THE LIMITATIONS IN MANIFESTING X-RAY GRAM

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  • X線写真像示現の限界
  • Xセン シャシンゾウ ジゲン ノ ゲンカイ

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The limitation in manifesting X-ray gram is influenced by an apparatus, X-ray tube, fittings and sensitizer, all of which have been improved. According to these improvements, the limitations in manifesting X-ray gram has been reduced. Therefore the author tried to find the limitations, using usual apparatus, fittings and sensitizer. In general, contrast, sharpness and density are the important factors in manifesting X-ray gram. Regarding contrast at the detailed manifesting, that is, contrast in detail, in order to study the delicate diference of density and the manifestation of a very small object, the author examined the position of the object (M.P.D.) surrounded by other substances which are a cause of scattering X-ray, the size of the object and the degree of X-ray absorption and the following points were concluded. 1) The more the X-ray absorption is, and the bigger the object is, the larger the M.P.D. becomes to reduce the relative contrast. In those experiments each limits were found in every change of doses of abosrbed X-ray, the size of object and M.P.D. 2) When the scattering X-ray was eliminated, the more the X-ray absorption is, and the bigger the object is, the relative contrast was increased. The phenomena was caused by the fact that X-ray quantity and condition of scattering X-ray are influenced by the object and surrounding substances. The same phenomena were found in radiography with opaque medium in which the X-ray absorption is more than in the usual rediography. The method for manifesting the part whose density is low as mentioned above was studied in theory. Standing on the results obtained from the theoritical study, the author made fundamental experiments, using a phantom in angiography, ventriculography, cholecystography, cystography and nephrography, all of which are hard to show a clear contrast, or whose objects are very small and slender. These fundamental experiments were applied in clinic. Taking up the object like beam-borne and crack in borne, the unsharpness caused by form of object and sensitizer was studied and unsharpness caused by momement of object was studied in angiocrardiography. The degree of unsharpness controlled by the size of focus and M.P.D., tube voltage, scattering X-ray, the exposure time-all of which have influence on sharpness-were exaimned and each limits in every change was tested out. In order to interpretate the detailed X-ray gram, a scientific and objective way of observing was abovocated here, considering the light quantitty, reflected light from the outside and psychlogical influence.

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