ALGORITHMS TO IDENTIFY DETECTOR COMPTON SCATTER IN PET MODULES

Using Monte Carlo simulation, we investigate algorithms to identify an d correct for detector Compton scatter in hypothetical PET modules wit h 3x3x30 mm EGO crystals coupled to individual photosensors. Rather th an assume a particular design, we study three classes of detectors: (1 ) with energy resolution limited by counting statistics, (2) with ener gy resolution limited by electronic noise, and (3) with depth of inter action (DOI) measurement capability. For the first two classes, select ing the channel with the highest signal as the crystal of interaction yields a 22-25% misidentification fraction (MIF) for all reasonable no ise fwhm to signal (N/S) ratios (i.e. <0.5 at 511 keV). Algorithms tha t attempt to correctly position events that undergo forward Compton sc atter using only energy information can reduce the MIF to 12%, and can be easily realized with counting statistics limited detectors but can only be achieved with very low noise values for noise limited detecto rs. When using position of interaction to identify forward scatter, a MTF of 12% can be obtained if the detector has good energy and positio n resolution.