Recent developments in pixelated gamma ray detector and imaging system

Recently gamma ray detection technologies become very important in the fields of medical application, space, and environment. Pixelated detectors and electronics are necessary to achieve high-resolution gamma ray detectors. Especially high resolution PET (positron emission tomography) system has been a driving force for developing pixel gamma-ray detectors. A pixel gamma detector is composed of granulated crystals and photo-detectors with highly integrated circuits (ASIC) to process the large number of channels. Recent development of these technologies is reviewed here. (author)