Comparison of Timing Measurement Methods of Dual-Ended Readout Scintillator Array PET Detectors

The main focus of this work is to compare different timing measurement methods of individual silicon photomultiplier (SiPM) arrays and dual-ended readout PET detectors. Two lutetium yttrium oxyorthosilicate (LYSO) crystal arrays with 3.10×3.10×20 mm3 crystals, enhanced specular reflector (ESR), and barium sulfate (BaSO4) reflector and one LYSO crystal array with 1.88×1.88×20 mm3 crystals and BaSO4 reflector with dual-ended read out by 8×8 SiPM arrays of 3×3 mm2 active pixel area were measured. Signals of the SiPM arrays were processed individually using 64 channel PETsys TOFPET2 ASICs designed for time-of-flight PET applications. For the SiPM arrays, an energy square-weighted average timing method using the timings of the fastest 2 SiPM pixels was found to provide the best coincidence timing resolutions (CTRs). For the dual-ended readout detectors, the method of using the energy-weighted average timings of the two SiPM arrays provided the best CTR of 234 ps for the detector using 3.10×3.10×20 mm3 crystals and ESR reflector, 239 ps for the detector using 3.10×3.10×20 mm3 crystals and BaSO4 reflector, and 275 ps for the detector using 1.88×1.88×20 mm3 crystals and BaSO4 reflector for an energy window of 410-610 keV. The dual-ended readout detectors developed in this work provide better CTRs than those of single-ended readout detectors and a high three-dimensional position resolution which can be used in the future to develop whole-body PET scanners to simultaneously achieve uniform high spatial resolution, high sensitivity and high timing resolution.