Ensemble RBE Modeling in Proton Therapy: A Meta-Synthesis Framework for Dose Assessment in the Brainstem and Spinal...

IntroductionProton therapy minimizes damage to healthy tissues while effectively targeting tumors. However, uncertainties in relative biological effectiveness (RBE) calculations remain a challenge, particularly for critical organs at risk (OARs), such as the brainstem and spinal cord. This study introduces ensemble RBE models (eRBE-B and eRBE-SC) developed through a meta-synthesis (MS) approach to improve dose accuracy and stability in proton radiotherapy.Materials and MethodsA systematic literature review following PRISMA guidelines identified studies utilizing variable RBE models. The MS approach aggregates data on model usage patterns and study quality due to the lack of direct RBE measurements. Three primary models (Carabe, Wedenberg, and McNamara) were weighted on the basis of study quality and case counts to construct ensemble RBE models. Dose calculations and analysis were performed via RayStation 8B, MCsquare, and 3D Slicer.ResultsCompared with the Carabe model, the eRBE-B model resulted in reduced dose underestimation, with mean dose ($D_{Mean}$) and maximum dose ($D_{\mathrm{Max}}$) differences of -0.89 Gy (-1.44%) and -1.08 Gy (-1.61%), respectively. For the brainstem, eRBE-B closely aligned with the McNamara model, yielding $D_{Mean}$ and $D_{\mathrm{Max}}$ values of 9.88 Gy and 64.07 Gy, respectively. Ensemble models demonstrated enhanced consistency and stability across critical OARs, mitigating biases inherent in single-model approaches.ConclusionEnsemble RBE models offer a robust alternative to standalone models in proton therapy. By aggregating published RBE data, the MS approach enhances dose precision for critical organs, improving the safety and efficacy of proton radiotherapy. These findings underscore the potential of computational tools to optimize treatment planning for head and neck cancer patients.