Time Rectification System for In-Beam TOF-PET

A time rectification system for a InBeam TOF-PET was described. It consists of a pair of BaF₂(40 mm×45 mm) crystals coupled to Philips photomultipliers XP2020Q and a time coincidence electronic system using standard NIM modules. The best coincidence timing resolution of the system for pairs of 511 keV gamma rays is 576 ps. Some factors affecting the time resolution were primarily discussed, such as the types of photomultiplier tubes (PMT), the model of signal readout, the effects of different discriminators and timing amplifiers. The experiment results show that the signal read from the PMT dynode can get the optimum resolution; the PMT types, especially the rise time and electronic transmit time greatly affect the system performance. The shorter the rise time and electronic transmit time for the PMTs is, the better the timing performance is. The system timing performance is also related to the electronic combination.