Lower-cost Depth-of-Interaction PET Detector Designs Using Dichotomous-3D Decoding

A "Dichotomous-3D" DOI PET detector design approach is proposed. The approach can potentially reduce the production cost of incorporating Depth-of-Interaction (DOI) in PET systems because the photo-sensors usage and electronic complexity would be even less than that of the current non-DOI PET detectors. The "Dichotomous-3D" approach can be implemented in two ways: (a) the Dichotomous-Offset-Quadrant-Sharing design (DO-QS) which is deterministic and has good timing resolution for time-of-flight (TOF) PET, and (b) the Dichotomous-Orthogonal-Symmetric light-channel DOI design which would reduce the SiPM and electronics usage even more but the time resolution may be degraded for TOF; however, it can be used for building a low-cost high-sensitivity BGO PET with a long axial-field-of-view. Preliminary Monte Carlo simulations for both designs have been performed to gauge the feasibility. The Monte Carlo simulation results show that both proposed designs are feasible with a DOI resolution of 4 to 5 mm depending on the crystal materials and geometry. The DO-QS DOI detector design can also unambiguously decode nine 1x1 mm(2) crystal pixels using the much larger standard 3x3 mm(2) SiPM for building ultrahigh-resolution brain PET and animal PET with nine crystals coupling to one SiPM, thereby reducing the SiPM usage and supporting electronics by 9 times.