Improved SSS-PQS heptahedron block development for low-cost-ultra-high resolution MuPET

Objectives To built a low-cost/high-performance MD Anderson Murine PET (MUPET) detector system.

Methods The detector system consist of a zero gap ring with 180 PQS-SSS blocks. Each block has 13 × 13 crystal array. Edge crystals are 1.76 mm wide, and the inner crystals 1.32 mm wide. Rectangular blocks were ground into heptahedron shaped blocks with a taper angle of 6° on the edge crystals and optical surfaces. We explored the possibility of increasing the detector’s performance by implementing new design, materials, and production techniques; testing the detector’s performance; and measuring the detector’s timing resolution.

Results Heptahedron-detector-block performance: packing fraction,95%; 169 crystal clearly decoded per PMT; peak-to-valley ratio, 2.4; light collection efficiency, 78%; energy resolution, 14% at 511 keV; and averaged (single crystal to block) coincidence timing resolution, 430 ps.

Conclusions Our detector design indicates that it is feasible to construct a high resolution (~1.2 mm) MuPET detector ring using round 19 mm PMTs instead of the more expensive position sensitive PMTs or solid state detectors