Abstract: Apparatus for measuring the density of vertebrae or the like, comprises gamma ray emission means for emitting gamma rays within a predetermined target area; detecting means for detecting the gamma rays passing through the target area; and rotatable positioning means between the emission means and the detecting means for supporting a subject and exposing the subject to the gamma rays in the target area at a plurality of different angles.

Abstract: A switch mechanism for an image intensifier hood in an x-ray diagnostics system is connected to a motor for moving the x-ray image intensifier toward and away from an examination subject. If the hood inadvertently comes into contact with the examination subject or a technician, the hood is displaced thereby actuating the switch mechanism and disengaging the motor to stop movement of the x-ray image intensifier, thereby avoiding injury to the examination subject and technician and avoiding damage to the x-ray image intensifier. The switch mechanism is constructed such that actuation thereof occurs upon the presence of forces acting on the hood in the direction of the luminescent screen surface or a direction perpendicular thereto, and each intermediate direction.