Dynamic Time-Over-Threshold Readout for Improved Energy Linearity in PET Detectors that Achieve 100 ps CTR

We have embedded a dynamic time-over-threshold (DynTOT) block in our scalable TOF-PET detector readout electronics to linearize the multiplexed energy spectra while keeping 100 ps FWHM Coincidence Time Resolution (CTR) performance. This DynTOT block is constructed by off-the-shelve components and consumes only 20 mW power per detector ‘layer’ in our design. Using 3×3×10 mm³ "LGSO" crystals coupled to arrays of 3×3 mm² SiPMs, energy resolution of 13.8±0.1%, 13.9±0.3%, and 17.1±0.6% were experimentally achieved for conventional pulse height, DynTOT, and conventional TOT methods, respectively. Including the DynTOT method, coincidence data were experimentally acquired using a low jitter FPGA-based TDC, and 103.6 ± 1.1 ps FWHM CTR was achieved, demonstrating the robustness of our novel and scalable timing electronic chain.