It should be readily taken to pieces if required. (7) An X-ray couch. This should have folding legs, and should be light and fairly rigid. It should be constructed so as to allow of screening. (8) X-ray and valve tubes. It is well to have a good supply of these. When it is necessary to have the installation removed to another base they should be packed in large boxes, and should be suspended from the top or sides of the box so that they may not easily be broken in transit. Three to six tubes will form a good set for ordinary use. (9) A fluorescent screen fitted with Interrupter Battery Coil in cabinet Fig. 83. — Portable X-ray installation arranged for radiography from beneath couch. lead glass and protective rubber handles. Also several pairs of lead-lined gloves will be necessary. (10) Intensifying screens with casettes. A simple form of localiser should be included. Photographic conveniences : these must be left to the calls of the particular place the installation has to serve. When a dark room is not available it must be provided for. A small dark room may be constructed of wood built in sections, or a tent may be requisi- tioned. The fittings should consist of lead-hned benches, with sink and waste pipe. A water-supply can be connected to the sink if such is available. A good supply of flexible tubing will be found useful when water has to be brought from a distance. A dark-room lamp with a safe light should be included. A candle will give sufficient illumination. (11) Developing dishes of sizes up to 12 inches by 14 inches, also draining racks, etc. (12) A supply of X-ray plates and X-ray paper. The latter is useful when it is not PORTABLE FIELD OUTFIT 89 convenient to use plates. An X-ray paper for direct radiography has been prepared. This, though not so good as the plate, is much more convenient for transport. (13) A supply of chemicals. The tabloid developers are very useful, as they are readily made up in a few minutes. The installation may be varied according to the needs of the radiographer, the important point being to provide a high standard of efficiency, combined with the possibility of rapid movement if such be required. The efficiency will depend upon the knowledge the operator has of his apparatus. He should be conversant with the mechanical details of all parts, and should be able to pack, re-install, and get into working order quickly. Practice wdll soon enable him to do all that '-^. Fig. 84. — Portable X-ray installation packed ready for transit (Medical Supply Association). is necessary. When a large amount of work has to be done, assistance must be available. One or more medical radiographers should accompany each installation, and several orderlies or nurses must be trained to carry on the work at any time. In the case of large armies there must necessarily be several installations working at various places. To facilitate rapid work a system must be employed. The difficult cases may be transferred to the hospitals at home if the patient is in a condition to travel and the symptoms are not urgent. By doing this the collecting hospitals are reheved of heavy work, involving much time, and are able to attend to the more urgent cases as they come in. 90 EADIOGEAPHY For localisation of foreign bodies several methods may be used ; these are fully described in the portion of the book dealing with localisation. (3) The Field Outfit. — The essential is portability. The best arrange- ment for work on the field is a small but serviceable installation fitted up in a motor transport, the engine of which can be used to drive the dynamo which generates the electricity. By this means a more powerful installation can be used than when dealing with accumulators. The whole apparatus can be fitted up in a motor bus, a portion of which can be screened of? to form a small dark room. Necessary Apparatus. — (1) A dynamo, (2) mercury jet interrupter, (3) fifteen-inch coil, (4) X-ray couch with all accessories, (5) tube-stand with mechanical movements, (6) fluoroscope for screening, (7) plates, tubes, and dark-room requisites. An extremely compact and portable outfit is illustrated on pages 88 and 89. It is most suitable for field work when petrol engine and dynamo are not available. It combines portability with considerable efficiency. It consists of : (a) Set of accumulators. (6) Hand-driven interrupter, which controls the current derived from the accumulators. The method used for obtaining the required speed from the interrupters is somewhat ingenious, a cylindrical weight inside the interrupter giving the effect of a fly-wheel, and permitting a regular speed to be obtained. (c) Coil enclosed in a cabinet which is arranged to form a complete case for the whole outfit. (d) Tube-holder combined with the cabinet. The small portable set when not in use for field work may be used for radiography of cases in the wards of the hospital. There are many patients who are not fit to be moved to the radiographic room ; such cases can con- veniently be done in bed when a portable set is available. PRODUCTION OF THE RADIOGRAPH The question of exposure in radiography is one which is ever before us. How long an exposure must we give for a particular region ? Before making a statement on the question of time it is necessary to consider the various factors which govern the exposure. The Plate or Film Employed This is the first point for consideration. X-ray plates are specially prepared for radiographic Avork, and any of those on the market are good. In this country the most suitable and best know^n are those of Ilford, Wellington, Warwick, Wratten, and the Barnet. The emulsion is spread over a sheet of glass, and the plate is enclosed in two light-tight envelopes. A second envelope is used to avoid the danger of fogging when one only is employed, by accidental admission of light or through pin holes in the paper. These special X-ray plates are expensive, so when a large amount of work has to be got through, a cheaper plate may be used for the detection of fractures of the extremities. When a fine detail is not essential, as in determining the presence of a fracture or dislocation, any ordinary photo- graphic plate can be used. The plate may be placed in a special casette, in which case the black envelopes are not required. Care must be exercised in the dark room, when opening a box to take out a plate, to make sure that the light is " safe." When the dark room is in close proximity to the radiographic room, some form of protection must be employed to prevent the plates from being fogged by X-rays. A box lined w-ith several millimetres of lead will be sufficient to serve for the protection of these. Manufacturers are endeavouring to produce a plate which will be much faster than those at present in use. Exposure The length of the exposure depends upon : (1) The quality of the tube and the degree of penetration. (2) The strength of the current employed, the size and quahty of the coil, and the type and frequency of the interrupter. 91 92 EADIOGRAPHY (3) The thickness of the object. (4) The distance of the tube from the plate. (5) The rapidity of the X-ray plate. The Quality of the Tube. — The operator must know the quality of his tubes well, A hard tube should rarely be used if good radiographs are required. A soft tube will give good detail in all the parts, but particularly of the soft parts, where a diagnosis is required of their condition. For fine detail in bones it is better to give long exposures with a soft tube, and trust to the increase in the time to give the necessary detail. The Intensity of the X-rays is in proportion to the penetrating power of the tube multiplied by the number of milliamperes used. With one and the same tube, 1 milUampere for 60 seconds, or 2 milhamperes for 30 seconds, or 10 milliamperes for 6 seconds will produce the same effect on a plate. If tubes of different penetrating power are used, the number of milliampere-seconds required with a soft tube may be three to five times as great as that required with a hard one. To produce a certain density on a plate, 30 seconds' exposure with a current of 2 milliamperes may be sufficient with a hard tube, whereas with a soft one either 150 seconds may have to be given with a current of 2 milhamperes, or else 30 seconds with a current of 10 milhamperes. The next factor in the calculation of the exposure is the thickness of the subject. Chest and abdomen, for instance, may have the same thick- ness, but if the latter requires 200 milliampere-seconds, 50 to 80 milliampere- seconds may be enough for the former, because the chest contains the lungs filled with air, whereas the contents of the abdomen have a greater atomic weight. For the same reason the head requires more milliampere- seconds than the chest, though both may have the same thickness. The intensity of the X-rays is in inverse proportion to the square of the distance. While one is aware that any increase of distance means prolongation of the exposure, it is a good point to get a good distance away from the plate. The farther the distance between the anti-cathode and the plate up to a limit of about 6 feet the sharper will be the resulting radiograph. At the distance of 6 feet a natural-sized picture is obtained, with no distortion. This distance may be employed when the exact size of an organ like the heart is desired ; a good average working distance is about 2 feet for parts of average thickness. A slide rule enables us to find out the necessary exposure approximately. The first scale contains figures for the distance between anti-cathode and plate, varying from 12 up to 200 cm. On the second scale, figures for the thickness of the object, varying from 2| up to 50 cm., will be found. On the third scale is the penetrating power of the tube in Wehnelt units, from 2 up to 18 ; and the fourth scale contains the figures for the milliamperes used, and rises from 0-5 up to 50 milliamperes. By adjusting the two slides so that the figures for the distance, thickness, penetration, and current which are being used are opposite to one another, the index on the second slide points to the number of seconds required for the ESTIMATION OF THE EXPOSURE 93 exposure, which is on the fifth' scale, beginning with I and rising up to 120 seconds. On this basis it is possible to set down an Exposure Table which shall be of some practical utility to the beginner. There are of course so many special conditions that come into the matter that it is not possible to lay SCHALL » SON Bjjr Expocurts PLATS. IN CTM. M M 1! 10 5» f •? I " li? I » I : LCHSCK. M. 1 — I ill',' ['i'l'!'l',i''",i'^''i-'^''J,'"'i ' i ' i rrrr ^^ J ' 1 'i'i4'i'riv"'i""i"'ri 'i'j'i' i'L'. EXPOSURE IN SECONDS Fig. 85.— Slide rule. down hard and fast rules. Actual experience with the outfit and tubes is essential, combined with the exercise of good judgment. The following table will therefore only be taken as a guide, remembering always that if the tube be softer or the distance greater the exposure must be corre- spondingly increased. The exposure must also be increased for abnormal stoutness, and so on. Above all, each focus tube, no matter what its degree of hardness, must be worked to just that extent which signifies maximum eflaciency, neither under-running nor overstraining. This point is dealt with fully in the chapter on Tubes. Object. Distance from plate to anti- cathode. Penetration. Wehnelt Scale. Benoist and Bauer. M.A. Seconds. Skull, occipito-frontal Skull, transversely .... Skull, teeth (with film inside) . Cervical vertebrae .... Shoulder . Thorax Lumbar region Abdomen Ribs Knee-joint Femur Ankle and foot Wrist, hand Stomach (Bismuth meal) . Kidney Pelvis Hip-joint Heart Lungs, diagnosis of early tuberculosis Inches. 18 18 15 18 18 18 18 22-28 22 22 18 22 18 24 18 24 24 24 22 9-10 6-7 9-10 6-7 8 5 8-9 5-6 7-8 5 7-8 5 8-9 5-6 8-9 5-6 8-9 5-6 8 5 9 6 6-7 4-5 6 4 9-10 6-7 6-7 4-5 9-10 6-7 9-10 6-7 9 6 6-7 4-5 90 140 15 70 80 80 180 75 75 70 90 30 12 100 180 200 150 45 100 The above exposures are calculated without intensifying screen. If a screen be used, the exposures are reduced to about x^th or y^th. Rapid radiographs in one or two seconds, or even fractions of a second, M RADIOGRAPHY are secured by powerful intensified coils of, say, 16-inch spark length running with centrifugal motor mercury interrupter, utilising a heavy primary current, and in conjunction with a good heavy-anode tube that has been well tuned up. After practical experience, and after becoming a thorough master over the peculiarities of his own outfit and his own focus tubes, the beginner will soon find that he is able to reduce exposures very considerably all round. With a single-impulse apparatus radiographs of the chest may be obtained when an intensifying screen is used in y^ of a second. The more recent forms of this apparatus enable the worker to obtain good radiographs of stout patients in this time. For the abdomen the output of the apparatus is not sufficient to produce good results. In such instances recourse must be had to comparatively short-time exposures. With an automatic cut-out switch tV or ^ of a second may then be sufficient. The aim of all workers is to produce instantaneous radiographs without the use of the intensifying screen. The Coolidge tube, with its capacity for passing heavy discharges, jnay be a means to this end. ExposTJKE Tables Comparison of Different Radiometers Benoist .... 2 2* 3 4 5 6 7 8 9 10 Benoist-Walter . 1 2 3 4 4* 5 5^ 6 Walter .... 2-3 3-4 4-5 5-6 6 6-7 7 7-8 Wehnelt 1-8 3-3 4-9 6-5 7-2 8 9 10-5 13 15 Bauer .... 1 2 3 4 5 6 7 8 9 10 The Intensity of the X-rays varies with the Distance between Anti-cathode and Plate or Object. — The intensity of the X-rays is in inverse proportion to the square of the distance. If we have to expose for a certain object 3 .seconds, with a distance of 10 inches between the anti-cathode and the plate, the time of exposure required with will be 10 12 16 20 25 30 40 50 60 80 inches 3 4-32 7-68 12 18-75 27 48 75 108 192 seconds ■or, expressed in other figures Distance Exposure 10 10 14-1 20 17-3 30 20 40 22-4 50 24-5 60 26-4 70 28-3 80 30 cm. 90 M.A. seconds. 'The distances usually chosen are : For teeth, toes, fingers, or hands Arms, neck, leg, or foot Nose, head, shoulder, knee . Chest, kidney, pelvis . 10 to 12 12 „ 15 20 „ 22 22 „ 25 inches. The distances given are approximate only. When the subject is fairly thick, it may be necessary to have the tube at a greater distance ; also, when the object from a diagnostic point of view is likely to be obscured by shadows thrown by structures in front of it, it will be found advantageous to have the tube close to the surface of the body. PHOTOGRAPHIC TECHNIQUE 95 Caution The distance chosen depends upon the thickness of the subject. At the longer distances we must employ apparatus of varying power, such as an intense single-impulse coil, or one of the forms of high-tension rectifier. The additional advantage of working at long distances from the tube is that both the patient and the person screening are less likely to be damaged by the X-rays. Care must be increased when working at a short distance, especially when repeated examinations of a particular patient are required, that the patient is not damaged. If work must be done at a close range it is wise to have in front of the tube a screen of aluminium 1 mm. thick. This does not cut oii any of the penetrating rays, but retards the softer ones, which are likely to damage the skin. The exposure times given on page 94 are only approximate, and should not be taken as an absolute guide. They illustrate the principle of exposures rather than the practice. Conditions vary with different apparatus, conse- quently the operator must clearly understand his outfit, particularly the X-ray tube. When very rapid exposures have to be made the difficulty of accurate work is increased, there being no great latitude upon which to work. Single-impulse exposures, when an intensifying screen is used, are com- paratively easy, but even here the correct condition of the tube must be obtained if perfect radiographs have to be produced. A tube a trifle too hard will give an over-exposure, while a soft tube will give an under-exposure. It is possible that when tubes constructed on the principle of the Coolidge tube come into general use, the technique of exposure will require to be largely remodelled. The Adjustment of the Radiographic Plate For X-ray examinations a special plate is employed. It is made more sensitive, and gives greater detail by reason of a thicker emulsion, containing more silver salt than the ordinary photographic plate. The plate is placed in a casette or two light-proof envelopes in the dark room, the film side of the plate being placed towards the object to be radio- graphed. The centering of the plate is a matter of some importance, most modern couches having devices by which this may be done automatically. The best method of centering is one devised by Dr. Ironside Bruce, where the central ray from the tube can always be located by means of a plumb-line operating over the top of the couch. This may also be used for getting the centre of the plate exactly in the centre of the part to be examined. The part of the patient to be examined should always be as close to the plate as possible. On the couch some form of compression must be employed to keep the parts as quiet as possible. When the screening-stand is used, the part is first examined by the aid of the fluorescent screen, and 96 EADIOGRAPHY the diaphragm adjusted to cover the part required. The fluorescent screen is replaced by the X-ray plate in a casette and clamped in position, and the patient may be fixed by a strong linen band or a bandage. The shorter the exposure the less risk is there of movement on the part of the patient spoiling the result. The Use of the Intensifying Screen Though negatives obtained by the use of the intensifying screen may not perhaps be of the same high technical quality as the best radiographs Fig. 86. — Normal hand to illustrate value of an intensifying screen. (a) An intensifying screen was used for this (b) Taken without an intensifying screen with ten radiograph, the exposure being yV "^f that for (b). The radiogTaph was considerably over-exposed. times the exposure. Note the detail in soft parts. made by powerful installations without a screen, it should be noted that when skilfully used, pictures so obtained with apparatus of moderate power are, from a diagnostic point of view, of much greater value than those obtained without a screen. This is especially the case when radiographing parts of the body where movements are constantly going on, as in the chest and abdomen. The plate must not be over-exposed, otherwise grain, due to contact with the screen, is bound to appear. A soft tube also is necessary when the screen is used, and it should be noted that there is not quite the same degree of latitude in the matter of exposure, but when all conditions are correct, radiographs so obtained can hardly be distinguished from those taken without the aid of the intensifying screen. This applies not only to the plate, but more particularly to the print, and a little experience with an DEVELOPMENT OF THE PLATE 97 average installation of moderate power and a screen will soon teach anyone how to obtain valuable diagnostic negatives, and enable the operator to do quick work, which would otherwise be beyond his reach. For the purposes of diagnosis in regions such as the heart, lungs, stomach, or intestines, the value of radiographs so obtained cannot be overestimated, as with any of the modern intensifying screens it is quite possible to get results showing practically no grain. It is most important that every care should be taken to avoid damage to the delicate surface of the screen, because any scratches or other markings causing an abrasion of the surface will certainly be produced on the negatives. Before placing the screen in the holder it should be carefully dusted with a wide camel-hair brush. The film side of the plate is brought into contact with the fluorescent coating on the screen, care being taken to avoid rubbing the surfaces together. When making the exposure the film side of the plate should face the X-ray tube. When the screen is not in use it should be placed in such a position that it cannot get damaged or splashed with chemicals. The value of an intensifying screen is illustrated by the figures on the opposite page. Development The general description of the dark room has been given in the chapter on the arrangement of apparatus, etc. It is essential to take the same care in the development of X-ray plates as is necessary in developing the fastest of ordinary photographic plates. Specially prepared X-ray plates are slightly sensitive to red light, and care must, therefore, be taken to avoid more light falling on the plate during development than is really necessary. This can be accomphshed in the following ways : 1. The employment of a carefully tested " safe-light " glass in front of the source of illumination. This screen must be tested in the conditions under which it will work ; thus, if electric light is used, a bulb of the same candle-power should always be used in the lamp. 2. The electric bulb may be immersed in a solution coloured by bichrom- ate of potash and an aniline dye. To ensure greater safety the globe con- taining the lamp should be covered with a layer of yellow and ruby fabric. Provided exposure is not unduly prolonged, the X-ray plates may be developed in this light. The dark room lamp should have in a convenient place a switch in order that the light may be turned off when developing the plate. 3. A cover to fit the developing dish may be placed over it immediately the plate is immersed, and not removed for several minutes, as it is in the early stages of development that plates are most easily fogged. 4. The plate may be developed in the dark. The Choice of a Developer. — Any properly balanced developer can 7 98 EADIOGEAPHY be used, the majority of workers using that recommended by the makers of the plates. Of these (1) Metol-hydrokinone, (2) glycine, (3) rodinol, (4) pyro-soda are the most commonly used, and each has its own advocate. The formula for one of the most largely used — ^metol-hydroldnone — is : — Metol, 20 grains ; hydrokinone, 80 grains ; sodii sulphite (crystals), 2 oz. ; sodii carbonate (crystals), 2 oz. ; potassii bromide solution (10 per cent.), 80 minims ; water, 20 oz. The Preparation of the Developer. — (1) The metol must first be dissolved in 8 ounces of pure water (warm). When thoroughly dissolved the hydrokinone is added. (2) The sodas and bromide are then dissolved in a further 8 ounces of warm water, the two solutions mixed, and made up to 20 ounces. It is most important that each ingredient be allowed to dissolve thoroughly before the next is added. The developer is then allowed to cool, and to ensure the best results, should be used at a temperature of 60° F. The following facts explain the reason for this insistence on a imiform tem- perature : Metol and hydrokinone act differently on the photographic plate, metol being employed to obtain good detail, while the hydrokinone ensures density. The hydrokinone acts best at a temperature of about 65°, and becomes practically inert below 45°, and, therefore, in order to ensure that both agents act to the best advantage, it is necessary to work at about 60°. For this reason in cold weather the dark room should be kept at a little above 60°, and at a level temperature, in order that the dishes and solutions should not fall much below. In very cold weather, when plates are obtained which are lacking in density, but show fine detail, — when all other factors employed in the exposure of the plate have been favourable, and a good strong negative was expected — the explanation is often found to be a faulty temperature of the developer. Caution. — ^If the metol is not allowed to dissolve thoroughly before the other chemicals are added, it will crystalhse, and be precipitated in the form of granules. Should any of these settle on the plate during the process of development, small black spots with soft edges are Hkely to appear in those places where the granules have settled. Moreover, in using the developer improperly made up, the full strength is not available, and such conditions may account for failure to obtain the best possible results. A freshly made developer should be almost transparent in appearance and free from colour ; stale developer is from a light- to a dark-brown in colour. In hospitals and similar institutions, and with many radiographers, the practice is to have the developer made up by the chemist or his assistant, who does not understand the importance of extreme purity of chemicals and exact weighing, and so frequently sends up a hastily prepared developer which may spoil many otherwise good results. In large institutions a skilled photographer should be attached to the department, whose duty it should be to attend to the preparation of all solutions used. When specially good negatives are desired it is a good plan to have a stock solution of sodium sulphite and carbonate in the proper proportions FIXATION OF THE DEVELOPED PLATE 99 ready at hand. The metol and hydrokinone are then freshly prepared in warm water when wanted, and added as required, as is also the bromide solution. If these points are attended to, there should be no difficulty in obtaining really first-class negatives. The developing solution should not be used for more than three or four plates in succession ; if used too often it becomes oxidised by exposure to the air, and ceases to yield satisfactory results. A developer which has already been used for a number of plates should not be kept for further use. Oxidation having commenced A\ill continue until the solution ultimately becomes nearly black and quite useless. The freshly made metol and hydrokinone, if kept in properly stoppered bottles, will keep in good condition for a considerable time. With normal exposures the image appears in about fifteen seconds, and development is complete in four to five minutes ; but in cases where the exposure has been very short, the image appears more slowly, and the time of development is proportionately longer. Where instantaneous exposures have been given, such, for instance, as j}q of a second, development from fifteen to twenty minutes may be necessary in order to secure the desired results. Under these circumstances it is advisable to keep the developing dish covered over in order to avoid any possibility of fog from prolonged exposure to the dark room light during the process of development ; and the dish should be gently rocked until development is complete. The use of a weak or highly restrained developer should be avoided. Fixing After development the plate should be rinsed for at least thirty seconds before placing in the following fixing-bath : Hyposulphite of soda, 1 lb. ; potassium metabisulphite, | oz. ; water to 80 oz. If the fixing-bath is required for immediate use it is advisable to dissolve the potassium metabisulphite before adding the hypo, but hot water should not be used for the purpose. Allow the negative to remain in the hypo bath until thoroughly fixed, and on no account examine a partially fixed plate by daylight, or stains will appear on the fUm which cannot afterwards be washed out. If the plate is not washed free from developer before being placed in the fixing-bath, yellow stains will appear on the film which are very difl&cult to remove. Washing and Drying After complete fixation, the plate should be washed in running water for at least one hour, and then placed in a well-ventilated room, free from dust, until dry. If a negative is required for use immediately after develop- ment, fixing, and washing, it may be dried rapidly by the following method : 100 EADIOGRAPHY The surface moisture is first removed by allowing the plate to drain, or it may be carefully removed mth a wad of cotton-wool or a pad of fine chamois leather. It is then placed in a methylated spirit bath for four or five minutes, and rocked as in development. It is then removed, and placed in a current of air or in front of an electric fan, when it will dry very rapidly, or it may be placed in a specially arranged drying-oven. Reduction It is sometimes necessary to reduce a developed plate which has been made too dense. The following solution will be found very useful for the purpose : Potassium ferricyanide, 120 grains ; water to 20 oz. A dram or two of this is added, just before using, to each ounce of ordinary hypo solu- tion as used for fixing photographic plates, i.e. hypo, 4 oz. ; water to 20 oz. The plate is immersed in the reducer when it is to be acted on all over, or if for local use, the solution is apphed with a httle tuft of cotton- wool. The plate after reduction is well washed and dried. Intensification Negatives which are not sufiiciently \dgorous omng to some error in manipulation may be greatly improved by the process of intensification. The film should first be hardened in the following bath : Formalin, 1 part ; water, 10 parts. In this bath the negative should be allowed to remain for five minutes, after which it should be rinsed for a few nnnutes, and then placed for exactly one minute in the following bath : Potassium ferricyanide, 20 grains ; potassium bromide, 20 grains ; water to 20 oz. Too long an immersion causes the image to bleach, and this should be avoided if it is desired to retain the original gradation. In the time pre- scribed there is no apparent change, but the clearing agent has done its work, which is the prevention of green fog in the subsequent process of intensi- fication. The negative should now be rinsed for a few minutes, and then intensified in the following stock solutions : {a) Silver nitrate, 800 grains ; distilled water to 20 oz. (b) Ammonium sulphocyanide, 1400 grains ; hypo, 1400 grains ; water to 20 oz. Half an ounce of {a) should be taken and added slowly to half an omice of (6), stirring vigorously with a glass rod. Sufficient silver nitrate solution must be added until the precipitate formed is dissolved with difiiculty. To this solution should be added : 1 dram of a 10 per cent, solution of pyro preserved with sulphite, 2 drams of a 10 per cent, solution of ammonia. The negative should be placed in a chemically clean dish, and the silver nitrate solution poured over it. In a minute or two the deposition of the silver begins to take place, and as soon as sufficient density has been acquired, the negative should be placed in an acid fixing-bath until the slight pyro stain is removed. After this bath the negative should be well washed, it PRINTING FROM THE NEGATIVE 101 being well, during washing, to lightly rub the surface of the film with a tuft of cotton wool to remove the slight surface deposit which will be found upon it. It is important that the negative to be intensified must have been thoroughly fixed in a clean, fresh hypo bath, and not merely have been left for some indefinite period in a stale or dirty solution of hypo that has been used on other occasions. A useful method is to bleach the washed negative in a saturated solution of perchloride of mercury, wash well, and then place in a strong solution of ammonia. Printing The printing of au X-ray negative is an art which is too often neglected by the radiographer. A well-finished print, nicely glazed and suitably mounted, is the finished work of the expert, and should always be aimed at, slovenliness here being quite inexcusable. It must be remembered that the average plate will produce a print which will explain the conditions found, and in the majority of cases it is on the print that the radiographer is judged. Consequently it should always be the aim to tuin out a good print. The three papers commonly used in printing are : (1) Bromide paper. (2) Gas-hght paper. (.3) Silver paper. Nos. 1 and 2 are the most frequently used because of the conveniences they offer. The best prints are undoubtedly obtained by using P.O. P. paper, the difficulty being, however, that a strong fight is required, and the operator is dependent in the majority of cases on daylight conditions. When day- light is not available these papers may still be used by the aid of an arc lamp, by the use of which a negative may be printed in from ten to fiiteen minutes. The toning and fixing of papers so prepared is a fittle more troublesome than when papers (1) and (2) are employed, which possess the advantage over silver paper that they give the operator the opportunity of producing a good print by careful development, as by careful manipulation prints of good diagnostic value can be obtained from very indifferent plates. It must be insisted upon that the touching in of detail should never be practised in radiographic work. Though largely used in artistic photography, it has no field here. In hospitals and in private practice, where large plates are used and several are taken of the same subject, reduced prints may be obtained by the use of a reducing lantern. By using an apparatus of this kind it is possible to obtain in a small space prints of the largest plates. These may be mounted in series on a large mount, and despatched to the physician or surgeon in charge of the patient. These reduced positives are quite sharp, show all the detail of the large prints, and may be included in the notes of a case. Plates when dried should be carefully cleaned and particulars attached to them. When examined and reported on, they should be filed away and indexed. The card index system will be found most useful for this purpose. Special cards may be printed to suit individual requirements. 