A New Solution of Time Synchronization in All-Digital PET based on TDC

High-accuracy time synchronization is one of the most important issues for basic detector modules (BDMs) in the all-digital PET. The existing synchronization solutions are hard to extend as strict requirement to the wires and interfaces. Once the number of BDM changed, the whole system's synchronization should be rebuilt from the beginning. In this paper, a new high-accuracy time-sync solution based on TDC with a feature of flexible extensible has been designed and implemented. It provides a protocol for time correction by any of two detectors through a simple communication: Each TDC implemented in every detector will record the accurate time of both the ASK and REPLY messages and sends the time-records to the other. By the exchange of time-records, the two detectors will calculate the time differences and correct it to for time synchronization. This method promise a lower requirement to the interfaces, and much simpler connecting and easier to be extended. And it can always offer a high accuracy time synchronization by just a soft correction, despite of the change or development of the PET system such as increasing or decreasing detectors.