Evaluation of patient positional reproducibility on the treatment couch and its impact on dose distribution using rotating gantry system in scanned carbon-ion beam therapy

Purpose The daily variations in patient setup may cause beam range uncertainties. We evaluated the reproducibility of relative position between the patient and the treatment couch throughout the treatment course and assessed its effects on dose distributions when a beam passes through treatment couch using rotating gantry system. Methods We enrolled 1023 patients (=13072 fractions) treated by carbon-ion pencil beam scanning therapy. Seven...