The Design And Implementation Of Multi-channel Scintillation Pulse Digitizing System Based On Multi-voltage Threshold Method

As a highly sophisticated imaging technology in nuclear medicine field, positron emission tomograhy(PET) has been widely used in aspect of various diseases diagnosis, therapeutic evaluation, as well as fields of function research in viscera and drug development.In recent years, with the development of scintillation detector and digitally sampling technology of scintillation pulses, more and more new PET system architecture has been introduced and attracted researcher's extensive attention. The appearance of new digital PET detectors that based on all-digital circuit architecture makes it possible for building digital PET systems. As well, a new type of LYSO/SiPM scintillation detector represented by the technique of PET detector laid foundation for achieving high performance TOF-PET system and the fusion of PET/MRI for multi-mode medical imaging study.A large quantity of data channels is a common problem in PET imaging systems.However, this problem is particularly apparent in new PET systems which based on SiPM detectors. In this work, we have combined this issue with a new digital scintillation pulse sampling method- multi-voltage threshold(MVT) sampling method, and designed and implemented a multi-channel digital pulse sampling system for cintillation detector's signal reading out based on SiPM. Firstly, by setting up a simulation database, we conducted a comprehensive research on the feasibility of MVT sampling method on digitizing SiPM pulses. Based on the simulation results, by upgrading the structure of classic MVT circuit, we propose a compact FPGA-Only MVT structure to improve the integration density.And the performance properties of the circuit has been evaluated. In addition, we have designed and implemented a 48-channels scintillation pulses digitizing system and comprehensively estimated the power consumption, dead time, as well as the sampling properties of scintillation pulses. Finally, around the system integration, updating and performance optimization of the multi-channel MVT scintillation pulses digitizing circuits, the thesis have made a in-depth and comprehensive research and discussion.