用于In-Beam TOF-PET的时间校正系统

Time Rectification System for In-Beam TOF-PET

设计和构建了用于In-Beam TOF-PET时间校正的定时系统。该系统是由1对BaF2(φ40mm×45mm)晶体耦合到光电倍增管XP2020Q和标准核电子学插件构成。经测试,系统对511keVγ射线测量的最佳符合时间分辨达576ps。对光电倍增管、信号读取方式、定时放大器以及甄别器等对该定时系统时间分辨的影响进行了测试分析。结果表明:从光电倍增管打拿级引出信号的读取模式的系统分辨率最佳;光电倍增管类型,尤其是它的上升时间和电子渡越时间对定时系统性能影响较大。光电倍增管的上升时间和电子渡越时间越短,其定时性能越好。系统的定时性能也与电子学插件的组合有关。

A time rectification system for a In-Beam TOF-PET was described.It consists of a pair of BaF2（φ40 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.