Scintillation arrays characterization for photon emission imaging

The use of position sensitive photomultiplier tubes (PSPMT) in Nuclear Medicine imaging has recently produced some major steps forward in this field. In fact a dedicated camera for the organ under examination can improve imaging performances. However, in order to maximize them, scintillating crystals arrays have to be employed. In this work 13 Csl(Tl), Csl(Na), Nal(Tl), YAP(Ce) arrays were tested. Square pixel active area ranged between 1×1 and 2×2 mm2 and thickness from 1 to 10 mm. Light output and energy resolution responses versus photon energy and pixel thickness were measured using a standard bialkali PMT. Scintillation light spatial distribution were analyzed coupling Csl(Tl) arrays to a recently available multianode 16 channel linear array PMT. Light output study shown that Csl(Tl) is the best considered material, optimizing optical, mechanical requirements and costs. Light output as well as energy resolution resulted independent on pixel area, but strongly dependent on thickness. Csl(Tl), 1 mm thick, gave the best energy resolution values (13-14% FWHM, at 122 keV). The light output aperture angle as well as spatial resolution values resulted roughly independent on crystal geometry. The light spread resulted slightly affected by crystal pixel size. Measurements allow to foresee imaging performances of many PSPMTs coupled to the investigated arrays and give a good set of data for simulations comparison.