Fig. 4.—1. Male patient, aged ten years. Temporary incisors in position with the permanent incisors nearly ready to erupt. The roots of the temporary teeth nearly absorbed. Right temporary central cut incisor destroyed by a blow five years previous, showing gutta-percha filling put in at the time which, with the dead root, has been absorbed (same as the live root of the other central). It is taught in the text-books that teeth with dead nerves are not absorbed. 2. Temporary molars in position with no signs of the permanent bicuspid which should take its place. 3. Patient, aged ten years. Shows the open ends of the incisor roots. 4. Shows one bicuspid and two molar teeth. The roots of the teeth pass through the floor of and into the cavity of the antrum. The spongy character of the bone is shown. 5 and 6. Superior jaw, right and left sides, showing temporary cuspid teeth in place, with the permanent cuspids imbedded in the jaw entirely covered.
The use of photographic films in the application of the X rays in surgery will doubtless extend; we can easily imagine cases where the necessity of the use of the knife may be avoided by the information which a carefully placed film might afford. In general, X-ray photographs convey more information to the skilled eye of the specialist than to the untrained inspector of them. They should be studied from the negatives themselves, for the delicate details can not be reproduced in a print. It is remarkable that shadow pictures can show so much definition. Here is a photograph of an elbow joint which shows the texture of the bones ([Fig. 5]).[E]
[E] Taken by Professor Goodspeed, University of Pennsylvania.
The use of the fluorescent screen, too, has been greatly extended. Dr. Francis H. Williams, of Boston, has used it as a valuable instrument in medical diagnosis, especially in studying lung diseases. It has been used at the Harvard Medical School to follow the processes of digestion. To accomplish this, in one instance a goose was fed with food mixed with subnitrate of bismuth, a salt which absorbs X rays.
Fig. 5.—Photograph of an elbow joint, showing the texture of the bones.
The passage of the dark mass down the long neck of the bird could be traced on the fluorescent screen, and the peculiarities of its motion in the gullet could be studied. A cat was also fed with the same substance, and the movements of its stomach noted. These movements were analogous to those of the heart—in other words, were rhythmical when the processes of digestion were going on normally and uninterruptedly. When, however, the cat was irritated, it may be by the sight of a dog, these pulsations instantly ceased. As soon as the source of vexation was removed and the purring of the animal showed a contented frame of mind, the stomach resumed its rhythmical movements. The dependence of the digestive apparatus on the state of the nervous system was thus clearly shown. The female cat was much more tractable under these experiments than the male.
The use of the X rays is accompanied with some danger if the Crooke’s tube is not properly used. A long exposure to the X rays is apt to produce bad burns which are like sunburns, and lead in certain cases to bad ulcerations. They are long in healing and are characterized by a peculiar red glow, especially on exposure to a cold wind. To prevent them one should place a sheet of thin aluminum between the Crooke’s tube and the part of the body submitted to the rays. This sheet should be connected to the earth. This fact should be borne in mind when we come to speak of the electrical region outside a Crooke’s tube.
Many investigators, reflecting upon the singular fact that the rays pass so freely through thin aluminum and that, on the contrary, glass absorbs such a large percentage, concluded that Crooke’s tubes provided with aluminum windows would be an improvement upon the thin incandescent lamplike bulbs now used. The glass of these bulbs is very thin, not more than one thousandth of an inch in thickness, where the rays emerge, not thicker than a sheet of ordinary note paper, and the absorption of such a sheet of glass is so small that it can not be detected by photography. Thus a sliver of glass of this thickness in the hand would not appear on the X-ray photograph of this member, and would not cast a shadow in the fluoroscope. There does not seem, therefore, any advantage in supplying a Crooke’s tube with an aluminum window. The mechanical difficulties, too, in accomplishing this are very great. There is no way of joining the thin aluminum disk to the glass so that an air-tight joint can be made. In the process of exhausting the Crooke’s tube, the tube must be heated to a comparatively high temperature in order to drive off the air which clings to the inside of the glass. The rise of temperature would soften or melt any current which might be used to make the aluminum adhere to the glass.
We can not expect, therefore, any improvement in the direction of aluminum windows. At one time, I suppose that the rays were highly absorbed in passing through atmospheric air, and that it would be an improvement in the application of the rays to surgery to interpose, so to speak, a vacuum chamber between the body and the source of the X rays. The experiment led to some interesting results, but not in the direction anticipated.