Collimator for x-ray diagnostic apparatus

Abstract

A collimator assembly for defining an aperture for the passage of a diagnostic x-ray beam in an x-ray diagnostic apparatus which may, for example, be used in computer assisted tomography. The collimator assembly comprises a framework adapted to be secured to the x-ray apparatus contiguous the x-ray tube, and includes a first and a second blade subassembly lying in a common plane with each other in the path of x-rays emanating from the x-ray tube. Leaf spring means connect each of the blade subassemblies to the framework, the leaf spring means biasing the first and second blade subassemblies into abutting relation to each other whereby to define a zero aperture condition for the passage of a diagnostic x-ray beam through said collimator assembly to the patient. Cam follower means are carried by each of the respective first and second blade subassemblies, and movable cam means are mounted on the framework and engageable with the cam follower means of said first and said second blade subassemblies whereby movement of the cam means is effective to move the first and second blade subassemblies against the biasing force of the spring means to a controlled degree of opening between the first and second blade subassemblies whereby to define a collimating aperture of a predetermined size between said subassemblies for the passage of a diagnostic x-ray beam of a predetermined size to the patient. A further feature of the collimator assembly is the use of a direct acting sensing arrangement for sensing the collimating opening between the two blade subassemblies. This sensing arrangement is embodied in an electromagnetic transducer in the form of a linear variable differential transformer.