Presentation of the Radiograph

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Abstract
It is probably fair to say that every radiologist has at some time been dissatisfied with the way in which his work has been reproduced, and that radiographs generally are among the worst illustrations in medical literature. There are reasons for this, but there are also methods whereby the situation may be improved. The radiographer strives to obtain the triad of contrast, detail and definition; to assist him the manufacturer has given him many things, but especially double-coated film. The resulting radiographs may have a density range up to 3 or even higher, and for such dense areas of film the “local bright light” is in daily use in every diagnostic department. A chart, Fig. 1 (after Thorpe and Davison, 1944), translates absolute values into terms of ordinary viewing conditions. The step-wedge is somewhat approximate; the ranges of normal and of high-intensity viewing are shown. This high density range renders the radiograph more difficult to copy or print than an ordinary negative, for all available positive materials have a considerably restricted exposure range (which is, of course, equivalent to the density range of the original radiograph, since the light passing through this constitutes the printing exposure). A radiograph may be reproduced either as a positive, in which the tone values of the original film are reversed, or as a “facsimile”, in which the tone values are in the same sense as the original.1

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