Timing Optimization of Solid-State Photomultiplier Based PET Detectors

This article describes methods to improve the timing performance of solid-state photomultiplier (SSPM) based PET detectors in terms of readout electronics and device level optimization. Coincidence timing measurements based on coupling a 3 × 3 × 10 mm³ LYSO crystal to a Hamamatsu 50 ¿m 3 mm × 3 mm SSPM were performed. The effect of readout electronics´ bandwidth to coincidence timing resolution was measured by applying analog filters with different cutoff frequencies to the SSPM timing circuitry. High pass filtering with a 160 MHz cutoff frequency improved the timing resolution from 269±3.7 ps to 244±3.5 ps. Timing resolution was degraded substantially when cutting off the high frequency components of the SSPM signal, showing a strong dependency of the timing resolution on the high frequency components of the SSPM signal. An SSPM equivalent circuit was described to explain that embedding a quenching capacitor in the quenching network would enhance the high frequency component of the SSPM single photoelectron response, thus improving the timing performance.