High Resolution Imaging System (HiRIS) based on H9500 PSPMT

The H8500 PhotoMultiplier Tube (PMT) from Hamamatsu has been used in the last years to assemble several scintigraphic devices in order to achieve high-resolution gamma cameras. If the detector is coupled to discrete scintillator with millimetric pixel size, the resulting charge distribution that emerges is not properly sampled by its anodes (6×6 mm2). The new position sensitive PMT H9500, with its 3×3 mm2 anodes, allows a better charge distribution sampling, improving both spatial resolution and linearity of the system. In this paper, we investigate the imaging performances of the H9500 PMT coupled with a CsI(Tl) array having 1 mm pixel size and compare the results with the same scintillator coupled with H8500 PMT. A portable imaging system named HiRIS (High-Resolution Imaging System) was then realized using a miniaturized readout electronic. Thanks to its lightness, it can be easily used in Medical Imaging. We used HiRIS, together with a rotating system, to carry out a tomographic reconstruction of the biodistribution of a radiopharmaceutical in rats.