102 RADIOGRAPHY Further Points in Exposure and Development It is worthy of note that a practical knowledge of photography is very helpful to the radiographer, and in no part of his work more so than in the development of his plates. Fortunately for the majority of workers whose An exposure of 12 sees. 10 An exposure of 28 sees. 24 20 16 12 Fig. 87. -To illustrate the latitude of exposure. Each of the twelve exposures gives a good negative. These exposures were made with a moderately soft tube. knowledge of photography is slight, considerable latitude in the exposure time exists. First Experiment. — In the course of a number of experiments performed for the purpose of ascertaining this point, it was found that if a limb of even thickness was radiographed, being divided into areas which allowed of twelve exposures of different duration, commencing with 2 seconds and ranging up to 20 to 30 seconds, useful negatives were obtained from each exposure. PRACTICAL POINTS IN EXPOSURE 103 The development was necessarily uniform, as all the exposures were on the one plate. Second Experiment. — On this occasion the same duration of exposure was given to each part, and it was found that useful negatives were obtained by varying the time of development. Third Experiment. — This experiment was carried out with a view to ascertaining the influence of temperature on the action of the developing agent. A wide range of variations was found which are very instructive. Using the same exposure for two plates and developing them side by side, one solution being about 20 per cent, colder than the other, it was found that at a temperature of 60° development was rapid, detail good, and density Exposure 2 seconds. Fig. 88. — To illustrate the latitude of exposure. Exposure with a hard tube. correct. If the temperature was below 45° the resulting picture showed detail, but httle density, indicating that the hydrokinone had not been able to use its influence. Fourth Experiment. — On this occasion variations in exposure were made, the times of exposure being as 1 to 5. The plate exposed for the shorter time was developed at 60° and the other at a low temperature. It was found that the first plate gave the better result. These experiments indicate that by giving minimum exposures the wear and tear on apparatus and tubes is lessened, and the fogging of plates by secondary radiations avoided, while by proper manipulation of the developing solution better pictures are obtained. A further advantage of using the 104 KADIOGRAPHY developer at a proper temperature is that we lessen the risk of fogging the plate bv prolonged exposure to even a " safe ruby " light, and also the risk of chemical fog from prolonged immersion. These points have been elabor- ated with the intention of showing the advantage of working under proper conditions. It is hoped that they may explain many failures in cases where good results should have been obtained. Instructions for glazing Gelatino-Chloride Prints When the print has been prepared it is necessary to glaze and mount it on a cardboard. Too great stress cannot be put upon this part of the work. A properly glazed and mounted print is the final effort of the radiographer. Plate Glass should be thoroughly cleaned in w^arm water and soda to remove dirt and grease, and then well rinsed in plain water to remove soda. Polish ofi: carefully with spirits of wine, and soft leather. Sprinkle a httle powdered French chalk, and again poHsh off lightly with soft leather. Prints should be previously well hardened in alum or formalin. If alum is used, the solution should be filtered before use, and the print well washed after. If formalin is used, a short washing will suffice. Place the print direct from washing-water on to the glass, one corner first, allowing the surface to roll into contact ; the action of the water will then exclude air bells. Or the print may be placed on the glass entirely under water. Lay the glass on a firm flat table, cover with a piece of clean, smooth blotting-paper, and squeeze lightly with a rubber roller. Heavy pressure should not be used, but merely sufficient to remove the surplus water, leaving the print in actual contact with the glass. Backing. — Cut a piece of waterproof backing paper a little smaller than the print. Paste with stiff brush evenly and thinly, and squeeze lightly into contact with the back of the print on the glass. Leave till thoroughly dr^. Then insert the point of a knife under the edge of the print, when it will strip off with an enamelled surface. STEREOSCOPIC RADIOGRAPHY A great deal of importance is attached to stereoscopic radiography, many workers going so far as to state that a quick stereoscopic radiograph possesses as much value as a Rontgen cinematographic result. It is certainly most useful in depicting subjects like renal calculi, stomachs, intestines, and fractures, especially of the pelvis and femur ; but opinion is very divided as to its value in locating foreign bodies, many workers claiming that better results are obtained by the comparison of two different radiographs taken at a much wider angle. When observing any object or group each eye sees quite a different picture, but the two images thus seen are combined into one picture by the brain, which has the property of perspective. To accurately radiograph stereoscopically, therefore, it is necessary that the points of view should be the same distance apart as the pupils of the two eyes, but in radio- graphy it has been found that to produce the best rehef it is necessary to exaggerate the stereoscopic effect. It is necessary, therefore, to take two successive radiographs on two different plates, which are placed in exactly the same position, to keep the patient absolutely stationary, and to shift the tube a few centimetres to either side of the centre. The correct degree of movement for the tube has been calculated by Marie and Ribaut, who have given the following table, but this need not be absolutely followed if the movement of the tube is recorded. Marie and Ribaut's Table Thickness of part Distance of the Anti-cathode to the surface of the Body. | to be radio- graphed. 1 20 cm. 30 cm. 40 cm. 50 cm. cm. cm. cm. cm. cm. 2 4-4 9-6 16-2 ^ 4 2-4 5-4 8-8 13-5 6 1-7 3-6 6-1 9-3 8 1-4 2-8 4-1 7-3 Distance to which 10 1-2 2-4 4-0 6-0 j- the tube must be 15 1-8 2-9 4-3 displaced. 20 1-5 2-4 3-5 25 1-3 2-1 3-0 30 1-2 1-9 2-7 J The point to bear in mind is that the nearer the object of interest to the plate the greater the distance the tube must be moved between the first and second exposure. After the exposure and subsequent development the two 105 106 RADIOGRAPHY images must be optically fused into one, and for this purpose there are many forms of stereoscopes, such as the Wheatstone reflecting, prism stereo- scope, and the Pirie hand stereoscope. Both pictures can be reduced and viewed in a hand stereoscope. As to the necessary apparatus for taking stereoscopic radiographs, if only those parts of the body which can be kept stationary without effort are required, and time is not an important factor, then an ordinary stereoscopic plate-holder can be used where the patient lies upon a holder with a top which is transparent to the X-rays. Into this holder place two plate-holders, which can be exchanged without moving the patient. On the other hand, if stereoscopic results of those parts of the body which cannot be controlled voluntarily are required, then an automatic arrangement must be adopted to shift the tube and the plate synchronously and in- stantaneously (see Fig. 70). There are already several of these devices on the market, but they are daily being improved, and we shall no doubt shortly have a perfect one produced. Stereoscopic fluoroscopy has also been attempted, but although possible and indeed successful with parts of the body such as the hand and the foot, this has hardly been satisfactory with the thicker parts. THE LOCALISATION OF FOREIGN BODIES The demonstration of a foreign object in any part of the body is one of the most useful functions of the X-ray examination, and its accurate localisa- tion is one of the most difficult duties of the radiographer. Even after a body has been definitely localised, the surgeon may not be able to measure exactly the distances from given points so as to make his incisions and extract the foreign body at once. There are fallacies in the interpretation and mis- calculations of distance, and, lastly, it must not be forgotten that if a foreign body is located, the patient must be placed in exactly the same position at the time of operation as he occupied when the radiographs were taken. A slight degree of flexion or rotation of a limb will upset the calculations, and the foreign body may be found to be as much as 1 or 2 inches away from the spot at which it had been localised. It must also be pointed out that if a locahsation is to be of its greatest value it should be done immediately before the surgeon operates ; if possible it should be done in the operating theatre. Where many cases require investigation a small theatre should be attached to the X-ray department. Of the various methods for locahsing foreign bodies the most useful and probably the best known is that intro- duced by Mackenzie Davidson. The details of the method will be dealt with later. Modifications of this method exist, and have been used by many workers. Foreign bodies are met with in all parts of the body, and the localisation will vary in difficulty according to the part in which a foreign body is found. In the limbs they are comparatively easy of localisa- tion, but in the skull, thorax, and abdomen the greatest difficulty may be experienced. Probably the best all-round method of localisation in the latter regions is the stereoscopic. This is carried out in the same way as in ordinary stereoscopic work. Two plates are necessary, and in most cases it will be found useful to place on the skin of the patient an opaque body which will give a shadow, and may be used as a landmark for subsequent comparison. By employing cross wires the stereoscopic may be used in conjunction with Mackenzie Davidson's method. Stereoscopic plates should be developed together in order to secure, if possible, the same density of negative ; simi- larly the condition of the tube and length of exposure should be the same for each plate. A note should be made of the position of the plate in relation to the body of the patient. This will be found useful when it is necessary to 107 108 EADIOGEAPHY state the exact position of the foreign body in relation to fixed anatomical landmarks. Good stereoscopic negatives, when viewed in the stereoscope, show perfect pictures, with the correct perspective for the parts shown, though Fig. 89. — Wheatstone stereoscope. (Watson.) the exact localisation of a foreign body may be difficult or in some instances impossible. A Wheatstone stereoscope should be employed whenever possible, as it affords valuable aid by means of its adjustable parts in quickly getting the correct position of the plates. When this comparatively elaborate stereoscope is not available, a Pirie hand stereoscope will be found useful. Pirie Stereoscope for the Examination of X-Ray Negatives. — The Pirie stereoscope is arranged on entirely different lines from the instruments which have been heretofore employed for the examination of stereoscopic X-ray negatives. Instead of using reflecting mirrors, a double reflecting prism is used. For conveni- ence the prism is mounted in one of two metal tubes, which are bound together by a con- necting piece, the second tube being a plain one only, and serving to exclude extraneous objects from view. The stereoscope is light, the metal part being constructed of aluminium, and can be easily carried in the pocket. A feature of the Pirie stereoscope is the ease with which stereoscopic vision is obtained. It frequently happens that persons who are not accustomed to examimng stereoscopic negatives wish to do so, and with the old form of reflecting mirror stereoscope this has always been a difficult matter, very often ending in failure. With the Pirie stereoscope, however, it is almost impossible for anyone to avoid seeing the negatives stereoscopically. The negatives are taken in the usual manner and are placed side by side, either Fig. 90. — Pirie stereoscope. SIMPLE METHODS OF LOCALISATION ]09 in suitable boxes provided wtK electric light, or they can be rested on the framework of a convenient window. The distance at which the negatives are observed depends upon the distance between the centres of the negatives, that is to say, the size of the plates. For instance, the best position to inspect a pair of 12 inch by 10 inch negatives placed as closely together as possible is about 3 feet 6 inches. When looking at smaller negatives it is necessary to come much closer in order to obtain a comfortable stereoscopic effect, or with larger negatives the distance must be increased. The negatives should be on a level with the eyes and if possible slightly tilted towards each other. By concentrating the attention through the plain tube {i.e. the one with- out the prism) and centering the image on the corresponding side, a stereo- scopic effect is at once perceived even by those who are unaccustomed to stereoscopic work. The correct position of the foreign body may be located and a statement made as to its relative position to well-known landmarks, but when operation for removal is contemplated the surgeon should examine the plates on the stereoscope and form a mental picture of the position of the foreign body which should guide him throughout the operation. To facilitate this a stereoscope should be placed in close proximity to the operating theatre. Simple Methods of Localisation. — There are simpler methods for localisation which may be employed in cases which are not likely to require an exact degree of measurement. Foreign bodies in the limbs come under this heading. It is obvious that in some instances one negative is sufficient to indicate the position of the foreign body, though it is surprising how difficult an apparently easy case may become under some circumstances. All operations for removal should be undertaken as soon as possible after the radiograph. More difficult cases require more elaboration, and in all instances of bodies in the limbs two radiographs should be taken : (1) antero-posterior position, (2) lateral position. The limb need not be moved when these exposures are made. A simple plate-holder with a second one at right angles will suffice. The tube alone requires to be moved. An examination of the two negatives should give the position of the foreign body. In the plate taken in position (1), the distance from a given point, probably a bony landmark, is taken. The plate taken in position (2) shows the depth from the surface. In most instances this should be sufiicient, as the operator has only to measure the distances and make a mental note of the position. In order to get a graphic record of the measurements, a simple plate- holder can be constructed with an inch or centimetre rule, which slides over the surface of the plate so that it may be placed in relation to a bone or foreign body. A second inch or centimetre scale runs at right angles to the longi- tudinal one. The marks on the scale are rendered opaque by inserting pieces of wire into the wood at the correct distances. The second plate-holder is fixed at right angles to the first one and also has sliding scales. The 110 EADIOGEAPHY foreign body may be located by screening prior to the taking of the plates. When the two negatives are examined it is easy to locate accurately the G *o»fe Fig. 91. — Diagram to show method of taking a lateral view. A, Source of X-rays. H, Shadow of foreign body on plate. D, Foreign body. F, Shadow of bones. 0, Bones. G, Graduated scale. B, Limb. foreign body. The plates have on the surface an exact rule for measuring. For exact localisation the Mackenzie Davidson method should be employed. Method employed in Mackenzie Davidson Localisation. — The central ray emitted from an X-ray tube has to be definitely found. To do this it is necessary to have an arrangement for determining the central ray. The tube is accurately fixed on the box beneath the table ; the latter moves in two directions on trolley wheels. The central ray is located by means of cross wires, or a plumb-line rmming on pulleys and moving with the tube, so that whatever the position of the tube the plumb-line always indicates the position of the focus of rays upon the anti-cathode. The distance of the anode from the top of the couch is constant, and should be recorded on a convenient place on the couch ; the distance of the plate from the top of the couch must also be taken into consideration. The two added together give the distance of the anode from the plate. When working with the tube above the patient, the two positions of the anode are secured by moving the tube along a horizontal bar which is marked with a milhmetre scale, running both ways from a central point at zero. The sensitive plate or film is placed under- neath, and protected in the usual way by black paper, or it may be placed in a light-tight casette. Two wires are laid at right angles to each other on the photographic envelope, and so placed that one of them runs in the same direction as the horizontal bar which carries the tube above, and their point of intersection Hes beneath zero on the scale. The cross wires may be MACKENZIE DAVIDSON METHOD 111 fastened to a thin board or sheet of vulcanite, and retained in position over the sensitive plate by drawing-pins, or they may be permanently fixed to a frame, upon which the plate is placed. The marks corresponding to the cross wires should be painted with aniline ink or silver nitrate solution, so as to leave a mark on the body of the patient, and it is convenient to identify one of the corners of the plate by some opaque object, such as a small coin, with a corresponding sign on the adjacent skin surface. Two equidistant points are marked of? by clips, or any other method, at each side of zero on the horizontal scale bar, at a distance decided on by the operator. The focus- tube is drawn up to one side-clip, and an exposure made. It is then pushed A -0 over to the other clip, and a second exposure made of equal length. The dis- tance from the centre point of the anode to the plate is then accurately mea- sured. Accurate data have now been obtained, from which the operator may calculate the exact relation of a foreign body in the tissues to the aniline cross mark on the patient's skin. When the tube is operated from below a similar arrangement is used, the tube being first centred over a known point of the part to be radio- graphed. A scale is at- tached to a convenient part of the table and the move- ment to one side (a known distance) is made, say 3 cm. The tube-box is fixed and the exposure is then made. The plate is removed and a second one placed in exactly the same position. The tube is now moved 6 cm. in the opposite direction to the first movement, and the second exposure is made. It should be noted that the frame with the cross wires and the plates occupies the same position relative to the patient during the two exposures. It is also possible to make the two exposures on one plate by exposing only half at a time, thus enabhng a little time to be saved in the subsequent procedures for locahsation. Having obtained the radiographic records the next step is to proceed to the exact locahsation of the foreign body. This is done by means of the cross-thread localiser (Mackenzie Davidson). The apparatus consists of an adjustable horizontal bar, which is marked with a millimetre scale starting Fig. 92.- D C -Diagram showing Mackenzie Davidson method. (After Walsh.) .1, First position of tube. D, Shadow thrown on plate by B, Second position of tube. tube in A position. S, Skull or limb. C, shadow thrown on plate by F B, Foreign body. tube in B position. Dotted lines represent the paths of the rays. 112 KADIOGRAPHY from a central zero, and is notched to correspond on its upper edge ; a plate-glass stage marked with two lines at right angles to each other, the point of intersection lying exactly beneath zero on the horizontal bar. Beneath the stage is a hinged reflecting mirror. The developed negative or tracings of the two plates on a celluloid sheet is placed film upwards on the glass stage, and the shadow of the wires made to correspond with the cross mark on the stage. The bar is next raised or lowered so as to bring the zero of the scale to the same distance from the scale as that of the centre of the anode from the sensitive plate when the exposures were made. Two fine silk threads are next passed over the horizontal scale bar. Each thread has a weight at one end to keep it taut, and is fixed in a notch on the scale corresponding with the distance of the anode from zero during the original exposure. The other end is threaded into a fine needle fixed in a piece of lead. The path of the thread between the notch on the scale and the eye of the needle represents the path of the X-ray and is mov- able. A second thread is passed through the notch at the other end of the horizontal bar. It represents the path of the rays during the second exposure after the tube has been moved. With two such threads, then, it will be easy to trace the path of the rays in relation to a body interposed between the focus-tube and the sensitive plate. One threaded needle is placed upon any particular part of one of the photographic shadows of the foreign body, and the other needle upon a corresponding part in the second shadow. The point where the threads cross and touch each other will represent the position of the part of the foreign body chosen for location. A perpendicular is then dropped from the intersection of the threads to the negative below, and a mark made where the perpendicular touches the negative. The distance of the spot thus marked out from the cross wires is measured by a pair of com- passes. The operator is now in possession of the required measurements. If the distances are 3 cm. and 1 cm., and the depth from the crossing of Fig. 93. — Mackenzie Davidson cross-thread localiser. (Cox and Co.). MODIFICATIONS OF MACKENZIE DAVIDSON METHOD 113 the threads to the plate 2| cm,, then he knows that the foreign body lies at 2| cm. from the surface of the patient's skin, at a distance of 3 cm. and 1 cm. from the cross wires, in a quadrant that is easily determined by reference to the distinguishing mark placed there when taking the double-exposure radiograph. Dawson, Turner, and others have published a simple formula for localising. Two radiographs are taken on one plate by moving the tube a known distance. The distances are measured from tube to plate (A), between the two posi- tions of the tube (B), and between the two shadows on the photo- graphic plate (C). Let x equal the Fig. 94.- -Diagrani to illustrate simple formula for localising. (After Walsh. ) distance of the foreign body from the plate. Then X axe h+c Supposing a to be 33 cm., 6 10 cm., and c 1 cm., then 33x1 x = = 3 cm. 10 + 1 Mackenzie Davidson has suggested a short method of locaUsation which, while based on his original method, allows of more rapid locaUsation. The central ray is determined and the position fixed by means of a plumb line. The foreign body is located directly under the point of the plumb hne. A mark is made upon the skin, a plate is exposed, the tube is moved a known distance, and a second exposure made. The depth of the body is deter- mined by calculation in the ordinary way. Two cross wires, arranged at right angles, must be used. Dr. Hampson has simplified this method still further by having a graduated scale fixed to the fluorescent screen. By movement at the time of screening he is able to say the depth of the foreign body at a point vertically below the skin mark. This method can only be used at a fixed distance in all cases unless separate scales are worked out for each position of the tube in relation to the screen or plate. The method is more fully described on p. 114. 8 Fig. 95.'— To illustrate Mac- kenzie Davidson's short method of localisation. 4 : X : : 10 : 50 - a-. F B, Foreign body. A, First position of tube. B, Second position of tube. C, Position of image of F B in first position. A mark is made on the skin at this spot. D, Shadow of T^iJ in second position of tube. 114 RADIOGEAPHY l^ i trT ' i" f Ti'V; i ^T ' VTi'k"r''r"'Y"'1 r " ' ^ '' cm. Depth: RB. Fig. 96. — Graduated scale in Hampfsoii localiser. Hampson's Method of Localisation.— The method introduced by Dr. Hampson is briefly as follows : Place the patient on the couch and arrange the tube in the tube-box with the focus point at a determinate distance, say 50 cm., beneath the surface n of the screen. Contract the fm on \crppn ' '■ *^" ^^i^^it- diaphragm openmg so as to make it easy to centre the foreign body in the field of view. The rays through it will be practically vertical, and a small arrow head or other metallic mark fixed on the skin will locahse the selected point of the foreign body in two dimensions, along and across the trunk or limb. For the estimation of the depth a mark is placed on the glass of the screen over a selected point of the foreign body. Move the tube-box, and with it the focus, a known distance, say 10 cm., and mark on the glass the new situation of the selected point, opening the diaphragm wider if necessary. Measure the distance that the shadow of the point has travelled, read this off on the upper side of the scale. Fig. 96, and the corresponding number on the lower scale will be the depth of the foreign body beneath the screen. If the part of the patient under examination is concave and does not touch the screen, this must be allowed for in stating the depth. In cases where the distance between the screen and focus point cannot be permanently adjusted, the same result can be obtained with very little trouble and delay. Ascertain by measurement what the distance is, mark the traverse of the shadow as before, and then work out the result as follows : AB, Fig. 96a, is a line equal to the vertical height from screen to focus. AC is the horizontal movement of the focus. BD is the horizontal movement of the shadow on the screen. Draw a line DC intersecting AB in E. Then BE is the depth of the foreign body below the screen. The correctness of the result depends on the accuracy of the measurements, so these should be made as few as possible in order to reduce the occasions for inaccuracy. It is, therefore, better to measure directly the distance from focus level to screen by means of a large pair of callipers. Other distances than 50 cm. may be used, but a separate scale must Fig. 96a.- — Hampson local- iser. Diagram to illus- trate method. FOREIGN BODIES IN SPECIAL LOCALITIES 115 be prepared for each distance. A table prepared for the 50 cm. interval will be found useful : -h cm. ti'averse on screen means a depth of 2J cm. i „ „ „ H :, 2 „ „ „ 8^ „ 3 „ „ „ Hi „ 4 „ „ „ 14^ „ Shenton's Method of Localisation. — Shenton relies entirely on the screen method of examination and denounces all radiographic methods. He uses a circular diaphragm of small diameter and centres this accurately under the foreign body. A metallic pointer or probe is now passed between the screen and the limb under investigation, and its tip placed over the shadow of the foreign body, or to be more correct, the shadow of the probe is watched until it coincides with the shadow of the bullet, the probe is held steadily in position, the room is lighted up, and the exact position of the probe point is marked upon the skin surface. This is a point immediately over the bullet, and it is manifest that an incision carried to a correct depth must find the object sought for. It remains therefore to ascertain the exact depth at which this lies. A straight probe is used. Around it is twisted a piece of lead foil or soft wire so as to make an appreciable bulge. Turn the limb upon its side, i.e. at right angles to its former position ; then place the tip of the prepared probe on the spot marked upon the skin, letting the probe lie horizontal to it, or in other words, parallel with the screen. Next slide the piece of lead foil along the probe until its distance is equal to that of the point from the bullet or other foreign body. The distance between the point of the probe in contact with the skin and the bulge caused by the lead foil is equal to the distance between the skin surface and the position of the bullet. The distance may be measured upon the probe, and the operator is in a position to say that the bullet lies under the spot already marked upon the skin, and that the depth corresponds to a known distance as measured by the probe and the movable bulge upon it. Shenton has introduced a localiser which he says is really a depth-gauge. This is a very ingenious and useful apparatus for locahsing foreign bodies in the limbs. Localisation of Foreign Bodies in Special Localities Localisation of Foreign Bodies in the Eye and Orbit. — (a) Mackenzie Davidson method. This is a method for exact localisation of a foreign body in the eyeball, A special adjustable head-piece, fixed to a chair, is employed. It usually consists of a horizontal arm, carrying an open rectangular framework, across which two wires, one vertical and the other horizontal, are stretched, and against which the photographic plate is placed. Attached to the framework is a small rifle " sight," at the same level as the intersection of the cross wires, the use of which will be presently 116 KADIOGRAPHY described, while below and to one side is a chin-rest, so that the patient does not move his head while the plates are changed and the exposures made. Parallel to the arm carrying the open framework is another arm, bearing a sliding clamp for the X-ray tube. In this way the tube always moves parallel to the horizontal cross wire. The tube is first arranged with the glistening point of origin of the X-rays on the anode exactly opposite the intersection of the cross wire, this being done by arranging the rifle " sight," the point of intersection of the wires, and the point on the anode, all in the same straight line. The distance between the point on the anode and the intersection of the wires, usually about 35 cm., is carefully measured. The patient now sits in the chair, with his head between the two horizontal arms, and with his chin placed on the chin-rest, places the side of his head (injured eye side) against the cross wires, so that they are between his head and the photographic plate, and looks straight forward, as if at a distant object, so that the visual axis of his eye is parallel to the horizontal cross wire. A piece of lead wire, exactly 1 cm. long, is fixed to the lower eyelid of his injured eye by adhesive plaster, and the distance between the upper end of the wire and the centre of the cornea in this position noted. The tube is now moved 3 cm. to one side of its original position and an exposure made. Another plate is put in position, and the tube slid 6 cm. in the opposite direction, and another exposure made without the patient moving his head. The two plates are developed and fixed in the usual manner. The head-piece is usually made with the cross wire framework and tube-holder fitting on both arms, so that either eye can be radiographed. The shadows of the foreign body, if there is one, on the negatives have now to be localised, and for this purpose the cross-thread localiser is used. This is simply an apparatus for placing the negatives in exactly the same geometric conditions under which they have been made, and it has been fully described on page 112. With