Evaluating the radiation detection of the RbGd2Br7: Ce scintillator by Monte Carlo methods

The purpose of this study was to investigate the radiation detection efficiency of the recently introduced RbGd2Br7:Ce (RGB) scintillator material by a custom developed Monte Carlo simulation code. Considering its fast principal decay constant (45 ns) and its high light yield (56000 photons/MeV), RbGd2Br7:Ce appears to be a quite promising scintillator for applications in nuclear medical imaging systems. In this work, gamma-ray interactions, within the scintillator mass were studied. In addition, the effect of K-characteristic fluorescence radiation emission, re-absorption or escape, as well as the effect of scattering events on the spatial distribution of absorbed energy was examined. Various scintillator crystal thicknesses (5-25 mm), used in positron emission imaging, were considered to be irradiated by 511 keV photons. Similar simulations were performed on the well known Lu2SiO5:Ce (LSO) scintillator for comparison purposes. Simulation results allowed the determination of the quantum detection efficiency as well as the fraction of the energy absorbed due to the K-characteristic radiation. Results were obtained as a function of scintillator crystal thickness. The Lu2SiO5:Ce scintillator material showed to exhibit better radiation absorption properties in comparison with RbGd2Br7:Ce. However, RGB showed to be less affected by the production of K-characteristic radiation. Taking into account its very short decay time and its high light yield, this material could be considered to be employed in positron imaging (PET) detectors. (c) 2006 Elsevier B.V. All rights reserved.