Abstract: A primary radiation diaphragm for use in a medical radiation application apparatus for gating the x-ray beam emitted by a radiation source onto a desired region has first and second diaphragm plates and an actuator for the diaphragm plates having two ranges of adjustment. The first diaphragm plate is adjusted within the first range of adjustment by movement of the actuator, and the second diaphragm rate is adjusted by moving the actuator within the second range of adjustment.

Abstract: The diaphragm plates are individually adjustable in two-dimensional fashion. Semi-transparent diaphragm sections at the edges of the diaphragm plates limiting the radiation are adjustable perpendicular to the respective edge with a lever linkage such that the semi-transparent region becomes larger when the diaphragm is closed. A feedback control unit is present for operation. This feedback control unit has two operating pieces as an operating mechanism, which are displaceable by a user to positions similar to the diaphragm plates, and are electrically coupled to the feedback control unit to cause movement of the diaphragm plates to a position corresponding to the position of the operating plates.