Performance evaluation of the FastIC readout ASIC with emphasis on Cherenkov emission in TOF-PET

Abstract

Objective. The efficient usage of prompt photons like Cherenkov emission is of great interest for the design of the next generation, cost-effective, and ultrahigh-sensitivity TOF-PET scanners. With custom, high power consuming, readout electronics and fast digitization the prospect of sub-300 ps FWHM with PET-sized BGO crystals have been shown. However, these results are not scalable to a full system consisting of thousands of detector elements.
Approach. To pave the way toward a full TOF-PET scanner, we examine the performance of the FastIC ASIC with Cherenkov-emitting scintillators (BGO), together with one of the most recent SiPM detector developments based on metal trenching from FBK. The FastIC is a highly configurable ASIC with 8 input channels, a power consumption of 12 mW/ch and excellent linearity on the energy measurement. To put the timing performance of the FastIC into perspective, comparison measurements with high-power consuming readout electronics are performed. 
Main results. We achieve a best CTR FWHM of 330 ps for 2x2x3 mm3 and 490 ps for 2x2x20 mm3 BGO crystals with the FastIC. In addition, using 20 mm long LSO:CeCa crystals, CTR values of 129 ps FWHM have been measured with the FastIC, only slightly worse to the state-of-the-art of 95 ps obtained with discrete HF electronics.
Significance. For the first time, the timing capability of BGO with a scalable ASIC has been evaluated. The findings underscore the potential of the FastIC ASIC in the development of cost-effective TOF-PET scanners with excellent timing characteristics.