Radio-diagnostic equipment with shutter

DETAILED DESCRIPTION In accordance with the principles of the invention the device which regulates the position of the individual lamellae of the shutter has spring elements which by physical means can be deflected from an initial position.
In this way, it is possible through a simple mechanical construction to individually move the lamellae of the shutter simultaneously toward each other until each lamella touches the outer contours of the object under examination.
A simple process for adjusting the lamellae is described in a preferred embodiment wherein the spring elements consist of flexible strips which are, for example, of bimetal sheets or shape memory alloys.
Such shape memory alloys are well known and described, for example, in the journal "Metall", 39, 1, 1985, pages 34 to 38.
Spring elements produced from these alloys can be permanently deformed at low temperatures.
By heating these elements above a certain temperature, they again assume their original shape.
An individual simultaneous control of each lamella can take place when each lamella has a flexible strip assigned to it.
An advantageous design of an evaluation circuit is described including a circuit to determine the position of the lamellae within the video image into which the clock pulses of a television camera and control signals which characterize each selected lamellae are fed.
The video signal is carried to an adaptation stage.
The adaptation stage and the position circuit are connected to a gate circuit to which a peak value detector is connected.
The output signal of the detector is applied to two comparison stages which compare it to adjustable threshold values.
A first counter is connected to the comparison stages which is connected to a further comparison stage which compares the output signal of the first counter with that of a second counter The further comparison stage controls the spring elements It has proven to be of advantage that the lamellae are arranged in parallel next to each other at both sides of the slit of the X-ray aperture The aperture can be adjusted to any desired shape if the lamellae are directed radially toward the aperture Rotation of the shutter can be omitted if the shutter consists of two shutter systems perpendicular to each other each system having a plurality of individual lamellae