Imaging properties evaluation of compact PSPMTs for discrete gamma cameras application

Hamamatsu Photonics has recently developed a new generation of compact Position Sensitive PhotoMultiplier Tubes (PSPMT) based on metal channel dynode charge multiplication technology. R5900 family has now a range of compact tubes mainly differing for the anode structure. The models considered here, C8 and M16, also differ for active photocathode area. C8 has a crossed plate anode configuration consisting of 4X+4Y stripes and a larger active area (22×22 mm²) while M16 has a 4×4 anode array with an active area of 18×18 mm² . Here, the authors report their evaluation of C8 and M16 for clinical imaging applications as hand held probe, multi-PSPMT camera and tomographic ring. To this aim measurements of pulse linearity, positioning response, inter-channel gain variation and anodes cross talk were performed using a light source coupled to a 1 mm diameter optical fiber. Finally PSPMTs were optically coupled to 5 CsI(Tl) scintillating arrays with pixel size ranging between 1.5×1.5 mm² and 4.2×4.2 mm² to compare the imaging properties