MONTE-CARLO SIMULATION OF BAF2 DETECTORS USED IN TIME-OF-FLIGHT POSITRON EMISSION TOMOGRAPHY

To better understand the performance of the SP3000 time-of-flight PET machine we performed Monte Carlo calculations of photon interactions in a BaF2 detector module and calculations of crystal optics for BaF2 UV scintillation light. Evaluated were photon detection sensitivities, the amount of photon spillover, crystal crosstalk, inter-ring miscodes, and true-to-random coincidence ratios as a function of the lower level energy discriminator setting and crystal/photomultiplier tube energy resolution. UV light collection efficiencies for the timing tube and decode tube also were calculated assuming different crystal geometries, reflective materials and reflectances. For a typical SP3000 detector module the detection efficiency for single 511 keV photons varied between 20–60% depending on the angle of incidence. Crosstalk in the same ring was ∼3% and crosstalk between adjacent rings was ∼1%. The optical calculations indicated that the fast light component of BaF2 produced less than 35 photoelectrons at the timing tube photocathode for a 511 keV photopeak event and less than half this number of photoelectrons at the decode tube. Copyright © 1990 by The Institute of Electrical and Electronics Engineers, Inc.