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/spl times/22 mm/sup 2/) while M16 has a 4/spl times/4 anode array with an active area of 18/spl times/18 mm/sup 2/. 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/spl times/1.5 mm/sup 2/ and 4.2/spl times/4.2 mm/sup 2/ to compare the imaging properties.