Validation of Fully Automated VMAT Plan Generation for Library-Based Plan-of-the-Day Cervical Cancer Radiotherapy

Abstract

PurposeTo develop and validate fully automated generation of VMAT plan-libraries for plan-of-the-day adaptive radiotherapy in locally-advanced cervical cancer.Material and MethodsOur framework for fully automated treatment plan generation (Erasmus-iCycle) was adapted to create dual-arc VMAT treatment plan libraries for cervical cancer patients. For each of 34 patients, automatically generated VMAT plans (autoVMAT) were compared to manually generated, clinically delivered 9-beam IMRT plans (CLINICAL), and to dual-arc VMAT plans generated manually by an expert planner (manVMAT). Furthermore, all plans were benchmarked against 20-beam equi-angular IMRT plans (autoIMRT). For all plans, a PTV coverage of 99.5% by at least 95% of the prescribed dose (46 Gy) had the highest planning priority, followed by minimization of V45Gy for small bowel (SB). Other OARs considered were bladder, rectum, and sigmoid.ResultsAll plans had a highly similar PTV coverage, within the clinical constraints (above). After plan normalizations for exactly equal median PTV doses in corresponding plans, all evaluated OAR parameters in autoVMAT plans were on average lower than in the CLINICAL plans with an average reduction in SB V45Gy of 34.6% (p<0.001). For 41/44 autoVMAT plans, SB V45Gy was lower than for manVMAT (p<0.001, average reduction 30.3%), while SB V15Gy increased by 2.3% (p = 0.011). AutoIMRT reduced SB V45Gy by another 2.7% compared to autoVMAT, while also resulting in a 9.0% reduction in SB V15Gy (p<0.001), but with a prolonged delivery time. Differences between manVMAT and autoVMAT in bladder, rectal and sigmoid doses were ≤ 1%. Improvements in SB dose delivery with autoVMAT instead of manVMAT were higher for empty bladder PTVs compared to full bladder PTVs, due to differences in concavity of the PTVs.ConclusionsQuality of automatically generated VMAT plans was superior to manually generated plans. Automatic VMAT plan generation for cervical cancer has been implemented in our clinical routine. Due to the achieved workload reduction, extension of plan libraries has become feasible.

Statistical Shape Model to Generate a Planning Library for Cervical Adaptive Radiotherapy

“…A c c e p t e d M a n u s c r i p t combined library, including the modeled shapes, would increase the workload of the physicist at the planning (2h per plan optimization). However, the need for adaptive strategies, based on the generation of multiple treatment plans, is largely accepted and some clinical tools, such as automatic planning tools [41], may ease their clinical implementation. Two ongoing clinical trials based on the use of the planning library showed that 3 to 15 min is required to select the plan-of-the-day at each treatment fraction [10,42].…”

First fully automated planning solution for robotic radiosurgery – comparison with automatically planned volumetric arc therapy for prostate cancer

“…In this work, we have developed the first system for automatic generation of deliverable plans for non-coplanar robotic treatment (autoROBOT). Basis of the autoROBOT planning system is a multi-criterial optimizer that was also the core of a recently developed system for automatic VMAT plan generation for C-arm linacs [19,27]. The developed autoROBOT planning system was first evaluated by comparing manually generated prostate SBRT plans with autoROBOT plans.…”

Evaluation of a simplified optimizer for MR‐guided adaptive RT in case of pancreatic cancer

“…Alternative approaches have been recently developed for delivery systems whose optimization algorithms do not allow adaptive online replanning procedures. The most common strategy consist of creating offline treatment plans libraries in which different possible scenarios are collected (e.g., different filling of hollow organs at risk), allowing the user to choose online the plan that fits the best with the anatomy of the day …”