Digital timing in positron emission tomography

Positron emission tomography (PET) requires accurate timing of events in order to properly discriminate between coincident and non-coincident events. The traditional solution to timing is based on custom ASIC designs, whose cost may not be justified in the design of an experimental small animal PET scanner. The new generation of PET scanners introduces the idea of continuous sampling of the detected scintillation pulse, in substitution of the event triggered acquisition systems. This approach enables new options to timing based on digital processing of the sampled pulse signal. This work proposes a time stamping algorithm based on the optically matched filter and compares the potential performance benefits of this approach versus other FIR filter designs, some of which have been already implemented by different authors. Results show that time resolution of the timestamp may be as 1 ns without the need of expensive high-speed converters when the proper processing is applied.