Multicriteria optimization: Site-specific class solutions for VMAT plans

Abstract

Multicriteria optimization (MCO), a novel commercially available optimization method for IMRT and VMAT has the potential to improve treatment planning techniques and workflows. MCO allows planners and physicians to assess in real time the impact and tradeoffs between all clinical goals and organ constraints. We investigate the feasibility of a universal set of objectives and constraints for VMAT plans in different anatomical sites and the impact of involving the Physician in the navigation of the generated Pareto plans. We randomly selected 20 prostate only, 14 whole pelvis, 10 advanced lung, 15 pancreas, and 7 head and neck plans planned with a VMAT technique. Using the clinically delivered isocenter and beam set-up, we retrospectively generated MCO plans with a universal set of constraints and objectives for each anatomical site. The MCO plan scores were compared with clinical plans or an independent plan generated with DMPO. For prostate only plans the TCP values for the clinical and MCO plans were similar and the rectum NTCP values and overall P+ were slightly better for the MCO plans. For whole pelvis, the resulting MCO plans were comparable in all the dosimetric measures to the clinical plans. For lung, the MCO dosimetric comparison also yielded comparable plans but when evaluating individual patients, there were 5 patients for which MCO plans had a clear advantage in reducing dose to lung and/or esophagus while improving/maintaining target coverage, 4 patients with comparable plans and 1 patient where MCO was worse. Allowing the physician to navigate independently produced a different selection of dosimetric trade-offs. Comparable MCO plans were also obtained for pancreas and head and neck. Based on our experience with many anatomical sites and a large number of patient plans, we have found that VMAT MCO plans are comparable to the clinical plans and can be produced with a universal set of objectives and constraints, even for a wide range of geometries and anatomies.