Timing resolution of improved LGSO crystals for TOF PET imaging

Recently, Hitachi Chemical Corp. has demonstrated the capability of controlling decay time and light output of LGSO crystals. Changing the cerium concentration can reduce the decay time of the crystal while preserving the light output. It has also been shown that LGSO crystals can be produced with improved light output on longer wavelength that fit to APD type application. In this paper, the decay time, timing resolution, and energy resolutions of these improved LGSO crystal were measured, Using a fast timing PMT, H6533, LGSO crystals of 4×4×25mm³ with a shortest decay time of 33ns had a 25ps improved timing resolution of 250ps compared to standard LGSO crystals. Shorter crystals of 4×4×10mm³ also showed a 15ps improved timing resolution of 206ps compared to the standard crystals. They are also compared to standard LYSO crystal from Crystal Photonics Inc.