PG production yield enhancement for facilitating in-vivo proton beam range verification

Regardless of the Prompt Gamma (PG) technique being used to monitor the range of proton beam in vivo, the low PG statistics detected entangle the efficiency of their clinical implementation. We propose a new technique for PG production yield enhancement by inducing a non-radioactive element in the tumor area. This would potentially optimize the detection of the PG characteristic peaks of 4.44 MeV and 6.13 MeV resulting from ¹²C* and ¹⁶O* de-excitations respectively, and help in proton range verification in-vivo. The elements tested were¹⁹F, ¹⁷O,¹²C, and ¹H. We simulated via the Tool for Particle Simulations (TOPAS) Monte Carlo (MC) package, the interaction of 75 MeV incident proton beam in a concentric cylindrical geometry; the outer cylinder was filled with water and the inner cylinder was filled with water and 0.01%-25% fraction in weight of the candidate elements. We identified the PG characteristic peaks in the spectrum, and then we assessed the PG enhancement for the different material concentrations. All tested elements led to a PG production yield enhancement by 15-16% and up to 4% for the 4.44 MeV and 6.15 MeV PG peak accordingly. Simulations with different materials and assessment of probable toxicity induced from the enhancers to the organ at risks are in progress.