HX64057453 RD137 G12 X-ray observations f RECAP OBSERVATIONS FOR FOREIGN BODIES and their LOCALISATION BY HAROLD C. GAGE C. V. MOSBY COMPANY, ST. LOUIS RDI37 GIZ CoUcge ot pfjpsiciansf anb burgeons liifytavp D R. Mary L.H.A.Snow X-RAY OBSERVATIONS FOR FOREIGN BODIES and their LOCALISATION To M. le Docteur Beclere de rAcademie de Medecine, Chef du Service Central de Radiologie du Gouvernement Militaire de Paris. In appreciation of the X-ray Service of the French Army, and of much personal kindness and encouragement. X-RAY OBSERVATIONS FOR FOREIGN BODIES and their LOCALISATION BY Captain HAROLD C. GAGE, A.R.C, O.I. P. CONSULTING RADIOGRAPHER TO THE AMERICAN RED CROSS HOSPITAL OF PARIS ; ^ RADIOGRAPHER IN CHARGE, MILITARY HOSPITAL V.R. 76, RIS ORANGIS, AND COMPLEMENTARY HOSPITALS ST. LOUIS C. V. MOSBY COMPANY 1920 Printed in Great Britain Serial N° R. 275 Cross section /eve/s Sect/on 2d Section 31. ^.C.?. COMBINED LOCALISATION AND RECONSTRUCTION OF THE WOUND TRACT. The passage of the projectile is marked in each section by the thick line indicating the tissues and organs probably injured. The subsequent history of the patient gives the following : Empyema, subphrenic and perirenal abscess, duodenal fistula and urinary fistula. Frontis{iece PREFACE This small contribtttion to IVar Radiology was written by inviiation in June, 1(^17. It ivas to have been a chapter on the localisation of foreign bodies in a ivork that was being compiled for the American Council of National DefencCy but owing to the death of the Editor the publication was abandoned. The matter remains unchanged^ with the exception of some stnall additions and appendices. The Hospital at Ris Orangis has, during i<^ij and igi8y been largely used as a training centre, and it is in response to the requests of many visitors to the clinic that the book is now published. It formed the basis of the lectures given on the subject. These observations are based on the personal experience of the Author ivith the methods referred to in this book, con- stituting over 4. years application to the problems of war radiology (the first seven months were passed in an advanced ambidance within three miles of the line, the remainder has been spent at the base, apart from visits of detached duty), but for the majority of them, no originality is claimed; and it is impossible to give personal acknowledgment to all who have generously helped rne, or to the originator and every method mentioned. I should like, however, to acknow- ledge the great kindness and courtesy shown to me, and the information and experience so freely placed at my disposal, by my French colleagues. It is largely owing to their keen appreciation of the questions involved, and their unwearied application to the solution of the problems presented, that much "progress has been made. To Dr. Belot and Dr. Fraudet I am indebted for the privilege of inserting their method of localisation of foreign bodies in the eye, from their original work in the '^Journal de Radiologic et d Electrotherapies ' To Mr. H. Franze my thanks are due for the excellent drawing of many of the illustrations ; also to my assistants, Mr. Beer, who provided several of the illustrations, and Miss Slater, zvhose help in revising the MS. has been invaluable. INTRODUCTION It is almost superfluous to state that accurate localisation of foreign bodies is of prime necessity to the surgeon who is to remove them. No one realises this more than the surgeon who has wandered through the tissues in a fruitless search for a foreign body which he knows is somewhere there, but the exact location of which has not been made clear to him. In other words, a localisation, to be practical and successful, must not only be accurate but must have been recorded on the patient in such a manner as to be clear to the surgeon as well as to the radiographer. Moreover, it is quite essential that the surface marks from which the foreign body is oriented be so situated, and of such number as to obviate, in so far as possible, the errors that may arise from the impossibility of re-establishing on the operating table the exact position occupied by the limb or body during localisation on the X-ray table. For example, a report from the radiographer that the foreign body lies so many centimetres below a mark on the skin is insufficient, and to a certain degree dangerous, in that it affords an inexperienced surgeon an unjustifiable confidence in his ability to find it. The additional four or five minutes on the X-ray table needed to record a localisation from which a surgeon may work with certainty are much better spared tha n a longer time spent by the operating team in an ill-directed search — not to mention the consequent unnecessary mutilation. Two years experience with the exceedingly simple and ingenious method of Localisation by Three Intersecting Lines, developed and perfected by Mr. Gage, has convinced the writer that it is the most practicable for the majority of cases. The three lines joining the three pairs of marks on the skin are readily pictured, and the position and relations of the foreign body consequently more clearly visualised than is possible by any other system. While mechanical aids may be used in addition they are very rarely necessary, which adds greatly to the practicability of the method for institutions where the cost of such apparatus would not warrant its possession. A proof of the value of the method is the remarkable record made by it in the hospital at Ris Orangis. A total of 306 localisations Introduction resulted in 302 successful removals ; in two cases the search was abandoned on account of the danger of wounding important anatomical structures, and only two localisations were unsuccessful. Mr. Gage's experience, his great skill, and his knowledge of physical problems, lend great weight to his remarks and observations. No one can realise this more than those who, like the writer, have had the great privilege and the pleasure of working with him. JOSEPH A. BLAKE, Colonel, Medical Corps, U.S.A. X-RAY OBSERVATIONS FOR FOREIGN BODIES AND THEIR LOCALISATION General Installation. The equipment for the generation of the electric current necessary to operate the X-ray tube for locaHsation of foreign bodies needs nothing special beyond the requisites for or- dinary radiography and fluoroscopy. If the opportunity for choice occurs a coil outfit should be selected, as it un- doubtedly has points in its favour for use in the field as against the high tension transformer.* For general hospital work, where instantaneous pictures of organs in motion are a daily necessity, the latter is indispensable, but the percentage of this work is almost nil in war surgery. The coil should be given preference, briefly for the follow- ing reasons: it is easily portable, and gives better screen illumination for a given milliampereage, with a diminished risk •of burns to both patient and operator; the proportion of fluoroscopic examinations is much greater than that of plates. Details needing special attention apart from the instrumenta- tion of any given method of localisation are: first, a rigid X-ray table, with a convenient under-table trolley to carry the tube in a well protected shield or box, and giving longitudinal and cross displacement that can be definitely controlled and measured; second, and almost first in importance, the tube holders must be such as to give convenient means of exactly centering the tube to a mechanical closing diaphragm that shall -close absolutely in a central position. While many other desirable features might be added, these are imperative, and with them the most exacting work can be done with absolute certainty. * The advent of the new radiator self-rectifying Coolidge tube and the American Army Portable Unit, is such an advance as to constitute a xevolution in X-ray apparatus ; its simplicity, efficiency, and portability are .such that it may, and probably virill, supplant the coil. 2 X-Ray Observations for Foreign Bodies Darkening the Room. Where possible ample room should be provided for the X-ray department. The tendency is to give any small odd room over to this work, which can but cripple the efficiency to a serious extent. In the X-ray room, work has to be done of the most tedious and exacting nature, which under