GB1526920A - Circuit for processing gamma-camera signals - Google Patents

Abstract

1526920 Gamma camera systems SELO SOC ELETTRONICA LOMBARDA SpA 1 Aug 1977 [10 Aug 1976] 32234/77 Heading H4F A circuit for computing coordinate signals x, y from the signals emitted by the photosensors 11 of a gamma camera includes dynamic attenuators 19 whose attenuation is changed in accordance with changes in the intensity of the detected gamma radiation. The photosensors 11 feed a matrix 17 and a summing circuit 13. The matrix provides signals proportional both to the coordinates and the intensity of the radiation. The signals are fed via delays 18 to the attenuators 19. The output Ze of the summing circuit 13 is proportional to the intensity and feeds a comparator 15 and a pulse amplitude analyser 14. If Ze falls within a range selected S by the operator a store 16 passes a signal corresponding to that range to the attenuators in order to adjust the degree of attenuation. The attenuator outputs pass direct and via a summing circuit 21 to units 20 which form the ratio of their inputs to provide the coordinate signals. The use of the attenuators obviates the need for the ratio units 20 to have a large dynamic range.