Abstract: A control circuit for a scintillation camera is provided in which only discrete scintillation events are processed. When a scintillation event arrives, all light intensity signals below a predetermined threshold, indicating that the signals below the thresholds are not likely to be involved in the event, are blocked from the sum signal. The valid event discrimination circuit disclosed considers the sum signal of light intensity signals originating from only those photodetectors whose output signals are above the threshold. Valid event discrimination is not adversely affected by signals coming from photodetectors not involved in the event after the threshold detection takes place.