Quality Assurance in the Dummy Run of a Multicenter Randomized Trial of POstmastectomy radioThErapy in Node-posiTive breast cancer with or without Internal mAmmary nodaL irradiation (POTENTIAL)

Abstract

<h3>Purpose/Objective(s)</h3> To present the results of the dummy run of POTENTIAL (Clinical trials.gov identifier NCT04320979), a multicenter phase III randomized study, investigating the compliance to the protocol guidelines of participating institutes and evaluating the effect of quality control programs in improving interinstitutional consistency. <h3>Materials/Methods</h3> Prior to protocol activation, all the participating institutes were asked to make a treatment plan for a breast patient with Internal mammary nodal (IMN) irradiation according to the protocol of the trial. CT images and outlines of the target volumes and the organs at risk (OAR) are provided by sponsor in Dicom-RT. The plan quality was evaluated by trail QA committee based on dose distribution, dose volume histogram (DVH) and field parameters, etc. After evaluation, recommendations for improvement of the plan quality would be forwarded to participants if a plan revision was required. Thereafter, dose verifications were completed to ensure the accuracy of treatment delivery. <h3>Results</h3> A number of deviations from trail protocol were observed by plan review. The average D95% of the CW and the IMN target volume were approximately 10% lower than prescribed dose for the conventional fractionation group (50 Gy in 25 fractions) and 3% for the hypofractionation group (43.5 Gy in 15 fractions). After revision, the dose coverage of the targets was significantly improved. The average D95% of the CW and the IMN target volume reached higher than 49 Gy and 43 Gy for the conventional fractionation group and the hypofractionation group, respectively. The revised plans also provided better OAR dose sparing. <h3>Conclusion</h3> The QA program in the dummy run had a positive effect in improving interinstitutional consistency, since the deviations from trail protocol were significantly decreased by plan review and revision.