Exhibit Hall | Forum 7
Purpose: The automated non-coplanar planning technique (HyperArc), originally intended for cranial treatments, has been shown superior to conventional planning methods for dose escalation in head and neck (HNC) radiotherapy. This study aims to evaluate the dosimetric benefits of HyperArc for various HNC treatment sites with standard dose prescriptions.
Methods: A total of 35 SBRT and fractionated HNC plans treated between June 2020 and February 2022 were analyzed. In all cases, a HyperArc plan and a traditional VMAT plan were created with the same dose prescription and planning constraints, and the attending physician selected one plan best suited for treatment. The plans were evaluated based on the following factors: conformity, OAR sparing, target coverage, and treatment delivery time. A variety of treatment sites were included in this cohort: larynx, mandible, maxilla, neck, oral cavity, orbit, parotid gland, sinus, and thyroid.
Results: In 30 of the 35 total cases, the HyperArc plan was chosen for treatment over the traditional VMAT plan. HyperArc plans were preferred in these cases because of improved conformity (20%), better OAR sparing (16.67%), better target coverage (16.67%), or a combination of these reasons (46.67%). In instances where the conventional plans were chosen for treatment, reasons included improved conformity (20%), better OAR sparing (60%), and shorter delivery time (20%). Neither target size nor treatment site were found to be clinical indicators of the selection of the treatment plan.
Conclusion: HyperArc plans were chosen by the treating physician over traditional VMAT plans in more than 85% of cases, demonstrating clinically relevant dosimetric benefits of automated non-coplanar VMAT for a broad population of HNC patients. The majority of these plans were preferred for clinical treatment due to a combination of improved conformity, OAR sparing, and target coverage.
Funding Support, Disclosures, and Conflict of Interest: This study was funded by Varian. One author is a consultant for ViewRay Inc.