these means we can now reconstruct the exact conditions under which the two skiagrams were taken. The horizontal bar is arranged so as to be at the same distance from the plate-glass as the point on the anode was from the cross wires. The two threads passing through the two notches 3 cm. to each side of the central point of the bar will, therefore, represent the paths of the X-rays when the exposures were made. A thin piece of varnished celluloid, also having cross lines scratched on it, is placed against the film side of the negative, so that the cross lines corre- spond in both, and the position of the foreign body is marked by pen or pencil on the varnished celluloid, as well as the shadow of the lead wire on the lower eyelid. The same is done with the other negative using the same piece of celluloid. In this way we get two shadows of the foreign body and of the lead wire in their relation to one outline of the cross wires. The celluloid with these markings is now placed on the plate-glass, with the cross lines corre- sponding in both. The ends of the cross threads attached to the weighted needles are placed on the markings of the foreign body in such a way that the shadow of the foreign body to the right is at the end of the thread passing FOREIGN BODIES IN THE EYE AND ORBIT 117 through the notch on the left, and vice versa. These threads representing the paths of the X-rays in the two exposures, the points where they cross will represent the point in space of the foreign body. To localise the point one has to measure the perpendicular distance of the intersection of the threads from three planes at right angles to each other. The vertical distance of the point of intersection from the celluloid is measured by a pair of compasses, and this distance represents the depth of the foreign body from the skin, as the side of the head was against the cross wires. Next, the distances between the two vertical planes represented by each of the cross lines, and the point of intersection, are measured. To do this an upright square is placed with its edge coincident with one of the cross lines, and the perpendicular distance is measured by compasses. The same is also done with respect to the plane of the other cross line. These measurements determine a point on the skin at the side of the head directly beneath which the foreign body lies, provided we know the relation of the cross wires to the patient's skin. If the foreign body is of any size it is necessary to determine the exact location of each end of its shadow, but if it is very small one measure- ment is sufficient. As the location of a foreign body as being at such and such a depth from the skin of the temple would not give the surgeon much practical help, one must be able to state its relation to the part of the eyeball. It was for this reason that the lead wire was placed on the lower eyelid. The location of the upper end of the lead wire is determined in relation to the three planes exactly as the foreign body was, and after this it is merely a matter of addi- tion or subtraction to be able to tell how many centimetres the foreign body lies behind, at a higher or a lower level than, and to which side of, the upper end of the wire. We already know the distance between the upper end of the lead wire and the centre of the screen, and as the wire is usually at the same level as a vertical line from the front of the screen, we can give the surgeon a definite point at which the foreign body is lying in relation to the centre of the cornea, so many centimetres behind parallel to the visual axis, so many horizontally to the nasal or temporal side, and so many above or below it. For example, suppose we have found the position of the inter- section of the cross threads marking the foreign body (6) to be 1-9 cm. above the celluloid, 3 cm. behind the plane of the vertical cross line (B), and 1 cm. below the plane of the horizontal cross line (A), and the intersection of the thread working the upper end of the lead wire {a) to be 2-9 cm. above the celluloid, 1-2 cm. behind the plane of the vertical line (B), and -6 cm. below the plane of the horizontal line (A), then by subtraction the foreign body is 1 cm. to the temporal side, 1-8 cm. behind and -4 cm. below the upper end of the lead wire, and as the latter is -5 cm. below the centre of the cornea, we are able to say that the foreign body lies 1-8 cm. behind, 1 cm. to the temporal side, and -9 cm. below the centre of the cornea, with the eye looking at a distant object. Lastly, it should be remembered that the skiagrams taken in this way are stereoscopic, and if so viewed will give a stereoscopic effect ; and as 118 KADIOGRAPHY the lead wire is of the known length of 1 cm., it maybe used stereoscopically as to scale to estimate approximately the size and position of the foreign body. (6) Sweet's Method of Localisation. — Dr. Sweet's method of localising foreign bodies in the eye and orbit is carried out by means of the special apparatus designed by him for the purpose. The illustration on page 124 shows the device, which comprises a head-rest for securing the head of the patient above a plate-holder, so that plates can be changed and one-half exposed without disturbing the patient. The pneumatic cushion shown is placed between the patient's head and the plate-holder. In use, the patient's head is placed in position and the indicator shown on the right-hand side is placed in exact alignment with the centre of the cornea. The indicator is then pushed gently up to the eye itself, and when just touch- ing it is released and carried back by a spring exactly 10 millimetres. Two exposures are made, the first with the anti-cathode of the X-ray tube in the same plane as the plate, and with one-half of the plate covered. The un- exposed half of the plate is then brought into position, and a second exposure made with the tube slightly tilted. After development the positions of the foreign body and of the indicator are plotted upon a special chart sheet, a number of which are supplied with every instrument. It should be noted that it is not necessary to place the tube at any known distance from the plate, or move the tube an exact distance for the second exposure. The special charts prepared on squared paper show exactly the relative position of the indicator and foreign body. (c) Stereoscopic Method. — This is a most useful method, and should always be employed, even when an exact localisation by other methods has been carried out. It is necessary to take the radiographs in two positions : (1) Lateral, and (2) antero-posterior. When these radiographs are examined httle doubt should exist as to the size and position of the foreign body, provided the operator knows the position of the plates when the radiographs correspond. When used in combination with Mackenzie Davidson's method it is the most accurate of all. (d) Simpler methods may be employed. Two positions are necessary : (1) Lateral, (2) antero-posterior. Two pictures of the foreign body are obtained on one plate by maldng the first exposure with the eye looking upwards, the second with the eye looking downwards. Movement indicates the position of the body in relation to the eyeball. An antero-posterior plate should also help to locate the position of the foreign body. This method is necessarily inaccurate, and can only be used to determine the presence of a foreign body. Should operation be necessary, then an exact localisation by the Mackenzie Davidson method must be carried out. In regions of the body, such as the thorax and abdomen, the same measures may be employed. Stereoscopic radiograms of the thorax in the antero-posterior and lateral posi- tions should sufiice to indicate the position of the foreign body. The cross- thread method of localisation should be employed as a confirmatory measure. Localisation of Foreig-n Bodies in the Skull. — The methods SIMPLE METHODS OF LOCALISATION 119 available are (a) stereoscopic ; (6) stereoscopic combined with Mackenzie Davidson method. A simple method may be employed when it is not possible to have access to the two methods referred to. It is one which anyone possessing an X-ray installation can carry out, and which has proved useful in many instances. Three plates are required : (1) Right lateral, (2) left lateral, (3) antero-posterior. For the localising of foreign bodies in the head the skull is divided into sections by means of flexible wire. A piece of wire is fixed in the longitudinal diameter, extending from the nasion in front to the external occipital protuberance behind. A second wire is carried from the nasion through the centre of the external auditory meatus backwards to end Fig. 97. — Bullet in brain. Fragments in face. below the occipital protuberance. A third wire is carried vertically over the skull from one external auditory meatus to the other. Three plates are taken and compared. When the foreign body is sharper on one plate than on the others it indicates that it is nearer to the side on which it is sharpest. The antero-posterior plate confirms this observation. The lateral pictures also serve to show the relationship of the foreign body to a well- known landmark at the base of the skull. Localisation of Foreig-n Bodies in Regrion of Hip and Shoulder. — In these regions it is impossible to get more than one position, so stereo- scopic radiographs should be taken. These combined with the Mackenzie Davidson method give the most accurate results. Localisation of Foreig-n Bodies in the Limbs. — In a number of instances it may be possible to locate the foreign body by screening alone. 120 EADIOGRAPHY In other instances one of the methods described by Mackenzie Davidson, Hampson, Shenton, and others may be used. The position of the foreign body is ascertained and a mark placed on the skin surface immediately Fig. 98. — Fracture of lower jaw ; foreign body in soft parts ; a portion of shrapnel above the jaw bone. over it. The tube is then moved and the second position of the foreign body noted. It is then a matter of calculation to estimate the depth of the foreign body. Hampson does so by means of the graduated scale, Shenton by the use of the probe with a bulging point on it, and by placing the limb at right angles to the position it occu- pied when the mark was placed over the foreign body. Localisation of Foreign Bodies in Deep Parts of the Body. — In several of these regions the locahsation of a foreign body is a matter of extreme difficulty, notably in the thorax abdomen, pelvis, axilla and region of the hip. The exact position may be marked out both stereoscopi- cally and by the Mackenzie Davidson method, and yet the necessity of avoiding anatomical structures may render the subsequent removal difficult. In some cases it may be helpful to take a lateral view of the thorax or Fig. 99. — Fragment of shell in region of hip-joint. FOREIGN BODIES IN THE LIMBS 121 spine. This may enable us to say at once where the foieij^n body lies Fig. 100. — Fracture of tibia, portions of shell in limb. Fig. 101. — Fragments of bullet in limb ; arrows indicate position of wounds. Graduated scale over bone. Hori- zontal line indicates distance from edge of bone, oblique line distance from upper arrow. in relation to a bony landmark, but for exact localisation it is necessary to use the cross thread method. It has been suggested that X-ray localisation in several cases bas complicated the removal rather than been helpful. In order to obviate such complications the following method might be adopted. The foreign body should be accurately located by the Davidson method and stereoscopic plates taken. The exact spot is marked out and the plates viewed in the stereoscope. These two give the exact spot where the body hes. For removal the following pro- cedure is suggested. In the operating theatre or the X-ray room a simple table is con- verted into a combined X-ray and operating-table by using one of the simpler tube-stands which allows of a tube- carrier being placed under the table, a second arm carrying the fluorescent screen. The latter has Fig. 102. — Fragments of shrapnel in hand. 122 KADIOGRAPHY attached to it a small scale with moving points, such as the Hampson, or one made by Watson and Sons. The tube is accurately centred and the distance between the anti-cathode and the screen ascertained. The patient is prepared for operation and placed on the table. The body is then located on the screen, the skin being marked by a small incision at a point corresponding to the shadow. The foreign body lies just mider this spot. The depth is ascertained by a displace- ment of the tube a ^li known distance, the scale on the screen automatically record- ing the depth in cen- timetres. This read- ing should be com- pared with the result obtained by the Mac- kenzie Davidson method, and if they correspond the sur- geon has an accurate statement of the depth of the foreign body. If owing to the anatomical struc- tures interposed on the hne of the body it is not possible to cut straight down into it, it can iii nearly every case be found by probing. Should the surgeon fail to find the body quickly, aimless probing should not be continued. The hght of the room should be excluded, the X-ray tube turned on, and the surgeon will at once be able to see how far his instrument is from the foreign body and guide his forceps to it. The length of time the operator is exposed to the rays need not be more than a few seconds, but if many cases daily require to be screened, some method of protection must be employed. By cutting down the diaphragm so that only a small pencil of rays emerge and using long-handled instruments there should be very httle risk to the operator. Fig. 103.— Arrangement of X-ray tube and fluorescent screen for accurate localisation by screen or plate. RADIOGRAPHY OF THE NORMAL BONES AND JOINTS A thorough acquaintance with the normal appearance of these parts is necessary on the part of the radiographer before he proceeds to an interpreta- tion of the many variations which he may be called upon to describe. Not only must he know the chief bones and joints from any one aspect, but he should by a careful study of the parts know them from any point of view. It may not be always possible to get the patient into the position of ease which is generally the one in which the parts can be radiographed most readily. A patient sufiering from an injury to a joint may not always be able to take up a position on the X-ray table which will enable the operator to radio- graph the part to the best advantage ; the apparatus may have to be adapted to the patient instead of the patient to the apparatus, hence it is necessary that the operator should be familiar with the parts from several points of view. In ordinary cases of fracture of the bones in the vicinity of a joint it is always a good rule to radiograph the parts in at least two positions. The Skull and Accessory Sinuses There are several positions of the skull which lend themselves to the production of good radiographs. Of these the lateral is the most useful, as it gives a general impression of the whole skuU and soft parts, the articulations at the base, and a lateral view of the cervical vertebrae. There are various modifications of this position, to be considered in detail later, which are extremely useful when special areas require to be investigated. To get good radiographs of the skull, it is essential that the head should lie fiat on one side, and be held absolutely still during the exposure. A useful instrument for fixing the skull is that supplied with the Sweet localiser, since it may be used in all positions of the skull. It has two or more clamps attached to a base, upon which the plate may be placed. These clamps keep the head in the same position while several radiographs are produced. Among the numerous pieces of apparatus which can be used for the radiography of the skull, there may be noted a simple chair, devised by Dr. Martin Berry, which promises to answer all the requirements of the radiographer. This apparatus has a movable back, with a circular hole in it. The movement is in the vertical direction, to adapt the central hole to the varying length of the patient when seated in the chair. Side clamps fix the head after the necessary angle has been determined. This angle is obtained by a rod moving along the quadrant of a circle. The head 123 124 EADIOGEAPHY is placed to correspond with the angle on the apparatus, the plate being placed always at the same angle in relation to the tube. An efficiently protected tube-box is placed on the back of the chair. It can be accurately centred, and has both vertical and transverse movements to facihtate rapid adjustment behind the part to be radiographed. The tube always occupies the same re- lationship to the plate, the head being tilted to the required angle. To obtain a picture of the two sphenoidal sinuses side by side, a plate is placed under the chin and the tube over the vortex at right angles to the plate. A film placed in the mouth well backwards under the head and soft palate will give a similar picture. Or the patient may he on a couch with the plate under- neath and a compressor extension tube brought down on to the head ; this serves the double purpose of fixing the head and cutting ofi secondary radia- tions from the tube. The priaciple of the compressor tube has been already dis- FiG. 104. — Sweet localiser. cussed. Care must be taken to see that the long axis of the tube is parallel with the plate, and that the anti-cathode of the tube is accurately centred in the tube-box before the tube is brought into position. For general purposes a central position of the tube is all that is necessary, the anti-cathode being over the centre of the plate, and the base line of the skull corresponding as nearly as possible with the centre line of the plate in its longest diameter. The base line of the skull can readily be determined by a method elabor- ated by Dr. E. W. A. Salmond and the author. A point is taken on the front of the face corresponding to the nasion, and a line is drawn from this point backwards through the external auditory meatus to the occipital bone, ending in the vicinity of the external occipital protuberance. From this line as a base, other lines may be drawn perpendicularly upwards at stated PLATE I. — Normal Skulls. a, Lateral view of normal skull, showing frontal sinuses, sphenoidal sinuses, sella turcica, temporal bones, cervical vertebras, and lower jaw. h, Antero-posterior view of adult skull, showing frontal sinuses, orbits, nasal fossae, antra, etc. Frontal .sinus on left side is opaque. c, Lateral view of skull to show the sella turcica, articulation of spine to skull ; the temporo- maxillary articulation on one side is well seen. KADIOGRAPHY OF THE SKULL 125 intervals, and the skull divided iato three or more sections, these perpendicu- lar lines being utilised as central points for the radiography of particular areas of the skull and face. The most useful lines are those drawn at the half and third distances, or the whole line may be divided into thirds or quarters. It is hardly necessary in a work of thLs kind to describe variations of this base line, but for practical purposes several useful methods of localisation of areas of the skull will be described. For the examination of the mastoid Fig. 105. — Dr. M. Berry's chair for frontal sinuses, etc. region a good technique has been described by Dr. Howard Pirie. The following is the technique he recommends : Technique. — The patient should he prone on a firm couch. The head is supported on an inclined plane^ making an angle of 25 degrees with the plane of the couch, as shown in Fig. 106. The photographic plate rests on this inchned plane. The head is rotated 90 degrees so that the patient looks directly to his side ; this brings the mastoid into contact with the plate. The pinna of the ear is turned forward, so as to obscure the mastoid as little as possible. The source of X-rays is placed vertically above the head, and the perpendicular ray is made to fall on a point 2 inches above the highest point of the pinna. The mastoid on each side must be skiagraphed separately. The glass of the focus tube should be 9 inches away from the hair. The exposure required will turn a Sabouraud pastille placed at 2 centimetres from the glass to one-third of the B tint. A medium hard focus tube (4-5 Benoist), 126 EADIOGRAPHY with 30 milliamperes for fifteen seconds from a Snook apparatus^ gives a plate wMch should be fully developed in seven minutes (Ilford plate and developer). Skiagraphs of both right and left mastoids must be made of every case, as a single skiagraph of one mastoid is of little value. A different focus tube should be used for each mastoid, as it is rarely possible to get one tube to remain constant in vacuum for both exposm-es. Both focus tubes must, of course, be of the same hardness. This is one of the most important points in the technique ■ — viz., to have two similar tubes of equal hardness and quality. The American- made tubes lend themselves to this better than any others I have used. Having secured radiographs of both right and left mastoids, one should place them side by side in a viewing-box, and note any differences. The radio- graph should show : 1. The articulation of the lower jaw, and the posterior border of the ascend- ing ramus of the jaw. 2. The auditory canal, placed behind the articulation of the lower jaw, and separated from it by about one-quarter of an inch. 3. The air cells, which form a reticulum extending from the articula- tion of the jaw backwards. The cells usually appear larger in the lower part, and smaller above. Sometimes they extend forwards above the articulation of the jaw into the base of the zygoma. It should be remem- bered that the cells extend well behind the limit of the mastoid process. 4. The petrous bone surrounding the auditory canal, appearing as a dense area superimposed on the mastoid cells. 5. The outline of the lateral sinus should be faintly indicated running through the posterior half of the cells. 6. The foramen magnum, appear- ing as an elliptical opening with part of the first vertebra crossing it. 7. The outline of the pinna of the ear. Acute mastoiditis shows the following departures from the above description : 1. The air cells are obscured, but can still be faintly seen. 2. The outline of the lateral sinus may be a little more defined than normally. 3. The petrous bone is denser. 4. The whole mastoid region is denser. When one gets an absolutely normal mastoid on one side, and the other side presents the appearance just described, together with certain clinical signs and symptoms, one is justified in diagnosing acute mastoiditis. Chronic mastoiditis is very typical in a skiagraph. It presents the following departures from the normal : 1. The air cells are completely absent. 2. The petrous bone stands out as a very dense, roughly triangular area, with its apex pointing upwards and backwards. 3. The posterior border of the petrous bone forms part of a sharp crescent- FiG. 106.- -Positioii for nidiograpliy of the mastoid sinuses. (Pirie. ) PLATE II. — Normal Skulls. a. Skull of child, plate on anterior aspect showing nasal fossae ; teeth well shown ; there are several iinerupted teeth seen. 6, Mid area of skull ; a line has been placed on points giving the radiographic base-line ; the line runs through the base of the sella turcica (dry skull). c, Lateral view of skull in living subject ; probes have been placed in the frontal and sphenoidal sinuses. RADIOCJKAPHY OF THE FRONTAL SINUSES 127 shaped line. Tliis crescent-shaped line corresponds with the upper and anterior border of the lateral sinus. 4. Tlie lateral sinus is fi-efjuently very well shown. (1) Radiography of the Sella Turcica.- A useful method for the radiography of the sella turcica has been described by Dr. Finzi. The patient is placed upon the couch and the tube centred from below. To deter- mine the exact position two small coins are placed one in each ear. After these are superimposed under the screen, the tube is then moved upwards and forwards 1 inch in each direction, and the radiograph taken. A perfect picture of the area required should be obtained. When radiographing particular areas of the skull, the diaphragm should be shut down to the smallest possible size, or if the tube ls used overhead a small extension tube should be inserted between the tube and the patient. Pictures obtained in this way will be found to give much finer detail than those taken with a wide diaphragm. It is important to note that in radiographs of the skull as much detail as can be obtained is desirable. (2) The Examination of the Frontal Air Sinuses. — Two methods may be employed : (a) a lateral view of the skull, showing the air sinuses in profile ; (6) antero-posterior, the plate on the front of the skull and the tube behind. A direct antero- posterior view does not show the sinuses at all well, the overlapping of the shadow caused by the occipital and temporal bones obscuring the detail in the frontal and acces- sory sinuses. There are two routes by which the rays may be passed through the back of the skull. (1) The tube may be centred below the bony mass formed by the occipital protuberance : we still have to traverse the thick parts of the base of the skull. (2) A better method is to place the patient face downwards on the photo- graphic plate, the latter being placed at an angle of 25 degrees. The tube is centred well in front Combined chair with clamps for flxation of the head and an adaptable plate-holder. of the occipital protuber- ance, and an oblique though somewhat distorted view is obtained which Fig. 107. — Chair for cranial radiography. 128 EADIOGKAPHY shows the frontal air sinuses well. Plate I., showing frontal air sinuses, taken by this method, illustrates the points to be examined. (3) For the Examination of the Sphenoidal Sinuses, the Ethmoidal Sinuses, and the Turbinate Bones, a plate is fixed on the front of the face, and the tube centred just a little below the occipital protuberance. This position should also show the bones of the face and the maxillary antrum. The teeth are also well demonstrated. The condyles of the jaw and the an- terior view of the tempero-maxillary articulation are also seen, while behind and a little external is the mastoid process, with its air cells clearly shown. Plate I., representing a normal skull taken in the lateral position, shows Fig. 108. — Chair for cranial radiography. all the important structures at the base of the skull ; the three levels are well shown, and the various air sinuses are distinctly seen, notably the frontal air sinuses. Taking the bones of the skull from before backwards, one sees the orbital plate of the frontal bone, the anterior clinoid process, the sella turcica, the posterior clinoid process standing well in relief ; extending backwards, the petrous portion of the temporal bone appears as a denser irregular shadow ; and, immediately behind, the mastoid air cells are promi- nently shown. Then, at the posterior portion, the well-marked depression formed by the occipital bone is shown. The thickness of the bony wall of the section of the skull shows the two layers of bone with the cancellous bone between them. PLATE III. — Skulls showing Departures from the Normal. a, Lateral view of skull, showing erosion of occipital bone the result of injury with secondary ■disease of bone. Note large frontal sinuses. b, Skull in a child, showing moulding of the cranial bones resulting from intracranial pressure. c, Skull from a case of tumour of the brain, situated at the sella turcica ; the detail in the region is lost. PLATE IV. — Lower Jaw and Cervical Region. a, Dentigerous cyst iu lower jaw (buried tooth). 6, Fracture through ramus of lower jaw. Skull showing good detail in soft parts, absence of teeth, calcified cervical glands. d, Bismuth food in stricture at upper end of oesophagus. THE LOWER JAW . 