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 mm
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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.