un- favourable conditions becomes intolerable and shows itself in the results. Let it not be forgotten that the X-ray department in war surgery is second in importance to nothing in the whole hospital, and its quarters must be good, airy, and spacious; many people must work there; patients are frequently very sick, and the wounds smell badly; besides, the room is often required for an operating room for removal of foreign bodies under screen control, and for the reduction of fractures. Darkening and ventilation are difficult problems, but for the sake of efficiency they must be solved. The window should always be accessible to be thrown open for airing between cases, while the operator wears coloured spectacles to preserve the adaptation of his eyes. The artificial lighting should be under control by a small resistance, in order that while changing position of the patient, etc., it may be dimin- ished to a minimum ; it should be preferably of red or violet colour. In advanced field use the cryptoscope is invaluable,, and its best form will be described later. But whether the cryptoscope is used or the room darkened, care must be takew that not one penetrating ra}^ can enter, in order that in a foreign body examination the smallest fragment may not be missed. Protection. This must, of course, be efficient. First see that the tube is enclosed in a ray-proof cupule or box, which the radiographer should test personally with the screen and if necessary reinforce. To test the lead glass of a fluorescent screen, should a second screen not be at hand, project the rays through the glass, and if fluorescence is produced discard for a denser glass or add a second. Handle covers and gloves should be lined and not made of plain lead impregnated rubber. Work X-Ray Observations for Foreign Bodies 3 with as small a diaphragm opening as possible ; do not place yourself or your hngers in the direct beam, and you are safe. Diaphragm. The type to be preferred is one that closes with one controlling handle and always on its exact centre. It should close with ease in order that the tube may not be displaced at the same time. It will be found that few, if any, of these diaphragms are in themselves efficient ; they are always flat, and as hard penetrating rays are mostly used, many secondary rays are generated, producing diffusion and spoiling the definition ; consequently, it will be found of infinite advantage to provide in addition a simple cylindrical diaphragm mounted on sheet lead to place over the mechanical one. Provide a cylinder of the smallest diameter that will suit you, and you will be amply repaid in the clear definition and in the assurance that you are letting nothing pass. The Tube. Although in some localising methods it is preferable to use the overhead tube or vertical screening stand, much of the work will be carried out — general screening, operating with fluoroscopic aid, etc. — in the horizontal position with the under-table tube. The choice of the tube is of some importance; therefore let it be a well formed, flexible tube, preferably water cooled, for it is worth much during an operative pro- cedure to be relieved of all anxiety as to its welfare and efficiency. When formed, guard it and nurse it well. The focus need not be of the sharpest, but must not be too wide. In choosing a tube, should it not centre well, discard it, as it will lead to inaccuracy and disappointment. See always that its anticathode and anode are not accidentally disconnected, or its wandering focus will lead to confusion. A foot switch control is almost indispensable and may save you many steps and tubes. The penetration of the tube for general observation should be represented by a spark gap of about 5)^ to 6 in., although a softer degree will give better contrasts, and a 7 and 8 in. 4 X-Ray Observations for Foreign Bodies gap may be required in observations for foreign bodies superimposed on the vertebrae, and for examination of stout patients. An adjustable series spark is a valuable addition for regulating the tube penetrations and should always be fitted to the apparatus. Foreign Bodies — Their Nature and Shadow. The visibility of a foreign body by X rays on plate or Illustration I. Radiographic appearance of wood in the soft tissues of the thigh. Equivalent spark gap 2 inches, 4 milliamp. -minutes. screen is (apart from its size) entirely a question of its atomic weight, in contrast to that of the tissues in which it rests. For this reason different metals and materials throw a different degree of shadow. It must also be noted that change in the penetration of the tube will change the apparent density of a X-"Ray observations for Foreign Bodies 5 given material. This is valuable in the differentiation of calcified glands, superimposed bones, bone fragments, etc. Pieces of shell, shrapnel balls and rifle bullets, nails and metallic refuse from hand grenades, and lead splutterings will be easily detected, while thin bullet casing and fragments of aluminium are more difficult — the latter almost im.possible if "% ERRATUM P jge 5, third line from bottom, should read "Wood, not frequently present, etc," instead of " Wood, not infrequently present." Illustration 2» The casing of a rifle bullet stripped and remaining in the tissues. not of considerable size and in a thin part of the body. Clothing throws no shadow unless it is impregnated Jwith some denser material. Wood, not infrequently present in the soft tissues, is not discoverable with the screen, but may be found by plating, if the tube is of low penetration. (Illustra- tion I.) 4 X-Ray Observations for Foreign Bodies gap may be required in observations for foreign bodies superimposed on the vertebrae, and for examination of stout patients. An adjustable series spark is a valuable addition for regulating the tube penetrations and should always be fitted to the apparatus. Foreign Bodies — Their Nature and Shadow. The visibility of a foreign body by X rays on plate or pp '^^^^^^1 ' Illustration I. Radiographic appearance of wood in the soft tissues of the thigh. Equivalent spark gap 2 inches, 4 milliamp.-minutes. screen is (apart from its size) entirely a question of its atomic weight, in contrast to that of the tissues in which it rests. For this reason different metals and materials throw a different degree of shadow. It must also be noted that change in the penetration of the tube will change the apparent density of a X-"Ray observations for Foreign Bodies 5 given material. Tills is valuable in the differentiation of calcified glands, superimposed bones, bone friigments, etc. Pieces of shell, shrapnel balls and rifle bullets, nails and metallic refuse from hand grenades, and lead splutterings will be easily detected, while thin bullet casing and fragments of aluminium are more difficult — the latter almost im.possible if Illustration 2. The casing of a rifle bullet stripped and remaining in the tissues. not of considerable size and in a thin part of the body. Clothing throws no shadow unless it is impregnated iwith some denser material. Wood, not infrequently present in the soft tissues, is not discoverable with the screen, but may be found by plating, if the tube is of low penetration. (Illustra- tion I.) , 6 X-Ray Observations for Foreign Bodies General Examinations. The search for foreign bodies should not be confined to the region of the wound, but a thorough general examination should be made, especially if there is only one wound, i.e.