Knowledge-Based Planning as a Real Time Review Quality Assurance Feedback Tool in the TROG 1501 SPARK Trial

Abstract

Quality assurance (QA) in radiotherapy (RT) clinical trials is essential to ensure protocol compliance, patient safety and trial quality. However, protocol compliance does not necessarily ensure optimal plan generation. This study aimed to demonstrate the feasibility and impact of Knowledge-Based Planning (KBP) feedback as part of the Real Time Review (RTR) process for the TROG 1501 SPARK trial (Stereotactic Prostate Adaptive RT Utilising Kilovoltage Intrafraction Monitoring). A knowledge based dose-volume histogram (DVH) estimation model and automated planning routine were created using 34 SPARK RT plans that had previously been submitted as part of the TROG QA program. The KBP routine was applied to 5 subsequent patients pre-treatment. A feedback report comparing the KBP generated DVH versus the initial plan was collated using a customised script and sent to the site within 24 hours. Centres were asked to review the report and decide whether they would amend their clinical plan. Of the 5 patients, 4 were protocol compliant and 1 case was replanned due to a major protocol deviation. As a result of KBP feedback 2/4 (50%) cases which were originally protocol compliant, were nevertheless replanned. Protocol dose constraints for all 5 cases were calculated and an average for each metric was generated. The mean dose-volume metrics were then compared between the initial submission, resubmission and KBP generated plans. Overall, the rectum, bladder, penile bulb and urethra planning risk volume (PRV) demonstrated that an improved dose-volume relationship could be achieved compared to the initial submission and was implemented in practice for the 3 resubmitted cases. Variable results were observed for the femoral heads, demonstrating a potential dose trade off (Table 1).Abstract TU_36_3254: Table 1Organ at Risk (OAR)ConstraintInitial N=5KBP N=5Initial (Resubmitted) N=3Resubmitted N = 3RectumV18.13Gy ≤50%21.6 (15.5 - 29.3)12.7 (8.8 – 20.9)23.1 (15.5 – 29.3)15.0 (10.8 – 19.2)V32.63Gy ≤5%2.6 (0.4 - 4.9)1.7 (0.0 – 3.9)2.0 (0.4 – 4.6)1.4 (0.1 – 3.1)BladderV18.13Gy ≤50%15.6 (3.5 - 29.6)14.7 (4.4 – 32.2)21.1 (16.1 – 29.6)19.5 (9.4 – 32.4)V32.63Gy ≤10%4.7 (0.9 - 8.5)4.8 (1.0 – 10.4)5.8 (3.6 – 8.5)5.4 (2.0 – 9.1)Urethra PRVD0.1cc ≤38.78Gy37.6 (37.1 - 37.9)37.0 (36.6 – 37.7)37.4 (37.1 – 37.5)37.2 (37.0 – 37.5)Penile BulbD0.1cc ≤36.25Gy13.4 (3.7 - 25.3)12.2 (3.5 – 21.5)14.4 (4.9 – 25.3)12.1 (6.3 – 20.1)Left FemHeadD0.1cc ≤30Gy15.5 (12.1 – 17.3)15.6 (13.6 – 17.5)14.8 (12.1 – 16.5)16.7 (14.3 – 20.0)Right FemHeadD0.1cc ≤30Gy16.2 (14.3 – 18.1)16.8 (14.4 – 20.1)16.2 (14.3 – 18.1)18.4 (13.5 – 21.5) Open table in a new tab KBP feedback was successfully incorporated into the RTR process for the SPARK trial and demonstrated that both improvements to and validation of plan quality for OAR dosimetry could be achieved. Further prospective investigation of the role of KBP in TROG clinical trials is planned.