Analysis of EORTC-1219-DAHANCA-29 trial plans demonstrates the potential of knowledge-based planning to provide patient-specific treatment plan quality assurance

Introduction: Radiotherapy treatment plan quality can influence clinical trial outcomes and general QA may not identify suboptimal organ-at-risk (OAR) sparing. We retrospectively performed patient-specific quality assurance (QA) of 100 head-and-neck cancer (HNC) plans from the EORTC-1219-DAHANCA-29 study. Materials and methods: A 177-patient RapidPlan (Varian Medical Systems) model comprising institutional HNC plans was used to QA trial plans (Ptrial). RapidPlan plans (Prapidplan) were created using RapidPlan and Eclipse scripting to achieve a high degree of automation. Comparison between Prapidplan mean predicted/achieved OAR doses, and Ptrial mean OAR doses was made for parotid/submandibular glands (PGs/SMGs) and swallowing muscles (SM). Results: OAR predictions were made within 2 min per patient. Averaged PG/SMG/SM mean doses were 2.0/9.0/3.8 Gy lower in Prapidplan. Using predicted Prapidplan combined mean OAR dose as the benchmark, a total of 60/27/4 trial plans could be improved by 3/6/9 Gy respectively. Discussion: Individualized QA indicated that OAR sparing could frequently be improved in EORTC-1219 study plans, even though they met the trial's generic plan criteria. Automated, patient-specific QA can be performed within a few minutes and should be considered to reduce the influence of planning variation on trial outcomes.