X-RAY INVENTION

Greymouth Evening Star, 26 May 1938, Page 7

X-RAY INVENTION

"SEES ROUND CORNERS," What, is probably one of the most important developments in X-rays in recent years was shown to specialists ally concealed by overlying structures, in London recently, says the "Sunday Express.” It is a dis'-overy which makes possible X-ray photographs which could never bo taken before. These photographs show parts of the body which have always been concealed or partioly concealed by overlying stdnetures. The inb.truinent is called a tomograph. and this is the fascinating story of how its works: — When an X-ray photograph is taken it shows the internal construction of ibody. but i; shows ail th - ■•n-ress-;u! layers superimposed e-;.- the crnei. if is ol'en impossible •■■m em-h pa.; clearly. li. is easy to see all tin' structures in an X-ray of the hand, for instance, but sometimes very difficult to see clearly all the structures in an X-ray of the head and the lungs, and especially in diseased lungs. That has always been the radiologist's problem. And that problem the tomograph solves. i rho tomograph the X-ray tube is above the patient, the rays passing t ight, though his body op to the photographic plato underneath him. _ Instead of being stationary the X-ray beam moves. It moves'in just the way it. could move if it were on the edge of a'big wheel, of which the hub was exactly in the fart of the body the specialist wants to see. The plate under the patient also moves, but. in the opposite direction. Suppose an X-day exposure lasts five seconds. The ray will be passing through the centre of the imaginary wheel for the whole five seconds, because whatever the position of a wheel in motion its centre is static,nThat means that the point selected by the specialist will be photographed. But. all the other parts of the body' around this point are not the. centre of the wheel. Tho X-ray only passes through them for a fraction oi the time, one after another. The result is exactly the same as when a. photographer is giving a. time exposure of a street in the evening. 'I tie street, comes out, but passers-by who just. HU. in front of the camera for a second do not come out. So in the tomograph, only the part at. the stationary' point of the moving ray comes out and the other parts of the body' just “flit by." On the plate they' are just a blur. The tomograph, in short, enables the X-ray to “see round the. corners.” The X-ray' tube can be focused on any given point in the body. ami intervening objects are faded out. Its possibilities for rhe good of mankind are immense. it is possible to photograph the centre, of the skull without the other parts. A “tomon striking thing to look at. It shows the spine clearly, while the ordinary X-ray shows it partly obscured by' the ribs. Delicate adjustments make it possible to take a picture at any “depth” of the body, inch by inch. It is even possible to photograph tho bronchial tubes in the lungs. 11. will make immensely easier the diagnosis of many diseases, among them cancer of the lung, tubercular cavities in the Inng, and spinal conditions. A tomographic apparatus costs about £lOOO, but attachment of the tomograph to existing apparatus costs considerably less.