PMT based pentagonal and hexagonal detector module designs for convex polyhedron PET systems

Our previous studies indicated that convex polyhedron PETs, such as dodecahedral PET, are able to achieve high performances similar to those of S-PETs. A convex polyhedron PET consisting of a couple of flat detectors is much easier to be constructed compared to an S-PET that needs detectors with curved surfaces. Typical convex polyhedrons suitable for PET include the dodecahedron (a regular convex polyhedron with 12 regular pentagonal faces) and the truncated icosahedron (an Archimedean solid with 12 regular pentagonal faces and 20 regular hexagonal faces). In both situations, pentagon-shaped and/or hexagon-shaped detector modules, instead of conventional square-shaped block detector module, are required. We presented two conceptual pentagonal detectors and two conceptual hexagonal detectors based on conventional lost-cost PMT-light-sharing scheme. Monte Carlo simulations were performed to investigate the crystal decoding performances of all four designs. The results show that high quality flood map can be archived by (1) increasing the areas of the PMT layer and (2) applying a light guide with optimized thickness in the detector modules. We conclude that that it is feasible to design and implement low-cost pentagonal or hexagonal detector modules for the convex polyhedron PETs.