Siemens Aktiengesellschaft

Burghard Weinkauf

Gunter Luderer

Reiner Liebetruth

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.

Semiconductor X-ray detector

In the illustrated embodiment, a series of detectors subject to additive errors in measurement due to high voltage variations is provided with a reference channel having a detector or an equivalent component which is not exposed to the radiation, but which is responsive to high voltage fluctuations. The output from the reference channel during each measurement cycle is supplied to multiplier circuitry which receives from each channel as a second input a stored constant representing the deviation in sensitivity of the channel detector as compared to the reference detector or equivalent. The output from the multiplier is combined with the measured value from such channel by means of a subtractor circuit so as to correct the output from the channel for the errors introduced by fluctuations in the high voltage supply.

Tomographic x-ray apparatus for producing transverse layer images

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.

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Erlangen, Germany

Burghard Weinkauf