^ the wound of entrance. Never be led to suppose that a wound of exit negatives the possibility of a lodged foreign body. Many bullets strip their jackets in transit (Illustration 2), or Illustration 3. Sinus injection with bismuth simulating a lead foreign body with splutterin^s. shell fragments are separated by contact with bony structures. A foreign body may travel a great distance and take a very unusual course. In a case with a wound of entrance over the left deltoid, a shrapnel ball was recovered from the superficial tissues of the left buttock, having traversed the length of the body externally to the ribs. The case was X-Rav Observations for Foreio;n Bodies to' reported negative for foreign bodies on several occasions. Ultimately the ball manifested itself by causing an abscess. In the examination for foreign bodies errors easily occur, ■due to buttons on the clothing, coins or articles in the pyjamas pocket or round the neck, pins, etc., in dressings, or ■drains. Therefore all gowns should be tied with tape, and dressings be fixed with adhesive, or the parts absolutely ■denuded. Bone-plates fixing fractures, wire sutures, and Murphy's buttons must not be confused, and accumulations of metallic ointment, iodoform, or bismuth paste, show a very decided shadow easily misinterpreted. (Illustration 3.) Photographic Faults. When reading plates, one must bear in mind photographic faults caused by air bubbles in development or imperfections in the emulsion ; flaws in intensification screens can be a further source of error. Anatomical Densities. Attention should be given to the possibilities of either fluoroscopic or radiographic misinterpretation of the shadow cast by calcified glands, gall stones, stones in the kidney ureter and bladder, phleboliths, or superimposed bones, such as the pisiform, the spinous processes of the vertebrce, rsesamoids, the superior margin of the acetabulum, etc., but with care these can be differentiated by their comparative ■densities. When the fluoroscopic examination is uncertain a plate should be taken. With organs in motion, when it is not possible to take instantaneous radiographs, fluoroscopic observations are more reliable. Tube Centering.* In all radiographic technique the position of the tube in relation to patient and plate is very important. In no instance is it more so than in localising foreign bodies, to accomplish w^hich it is necessary to isolate and use the central vertical beam of rays (or normal ray, as it is termed) ; and at * Archives of Radiology and Elcdrothciapy, May, 1918. 8 X-Ray Observations for Foreign Bodies times, to note its incidence on the plate, screen, or patient. Most modern tube carriers and diaphragms have a mechanical attachment, which enables this adjustment to be made with ease. By this appliance the tube can be moved in any direction, until it is so placed that the normal ray passes through the centre of the diaphragm. Illustration 4, Fig i, shows (a) the anticathode, (b c) the normal ray passing through (m) a tube, in which are (77, n'). Fu3 I Fcfl 3 X ' f^^ ^A> mm ^fr Illustration 4. two sets of cross wires, and {F.S.) a small fluorescent screen. (/) Shows the appearance on the screen when the tube has been accurately centered, the shadows of the two crosses being superimposed on the screen and forming one image only ; {g) illustrates the screen appearance before centering. When centered, the apparatus (m) is removed and replaced by the diaphragm (/?) (Fig. 2), which closes down on the same X-Ray Observations for Foreign Bodies 9 centre. Fig. 3 shows a convenient method of centering an under-table tube or verifying its correctness. On the table top is placed a small papier mache box (a lady's powder pufT box will do well), across the top of which two wires are stretched at right angles, while from their intersection hangs a smalt Illustration 5. a, Anticathode of tube. 6, Path of normal ray. ni i?,Cupule and dia- phragm in position. ,ij, A disc of cardboard, aperture in the centre I in. in diameter. /, A smaller disc, with tiny central perforation, and second hole for the return of the cord supporting the plumb-bob /. In use the tube stand is adjusted until the cord hangs in the centre of the perforation k, when the plumb-bob may be lowered and the incidence of the normal ray recorded. This simple contrivance can be left attached, the metal portion withdrawn to the side during exposure. plumb-bob on a fine cord dipping into oil, with which the box is partially tilled. If the tube is now brought under this- 10 X-Kay Observations for Foreign Bodies small contrivance, and its projection on the screen viewed with the diaphragm closed down, a correctly centered tube will give the appearance shown at O, while a badly centered tube that shown ^iK. It is impossible to give too much emphasis to the importance of accurate centering. When it is desirable to record on a plate or limb the inci- dence of the normal ray, or to adjust cross wires to it, when using the overhead tube, two pieces of cardboard and a plumb line will suffice admirably. Illustrations 5 and 6 show their preparation and adjustment. Fig. I. Fi3. 2 Illustration 6. Vertical and lateral adjustment. Provisional Localisation at First Observation. When a foreign body is found, the diaphragm should be closed down, and the adjustment made to include the foreign body in the narrow beam of rays projected vertically from the lube. A small metallic circle on the end of a wooden handle may now be inserted under the screen until its image is pro- jected as encircling the foreign body; the skin may be marked through this ring with an indelible pencil, and the ring with- X-Ray Observations for Foreign Bodies 1 1 the difference Q^ Q2 — Pi P2 should be exactly half h. If it is less than half k, the wires should be separated ; if it is more they must be brought nearer together, until, on testing as before, the adjustment is found to be correct. In using the apparatus, the foreign body {F, Fig. 2) is first found with a small diaphragm opening, and the tube is shifted until the normal ray passes through it ; the point of emergence is then marked on the skin. If it can con- veniently be done, the screen is brought close down to the skin (in this position the marking is facilitated if a perfoi'ated screen is used). The diaphragm is then opened and the tube shifted until the shadow' of one of the wires (/^i, Fig. 2) passes through a definite point in the foreign body, and the position of this shadow (G) is marked on the glass of the screen with ink or a grease pencil. The tube is shifted and the shadow^ of the second wire {JV2) made to pass through the same point of the foreign body ; this second position (//) is marked on the screen as before. Then the depth of P below the sci'een is twice the distance G H. If it is not feasible to bring the screen into contact with the surface of the limb at the point of emergence of the normal ray through F, the best method is to place a small metallic body at this point (see M, Fig. 3), so that the shadows of F and M are exactly superposed. Then, by shifting the tube as before, the points on the screen where the shadows of the wires pass through M are marked, as was previously done for F ; the distance/ A' is also measured and subtracted from G H\ this difference multiplied by 2 is the depth of F below M, i.e., below the marked point on the skin. Fig. 4 (Illustration 8) shows a chart prepared in this way, where four different foreign bodies in the region of the hip are X-Ray Observations for Foreign Bodies 15 clearly shown, with their respective depths. Such a chart is. best made on celluloid, as explained below. Stereoscopic Tracings from the Screen. Such tracings are easily made. Of course they are not sO' good as plates, but if from pressure of work, or for any other reason, plates cannot be taken, and the relation of a foreign Illustration g. The tube is in position for antero-posterior plating; it easily slides out and into the lateral position. body is desired to some bony landmark, this procedure can be used to advantage. The tracings are drawn on celluloid, as previously described-; the usual stereoscopic displacement of the tube is made: 1 6 X-Rav Observations for Foreign Bodies fe' between the two tracings as for plates, very little work is required, a few bold outlines of the bon}^ landmarks and the foreign body accurately drawn will suffice, and it is surprising, with a little practice, how easy they are to produce and what useful and accurate information can be obtained. (Illus- tration 8, fig. 5.) Many still prefer the old method of plates at right angles, but it is fast being discarded, owing to the ambiguity involved when the foreign body is not in the same plane of projection on the two plates. To get satisfactor}^ results by this method the normal ray should be centered through the foreign body in both directions, when the information given is reliable, although insufficient if the foreign body is not near some anatomical landmark, shown on the plate. Reference to Illustration 9 will show a simple antero- posterior and lateral tube carrier (designed by the author) that