Development of new high resolution detectors for small animal SPECT imaging

Summary form only received as follows: New high-resolution gamma-ray detectors are being developed for SPECT imaging of animals. Optimal collimators, reconstruction algorithms and image processing are an important part of the development of animal SPECT. These issues and recent advances in miniature gamma-ray detectors will be presented. Two lines of technical developments are being followed for high-performance gamma-ray imaging systems: the first uses state-of-the-art position-sensitive photomultiplier tubes (PS-PMTs); the second uses silicon-based photodiode detector arrays. Each are coupled to arrays of scintillation crystals. A small system has been assembled with newly developed PS-PMTs that has 1 mm CsI(Na) crystals and was fitted with a hexagonal parallel hole collimator (1.25 mm holes, 0.25 mm septa, 2 cm long). Line spread functions (LSF) were measured with 0.5 mm line sources filled with Tc-99m. The average FWHM of the LSF curves were 2.12±0.16 mm and 2.63±0.15 mm for 0 cm and 1 cm source-collimator distance, respectively. A LSF was made with 1.1 mm pitch (0.85 mm CsI(Tl), 0.25 mm spacing) CsI(Tl)-PIN detector collimated with matching geometry 1 cm long collimator. Mean FWHM=1.91±0.32 mm. Preliminary images from each system are presented