129 In the region of the neck the cervical vertebrae are shown lq profile, the styloid process extending downwards and forwards between the cervical vertebrae and the descending ramus of the lower jaw. The zygomatic arch is seen extending forwards on the lateral aspect of the face. The superior maxilla gives an irregular shadow and the anterior shows a clear space, the nasal bones are faintly outlined in profile, and the lower jaw is also shown in its lateral aspect. (4) The Lower Jaw is an important bone, and rather difficult to demon- strate satisfactorily. It may be shown by two methods : (a) showing the whole of the bone in a skiagram of the face ; (6) portions of the bone may be demonstrated by placing a film inside the mouth agaiast the part of the bone it is necessary to show, and using the focus tube outside. The picture then obtained is a small one, but quite large enough to show a fracture, an abscess, or disease or damage to a tooth and its socket. The tempero-maxUlary articu- lation of either side can be satisfactorily shown by centering the tube behind and a little below the angle of the jaw on the more distant aspect from the plate, Plate I., Fig. h shows the chief bony points of the skuU and face taken from the antero-posterior position. The plate was placed on the face, with the focus tube behind. The orbits are well marked, and the nasal cavities show a considerable amount of detail, which is of great value when one has to consider the possibility of fracture in these regions. The antrum of Highmore is clearly defined, the zygomatic arch stands out prominently, the lower jaw is thrown out in relief, and behind there is a distinct picture of the mastoid portion of the temporal bone with the air cells. Plate I., Fig. c shows a small and more distinct view of the central portion of the bony parts of the skull. The points to observe are the levels of the bone of the skull in relation to the exterior, the clinoid processes with the sella turcica between, the relation of the chief sutures to the various levels, and the well-marked grooves in the inner table of the skull for blood-vessels. A clearly defined shadow is thrown by the pituitary body situated in the sella turcica. The cervical vertebrae in relation to the bone of the skull show up well. The condyle of the lower jaw, situated in its articular cavity, is also evident, and a fairly good idea of the general contour of the latter. (5) The Examination of the Mouth, and especially the Teeth, is one which calls for special attention. The general outline can be obtained by plates placed on the exterior, the tube being angled to prevent overlapping of the shadows produced by the two sides. Better results can be obtained when films are placed in the interior of the mouth against the area required, the tube being centred over the film from the outside. A suitable mouth gag may be used ; this possesses the great advantage of preventing movements during the exposure ; a piece of cork or a towel rolled up tight is also very efficacious when other appliances are not at hand. Special appliances have been devised for the retention of the film in the mouth. A suitably-shaped cork is provided with a slot, into which various rectangular plates of metal are slipped. These metal plates are soft, and can 9 130 EADIOGEAPHY be bent into any curve to suit the contour of the mouth, and thus secure a close contact. The films are wrapped up in paper as usual, with a small loop of paper left at the back, which is slipped over the metal plate, so that any curve to which the plate is bent also carries the film with it. The cork is gripped in the mouth by the patient, it being obvious that this method enables the film to be held in any position inside the mouth without any further device or support. The Cervical Region The best positions in which to radiograph this area are : (1) The antero- FiG. 109. — Upper cervical region, antero-posterior view. Taken with plate behind and an extension tube in front of the open mouth. posterior, and (2) the lateral. The antero-posterior is comparatively easy in the lower two-thirds. AVhen the patient is placed with the posterior aspect on the plate and the tube centred over the middle of the plate, a view is ob- tained of the whole of the cervical vertebrae and the upper dorsal, the apices of the lungs coming into the picture, as do also the sternal ends of the clavicles and the manubrium sterni. The upper cervical vertebrae are obscured by the basi occiput and the lower maxilla. Should it be necessary to obtain an impression of the first three cervical vertebrsB, other methods must be adopted. The base of the occiput and the THE CERVICAL REGION 131 first and second cervical vertebrae may be examined by placing a plate on the posterior aspect ; and by using a small extension tube, with the mouth opened to its widest extent, a good radiograph may be obtained which should show the condyles of the occipital bone, the odontoid process of the axis, the atlas, and the third cervical vertebra. The lateral view of the cervical area shows the whole region from the occiput down to the upper dorsal vertebrae. This is a good method for ascertaining the condition of the bodies of the cervical vertebrae, the integrity of the spinal canal, and the presence of abnormalities of the region. The presence of cervical ribs can best be shown by the antero-posterior position. The cervical region has been partially shown in Fig. 109, but it is necessary to illustrate this particular region fully, for it is here that the difficulty of show- ing a fracture or dislocation may be very great, and in some in- stances impossible. An antero-posterior view of the neck region is not a very satisfactory one, because of the superimposing of the occipital region and the lower jaw. In cases where it is desirable to show the atlas and axis, and the articu- lation between the former and the occipital bone, it is necessary to take the skiagram through the open mouth, as described in detail above. The resulting picture is necessarily small, but large enough to include the parts desired. The position usually taken is the lateral one, with the head rotated towards the plate. It is then possible to get a fairly good outline of the seven cervical vertebrae and the adjacent portions of the base of the skull. The bodies of the cervical vertebrae are readily shown, but to get accurate outlines the head must not be moved to either side. Fig. 110. — Normal cervical and upper dorsal region showing the sterno-clavicular articulation. This position is useful when examinations for cervical ribs have to be made. The Bones of the Chest The Clavicles may be examined in their entire length, or in sections when the shoulder or upper thorax are in the picture. The patient is placed with the plate on the front of the chest, and the tube is operated either from below or from above, whichever is the more convenient. The Sternum has often to be examined, the position in which it is usually taken being from behind forwards. The picture is usually confused by the shadows of the mediastinum and spinal column. An oblique lateral view 132 EADIOGEAPHY of tlie thorax enables us to examine the whole of the sternum with its articula- tions. The picture is naturally somewhat distorted, but nevertheless a good idea may be obtained of its condition, injuries and tumours being readily shown. The ribs can be shown in these positions, the lateral position showing the ribs in their entirety. The Dorsal Spine Two methods are used here : (1) an antero-posterior, with the plate on the posterior aspect of the spine ; (2) a direct lateral view. The latter may be obtained by placing the plate on one side and the tube on the other, the arms being extended above the head, to get rid, so far as is possible, of the shadows of the scapulae. The bodies of the vertebrae are then well seen, as is also the posterior portion of the column with the transverse process, the laminae, and spines of the vertebrae. The spinal canal can also be seen in the plate. In taking the antero-posterior view, it is well to have the tube a good distance away from the plate, the greater the distance the better being the detail shown in the bones. The exposure has to be proportionately pro- longed, and if the tube is soft a longer exposure is further necessary. In examining the spine of children for curvature, etc., the author obtains good pictures by placing the tube four or five feet from the plate. Stereoscopic radiographs should always be taken of these spinal cases, as much more detail can be shown when they are examined in a stereoscope. This method is most useful in extensive caries of the spine when there is considerable deformity, as the picture is sharp, and fine changes in the bones can be detected. When the spine alone is required the diaphragm of the tube box should be closed down in order to get a long, narrow, slit-like aperture ; this ensures better detail in the parts required. The Lumbar Spine This is radiographed in the antero-posterior position, from the lower dorsal to the sacrum, by using a large extension tube with compression of the abdominal contents. It is an advantage in all positions of the spine, thorax, and abdomen, to diminish the movements of the parts as much as possible. The methods of compression employed are various. If working from below, it is an easy matter to have some simple form of compressor attached to the upper aspect of the couch. An air-cushion is placed between the patient and the couch to compress the abdominal contents. When using the tube above the couch, the compression may be obtained by fastening stout linen bands to the couch, carrying them round the patient, and fixing on the op- posite side. A long extension tube may be attached to the tube-holder, and fixed down on the patient by a mechanical device. These are all matters of detail which can be arranged to suit the individual worker, but whichever method is employed there can be no question of the great advantages of compression. PLATE V. — Normal Lumbar Spine and Pelvis. a. Normal lumbar spine. h. Normal male pelvis, c, Normal female pelvis. THE UPPER EXTREMITY 133 The Pelvis This region often requires most careful examination, for injuries, disease, or calculi. The positions are again two, antero-posterior and postero- anterior, both being useful. To get fine detail of the sacrum an extension tube is used, and it should be pressed well down into the pelvic cavity. The whole pelvis, with the heads of the femora and the acetabula, can be obtained by using a large plate behind the patient, or by placing the patient on the anterior surface with the plate underneath, the tube being placed above the posterior aspect of the patient. For the examination of the coccyx a small extension tube should be used, and the tube tilted forward into the cavity of the pelvis, the plate being placed on the posterior aspect beneath the patient. The Upper Extremity The Examination of the Clavicle. — The clavicle requires to be con- sidered in its whole length. Either extremity will appear in radiographs of the shoulder and of the thorax. The external end has frequently to be examined for displacements and injuries. The acromial end of the clavicle is seen in the several plates illustrating the shoulder-joint. Examination of the Shoulder-joint. — The shoulder- joint calls for minute description. It is frequently injured, and should be carefully exam- ined in all cases of suspected injury to that region. It is usually examined in the antero-posterior position, first with the plate on the posterior aspect of the joint with the tube in front, and then with the plate placed on the anterior aspect with the tube behind. It should always be examined in these two positions, if one is to demonstrate an injury in the shoulder-joint. The anti-cathode should be centred as nearly as possible over the coracoid process. An extension tube should be used, and slight pressure applied to the part. The pictures obtained by these two positions differ in several points of detail, the difierences being readily seen when the two radiographs are compared. The anatomical points seen in the pictures should be — (1) the head of the humerus ; (2) the glenoid cavity ; (3) the axillary border of the scapula; (4) the coracoid process ; (5) the acromion process ; (6) the acromial end of the clavicle. It is usual in such examinations to have the arm by the side. Supplementary skiagrams can be obtained by extending the arm out from the side or carrying it directly upwards in line with the long axis of the body. When it is necessary to examine the tuberosities the arm may be rotated in the direction necessary to show either one. Should the axillary border be suspected, the arm should be carried upwards and forwards and rotated outwards, so as to bring the body of the scapula away from the trunk. Plate VI., Fig. h shows the appearance of the parts when the plate is placed on the anterior aspect of the joint. The acromion process is best shown when the plate is placed on the 134 EADIOGEAPHY posterior aspect of tlie joint, with the tube in front, it beiag then possible to demonstrate the whole of the process and the spiae of the scapula, while the infra- and supra-spinous fossae can also be shown in their entirety. The coracoid process is well seen in all of the shoulder negatives, and changes in its position can be shown, fractures being readily demonstrated. When fine detail is necessary, and an injury is known to exist in the region of the coracoid process, a small picture should be obtained, an exten- sion tube being centred over the process, and the plate being either on the posterior or anterior aspect of the joint. The greater tuberosity of the humerus will be clearly shown. Its position and appearance will vary with the position of the shaft of the bone at the time, as regards rotation outwards or inwards. With the arm abducted and carried over the head, the shoulder- joint alters considerably in appearance. The head of the humerus and the glenoid cavity are well demonstrated, and the coracoid process is also well seen. The spine and body of the scapula are often investigated for evidence of fracture or tumour. The bone shows well in any of the usual positions, but if the vertebral border is under inspection, it is necessary to take a plate with the patient lying on it, and the arm abducted and carried upwards towards the head. The Elbow-joint. — Four positions are available in this joint, and each may be modified by the position in which the limb is placed at the time. (1) Antero-posterior, with plate on the front of the limb. (2) Antero-posterior, with plate on the back of the limb. (3) Lateral internal, with plate on the inner aspect of the joint, the arm being either flexed or extended. (4) Lateral external, plate on outer aspect of the joint, the forearm flexed or extended. Good pictures of the head of the radius and its articulation can be obtained by slightly flexing and pronating the forearm. The Radius and Ulna should always be taken in two positions : (1) lateral, (2) antero-posterior. The Wrist-joint must always be examined in two planes, the antero- posterior and the lateral. In both positions the tube is centred over the carpus. Compression on the limb may be effected by using a long extension tube, pads of lamb's wool being applied over the part, or sand-bags may be used to steady the limb. Metacarpal Bones and Phalang-es. — These frequently call for care- ful examination. Antero-posterior and lateral pictures may readily be obtained, but lateral pictures of the middle metacarpal bones are very difficult to obtain. The hand is placed obliquely on a plate, and the tube directed well in front of the middle line. The picture is somewhat distorted. Lateral views of the phalanges can be procured by placing a plate between the fingers. PLATE YI. — Normal Shoulder-joint. «, Normal shoulder -joint, plate on posterior aspect of joint. b. Normal shoulder-joint, plate on anterior aspect. c. Normal shoulder-joint, arm abducted. THE LOWER EXTREMITY 135 The Lower Extremity The bones of the pelvis are seen in most of the radiographs taken for the bladder and ureters. The sacrum is readily shown by putting a plate beneath the patient, and using a compression tube from above. In large pictures of the region the acetabula with the head of the femur are well shown. When the two joints are required for comparison, a good method is to radiograph the lower pelvis, centering the tube just below the symphysis pubis. Good detail is obtained of the head of the bones, and a good outline of the acetabulum. The iliac bones, which often require to be radiographed for fracture, tumour, etc., may be examined in two positions, with the tube centred over the middle of each bone, from the front. The Hip-joint is probably one of the joints most frequently examined. Two positions are available : (a) The posterior, when the plate is placed below the patient and the tube centred over the head of the bone. (6) The anterior, with the plate on the front of the joint and the tube centred behind. Both are useful, and either may give valuable information. The im- portant point is to make sure that good detail is obtained. This joint is the most difficult of all the joints from which to obtain good radiographs. A third position has already been described, where the plate is behind the patient and the tube centred just above the symphysis pubis. However obtained, a good radiograph should show the head of the femur, the cotyloid notch should be visible, the rim of the acetabulum should be seen superimposed over the head of the bone, and in normal joints the inter- articular space should be shown. The picture should include the greater and lesser trochanter and the upper third of the shaft of the femur. The ischium and pubis should come into the picture, as should also the lower half of the ilium. In some instances the limb may be abducted and rotated outwards to throw the head of the femur into prominence. The Shaft of the Femur may be taken in two directions, antero- posterior and lateral. Only the lower two-thirds can be seen in the latter position. When the whole bone is required long, narrow plates must be used, the tube requiring to be centred at a longer distance, in order to get the whole of the bone. The lateral view of the femur may be taken from either side. The Knee-joint. — This important joint requires careful examination. (a) Both knee-joints may be taken on one plate. The tube is centred over the space between the two joints, and either an anterior or posterior view may be obtained, (6) Plate on posterior aspect of joint, tube in front, (c) Plate on anterior aspect, tube behind. The patella is well seen by this method of examination. For the patella alone, the plate is placed on the front and the tube centred just outside the external border of the shaft, and directed obliquely down- 136 EADIOGEAPHY wards to avoid the shadow of the femur obscuring that of the patella. Plates taken in this position give good detail of the component parts of the joint. Fine detail should always be aimed at in these examinations. It is often possible to show apparently slight injury to the bone without an actual fracture. At a later date this may become the seat of chronic inflammatory changes, or tuberculosis of a joint may be a sequel to such an injury. The points to observe are the general contour of the articular surface, and the space between the condyles, which is usually occupied by cartilage, but which frequently does not show any detail of the articular surface, though plates taken with a very soft tube show shadowy detail of the cartilages and the softer structures of the joint. The normal position of the patella, the articular surface of the upper end of the tibia, and the spine of the tibia should be noted. This is of great importance, for when cases are examined for injuries of the joint we must not overlook the relations of these parts to one another. (d) The lateral view of the knee-joint is the most useful one from the point of view of diagnosis. In it we see the relations of the bony surfaces and a faint line of the articular cartilage, while in some instances the shadow of the internal articular cartilage is seen in a very faint, somewhat striated shadow. The outline of the patella is sharp and clearly cut, the pad of fat below the patella is frequently shown, and the Ugamentum patellae can be traced from the lower edge of the patella to its insertion into the tuberosity of the tibia. The two condyles of the lower end of the femur are clearly seen, and the head of the fibula with its articulation to the tibia is also shown. This view of the knee-joint may be taken from either side — internal or external. The Tibia and the Fibula. — These bones may be radiographed from the front or the back, or laterally, from the inner or outer aspects of the limb. The Ankle-joint. — There are four positions for the examination of this joint : (a) Anterior, plate on the front of the limb. (6) Posterior, plate on the posterior aspect of the limb, the foot at right angles to the leg. (c) Lateral internal. (d) Lateral external. The Bones of the Foot : Tarsal, Metatarsal, and Phalang-es. — For a general survey of the foot, the plate may be placed upon the inner aspect and the tube centred over the mid-point between the os calcis and the end of the toes. By making another exposure the outer aspect of the foot may be brought into closer contact with the plate. The OS calcis can be examined in three positions : (1) In the lateral position, plate on outer aspect of foot (2) Lateral aspect, plate on inner side of the foot. (3) With a plate placed mider the foot, the patient standing upon it, the tube being centred behind the bone, well above the insertion of the tendo THE FOOT 137 Acliillis, and directed obliquely downwards and forwards. A good view of the whole bone may be obtained in this way. To obtain a reliable radiograph of the metatarsus and phalanges, the foot is placed upon the plate and the tube is directed downwards and slightly towards the heel. The patient may stand upon the plate ; or if he is lying on the back, the knee-joint is flexed, and the plantar aspect of the foot is placed in contact with the plate. THE DEVELOPMENT OF THE BONES The importance of this section is great, as it is necessary to know the details of ossification and union of these bones. The following descriptions and drawings are based on those from well-known works on anatomy. The dates given are those which have long been recognised as the correct ones, but it is quite probable in the near future that many of those quoted may have to be revised as a result of systematic investigation on bone ossification by means of X-ray examinations. It is possible by this means to ascertain accurately the normal dates of union, but until the work of X-ray examination has been completely carried out it will be necessary to use the work of the anatomist. The chief times of union need only be considered in those bones which are most likely to be injured. The ends of the long bones, the scapula, and the pelvis chiefly interest the radiographer. The usefulness of a complete though necessarily short description cannot be overestimated. Diagrams and skiagrams will be used to illustrate changes, though it is obviously impossible to include examples of the epiphyses at all ages. It is hoped that this section will be found useful for reference, as it is hardly possible for the radiographer to carry all the dates in his mind. The Clavicle. — Commencing with the bones of the upper extremity, we note that this bone is developed from three centres, two for the shaft and one for the sternal extremity. The centre for the shaft appears very early, before any other hone ; according to Beclard, as early as the thirtieth day. The centre for the sternal end makes its appearance about the eighteenth or twentieth year, and unites with the rest of the bone about the twenty-fifth year. The Scapula. — Development takes place by seven centres: one for the body, two for the coracoid process, two for the acromion, one for the pos- terior border, and one for the inferior angle. Ossification of the body of the scapula commences about the second month of foetal life by the formation of an irregular plate of bone immediately behind the glenoid cavity. This plate extends itself so as to form the chief part of the bone, the spine growing up from its posterior surface about the third month. At birth the chief part of the scapula is osseous, the coracoid and acromion processes, the posterior border and inferior angle being cartilaginous. About the first year after birth ossification takes place in the middle of the coracoid process, which 138 PLATE VII. — Normal Elbow and Fractures in Region of Elbow-joint. a, Normal elbow-joint, antero-posterior loositiou. b, Injury to epiphysis of olecranon. c, Normal elbow-joint, lateral position. d, Fracture through olecranon process. THE UPPER EXTREMITY 139 usually becomes joined with the rest of the bone at the time when the other centres make their appearance. Between the fifteenth and seventeenth years ossification of the remaining centres takes place in quick succession, and in the following order : first, near the base of the acromion and in the root of the coracoid process, the latter appearing in the form of a broad scale ; secondly, in the inferior angle and contiguous part of the posterior border ; thirdly, near the extremity of the acromion ; and fourthly, in the posterior border. The acromion process, besides being formed of two separate nuclei, has its base formed by an extension into it of the centre of ossification which belongs to the spine, the extent of which varies in different cases. The two separate nuclei unite, and then join with the extension carried in from the spine. These various epiphyses become joined to the bone between the ages of twenty-two and twenty-five years. Sometimes failure of union between the acromion process and spine occurs, the jmiction being formed by fibrous tissue or by an imperfect articulation. In some cases of supposed fracture of the acromion with ligamentous union it is probable that the detached segment was never united to the rest of the bone. The Humerus. — Development takes place by eight centres : one for the shaft, one for the head, one for each tuberosity, one for the radial head, one for the trochlear portion of the articular surface, and one for each of the condyles. The nucleus for the shaft appears near the centre of the bone in the eighth week, and soon extends towards the extremities. At birth the humerus is ossified nearly in its whole length, the extremities remaining cartilaginous. At the beginning of the second year ossification commences in the head of the bone, and during the third year the centre for the tuberosities makes its appearance usually by a single ossific point, but sometimes, accord- ing to Beclard, by one for each tuberosity, that for the lesser being small and not appearing until after the fourth year. By the fifth year the centres for the head and tuberosities have enlarged, and become joined so as to form a single large epiphysis. The lower end of the humerus is developed in the following manner : — ^At the end of the second year ossification commences in the radial portion of the articular surface, and from this point extends inwards, so as to form the chief part of the articular end of the bone, the centre for the inner part of the articular surface not appearing until about the age of twelve. Ossification commences in the internal condyle about the fifth year, and in the external one not until about the thirteenth or fourteenth year. At about sixteen or seventeen years the outer condyle and both portions of the articulating surfaces (having already joined) unite with the shaft. At eighteen years the inner condyle becomes joined, whilst the upper epiphysis, although the first formed, is not united until about the twentieth year. The Ulna. — Development takes place by three centres : one for the shaft, one for the inferior extremity, and one for the olecranon. Ossification commences near the middle of the shaft about the eighth week, and soon extends through the greater part of the bone. At birth the ends are carti- laginous. About the fourth year a separate osseous nucleus appears in the 140 KADIOGEAPHY middle of the head, which soon extends into the styloid process. At about the tenth year ossific matter appears in the olecranon near its extremity, the chief part of this process being formed from an extension of the shaft into it. At about the sixteenth year the upper epiphysis becomes joined, and at about the twentieth year the lower one. The Radius. ^ — ^Development takes place by three centres, one for the shaft and one for each extremity. That for the shaft makes its appearance near the centre of the bone, soon after the development of the humerus commences. At birth the shaft is ossified, but the ends of the bone are cartilaginous. About the end of the second year ossification commences in the lower epiphysis, and about the fifth year in the upper one. At the age of seventeen or eighteen the upper epiphysis becomes joined to the shaft, the lower epiphysis becoming united about the twentieth year. The Bones of the Hand. — The carpal bones are each developed by a single centre. At birth they are all cartilaginous. Ossification proceeds in the following order : in the os magnum and unciform an ossific point appears during the first year, the former preceding the latter ; in the cunei- form, at the third year ; in the trapezium and semilunar, at the fifth year, the former preceding the latter ; in the scaphoid, at the sixth year ; in the trapezoid, during the eighth year ; and in the pisiform, about the twelfth year. The metacarpal bones are each developed by two centres, one for the shaft and one for the digital extremity, for the four inner metacarpal bones ; one for the shaft and one for the base, for the metacarpal bone of the thumb, which in this respect resembles the phalanges. Ossification commences in the shaft about the eighth or ninth week, and gradually proceeds to either end of the bone. About the third year the digital extremities of the four inner metacarpal bones and the base of the first metacarpal bones commence to ossify, and they unite about the eighteenth year. The phalanges are each developed by two centres, one for the shaft and one for the base. Ossification commences in the shaft in all three rows at about the eighth week, and gradually involves the whole of the bone except- ing the upper extremity. Ossification of the base commences between the third and fourth years, and a year later in those of the second and third rows. The two centres become united in each row between the eighteenth and twentieth years. The Os Innominatum is a large, irregularly shaped bone, which, with that of the opposite side, forms the sides and anterior walls of the pelvic cavity. In yomig subjects it consists of the separate parts which meet and form the large cup-shaped cavity situated near the middle of the outer side of the bone ; and although in the adult these have become united, it is usual to describe the bone as divisible into three portions : the ilium, the ischium, and the pubes. Development takes place by eight centres : three primary, one for the ilium, one for the ischium, and one for the pubes ; and five secondary, one for the crest of the ilium, one for the anterior inferior spinous process (said to occur more frequently in the male than in the female), one for the tuberosity of the ischium, one for the symphysis pubis (more PLATE VIII. — Normal Knee-joint. a, Normal knee-joint, lateral view. h, Knee-joint in young adult, irregularity in region of tubercle of tibia. c, Normal knee-joint, antero-posterior. THE LOWER EXTREMITY 141 frequent in the female than in the male), and one for the Y-shaped piece at the bottom of the acetabulum. These various centres appear in the following order : (a) in the ilium, immediately above the sciatic notch, at about the same period as the develop- ment of the vertebrae commences ; (b) in the body of the ischium, at about the third month of foetal life ; and (c) in the body of the pubes, between the fourth and fifth months. At birth the three primary centres are quite separate, the crest, the bottom of the acetabulum, and the rami of the ischium and pubes being still cartilaginous. At about the seventh or eighth year the rami of the pubes and ischium are almost completely ossified. About the thirteenth or fourteenth year the three divisions of the bone have extended their growth into the bottom of the acetabulum, being separated from each other by the Y-shaped portion of cartilage, which now presents traces of ossification. The ilium and ischium then become joined, and lastly the pubes, through the intervention of the Y-shaped portion. At about the age of puberty ossification takes place in each of the remaining portions, and they become joined to the rest of the bone about the twenty-fifth year. It is important to bear in mind the development of the bones entering into the hip-joint, as this region has to be frequently examined for injuries and disease. The FemuF. — The femur is developed by five centres : one for the shaft, one for each extremity, and one for each trochanter. Of all the long bones except the clavicle it is the first to show ossification ; this commences in the shaft about the fifth week of foetal life, the centres of ossification appear- ing in the epiphyses in the following order : first in the lower end of the bone at the ninth month of foetal life — from this the condyles and tuberosities are formed ; in the head at the end of the first year of birth ; in the great tro- chanter during the fourth year ; and in the lesser trochanter between the thirteenth and fourteenth years. The order in which the epiphyses are joined to the shaft is the reverse of that of their appearance ; their junction does not commence until after puberty, the lesser trochanter being first joined, then the greater, then the head, and lastly the inferior extremity (the first in which ossification commenced), which is not united until the twentieth year. The Patella. — ^Development takes place by a single centre, which makes its appearance about the third year. In two instances it has been seen cartilaginous throughout at a much later period (six years). More rarely the bone is developed by two centres placed side by side. Ossification is completed about the age of puberty. The Tibia. — -Development takes place by three centres, one for the shaft and one for each extremity. Ossification commences in the centre of the shaft about the seventh week, and gradually extends towards either extremity. The centre for the upper epiphysis appears at birth. It is flattened in form, and has a thin tongue-shaped process in front, which forms the tubercle. That for the lower epiphysis appears in the second year. The lower epiphysis joins the shaft at about the eighteenth, and the upper one about the twentieth year. Two additional centres occasionally exist : one 142 RADIOGKAPHY for the tongue-shaped process of the upper epiphysis, the tubercle, and one for the inner malleolus. The Fibula. ^ — Development takes place by three centres, one for the shaft and one for each extremity. Ossification commences in the shaft about the eighth week of foetal life, a little later than in the tibia, and extends gradually towards the extremities. At birth both ends are cartilaginous. Ossification commences in the lower end in the second year, and in the upper one about the fourth year. The lower epiphysis, the first in which ossifica- tion commences, becomes united to the shaft first, contrary to the law which appears to prevail with regard to the junction of epiphysis with diaphysis. This takes place about the twentieth year. The upper epiphysis is joined about the twenty-fifth year. The Bones of the Foot. — The tarsal hones are each developed by a single centre, excepting the os calcis, which has an epiphysis for its posterior extremity, just below the insertion of the tendo Achillis. It is seen as a small oval disc. The centres make their appearance in the following order : os calcis, at the sixth month of foetal life ; astragalus, about the seventh month ; €uboid, at the ninth month ; external cuneiform, during the first year ; internal cuneiform, in the third year ; middle cuneiform and scaphoid, in the fourth year. The epiphysis for the posterior extremity of the os calcis appears at the tenth year, and unites with the rest of the bone soon after puberty. The metatarsal hones are each developed by two centres : one for the shaft and one for the digital extremity in the four outer metatarsals ; one for the shaft and one for the base in the metatarsal bone of the great toe. Ossifica- tion commences in the centre of the shaft about the ninth week and extends towards either extremity, and in the digital epiphysis about the third year ; they become joined between the eighteenth and twentieth years. The ■phalanges are developed by two centres for each bone, one for the shaft and one for the metatarsal extremity. The Hyoid Bone is a bony arch, shaped like a horse-shoe, and is of a quadrilateral form. Development takes place by six centres, two for the body and one for each cornua. Ossification commences in the body and greater cornua towards the end of fcetal life, the centres for the cornua first