insures the same projection. It is extremely useful. Observations on Foreign Bodies. In making the first observations on foreign bodies, much expense and time can be saved by having a number of sheets of celluloid cut to a size which will drop into the frame of the fluorescent screen. Upon these celluloid sheets the position of foreign bodies may be traced with a grease (or glass) pencil. These celluloid tracings ma}^ afterwards be retraced on to paper. In this way a great economy of plates may be effected, and, in most cases, an equal amount of information obtained. Tracings whth the Cryptoscope. These can easily be made by placing the sheet of paper on a thin flat board and using a pencil, all but the point of which is enclosed in a metal holder; by approaching the cryptoscope as close as possible to the patient the enlargement of the image is reduced to a minimum, while care in preserving its hori- zontal position secures a projection free from distortion. (Illustration 10.) Care should be taken to work with a small diaphragm, and X-Ray Observations for Foreign Bodies 17 the hands should never be allowed to come into the fluorescent area ; good gloves and full protection are imperative, and should be practised only when the exigencies of the service demand it. Illustration 10. Making tracings with the cryptoscope. For the clearness of the illus- tration the cryptoscope is not brought near the tracing. The Use of Bromide Paper. The economy offered by bromide paper is most important c 1 8 X-Ray Observations for Foreign Bodies in war, particularlyin view of the comparatively large quantity that one can transport. It is quite possible to make very good radiographs with rapid bromide paper, if an intensification screen can be used. Seventy-five per cent, at least of the graphs of foreign bodies can be taken on paper. Bromide prints made in this way are particularly useful, when only one copy is required to accompany a patient evacuated to another hospital. (See Appendix II.) Pierced Screen Localisation.* This method is very useful, exact, and of extreme simplicity. It requires a small fluorescent screen, pierced with a hole in Illustration 1 1. its centre (Illustration ii), intersected by a cross {d) to aid the centering of the foreign body. Through this perforation passes a thin cord, to which is attached a small lead pellet This cord can be let out or shortened by the shaft {m) on which it is wound, h is a travelling bar supporting a wire {w). The whole is held horizontally over the patient by attachment to the upright (a), and is hinged as indicated in the illustration. In use the foreign body is carefully centered under the cross, and the skin is marked through the aperture by a small stick dipped in ink, the lead pellet is now removed from the * Hirtz (Gaiffe, Paris), Arch, de Med., 1916. X-Ray Observations for Foreign Bodies 19 small receptacle ;/, and sufficient cord released to allow it to just touch the skin, as c, i; the apparatus may now be turned up (Fig. B); on its underside is fixed a measure, against which the distance from screen to patient is read off; this is noted, and the board is again lowered. The tube is now displaced any distance at right angles to the sliding wire w, which is then adjusted to bisect the displaced shadow of the foreign body (/). The patient's limb is now moved aside, the tube operated again, and the lead pellet lowered until its shadow is bisected by the wire w, as was the shadow of the foreign body ; the pellet now occupies in space the position recently occupied by the foreign body in the limb; it now simply remains to lift the apparatus again on its hinges and read off the depth of the foreign body. Subtracting the distance previously measured from screen to patient gives the depth of the foreign body below the mark on the skin. GEOMETRICAL LOCALISATIONS. Localisation by Triangulation. Originated by Sir James Mackenzie Davidson, this method forms the basis of most of the numerous localising appliances. It is very simple, and in the hands of careful workers is very exact. When used in detail as stipulated, with the cross thread localiser, it is probably the only method applicable to tiny foreign bodies that cannot be seen on the screen, or are in inaccessible situations, such as those embedded in the eye. Briefly stated, the process is as follows (Illustration 12, Fig. i). Centre the tube carefully under the foreign body with the diaphragm well closed down, and mark the position of the shadow on the screen (if it is large, mark one corner). Now mark on the patient's skin a dot corresponding to this shadow, and it is obvious that the foreign body is situated vertically below this mark, and an incision carried sufficiently •deep must reach the foreign body. To find at what depth, the diaphragm should be opened wider and the tube displaced a tnown distance (say 10 cm.), and the shadow of the foreign 20 X-Ray Observations for Foreign Bodies body will be displaced in the opposite direction; now mark^ in its new position, the identical corner of the foreign body previously marked. With a pair of dividers, carefully measure this distance {bd), and write it down, with the distance {ac) that the tube was displaced. The only further measurement required is the distance from screen to anticathode {ab). Illustration 12. With these factors known, the depth of the foreign body below the screen is found by multiplying ab by bd, and dividing by the sum of ac and bd. From the results should be subtracted any space between the patient's skin and the screen. The linear path of the rays can be constructed X-Ray Observations for Foreign Bodies 21 geometrically on paper if preferred, using a hard pencil with a sharp point, so that the lines may be as fine as possible and not obscure the intersection. Many forms of mechanical apparatus, such as that shown in Illustration 13, have been constructed to do away with the necessity of calculations and drawings, and other sliding rules have been devised to give Illustration 13. the depth, in reading on a scale, for a definite tube and screen distance and tube displacement. When working by this principle it is as well to work to definite distances, such as 50 cm. from the tube to screen and 10 cm. tube displacement. It leads to accuracy, and me- chanical attachments can be fitted to the table to enable the tube displacement to be made in the dark. 22 X-Ray Observations for Foreign Bodies When desirable, stereoscopic plates can be taken, and a localisation made at the same time by replacing the screen by plates in contact with the patient, the only difference in technique being that the tube is displaced 3 cm. to the left of the central position for the first exposure, and 3 cm. to the right of the central position for the second (see Illustration 12, Fig. 2), In this manner the surgeon can avail himself of the anatomical localisation given by the stereoscopic plates at the time of operation. Tiny Fragments. Fragments too small to see on the screen, which yet must be removed, are best located by the complete Mackenzie Davidson technique.* The principle is as previously described,, but as the foreign body cannot be centered, means must be resorted to to localise it wherever it may fall upon the plate. To accomplish this, the plate must first be tied up with wire as one w^uld tie up a parcel, with the cross wires intersecting at the centre of the plate, or a frame or drum, with two wires affixed crossing at right angles, may be devised on which to place the plate. If an under-table tube is to be used, means must be provided to centre the anticathode immediately under the intersection of the wires ; this can be accomplished by adjusting a plumb-bob to overhang the centre of the anti- cathode b}^ an arm and scaffold that travels with the tube, or the cross wires may be placed upon the surface of the body and the tube centered by placing the screen on top. Which- ever way it is accomplished, the skin must be marked with the same cross lines, and a small coin or metallic marker put in one quadrant and the same marked on the skin for identifica- tion later. The wires should be placed precisel}^, so that one crosses the long axis of the body horizontally and the other verticall}^, and the tube displacement should be made across the body. Two plates are now taken, the first with a displace- ment of the tube 3 cm. to the left and the second 3 cm. to the right of the centre, or one plate can be used with the double exposure on the same plate. When developed, the shadow of * " Localisation by X-ray and Stereoscopy " (H. K. Lewis and Co.,Ltd.,London). X-Ray Observations for Foreign Bodies 23 the foreign body will be found to have changed its position relative to the cross wires on the two plates taken, or two shadows will be found on the one plate. When dry, take a piece of transparent paper and place it on the plate, accurately mark in the cross lines, the impression of the foreign body, Illustration 14. the indication of the marked quadrant, and the second shadow of the foreign body if one plate was used. If not, place the tracing on the second plate with the lines in register, and add the second shadow from that plate. 