Evaluation of Hamamatsu H13974 Large Sensitive Area Flat Panel PMT Array for Use in Small Animal Imaging and Scintimammography

In this paper, we report for the first time on the performance of the Hamamatsu H13974 flat panel photomultiplier tube (PMT) array. This new photodetector is based on four Hamamatsu H12700A position sensitive PMTs in a $ 2 \times 2$ arrangement providing large sensitive area ( $ {100\times 100}$ mm 2 ) for use in scintimammography or/and medium size mammals imaging. We acquired raw images from three pixellated scintillators for possible positron emission tomography and single photon emission computed tomography applications (BGO with $ {2\times 2\times 6}$ mm 3 , CsI:Tl with $ {2\times 2\times 4}$ mm 3 , and CsI:Na with $ {1.45\times 1.45\times 6}$ mm 3 pixel sizes) irradiated with 511 keV ( 68 Ga) and 140 keV ( 99 m Tc), respectively. Different coupling schemes involving optical grease and optical glasses of different thicknesses were used in order to find the scheme that better resolves the crystal elements of the scintillators especially in the dead areas of the flat panel PMT array. We present the results of investigating the basic properties, including energy resolution, intrinsic spatial resolution, detection efficiency, and sensitivity uniformity. The scintillation material, the coupling scheme and the analog readout circuits are the main factors that affect the performance of the detector. The proper combination of these factors should be carefully chosen so as to build a high performance imaging system.