Optimal approaches to intensity-modulated proton therapy planning and delivery for liver cancer

Purpose To provide practical guidance on different intensity-modulated proton therapy (IMPT) treatment options for liver carcinoma. Methods and Materials This represents a three-institution collaborative consensus effort including radiation oncologists and medical physicists to detail best treatment approaches and recommendations for liver carcinoma cases treated with proton therapy and the approaches used. Results We describe the following cases: 1) 15-fraction IMPT for ∼10 cm HCC IMPT 2) 5-fraction IMPT for ∼10 cm HCC, and 3) spatially fractionated IMPT then 15-fraction IMPT for ∼5 cm oligometastasis. The treatment approach taken for each case is detailed, including immobilization, simulation, treatment planning, target and organ at risk metrics, patient quality assurance, and image guidance for treatment. Additionally, given that technology availability differs from institution to institution, consensus acceptable alternative approaches in clinical management for each case are presented. Conclusions Optimal IMPT approaches for liver treatment are presented that provide the radiation oncology community reference cases and varying technical approaches with which to guide an expanding role of IMPT for this disease site.