24 X-Ray Observations for Foreign Bodies Armed with this tracing, go to the cross thread apparatus and place the tracing in register with the cross on the table of the apparatus (Illustration 14) ; adjust the height of the arm that carries the threads and indicates the two positions of the anticathode. Adjust this exactly to the height corresponding to the distance from anticathode to plate. From the notch to the left carry the thread to a chosen point of the foreign body traced on the paper to the right, and the right hand thread to the same point on the left. Where the lines cross is the position of the foreign body. Now take the indicator pro- vided with the apparatus and adjust it to the height of the cross in the threads, and read off the depth of the foreign body on the vertical scale. Then place the vertical scale on the cross line of the table that forms one side of the quadrant in which the cross threads fall. Measure with dividers, at .the level of the cross in the thread, the distance of this cross from the vertical scale. Repeat in respect to the second line of the quadrant. Now draw on the tracing, at the distances just ascertained, two lines parallel to those from which the measurements have been made. The intersection of these lines gives the point vertically below which, at the depth ascertained, the foreign body lies. The information is now complete. Now go to the patient, identify the quadrant, and mark in your data. Additional Procedure Necessary for the Eye. Before taking the plates for eye localisation a certain pre- paration of the patient is necessary. First, a few drops of novocaine may be dropped in the eye to allay irritation, if present. Then a small piece of fine lead fuse wire should be taken, bent double to avoid a sharp surface, and affixed to the cheek so that the folded end can be placed in contact with the lower e57elid vertically below the cornea. Notes must now be made of the exact position of this end, its distance below the centre of the cornea being observed from the frontal position, and its distance in front of or behind the centre of the cornea obtained from lateral observation. These measurements should be very accurately ascertained with dividers, as it is in relation to this identification point that localisation calculations are X-Ray Observations for Foreign Bodies 25 made. It must be done when the patient is in the position in which the radiographs are to be taken, with the visual axis parallel to the horizontal wire. To keep the gaze steady, while the plates are being taken, a bright object should be placed at a distance and exactly in front of the patient, at which he should look during both exposures. Lateral plates are taken, the cross wires being arranged with their intersection in front of and below the eye, so that the foreign body shall not be obscured by the wire. The tube must, of course, be carefully centered to the intersection of the wires. From plates so taken the relation- ship of the foreign body to the point of the lead wire can be absolutely determined, and the relationship of the lead wu-e to the cornea being known, the position of the foreign body in the eye can be definitely stated. The use of a model eye of a definite enlargement, and the necessary multiplication of the localisation figures, will help materially to decide the anatomical situation of the foreign bodv, and the possibility of its removal. The same technique, if desirable, is practicable ni anatomical localisation in other parts, employing any metallic indicator placed on the skin, or choosing a body landmark in the radiograph sufficiently distinct to be easily identified. General observations on foreign bodies in the eye can be made by taking a small lateral plate, wnth two exposures on the same plate, one with the patient looking down, the other •looking upwards. If the foreign body is in the eye itself, two shadows will be shown, unless it is situated in the axis of rotation; if it is in this axis there will be no duplication of the shadow. Otherwise, the position of the foreign body is •shown by the movement of the shadow. If the movement is backwards and downwards, it lies in the posterior superior •quadrant ; if downwards and forwards, in the posterior in- ferior quadrant ; if upwards and forwards, in the anterior inferior quadrant ; if upwards and backwards, in the anterior superior quadrant. An antero-posterior plate taken with a small fine wire cross, with its intersection central to the cornea Avill give additional information. This is a very specialised 26 X-Ray Observations for Foreign Bodies branch of the work needing particular care, and should only be undertaken by those possessed of the necessary know- ledge and experience. Dr. Belot and Dr. Fraudet have developed the above method with a special technique that gives a very accurate localisation and necessitates very little additional apparatus. Their pro- cedure is divided into two sections — exploration and precise localisation. A lateral fluoroscopic examination is made first, and the whole area carefully studied with a very small diaphragm opening ; foreign bodies may be found in other parts of the head and face, and by rotation of the head it is easy to decide roughly their position. This examination is necessary to prevent confusion, should there be more than one in the region. The head is now placed in a lateral position for the examina- tion of the eye in question. With the screen in contact with that side of the face, the tube is adjusted so that the normal ray shall pass through the orbital cavities; this position is easy to identify by the bright, ahnost oval patch appearing just posterior to the nasal bones. If a foreign body is found here, it remains to determine whether it is in the globe; this can be ascertained by telling the patient to look up and then down. The movement of the foreign body may then be interpreted; if it moves m the same direction as the eye, it will be in the anterior hemisphere, and if against it, in the posterior hemisphere. Further differentia- tion will be necessary, because a foreign body in the muscles producing the movements of the eye will also be displaced; this will be dealt with later. Care should be taken to exclude the possibility of foreign bodies in the eyelids. Should the shadow of a foreign body be seen very anterior, and moving rapidly on the patient's opening and closing the eye, this, location may be suspected. The parts may be individually immobilised during the screen examination; from such pro- cedure a diagnosis can be formed. Much useful additional and corroborative information can be obtained by a supple- mentary antero-posterior examination. - X-Rav Observations for Foreign Bodies 27 For the exact localisation five radiographs are required, three lateral and two antero-posterior. It is necessary for this method that the sight be preserved in one eye, and that the wounded eye shall have retained its mobility. It may then be assumed (should the injured eye not have retained sufficient sight) that the two eyes will make identical movements. The eye is regarded as a sphere whose Illustration 15. Position of the patient on the table with the rule and movable lamp to direct the gaze of the patient. Tunnel under which to slide the plate. ai. The angle swept by the eye when looking up. a2. The angle swept by the eye when looking down. a. p., the cross wire over the plate. movements