Circuit arrangement for a detector for ionizing radiation

摘要

In an illustrated embodiment, a detector having a plurality of measuring fields is provided with a computer circuit for the formation of a difference signal which corresponds to the difference between the greatest and the smallest output signal of the measuring fields, a computer circuit for the formation of a sum signal which corresponds to the sum of the greatest and the smallest output signal of the measuring fields, and a division circuit is connected to provide an output as a function of the difference signal divided by the sum signal, as a measure of contrast over the selected measurement surface. The contrast signal can be utilized to control the duration of an exposure. Further, the contrast signal can be used for an automatic adjustment of the x-ray tube high voltage during an exposure so as to achieve an optimum picture contrast.