Dose-Summation–Guided Re-irradiation Planning for Brain Metastases: Cross-Platform Verification Between Brainlab Elements and GammaPl

We report a practical, cross-platform workflow for cumulative-dose-aware re-irradiation in brain metastases. Before RT-DOSE is imported across planning systems (Brainlab Elements and/or GammaPlan), previously irradiated foci are treated prospectively as organs-at-risk during optimization, and the summed dose is visualized to avoid hotspots while preserving coverage. In a verification case planned without dose summation, a non-target previously irradiated focus ultimately developed radiation necrosis; post-hoc summation showed that explicit constraints could have reduced cumulative exposure. In a second case prospectively planned with summation, target coverage was maintained while decreasing the unintended dose to a non-target previously treated focus, with subsequent control and no new toxicity. This cross-platform approach is feasible and clinically actionable for balancing efficacy and safety during repeat stereotactic radiosurgery near prior high-dose regions.