Log file‐based patient‐specific quality assurance for MR‐guided radiation therapy with comprehensive motion management

Vollständiger Abstract

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Abstract Background Patient‐Specific Quality Assurance (PSQA) for Elekta Unity MR‐Linac treatments delivered under Comprehensive Motion Management (CMM) is challenging because beam gating, unexpected interruptions, and split sub‐segments introduce delivery complexities that are not fully addressed by conventional quality assurance workflows. Purpose This study aimed to develop and evaluate a log file‐based PSQA program for Elekta Unity MR‐Linac treatments delivered under CMM. Methods Log files were parsed to extract Multileaf Collimator (MLC) positions, jaw positions, and Monitor Units (MU) for each segment, with dedicated handling of CMM‐induced beam gating, unexpected beam interruptions, and split sub‐segments. Gantry‐resolved fluence maps reconstructed from the log files were compared with planned fluence maps using gamma analysis. The system was evaluated for 66 cases, including 3 completion plans and 2 baseline shift plans. Results Among the 66 plans, 64 achieved passing gamma results, with a pooled average passing rate of 99.91 ± 0.21%. Conclusions The proposed log file‐based PSQA framework demonstrates accuracy and clinical practicality for MR‐Linac treatments in CMM mode. It may serve as a reliable post‐treatment verification tool and reduce dependence on conventional phantom‐based QA.