August 19, 1909] 



NA TURE 



221 



take advantage of the useful properties of the Rontgen 

 ravs, and, indeed, the physicians commenced the use 

 of" this method of diagnosis very early, since it was 

 found that the heart and aorta cast a fairly distinct 

 shadow. Before long it was shown that certain dis- 

 eases of the lungs were also recognisable, and still 

 later some of the other organs, notably the kidneys 

 and the liver, were added to the list of organs which 

 were accessible to Rontgen-ray diagnosis. At the 

 present time, not only these various organs, but the 

 entire length of the alimentary canal can be revealed 

 and explored. Opacity to Rontgen rays is almost en- 

 tirely a function of density. Of the substances which 

 enter into the construction of the human frame, the 

 least dense is air. The healthy lungs have their 

 spongy tissue filled with air, and they are, therefore, 

 the most transradiant organs of the body. The lungs 

 are contained in the thin-walled chest, so that there 

 is very little substance to interfere with their trans- 

 radiancy. In examining the chest upon the fluorescent 

 screen, it is seen that "the act of deep inspiration in- 

 creases the transradiancv of the lungs, the shadows 

 cast by the ribs being shown up in greater contrast 

 tlian during expiration. This is exactly what would 

 be expected, since the spongy tissue of the lungs 

 becomes blown up and filled with air during the act 

 of inspiration. The heart and aorta are far denser 

 organs, and thev are shown up in strong relief against 

 the background of the air-containing lungs. It is, 

 therefore, quite easy to estimate the size, shape, and 

 position of the heart and aorta. 



It must be remembered that the shadow cast upon 

 tlie fluorescent screen (or obtained by photography 

 upon a photographic plate) is greater than the actual 

 size of the organ. For some purposes it is important 

 to obtain an accurate measure of the true size of the 

 heart. In this case the X-ray tube— which nowadays 

 is alwavs enclosed in an opaque box or shield — is so 

 arranged that there is only a small opening through 

 which the X-rays can emerge and penetrate the 

 patient's body. The apparatus is arranged so that 

 the X-ray tube can be moved to any position in its 

 own plane. If the tube be moved around the margins 

 of the heart, and these margins be marked out upon 

 the glass which covers the front of the fluorescent 

 screen, an outline of the heart is obtained upon the 

 glass, and represents the true projection of the heart 

 in the plane of the fluorescent screen, and for prac- 

 tical purposes this may usually be regarded as repre- 

 senting the true size of the heart. The pulsations of 

 the heart and of the aorta can be studied minutely 

 upon the fluorescent screen. 



Coming now to the lungs, it will be clear that any 

 tumour or condensed area in the lungs will be shown 

 up in relief against the air-containing healthy lung 

 tissue. In this way the consolidation due to phthisis 

 is shown even in the earliest stages of the disease. 

 For instance, there may be slight diminution of trans- 

 radiancy near the apex'of one lung. On deep inspira- 

 tion the whole of the lung becomes more transradiant, 

 showing up the impaired apex in stronger contrast. 

 There are other signs observable on the fluorescent 

 screen in phthisis; thus the range of movement of 

 the diaphragm is much restricted. In more advanced 

 phthisis the congested areas are shown as dark 

 shadows, and in very advanced disease where there 

 are cavities in the lung these cavities are frequently 

 visible as lighter areas with irregular outlines sur- 

 rounded bv a darker area of congested lung. Other 

 diseases of the chest, tumours in the glands, cysts, 

 &c., are shown against the light background of the 

 healthy lungs. 



When there is fluid accumulated in the pleural 

 cavity, i.e. between the chest wall and the lungs, it 

 is necessary to examine the patient in the upright 

 NO. 2077, VOL. Si] 



position in order to obtain the effect of gravity in 

 causing the fluid to take up a position at the base 

 of the chest. Fluid in the chest is very opaque when 

 compared with the transradiancy of the lungs. When 

 fluid begins to collect in the chest it is found at the 

 most dependent part of the chest, where the diaphragm 

 is attached to the chest wall. As the fluid accumu- 

 lates, the opaque area increases upwards, its upper 

 limit forming a curved line concave upward, the 

 direction of which is from the middle line of the 

 body upward and outward. The greater the quantity 

 of fluid, the higher and the steeper does the position 

 of this line become, but with increasing accumula- 

 tion of fluid the lung itself, which is floated up upon 

 the fluid, becomes more and more compressed, and, 

 therefore, less and less transradiant, so that the line 

 which separates the liquid from the lung becomes 

 more and more ill-defined, and finally disappears 

 altogether, the whole of this half of the chest be- 

 coming uniformly opaque, since the lung- itself has 

 become so greatly compressed that it no longer con- 

 tains any appreciable quantity of air. As the fluid 

 accumulates, it is observed that the heart becomes 

 displaced further and further to the opposite side of 

 the chest. 



The foregoing description refers to cases in which 

 there is an accumulation of liquid only, but in other 

 cases (known as hydropneumothorax) not only is there 

 a collection of liquid in the pleural cavity, but there 

 is also free air in this cavity. In this case the appear- 

 ances are fundamentally altered, for there is now a 

 sharply-defined horizontal line of demarcation between 

 the liquid and the air. The lung itself is collapsed, 

 and usuallv occupies a small space close against the 

 middle line of the body. The heart is displaced to 

 the opposite side of the chest. W'e have here the 

 phvsical conditions of a liquid contained in a vessel 

 and placed in air. On tilting the patient, the liquid 

 is at once seen to flow in a direction which enables 

 its upper surface again to become horizontal. If the 

 movements of the patient are fairly rapid, waves are 

 produced in the liquid, and this is still better seen if 

 the patient shake himself or be shaken. It frequently 

 happens that the heart beats against the liquid and 

 sends a regular series of waves along the surface of 

 the liquid. Hitherto, in forming their opinion as to 

 the nature of diseases of the chest, physicians have 

 been dependent upon the information derived from the 

 application of percussion and auscultation, and 

 although very accurate information can in many cases 

 be obtained by these methods, a Rontgen-ray examina- 

 tion is still of great importance in confirming the 

 conclusions obtained from the other clinical methods 

 of examination, and in supplementing information 

 thus obtained. Thus in phthisis the degree and 

 extent of the affected lung is shown with far greater 

 accuracy by the Rontgen-ray method than by the 

 methods of percussion and auscultation, and in many 

 cases pulmonary lesions which are quite unrecog- 

 nisable by percussion and auscultation may be clearly 

 shown upon the fluorescent screen. In other cases 

 the Rontgen-ray examination leads to a diagnosis 

 entirely different from that obtained by percussion and 

 auscultation. 



In the examination of the abdomen, the conditions 

 are very different from those which prevail in the 

 case of' the chest. There is usually no air in the 

 abdominal cavity except such as may be contained in 

 the stomach or 'in the large intestine. Consequently, 

 the only structures which stand out in strong relief 

 are the bones, viz. those of the vertebral column, the 

 hip bones, and the lower ribs. There is a way, how- 

 ever, in which the conditions in the abdomen may 

 be made more to resemble those found in the chest. 

 Air may be forced into the large intestine, and its 



