Performance evaluation of a pixellated Ge Compton camera

An ongoing project is being carried out to develop a high purity germanium (HPGe) Compton camera for medical applications. The Compton camera offers many potential advantages over the conventional gamma camera. The camera reported in this paper comprises two pixellated germanium detector planes housed 9.6 cm apart in the same vacuum housing. The camera has 177 pixels, 152 in the scatter detector and 25 in the absorption detector. The pixels are 4 × 4 mm2 with a thickness of 4 mm in the scatter detector and 10 mm in the absorption detector. Images have been taken for a variety of test objects including point sources, a ring source and a Perspex phantom. The measured angular resolution is 9.4° ± 0.4° for a 662 keV gamma-ray source at 3 cm. Due to the limited number of readout modules a multiple-view technique was used to image the source distributions from different angles and simulate the pixel arrangement in the full camera.