Investigation of a Dual-Panel In-Beam PET Based on Digital Detectors for Proton Therapy Monitoring With Different Monitoring Strategies: A Simulation Study

In-beam positron emission tomography (PET) has shown great potential as a technology for proton therapy monitoring. Our group has developed a compact all-digital PET detector with high coincidence time resolution and energy resolution. Based on this detector, this study investigated the feasibility of a dual-panel in-beam PET (DiB-PET) system for proton therapy monitoring through Monte Carlo simulations. We designed a single-field treatment plan for an intracranial tumor and investigated three monitoring strategies: (1) monitoring the range of a single spot, (2) monitoring the range of a single midenergy layer, and (3) monitoring the range of a single-field plan. We introduced range deviations by varying the soft tissue density and evaluated the range verification accuracy by quantifying the linear relationship between activity range shift and dose range shift. With 120-second PET acquisition, DiB-PET achieved an average range verification accuracy of approximately 1.0 mm. This accuracy was consistent across all three monitoring strategies: on a spot-by-spot basis for both a single spot and a single mid-energy layer, as well as on a voxel-by-voxel basis for a single-field plan. These findings highlight DiB-PET’s high sensitivity and versatility, demonstrating its feasibility for proton therapy monitoring.