Detector, shielding and geometric design factors for a high-resolution PET system

The authors evaluated the resolution, efficiency, and scatter rejection of a novel high-resolution PET (positron emission tomography) system designed for animal studies which is based on a 2-D modular detector system. A digital positioning system was evaluated by testing different encoding methods. Tungsten interplane septa of different thicknesses and geometries were evaluated by Monte Carlo simulations and experiments. The detector system consists of a 6×8 array of BGO crystals coupled to two dual photomultiplier tubes (PMTs). The crystals are 3.5 mm wide with 4-mm transaxial spacing and are 6.25 mm long with 6.75-mm axial spacing. PMT outputs are digitized, and Anger-camera-type logic is used to determine the X and Y location of the scintillator event. Data are then sorted into the appropriate detector using a column lookup table and the column dependent row lookup tables