Influence of sensor arrangements and scintillator crystal properties on the 3D precision of monolithic scintillation detectors in PET

This paper reports the characterization and comparison of different sensor configurations for monolithic scintillation crystals via the calculation of a figure of a merit based on statistical (Fischer) information. The optimal precision of maximum likelihood determinations of interaction positions, i.e. where annihilation photons are absorbed in a monolithic (LSO) crystal, is approximated throughout a crystal block via Fischer information (related to the width of the maximum likelihood distribution) evaluated at a grid of points. Realistic positions and thus realistic distributions of points of interaction are estimated by applying a maximum likelihood algorithm to Monte Carlo data. The algorithm was based on pattern recognition using a Monte Carlo generated lookup table and the least square method. The precision of this method is compared with the optimal (Cramer-Rao) limit for selected points