appearing. Ossification at the lesser cornua commences some months after birth. The Sternum is a flat narrow bone, situated in the median line in the front of the chest, and consisting in the adult of three portions — the manu- brium, the gladiolus, and the ensiform or xiphoid appendix. The sternum, including the ensiform appendix, is developed by six centres — one for the first piece or the manubrium, four for the second piece or gladiolus, and one for the ensiform appendix. Up to the middle of foetal life the sternum is entirely cartilaginous, and when ossification takes place the ossific granules are deposited in the middle of the intervals, between the articular depressions for the costal cartilages, in the following order : in the first piece, between the fifth and sixth months ; in the second and THE TRUNK 143 third, between the sixth and seventh months ; in the fourth piece, at the ninth month ; in the fifth, within the first year, or between the first and second years after birth ; and in the ensiform appendix, between the second and the seventeenth and eighteenth years by a single centre, which makes its appearance at the upper part and proceeds gradually doAvnwards. To these may be added the occasional existence, as described by Breschet, of two small episternal centres, which make their appearance, one on each side of the sterno-clavicular notch. These are regarded by him as the anterior rudiments of a rib, of which the posterior rudiment is the anterior lamina of the transverse process of the seventh cervical vertebra. It occasionally happens that some of the segments are formed from more than one centre, the number and position of which vary. Thus the first piece may have two, three, or even six centres. When two are present, they are generally situated one above the other, the upper one being the larger. The second piece has seldom more than one. The third, fourth, and fifth pieces are often formed from two centres, placed laterally, the irregular union of which will serve to explain the occasional occurrence of the sternal foramen or of the vertical fissure which occasionally intersects this part of the bone. Union of the various centres commences from below and proceeds upwards, taking place in the following order : the fifth piece is joined to the fourth soon after puberty ; the fourth to the third between the twentieth and twenty-fifth years ; the third to the second between the thirty-fifth and fortieth years ; the second is occasionally joined to the first, especially at an advanced age. Ossification of the Skull and the Vertebral Column. — It is unnecessary to deal extensively with the development of these bones. In the vertebral column each vertebra is ossified from three centres, two for the vertebral arch and one for the body. About the sixteenth year five secondary centres appear : one for the extremity of each transverse process, one for the extremity of the spinous process, one for the upper and one for the lower surface of the body. These fuse with the rest of the body about the age of twenty -five years. These are the main points in the ossification of the vertebral column ; but there are exceptions in the case of the first, second, and seventh cervical, and in the lumbar vertebrae. The atlas is usually ossified from three centres. The axis is ossified from five primary and two secondary centres. The seventh cervical varies in its departures from the normal. A cervical rib is due to a persistence as a separate piece of the costal part, which becomes lengthened laterally and forwards. The lumbar vertebrae have each two additional centres for the mammillary processes. The transverse process of the first lumbar is sometimes developed as a separate piece, which may remain permanently un-united with the rest of the body, thus forming a lumbar rib, a peculiarity rarely met with. 144 EADIOGEAPHY Radiographic Survey of the Joints showing Epiphyses The Ankle-joint. — The lower epiphyses of the tibia and fibula are best seen in an antero-posterior view of the joint. The epiphyseal line is nearly horizontal in the case of both bones, but that of the fibula is at a lower level and comes opposite the ankle-joint. The internal malleolus forms the inner portion of the lower tibial epiphysis, while the external malleolus is practically Appears at^ 2mJ year Joins body about 20Vyr Appears^ at Z^-^yr. lUnites about IZOthyr Fig. 111. — Showing bones at ankle and foot with epipliyses, and dates at which they unite with the diaphyses. Appears at 3 '■-"_>' r ■Joins 18*-'' to20*-^yrs. Appears ytl'week. entirely composed of the lower epiphysis of the fibula. The latter epiphysis is greatly concerned in the increase in length of the fibula. Table of Development of the Taesus The tarsal bones develop by a single centre. Os calcis .... They appear approximately as follows : — . Sixth month of foetal life. Sometimes this bone develops from two or three centres of ossification. Astragalus .... Seventh month of foetal life. Ninth month of foetal life. First year. Third year. Cuboid External cuneiform Internal cuneiform Sliddle cuneiform Scaphoid . Fourth year. Fourth year. The ossific centre for the epiphysis of the os calcis appears at the ninth year, and may sometimes unite before puberty. It may develop from two centres. THE KNEE-JOINT U5 Fig. 112.— Foot. Antero-posterior view, plantar aspect of foot on plate. Age 14. Knee-joint. — The epiphyses entering into the formation of this joint are of the'greatest importance, for it is one of the joints most frequently injured. Appears 9*^ month of foetal life Lower end of femur. Upper end of tibia. Upper.end of fibula. Fig. 113. — Diagram to show the epiphyses entering into the knee-joint. The epiphysis of the lower end of the femur is the only one in which bone is formed before birth. 10 146 RADIOGRAPHY In an antero-posterior view it is seen as a large irregular bony mass, Antero-posterior. Lateral. Fig. 114. — Diagrams to illustrate the appearances of the epiphyses at the knee-joint, traced from radiographs. forming the entire lower end of the femur. Bpiphyspal line i^ss^m/fi^mKm I Patella Tubercle of Tibia Fig. 115. — Lateral view of knee-joint, showing epiphyses. Note prolongation of tibial epiphysis on anterior aspect of tibia. Age, 14 years. The epiphyseal line is seen at the level of the adductor tubercle on the inner side. It is wavy in out- line, rises sharply towards the centre, and has a slightly lower level at the outer side of the bone. The epiphyses of the tibia and fibula will be seen in the picture. The epiphyseal line of the tibia resembles that of the line of the lower end of the femur. The upper epiphysis of the fibula is a small mass, appearing to rest on the top of the shaft. PLATE IX. — Showing Epiphyses of Hip, Knee, and Ankle Joints. a, Pelvis and hip-joints in a child of 5-6 years. Knee-joint in a child 10-12 years, b, Lateral view, c, Antero-posterior view. Ankle-joint in a child 10-12 years, d, Lateral aspect, e, Antero-posterior aspect. THE KNEE-JOINT 147 In a lateral view the epiphyseal lines of the femur aad fibula are nearly Lines of Iracture Head of Fibula Fig. 116. — Antero-posterior view of knee-joint showing epiphyses. Plate on posterior aspect of joint. Fig. 117. — Fracture of tibia and fibula. Practically no displace- ment. The appearances of the epiphyses at both ends of the bones indicate the age of the patient to be about 3 years. The fibula has a convexity to- wards the tibia. horizontal. The epiphysis of the upper end of the tibia is seen to have a tongue - like projec- tion extending down the front of the bone to the tubercle of the tibia. In some instances this projec- tion does not reach so far as the tubercle, and the latter is seen arising from a separate centre of ossification. It is fre- quently the seat of in- jury and inflammation (see Plates VIII. Fig. h, and XVIII. Fig. a). The Hip -joint, pjq — The epiphysis of the upper end of the femur includes merely the articular head of Symphy,,. 118. — Diagram to show the epiphyses and bones entering into the hip-joint. 148 KADIOGRAPHY the bone and forms no part of the neck. In an X-ray picture it resembles somewhat the appearance of the epiphysis of the upper end of the humerus. The greater and lesser trochanters arise from separate centres of ossification, but these are less frequently seen in radiographs than is the larger epiphysis (see Plate IX. a). Upper end of shaft of femur Epiphyses for head have not yet appeared Epiphysis for lower end of femur Fig. 119. — Pelvis and femora of a child two days old, showing ossification of bones of pelvis, hip and knee j oints. Note lower epiphyses of femur present at birth. The Wrist-joint. — -The epiphysis of the lower end of the radius is seen in an antero-posterior view of the joint as a wedge-shaped shadow, and is thicker on the outer than on the inner side of the wrist. The epiphyseal line, though irregular and wavy, is never rough and jagged as in a fracture. This epiphysis has a great share in the increase in length of the shaft. The epiphysis of the lower end of the ulna is seen at a higher level than that of the radius and shows the prominence of the styloid process on its inner side. The centres of ossification for the carpal bones show according to the age at which the joint is examined (see " Ossification "). THE WRIST-JOINT 149 Table of Ossification for Carpal Bones The carpus is entirely cartilaginous at birth, at the following times : Centres appear for these carpal bones Os magnum Unciform Cuneiform Semilunar first year, second year, third year, fifth year. Trapezium Scaphoid Trapezoid Pisiform fifth year, seventh year, eighth year, twelfth year. The " OS central," lying between the bones of the first and second rows, is present in man as a small cartilage situated between the " trapezoid," trapezium, os magnum, and " scaphoid," at the second month, and disappears about the fourth month of foetal hfe. In rare cases it persists as a separate bone in the adult. ^ ' Appears 3':?^r. Appears 3-4'-''yr Urates l8-20«^>r ^ lj£;^Appe3re 4.-5'-"yr. ■ es IS-ZO'Iyr. IS-ZO'^'^r ('Appeal Fig. 120. — Diagram showing ossification of the bones of the hand and the wrist-joint witli the times of union of epiphyses with diaphyses. Fig. 121. — Hand of a child over five years old. Shows development of bones of lower ends of radius and ulna, carpal bonts, metacarpals, and phalanges. The epiphysis for lower end of radius well developed. The ulnar epiphysis has not yet appeared. The os magnum and unciform, semi- lunar and cuneiform bones are also shown. The pisiform is not shown. Note also the centre for the proximal end of the metacarpal bone of the thumb. The epiphyses of the four inner metacarpal bones are seen at the distal ends of the shafts, but in the phalanges and in the metacarpal bone of the thumb the epiphyses are found at the proximal ends of the respective bones. 150 EADIOGRAPHY Fig. 122. — Shows stage of ossification in a young adult under twenty years. The Elbow-joint. — The lower epiphysis of the humerus at the age of five or six years merely shows the centre for the capitulum as a small round mass. In an antero-posterior picture of the joint it is seen as a wedge- FlG. 123. — Diagram showing epi- ■-" ------ physes of the bones forming the Fig. 124. — Elbow-joint, antero-posterior view, shows epiphyses, elbow-joint. Age 14. shaped mass, its lower surface being convex, and lying below the external condyle. At twelve the centres for the trochlea and the external epicon- THE ELBOW AND SHOULDER JOINTS 151 Olecranon Shaft of Ulna Fig. ]25. — Lateral view of elbow-joint, to show epiphyses. Age 14. dyle have appeared, and have united with the centre for the capitulum, forming the lower epiphysis. The lower end of the humerus Ls one of the bones most frequently involved in injuries and disease, but the other bones entering into the joint should also be remembered in relation to the times at which their epiphyses join the diaphyses. The internal epicondyle is not a part of the lower epiphysis of the humerus, but is formed from a separate centre of ossification. In an X-ray picture it is seen as a small, oval mass, higher up on the inner side of the humerus, and intimately connected with the internal condyle. The epiphysis of the head of the radius is seen as a small disc, just above the upper end of the bone. In a lateral view of the joint at about five years the lower epiphysis of the humerus appears to be semilunar in shape, fitting closely to the lower end of the shaft. At a later age the parts become accentuated, and great care must be exercised in dis- tinguishing the normal appearances when ex- amining the joint for suspected injuries. A normal radiograph should always be com- pared with the sus- pected one if mistakes are to be avoided. The Shoulder - joint. — The upper epi- physis of the humerus is found as a dome- shaped mass, which appears to rest on the top of the shaft. It is composed of the , , centres for the head Fig. 126. — Diagram to show bones entering into the shoulder- i <■ i n joint. The clavicle has not been included. and for the greater and Humerus Head of Radius .^2 for coracoid process. Epiphyses of head / <'>y Situbercles blend at Sthyr and unite with bodyat20l')yf 152 KADIOGKAPHY lesser tuberosities, which unite to form the epiphysis. The epiphyseal line lies a little way above the surgical neck, and is not horizontal, but is higher in the middle of the shaft than at the outer and inner sides. The increase Fig. 127. — Normal shoulder-joint showing condition of epiphyses at the head of humerus. in length of the humerus takes place principally at this epiphysis, and hence its great importance. Certain anatomical facts are worthy of note when we are considering inflammatory conditions and injuries of the bones iti the neighbourhood of joints, more especially in children and young adults. It is important to keep in mind the chief centres of ossification and the periods at which the epiphyses join the diaphyses in the joints most liable to injury ; but as it is obvious that one cannot readily recall the whole of them it is hoped that a refer- ence to the foregoing pages j^^j^, , \ . / , .'" . , , ,. will be helpful. The marked Fig. 128. — Shoulder-joint, .showing epiphyseal line. _ ^ Centres for head and great tuberosity have joined. There differences between the appcar- is evidence of a partial fracture at the surgical neck. ^^^^^ ^^ .^.^^^ -^ ^^^j^ ^^^^-^ and in adult life must be noted to avoid errors in diagnosis. Fractures are relatively more frequent in adults, while greenstick fracture and separation of epiphyses are more prevalent in injuries occurring before the epiphyses have joined up with the diaphyses. SESAMOID BONES 153 The after history of an injury is greatly influenced in its results when the injury occurs in the neighbourhood of the epiphyseal line. Arrested develop- ment is a frequent result of such an injury. There are, therefore, certain points which should be remembered in relation to the principal joints of the body which will be briefly mentioned, reference to figures illustrating these points being made as occasion arises. Sesamoid Bones. — These are small rounded masses, cartilaginous in early life, osseous in the adult, which are developed in tendons which exert a great amount of pressure upon those parts over which they glide. It is said that they are more commonly found in the male than in the female, and in persons of an active muscular habit than in those who are weak and debilitated. They have a free articular facet. The sesamoid bones of the joints in the lower extremity are : the patella, in the tendon of the quadriceps extensor ; two small sesamoid bones in the tendon of the flexor brevis pollicis, opposite the metatarso-phalangeal joint of the great toe ; and occasionally one at the metatarso-phalangeal joint of the second toe, of the little toe, and, still more rarely, of the third and fourth toes. In the knee-joint posteriorly there may also be one. In the upper extremity they are found on the palmar aspect of the metacarpo- phalangeal joint in the thumb, developed in the tendon of the flexor brevis pollicis, occasionally one or two opposite the metacarpo- phalangeal articulations of the fore and little fingers, and still more rarely one opposite the corresponding joints of the third and fourth fingers. Those found in the tendons, which glide over certain bones, occupy the following positions: one in the tendon of the peroneus longus, where it glides through the groove in the cuboid bone ; one which appears later in the tendon of the tibiahs anticus, opposite the smooth facet on the internal cuneiform bone ; one is found in the tendon of the tibialis posticus, opposite the inner side of the astragalus ; one in the outer head of the gastroc- nemius behind the outer condyle of the femur, and one in the psoas and iliacus, where they glide over the body of the pubes. Sesamoid bones are found occasionally in the tendon of the biceps, opposite the tuberosity of the radius ; in the tendon of the glutseus maximus, as it passes over the great trochanter, and in the tendons which wind round the inner and outer malleoli. INJURIES OF BONES AND JOINTS The methods which are employed for the determination of injuries of bones and joints are (1) fluoroscopy, (2) radiography. Both should be employed, the former for the determination of the presence of an injury and for the purpose of centering the tube under the injured part. In regard to diagnosis by screening only a few words of caution are necessary. While in a number of gross lesions with a degree of displacement and dislocations it is possible to make a positive diagnosis at once, it must be pointed out that a negative diagnosis of injury to bone should never be made on the screen examination alone. A plate should always be exposed after the screen examination has been made if the operator has not been able to detect an injury. If this procedure is followed it is possible to avoid making many serious errors in diagnosis. Fractures of the phalanges when there is no displacement are frequently unrecognisable under the screen. Crushing of the bones in the neighbourhood of a joint, sprain, fractures, and many so- called trivial injuries to bones and joints will be overlooked if the radio- graphic method is not employed. The examination of the bones and joints in the normal individual is comparatively easy, in the injured patient it is often a matter of extreme diflS.culty to adjust the tube and plate. Great ingenuity may have to be displayed in certain cases. The best method to employ is to place the patient upon a radiographic couch. It is convenient to have a good supply of cushions, air-bags, and sand-bags in order to get a position of comparative ease for the patient. Many patients complain of the hardness of the X-ray couch. The tube should be accurately centred in the tube-box, and its focus point should be capable of ready adjustment by movements in two directions under the couch. With a plumb line it is possible to quickly centre the tube under the central point of a joint or bone. Injuries of the Skull and Spine The skull is frequently examined for evidence of fracture. Fractures may occur at the base, when they can be recognised by departures from the normal on a lateral or antero-posterior radiograph. Both positions should be taken. In children, when the sutures are very evident, care must be exercised to distinguish between these and a fracture. In the region of the temporal bone this is most important. 154 FRACTURES OF THE SKULL 155 Fracture of the Vault of the Skull.— A depressed fracture can readily be detected when a lateral view of the skull ls taken. The extent of the injury and the degree of depression should be noted. Fracture at the base of the skull is difficult to determine. It may occur at any part of the base and may be represented as a fine fissure in the bone. When this occurs in the neigh- bourhood of the sutures it is often impossible to make a positive statement as to the nature of an injury. In children where the sutures have not closed it is still Fig. 129. — (Jommiuutbd fracture of augle of lower jaw. This skiagrani shows the teeth, particularly the roots in the lower jaw. The inferior dental canal is seen running along the jaw. tooth shows extensive caries. One more difficult. In doubtful cases stereoscopic radio- FiG. 130. — Fracture through ramus of lower jaw. The soft parts show well. graphs should be taken. CHnical signs should always be taken into account. 156 EADIOaRAPHY Fractures in the Orbital Region are very difficult to distinguish. Fine detail must be obtained, and care should be exercised to obtain radio- graphs which show no evidence of movement on the part of the patient. This is often a matter of difficulty, because patients suffering from injury to the skull and brain are not likely to keep the head steady long enough to allow of a sufficient exposure; hence in these cases very rapid expo- sures are indicated, and intensifying screens should be used to cut down the exposure to the minimum. The orbital margins should be carefully examined to detect slight departures from the normal, which may be the only evidence of fracture. The Zygfomatic Arch is occasionally broken. There may be a depression of the bone, this being readily de- tected when an antero- posterior radiograph is obtained. Fracture of the Superior Maxilla. — This may occur in head injuries, or a tooth may be driven into the an- trum of Highmore. The palatine arch may be disturbed. Careful examination of the radiograph is necessary when injuries in this region are suspected. Fracture of the Inferior Maxilla (Man- dible).— This bone is frequently injured. Three positions are available: (1) antero-posterior ; (2) lateral ; (3) film in the mouth. The condyle may be injured when the bone is subjected to direct violence. The coronoid process may be fractured either by direct or indirect violence. It is somewhat difficult to get a goodradiographof one side of the lower jaw, because of the superimposing of the shadows. Probably the best method to em- ploy is to centre the tube behind and a little below the angle of the jaw. With the plate on the injured side, the tube is centred over a spot behind and below the angle of the uninjured jaw, thus avoiding the overlapping of the latter. By using the above method it is possible to obtain a picture of the side required, showing the whole of the lower jaw in profile, the temporo-maxillary articulation being well shown. This is also a useful method when it is neces- sary to examine the jaw for tumour or dental disease. Fractures of the Nasal Bones. — These are occasionally fractured on one or both sides. A plate on the injured side is generally sufficient to show Fig. 131. — Fracture dislocation of cervical vertebrae. PLATE X. — Fractures in Region of the Shoulder-joint. a, Fracture through great tuberosity. h, Exostosis of angle of scapula. c, Fracture (stellate) of body of scapula ; the detail has been lost in reproduction. d. Fracture at upper end of shaft of humerus, there is no displacement. Note the epiphyseal line of head of humerus. FRACTURES OF THE VERTEBRAE 157 the injury. An antero-posterior view is also useful. Stereoscopic pictures may be necessary. A small piece of X-ray film placed in contact with the side of the nose will give a sharp picture. Injuries of the Cervical Vertebrae. — Two positions have already been described. The lateral is the most useful, for it shows readily very slight departures from the normal. Fracture dislocation of the cervical vertebrae is a not uncommon in- jury. Any part of the cervical region may be the seat of a dislocation. The appearances are unmistakable when well marked, but the doubt- ful cases give rise to considerable difficulty in diagnosis. Fig. 131 illustrates a partial frac- ture dislocation of the upper cervical vertebrae, which was not definitely diagnosed for several weeks after the injury occurred. Injuries of the Dorsal Vertebrae. — The dorsal spine may be involved in injuries of the thorax. Ribs may be fractured and the ver- tebral column crushed, or partial dislocation may be present. Two positions are useful : (1) a postero-anterior, that is, the plate on the back and the tube in front ; (2) a lateral, to show the bodies of the verte- brae. It is often ex- tremely difficult to show fractures of the posterior parts of the spinal column. Crushing and displacement of the bodies may be clearly indicated. Fracture of the transverse process sometimes occurs. When there is considerable displacement it is possible to demonstrate the position of the lesion. Fig. 132.- Fractures of vertebral border of scapula and three ribs (gunshot wound). Fracture of the Ribs The demonstration of fracture of the ribs is often a matter of great difiiculty. This is particularly so when the bone is broken through and no displacement takes place. When there is considerable displacement the fracture shows up readily. The best positions for showing fractures of these 158 KADIOGRAPHY bones are antero-posterior and lateral. The latter is often a difficult position in which to show a fracture, especially in stout patients. Fracture of the Clavicle (1) At the acromial end external to the trapezoid ligament, usually pro- duced by direct violence. The inner fragment retains its position unaltered, but the outer fragment is dragged down by the weight of the arm, and for- wards by the action of the muscles, so that it lies at right angles to the rest of the bones. (2) Between the coraco-clavicular ligaments. There is little displace- ment. It may be shown radiographically as a fissured fracture of the bone. (3) Through the greater convexity of the bone. There is frequently considerable displacement. (See Plate XL Fig. d.) (4) At the sternal end. This may be complicated by a partial dis- placement. (5) Greenstick fracture of the clavicle, a common injury in children. Frequently only a decided bend on the bone is seen, but occasionally a minute crack may be detected. Fracture of the Scapula The Body of the scapula may be broken in cases of injury due to direct violence, the fracture being usually of the fissured or stellate variety when the flat surface of the bone is damaged. The vertebral border is occasionally involved in these injuries. The Spine of the scapula may also be fractured, generally as the result of direct violence. The Acromion Process may be broken by direct violence applied to the point of the shoulder. The arm hangs powerless by the side, and the shoulder is flattened. The irregularity of the bone can be readily detected. and crepitus can be elicited by raising the elbow and rotating the arm. Occasionally merely the tip is detached, and then the above signs will not be present. The Coracoid Process is rarely fractured, and only from direct violence. There is but little displacement, on account of the many powerful ligaments attached to it. In spite of the attachment of such powerful muscles as the pectoralis minor, biceps, and coraco-brachialis, the displacement is not great, as the process is kept' in position by the coraco-clavicular ligament. The Neck of the scapula may be fractured immediately behind the glenoid cavity, but this is a rare injury. Its existence has been doubted. Astley Cooper and South have stated that cases so described are in reality fractures of the upper end of the humerus. There is, according to South, no specimen in any of the London museums illustrating fracture of the neck of the scapula (Erichsen). Walsham describes one case of this variety of fracture which is in Guy's Hospital museum, and Rose and Carless figure an instance of this variety. It is usually due to direct violence ; a portion of the PLATE XL — Fractures in Kegion of Shoulder-joint. a, Fracture at upper end of humerus, a longitudinal splitting of the shaft with head displaced forwards and downwards (dislocation of the head). h, Separation of the great tuberosity of the humerus. c, Fracture through lower aspect of glenoid cavity. d, Fracture of the clavicle (nnddle third), the base of the acromion process is irregular and appears to be fractured. FRACTURES OF THE SCAPULA AND HUMERUS 159 articular surface is broken off and displaced downwards. Plate XI. Fig. c illustrates a case of this rare variety of fracture through the lower segment of the glenoid cavity, with displacement downwards of the fragment. The patient was admitted to the Great Northern Central Hospital suffering from an injury to the shoulder, which was taken to be a dislocation of the head downwards. The skiagram shows the fracture and the typical displacement. A case recorded by Spence is the first authentic instance of this fracture. A patient who had fallen upon the shoulder whiLst in a state of intoxication was brought into the Edinburgh Royal Infirmary. The man died some days afterwards from meningitis. " The fracture was found to pass obliquely from below upwards and forwards, commencing about half an inch behind the origin of the long head of the triceps, and separating the neck and four-fifths of the lower part of the glenoid cavity from the scapula. The long head of the triceps and the whole of the glenoid ligament had also been torn from the upper fragment of the glenoid cavity, and carried along with the displaced portion." In fractures through the neck of the scapula, the coracoid process would necessarily follow the glenoid cavity, being detached along with it. Mobility of the coracoid would, therefore, be a valuable sign of this rare fracture. Fractures of the Humerus The fractures to which this bone is liable may be conveniently divided into three groups : (1) Those afiecting the upper extremity, or that part which is situated above the surgical neck. (2) Those of the shaft, and (3) Those of the lower articular extremity. Fractures at the Upper End of the Humerus. — (a) Of the anatomical neck, the so-called intracapsular fracture. This Fig. 134. — Fracture of lower end of Fig. 133. — Fracture of shaft of humerus humerus, with backward displacement and upper end of radius (shrapnel wound). of the lower fragment. 160 EADIOGKAPHY Fig. 135. — Fracture of .shaft of humerus lower fragment and elbow-joint. rotation of Fig. 136. — Fracture through external condyle with for- ward and upward displacement of the fragment of bone. The presence of chronic arthritic changes in the joint indicates that the injury is one of some standing. The radiograjih was taken many months after the primary injury. is always due to blows upon the shoulder, never to direct violence. It is evidenced by signs of a severe local trauma, with loss of mobility of the arm. The head of the humerus is found to be irregular in shape on examination from the axilla, and the fragment, if detached, may be felt. Crepitus is ob- tained on moving the arm, and therefis slight shortening. (6) Fracture through the surgical neck. This is a common injury. There may or may not be a considerable degree of displacement, or the lower point of the bone may be im- pacted into the upper ; the latter may be partially split. (c) The great tuberosity of the humerus is frequently de- tached and displaced. {d) The epiphysis of the head may be detached from the shaft, and there may be a considerable degree of displace- ment. Fracture of the Shaft of the Humerus.— This bone is frequently fractured, and the injury may occur at any part of its length. The most common injury is about the junction of the upper with the middle third. The displace- ment may be considerable. An unusual displacement is shown in Fig. 135, a trans- verse fracture with marked rotation of the elbow -joint inwards ; the lower fragment of the humerus is nearly at right angles to the upper. The head of the radius appears to have been injured. PLATE XII. — Fractures in Region of Elbow-joint. a, Vertical fracture of head of radius. b, Fracture through head of radius, displacement forwards of fragment. c, Fracture through lower end of humerus above epiphyseal line, displacement backwards. d, Fracture dislocation at elbow-joint. INJURIES IN REGION OF ELBOW-JOINT 101 Injuries in the Region of the Elbow-joint Fracture of the Lower End of the Humerus.