are those of rotation about a centre which remains- fixed; a foreign body in the eye will make movements definitely^ related to those of the eyeball. The comparison and study^ of successive radios, between which the eye has been rotated in a definite sense, will give data from which an exact localisa- tion can be made. 28 X-Ray Observations for Foreign Bodies If the foreign body rotates about the same axis and through the same angle as the eye, it is certainly in the eyeball, or in a part of the muscle. If the displacement is not a rotation about the same axis, a careful study will show if it is in the soft parts or in a muscle, and ultimately in which muscle it is situated. For the production of the lateral radiographs, it is desirable to use a small table with a tunnel, so that the plates can be easily changed while the head is kept immobilised; quite small plates will suffice, say 9 by 12 cm. Across the opening under which the plate slides a fine wire is placed. The head is adjusted on /n /roni. /breijf/i /body . Illustration 16. This illustration shows the relative positions of the eye and the plate in the production of the lateral radiographs. The axes are also shown. a.p., the wire over the plate. Ao-Po, the corresponding axis. the tunnel in such a manner that the metal wire is parallel to an imaginary line passing through the centre of the cornea and back through the central axis of the eye, while the patient gazes to the horizon, and that the shadow of the wire on the plates coincides with this line; thus the horizontal equator of the eye is materialised. (Illustration 15,) The tube should be centered above at a sufficient distance to ensure that the resulting radiograph of the globe may be X-Rav Observations for Foreign Bodies 29 considered an orthogonal projection. Froma platesoobtained, measurements may be considered actual (for the lateraB radiograph, 80 cm. from a,nticathode to plate gives a maximum error of i mm.; for the antero-posterior, 65 cm. gives the same error). The normal ray should pass through the central axis of the eye, and at right angles to the plate. With the patient, tube, and plate so arranged, three radio- graphs are now made with the head immobilised; in the first plate (to be marked "0") the patient's gaze is directed to the horizon, in the second it is directed upwards, and in the third downwards, and the plates are marked accordingly. Illustration 17. The relative positions of the eye and the plate are here shown for the production of the antero-posterior radiographs. ie and bb The cross wires in front of the eye and their corresponding axes are shown. For the antero-posterior radiographs two fine cross wires are required, and while the patient gazes to the horizon (or in this case vertically up to the ceiling), the frame carrying, the cross wires is adjusted so that the intersection shall be vertically over the centre of the cornea, and the wires coincide with the horizontal and vertical equators of the eye ; on these the plate is placed. The tube must now be centered so that the normal ray shall pass through the intersection of the cross wires. With the patient so disposed, and tube and plate arranged, the first plate is exposed, and for the second exposure the patient is directed to gaze to the side opposite to that of the injured eye (adduction). Five plates have now 30 X-Ray Observations for Foreign Bodies been taken, and from the study of these the diagnosis will be made. (Illustrations i6, 17.) The first step towards localisation is to make tracings from the radiographs — from each set one composite tracing is made. From plate " " the outHnes of the bony skeleton of the orbit and of the metal wire are drawn on transparent paper. The foreign body is also traced; this should be done accu- rately, with attention to any orientation it may possess; then carefully superimposing the tracings on the plates marked " up " and " down," the other shadows of the foreign body are added. The same procedure is followed in the production of the antero-posterior tracing. These tracings may be called '• lateral" and "frontal." (Illustrations 18, 19.) Illustration 18. Lateral Tracing. Illustration 19. Frontal Tracing. It is possible that the shadows of the foreign body may completely overlie; they may overlie in one tracing and be neatly separated in the other; or they may be separated in both. A foreign body that has not moved in either is (ci) not in the eye at all, or {b) in the centre of the eye; this latter possi- bility is important and must never be overlooked; it may mean a tiny foreign body located in the vitreous humour, or adhering to the posterior surface of the crystalline lens. If the foreign body is in the centre of the globe, its position in the lateral tracing will be slightly anterior to the shadow of the malar border of the orbit, and near also to the shadow of the wire that materialises the horizontal axis of the eye ; and on the X-Ray Observations for Foreign Bodies 31 frontal tracing it will coincide, or nearly so, with the centre of the cross wires. This question will only arise when the foreign body is very tiny and spherical in shape, otherwise it will be possible to follow its orientations in the changes of position. Where the foreign body is on one of the axes of rotation, but not central, the shadow will have moved in one of the two tracings. (Illustration 20.) Fig. I. i. \ Fig. 2. Illustration 20. Foreign Body situated on the Horizontal Axis of the Eye. Fig. I. A horizontal section cut at the level of the centre of the eye when the eye looks to the horizon. Fig. 2. Frontal tracing from two radiographs, between which the eye has moved in adduction ; the tracing shows the movement of the foreign body in such a case. Foreign body R in the temporal hemisphere during adduction moves for- ward from the position Ro to the position Rl, that is to say it is dis- placed towards the centre. Foreign body S, in the nasal hemisphere, is carried back towards the centre. In the case in which the foreign body has moved and pro- duced the three successive shadows on the lateral tracing, the process is as follows. Two fine lines are drawn connecting the three shadows (using the same point of oriental ion of the foreign body), and from the centres of these lines two perpen- diculars are drawn; their intersection forms the centre of a circte passing through the three positions of the foreign body 32 X-Ray Observations for Foreign Bodies (see Illustration 21). In this manner the centre of the globe is materialised. If this point falls just anterior to the malar border of the orbit, the foreign body is in the globe, and its position can be given in two directions, and the third obtained from the frontal tracing. If the intersection falls remote from the malar border, and from the horizontal plane projection^ the foreign body is not in the globe but in one of the muscles, (See Illustrations 22-25.) Illustration 21. The geometrical construction on the lateral tracing foreign body in the eye. Inferior posterior quarter. To ascertain if the movement of the foreign body corre- sponds to the rotation of the eye, a long ruler, fitted with a movable electric lamp, is placed at a known distance from the patient and used to direct his gaze, and the displacements above and below the central or horizontal position are recorded. With this information (using cm. to represent metres) the angle the eve has turned through can be reconstructed on the lateral X-Ray Observations for Foreign Bodies 33 tracing, showing definitely whether the foreign body has turned ithrough the same angle. (Illustrations 15, 26-27-31.) In those tracings which show that the foreign body has smoved, and yet the centre of the circle on which the shadows Illustration 22. Lateral Tracing. Foreign body in the superior rectus. Fig. I. The elevation of the eye produced by the contraction of the superior rectus muscle causes the foreign body to be pulled nearer to the fixed insertion of the muscle (Shadow I). When the eye is lowered the reverse takes place. The superior rectus is lengthened, displacing the shadow of the foreign body to the opposite side (shadow 2) of the zero position ■(shadow 0) which is the shadow formed when the patient gazed to the horizon. The Frontal Tracing. Fig. 2. The movement of adduction ^has hardly moved the foreign body; the two shadows overlie. Illustration 23. Foreign Body in the inferior rectus. Lateral Tracing. Fig. I. In this case thelowering of the eye produced by the con- traction of the inferior rectus draws the foreign body nearer to its fixed insertion (shadow 2), while the elevation of the eye by the contraction of the superior rectus lengthens the inferior and again displaces the foreign body to the opposite side (shadow I) of zero. Frontal Tracing. Fig. 2. No movement is shown in the frontal radiograph; the shadows overlie. 