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There is no difficulty in obtaining a xeroradiograph of a thin part of the body such as the hand. Over a comparatively wide range of charge and development time the picture is immediately recognisable even though the appearance of the plate as viewed by reflected light is quite different from that of an ordinary radiograph. Careful comparison of the results with the radiograph shows that bone detail readily visible in the latter is not always visible on the xeroradiograph. Rather unexpectedly soft tissue frequently shows clearly and with greater contrast on the xeroradiograph than on a radiograph. Relative to film the xerographic plate is slow and requires significantly greater exposures. Any assessment of the present possibilities and the most fruitful line of future development of the process is necessarily contingent upon a careful comparison between it and the conventional film techniques.Present knowledge indicates that there are three variables to be considered, viz. (i) the time for which the plate is charged; (ii) the X-ray exposure; and (iii) the time for which the exposed plate is subjected to the powder cloud. The effects of changes in these have been studied, bone (a metacarpal) being used as a phantom. Precautions were taken to ensure precise positioning of the phantom with respect to xerographic plate and the X-ray tube. As the work involved taking many pictures each of these was recorderd photographically so that comparison could be mde without having to use large numbers of plates.

A simple method of evaluating the suitability of X-ray apparatus for coronary arteriography, which was devised to develop a technique using 70 mm film and videotape is described. Selected coronary arteriograms obtained by this method are presented.

From the earliest days of radiology the reduction of the amount of scattered radiation reaching the film has engaged the attention of both radiologists and apparatus manufacturers. The interposition of a grid between patient and film has been the device most widely used for this purpose, and much effort has been devoted to the improvement of grids both in design and manufacture. Nevertheless, despite the pleas made at intervals in the radiological literature for the introduction of a method of specifying the performance of a grid in terms of its ultimate effect upon the radiograph, it is still customary to define the grid simply in terms of its “ratio”, the number of lines to the inch, and, where appropriate, the radius. In practice differences in film quality are frequently caused by differences between grids that are nominally the same as judged by these parameters. The evidence available suggests that only a grid of exceptional quality, whose stated ratio would be about 10 : 1, would be suitable for use over the wide range of kilovoltage say, 60 to 120, now being used. Because of the difficulty in selecting such a grid a high ratio grid is frequently used for all work regardless of the kilovoltage. In most cases such grids absorb a higher proportion of the image-forming radiation than do low ratio grids.