— The humerus is frequently involved in injuries of the elbow-joint in adults and in children. It gives rise to a typical displacement, which is clearly revealed upon examination of the radiographs obtained. The displacement varies with the direction of the injury. The lower end, along with the elbow-joint, may be displaced backwards, while there may also be some lateral displace- ment and rotation. Stereoscopic radiographs are extremely useful in these cases. Fig. 138. — Fractures through shafts of radius and ulna. The position of both iDones is faulty. There is also a fracture through the lower end of the radius. Fig. 137. — Dislocation of elbow-joint. Separation of the Epiphysis of the lower end of the humerus is a common injury in this region. It is very difl&cult to show in children, and requires more careful examination than any other injury. Dislocations of the Elbow-joint are common, and frequently combined with fracture in the region. Fracture of the Olecranon may be complete or incomplete. It is commonly a transverse fracture, though it may be oblique or vertical, or the upper portion may be shattered. The displacement varies with the extent of the fracture. Fracture of the Coronoid is a rare injury. It is generally associated with a dislocation of the forearm backwards. When the fracture is reduced, the bones tend to slip out again readily. Fracture of the Head of the Radius is by no means an uncommon injury ; it may be complete or incomplete. 11 162 EADIOGRAPHY Fracture of the Shaft of the Radius and Ulna One or other of the bones may be broken. The usual seat of injury is near the middle of the shaft, in which case both bones are frequently broken, Autero-posterior. Lateral. Fig. 139. — Fracture of shaft of ulna (the result of a gunshot wound). and the displacement may be considerable. One or other bone may be involved in injuries at the elbow- joint or wrist- joint. Injuries at the Wrist-joint Fracture of the lower end of the radius and ulna is included in the description of the common Colles fracture. The results of the analysis of a large number of cases of fracture at the wrist- joint investigated by Dr. R. W. A. Salmond and the author may be quoted {Lancet, Nov. 2, 1912). (a) The Radius. — This shows injury in 93 per cent, of the total number of cases. The large percentage is without doubt due to the important part the lower end of this bone takes in the mechanism of the wrist-joint. Most injuries at the wrist are carried up from the hand and are transmitted through the radius^ hence the great frequency of damage to the lower end of the bone. The radius alone is injured in 41 per cent, of the total number of cases^ showing that, while PLATE XIII. — Fractures in Forearm, Wrist, and Hand. a, Fracture of terminal phalanx of tliunib, backward displacement. Lateral and antero -posterior views. b, Fracture of trapezium. c, Fracture through lower end of shaft of radius, very little displacement. d, Non-union fracture of radius and ulna, formation of false joints. PLATE XIV. — Fractdres at Wrist-joint. Fracture of lower end of radius, a, Lateral view showing displacement, b, Antero-posterior view showing nature of fracture. c, Antero-posterior view of separated epiphysis of lower end of radius, d, Lateral view to show displacement. e. Fracture through lower end of radius. /, Colles fracture, antero-posterior view. INJURIES AT THE WRLST- JOINT 103 it is injured in nearly every case'/ the injury is more often distributed to some of the other bones than confined to itself. The radius is injured along with the styloid process of tlie ulna in 12 per cent, of the total number of cases. The radius is damaged, together with the shaft and the styloid of the ulna, in 3 per cent, of cases. This is therefore infrequent, and the more so as the majority of the instances are due to a fracture carried up from the damaged styloid process into the shaft of the ulna. The frequency of injuries to the radius and the shaft of the ulna is also low — namely, 3 per cent. It will be noticed how much more frequently the radius is injured with the styloid of the ulna than with the shaft, and it is interesting to compare this with the corresponding injury in the un-united epiphyses series. Injury is confined to the radius and carpus in 4 per cent, of cases. Direction of Injury. — The great majority are transverse, 67 per cent. ; T- shaped in 16 per cent. ; fracture from the centre of the lower end across the styloid process, 8 per cent. ; V-shaped, 4 per cent. ; fracture of styloid process, 3 per cent. ; oblique, 2 per cent. ; longitudinal, 2 per cent. ; and injury at the inferior radio-ulnar articulation, about 1 per cent. Where the shafts of both fore- arm bones are injured the direction in the radius is transverse in all the cases examined. Position of Injury. — -By far the commonest is half an inch above the lower end of the bone. It is striking that 99 per cent, of the injuries recorded are three- quarters of an inch or less from the lower end. Displacement of Fragment. — This is backward in 74 per cent., forward in 2 per cent., and there is none in 24 per cent., but most of the cases examined had been manipulated by the surgeon, so displacement is more or less mislead- ing. Outward and inward rotation and displacements are not recorded, as many of the cases showed rotation, chiefly outwards, but it was often difficult to decide which to include and which not. (6) The Ulna. — Some part of this is injured in 49 per cent, of the total number of cases, about one-half the frequency of the radius. Injury to the styloid process occurs in 46 per cent, of the total number of cases, so that by far the commonest injury to this bone in this series is here. It is interesting to contrast the frequen- cies with which the styloid processes of the ulna and radius are damaged. In the former 46 per cent, and in the latter 3 per cent, show fracture of these processes, and we think the explanation is due partly to the styloid of the radius being structurally stronger than that of the ulna, partly because, the fragment of the radius being most commonly displaced backwards and rotated outwards, the internal lateral ligament attached to the apex of the ulnar styloid is put on the stretch, and must either rupture or exert tension on that process, while at the same time, with the fragment of the radius rotated outwards, the interarticular fibro-cartilage attached to the base of the ulnar styloid pulls on that base and helps to damage it. Direction of Injury. — There is no tendency towards any one type, nor is there any predominant type in this bone when the shafts of both forearm bones are damaged. That no tendency has been noted is perhaps because the injury is relatively rare and a sufficient number of cases has not been examined. Position of Injury. — All are within 2 inches of the lower end, and so, on the whole, extend further up the shaft than in the radius. As would be expected, the majority are at the styloid process, 94 per cent. Displacement of Fragment of the Shaft. — This is chiefly backwards, as in the radius, though, owing to a fracture in some cases being continued up from the styloid process, the frequency with no displacement is also high. 164 RADIOGEAPHY (c) The Carpal Bones. — Injury is present in one or more of these in 13 per cent, of the total number of cases. This proves how frequently these are damaged in wrist injuries, and probably the frequency is even greater, as only undoubted cases of injury are included. The carpus without either of the forearm bones is injured in 5 per cent, of cases, the carpus and radius in 4 per cent., and in none is the carpus injured with the ulna only, showing that the ulna does not directly take part in the mechanism of the wrist-joint. The carpus, radius, and ulna are together injured in 3 per cent, of cases. The scaphoid is the one most frequently damaged, no less than thirteen times out of nineteen. Next in order is the trapezium, while the carpal bones towards the ulnar side are less frequently involved. Fractures of the Bones of the Hand Fractupe of the Carpal Bones.— Any of these may be fractured, examples being met with in routine examination. Fractures of the Metacarpal Bones are common. Perhaps the most frequently met with is that of the base of the first metacarpal, Bennet's fracture. Plate XV., fig. d illustrates the nature of the fracture and the displacement commonly met with. Fractures of the Phalangres are also common. There may be no displacement in some fractures. The diagnosis can be made by a screen examination, but even with these small bones it is always well to confirm the diagnosis by taking a radiograph. A negative diagnosis should never be made on the screen examination alone. Fractures of the Pelvis The pelvis is often injured by direct or indirect violence. A radiograph should be taken of the whole pelvis in one picture, or several smaller ones may be taken to discover the nature of the injury. The iliac bones may be fractured, when it is sometimes difficult to show the seat of the lesion. When the sacrum is damaged, there may be a fracture at the sacro-iliac synchondrosis, and the body of the sacrum may also be involved in these injuries. The pelvis is often damaged when the violence is of a crushing type, or it may be broken by direct violence. The ischium may also participate in the injury. The coccyx is frequently fractured. In all doubtful cases both sides of the pelvis should be examined, and the hip-joints should also receive attention. The common injuries are easily distinguished, but there are many grades of fracture, where the injury may not be demonstrable if only one radiograph be taken. Injuries near the Hip-joint In some cases of injury at the hip-joint a widening of the interarticular space may indicate an effusion of blood into the joint, which later on may lead to inflammatory changes and abscess formation. Q 2 ^is FRACTURES OF THE FEMUR 165 An uncommon injury to the hip-joint has been recorded, where the head of the bone was driven through the acetabulum into the pelvic cavity. Or the acetabulum may be fractured to a lesser degree. This may be shown on examination. The Neck of the Femur is frequently broken when, especially in old people, there may be impaction. Traumatic coxa vara is a fairly common occurrence. Fracture through the Great Trochanter is also common. It may be localised to the trochanter or may extend downwards obliquely into the shaft. Fractures of the Femur Fracture throug'h the Shaft below the lesser trochanter is an injury often met with. Fractures of the Lower End. — (1) Transverse supra - condyloid fracture is practically identical with that involving the lower third of the femur. (2) T- or Y-shaped fracture of the condyles. In this a transverse frac- ture is complicated by a fissure which runs into the joint, separating the two condyles. (3) Separatio?i of either condyle always results from direct violence, the line of fracture being oblique. (4) The lower epiphysis of the femur is separated from the shaft in young people. (5) Longitudinal and spiral frac- tures running down to the knee- joint are met with in the femur. Fig. 140. — Fracture through shafts of both femora. The fracture is comminuted ou the left side. Fractures of the Patella These may vary from mere fissures to complete fracture with wide separation at the line of fracture. The partial fracture is the one which it is most important to recognise. A lateral view of the knee-joint is the most useful position in which to radiograph the joint for its recognition. Fractures of the Bones of the Leg The tibia and fibula may be involved when there is a fracture of the lower end of the femur ; they may be broken together or either bone by 166 KADIOGRAPHY itself. Fractures of the shaft of the tibia and fibula may vary from a fine crack to a marked degree of fracture, with displacement of the fragments. The tibia is frequently the seat of a spiral fracture. The fibula only may be fractured, when there is no marked displacement or external sign of fracture. Fractures in the Neighbourhood of the Ankle-joint These are usually produced by indirect violence. There may be marked displacement of the foot. Pott's Fracture. — The fibula is generally broken, three inches above the tip of the external malleolus, and the foot is displaced outwards. The internal malleolus may also be broken, with frac- ture of the lower end of the fibula, or it alone may be broken. Fracture of the Os Calcis is a comparatively common injury, the re- sult of direct violence. The degree of damage to the bone varies from a crack to a severe crushing of the bone. Fracture of the Astragalus. — The lesion is often a severe, ' com- minuted one . Both bones may be broken when a patient lands heavily on both feet ; and these fractures are often associated with fracture of other bones of the foot. Any of the tarsal bones may be fractured. The extent of the injury is often difficult to determine. It may be merely a crushing of the bone, in which case it is not easy to distinguish the injury from changes which are the result of disease, or there may be a distinct line of separation. The metatarsal bones are frequently involved in injuries to the foot. Fractures may be transverse or longitudinal. Fissured fracture of the bone is not uncommon. The phalanges are also frequently injured. Two positions of the foot should always be taken when looking for fractures. Stereoscopic pictures are very helpful in doubtful cases. Fig. 141. — Fracture of os calcis (gunshot wound). iL. PLATE XVI.— NoiiMAi. Hji', Dislocation, and Fracture at Hip-joint. a, Normal liip-joint, showing the head of the femur ; the acetabulum is seen surrounding part of the head. h, Dislocation at hip-joint, c, Fracture through neck of femur (intracapsular). PLATE XVIf. — Injuries and Disease of Pelvis and Hip-joint. a, Fracture of pelvis in a child ; the injury has occurred at both pubic bones, and on one side through the ischium. b, Fracture of neck of femur, impaction into great trochanter. c, Displacement of upper end of femur in a child. The acetabulum is eroded and the head of femur is absent. This is probably the result of tuberculosis. The appearances are similar to those of con- genital dislocation. DISEASES OF BONE All varieties of bone disease are met with in the radiographic examination of the bones, it being possible to trace the progress of disease from the slightest beginnings to the most advanced stages. A thorough appreciation of the normal appearance of bone is necessary before we can make out departures from it. Good negatives are essential, that is, the negative must show the finer detail as well as the outline of the bone. Soft tubes give better plates for this purpose than hard ones, but the exposures require to be longer, and this is in some cases a disadvantage, as movement on the part of the patient is apt to spoil the picture. When a long exposure is necessary the limb may be kept quite still by laying sand-bags around it and upon the parts not required in the picture, or soft pads may be placed on the limb, and a compression apparatus fixed lightly down upon them. The use of a cylindrical diaphragm seems to give sharper radiographs by cutting off the secondary radiations. When practicable it is better to place the X-ray tube as far away from the plate as possible, a distance of three feet (or more) giving the parts with less distortion. When a particular bone has to be examined it is a good plan to get the corresponding one on the healthy side for comparison, taking care that both bones are radiographed under the same conditions of tube and distance. A brief consideration of the pathology of bone is necessary in order to understand clearly the various conditions met with in the course of examina- tion of bone disease. Many different terms are applied more or less loosely to the pathological processes, and much confusion is introduced thereby. Necrosis. — Necrosis or death of bone may occur in a variety of forms, and from many different causes : (1) Acute localised suppurative periostitis, the sequestrum or dead mass being then simply a superficial plate or flake of the compact interior. (2) Acute infective osteomyelitis, the sequestrum then often involving the whole thickness of the bone, and invading more or less of the diaphysis. (3) Acute septic osteomyelitis, usually traumatic in origin, the seques- trum being annular in shape, and involving more of the interior of the bone than the exterior. (4) Acute or subacute septic osteitis of cancellous bone, the sequestrum consisting of small spiculated fragments of the bony cancelli which have escaped absorption by the granulation tissue which always forms in such a process. 167 168 EADIOGEAPHY (5) Tuberculous disease of cancellous tissue, the sequestrum being light and porous, often infiltrated with curdy material, and rarely separated completely from the surrounding parts. (6) Syphilitic disease of cancellous or compact bone, usually resulting from excessive sclerosis, or gummatous disease of the periosteum, which has become septic. (7) The action of local irritants, e.g. mercury and phosphorus. Caries. — (1) Osteoporosis, or rarefaction of bone, a clinical condition resulting from inflammation, and consisting of a soft and spongy condition of the bone. (2) Caries sicca, when the process occurs without suppuration. (3) Caries suppurativa, when pus is always present. (4) Caries fungosa, when granulation tissue is always in excess, especi- ally in tuberculous disease of the articular ends of bones. (5) Caries necrotica. — Necrosis is associated with caries, the sequestra consisting of spiculated fragments, or in tuberculous disease of larger masses. Sclerosis of Bone is usually the result of some chronic inflammatory infection : (a) Chronic periostitis, whether simple or syphilitic. (6) Chronic osteomyelitis, simple, tuberculous, or syphilitic. (c) Chronic osteitis of the compact bone, which is always secondary to a case of the former. Classification of Inflammatory Affections of Bone (1) Periostitis. — (a) Acute localised, with or without suppuration. (6) Acute diffuse, always associated with, or secondary to, acute in- fective osteomyelitis. (c) Chronic simple, or hyperplastic. {d) Chronic tuberculous, (e) Chronic syphilitic. (2) Osteitis of Compact Bone, which is always associated with, and secondary to, either periostitis or osteomyelitis, and so will not be described separately. The acute form results in necrosis, the subacute in osteoporosis, and the chronic in sclerosis, except in tuberculous disease. (3) Osteomyelitis, or inflammation of the medulla of long bones, (a) Acute septic (traumatic). (6) Acute infective (idiopathic), acute panostitis. (c) Subacute simple or infective, e.g. after fractures, or during the separation of sequestra, resulting primarily in rarefaction, but finally in sclerosis. {d) Chronic simple, tuberculous or syphilitic, usually causing general enlargement and sclerosis of the bone, even if locally some rarefaction is present. (4) Osteitis of the Cancellous Tissue may similarly be : (a) Acute septic, or traumatic. cS to 3 cS D > X So t w " o Ph o S 5 =3 2 sB 5 '^ r2 3 ■" o 3 o =^ op D ^ =c-s s:3 .2 go 33 &p_o " PLATE XX.— Fractures at the Ankle-joint. a. Oblique fracture through lower end of fibula, (a) Lateral, {b) Antero-posterior views. b, Fracture of internal and external malleoli, displacement of foot outwards at ankle-joint. c, Fracture of astragalus. d, Fracture dislocation at ankle-joint. e. Fracture lower end of fibula. PLA.TE XXI. — Fractokes of Leg, Ankle, and Foot. «, Oblique fracture of shaft of tibia, lateral view, shows epiphj'ses of lower end of tibia and also of OS calcis. b, Antero-posterior view of tibia and fibula, showing an oblique fracture of shaft of tibia ; and also epiphyses at lower end of tibia and fibula. c, Fracture through shaft of femur ; the bone is rai'efied and is probably the seat of secondary carcinoma. d, Fracture of lower end of tibia and fibula, forward dislocation of tibia. e, Fractures of tibia and fibula. /; Fractui'e of base of second and third metatarsal bone. DISEASES OF BONE 169 (6) Acute infective. (c) Subacute simple or septic. (d) Chronic simple, syphilitic, or tuberculous. When limited to the articular end of a bone in a young person, this is sometimes termed epiphysitis. Acute Localised Periostitis is usually the result of traumatism. It may end in an inflammatory swelling of the surface of the bone, which later may cause a superficial abscess. A thickening of the soft parts over the bone may be shown. Resolution may follow this, and a localised thickening at the seat of inflammation may remain for some time. If suppuration occurs and pus forms, it maybe possible to demonstrate its presence radiographically. Superficial Necrosis. — This is characterised by the separation of small particles of dead bone. New bone may be thrown out around the inflamed area, and leave evidence in the form of layers of more or less dense bone. Acute Infective Osteomyelitis. — Acute necrosis occurs generally in children of low vitality, often of tubercular inheritance. The early manifesta- tions of this disease are often extremely slight. A hardly perceptible in- flammatory process in the neighbourhood of the epiphyseal line or near a joint rapidly spreads, involving the whole diaphysis of the bone. A sub- periosteal abscess may form, while the central portion of the bone escapes almost entirely. Should the process commence in the vicinity of the epi- physeal line it may spread in several directions, may involve the medullary cavity, and give rise to the most typical form of osteomyelitis. Necrosis follows, usually implicating the whole thickness of the medullary cavity and diaphysis, and sometimes extending its whole length. Occasionally the neighbouring joint becomes involved. The pictures presented by this disease show all stages, from a preliminary inflammatory process, to advanced necrosis, formation of sequestra, and new bone formation. If radiographs are taken at regular intervals, the whole process of inflammation, suppuration, necrosis of bone, sequestra formation, deposit of new bone around the dead bone, and the gradual building up of new bone after operation to remove the sequestra may be followed up. The pathology of this form of disease of bone may be watched by means of radiography. The demonstration of the presence of free bone in a cavity surrounded by new bone is a guide to the surgeon in the operation as to when and where to operate, and indicates clearly the progress the bone is making in the direction of recovery. Acute Septic Osteomyelitis. — This arises as a result of infection from without, in cases of compound fracture, and after amputation or excision of bone ; the shafts of long bones are affected, and the disease generally runs a rapid course. Typhoid Osteitis. — The typhoid bacillus may lie dormant for years without causing any abscess formation. The appearance is typical, and is shown in Fig. 142. Chronic Inflammation of Bone. — Chronic osteo - periostitis, a chronic inflammatory process, results in overgrowth, thickening, and con- 170 RADIOGRAPHY densation, (1) as a localised chronic periostitis, traumatic, rheumatic, or syphilitic in origin ; or (2) as a diffuse form, usually tubercular or syphilitic, which tends to involve the whole bone. It may result in a small abscess or central necrosis. Around this focus the bone becomes thick and indented. Examples of this are shown in Plate XXII., figs, d and e. Fro. 142. — Typhoid osteitis and periostitis resulting in an abscess. Fig. 143. — Elbow-joint showing disease. Formation of new bone along shaft of iilna and humerus. Chronic osteitis and periostitis, probably tuber- culous iu origin. Tuberculous Disease of Bone. — This form of disease of bone is frequently met with in X-ray examinations. Bones may be affected in two ways by tuberculosis. The periosteum or the cancellous tissue may be primarily involved. Tuberculous Periostitis, or specific inflammation of the periosteum,, is met with. Caseation and suppuration are likely to follow, frequently leading to the formation of abscesses, and, later, of discharging sinuses. The inflammation may result in a thickening of the layers of bone and a shutting in of the products of suppuration, hence, if situated near a joint, the pus may burrow under the dense bone and invade the joint. Tuberculous Osteitis always arises in cancellous tissue, and it affects the short bones or the shafts or ends of the long bones. The short bones of the hands and feet are liable to this condition, especially in children. When the phalanges are involved the condition is known as tuberculous dactylitis. The typical appearance of this condition is shown in Plate XXVII., fig. c. Several bones may be simultaneously affected. Some slight injury may determine the onset of tuberculous periostitis or osteitis. Tuberculous Epiphysitis. — An inflammation affecting primarily the epiphyseal line and adjacent bone. The tendency is for it to spread and involve the joints by the invasion of the synovial membranes. Separation of the epiphysis may result. The adjacent bones show a condition of osteitis and o '3 > s « ^ H o -t: g o o S ^ o a "o '"' ^ to CO +^ 03 > •So ^3 <| c3 g a H SYPHILITIC DISEASES OF BONE 171 periostitis. Abscess of bone, more common in adults than in cliildren, may- result. Chronic abscess in the head of the tibia is somewhat frequent. The characteristic symptom of deep aching pain calls attention to the possibility of bone abscess. The bone around the abscess cavity is frequently very dense, though it varies in this respect in parts of its circumference. Radio- graphically, the condition may be recognised by an increase in shading and loss of detail in the bone structure on the surface. The periosteal outline is blurred, and may show patches of caries or collections of pus. The soft parts are frequently involved in the inflammatory process, and a soft puffy swelling may be seen over the affected portion of bone. When the disease has advanced, the original focus of disease shows up as a lighter area, with patches of rarefaction of bone leading from it. The fine detail of the bone is lost, and a general haziness is left in its place. Later, when pus has formed, an irregular abscess cavity can be seen, there being as a rule very little con- densation of bone round the abscess. Should the cancellous tissue in the neighbourhood of an epiphyseal line be involved, the disease extends through the line, and affects the epiphysis, which shows as a spongy rarefaction with irregular edges. The inflammatory process spreads into the joint itself, and sets up a synovitis, which is characterised by a general distension of the joint and an obscuring of detail. Syphilitic Diseases of Bone. — The osseous tissue may be involved in acquired syphilis in either the secondary or tertiary form. Syphilis of the bone is frequently met with, and it is often difficult to differentiate it from a simple inflammatory process. Chronic thickenings in the form of nodes are diagnostic of syphilis. When a considerable extent of bone is involved, it may be difficult to distinguish between this condition and an early stage of malignant disease. In the latter the disease spreads more rapidly, and the characteristic appearances of malignancy manifest themselves. In the tertiary period the bones may participate in the changes which involve any and every tissue of the body. These consist of an infiltration and overgrowth of the connective tissue, which, if diffused through the organs, produce scler- osis, or, if localised to one spot, lead to the formation of a gumma. The subperiosteal gumma may be met with. It probably results from caries of the adjacent bone, and if it extends widely an extensive area of bone may become eroded and irregular. The skull is the part most frequently involved in these changes, and may show a curious worm-eaten appearance. The formation of gummata, several of which may break down, gives a curiously uneven appear- ance to the radiograph of the skull, thickening and enlargement, alternating with broken-down tissue, leading to marked thinning of the bone in places. Congenital Syphilis. — Nodes, known as Parrot's nodes, form on or around the anterior fontanelle. The newly formed bony tissue becomes sclerosed and dense, and deformity may then persist through life. A similar condition is met with in the shafts of the long bones, due to the alternating deposition of lamellae of soft and hard bone outside the ordinary compact bone. Syphilitic Epiphysitis. — This condition is characterised by enlargement 172 EADIOGEAPHY of the ends of the bones. It is met with in infants, and somewhat resembles rickets, but comes on at an earlier date. The enlargement is situated mainly in the epiphyses, but not uncommonly extends some way along the shaft, thus contrasting forcibly with rickets. The change commences at the zone of calcified cartilage nearest the diaphysis, which becomes friable, thick, and irregular, and may become transformed into granulation tissue as the disease progresses. Later, reparation of the epiphysis may follow. The disease is usually symmetrical and often multiple. A symmetrical overgrowth of the tibia, combined with an anterior curvature, often occurs in syphilitic children, resulting in permanent deformity of the legs. Craniotahes. — A condition characterised by localised absorption of the osseous tissue of the cranium, leaving small areas where the bone is thinned or absent. Radiographically, these are often met with. Rickets. — The chief changes are found in the neighbourhood of the epiphyses ; the epiphyseal car- tilage is enlarged, thickened, and irregular ; there is an increase in the cartilaginous elements of the ., bone, and a delayed ossification ; ,i> * , the bones are weaker and less A 1> * rigid, and become deformed m ^^ \- \ ' . consequence. The ossifying pro- cess is delayed. Changes in the shape of the bones of the head may be detected, and the spine may be affected by kyphosis ; the teeth do not erupt till late, and are stunted. Changes in the ribs are produced by en- largement of the costochondrial junctions (beaded ribs), which when present on both sides of the sternum produce what is known as the rickety rosary. The principal changes met with Fig. 144.— Wrist and hand of child, showing changes radiographically are at the in lower end of radius and ulna due to rickets. • ^ it p ,i t epiphyseal lines of the long bones and the adjacent joint. Aehrondroplasia. — A curious congenital condition, resembling rickets, in which the growth of the osseous tissue on the shaft side of epiphysis of the long bones of the arm and of the leg is affected, so that the limbs are short and stunted, and the stature correspondingly diminished, although the epiphyses are normal. Simple Atrophy of Bone.— This results from a variety of conditions, quite independent of rarefying inflammation, in which it is a marked feature. It may be congenital, or may be due to : PLATE XXIV. — Tubercular Disease of the Hip-joint. a, Tubercular disease of hip-joint affecting chiefly the upper part of acetabulum. h. Tubercular disease of hip, absorption of head and greater part of neck, upward displacement of femur. (Radiograph by Dr. Salmond. ) c, Later stage of tubercular disease of hip-joint, disorganisation and displacement of head, large abscess on outer side of shaft of femur. CONDITIONS PREDISPOSING TO FRACTURE 173 (a) Interference with the' epiphysis, as in rickets, or injuries, or as a sequence to tuberculosis or other inflammation, involving the function of the cartilage. (6) Injury or disease of the nervous system or of peripheral nerves, as tabes dorsalis, syringomyelia, leprosy, etc. (c) Want of use as in a paralysed or ankylosed limb. (d) Local pressure, as of a tumour growing within or outside the bone. (e) A senile change. These conditions are illustrated in many of the skiagrams showing disease of bone and joints, and attention is called to them as they occur. MoUites Ossium or Osteomalacia. — A condition characterised by the absorption of the osseous substance of the bones, as a result of which softening and rarefaction are produced, followed by bending or spontaneous fracture. Pathologically there is a replacement of the medullary substance by a soft, fibro-cellular tissue, which is exceedingly vascular, and into which haemor- rhage may occur. Attention may be called to this condition when a spon- taneous fracture, or fracture from slight violence occurs. The changes in the bone can be shown radiographically. Morbid Conditions of Bone which predispose to Fracture.