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Small gamma imaging probe with millimeter spatial resolution

A small gamma imaging detector is being developed on the basis of either the Hamamatsu R5900-M16 and R5900-M64 multianode PMTs. This device is being developed for use in instances where a small field-of-view (FOV), high position resolution imager can be useful. Specific examples are in-vivo small animal studies and surgical intra-operative probes. Candidate crystal scintillators (NaI(Tl), CsI(Na), and YAP(Ce)), both in plate form and as square pixel arrays were tested for suitability for gamma ray imaging in the 22-122 keV range. CsI(Na) scintillator is shown to be the best choice for practical operation. With a simple and economical design the detector achieved good spatial resolution of 2 mm FWHM in the above energy range. The authors' first planned use will be in imaging an /sup 125/I (27-35 keV) tracer used in small animal (mouse) studies.