Method and apparatus for the examination of a body by penetrating radiation

The absorption distribution of γ- or X-radiation in a body is measured. The radiation penetrates from the source in a sector-shaped field through the body resting in a frame on a support and is then recorded by a detector system with individual scintillator detector. The sector field extends over an angle which allows a complete scanning by an orbital rotary movement of the detector system and source relative to the body. The sensitivity of the detectors deviates, however, from one investigation cycle to the other, so that the accuracy of the image reproduction is affected. In order to compensate for these sensitivity changes arising from drifts, an auxiliary radiation source, e.g. of americium, is used. It is placed at two different positions of the orbital movement in the beam path and acts upon the detectors with radiation whose intensity is greater by one order of magnitude. By means of a drift corrector computer and the measured intensity values of the auxiliary source, the sensitivities of the detectors are corrected, e.g. according to a linear law. (DG/LH)