Enhanced 3D-GRID Radiotherapy on Helical Tomotherapy Via Personalized Geometric Optimization: A Comparative Study of IMRT and VMAT
Abstract
Purpose
This study aimed to develop and evaluate a personalized, geometrically optimized 3DGRID radiotherapy strategy using Helical Tomotherapy (TOMO), designed to maximize tumor ablation while preserving surrounding organs at risk (OARs). We systematically compared its dosimetric characteristics and delivery efffciency against IMRT and VMAT
Methods
Fifteen patients with large-volume tumors (GTV > 150 cm3) were retrospectively analyzed. A novel algorithm was employed to generate individualized cylindrical 3D-GRID structures, optimizing their geometric distribution based on tumor morphology and OAR anatomy. Treatment plans were created using TOMO, IMRT, and VMAT. Key dosimetric parameters for GTV and OARs, conformity index (CI), ablative volume fraction (AVF), and peak-to-valley dose ratio (PVDR), alongside delivery times, were then compared.
Results
The automated algorithm successfully generated consistent cylindrical GRID structures for all patients. Dosimetrically, TOMO demonstrated high feasibility, achieving target coverage (D2%: 66.26 ± 1.77 Gy) and an AVF strictly comparable to VMAT (AVF range: 2.03%−2.25%, p = 0.950), with both signiffcantly superior to IMRT (p 0.05).
Conclusion
Personalized geometric optimization of 3D-GRID radiotherapy on Helical Tomotherapy is feasible and offers a compelling alternative for spatially fractionated radiation therapy. This approach effectively balances high target ablative volume, superior dose heterogeneity (PVDR), and enhanced OAR protection, overcoming limitations of traditional lattice techniques on TOMO. While VMAT remains the most efffcient modality, TOMO, when employing this optimized 3D-GRID strategy, provides comparable dosimetric outcomes, making it a viable option for maximizing biological effectiveness, especially when treatment time is a less critical factor.