34- X-Ray Observations for Foreign Bodies lie does not occur at the point indicated as the centre of the globe, a little study will reveal the actual position of the foreign body ; bearing in mind the muscles that produced the move- ments of the eye recorded on the plates, interpretation i& comparatively simple. (Illustrations 22-25.) Position of Patient. In all methods of localisation, with one mark on the skin below which at a measured distance in the vertical line a foreign body is situated, all the general information of the. Illustration 24. Lateral tracing with the geometrical construction showing a foreign- body moving with the eye but not in the globe. The centre of rotation K is shown to be some distance away from the position known to be the centre of the eye. previous examination should be studied. The patient should,, if possible, be placed for the more exact localisation in sucb a position that, when he is operated upon, a vertical incision can be made through the localisation mark. If no satisfactory previous information is at hand, rough observations should' be made, for it will frequently occur that the foreign body i& not nearest to the surface at the point indicated, or important structures may intervene making it undesirable to operate through this point. It is, therefore, necessary to consider the position of the foreign body, and the best means of approach,, and localise it with the patient so placed. It matters little if the incision has to be carried a little deeper along the localisa- X-Ray Observations for Foreign Bodies 35 tion line, for one is fairly sure to strike the foreign body. But careful judgment is necessary to enter laterally for a foreign body localised in this manner, and the operation is often unsuccessful, the slightest deviation resulting in failure. Fig. I. Fig. 2. Illustration 25. Foreign Bodies in the Internal and External Rectus. Fig. I. Horizontal cross section at the level of the internal and external rectus.. A. P. shows the antero-posterior axis. Fig. 2. Frontal tracing (composite) showing the shadows of the foreign body produced by the movements of the eye. Ro foreign body in the external rectus. Plate taken with the patient gazing to the horizon gives the shadow 0, formed by the foreign body when at Ro. On adducting the eye the external rectus is lengthened and the foreign body moves to Rl, placing the shadow on the radiograph at I, that is to say outward displacement. So foreign body in the internal rectus. Plate taken with the patient gazing to the horizon gives the shadow O' formed by the foreign body when at So. The second radiograph taken with the eye in adduction produced by the contraction of the internal rectus draws the foreign body nearer to the fixed insertion of the muscle Si, giving the shadow l'. AnatoxMical Localisation. While geometrical localisations are absolutely necessary^ much more information is desirable to ensure the successful 36 X-Ray Observations for Foreign Bodies removal of foreign bodies. It is never easy, in fact, rarely possible, to state the exact position of a projectile from flat plates. Antero-posterior and lateral radiographs at right angle planes and of the same projection are useful, and, at times, desirable, but they are a poor substitute for stereoscopic plates. From the latter the most valuable information can be obtained. In the limbs, rotation and observations from several aspects may demonstrate whether the foreign body is in soft tissues or embedded in bone; but at an articulation, tarsus, carpus, shoulder, or vertebrae, every available device, manipulation, and the use of discriminating judgment will often be necessary Illustration'26. Reproduction of the angle of rotation of the eye on a milli- metre to the centimetre scale. Illustration 27. Geometrical construction of the angle of rotation of the eye. in order to come to a definite conclusion. Besides turning the limb or body, use should be made of the oblique rays, by long displacement of the tube, in the hope of being able to throw the shadow free from bony structures. It is even more difficult to decide the location of a foreign body in the thorax, abdomen, or pelvis. A projectile in the lung may move with respiration or not, depending upon its location ; at the root there would be little if any movement, while at the base the excursion may be considerable. How- ever, it must not be forgotten that a foreign body may be pre- vented from moving and yet be in a lung restricted by adhesions. X-Ray Observations for Foreign Bodies 37 On the other hand, the moving shadow of the ribs may impart to the foreign body an apparent movement it does not possess. Further, the presence of air or fluid in the pleural cavity will complicate matters, and with a projectile fairly superficial in the lung it may be impossible to make a definite statement in a few cases. Frequently, an abscess forms about the foreign body, and later a cavity containing air, fluid, or Illustration 28. Dotted line of the diaphragm, normal respiration— dotted foreign body- in the liver shadow : dark line of diaphragm, forced inspiration — dark foreign body projected above liver region. both, and the projectile may be shown to be free in some cases by changing the position of the patient and allowing some time to elapse between observations. Not infrequently, a projectile may be near or attached to a large vessel, and a " kick " may be observed imparted by the 38 X-Ray Observations for Foreign Bodies pulsation, or such a movement may be communicated by the heart; in this latter case, the excursion of the foreign body will be greater, and may be seen to occur in the mediastinum and over a large area of the left lung, but may be somewfiat modified if the lung is partially collapsed or consolidated in the vicinity. Illustration 29. The circles indicate the positions of the X-ray tube with the corresponding projections on the screen when examining the region of the diaphragm. These cases should all be submitted to thorough general observation, and all conditions noted and recorded with the localisation. Some help can be obtained by applying a small metal ring to the chest wall and observing the behaviour of the X-Ray Observations for Foreign Bodies 39 foreign body in relation to this shadow. If the foreign body rises with inspiration and remains fixed in its relation to the ribs, it is most probably in or attached to the chest wall. Attention to every detail is imperative, and statements should be made with the greatest caution, for upon these findings important and responsible decisions are to be made. To decide the location of a projectile in the region of the diaphragm is particularly difficult. Forced inspiration will often show a foreign body to be above the diaphragm, when its shadow was projected well within the liver area with normal respiration (Illustration 28). The patient should be observed from every position. To search the posterior inferior portion of the chest the tube should be lowered posterior to the level of the fourth lumbar vertebra, when, by the oblique ray, the shadow may be thrown well above the diaphragm, settling all doubt as to its position. If this is not successful the position should be reversed. (Illustration 29.) It is often impossible to give definitely the position of foreign bodies in the abdomen. They may move freely from time to time. For this reason observation on fresh cases should be made within a few hours of operation. Further- more, it is not an unusual occurrence for a foreign body to be passed by the rectum, and should this occur a patient might be submitted to a needless operation. In cases where special difficulty exists, or an anatomical localisation is uncertain, preparation should be made at the time of operation for intermittent control by the fluorescent screen. Stereoscopic Localisation.