Patent GB-652852-A (GB)
Title: Means for directly obtaining stereoscopic radiographic images of the parallax panoramagram type
IPC: A61B6/02
Filed: 1945-11-06
Abstract: 652,852. X-ray apparatus. RELIEPHOGRAPHIE, SOC. POUR L'EXPLOITATION DES PROCEDES DE PHOTOGRAPHIE EN RELIEF M. BONNET. Nov. 6, 1945, No. 29580. Convention date, July 29, 1944. [Class 98 (i)] Radiographs of the parallax panoramagram image type are produced by disposing, on opposite sides of a stationary object to be radiographed, an X-ray tube and a carrier containing both an image-recording radiographic surface and an X-ray line screen having intervals transparent to X-rays which are narrower than its opaque lines, the tube, object, and the centre of the line screen being in a straight line ; and rotating the tube and carrier about the object so that the X-rays from the tube after passing through the object reach the line screen at an inclination which varies throughout the recording. Alternatively, the tube may remain stationary and the object and carrier may be rotated about axes intersecting the X-ray beam and parallel to the lines of the X-ray line screen. Instead of varying the angle at which the beam meets the line screen to record the elements of the parallax panoramagram image, the line screen and radiographic surface may be maintained always perpendicular to the beam and a relative sliding movement between them performed during recording. A parallax panoramagram radiographic picture assembly may be produced by replacing the recording line screen by a transparent lenticular screen with cylindrical elements each of a width equal to the pitch of the line screen and an aperture angle (working diameter/focal length) equal to the angle swept out by the rays passing through the recording line screen. As shown in Fig. 1, the object 4 is supported on a vertically adjustable table 3, and the X-ray tube 1 and the carrier 2 for the X-ray line screen 15 covering a thick glass or cellulose acetate plate bearing a photographic emulsion on its rear surface, counter-weighted as at 11, 13 are mounted at opposite ends of a parallelogram linkage 5, 12, 5, 10 supported as a whole by the rods 5, which may be adjustable in length, pivoted at 6, 7 on a fixed standard which may be adjustable as to its height. The carrier 2 is rigidly attached along its rear surface to an extension of the rod 12, and the tube 1 is supported by a parallelogram linkage formed by the tube itself and rods 10, 5, 14. During taking, the tube 1 and carrier 2 are moved continuously between the full and chain-dotted line positions, thus exposing the strip of sensitive plate immediately behind the slit and the adjacent opaque portions. Instead of causing the plate carrier to rotate relatively to the X-ray beam, the X-ray line screen and the sensitive plate may be slid relatively to one another, whilst remaining perpendicular to the X-ray beam, as the tube moves round the arc of a circle centred on the object. In a modified apparatus, Fig. 8 (not shown), the tube remains stationary, and the object table and the carrier for the X- ray line screen and the sensitized plate, pivoted one above the other on a fixed standard with the pivots in line with the axis of the X-ray beam, are rotated in synchronism about the axis by a parallel motion system driven by an electric motor through a worm on the motor engaging a toothed segment carried by the arm of the parallel motion system, said rotation also operating a switch exciting and cutting off the X-ray tube. For viewing, the radiograph thus obtained is covered with a lenticular screen 20 of thickness equal to its radius of curvature which is equal to half the thickness of the plate 17, and having lenticles such that their aperture angle is equal to the angle through which the tube and carrier for plate and line screen are moved during taking. To allow the use for taking of a sensitive plate already having its lenticular screen for viewing in place, the apparatus of Fig. 7 is employed. The tube pivoted on the rods 10, 14 slides along the guide 29, and the carrier 2 for the lenticulated plate and covering X-ray line screen pivoted on a lower rod 12 slides on a guide rail 30, the carrier being pivoted at 32 and caused to rotate, so as to reduce the angle subtended by the image on the plate at the opening of the line screen by a roller 34 which is carried on arm 33 fixed to the carrier and which runs on a suitably chosen incline 35. The Specification as open to inspection under Sect. 91 also describes a modification of the embodiment described with reference to Fig. 8 (not shown), in which the X-ray line screen and plate are maintained perpendicular to the axis of the X-ray beam from the stationary tube whilst sliding relatively to one another to record the successive aspects of the rotating object. This subject-matter does not appear in the Specification as accepted.