Dosimetric evaluation of Ethos 2.0 high‐fidelity mode for single‐isocenter SRS

The HFonRon template produced better quality plans, achieving significant improvements in normal tissue sparing (p < 0.0001), CI (p < 0.0001), and Falloff index (p < 0.0001) compared to other templates. All templates provided clinically acceptable target coverage. In the HFoffRoff configuration, 97.5 % of targets met the coverage criterion (V100% > 95%). The other setups achieved coverage in 99.2% (HFoffRon), 96.6% (HFonRoff), and 98.3% (HFonRon) of targets, respectively. Plan complexity decreased significantly (p < 0.0001) when enabling HF mode compared to both HF disabled templates CONCLUSIONS: His study shows that combining Ethos 2.0's high-fidelity mode with user-defined control rings yields superior single-isocenter SRS plans compared with planning strategies that omit one or both features. This approach improves dose conformity, reduces normal tissue exposure, and decreases plan complexity through semi-automated, template-based planning. These findings suggest that HF mode can be a valuable tool in clinical practice for optimizing SRS treatments for patients with brain metastases.