. The American journal of roentgenology, radium therapy and nuclear medicine . ative is just as brilliant as if the correctexposure had been given. No graininess atall is produced in cases of overexposure as is the case when intensifying screens areemployed. With regard to contrast in such a subjectas the pelvic region and in regard to detailand brilliancy of the image, the Impex platecompares very favorably with the ordinaryplates at present in use. Another advantage,which is directly due to the very short ex-posure required, is the superior sharpness ofoutline obtained owing to the relative
. The American journal of roentgenology, radium therapy and nuclear medicine . ative is just as brilliant as if the correctexposure had been given. No graininess atall is produced in cases of overexposure as is the case when intensifying screens areemployed. With regard to contrast in such a subjectas the pelvic region and in regard to detailand brilliancy of the image, the Impex platecompares very favorably with the ordinaryplates at present in use. Another advantage,which is directly due to the very short ex-posure required, is the superior sharpness ofoutline obtained owing to the relative immo-bility of the patient, who is capable of keep-ing perfectly still for the very short ex-posure required with the new plate, but whocannot possibly do so for a much more pro-longed period. C. Gradation and Range.—It is generallyrecognized in radiography that the shorterwave-lengths—as emitted by a hard tube—give less contrast and conversely the nega-tive obtained with a soft tube is more bril-liant, provided the penetration is adequatefor the subject Fig. 4. Radiograph of knee taken on Impex plate. The scale of gradation obtainal:)le with an-t-ray plate of the ordinary tvpe is thereforestrongly selective. The technique of theImpex plate is. however, entirely rays excite a far more powerful fluor- Radiographic Exposures Reduced by Impex Plate 533 escence in the Impex layer and the tubeshould always be worked in a hard condi-tion—preferably about 7 inch equivalentspark-gap or more. This method of working does not destroydefinition in the very soft tissues, for which very hard rays, and these are the conditionsin which the maximum reduction of e:5^os-ure, coupled with the greatest detail andcontrast, are obtained. This point requiresspecial emphasis, as in certain cases wherethe maximum reduction of speed was not
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