Evaluation of LFS continuous scintillation crystals for PET

The suitability of monolithic Lutetium Fine Silicate (LFS) continuous scintillation crystals coupled to 64-channel SiPM-TSV matrices for small animal PET has been evaluated. Three crystals of size 25.8 × 25 . 8 × 15 mm 3 were tested: LYSO white coating, LFS white coating (LFS-W) and LFS specular coating (LFS-S). Electronically collimated measurements were carried out to compare the performance of LYSO and LFS crystals. Mean energy resolutions of 14%, 17% and 19% were measured for LYSO, LFS-S and LFS-W respectively. Similar intrinsic spatial resolutions were found for all three crystals in the central region. Different versions of the light model used to estimate the interaction position of the photons in the detector have been studied. Further measurements with two detector heads of each crystal type in coincidence have also been carried out with a moveable 22Na source. A ML-MLEM image reconstruction code is used to reconstruct the data. Final position resolutions for all three configurations show similar values. Taking into account that LYSO and LFS present similar performance levels (and considering that LFS has better timing resolution than LYSO) we conclude that LFS is a valid substitute for LYSO.