Multiple occupancy considerations for the SmartPET imaging system

The SmartPET collaboration is investigating the use of two planar high-purity germanium double-sided strip detectors as a Compton imaging positron emission tomography system. Monte Carlo simulations suggest that a large proportion of interactions within the detectors will occur within a small spatial volume, introducing significant ambiguities within the position and energy measurements made by the detectors. Under certain circumstances, the ambiguities will result in multiple interactions being detected as a single interaction. This investigation studied the effect of such multiple occupancies and found that approximately 45% of 511 keV events include multiple interactions within a 5×5×20 mm3 volume. Nevertheless, the effect on the quality of the final data remains quite acceptable.