BrachyAtlas: Patient-Specific Virtual Planning for Intracavitary Cesium-131 Brachytherapy with Tile Placement, Dose Calculation, and Modeled Neuroanatomical Exposure

Background: Brachytherapy delivers localized radiation from sources placed within or adjacent to tissue at risk. In brain tumor surgery, intracavitary implantation can begin at resection and concentrate dose along the cavity wall, where many recurrences arise. Current preoperative GammaTile tools estimate tile requirements but not patient-specific placement, resulting dose, or adjacent anatomy. We developed an integrated software framework for patient-specific virtual GammaTile planning. Methods: The framework incorporates AI-assisted tumor and cavity segmentation with user approval, converts accepted masks into patient-derived surfaces, supports virtual tile placement, calculates lifetime Cs-131 dose using TG-43, maps dose distributions to HCP-MMP cortical parcels and normative HCP-1065 white-matter bundles, and supports AI-assisted synthesis of the resulting complex anatomical and connectomic output for clinician review. We retrospectively applied it to three patients with glioblastoma. Tile requirements were compared with the GammaTile Cavity Surface Area Calculator. For Patient 1, calculated 60- and 80-Gy volumes were compared with the clinical plan. Results: Preoperative layouts required 6.5, 7, and 4 tile equivalents for Patients 1-3; calculator estimates were higher by 1.5, 4, and 1 tiles. Postoperative differences narrowed to 1, 1, and 0 tiles. The plans generated patient-specific lifetime dose distributions at 60, 80, and [≥]120 Gy. In Patient 1, calculated and clinical 60- and 80-Gy volumes were similar despite incomplete spatial overlap. Atlas mapping revealed distinct cortical and white-matter exposure patterns across cases beyond lobar description. Conclusions: Patient-specific virtual GammaTile planning can connect anticipated tile placement with calculated dose and adjacent neuroanatomy. These cases demonstrate feasibility and establish a framework for prospective validation and future comparison of candidate implant arrangements.