Iranian Biomedical Journal

other Multiphysics Simulation of the Synergistic Interaction Between Plasma-Based Radiosensitization and Liquid 131Cs Balloon Brachytherapy in GBM Related Fields Related Fields کنگره Congress <div style="text-align: justify;">Introduction: Glioblastoma multiforme (GBM) is a highly aggressive primary brain tumor known for its significant resistance to radiation treatment. This resistance is primarily due to efficient repair of DNA double-strand break (DSB), hypoxic microenvironments (with oxygen partial pressure, pO₂ < 10 mmHg), and hypermethylation of the MGMT promoter. Standard treatment typically involves maximal safe surgical resection, external beam radiotherapy (60 Gy/30 fractions), and the chemotherapy agent temozolomide, providing a median survival of only 14.6 months. To enhance the cytotoxic effects of ionizing radiation on residual tumor cells within a 1 cm clinical target volume, this study employs a multiphysics simulation that integrates plasma-based radiosensitization with liquid 131Cs balloon brachytherapy. Materials and Methods: The photon transport from a silicone balloon (0.2 mm wall thickness, 3 cm diameter) filled with liquid 131Cs (half-life = 9.7 days, energy ≈ 29 keV) was modeled using Using MCNPX 2.6. This model aims to deliver 60 Gy at a distance of 1 cm from the balloon its surface (with V₁₀₀ = 92%, D₉₀ = 58 Gy, and BED₁₀ < 100 Gy). Additionally, COMSOL Multiphysics 6.2 simulated an argon dielectric-barrier discharge (10 kV, 10 kHz, 0.1 L/min for 60 seconds) producing reactive oxygen species (ROS) and nitrogen species such as O₃, •OH, H₂O₂, and nitric oxide, with penetration depths of 1.2–1.8 mm and <10% deviation from experimental validation. Results and Discussion: Linear-quadratic modeling (α₀ = 0.25Gy⁻¹, β = 0.03Gy⁻²) that incorporated CAP-induced α enhancement (Δα/α₀ = 28%) predicted a 37% reduction in survival of U87MG cell (SF(combined) = 0.15 vs. 0.24) and a 35% increase in apoptosis, as indicated by γ-H2AX and caspase-3 activation. Plasma-activated liquids (PAL) further improved the diffusion of ROS by ~50% without inducing significant thermal effects (ΔT < 1.5°C). Overall, CAP and PAL act as effective radiosensitizers, amplifying oxidative damage to DSB and improving the therapeutic efficacy of 131Cs brachytherapy while maintaining safe doses of normal tissue. Conclusion: Our findings support the development of a hybrid intraoperative treatment system and its future preclinical application in trials.  </div>   <table align="center" border="1" cellpadding="0" cellspacing="0"> <tbody> <tr> <td></td> <td><img alt="" height="84" src="./files/site1/images/Picture1.jpg" width="507" ></td> <td></td> </tr> </tbody> </table> 131Cs balloon brachytherapy, Cold atmospheric plasma, COMSOL multiphysics, GBM, MCNPx simulation, Plasma-based radiosensitization 7 7 http://ibj.pasteur.ac.ir/browse.php?a_code=A-10-1-869&slc_lang=other&sid=1 Amir Kazemi Yes Hosein Poorbaygi No Somayeh Akbari Koradeh No