Tomographic apparatus for producing transverse layer images of a radiography subject

A tomographic apparatus for producing transverse layer images of a radiography subject, having a radiation measuring arrangement which comprises a radiation source producing a radiation beam which penetrates the radiography subject and whose cross sectional extent perpendicular to the layer plane is equal to the layer thickness, and also a radiation receiver which determines the radiation intensity behind the subject, a movable support carrying the measuring arrangement and displaceable parallel to the plane of the layer, a rotating track carrying the movable support, and motor means for driving the rotating track for irradiating the radiography subject from various directions and for driving the movable support, and a measured value converter for transforming the signals supplied by the radiation receiver into a layer image, characterized in that a ring (10) is rotatably mounted on a common axis with the rotating track (2) and is driven by the motor means (4) for a continuous rotation of said ring (10), and a step by step drive unit (6, 7, 8) energized by the motor means (4) and driving said rotating track, a gear wheel (14) being rotatably mounted on the rotating track (2) and being driven by said ring (10), and crank means (15) driven by said gear wheel (14) for effecting movement of said movable support.