— It is important to bear well in mind several conditions of bone which predispose to fracture. When fracture from slight violence occurs, suspicion should at once be aroused, and the examination should be conducted on lines which will enable the radiographer to show not only the fracture, but also the con- dition which has predisposed to it. For this, good negatives are essential. A picture which will show a fracture is often not full of fine detail, without which no opinion on bone disease can be formed. In the same way a screen exam.ination will show a fracture, but an opinion of the bone condition can- not be formed from it. The most usual conditions predisposing to fracture are : (1) Atrophy of bone. This may be senile, or due to disease, e.g. anky- losis of a joint or certain nervous afiections. (2) Fragilitas ossium. This consists in an inherited tendency to spon- taneous fracture, occurring in children and adults. (3) Bone disease, such as tuberculosis, rickets, syphilis, osteo-malacia. (4) Local bone disease or tumours, such as sarcoma, secondary car- cinoma. A condition which frequently leads to fracture is a cystic condition of bone. Many examples have been shown of late years occurring in the long bones, the humerus being a common seat of this tumour. It is frequently a very slow form of myeloid sarcoma. Elmslie has drawn attention to this cystic disease of bone, and shown several interesting examples. DISEASES OF JOINTS These are numerous, and have characteristics which may often be shown by radiography. A great deal of light has been thrown upon the differential diagnosis of such conditions as tuberculosis of joints, chronic arthritis, gout, and other diseases by the systematic examination of joints at regular in- tervals during the progress of the disease. The various forms of arthritis may be distinguished one from the other. Acute inflammation of a joint may be shown when the synovial sac is seen fully distended ; later the shadows caused by the fluid will become denser when pus forms. The changes in cartilage, especially when the disease is chronic, are seen, and later the bone becomes affected. Radiographically the interspaces between the cartilages are increased when the joint is full of fluid. The opposite limb should also be taken in order to determine departures from the normal. Tuberculous Disease of Joints In this disease the departures from the normal are marked. The synovial membrane is swollen and pulpy. The joint is very much enlarged, this being shown when the joint is radiographed, variations in the density of the shadows of the soft parts indicating an inflammatory change in the synovial membrane. The cartilage becomes eroded, and later the process extends to the bone itself, which may be shown to be eroded. In places irregular thickenings of the bone also occur, and the bone in the vicinity of a joint may be thickened for some distance up the shaft. In the later stages the joint shows marked disintegration, with a synovial cavity filled with caseous material, this showing in the radiograph as faintly marked irregular shading within a greatly swollen joint. The surrounding bones, especially those below the joint, show atrophic changes. All the bones entering into the joint become affected. All stages in the history of tuberculous disease of joints may be demonstrated by radio- graphy. The very early stages are, however, the most difficult on which to give an opinion, and clinical evidence should always be taken into account when an opinion is required. It is of the utmost importance to be able to determine the presence of early tuberculosis, for on that the future treatment depends. In joints which have been the seat of recent injury, changes due to the injury may be detected, and these may later become the centre of a tuberculous infection. Consequently, when examining joints after injury it is important to be able to distinguish fine changes in the parts. 174 PLATE XXV. — Tubercular Diseases of Joints. a. Tubercular disease of lower end of femur, involving diaphysis and epiphysis, a considerable degree ot sclerosis of bone around an abscess cavity. h, Lateral view showing the same changes. (Radiographs by Dr. R. W. A. Salmond. ) c. Tubercular area in scaphoid. (Radiograph by Dr. R. W. A. Salmond.) d, Tubercular disease at ankle-joint ; note rarefaction of bones of foot. PLATE XXVI. — Tuberculosis of Bones and Joints. a, Tubercular disease of bones of hand, characterised by new bone formation affecting metacarpal bones and phalanges. h, Tubercular disease at end of radius, localised abscess. (Radiograph by Dr. R. W. A. Salmond. ) c, Tubercular dactylitis affecting 2nd and 3rd metacarpal bones. d, Tubercular disease at upper end of humerus (caries sicca). (Radiograph by Dr. R. W. A. Salmond.) TUBERCULOSIS OF JOINTS 175 The later stages of tubercular disease are much easier to recognise ; rarefaction, caseation, and formation of pus are readily distinguished. A localised rarefaction of bone in the neighbourhood of a joint should arouse suspicion of the presence of pus, particularly when the bone round the rarefied area shows a tendency to condensation. The epiphysis may assume a worm- eaten appearance, which is distinctive of early caries ; later this may completely disappear. It is important also to be able to distinguish between tuberculous and non-tuberculous disease of bone. In acute and subacute osteomyelitis Fig. 145. — Tuberculosis of left hip-joint, particularly atfecting the acetabuluni. Note the diiferencie between the two joints and relative shortening of neck on attected side. afiecting the neighbourhood of a joint, and particularly in the latter, the tendency is towards the formation of new bone, and the destructive process is not then so manifest. Irregular thickening of the periosteum with the deposition of new bone favours a diagnosis of non-tubercular disease. In some cases a degree of caries sicca preponderates iii the process, and then there is not the same tendency to the formation of an abscess. The bone shows rarefaction for a considerable distance up the shaft. An accompanying degree of rarefaction of the bones entering into the joint results from the restriction of movement, and need not necessarily be taken as an indication of the extent of the disease. Ankylosis of the joint may follow the healing 176 RADIOGRAPHY of the inflammatory process. Displacements of the bones may result from destruction of the ends, in the hip-joint this being frequently shown as a dislocation upwards. Tuberculosis may be met with in practically any of the joints of the body, those most frequently affected being the hip, the knee, the elbow, the wrist, the ankle, and the shoulder. The appearances are characteristic. The spine is frequently the seat of a tuberculous caries which ends in abscess formation. In many instances the presence of an abscess can readily be Fig. 146. — Arthritis following injury of knee-joint. Lateral view. There is a breach in the continuity of the articular surface of the femur. The articular surface of the patella shows slight irregularity. The interarticular space between the femur, head of the tibia, and the patellar ligament is occupied by chronic inflammatory products indicated by a mottled appearance on the print. There is a sesamoid bone in a tendon on the posterior aspect of the joint. This print shows well the structure of the bones entering into the knee-joint, and the soft parts are very well shown. This quality of negative should always be obtained, if possible, when examining joints for it gives a good definition in all the parts. shown on radiographic examination. In a later stage a considerable degree of deformity occurs. These are more easily shown. The early stages of a tuberculous inflammation of bone, particularly when the spine is affected, is difficult to distinguish from a tumour involving the spine. A consideration of the history, temperature chart, etc., will help. The tumour shadow is usually more irregular, and generally involves the circumference of the bone, while an abscess may be more localised at one part. In doubtful cases an exploratory operation is to be recommended. Simple inflammatory changes in a joint are commonly the result of traumatism. An acute attack quickly subsides and recovery takes place, but it must be borne in mind that a simple injury may end in chronic inflammation, which may later become the seat of tuber- PLATE XXVII. — Chronic Arthritic Changes at the Knee-joint. a. Rheumatoid changes in knee-joint, with large bony deposit in front of femur. h, Chronic rheumatoid changes in knee-joint ; loose bodies have formed inside the synovial membrane. c, Knee-joint, showing extensive changes in patella, probably the result of traumatism. L008E BODIES IN JOINTS 177 culous invasion. In joints traumatism may lead to minute changes in bone and cartilage which, though not definite enough to be recognised as actual fractures, may yet be quite as serious in their after effects. Ligaments may be torn ; this may occur in the knee-joint, when the crucial ligaments are torn. There may even be a fracture of the spine or the tibia. These minute changes should be carefully looked for in all cases of joint injury. Atrophy of Bone may be found in the region of a joint, the result of disease following upon tuberculosis or other inflammatory process. Chronic Articular Rheumatism This affects several of the large joints, especially the knee and shoulder. The hip- joint is also affected. Eadiographically, the joints may present very little change and show practically no rarefaction. In very chronic cases there may be some irregularity of outline of the articular surfaces, indicating partial absorption of the cartilage. Chronic Articular Gout The radiographic appearance of the joints may not show much change, except that the articular surfaces may be unusually close together, and lack the rounded appearance they possess when covered with sound cartilage. Deposits of uric acid are occasionally clearly seen in the radiograph, forming a mass denser than the soft parts but not nearly so dense as the bone itself. Fringes of the sjmovial membrane may become detached and form loose bodies in the joint. Loose Bodies in Joints These are occasionally met with. The following description, which, gives the most usual varieties, will be found useful when a consideration of these bodies is called for : 1. Synovial fringes in which proliferation of cartilage cells has occurred, leading to the formation of a nodular mass, which is at first pedunculated, and is then cast off into the cavity of the joint by rupture of the pedicle. These bodies are usually composed mainly of hyaline cartilage, with bony material in the centre of the larger ones. They may become ossified through- out. They vary in size from about J-inch diameter up to 1 inch ; the larger ones are usually longer than they are broad. There may be only one loose body in the joint, or there may be several hundreds. It is not uncommon to find one body quite loose, and one or more still attached to the synovial membrane of the same joint. 2. Osteophytic outgrowths from the edge of the articular cartilage may become detached, and so form a loose body in the joint. These bodies are irregular in shape, and usually consist of a layer of cartilage covering an osseous centre. 12 178 EADIOGRAPHY Varieties 1 and 2 usually occur in cases of osteoarthritis. 3. A portion of articular cartilage with a thin layer of bone may become separated from the femoral condyle, and form a loose body in the joint cavity. This occurs probably as a result of injury. 4. A blood-clot in the joint may become gradually smaller and firmer, and so form a loose body. This occurs as a result of injury. 5. A portion of the synovial membrane may become thickened and indurated as a result of injury. This is nipped by the articular surfaces during the movements of the joint, and finally, as a result of the rupture of the pedicle, the body becomes loose. 6. In tuberculous disease of a joint one or several loose bodies may be found. These are composed of tuberculous material in the thickened synovial membrane. 7. Around a foreign body, such as the end of a needle, fibrous tissue may be formed. This and the preceding type of loose body are rare. 8. Partial detachment of a semilunar cartilage gives rise to a body which hangs into the joint. As this is usually still attached to the bone it cannot be said that it is a true loose body. It, however, gives rise to symptoms of a loose body in the joint. 9. An innocent tumour, such as a Hpoma, may form in the synovial membrane, become pedunculated, and so hang into the joint cavity. This is very rare. 10. A foreign body, such as a nail, bullet, or needle, may in rare instances form a variety of loose body in the joint. These, however, are usually spoken of as " foreign " bodies. Rheumatoid Arthritis or Rheumatic Gout This is characterised by marked deformity in a typical case. Eadio- graphically, the articular ends of the bones present the normal degree of translucency, or they may be more translucent, but there are irregular, knob-like projections, some of which appear more transparent. The joints may become ankylosed, and there is then continuous bony structure right through the joint. Hypertrophic Arthritis or Osteoarthritis This is a condition described separately, but it is probably a variety of the preceding types, characterised by a tendency to the formation of new tissue between bone and articular cartilage, which becomes calcified. There may be marked disorganisation of the bones. Charcot's Joints This is characterised by marked enlargement of the joint. The car- tilages are eroded, and osseous deposits occur in the ligaments, with irregular outgrowths of bone around the joint. PLATE XXVIII. — Diseases and Curvature of the Spine. a, Caries of cervical vertebrae, lateral view. 6, Curvature of upper dorsal spine (scoliosis). Curvature of spine, involving lower dorsal and lumbar vertebrae. d, Caries of lumbar vertebrae and sacrum. DIFFERENTIAL X-RAY DIAGNOSIS IN DISEASES OF BONES AND JOINTS It is important to be able to suggest, if only tentatively, a differential diagnosis in morbid conditions of bone, and, when the disease is near a joint, also of the condition of the joint. The tumours of bone most likely to com- plicate a diagnosis are (1) sarcoma, (2) cancer. The latter is generally accompanied by a primary lesion elsewhere, but the former frequently arises primarily in the periosteum (periosteal sarcoma) or in the substance of the bone (endosteal sarcoma). It is necessary to consider the appearances presented by tumours of bone when dealing with what appears to be an inflammatory condition. The subject will be dealt with more fully later. Tumour of bone may be complicated by superadded inflammatory changes which lead to still greater difE.culties in diagnosis. Sarcoma usually attacks the shaft of the bone, and produces changes similar to those caused by certain degrees of osteomyelitis, diflering, however, in that the latter show a more pronounced degree of periosteal reaction, as indicated by the deposition of new bone and the tendency to formation of sequestra. In medullary sarcoma certain areas of increased density appear which resemble spiculee or islands of osseous material, and show actual absorption of the bone, with very few or no normal portions of bone remaining about this point. In osteomyelitis, in addition to the more definite thickening of the periosteal shadow, there is a more definite formation of new bone about the necrosed area. Appearance of Joints in Tuberculosis When examining joints for evidence of tuberculosis the following symptoms should be looked for. They are met with in the course of many examinations of these cases. The earliest changes are naturally the most difficult to recognise. (1) Marked porosity of the bones forming the affected joint. (2) Actual loss of substance in the head, e.g. of the femur. (3) Actual loss of substance in the hollow bone, e.g. the acetabulum. (4) Extreme atrophy of the shaft of the bone. (5) Abscess formation, characterised by an increase of the normal 179 180 KADIOGKAPHY shadow of soft parts around the joint, accentuation and bulging of the joint outline. (6) Necrosis of portions of the bones, with formation of sequestra. (7) Arrested development of epiphysis, and changes at epiphyseal line. (8) Displacement of bones, particularly at hip-joint. Where the head or neck of the femur is displaced upwards this indicates that there is a marked change in the acetabulum. (9) Ankylosis of the bones forming the joint. Tubercular Dactylitis This is characterised by enlargement of the affected bones, deformity, and destruction of bone tissue. Enlargement of the bone is often accom- panied by rearrangement of the structure of the bone. Variations in density give the appearance of cysts in bone, the bone surrounding a rarefied area becoming sclerosed in parts ; hence the cystic appearance. Syphilis of Bone (1) Periosteal proliferation leads to considerable thickening, irregular in character. (2) Areas of increased rarefaction due to marked absorption of the lime salts, with an effort towards new bone formation. (3) Periostitis leads to many layers of new bone being laid down along the whole length of the bone. Generally multiple, it therefore affects many of the long bones. In other cases the thickening may be localised, causing areas of dense new bone formation. Syphilitic Dactylitis This is characterised by periosteal overgrowth, with little or no apparent disturbance of the bone, the appearance presented by this condition afford- ing a fairly reliable diagnostic point in favour of syphilis. Chronic infective Osteomyelitis (1) General infiltration causes a deeper shadow about the bone and joint when the disease appears in the vicinity of the latter. (2) Periosteal infiltration and overgrowth lead to marked increase of the adjacent bone, and this sclerosed bone appears to be much denser than normal bone, and the shadow is greatly increased in area. S Iz; hI a w ^ ^^ XI ^ - ?r1 ><^ fl^'^l w 5 o H "o !l; s , O X fl ■""S o =t? 5,r^ O r-; o .& bD "&I O) ^ O •--• r^ » ^ bo gT C .2 03 '? c3 OSTEOMYELITIS 181 Acute Osteomyelitis The earliest X-ray appearance of an osteomyelitis, which may run through all the stages of the disease in a few weeks, may be an area of rare- faction at the epiphyseal line, commencing in the diaphysis, and later in some cases extending into and involving the epiphysis. This ls followed by periosteal thickening, necrosis of bone, evidenced by areas of varying density, indicating sequestra. The disease may become localised, when radiographic- ally it is shown by an area of lighter shading surrounded by a periphery of denser bone. The condition may arise near the epiphyseal line. Abscess of bone may be the result of the inflammatory process, a typical instance being the well-lmown abscess in the upper end of the tibia or lower end of the femur. In the hip-joint a mixed infective process may give rise to appearances which have to be differentiated from tuberculous cases. Though the appear- ances may indicate a preponderance of evidence in favour of one or other of these diseases, it is not always possible to distinguish between them. A condi- tion where there is a tendency to proliferation of periosteum, thickening of bone and osteophytic outgrowth is more in favour of a non-tuberculous condition. It must not be overlooked, however, that a condition which commenced as a tuberculous one may become the seat of a mixed infection or vice versa. An infective area of inflammation may become the seat of a subsequent tuber- culous lesion. Marked evidence of bone disease in the vicinity of, but not involving, a joint, is rather an indication for a diagnosis of a non-tuberculous origin for the disease. A typical case may occur in the upper end of the femur, when an area of lessened shadow {i.e. a condition which allows of the readier passage of the rays through the bone substance) is due to a destructive process in the bone, with absorption of the bony salts. This is accompanied by a greatly thickened periosteum. The bone, therefore, appears on examination to be denser in the surrounding areas, in contradistinction to the general rarefaction which is so frequently seen in chronic cases of tuberculosis. The typical X-ray picture of a case of chronic osteomyelitis in an advanced condition, when the whole of the shaft of a bone has become involved, shows : (1) Areas of suppuration indicated by patches of varying density, rare- faction of bone, and small collections of debris and pus. (2) Newly formed periosteal bone, shown by the deposition of successive layers of bone outside the shadows of the original bone or what remains of it. (3) Necrosis of the cortical bone, indicated by irregular patches of denser shadow, with a well-defined periphery, beyond this being lighter shadows, where the living bone still remains. Generally these conditions are confined to the shaft of the bone involved, the epiphyses and joints escaping. The earliest X-ray manifestation is shown by a slight increase in the periosteal shadow at one or more spots, a definite swelling of the soft parts, and possibly abscess formation. 182 EADIOGRAPHY Acute infective Periostitis The diagnosis by X-rays of an early infection of the periosteum is attained by noting changes, such as thickening and bulging of the periosteum. The outline of the periosteum in normal bone is sharply defined, while in acute inflammatory conditions there is a general haziness of its outline in the affected part, or it may be broken and irregular, exposing the cortex of the bone. The formation of an abscess is shown by an increased depth of shadow in the neighbouring soft parts. In less acute cases this swelling may be due to inflammatory changes commencing in the periosteum. Tumours of Bone The simple forms of tumour are often diagnosed with ease, but the malignant tumours are frequently the subject of great doubt, both clinically and radiographically. The latter method of examination is often called upon, to decide, if possible, the nature of a doubtful swelling. In all such cases great care must be exercised, and all methods of examination should be employed. To make a positive diagnosis on the radiographic appearance alone is often misleading. The most malignant type of sarcoma, for instance, is, in the early stages at least, indistinguish- able from a simple in- flammatory process. Later, more decided features may be made out, but it must be insisted upon that radiographically it is often impossible to decide. The clinical history, the radio- graphic evidence, and in most of the early cases, at least, a fresh radiograph of the section at the time of operation should all be employed. The latter method puts the nature of the case beyond all doubt, and decides at once the extent of the operation. The clinical and radiographical features of cases of tumour will be dealt Pig. 147. — Sarcoma of lower end of femur. The bone has been sawu longitudinally in order to show the tumour in its interior. The appearance of this tumour in the amputated limb and in the living subject are shown in Plate XXX., Figs, c, e, and/. PLATE XXX.— Tumours of Bone. a, Periosteal sarcoma of shaft of humerus. Plate XXXII fig. a, shows recurrence in lung two years after amputation of arm. h, Myeloid sarcoma of shaft of humerus confirmed by microscopic examination. There have been several fractures at the seat of growth. c, Sarcomaof lower end of femur (after removal), d, Sarcoma of head of fibula. (Eadiograph by Dr. Reid.) e, Lateral view of c, from living subject. ^, Antero-posterior view of c. TUMOURS OF BONE 183 with later, but, in passing, -it may be observed that a knowledge of the macroscopic and microscopic appearances of tumours will aid the radio- grapher to grasp points in the progress of a case, which will often help to decide his opinion in a particular instance. Sarcoma is the most important primary tumour of bone, and almost any form of this may occur. Endosteal, or central, sarcoma generally com- mences in the medullary cavity or cancellous tissue, and results in the so- called " expansion " of bone, which consists of an absorption of bone from within, whilst at the same time new osseous tissue is being deposited from the Fig. 148. -Choudro-sarcoma of lower end of tibia. under surface of the periosteum. Fig. 149.— Sarcoma at upper end of humerus. This rrii T 1 • -ii is a form of periosteal sarcoma which rapidly The radiographic appearances will involved the soft parts. Radiographically, the correspond with the pathological humerus showed very faint irregularity at the -, T^ . J- , 1 T. periphery with thickening of the bone. changes. Expansion of the bone ^ with debris in the centre or sarcomatous new tissue, will be shown in the plate. The new bone forming from the periosteum is de- posited in more or less definite layers. When considerable expansion of bone occurs, it can readily be distinguished from inflammatory change processes, or cysts of bone, by the somewhat sharp nature of the expansion. The shaft above and below the growth is normal, and suddenly expands at the site of the tumour. The growth usually com- mences at the end of a long bone. It seldom encroaches on the articular cartilage, so that the joint escapes, although it may be distended with fluid. Dr. Emery, of King's College Hospital, has been good enough to report on the tumour shown in Fig. 148. It consists of a cellular matrix, composed for 184 EADIOGRAPHY the most part of large, round, or oval cells, having large nuclei, sometimes multiple. There are also a few myeloplaxes. This part of the tumour is sarcomatous in type. Set in this tissue are numerous masses of cartilage, fairly well formed, but with tumour cells (like those of the matrix) instead of ordmary cartilage cells. The tumour is a chondro-sarcoma. Spontaneous fracture is a not uncommon comphcation, and owing to the expansion of the bony framework, " egg-shell crackling " may be met with. Later, the growth may expand beyond the bony limits of the growth, and secondary deposits occur, the substances in which these are found depending upon the type of the primary tumour. The lungs and mediastinum are frequently the seat of secondary growths. The periosteal type of sarcoma is not at all easy to distinguish. It may Fig. 150. — Tumour of clavicle (Radiograph by Dr. R. W. A. Salmoud). Sarcoma of acromial eud of clavicle. This has the appearance of a cystic condition of the bone. It developed rapidly. appear as a decided shadow of about the density of the soft parts, arising from the surface of the bone. It involves the soft structures, extending into them in some instances. The periosteum may show thickening, which will be revealed radiographically. Myeloid sarcoma in its least malignant form may simulate a cyst of the bone. It is of slow growth, and occurs at the ends of long bones. Spon- taneous fracture may occur in this as in cystic disease. Hydatid cyst may also be met with. It is more chronic in its progress, and shows a well-defined, fairly regular outline. Carcinoma of Bone. — This is usually secondary to a primary focus elsewhere — in the breast, genito -urinary tract, etc. It is generally a late secondary manifestation, the bones most frequently afiected being the ster- num, ribs, and spine. The disease may also invade a large joint, or the shafts of the long bones become involved. The sacrum or iliac bones may also be DIFFERENTIAL DIAGNOSIS OF TUMOURS OF BONE 185 invaded. The presence of these secondary deposits is shown radiographically by rounded irregular shadows of varying density, generally lighter than the normal bone. In other cases the disease takes the form of cario- necrosis, when cavities filled with necrosed tissue are produced, and ap- pear on the screen or plate as lighter areas. Exostoses. — These show as projections, sometimes of normal bone tissue, and some- times of rarefied or unusually dense bone ; the situations in which they are met with are numerous, as in the ends of the long bones, bones of the feet, the pubis, etc. Chondromata. — -These may occur in any bone, but particularly in the long bones, and also in the bones of the fingers and toes. Fig. 151. — Exostosis of lower end of femur. Shows signs of inflammatory changes at end of exostosis, probably secondary to trauma. Differential Diagnosis of Tumours of Bone A brief summary of the commoner forms of tumour of bone and of the points which are most useful in diagnosis is necessary. It is also well to remember that there are no positively definite signs of any particular tumour. Clinical data and radiographic records should be taken together if the examination is expected to be of value. The appearance of a shadow of doubtful nature in one of the long bones raises most important questions of diagnosis. The benign cyst has recently been shown to be a comparatively common tumour of bone. The term benign is used in relation to the degree of malignancy and growth rather than as a pathological classification. Many of these so-called benign growths are myeloid sarcomata, which are peculiarly slow in the rate of growth. The tumours most likely to lead to difl6.culty in diagnosis are those which are found in the interior of the shaft of a long bone, or at its epiphyseal ends, and which have rarefied or replaced the osseous or medullary tissue, with or without expanding the bone, and which are situated within the osseous tissue of the bone. Such tumours may prove to be (1) central abscess, tuberculous or septic ; (2) gumma ; (3) hydatid cyst ; (4) benign cyst ; 186 RADIOGEAPHY (5) fibrous osteitis ; (6) enchondroma ; (7) endothelioma ; (8) secondary carcinoma ; (9) myeloma ; (10) sarcoma. The points to be considered are: (1) history; (2) physical signs; (3) evidence of disease or tumour in other parts of the body ; (4) radiographic appearances, and a correct interpretation of these. The chief of these, so far as our purpose is concerned, is the radiographic appearances, though all should receive attention. The points of importance radiographically are the site of the tumour in the bone, its density and consistence, whether subdivided by trabeculse, its outline, whether sharply defined and surrounded by a well-defined shell Fig. 152. — Traumatic myositis ossificans. Note the unchanged aspect of the bone. The ossification in the muscle bundles is quite distinct from the periosteum. of bone, whether the bone around is normal or rarefied, presence of deposits of new periosteal bone or sclerosed bone, the presence of a fracture, the evidence of erosion of the bone. Traumatic Myositis Ossificans. — A condition which arises in the sub- stance of a muscle secondary to trauma. It occurs most frequently in the arm or the thigh. The appearances are characteristic and must not be mistaken for sarcoma arising from the periosteum. Fig. 152 illustrates the typical appearances in this condition. Central abscess is generally accompanied by symptoms, however sHght, namely, pain and loss of power, indicating an inflammatory process, and occasionally by fluctuations in temperature. Eadiographically, the cavity is not as a rule strictly central, and the surrounding dense bone is unequal in its thickness. The outline is often indefinite, the cavity is not very clear, PLATE XXXI.