THE ADJUSTABLE TOMOGRAPHY

Abstract

The tomography in which the X-ray tube and film were moved to the direction of the central X-ray and the ratio of the distance between the focus and the aimed plane to that between the aimed pland and the film was kept constant during the exposure, was named "adjustable tomography" temporarily. This method of roentgenography was theoretically studied and the results were as follows. 1) If the ratio of the moving distance of the X-ray tube to the maximum distance between the focus and the aimed plane was named the "moving rate" and represented by n, the product of the output of the X-ray tube and the exposure needed for this tomography would be (1-n) times of that needed for the roentgenography in the fixed position where the distance between the tube and the film was maximum. 2) To obtain the best pictures from the viewpoint of dimness of the aimed plane and aberration of the unaimed planes, the film and the X-ray tube were to be moved as close as possible to the object until the former restricted by it and the latter was limited by the magnifying power which was decided by the size of the focus, and the moving rate was to be kept at about 0.5.