Evaluation of a sub-millimeter resolution PET detector with a 1.2 mm pitch TSV-MPPC array one-to-one coupled to LFS scintillator crystals and individual signal readout

For developing a small animal Positron Emission Tomography (PET) scanner for whole-body imaging of mice, both structures of detector blocks and signal readout scheme are important factors to achieve sub-millimeter spatial resolution. These specifications are crucial for intrinsic spatial resolution. A sub-millimeter resolution PET detector composed of a 1.2 mm pitch MPPC array with TSV structure one-to-one coupled to LFS scintillator crystals has been constructed and evaluated. To evaluate intrinsic spatial resolution, coincidence response functions (CRFs) of the detector pair located parallel to each other at a distance of 80 mm were measured by scanning a 0.25 mm diameter
²²
Na point source with 0.1 mm steps. The data were acquired by the CAMAC system. The average FWHM of the CRFs was 0.751 mm without corrections of the point source size. Additionally, to improve detector efficiency by suppressing the positioning errors, an interaction-order defining algorithm based on Compton kinematics was adapted to the same data, and we consider inter-crystal scatter effects comparing errors arising from the interaction-order defining algorithm and the centroid calculation.