Abstract: A detector system for computer tomography or computer radiography contains a plurality of flat detectors which are arranged side by side in the plane of a fan-shaped beam of ionizing rays. According to the invention, detectors of high purity germanium are provided, whose volume is selected so that the contribution of the generation-recombination current to the shot noise of the detectors is substantially smaller than customary in detectors for ionizing rays. With these detectors one obtains a good local resolution as well as a good signal-to-noise ratio and one requires no vacuum and no cooling.