Front-End Electronics Design for 3-D Position Sensitive TOF-PET Detector That Achieves ~120-ps CTR and ~1.2-mm DOI Resolution

This study introduces and evaluates a new front-end electronics design for time-of-flight (TOF) 3-D position sensitive (TOF-3-DPS) detectors with a side-readout configuration. This design employs an RF amplifier and summing circuit-based timing multiplexing scheme to achieve 24:1 timing multiplexing. Additionally, complex programmable logic devices are utilized for precise energy measurement and 3-D positioning, accommodating both single and multiinteraction intercrystal scatter (ICS) events within a detector unit. Experimental results on a single $3\times 3\times $ 10 mm3 LYSO:Ce crystal side-coupled to three $3\times $ 3 mm2 SiPMs in a $4\times 6$ SiPM array demonstrated a $9.17\pm 0.20$ % energy resolution, a $1.20\pm 0$ .26 mm FWHM depth-of-interaction (DOI) resolution, and a $112.46\pm 1.91$ ps FWHM coincidence time resolution (CTR) after DOI-related time skew correction. Further tests on a detector unit comprising a $4\times 2$ array of $3\times 3\times $ 10 mm3 LYSO:Ce crystals, side-coupled with the same $4\times 6$ SiPM array, yielded a $10.56\pm 1.05$ % energy resolution and a $121.28\pm 3.35$ ps FWHM DOI-calibrated CTR. The ICS event ratio for each crystal element within the detector unit was also preliminarily assessed. The front-end readout circuit consumes approximately 0.75 W per 24-SiPMs detector unit and features a compact $27\times $ 95 mm2 footprint capable of reading out two units, enabling easy stacking of multiple units to form a complete TOF-3-DPS detector module.