Patent GB-519166-A (GB)
Abstract: 519,166. R÷ntgen-ray apparatus. KIEFFER, J. Aug. 13, 1938, No. 23947. [Class 98 (i)] In an X-ray apparatus of the kind in which the ray-tube and the photographic plate or film holder are connected together so as to move simultaneously in opposite directions in planes parallel to the section of the body which it is desired to radiograph so that a ray through any point of the section always impinges at the same point on the plate or film, and wherein the focus . of the ray-tube is moved in an irregular path deviating from circular or rectilinear, the irregular movement is imparted to the ray-tube and thus to the plate or film holder by an arm which is connected at one end to the tube holder and carries at the other end a pin which engages, through a guide slot in a rotary disc, a groove of the desired irregular shape in a stationary plate. Means may be provided for stopping the motor driving the disc after it has imparted to the disc movement determining the cycle of movement of the tube holder. Provision is made also for imparting to the ray-tube from the rotatable disc a circular movement, or a rectilinear movement transverse to the X-ray table. The apparatus shown comprises a standard 15 adjustable along the table 10 on the horizontal rails of a frame 13, a clamp 18 serving to secure it in adjusted position. A sleeve vertically adjustable on the standard carries rails 20 which extend over .the table 10 and support a carriage 22 movable therealong across the table. The carriage 22 has rails 23 supporting a U-shaped holder 24 for movement in the longitudinal. direction of the table. The holder 24 has bearings for the trunnions of a cradle 26 carrying the ray-tube 27, and has an arm 37 adjustably and rigidly connected by a set-screw 38 to an arm 36 having a head 39 provided with an adjustable pin 40 engageable with one of several holes 33, 34 Fig. 6, in a disc 28 pivoted on the rail structure 20 and rotatable through worm gearing 31 by an electric motor 32 mounted on said structure When this disc rotates, the arm 36, moving parallel to itself, causes the tube holder 24 to copy the horizontal circular movement of the head 39.' The pin in this head may alternatively be engaged in a radial slot 35 in the disc 28 and be depressed therethrough so as to engage a spiral groove in a plate 41 fixed on the rail structure 20. In this case, when the disc 28 is rotated, the head 39 follows the spiral path in plate 41, and the tube holder 24 is caused by the arm 36 to copy this horizontal spiral movement. The arm 35 may alternatively be pivotally connected to the arm 37, in which case the tube holder 24 copies substantially only the component of the movement of the head 39 transverse to the table 10. An adjustable nose 47 on the disc 28 actuates the switch of the motor 32 to stop the disc when the desired movement of the tube holder has been completed. In order to co-ordinate the movement of the plate or film holder with that of the ray-tube, an arm 70 of adjustable length connected to an extension 72 of a trunnion of the ray-tube cradle 26 is universally pivoted at 68 to a sleeve slidable on a lever 57 which is universally pivoted at 58 to an arm 59 on a member supported on a rail 11 at the edge of the table 10, the lever having also at its lower end a slidable sleeve universally pivoted to an arm 56 connected to the plate or film holder 55 mounted below the table on a rail structure similar to that of the tube holder 24 so as to be capable of movement both along and across the table 10. The pivot 58 is adjustable along the lever 57, for selection of the body-section to be radiographed, by raising or lowering the member 63 according to a height scale 61; and the member 63 may be adjusted along the rail 11 into any desired position and secured by a screw 65. An apertured ray-shield 80 mounted below the ray-tube on a structure similar to that of the tube holder 24 has an arm 83A universally pivoted to a sleeve on the lever 57 so that the shield copies on a reduced scale the movements of the tube holder. A Bucky grid 90 may be supported either on the plate or film holder 55, or over said holder 55 so that it copies only the component of the movement thereof along the' table. To adjust the tube over the body, movement along the table 10 may be imparted to the entire structure comprising tube stand 15, tube holder 24, lever 57, and plate or film holder 55 after releasing the clamping screws 18, 65. Automatic movement may be imparted during the radiograph exposure either to this entire structure, or to the tube stand only if the clamping screw 65 is engaged, by a belt 95 which is detachably connected to the tube stand at 96 and passes over pulleys 97 and a larger pulley 98 to which it is connected at 99. Motion is imparted to the pulley 98, after releasing a catch 101 holding it, by eccentric weights 100, 103, which are adjustable on the pulley to determine the extent of the motion. The adjustibility of the arm 36 on the arm 37 permits stereographic radiographs to be taken with the tube holder 24 in two initial positions displaced relatively to each other across the table 10. Alternatively, stereographic radiographs may be taken by displacing the entire tube stand assembly to two different initial positions along the table after releasing the clamps 18, 65.