Robust Optimization for Intensity-Modulated Proton Therapy to Redistribute High Linear Energy Transfer (LET) from Nearby Critical Organs to Tumors in Head and Neck Cancer

Abstract Purpose We propose linear-energy-transfer (LET)-guided robust optimization in intensity-modulated proton therapy (IMPT) for head-and-neck (HN brainstem LETmax: 10.95 vs. 12.05, p=0.0007; oral cavity LETmean: 2.11 vs. 3.12, p=0.0052], and had comparable physical dose and plan robustness in all OARs. In the worst-case scenario, LETRO achieved significantly higher LETmean in CTV, reduced LETmax in brain, and comparable other LETVH indices [CTV LETmean: 3.26 vs. 3.35, p=0.0012; brain LETmax: 24.80 vs. 22.00, p=0.0016]. Conclusions LETRO robustly optimized LET and physical dose distributions simultaneously. It redistributed high LET from OARs to targets with slightly modified physical dose and plan robustness.