Multiplexing requirements for solid state photomultipliers in time-of-flight PET

The solid state photomultiplier (SSPM), an array of Geiger-mode APDs, developed by Hamamatsu Corp. has been evaluated for time-of-flight PET detectors. As it was demonstrated in previous work the SSPM is a promising photo sensor to achieve very good timing resolution for PET applications. Due to relatively small size of individual sensor (3×3 mm²) a large number of readout channels will be required in applications such as a whole body PET scanner. The obvious solution for this problem is multiplexing several devices into a single readout channel. To better understand the limits and trade offs involved for timing resolution a detailed analysis of the effects of dark current, amplifier noise, bandwidth and amplifier input impedance was done.