KEY POINTS
- This technical note developed a structured workflow for VMAT-based lattice spatially fractionated radiation therapy across Edge TrueBeam and Halcyon linacs using Eclipse Acuros v16 and 6 MV flattening filter-free beams.
- The implementation included 28 preliminary phantom/test plans, 12 representative clinical test plans across head and neck, pelvis-abdomen, and extremity sites, and 6 lung plans evaluating respiratory motion effects.
- Two prescription strategies were tested: 18 Gy × 1 to vertices with valley dose <6 Gy, and a simultaneous integrated boost approach delivering 66.7 Gy to vertices with 20 Gy in 5 fractions to the whole target.
- Point-based peak-to-valley dose ratios ranged from approximately 2.8 to 3.4 across platforms and prescriptions; Delta4 and EPID gamma pass rates exceeded 90% using 3%/1 mm criteria.
- Respiratory motion of about 5 mm reduced point-based peak-to-valley dose ratio by approximately 25% in evaluated lung cases and changed organ-at-risk doses, supporting motion-managed imaging and target definition.
CLINICAL TAKEAWAY
This study provides a practical commissioning and QA roadmap for VMAT-based lattice SFRT rather than fixed universal planning parameters. The main message is that comparable lattice dose heterogeneity can be achieved on both Edge and Halcyon, but platform-specific MLC geometry, vertex spacing, plan modulation, and motion management matter. The evidence is technical and institution-dependent, so centers should treat this as an implementation framework requiring local validation, not a plug-and-play clinical standard.