Failure mode and effects analysis for errors detected during pretreatment physics plan and chart review in external beam radiotherapy

Background: Quality assurance (QA) plays a critical role in patient safety during radiation therapy. Among various QA checks, pretreatment physics plan review is sensitive at detecting errors before beam delivery. Therefore, we aimed to assess the errors detected during pretreatment physics plan and chart review (PTPCR) through a failure mode and effects analysis (FMEA) and to evaluate the quality and effectiveness of the PTPCR performed at our clinic. Methods: Five qualified medical physicists used a single checklist to perform a total of 1,406 PTPCRs in 2019. Five major PTPCR process steps were reviewed: (I) planning parameters, (II) plan quality, (III) image parameters, (IV) MOSAIQ management, and (V) chart documents. Errors detected during the PTPCR were identified to failure modes (FMs) in each process step. A risk priority number (RPN) was assigned to each FM based on tabulated scores for the severity (S), frequency of occurrence (O), and detectability (D) of errors, each on a scale of 1 to 10. The single error rate, multiple error rate, and overall error rate were calculated to evaluate the quality of the treatment planning. The PTPCR compliance rate was used to quantify the effectiveness of the PTPCR. Results: In total, 201 errors were identified from the 1,406 plans. From the FMEA results, image parameters had the highest mean RPN, and the planning parameters had the highest RPN from the FM of skin flash. The chart documents had the highest number of FMs and highest occurrence rate, followed by MOSAIQ management and planning parameters. The average single, multiple, and overall error rates were 10.6%, 1.3%, and 11.9%, respectively. The PTPCR compliance rate was 90.3%. Conclusions: The FMEA provided a systematic and useful method for evaluating the errors detected in the PTPCR. The compliance rate could help us understand the effectiveness of our PTPCR. The FMEA results and the PTPCR compliance rate could help us improve our PTPCR to ensure the safety of treatment and the efficiency of the clinical workflow.