Performance of a PET detector with a 256ch flat panel PS-PMT

A 256ch flat panel position sensitive photomultiplier tube (FP-PMT) is a promising device for a PET detector because of its large opening area, 52mm × 52 mm, and small dead space. The useful area of the FP-PMT is 89% to the opening area so that the FP-PMT affords optical coupling with a 16 × 16 array or scintillation crystals having 3 mm × 3 mm bottom area. Its 14.7 mm thickness will also ensure a compact volume and less weight for the PET apparatus. We evaluated performance by irradiating 511keV gamma ray onto GSO crystals coupled to a prototype of the FP-PMT. The resultant positioning image map assure its capability for crystal identification. In a series of measurements, we used a multilayer polymer mirrors for a reflector of the detector. It was cut or marked for folding in precise sizes using a CO₂ gas laser. Making folds on the reflector by a laser contributed to easier assembly of the detector composed of many small crystal elements and may potentially be utilized in various shaped detectors.