Light output spatial distributions of CsI(Tl) scintillation arrays for gamma-rays imaging

Over the last years Nuclear Medicine and Oncology require the development of new scintigraphic imagers dedicated to particular organs and lesions, with improved performances with respect to presently available devices. In order to enhance the imaging responses, pixellated crystals have to be employed as scintillating devices coupled to position sensitive photomultiplier tubes. Some of major steps forward in this field could be obtained by using the recently produced Hamamatsu photomultiplier tubes. The knowledge of the pixel scintillation light distribution at photocathode allows the imaging performances optimization. To this aim CsI(Tl) arrays pixel light distributions were investigated by using a photographic method and a Hamamatsu multianode 16 channel linear array photomultiplier tube for single-event light output readout. Ten scintillating arrays, with square pixel base area ranging between 1.0×1.0 and 2.0×2.0 mm2 and thickness from 1.0 to 5.0 mm, were tested. In this study, the strip scintillation light distribution spread at photocathode was found linearly dependent on the total light guide thickness and crystal-pixel base side.