Development of an event-by-event based radiation imaging detector using GGAG: A ceramic scintillator for X-ray CT

For a radiation imaging detector, low cost, high light output and short decay time scintillator is required. Although ceramic scintillators developed for X-ray computed tomography (CT) are possible materials for this purpose, the performance of the scintillation imaging detector using ceramic scintillators was not reported. For this purpose, we tested a ceramic scintillator originally developed for X-ray CT, Gd₃(GaAl)₅O₁₂:Ce (GGAG), combined with a position sensitive photomultiplier (PSPMT) to test whether an event-by-event based radiation imaging detector is possible to develop. The radiation imaging detector consists of a 0.1 mm thick GGAG plate, light guide and a 1-inch square PSPMT. The GGAG plate was optically coupled to the PSPMT with a 1 mm thick light guide between them. Anger principle was used for the position calculation of the radiations. We also conducted the comparison of the imaging detectors using 0.5 mm thick GGAG and single crystal Ce doped Gd₃(Ga, Al)₅O₁₂ (GAGG) plates. The spatial resolution and energy resolution of the developed imaging detector were 0.53mm FWHM and 11.5 % FWHM for 5.5 MeV alpha particles, respectively. The uniformity of the imaging detector at the central part of the field of view (FOV) was ±11%. We could obtain variable phantom images with the developed imaging detector for alpha particles. Reasonable performance was also obtained for beta particles, low energy gamma photons and X-ray. The spatial resolution of the imaging detector used GGAG plate was twice better and distortion was smaller than that of GAGG. We conclude that GGAG ceramic scintillator is promising for the development of radiation imaging detectors.