Evaluation of cerium doped lutetium oxyorthosilicate (LSO) scintillation crystals for PET

Abstract

A new scintillation crystal, cerium-doped lutetium oxyorthosilicate (LSO), was recently discovered, with light intensity 75% of NaI(Tl), scintillation decay time of 12 ns (30%) and 42 ns (70%), effective Z of 66, and density of 7.4 g/cc. The fast decay time and scintillation light output of LSO are superior to those of bismuth germanate (BGO) for positron emission tomography (PET) and the stopping power of LSO for 511 keV photons is only slightly lower than that of BGO. The authors directly compared the detection characteristics relevant to PET applications of small crystals of LSO (2*2*10 mm) with those of BGO. The energy resolution at 511 keV was 12% FWHM for LSO and two to three times wider for BGO. The coincidence timing of two opposing crystals, using a position sensitive photomultiplier tube (PMT) (Hamamatsu R2486), were 1.4 ns FWHM for LSO and more than three times higher for BGO. Using a fast PMT (Hamamatsu R3177), coincidence timing for LSO yielded 0.46 ns FWHM. These crystals are being used to simulate a small-scale PET scanner and to investigate its imaging performance. >