* Undoubtedly, good stereoscopic plates give more informa- tion than antero-posterior and lateral plates, and in difficult cases they should always be taken, particularly if one of the stereoscopes for viewing and measuring the depth of the foreign body by a mechanical attachment is at hand, such as * " La Radiostereoscopie en Chirurgie de Guerre," Juiiv. dc Raaiol. cf cfEL, March, 1916. "La Localisation Anatomique des Projectilespar la Radiographic Stereo- scopique." Loccit. 40 X-Ray Observations for Foreign Bodies the Maze Radiostereometer* (Illustration 30), or the stereo- thesmetre of Paris Richard. To this apparatus is fixed la. small handle that controls the passage of a measure, and indicates on a dial the depth of the foreign body. The- relation of the foreign body can also be determined to any Illustration 30. Stereoscope for measuring the depth of foreign bodies. C — X-ray plate,. j^ — Movable register, G- -Mirror bisector. On the front is the dial that indicates in millimetres the depth of the foreign body. other structure shown on the plate. The calculations in this- case are based on a distance from tube to plate of 50 cm. The first exposure is made from the central position, and the second with a lateral displacement of 4 cm,, which measure- * Arch. d'ElcdricUc Med., Oct., 1917. X-Ray Observations for Foreign Bodies 41 ment must be rigorously adhered to. The most portable and convenient form of stereoscope is the Binocular or Pierre form, or the Hirtz Mirror bisector type. A simple appliance on this principle, devised by the author,* makes it possible to exercise considerable economy in stereo-radiography of the limbs, and no complicatedapparatus- is required for viewing. A small metallic badge may be used Illustration 31. Stereoscopic realisation with a simple mirror. to mark the sinus or wound, and a letter (the same one as that used for the purpose of marking " left " or "right") should be placed upon the anterior surface of the liinb. A plate is now taken, half of which is placed under the limb' in the usual position, with the film towards the tube, the other * "Stereoscopic Radiography of the Limbs," Arcli. Radiol.'aiid Electro- therapy, June, 1917; B.M.J., Sept. 29th, 1917. 42 X-Ray Observations for Foreign Bodies half of the plate being covered by sheet lead. The tube is -centered over the limb, and afterwards displaced 3 cm. laterally. After the first exposure the plate is carefully withdrawn without disturbing the limb, and the unexposed half of the plate inserted, this time with the glass side towards the tube. The second exposure is then made after the tube has been again displaced 3 cm. on the opposite side of the centre. It will be found that the best stereoscopic results will be obtained by increasing the displacement for a thin limb, like forearm or hand, to as much as 4 cm. on either side of the centre ; while for the thigh the displacement should be diminished. The height of the tube has also some influence upon the stereoscopic effect ; the closer the tube is to the plate, the less displacement is required. To view these plates when so taken, all that is required is two mirrors, some 20 cm. by 25 cm. in size, placed back to back, and bound for convenience with a piece of adhesive tape (Illustration 31). The whole of the plate must be equally illuminated. The mirror should be placed in the centre of the two pictures, and the observer should close an eye until he sees one picture clearly reflected. When both eyes are open a stereoscopic projection is obtained. The position of the sinus (marked by the metal disc) becomes evident ; and sequestra or foreign bodies, which might appear as one in an ordinary radiograph, will now stand out in relief, and can be enumejated, and accounted for at the subsequent operation. (Plate i.) Should the letter placed anteriorly appear on the side oppo- site to the observer, he is viewing the posterior aspect ; to obtain the anterior aspect, he must incline the head to the opposite side and use the other mirror. Cross Section Localisation by Three Intersecting Lines.* The old method of localisation by two intersecting lines was not exact, and the method and technique to be described has been developed and perfected by the author. It is un- " Belot et Fraudet, Jour, dc Radiol, et d'Ekcli other., Jan., 1916. J. M. Flint, Ann. Surg., Aug., 1916. H. C. Gage, Aicli. Radiol, and Elccirollicr., June, 1917. A typical stereo-radiograph which if viewed with a mirror will immediately illustrate the advantages of the method described. (The sinus in this case is marked with a pin.) Plate I. 44 X-Kav Observations for Foreign Bodies doubtedly the one of choice where the foreign body can be- seen on the screen. It is independent, as will be seen, of any mathematical calculations, it is accurate, and the results are self-proving, for the chart, when complete, discloses at once if the observations have been made correctly or not. The method in itself comorises geometrical and anatomical localisation 3. 0. Q Illustration 32, Localising appliances. combined with mechanical guidance. The appliances neces- sary are very simple, and can, should the situation demand it, be home made. (Illustration 32.) Two pairs of compasses are shaped as illustrated in Figs. I and 2. Two sizes are necessary, as it is desirable that the X-Ray Observations for Foreign Bodies 45 rings shall be parallel when in use; a large pair (for the body) about 35 cm. long, a second pair (for the limbs) about 12' 5 cm. The rings in each case can be made to enclose smaller rings to facilitate the centering of a tiny foreign body (Figs, i :and 2, b, c, and d). The body compasses are further improved by jointing the last 6 or 7 cm. of the arms by means of a small bolt and thumb screw. (Fig. la.) With this additional adjustment the rings can be placed in contact with the body in any position. Illustration 33. Antero-posterior observation. In the first method the compasses are used in the following manner. The patient is first placed, if a horizontal table be used, upon his back. Long sandbags may be laid under the patient on either side of the area of localisation, in order to permit the insertion of the compasses beneath the limb or body. Other sandbags may be adjusted for the comfort of the patient. (Illustration 33.) Should a table with sliding cross panels be 46 X-Ray Observations for Foreign Bodies in use, one of these panels may be removed to provide con- venient access. Observations in the antero-posterior position are made, adjusting the compasses in such a manner that the foreign body appears on the screen encircled by the rings. (Illustration 34, Figs, i and 2.) The skin is marked through these rings with blue grease paint and the patient then rotated. In this rotation great care should be taken, for the accuracy of Q (0) Illustration 34. Diagrammatic Application of Compass, Diaphragm and Arc. Fig. I. a, b. Normal ray; c, d, e, f. Oblique rays; g. Diaphragm with tubes ; /'. Closed diaphragm ; /. Open diaphragm ; /. X-ray tube ; k. Table ; /.Foreign body; "/.Compass; ». Additional hinges; 0. Principal hinge; p. Patient. Fig. 2. I. Well centred; 2. Badly centred foreign body. Fig. 3. Arc (for use at operation) ; I and 3. Probes (in position on localisation marks on skin) ; 2. Measured probe (in position on foreign body) ; 4. Nut ; 5. Thumb-screw. localisation depends upon the turningof the limb or the body, as one would turn a cylinder, so as to avoid change of contour of the surface anatomy. If such a change takes place a false relationship between the foreign body, and the superficial markings on the skin will result. With a little care, however, and in the case of the body, a vertical screening stand, this difficulty will not occur. Having successfully turned the X-Ray Observations for Foreign Bodies 47 patient, the foreign body is again encircled with the rings of the compass and further skin markings made with grease paint of another colour. This marking is then repeated in a third position, making three observations in all, and giving six marks of three colours upon the skin. Production of the Outline Contour. Reference should now be made to Illustration 32, Fig. 5, 5,-. .T *Oo^ '^4 <;%'^;»o;;*