Dosimetric evaluation of a novel automated noncoplanar volumetric modulated arc therapy technique for treating optic nerve sheath meningiomas

Zhenyu Xiong; Chingyun Cheng; Lili Zhou; Brett Eckroate; Loren Bell; Fredrick Warburton; David Huang; Sabin B Motwani; Charles S Cathcart; Ke Nie; Ning Yue; Yin Zhang

doi:10.3389/fonc.2025.1531918

Dosimetric evaluation of a novel automated noncoplanar volumetric modulated arc therapy technique for treating optic nerve sheath meningiomas

Front Oncol. 2025 Jun 27:15:1531918. doi: 10.3389/fonc.2025.1531918. eCollection 2025.

Authors

Zhenyu Xiong^{1

2

3}, Chingyun Cheng⁴, Lili Zhou³, Brett Eckroate^{1

2

3}, Loren Bell³, Fredrick Warburton³, David Huang³, Sabin B Motwani^{2

3}, Charles S Cathcart³, Ke Nie^{1

2

3}, Ning Yue^{1

2

3}, Yin Zhang^{1

2

3}

Affiliations

¹ Department of Radiation Oncology, Rutgers Cancer Institute of New Jersey, Rutgers, The State University of New Jersey, New Brunswick, NJ, United States.
² Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, New Brunswick, NJ, United States.
³ Department of Radiation Oncology, RWJBarnabas Health, West Orange, NJ, United States.
⁴ Department of Human Oncology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, United States.

Abstract

Purpose: This study aimed to evaluate the dosimetric outcomes for the target and organs at risk (OARs) in patients with optic nerve sheath meningiomas (ONSMs), comparing HyperArc (HA), a novel automated noncoplanar volumetric modulated arc therapy (VMAT) technique, with two other advanced VMAT techniques.

Methods: Nine patients with ONSMs were re-planned using three radiotherapy techniques: HA employing four preconfigured noncoplanar partial arcs on the Varian TrueBeam, a two-arc coplanar VMAT on the Varian TrueBeam (TB-VMAT), and a two-arc coplanar VMAT on the Varian Halcyon (HAL-VMAT). All treatment plans aimed to deliver 50.4 Gy in 28 fractions to the planning target volume (PTV) while minimizing dose to OARs. The planning process began by applying identical preset optimization templates for each plan, followed by iterative refinements of objectives and priorities to accommodate individual plan requirements. All plans were normalized to ensure that 100% of the prescription dose covered 95% of the PTV. Dosimetric evaluation included PTV metrics (D_98%, D_mean, D_max, and D_min), the Paddick Conformity Index (PCI), the International Commission on Radiation Units and Measurements Report 83 (ICRU-83) homogeneity index (HI), the gradient index (GI), and doses to OARs for each technique. Statistical significance was assessed using the Wilcoxon signed-rank test with a p-value threshold of < 0.05.

Results: HA plans demonstrated superior dosimetric indices for PTV, as indicated by the highest D_98% (50.24 ± 0.05 Gy) and the lowest D_max (53.20 ± 0.23 Gy), HI (0.04 ± 0.00), and GI (3.56 ± 0.58) values (p < 0.05). These results indicated superior target coverage and a more homogeneous dose distribution. Furthermore, HA plans achieved the lowest maximum dose values for the following OARs: lenses, hippocampi, contralateral optic nerve, and contralateral retina (p < 0.05), thereby optimally sparing these critical structures. No significant differences were observed across techniques regarding D_mean, D_min, PCI, or maximum dose to the ipsilateral optic nerve, ipsilateral retina, and optic chiasm.

Conclusions: HA plans demonstrated superior dosimetric performance, ensuring adequate target coverage, reduced PTV hotspots, and better OAR protection compared to coplanar VMAT plans on the Varian TrueBeam and Halcyon. These advantages suggest that.

Keywords: HyperArc; dosimetric comparison; optic nerve sheath meningioma; radiotherapy; volumetric modulated arc therapy.