Improvement of Compton imaging efficiency by using side-neighbor events

The Compton-imaging efficiency has been improved for 3D position sensitive room-temperature CdZn Te gamma-ray detectors by properly calibrating and classifying charge-sharing events. Interactions that are collected by multiple side-by-side neighboring pixels are found to have unique time-amplitude walk behavior that had previously resulted in improper depth reconstruction. After properly reconstructing the depth of interaction, these charge-sharing events can be treated as a single interaction and included in the Compton imaging reconstruction algorithms. Events shared by neighboring pixels are classified as charge-sharing based on their separation in depth and the energy collected by each pixel. By including these charge-sharing events in the imaging reconstruction, the imaging efficiency is improved by 33% and 140% for 662 keV and 1333 keV incident photons, respectively. A simulation further shows that over 80% of the side-neighbor three-pixel events at 662 keV are classified as charge sharing and 80% of these classified events reconstruct a correct image.