Brachytherapy-based multimodality cancer treatment: a concept and design perspective on devices to address the challenges of localized radiation therapy.

Purpose: To present a family of novel brachytherapy-based device concepts that address the geometric, dosimetric, and integrative limitations of current localized radiation therapy, aiming to improve local tumor control while reducing collateral exposure. This is a concept and design paper, not a clinical or dosimetric validation study. Methods: Multiple device designs were developed over more than a decade, focused on two prototypical clinical settings: intraluminal applicators for the esophagus and intracavitary applicators for the post-resection glioblastoma cavity. Designs include hollow rectangular ribbon (HRR) catheters that encase fluid, gel, or wire isotope sources; modified stents with anti-slippage geometry, dynamic flares, and reservoirs; and a multifunctional cavity device combining brachytherapy with continuous hyperthermia and pressure-modulated diffusional drug, immunotherapy, and nanoparticle delivery. Bench prototypes were constructed and evaluated. Results: Bench observations demonstrated manipulation of a thermal gradient by modulating the warm source, and an approximately 15-fold increase in dislodgement force for a representative anti-slippage geometry. The designs are further intended to flatten the near-surface dose gradient by expanding the effective source distribution and to integrate drainage, infusion, and pressure modulation in a single device; these dosimetric and integrative benefits are design expectations not yet experimentally tested. Conclusion: These concepts may improve local control where recurrence concentrates near the resection or stented surface, as in post-resection glioblastoma and obstructive luminal malignancies. The integration of continuous hyperthermia, local diffusion of chemotherapeutic, immunotherapeutic, and protective agents, and pressure-modulated nanoparticle delivery is particularly attractive. The concepts are intended to stimulate further bench, computational, animal, and clinical investigation.