Abstract: In the illustrated embodiments a row of semiconductor diodes is provided with intervening fluorescent layers and with fluorescent layers at the opposite ends. The x-radiation may impinge on one end of the detector such that the additional layers provide increased sensitivity. In a second embodiment, the radiation impinges laterally of the detector so that each fluorescent layer receives an individual sample of the impinging radiation, and the output from respective diodes may be individually stored as a measure of the respective samples. In an illustrated x-ray tomographic apparatus, the edge faces of the fluorescent layers are equidistant from the focus of the x-ray tube so as to sample successive portions of a fan-shaped x-ray beam.

Abstract: In an illustrated embodiment radiation detectors are associated with respective signal processing channels which have components subject to errors which vary in the course of time because of external influences such as temperature and aging effects. Each signal channel is subjected to a calibration cycle by introducing an impulse change in the supply voltage common to the respective detectors. Where xenon detectors are utilized in conjunction with integrators, the variation in detector gas volume and capacitance due to manufacturing tolerances may be compensated by storage of a constant value. Thereafter, calibration cycles may provide for automatic correction of the measurement signals for subsequent errors. A calibrating cycle can take place prior to initiation of a patient radiograph, or between two x-ray flashes during the angular scanning process.