Beschreibung:
<jats:title>Abstract</jats:title><jats:sec><jats:title>Purpose</jats:title><jats:p>Integrating log file analysis with LINACWatch<jats:italic>®</jats:italic> (<jats:italic>LW</jats:italic>) into clinical routine as part of the quality assurance (QA) process could be a time‐saving strategy that does not compromise on quality. The purpose is to determine the error sensitivity of log file analysis using LINACWatch<jats:italic>®</jats:italic> compared with a measurement device (ArcCHECK<jats:italic>®, AC</jats:italic>) for VMAT delivery QA.</jats:p></jats:sec><jats:sec><jats:title>Materials and methods</jats:title><jats:p>Multi‐leaf collimator (MLC) errors, collimator angle errors, MLC shift errors and dose errors were inserted to analyze error detection sensitivity. A total of 36 plans were manipulated with different magnitudes of errors. The gamma index protocols for AC were 3%/3 mm/Global and 2%/2 mm/Global, as well as 2%/2 mm/Global, and 1.5%/1.5 mm/Global for LW. Additionally, deviations of the collimator and monitor units between TPS and log file were calculated as RMS values. A 0.125 cm<jats:sup>3</jats:sup> ionization chamber was used to independently examine the effect on dose.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>The sensitivity for AC was 20.4% and 49.6% vs 63.0% and 86.5% for LW, depending on the analysis protocol. For MLC opening and closing errors, the detection rate was 19.0% and 47.7% for AC vs 50.5% and 75.5% for LW. For MLC shift errors, it was 29.6% and 66.7% for AC vs 66.7% and 83.3% for LW. AC could detect 25.0% and 44.4% of all collimator errors. Log file analysis detected all collimator errors using 1° detection level. 13.2% and 42.4% of all dose errors were detected by AC vs 59.0% and 92.4% for LW using gamma analysis. Using RMS value, all dose errors were detected by LW (1% detection level).</jats:p></jats:sec><jats:sec><jats:title>Conclusion</jats:title><jats:p>The results of this study clearly show that log file analysis is an excellent complement to phantom‐based delivery QA of VMAT plans. We recommend a 1.5%/1.5 mm/Global criteria for log file‐based gamma calculations. Log file analysis was implemented successfully in our clinical routine for VMAT delivery QA.</jats:p></jats:sec>