A Dosimetric Comparison of HyperArc Therapy Planning and Volumetric Modulated Arc Therapy Planning in Treating Patients With Glioblastoma Multiforme.

Background/aim: This study aimed at evaluating the potential benefit of automatic non-coplanar volumetric arc therapy (VMAT) (hyperarc, HA) technique in treating glioblastoma multiforme (GBM).

Patients and methods: Twenty-seven patients with GBM who received coplanar VMAT (C-VMAT) were selected in this study. HA and non-coplanar VMAT (NC-VMAT) plans were generated with the same prescriptions and constraints. The Target coverage, organs at risk (OARs) dose, and dosimetric indexes were compared among three plans.

Results: The HA plan demonstrated a reduction in dose to normal tissues while maintaining target coverage, compared to C-VMAT and NC-VMAT. Additionally, HA plans demonstrated higher coverage of the GTV and PTV₆₀ as well as improved CI from PTV₆₀ and PTV₄₆ compared to the other plans. Regarding the dose gradient, HA plans showed a greater dose fall-off, resulting in reduced high-dose and intermediate-dose spillage at PTV₄₆ The HA also demonstrated a tighter gradient radius at PTV₆₀ and PTV₄₆ The HA plan requires fewer MUs than both C-VMAT and NC-VMAT.

Conclusion: The HA plan had better dosimetric results compared to C-VMAT and NC-VMAT. The HA with automatic planning module and auto-delivery treatment also provided high-quality planning and delivery efficacy. These advantages suggest that HA could potentially escalate tumor doses while minimizing toxicity, thereby improving outcomes in GBM patients.