Proof-of-Concept for Intraoperative Dosimetry Assessment of Gammatile Placement Using Intraoperative MRI and 3D Slicer Software
Abstract
Purpose
GammaTile cesium-131 collagen tiles provide immediate postoperative radiation therapy for brain tumors by lining the resection cavity, delivering a steep dose fall-off to target residual disease while sparing healthy tissue. However, intraoperative verification of tile placement and dose coverage remains challenging due to limited real-time tools. We developed and tested a proof-of-concept method for real-time dosimetry assessment during GammaTile placement in the operating room (OR) using a retrospective intraoperative MRI (iMRI) integrated with open-source 3D Slicer software.
Methods
Under IRB-approved retrospective study STUDY00010486, post-resection iMRI scans (T1-weighted sequences optimal for cavity visualization) from a clinical case was analyzed. Images were imported into 3D Slicer for simulated tile positions. A prototype approach modeled fixed 4-seed Cs-131 geometry per tile, applied TG-43-based dose calculations (or simplified point-source models), and generated 3D dose distributions and isodose lines. Drag-and-drop, tile rotation/translations, and dragging features were implemented for real-time adjustment in both 2D and 3D visualizations. Processing time and feasibility for potential intraoperative adaptation were assessed.
Results
Retrospective application to initial clinical case demonstrated efficient iMRI import, ability to drop tiles in the cavity, and dose computation within 5-10 minutes. Underdosed or overlapped regions could be visualized, highlighting potential intra-operative opportunities for refinement. Compared to conventional post-procedure verification, this workflow could provide enhanced dosimetric insight into intraoperative decisions, with qualitative improvements in coverage assessment.
Conclusion
This retrospective proof-of-concept confirms the feasibility of using iMRI and 3D Slicer for GammaTile dosimetry evaluation, offering a low-cost, open-source framework for real-time intra-operative dosimetry. Translation to prospective real-time intraoperative use could improve placement accuracy and patient outcomes; additional prospective validation and advanced TG-43 integration are needed for clinical implementation.