Systems and methods for improved collimation sensitivity

A detector assembly is provided that includes a semiconductor detector, a pinhole collimator, and a processing unit. The semiconductor detector has a first surface and a second surface opposed to each other. The first surface includes pixelated anodes. The pinhole collimator includes an array of pinhole openings corresponding to the pixelated anodes. Each pinhole opening corresponds to a corresponding group of pixelated anodes. The processing unit is operably coupled to the semiconductor detector and configured to identify detected events from the pixelated anodes. The processing unit is configured to generate a trigger signal responsive to a given detected event in a given pixelated anode, provide the trigger signal to a readout, and, using the readout, read and sum signals arriving from the given pixelated anode and anodes surrounding the given pixelated anode.