A row-column summing readout architecture for SiPM based PET imaging systems

Recent developments in the area of Positron Emission Tomography (PET) detectors using Silicon Photomultipliers (SiPMs) have demonstrated the feasibility of higher resolution PET scanners due to a significant reduction in the detector form factor. However, reduced size implies a corresponding increase in the detector density, resulting in a proportional rise in the number of channels interfacing a SiPM array with the digital backend. This paper explores a row-column-diagonal decoding architecture to simplify and reduce the required channels between the individual elements in the SiPM array, and the backend digital electronics. Accumulation of noise presents itself as a challenge to the row-column summation architecture. This may lead to an increased chance of false triggering as compared to a more traditional approach with dedicated single-channel readout for each individual SiPM. This work explores various circuit implementation approaches for threshold detection as applied to front-end electronics, which minimizes the accumulation of dark noise, and reduces the possibility of a false triggering event. Current comparator topologies are explored in the context of fastest turn-on time and the impact of realizing these threshold detection techniques in the context of our row-column summation architecture. The proposed readout electronics is currently being realized in STMicroelectronics 130 nm CMOS process.