Depth of interaction calibration and capabilities in 2?2 discrete crystal arrays and digital silicon photomultipliers

In this study we quantify the depth of interaction (DOI) capabilities of unique dual light sharing arrays (DLSA) on digital silicon photomultipliers. Side and entrance surface DOI calibration methods were tested. Results showed timing resolutions of 350-370 ps and energy resolutions of 10-12% while achieving a DOI position estimation of 6-7 mm FWHM. Significant improvements in depth estimation error were found when using maximum likelihood estimation and 3-4 depth bins. It was found that entrance surface DOI calibrations provide similar results such that eventual PET systems may be easily calibrated using a monoenergetic flood source.