Characterization of a γ-ray detector based on square PSPMT array

Although gamma cameras have emerged in the sixties, their spatial resolution is still not sufficient to detect small tracer concentration abnormalities. Examinations like mammo-scintigraphy requires high spatial resolution and then the possibility to position the detector as close to the explored organ as possible. Diagnostic accuracy in nuclear medicine imaging can know a notable advancement with the emergence of the new position sensitive photomultiplier tube (PSPMT). This component allows to develop a compact gamma detector which fulfils these requirements. This study investigates the feasibility and the characteristics of a medium field of view high spatial resolution gamma ray detector based on an array of R8520 PSPMT coupled to a pixelated NaI(TI) crystal array. As first results, a photocathode uniformity variation of 1 to 3 was observed on the whole field of view. Energy resolution obtained is better than 10% FWHM at 140 keV in PSPMT centers. Concerning spatial linearity, it depends on the uniformity of the PSPMT used. Consequently, it will be necessary to develop linearity and energy correction methods.