Fully automatic volumetric modulated arc therapy plan generation for rectal cancer

Background and purpose: To develop and evaluate a fully automatic rectal planning optimizer (ARPO) for volumetric modulated arc therapy (VMAT) treatment planning without human interaction. Materials and methods: The ARPO was developed using inherent Pinnacle(3) script language; it was designed to perform the whole planning process including planning structure generation, beam placement, doseline setting and treatment planning. The automatic scheme adjusts the objectives of the objective function simulating the operation of dosimetrists based on our clinical experience. A total of 29 planned rectal cancer patients were retrospectively replanned using the ARPO (VMAT(auto)) under the same constraints. Results: With the ARPO, the hands-on time required for the whole planning process was significantly reduced to <1 min. All VMAT(auto) plans were recognized as clinically acceptable and 69% as clinically improved; 3% of VMAT(auto) plans were marked equal and 28% inferior to manually generated VMAT(man) plans when reviewed in a single-blind study by one experienced radiation oncologist. Without any planning workload the VMAT(auto) plans had similar planning target volume dose coverage to the VMAT(man) plans and statistically better organ-at-risk sparing, especially regarding lower small intestine irradiation. Conclusions: The ARPO is robust and dramatically efficient in clinical application and provides improved planning quality. (C) 2016 Elsevier Ireland Ltd. All rights reserved.