Simulation of a low-Z-medium detector for low-dose high-resolution TOF-PET

Two major challenges in time-of-flight positron emission tomography (TOF-PET) are low spatial resolution and high radioactive dose to the patient, both of which result from limitations in detection technology rather than fundamental physics. A new type of TOF-PET detector employing low-atomic number (low-Z) scintillation media and large-area, high-resolution photodetectors to record Compton scattering locations in the detector has been proposed as a promising alternative, but neither a direct comparison to state-of-the-art TOF-PET nor the minimum technical requirements for such a system have yet been established. Here we present a simulation study evaluating the potential of a proposed low-Z detection medium, linear alkylbenzene (LAB) doped with a switchable molecular recorder, for next-generation TOF-PET detection. We developed a custom Monte Carlo simulation of full-body TOF-PET using the TOPAS Geant4 software package. By quantifying contributions and tradeoffs for energy, spatial, and timing resolution of the detector, we show that a reasonable combination of specifications improves TOF-PET sensitivity by more than 5x, with comparable or better spatial resolution and 40-50% enhanced contrast-to-noise as compared to state-of-the-art scintillating crystal materials. These improvements enable clear imaging of a brain phantom simulated at less than 1% of a standard radiotracer dose, which could enable expanded access and new clinical applications for TOF-PET.