Development of a Small-Animal PET System

Developments in small-animal positron emission tomography (PET) technology aim at reaching spatial resolution in the submillimeter range and increasing the system sensitivity. Various detector schemes have been implemented in complete tomographic systems for in vivo animal imaging. These include small scintillation crystals read out by multichannel-photomultiplier tubes with optical fibers to guide the light, phoswich detectors, and direct coupling of semiconductor detectors to small scintillation crystals. One design uses avalanche photodiodes (APDs) for the detection of scintillation light. A prototype sector scanner was the first to combine fast lutetium oxyorthosilicate (LSO) crystals with APDs. Based on the results from this tomograph, a new system is being built with smaller detector elements for improved spatial resolution and sensitivity. In this overview paper, the concepts, technical realization, and expected performance of this system are described.