Improvement of Compton imaging efficiency by using side-neighbor events

In a pixelated detector, an electron cloud can be collected by and shared between several adjacent pixels. By including these charge-sharing events, the Compton-imaging efficiency can be improved for 3D position sensitive room-temperature CdZnTe gamma-ray detectors. Simulated photopeak events that trigger three separate pixels with two pixels being adjacent to each other, which are called three-pixel side-neighbor photopeak events, were divided into six categories based on interaction type. Analysis of this simulation shows that the most effective strategy is to treat all side-neighbor events as charge-sharing events and to combine all side-neighbor signals into a single interaction. By including these side-neighbor events in the Compton image reconstruction, we can improve the imaging efficiency by 45% and 160% for 662 keV and 1333 keV incident photons, respectively. The simulation also shows that 76% of these combined events reconstruct to rings that pass the source direction. Measured data is presented to validate the simulation results.