Hardware setting optimization for a 1mm3 resolution clinical PET system

We are constructing a dual-panel PET system dedicated to locoregional imaging (e.g. breast, head/neck, etc). The modular data acquisition electronics uses the RENA-3 application specific integrated circuit (ASIC) to read out position-sensitive avalanche photodiodes (PSAPDs). The RENA-3's settings must be optimized to extract the best timing resolution and ADC dynamic range mapping performance. In the constructed dual-panel system prototype, which has a sensitive area of 160mm by 33mm by 64mm, two PSAPDs are replaced by a board that injects synchronized charge pulses into the readout system to simulate coincident PSAPD hits. A capacitor divider network then splits the charge pulse into a saturated timing trigger channel and an energy channel. We tested the effects of different timing to energy charge division ratios, as well as data acquisition trigger thresholds, on timing resolution and ADC dynamic range. Using a high charge division ratio of 5:100,000 achieved timing resolution improvements of 28% at 100 keV, 13% at 200 keV, and 9% at 300 keV, as well as a 30% improvement in ADC dynamic range usage in comparison to a 27:100 ratio. The measured timing jitter was 4.06 ns, 2.61 ns, and 2.33 ns FWHM for input pulse energies higher than 300 keV when using trigger acquisition thresholds of 40, 65, and 100 keV, respectively.