— Tumours of Bone. «, Secondary sarcoma affecting upper end of femur, fracture through neck. The primary lesion was a periosteal sarcoma of humerus. h, Same case at an earlier stage. (Radiograph by Dr. N. S. Finzi.) c, Sarcoma of upper end of femur. The diagnosis in this case is doubtful ; it is most probably a myeloid sarcoma of very slow growtli. d, Sarcoma of upper end of humerus (inset is a photograph of the joint after removal). The humerus has Vjeen fractured probably as a result of manipulation, at or after the operation. DIFFERENTIAL DIAGNOSIS OF TUMOURS OF BONE 187 and there is an absence of trabeculae. The bone around is denser, and there is generally a deposit of new bone. Hydatid Cy.sL— This is very rare in this country, though it should always be kept in mind when considering obscure conditions. It shows as a sharply- rounded area less dense than bone. Benign Cyst is a much more common occurrence than was formerly thought. The fiist sign may be a so-called spontaneous fracture of the bone, this occurring as the result of violence of a mild kind. The appearances are characteristic. The cavity or cavities are situated centrally ; they fill the bone uniformly, the space indicating the cyst being clear and not sub- divided by trabeculae. There is little or no sclerosis of bone, and no periosteal thickening, though this may occur as a result of fracture. Fibrous Osteitis. — Probably always originates in early life. It is char- acterised by swelling and deformity, the latter being due to bending of the softened bone. The disease may be localised to one bone, the upper end of the femur being the most frequent site, when the bone is expanded. Skia- grams show expansion of nearly the whole shaft. There are great variations in density, and an appearance of subdivisions by trabeculse. These appear- ances lead in the diagnosis to confusion between this condition and myeloma. Secondary Carcinoma. — Radiographically, there may be seen a clear area in the middle of the shaft of a long bone or a rib, giving the appearance of a rarefied patch in the bone, covered by a thin shell of compact bone, and fading gradually up and down the shaft into normal bone. Myelo7na. — -They are most likely to be confused with benign cyst or with fibrous osteitis. They are generally found at the ends of the bones. Radio- graphically, the distinguishing features are the expansion of the bone and the subdivision by trabeculae. Sarcomata of Bone. — These are periosteal and endosteal. The former are often difficult to distinguish from inflammatory thickening or myositis ossificans traumatica. Medullary Sarcoma is probably the rarest of the endosteal tumours of bone. The bone is expanded with great rapidity, and the bony shell is 'often eroded. Erosion seen in a skiagram should always excite suspicion of the true nature of the disease. The appearance in a skiagram of a clear space in the shaft of a bone, expanding the bone unequally, and showing erosion of the bone substance, should lead to the suspicion of sarcoma. THE X-RAY EXAMINATION OF THE THORAX AND ITS CONTENTS The complete routine examination of tlie thorax includes an investigation of the bony walls, the heart and aorta, the lungs, the mediastinum, and the oesophagus. The bony walls have been dealt with in the chapter on injuries of bones, and the oesophagus in that on the alimentary system. For our present purposes, therefore, the routine examination of the chest consists of a scrutiny of the heart, the lungs, and the mediastinum by the methods of Radioscopy and Radiography. Radioscopy Radioscopy, or the examination of a patient with the fluorescent screen, is a method of great value, as a diagnosis can often be made from it alone, to be subsequently confirmed by radiographic exposures. To obtain reliable results it is essential that the technique should be complete. Technique of Examination. — Several methods are employed : 1. The Recumbent Position. — The patient may be placed on the X-ray couch, the tube working from below and the operator manipulating the screen. The position of the tube and of the diaphragm aperture are adjusted to suit the requirements of the case. It is essential to have a good X-ray tube of the proper degree of hardness, and an evenly-spread fluorescent screen. 2. The Upright Position, with the patient standing in front of the X-ray tube, is undoubtedly the best. For this method, a well-protected screening stand, all the parts of which work with ease and smoothness, is necessary. The particular form of stand varies with the desires of the operator, but in order that good results may be obtained a good stand is essential. A convenient form is illustrated opposite. A few minutes' con- sideration of the mechanism will familiarise the operator with its move- ments, and it need not therefore be described. A rectangular diaphragm is better than one of the iris shape, as with the rectangular form it is possible to examine in detail the roots of the lungs in their entirety. The room should be completely darkened, not even a glimmer of light being permissible when the tube is working. An open fireplace for heating purposes is not advisable, but if such is used, then efiicient steps must be taken to exclude light from it during the examination. It is also necessary to enclose completely the X-ray tube and valve tubes in a box or in black 188 PLATE XXXII. — Malignant Diseases of the Chest. a, Secondary deposits of sarcoma iu mediastinum and lungs. h, Lynipho sarcoma of mediastinum, extending outwards from root of lung towards the periphery, c, Secondary deposits of cancer involving mediastinal glands, lung substance, and pleura ; the diaphragmatic surfaces of the right lung and the liver are also involved. EXAMINATION OF THE THORAX 189 cloth, and even the front of the X-ray box must be covered with an opaque cloth, if reliable observations are to be made. These precautions taken, the operator should allow a few minutes to elapse in the darkened room before the current is allowed to pass through the tube, in order that the retina may become sensitive to the fluorescent appearance of the screen when the tube is working:. Fig. 153. — Upright screening stand, witli automatic stereoscopic movements of tube- and plate- holder controlled from the switch-board. Suitable for taking radiographs of the thorax. (Butt and Co.) The Routine Examination. — This should always be carried out in a definite order. The tube should be first centred over the heart, with the diaphragm opened to its widest limit. This enables a view of the whole of the thorax to be obtained. Then the tube should be carried well down, and the movements of the diaphragm examined for limitations on either side, and the presence of dullness at either base looked for. Next the heart and aorta are carefully scrutinised for abnormalities of size, shape, or position, or for the presence of pulsation in abnormal situations. 190 EADIOGKAPHY The tube should then be moved over to the right side of the chest, and the diaphragm of the apparatus closed laterally until a long slit aperture is obtained. This is carefully adjusted over the hilus of the lung for the detection of enlarged or cancerous glands. The appearance of the shadows at the root of the lung should be noted. Repeat the observation on the left side. Great care should be exercised in the examination of the apices of the lungs, both as regards the quantity of current passing through the tube and the observation of the apices them- selves. After one apex has been ex- amined a mental note should be made of the degree of the illumination present, and the tube then passed over to the other side. Differ- ences between the two apices should be carefully noted. The current pass- ing through the tube should be regu- lated by the operator, and this is best done by an adjustable rheostat close to his hand. With a soft tube and a small primary current, very fine detail in the lung substance can be made out. This is most important, for it is often by the examination of this detail that a diagnosis of early tubercular disease may have to be determined. Diagrams may be made on the lead glass in front of the fluorescent screen of any particularly striking departure from the normal, alterations in the diaphragm can be sketched in, and the amplitude of movement on inspiration and expiration noted. A permanent record of the amplitude of respiratory movements of the diaphragm can be obtained by getting the patient to inhale fully and hold the breath. An exposure is made. Then the patient exhales forcibly, and holds the breath while another exposure is made. The two Fig. 154. — Thorax of an adult, showing practically a normal condition except at the root of right lung where there is a slight increase of shadow. (ExposLire y-J-jj sec.) PLATE XXXIII. — Chest showing Pleural Effusion and its Absorption. Three plates from the same patient at intervals of several months. a, Plate on anterior asjiect of thorax, shows practically a normal condition. Note level of diaphragm on Ijoth sides. h, Effusion at left base. The level of the diaphragm on left side is much higher than in above plate. c, The eft'usion has been absorbed but the level of the diaphragm remains higher, indicating the presence of adhesions fixing the dome of the diaphragm on the left side. EXAMINATION OF THE THORAX 191 shadows on one plate show the degree of diaphragmatic excursion. All observations of this kind should be immediately transferred to paper on completion of the examination, and entered in the notes of the case. These observations are of the greatest value in all cases ; but if they are to be useful a note must be made at once, otherwise the personal element will enter largely into the case. Even mider the most favourable conditions this factor must be considered, since it is the great objection to all screen examinations. In no other region of the body are we so absolutely dependent upon screen examination of a patient. The trained eye of the observer may detect changes in movement in lungs or heart which it is impossible to record upon a plate. But radiographs which are taken instantaneously are of great value as confirmatory evidence of changes in the organs, and should always be taken to complete the examination. The importance of having a thoroughly reliable fluorescent screen must be borne in mind. It is also essential that the screen be smooth on the surface, and kept scrupulously clean. The lead glass protection should also be kept well polished, for even a trace of dirt or pencil mark on its surface may lead to trouble, the importance of this point being readily understood where fine detail is being dealt with. It is also of importance to have the patient perfectly still, especially when radiography is employed, since the slightest movement during the exposure may ruin the value of a plate. The screening stand should be connected to earth by a wire, in order to avoid giving the patient a shock from the electrical discharges which are given off from the tube and metal fittings when the former gets hard. Fig. 155. — Normal lower cervical aud upper dorsal vertebrfe, showing the position for demonstration of cervical ribs. The apical part of both lungs is also well shown. Radiography In radiography of the lungs for diagnostic purposes it is necessary to use a soft tube in order to obtain the best results. It is detail in lungs and not in bone that we look for. A soft tube of about 3-inch spark-gap will allow a large quantity of current to pass through it, and will give very good detail in the soft parts. Time exposures of any length are of no great value for diagnosis ; if we are to get plates which will to any extent reproduce what we have seen on the screen, the exposure must be exceedingly short ; in fact, the shortest obtainable is the best. With a powerful modern installation the exposure 192 KADIOGEAPHY may be cut down to t^ of a second. The resulting picture is of great value, because everything is absolutely sharp, the heart being represented in outline by the sharpest possible line. The diaphragm is also sharp, and may be caught in a stage of contraction. This is well shown in a print from a case of early phthisis (see Plate XXXV., Fig. b). The hilus of the lung is also well shown. The branching of the bronchi and larger vessels can be followed to the periphery, and if the tube has been in the proper condition a faint mottling all over the surface represents the lung substance. From a comparison of such pictures obtained from normal subjects it is quite easy to detect changes which occur in diseased conditions, especially in the very early stages of tuberculosis of the lung. Even with the most up-to-date apparatus it is still necessary to use an intensifying screen, if the exposure is to be of the shortest possible duration. With a screen of this kind quite good pictures may be obtained with much less powerful installations, but their diagnostic value in very early cases is not nearly so great. The important point in these very rapid exposures is that they reproduce one phase of what one sees when a screen examination of the chest is made, with all the movements of the parts eliminated, so that when compared with the result of a prolonged screening they afford valuable confirmatory aid to the making of a diagnosis. Plates taken "svith time exposures can only be of value when a gross lesion is present. Another point in favour of these rapid exposures is that involuntary movements on the part of the patient are not so likely to spoil the result. In radiography of the thorax and bones of young children there is always difficulty on account of movements during the exposures. The child has often to be held on the plate. The rapid exposure is of great value in such cases, for even when the child is moving a sharp radiograph may be obtained, with an exposure of t^ of a second. The exposure is so short that move- ment is practically eliminated and good detail is obtained. Short exposures are, therefore, particularly useful in radiography of the thorax. Attention to Detail. — In this branch of the work, and indeed in all branches, only the most careful attention to detail in all directions will aid us in the production of reliable pictures, and a good routine is essential. Mechanical contrivances which facilitate movements of apparatus, and enable us to reproduce at subsequent examinations the same relative positions of tube, patient, and plate, will be found of the greatest service. The fluor- escent screen should be adaptable for the ready insertion of the plate when an exposure has to be made. Since the work is conducted in the dark, all metal points should be insulated or the whole apparatus earthed, and all the controlling factors must be at hand. Nothing is more trying than work of this exacting nature with the factors out of order. Consequently, great care should be exercised in the selection of all apparatus, with all the features of which the operator must be perfectly familiar. It is important for the operator to have control of the X-ray tube when TECHNIQUE OF THORACIC EXAMINATION 193 screening. A convenient form of regulator is the Bauer air- valve, a most ingenious method of admitting a small quantity of air into the bulb, the pressure of a small hand-pump forcing it through a mercury valve. By this contrivance the operator can regulate the hardness to the requisite degree without stopping the examination. Experience in the use of the Bauer air-valve for regulation of the vacuum of the X-ray tube leads to the conclusion that unless great care is exercised in its manipulation the tube soon becomes hard, and requires to be constantly regulated when in action. Other forms of regulator may there- fore be useful, such as the Osmosis regulator, where a small gas flame can be used to soften the tube. The control pump for the gas supply may be placed at a point convenient for the operator. When neither of these regu- lators is available the operator must regulate the tube by the usual method of sparking until it is at the proper degree of hardness for the particular case he is examining. The vacuum can then be kept more or less constant by regulating the quantity of current passing through the tube by means of the regulating rheostat. It is a good practice to commence the screen examination with the tube slightly on the hard side. A prolonged screening will reduce the vacuum, and when a radiograph requires to be taken, it will be found that the tube has attained the requisite degree of hardness. It is an advantage to keep one tube for radiography and another for screening. The Bauer air- valve is figured in the chapter on apparatus (see page 46). The Bauer regulator is also attached to the valve tubes when these are used. The two hand-pumps controlling the valve and X-ray tubes can be placed within the reach of the operator. The control table may also be within easy reach. A foot switch to control the lighting of the room is also useful. Then the operator has all the factors under his personal control during the screen examination of the patient. A point to be insisted on is that in every case examined a consideration of all the factors in the case is essential, and a diagnosis should never be made on the X-ray appearances alone. The physical signs are most im- portant, and some guide should be given by the physician to the radiographer if the best value is to be obtained. The findings by X-rays are frequently only a confirmation of an opinion already formed. It is true that in some cases the extent of the disease may be greater than the physical signs in- dicated, or an area of disease may be shown to exist in unsuspected regions, but on the other hand radiography may fail to show a definite lesion when all the signs and symptoms strongly indicate its presence. The type of case which most frequently calls for a radiographic investigation is that of incipient phthisis. Tuberculosis of the lung in all its varieties and stages will fall to be examined, but it is the doubtful case which proves the value of radiography. Here the rapid exposures will help greatly in settling the diagnosis. The expert clinician can foretell changes which radiography may fail to demonstrate, but the fact of its failure does not negative their presence. The expert radiographer may be more accurate than the inexpert 13 194 KADIOGRAPHY clinician. The combination of the expert radiographer and the expert clinician cannot fail to enhance the value of the observations of each. Cases will occur when both may be wrong. Repeated examinations at intervals by both may show the changes at a later date, and the record furnished by radiography of the progressive stages of a disease must lead to the accumula- tion of knowledge valuable for both. The value of repeated examinations of the thorax in some diseases is shown by the results obtained at the Cancer Hospital, London. All cases of cancer of the breast and other parts are systematically examined at intervals, valuable evidence being thus obtained of the condition of the pleura, the roots of the lungs, and the mediastinum. The progressive changes caused by secondary deposits in the pleura, the lungs, and the mediastinum are frequently shown. Diseases of the Thorax A brief consideration of the pathology of conditions affecting the thorax and its contents is necessary before discussing the radiographic appearances and the differential diagnosis. This review must necessarily be brief, for it is not within the scope of this work to do more than mention the various forms, with a short reference to the macroscopic appearances of such diseases, their common situations, and some points of difference in their origin and spread which have a bearing on the radio- graphic interpretation. The conditions that will be referred to are : (1) Diseases of the lungs. (2) Diseases of the pleura. (3) Diseases of the heart. (4) Diseases of the mediastinum. (5) Malignant disease of the thorax, including tumours of the heart and pericardium, the lungs and pleura, the mediastinum, the oesophagus, the spine, and the chest walls. (6) Foreign bodies in the thorax. Diseases of the Lung's. — As these are classified and described in text- books on pathology and medicine, it will be sufficient to recall briefly the chief points which will be likely to aid the radiographer. Many of them are referred to in the section dealing with the differential diagnosis. Circulatory Disturbances in the Lungs. — (1) Congestion. — Two forms of congestion are recognised, the mechanical and the hypostatic, the latter being the one most likely to show signs on radiographic examination. All grades of change may be seen passing into consolidation. (2) Broncho-Pneumo7iia. — The lung is fuller and firmer than usual, on section, and the general surface has a dark-reddish colour. Projecting above the level of the section are lighter-red or greyish-red areas, representing the patches of broncho-pneumonia. These may either be isolated and separated from each other by uninflamed tissue, or they may be in groups, or the greater part of a lobe may be involved. The disease may pass on to the stage to PLATE XXXIV. — Chests showing Pui,.m').\ai{y Tuberculosis. a, Right apex showing advanced consolidation ; left apex involved but disease not so ad- vanced ; roots of lung both involved but more so on right. b, Left side of chest extensively involved ; both apices are involved ; heart small and ""vertical." These two cases are both affected by active tuberculosis. c, Healed tuberculosis of long standing ; both apices show signs of involvement ; roots of lungs show evidence of calcified glands. Patient had no active symptoms. DISEASES OF THE LUNG AND PLEURA 105 which the term splenisation has been given, when it may be accompanied by a condition of collapse of parts of the lung. (3) Chronic Interstitial Pneumonia {Cirrhosis of the Lung, Fibroid Phthisis). — There are two chief forms, the massive or lobar and the insular or broncho-pneumonic form. In the massive type the disease is unilateral, the chest of the affected side is sunken and deformed, and the shoulder much depressed. The heart is drawn over to the affected side, the unaffected lung being emphysematous, and covering the greater portion of the media- stinum. There may be dense adhesions, and the pleural membranes may be greatly thickened. In the broncho-pneumonic form the areas are smaller, often central in position, and are found most frequently in the lower lobes. (4) Lobar Pneumonia is classified by physicians amongst the specific infectious diseases, but for radiographic purposes it may be described together with the more chronic forms of pneumonia. Three stages of the process of inflammation are recognised : (a) engorgement, (6) red hepatisation, (c) grey hepatisation. In red hepatisation the lung tissue is solid, firm, and airless, it may be friable, and the surface has a granular appearance. Grey hepatisation is a further stage in the inflammatory process, and it may, though rarely, go on to abscess formation. The disease is usually confined to a single lobe of the lung, but the adjoining lobes may, however, be con- gested, and in some instances the whole lung or both lungs may become involved. (5) Tuberculosis of the Lungs. — All forms may be met with. Diseases of the Pleura. — These require to be briefly considered, because the occurrence of one or other of them may give rise to a difficulty in diagnosis ; and also in the course of a malignant tumour of the lung, pleurisy and effusion are common sequelae. The simple form of pleurisy is easily recognised. Heemorrhagic pleurisy may occur when carcinoma of the lung is present. Diaphragmatic pleurisy may be limited partly or chiefly to the diaphragmatic surface. It is often dry, but may be accompanied by effusion, either serofibrinous or purulent, which is circumscribed to the diaphragmatic surface. Serous or purulent effusions of any size confined to the diaphragm- atic surface are very rare. Encysted pleurisy may lead to a loculation of the resulting empyema, which will give a shadow that may be quite indis- tinguishable from that caused by a new gro\^i:h or a primary abscess of the lung. Interlobar pleurisy is another condition which must be borne in mind when considering a doubtful negative. Diseases of the Heart. — Tumours of the heart are rare, but there are conditions which may simulate tumour, and which must, therefore, be mentioned. These are tuberculosis and syphilis. Tuberculosis of the Heart.— This occurs as : (a) scattered miliary tuber- culosis ; {b) large caseous tuberculosis, extremely rare ; (c) sclerotic tuberculous myocarditis. The disease generally proceeds from a mediastinal gland, this fact being important from a radiographic point of view. Syphilis. — Gummata are the only manifestations of this disease likely to attract the attention of the radiographer in the cardiac region. 196 KADIOGEAPHY Diseases of the Mediastinum. — In simple lymphadenitis and suppura- tive lymphadenitis, the glands are large and infiltrated, but are not usually dense enough to cast shadows sufficient to complicate a diagnosis. Suppura- tive lymphadenitis may, however, lead to abscess formation, and then a large shadow may be found due to the presence of pus. Both these conditions may simulate tumour. Abscess of the mediastinum is not at all uncommon, .and may be of considerable size. It is secondary to an infective process, e.g. erysipelas, eruptive fevers, and tuberculosis. Indurative mediastino- pericarditis is a condition in which the pericardium may be greatly thickened by a great increase of the fibrous tissue. This may give rise to changes in the mediastinal shadows. Malignant Diseases of the Thorax. — The tumours most commonly met with will be considered first, then the rarer conditions, and finally tumours involving the bony structures composing the walls of the thoracic cavity, namely, the vertebrae, ribs, sternum, and costal cartilages, will be briefly considered. Tumours of the Heart are very rare. An enlarged, hypertrophied, or dilated heart may, however, complicate a diagnosis when a malignant process is situated in the near vicinity. Primary cancer and sarcoma are extremely rare. Secondary tumours — sarcomata and carcinomata — may occur, either directly or by extension from the pleura and pericardium. Calcareous patches occurring in a greatly dilated aorta may, where viewed laterally, simulate the appearance of secondary growths in the mediastinal glands. When these occur the outline of the dilated aorta is seen as a rule, particularly if there is an associated condition of arteriosclerosis, and these shadows should, therefore, be capable of differentiation from the more serious condition of growth. A hydropericardium may lead to difficulty when the pleura also contains fluid, both of these structures becoming involved when there are secondary deposits of mahgnant disease in the pleura. Tumours of the Lungs and Pleura. — Primary tumours are rare, and primr ary cancer or sarcoma as a rule involves only one lung. Secondary growths are not uncommon, and may be of various forms, generally following tumours of the digestive tract, the genito-urinary organs, or the bones, and, most frequently of all, cancer of the breast. The types most usually met with are in order of frequency : (1) scirrhus cancer ; (2) epithelioma, which may be primary in the bronchial tract ; (3) sarcoma ; (4) fibroma ; (5) enchondroma ; (6) osteoma (very rare). The lungs may also be involved in Hodgkin's disease. The primary growth generally forms a large mass, which may occupy the greater part of the lung. It may by extension outwards involve the parietal and visceral pleura. The tumour mass may necrose, and a cavity result. The diffuse cancerous growth may resemble a tuberculous pneumonia. The metastatic growths are nearly always disseminated ; they may vary from a mihary type to quite a large growth, and all variations in size may be met with in the same patient. The symptoms may be slight or marked according to the accessory lesions which accompany the new growth, such as pleurisy ; this may be dry or accompanied by effusion. PLATE XXXV. — Chests showing Pulmonary Tuberculosis. a, Post-mortem subject. Note fine shading iu lung substance. Tuberculous bronclio-pneumonia. h, Early tuberculosis of lungs, iDeribroncliial thickening, irregularity of diaiDhragmatic shadow on right side, with sharpness of all detail. Exposure -^^jj second, intensifying screen used. c, Acute general tuberculosis of both lungs (miliary tubercle). TUMOURS OF THE THORAX 197 Tumours of the Mediaslinum. — Cancer is the most common form of tumour in the mediastinum. There are three chief points of origin : the thymus, the lymph glands, and the pleura and lungs. Primary sarcoma is more frequent than primary cancer. Lympho-sarcoma and lymphadenoma frequently give rise to large tumours. Tumours of the (Esophagus. — The most common tumour is epithelioma, and it occurs more frequently in males than females. The middle or the lower third of the oesophagus is the most usual situation in which the growth is found. It is at first confined to the mucous membrane, but soon breaks through and extends into the mediastinal tissue, stricture occurring in the lumen of the tube. Later on, w^hen ulceration of the mucous surface occurs, the stricture may be less marked than in the earlier stages. In the course of the disease the oesophagus above the growth becomes dilated, and a degree of hypertrophy follows. The ulcer may perforate the trachea, the lung, the pleura, the mediastinum, the aorta or one of its branches, or it may erode the vertebral column. Tumours of the Spine. — Tumours, simple or malignant, may arise in connection with the spine, the ribs, the intercostal spaces, and the costal cartilages. These may by extension involve the adjacent organs, and when the lungs and pleura become implicated shadows are obtained which are indistinguishable from new growths of primary origin in those structures. Conditions involving the spine which may lead to error are : (1) Tubercular caries. In the early stages an inflammatory process leads to thickening and abscess formation which simulate new growths of the spine ; rise of tempera- ture and other signs of tuberculosis should be looked for. (2) Abscess following caries is a frequent cause of difficulty in diagnosis. (3) Sarcoma arising from the costal cartilages and sternum may lead to the formation of a definite cystic condition indistinguishable from hydatid cyst. A hgemorrhagic condition in the tumour may simulate the appearance presented by a cyst. Tumours of the Chest Walls. — Sarcomata in these positions are occasion- ally met with. They may be solid, or, when growing rapidly, may become cystic or hsemorrhagic, and when examined show shadows which may be mistaken for new growths of the lungs or pleura. Foreig'n Bodies in the Thorax. — Various forms of these may be met with, particularly in children. A foreign body should first be located by means of the screen, and stereoscopic radiographs taken for exact localisation. If an operation is contemplated, then the examination should be repeated just prior to the time of operation, in order to obviate the risk of change of position of the foreign body. The thorax and cervical region require to be carefully examined when a foreign body is suspected to be present. Lateral pictures are useful, particularly when the foreign body is located in the upper air passages. 198 EADIOGRAPHY Differential Diagnosis in Diseases of the Lungs The differential diagnosis of these conditions is always difficult, particu- larly from a purely radiographic point of view. The X-ray findings are usually shadows of abnormal growths, invading shadows representing the normal structures, and it is often on slight variations of these normal shadows that a diagnosis may be made. A fine departure from the normal may be the earliest manifestation of a commencing new growth, and its presence may be detected before physical signs or symptoms call attention to the presence of serious mischief. On the other hand, however, it is occasionally found that persistent symptoms, such as pain, slight cough, dyspnoea, may be present for months before the presence of a neoplasm can be detected by radiographic examination. This is particularly evident in the recurrent forms of carcinoma after operation, where pain at a fixed point may for a very long time be the only sign of recurrence. Later this may be followed by the demonstration of a gradually increasing shadow, or a slowly accumu- lating pleural effusion, indicating that the pleura has become involved. The occurrence of these infiltrating secondary carcinomata of the pleura is interesting. The extension is usually by direct continuity from the chest wall, the growth developing through the intercostal spaces, slowly involving the pleura on the parietal aspect, spreading along the internal aspect of the ribs, and forming fiat plaques which do not penetrate to any degree. These plaques are shown as fine shadows along the lines of the ribs. Fluid is slowly exuded into the pleural sac, and, later, the visceral layer of the pleura becomes involved, at a still later stage the lung itself becoming invaded by masses of slowly increasing size. In contradistinction to this it must be borne in mind that the secondary invasion of carcinoma may begin in the mediastinal glands or those at the roots of the lungs. It then spreads along the bronchial glands, and at a late stage of the disease we may find the pleura studded with plaques on its parietal and visceral aspects, with an accumulation of fluid in the pleural sac, the mediastinal glands enlarged, and the whole of the lung riddled mth growtns of various sizes. Radiographically, all these stages of secondary carcinoma may be shown in the same case if examinations are made during the progress of the disease. The various progressive stages of this form of malignant disease are well worthy of careful study, for all these forms are sure to require investigation. In the earlier stages it is extremely difficult to establish a diagnosis on radiographic evidence alone ; all the facts of the case require careful consideration, and other methods are helpful, particularly in some cases where tuberculosis may be the alternative diag- nosis, or where it may be an accompanying condition. The combination of the two diseases is rare, but they may occur in the same patient. Haemo- ptysis may be a determining factor in the diagnosis, especially if it occur to any extent. Haemorrhage to a marked extent from a secondary carcinoma is comparatively rare, whereas in tuberculosis it is often the first symptom to call attention to the disease. Simple Tumours of the Lung*. — These are very rare. Tumours of ? O bD 002 g c3 (^ W cS S o s:^ 'S o S g o