Initial studies of high resolution PET detectors using a novel dual-ended readout for organ-dedicated imaging

To image smaller organs such as the breast, heart and prostate using PET, there is a need for developing organ-dedicated PET systems that offers higher spatial resolution, high sensitivity, and low cost. This study will focus on developing the PET system with a dual-panel geometry. This study proposes a novel duel-ended readout method with an asymmetric SiPM design: the front end of the crystal array couples to a 4×4 SiPM array of 6×6 mm
²
size without optical light guide for optimal timing resolution, and the back end couples to an 8×8 SiPM array of 3×3 mm
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size for high spatial resolution. High DOI resolution can be achieved using the ratio of signal energy detected by the SiPM at one end to the total energy from both ends, with a crystal thickness of 20mm to ensure high detection efficiency. The dimension of the crystal arrays studied is 25×25×20 mm
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with the end area matches the area of the SiPM arrays. The TOFPET2 ASICs of PETsys Electronics were used to individually digitize and process the 64 signals coming from an SiPM array. All crystal can be clearly resolved in the flood image. The average energy resolution of the detectors was 14.0% and 16.3%. The event timing was determined using energy-weighted averaging method, resulting in CTRs of 242 ps and 282 ps for the two arrays with an energy window of 410-610 keV, respectively. The dual-ended readout detectors developed in this work provide good CTRs and a high three-dimensional position resolution, suitable for developing organ-dedicated PET scanners, capable of achieving simultaneously uniform and high spatial resolution, high sensitivity and high timing resolution.