Patent GB-564490-A (GB)
Abstract: 564,490. Stereoscopic radiography. DUDLEY, L. P. C. J., and MANSI, R. L. March 26, 1943, No. 4908. [Class 98 (i)] In a method of making stereo-radiographs, wherein a flat or curved Bucky grid is interposed between the body to be radiographed and the sensitive film or plate, and relative movement is produced, either during exposure or between two or more separate exposures, on the one hand between the body and the X-ray source to present different aspects of the body to the source, and on the other hand between the grid and the film or plate to record these aspects in interdigitated line fashion, the firstmentioned relative movement is produced by moving the body only, the ray-source remaining fixed, and the second-mentioned relative movement is equal to the width of one opaque strip of the grid. The grid strips are so disposed in the flat grid, or the curved grid is so curved, that the sides of the grid strips lie in planes which all pass through the ray source. Apparatus for carrying but the method may comprise a cradle 15, Fig. 4, for supporting a reclining body, rockable about an horizontal axis between limiting positions, and made of material transparent to X-rays. The cradle is supported on a fixed base 18 by springs such as 19, 20 which are biassed so as to urge the cradle towards one of its limiting positions. In order to rock the cradle to its other limiting position, a wire 21 secured at one end to a lug 27 on a framework 16 surrounding the cradle can be wound to a variable extent on a ratchetcontrolled shaft 22 mounted in the base 18 and operable by a hand wheel 25 or by motor. An aperture in the base accommodates a grid assembly 26 in which a flat grid 5, Fig. 3, is slidable in guides 71 which are slightly inclined to the direction of the grid strips, the movement being effected against biassing springs 8 by rotating an eccentric 9 through worm gearing from a shaft 13 which may be the same shaft as 22, Fig. 4, so that the hand wheel 25 or equivalent motor serves both to rock the cradle 15 between its limiting positions and also to displace the grid lines transversely to their length through a distance equal to the width of an opaque strip of the grid. The grid assembly includes a slideway for accommodating the sensitive plate or film. Several grid assemblies and their associated control gear may be similarly disposed at intervals along the base 18 for simultaneous operation ; or one grid assembly may be transferred in succession to various housings provided along the base to permit the different radiographs to be made in succession. A modified apparatus is described for making radiographs of a person standing on a turntable adjustable to and from vertical pillars supporting the grid and film or plate assembly, the grid having its lines vertical and traversable horizontally in a frame similar to that shown in Fig. 3, and the assembly being preferably adjustable up and down the pillars. If a parallax panoramagram is to be made, the grid has transparent lines narrower than its opaque lines, and the exposure is made either continuously or intermittently while the parts are moved in synchronism or co-ordination. If a parallax stereogram is to be made, the grid has transparent and opaque lines of equal width, and two exposures only are made, one in each of the limiting positions of the parts. The carrier of the body may be adapted to rock about an axis extending in any desired direction which does not pass through the ray-source.