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A Monte Carlo simulation of a 50 mm × 50 mm × 4 mm continuous crystal has been developed to investigate the correlation between the scintillation light width (σ) and the Depth of Interaction (DoI) within the crystal. Our studies are based on a LaBr3(Ce) crystal, in order to take advantage of its high light yield to reduce the statistic uncertainties on the estimators of the σ. The first one, the standard deviation of the light distribution, has demonstrated a poor, though linear, correlation to DoI, that is not experimentally detectable. Otherwise, the second estimator, N I , is the ratio of the total number of photoelectrons to the maximum number of photoelectrons collected from a single anode, in a scintillation event. N I has been found to have the best correlation to DoI, that provides 2 mm resolution.

The principal limiting factor in the clinical acceptance of scintimammography is certainly its low sensitivity for cancers sized

The aim of this work is to present a 64-independent channels, low noise and wide dynamic range readout system for multi-anodes photo-multiplier tubes (MA-PMTs). The results consist of some imaging tests obtained with a Hamamatsu H8500 MA-PMT coupled to different scintillation crystals, like a LaBr3(Ce) continuous crystal and NaI(Tl), CsI(Tl) and YAP pixilated scintillation arrays. Moreover, the Hamamatsu H8500C-Mod8 new series equipped with a super bialkali (SBA) photocatode was also studied. Energy and spatial resolutions showed an improvement with respect to the previous generation of multi-channel read-out electronics and we also reported some very interesting results with LaBr3(Ce) crystal coupled to the new Hamamatsu H8500-Mod8 with high quantum efficiency. That demonstrated the excellent response characteristics and versatility of our proposed electronic system and its potential use with all γ-ray detectors.

We have developed a tomograph for single photon emission imaging (SPECT) of the breast for the detection of small size tumors. The SPECT is mounted on a ring that is rotating around the breast with the patient in prone position. The breast will be imaged by two opposing detector heads of approximately 5 × 15 cm 2 each, with a field of view about 13 cm wide. Each head is made up of one pixilated NaI crystal matrix coupled to three Hamamatsu H8500 PMTs. A “general purpose” lead collimator is positioned in front of the crystal. Detailed simulations have been made for the optimization and the evaluation of the detector performances. Monte Carlo results indicate that tumors of 8 mm diameter are detectable with a tumor/background uptake ratio of 5:1. The experimental characterization of the detector head is presented. The rotating ring is now being assembled.