Energy and Timing Response of Six Prototype Scintillators for TOF-PET

Abstract

The recent development of fast scintillating crystals with high light output (such as LaBr3, LYSO, and LSO) has made it possible to incorporate time-of-flight information into whole-body positron emission tomography scanners (TOF-PET). The development of fast scintillators has continued, and scintillators such as CeBr3 and the six crystals we report on here are candidates for future TOF-PET scanners. We have performed preliminary tests on six prototype scintillating crystals composed of YI3 (2% Ce), (Lu,Gd)I3 (2% Ce), Lul3 (10% Ce), Lul3 (5% Ce), Lul3 (2% Ce), and Ce(Br,Cl)3. The crystals were coupled to a PMT to observe 511 keV photons produced by positron captures in a 22Na point source. A LaBr3 coincidence detector was used in order to make timing resolution measurements. The prototype samples had a range of timing resolutions from 160 ps to 250 ps (FWHM). Ce(Br,Cl)3 was found to have the best timing resolution, with 160 ps, followed by Lul3 (2% Ce) with 180 ps. These results are competitive with the 160 ps we observed for a pair of LaBr3 crystals in coincidence with each other. The 2% Ce doped Lul3 sample was found to have the best overall energy response, with an energy resolution (FWHM) of 6% at 511 keV. Energy resolution and light yield measurements are presented for each of the crystals.