Patent GB-670239-A (GB)
Title: Improvements in roentgen apparatus
IPC: A61B6/10
Filed: 1948-05-11
Abstract: 670,239. X-ray apparatus. SCHONANDER AKTIEBOLAG, G. May 11, 1948 [May 12, 1947], No. 12942/48. [A Specification was laid open to inspection under Sect. 91 of the Acts, Nov. 13, 1948.] Class 98 (i). A patient-platform mechanism for radiography, particularly for pulmonary photofluorography, comprises a platform for adjusting the position of the patient, the platform, when loaded by, for instance, a patient, being movable downwards against the force of a yielding upwardly-acting counter-load, such as a counterweight or spring, the platform being controlled by a preferably regulatable speedlimiting member, and being provided with means for arresting the platform at the desired level. As shown, the apparatus is of the kind having a base-plate 1 carrying an X-ray tube 2 on a stand 3 and the lower piece 11 of the stationary front part of a patient box, the upper piece 12 of which carries a fluorescent screen 4, and the framework 5 carrying the photographic camera unit 6. The platform 1 is detachably supported by lugs 24 on columns 22 slidable on guides 28 and connected at their upper ends by a bar 23. Cables 29 attached to the columns pass over pulleys 30 and are connected to a counterweight 31, which normally tends to raise the platform and its supporting frame, but is raised when a patient stands on the platform. A rod 32 fixed to bar 23 carries a piston moving in a cylinder 33 containing a liquid or a gas which is forced out through an outlet valve operated by a lever 34 when the platform moves down. Preferably, lever 34 is actuated by a sleeved cable 36 and a handle 35. The liquid passes through the outlet valve to a container preferably above the cylinder, and preferably returns by an inlet valve of greater capacity. Another form of platform mechanism is described in which the platform has guides slidable on vertical members, and a cable attached to the platform passes over a driving pulley, and then over idler pulleys to support a counterweight. The driving pulley is geared to a drum against which a brake block is pressed by a spring-urged lever, and a shaft carrying brake blocks urged by centrifugal force against the inside of a fixed drum. When the patient is on the platform the lever is raised to allow the platform to descend at a speed limited by the action of the rotatable brake blocks on the drum. The driving pulley may be automatically disengaged when the patient steps off the platform, which is then raised by the counterweight. The speed limiting device may be regulated by adjusting a spring between the brake blocks, or may consist of paddles rotating in a closed liquidfilled chamber. The platform may be raised as by a hydraulic lifting device. The Specification as open to inspection under Sect. 91, includes the subject-matter of Specifications 670,240 and 670,289, and also states that the platform may include a balance for weighing the patient, the reading thereof controlling by transmission means a pointer of a scale which may indicate directly the exposure time required, this time being taken as proportional to the weight of the patient. Alternatively, the transmission means may effect voltage control of the X-ray tube. The balance is preferably operated when the platform has reached its final position. An optical system for correcting spherical aberration, comprising curved reflecting surfaces with their axes at right angles, is described. This subjectmatter does not appear in the Specification as accepted.