PET data acquisition (DAQ) system having scalability for the number of detector

In a conventional PET data acquisition (DAQ) system, all detector signals are transferred to and processed by a single coincidence module so that high data processing speed is generally required for it. In other words, scale of a PET system (number of detector modules) was greatly limited by the performance of the coincidence module. In this situation, we developed a new DAQ system having scalability for the number of detector modules. Therefore, the new DAQ system can be applied widely for a small-scale system to a large-scale clinical system. The DAQ system was designed aiming for connecting 256 PET detector modules in maximum and for connecting multiple coincidence modules to form a daisy-chain structure transferring the detector signals to each other. The DAQ system consists of the three modules: one for generating data of position, energy and timing by processing detection pulse signals digitally, one for judging coincidence and generating coincidence event data and one for connecting the coincidence modules and a console Pc. This structure separates paths of single event data and coincidence event data and realizes that the transmission load between coincidence modules can be reduced. We confirmed using Matlab/Simulink that the count loss of coincidence events in the proposed DAQ system was only 5.5 % at the total coincidence count rate of 30 Mcps/system. We also measured the timing jitter of the DAQ system and the result was 97 ps. These results indicate that the DAQ system significantly reduces coincidence count losses and provides the timing performance enough for TOF-PET scanners.