Akademik Veri Yönetim Sistemi
Acıbadem Üniversitesi Sağlık Bilimleri Dergisi, cilt.16, sa.4, ss.560-566, 2025 (Hakemli Dergi)
ABSTRACT
Purpose: In this study, we explored how automated HyperArc (HA) planning performs compared to manually designed
VMAT plans in treating patients with multiple brain metastases.
Materials and Methods: Ten patients with an average of 15 brain metastases (range: 10–23) were retrospectively
analyzed. All patients had undergone high-resolution CT imaging (1mm slice thickness) registered to contrast-enhanced
MR sequences. Target delineation was performed by a radiation oncologist. For lesions ≥10 mm, the gross tumor volume
(GTV) was equal to the planning target volume (PTV), while for smaller lesions, a 1mm isotropic margin was added. VMAT
plans were generated using a single isocenter with non-coplanar arcs, while HA plans were retrospectively created with
automated optimization. Prescribed doses ranged from 20 to 30 Gy, delivered in 3–5 fractions. The dosimetric parameters
compared included conformity index (CI), gradient index (GI), homogeneity index (HI), healthy brain V10Gy and V12Gy
volumes, maximum and median doses to the brainstem, and maximum doses to the optic chiasm, optic nerves, eyes, and
lenses. Total monitor unit (MU) values were also evaluated.
Results: Target coverage was similar between VMAT and HA plans, with no statistically significant differences in CI
(p = 0.721) or GI (p = 0.241). HA plans showed a trend toward increased dose homogeneity. Notably, HA significantly
reduced the dose to healthy brain tissue, with V10Gy and median brain doses lower compared to VMAT. Critical structures,
including the brainstem (p = 0.009), optic chiasm (p = 0.013), and lenses, also received lower doses with HA. In addition, HA
plans required approximately 65% fewer monitor units than VMAT (p = 0.007), indicating a shorter treatment delivery time.
Conclusion: In patients with ten or more brain metastases, HA provided more favorable dosimetric outcomes for healthy
brain tissue and organs at risk, while also improving treatment efficiency. These findings suggest that HA planning can
deliver high-quality SRS plans with reduced dependence on manual optimization, making it a promising approach for
complex multi-target cases.
Keywords:Hyperarc, VMAT, Multiple brain metastases, stereotactic radiosurgery