PMT- cross-display scintillator block detector design and Monte Carlo study

Block detector using crystals coupled to circular photomultipliers (PMTs) is commonly used in positron emission tomography (PET). We design a novel PET block detector with cross-shape PMT layout (CSPL). The block detector consists of 9×9 lutetium orthosilicate (LSO) pixelated crystal array (2.2mm×2.2mm×10mm) and five PMTs (four 3/4 inch with circular envelope, one 3/8 inch with square envelope) arranging in a cross-shape layout with the small one in the middle. The crystals are separated by Teflon reflectors and optical grease to control the light distribution. Monte Carlo simulation package GATE is used to simulate the processes of both gamma ray interaction and light spread in LSO crystals. Impact of major resolution limiting parameters, including inter-crystal scattering, parallax effect and light spread in the crystals on the performance of the proposed detector design is investigated. Simulation results show that the proposed block detector design could get higher light collection and better position profile.