Systematic Implementation of Effective Quality Assurance Processes for the Assessment of Radiation Target Volumes in Head and Neck Cancer

Abstract

<h3>Purpose/Objective(s)</h3> Target volume delineation and treatment planning in Radiation Oncology for head and neck cancer (HNC) cases can be challenging and time consuming. Volume delineation requires significant expertise and is subject to significant inter-physician variability, and changes in treatment volumes after planning has started are associated with planning delays. While chart rounds are a major quality assurance (QA) intervention for treatment planning, few strategies have been developed to effectively evaluate volume delineation. The aim of the study is to evaluate the feasibility, effectiveness and the potential clinical impact of implementation of prospective Quality Assurance (QA) Processes for the assessment of radiation target volumes. <h3>Materials/Methods</h3> Starting in 2020, a systematic weekly QA process with real-time metrics was adopted in our department for the assessment of HNC planning target volumes (PTVs) before the start of radiation planning. All definitive-intent treatment cases (intact and post-operative) were evaluated. Contours were flagged with green (none), yellow (minor), or red colors (major) based on the degree of required modifications. <h3>Results</h3> 400 consecutive HNC cases were included. A total of 37 (9%) PTVs required modifications, 5 (1%) of these were flagged as red (major) deemed highly likely to impact oncologic outcomes – for example, omission of gross disease and/or elective areas at high risk of microscopic disease. Thirty-two (8%) were flagged yellow (minor) deemed potentially to impact oncologic or functional outcomes—for example, omission of elective areas at intermediate or low risk of harboring microscopic disease, or errors of over-contouring volumes into normal critical structures. All contouring modifications were performed before the start of radiation planning, resulting in significant reduction in the amount of re-planning by our dosimetry group and zero delays in treatment start due to planning within this cohort. Interestingly, between the first 200 and second 200 HNC cases reviewed, major modifications decreased from 5 to 0 and minor modifications from 22 to 10 (chi squared p=0.02), suggesting the presence of a learning curve and standardization of practice of the treating physicians even at a high-volume academic center. <h3>Conclusion</h3> Our study highlights the feasibility and importance of systematic contour QA in head and neck radiation oncology. Further evaluation and implementation of these efforts across other disease sites appear warranted.