Crystal identification in modular array detectors for high spatial resolution PET

The use of detector arrays in PET has been proposed and studied as a economical means of obtaining very high resolution images. The properties of detector arrays for use in high resolution PET scanners were investigated. Analytical approximations and Monte Carlo simulations were used to design detector arrays consisting of six to eight crystals coupled to two photomultipliers to allow identification of the individual crystals. Arrays of 2.85 mm thick crystals of Bismuth Germanate (BGO), Gadolinium Orthosilicate (GSO), and Barium Fluoride (BaF/sub 2/) were examined. The effect of interdetector materials such as lead, and plastic on positioning accuracy was tested. Assembled arrays of six 2.85 mm thick BGO crystals yielded line spread function FWHMs of 2.4 to 3.2 millimeters. The limiting resolution of detector arrays was found to be defined by the scintillation light yield of the crystals, the light gathering efficiency of the detector arrays, and the fraction of interdetector scatter