BLUE RIBBON POSTER MULTI-DISCIPLINARY: Enhancing Radionuclide Retention In Phosphorus-32 Plesiobrachytherapy Using Chemically Active Silica–Silicone Composites
Abstract
Purpose
To develop and characterize a flexible silica-silicone composite incorporating phosphoric acid-impregnated silica to improve phosphorus-32 immobilization and leachability control for plesiobrachytherapy applications.
Methods
Silica particles were impregnated with phosphoric acid to promote chemical interaction between phosphorus species and the silica surface. The impregnated silica was incorporated into a silicone elastomer matrix at three different concentrations (5%, 10%, and 15% w/w). Composite matrices were prepared under controlled conditions and cured into reproducible geometries suitable for plesiobrachytherapy sources. Visual inspection and mass variation analyses were performed to assess macroscopic homogeneity, dimensional stability, and reproducibility among samples. Mechanical conformity was qualitatively evaluated through bending and manual handling tests simulating clinical positioning on curved anatomical surfaces. Leachability assays were conducted by immersing the samples in isotonic saline solution at controlled temperature, with aliquots collected at predefined time intervals. Released activity was quantified using calibrated radiation detection systems, and leachability values were calculated following the methodology established in ISO 9978.
Results
All formulations exhibited good flexibility and structural integrity, allowing adaptation to non-planar anatomical surfaces without fracture or loss of integrity. Leachability results for all compositions complied with the acceptance criteria defined by ISO 9978, with improved radionuclide retention observed as silica concentration increased. No swelling, cracking, or visible degradation of the composite matrix was observed during immersion or repeated mechanical handling.
Conclusion
The proposed silica–silicone composite demonstrated compliant leachability behavior, effective radionuclide immobilization, and mechanical conformity compatible with clinical handling requirements. These characteristics support its potential application as a safe and adaptable phosphorus-32 plesiobrachytherapy source for spinal palliative treatments and reinforce the relevance of chemically assisted immobilization strategies for beta-emitting brachytherapy materials in medical physics.