SU‐D‐BRC‐02: Application of Six Sigma Approach to Improve the Efficiency of Patient‐Specific QA in Proton Therapy

Abstract

Purpose:To show how the Six Sigma DMAIC (Define‐Measure‐Analyze‐Improve‐Control) can be used for improving and optimizing the efficiency of patient‐specific QA process by designing site‐specific range tolerances.Methods:The Six Sigma tools (process flow diagram, cause and effect, capability analysis, Pareto chart, and control chart) were utilized to determine the steps that need focus for improving the patient‐specific QA process. The patient‐specific range QA plans were selected according to 7 treatment site groups, a total of 1437 cases. The process capability index, Cpm was used to guide the tolerance design of patient site‐specific range. We also analyzed the financial impact of this project.Results:Our results suggested that the patient range measurements were non‐capable at the current tolerance level of ±1 mm in clinical proton plans. The optimized tolerances were calculated for treatment sites. Control charts for the patient QA time were constructed to compare QA time before and after the new tolerances were implemented. It is found that overall processing time was decreased by 24.3% after establishing new site‐specific range tolerances. The QA failure for whole process in proton therapy would lead up to a 46% increase in total cost. This result can also predict how costs are affected by changes in adopting the tolerance design.Conclusion:We often believe that the quality and performance of proton therapy can easily be improved by merely tightening some or all of its tolerance requirements. This can become costly, however, and it is not necessarily a guarantee of better performance. The tolerance design is not a task to be undertaken without careful thought. The Six Sigma DMAIC can be used to improve the QA process by setting optimized tolerances. When tolerance design is optimized, the quality is reasonably balanced with time and cost demands.