Abstract
PURPOSE/OBJECTIVES: Currently, ocular disease is primarily managed with COMS plaque brachytherapy. Various stereotactic radiosurgery (SRS) platforms have also been employed, yet widespread access remains a challenge. Herein, we demonstrate the feasibility of using the HyperArc SRS system to provide an additional platform for the treatment of ocular malignancies. MATERIALS/METHODS: Twenty previously treated COMS patients with ocular melanoma were selected for a retrospective HyperArc SRS planning study. The average gross tumor volume (GTV) derived from MRI was 1.19 ± 0.60 cc. Planning target volumes (PTV) were generated from a 2 mm expansion of the GTVs. HyperArc plans were created for a TrueBeam LINAC (6MV-FFF) with the Encompass support system and used the AcurosXB algorithm for dose calculation. A dose of 25 Gy was prescribed to the PTVs and all plans were normalized such that PTVD95% = 25 Gy. All organs at risk (OARs) were spared adequately. Patient-specific quality assurance (QA) and an independent Monte Carlo (MC) second check was performed for all SRS plans. RESULTS: HyperArc plans demonstrated high conformality Paddick conformity index (PCI = 0.84 ± 0.04) with steep dose gradient index (GI = 3.29 ± 0.38). Compared to the HyTEC standard (12.1 Gy), it adequately spared the optic nerve(s) (Dmax = 7.18 ± 1.26 Gy, p < 0.001). Adequate PTV coverage (D99% = 23.80 ± 0.46 Gy) was achieved with a mean GTV dose of 27.54 ± 0.47 Gy. Maximum dose to critical OARs were controlled: brain (6.00 ± 1.50 Gy), optic nerve (7.18 ± 1.26 Gy), and ipsilateral lens (9.36 ± 5.67 Gy). Average beam-on time was under 9 min. End-to-end QA results showed a 99.00 ± 0.59% pass rate (2%/2 mm γ-criteria), with a MC check showing 97.81 ± 1.24% agreement with the AcurosXB algorithm (2%/2 mm). CONCLUSION: HyperArc SRS plans provided adequate target coverage, acceptable OARs sparing, and offer a fast, safe, and non-invasive treatment option for ocular tumors. Clinical implementation of this novel methodology is ongoing at our institution.