Validity of one‐time phantomless patient‐specific quality assurance in proton therapy with regard to the reproducibility of beam delivery

The log file records of plan-relevant spot parameters are well-reproducible over multiple fractions and deviations have no dosimetrically relevant impact on the reconstructed fraction doses. Results of a one-time pre-treatment LFQA are considered as valid for the entire treatment course and there is no concern in this regard to replace state-of-the-art phantom measurements in the current PSQA workflow.