Experience-Based Quality Control in Radiation Therapy Treatment Planning of High Risk Post-prostatectomy Prostate Cancer with RapidPlan: NRG Oncology RTOG 0621

Abstract

To develop a knowledge based planning (KBP) model with RapidPlan (Varian Medical Systems, Palo Alto, USA) for the treatment of high risk post-prostatectomy prostate cancer using a knowledge database of high quality treatment plans from the national clinical trial RTOG 0621. To test the model as a quality assurance (QA) tool and use it to establish the feasibility of the compliance criteria for NRG GU003. :An initial dosimetric analysis was carried out to identify high quality treatment plans from RTOG 0621. Treatment plans for patients enrolled in the trial were scored according to the system used by the Imaging and Radiation Oncology Core (IROC) of the National Clinical Trials Network (NCTN) of the NCI to assess adherence to the trial protocol. Of the 80 treatment plans enrolled in the trial a knowledge database of 40 high quality plans was used to train the model. Another subset of plans, orthogonal to the training set, was chosen for the validation set to ensure that the model accurately predicts dose volume histograms (DVHs) for all critical structures. The remaining plans were re-optimized with the model in order to test its effectiveness as a QA tool. The re-optimized plans were analyzed to determine what percentage pass each of the compliance criteria for NRG GU003. The RapidPlan prostate model has been successfully trained and used to re-optimize plans selected from RTOG 0621. Plans re-optimized with the model show increased dose sparing to the bladder and rectum without loss of target coverage. These re-optimized plans show a reduction of V50 of up to 45% for the bladder and 24% for the rectum when compared with the original clinical plans submitted to the trial. The RapidPlan prostate model developed in this study is an effective tool for IMRT treatment planning QA.