Investigation of LaBr3 detector timing resolution

Lanthanum bromide (LaBr₃) scintillation detectors are currently being developed for use in time-of-flight (TOF) PET. In recent years, studies have been aimed at the parameterization of the LaBr₃ scintillation properties. We have utilized the findings of these studies in the development of simulation tools to investigate and predict the performance of TOF PET detectors of realistic geometries. Here, we present a model to simulate the combined scintillator and photomultiplier tube (PMT) response to incident photons. This model allows us to study the effects of crystal response, geometry, and surface finish, PMT response, transit time spread, and noise, as well as discrimination techniques on the coincidence resolving time achievable in various detector configurations. Results from the simulations are benchmarked against several experimental measurements with two different PMTs and LaBr₃ crystals of varying cerium concentration and geometry. A comparison is also made to the time resolution achievable with LYSO. Good agreement between measurement and simulation has been achieved with detectors consisting of 4×4×30 mm³ crystals suitable for use in a TOF PET scanner. Ultimately, this guides the improvement of TOF detectors by identifying the individual contribution of each detector component on the time resolution that can be achieved.