An integrated endotracheal brachytherapy system: Engineering validation and dosimetric advantages

Conventional bronchial and esophageal applicators, such as the Bonvoisin-Gérard applicator (BGA), are not optimal for tracheal brachytherapy due to uncontrolled positioning. We developed the multichannel tracheal applicator (MTA), a single-use, patient-adapted device designed for integration within standard endotracheal tubes (ETT), offering gravity-independent geometry, customizable dose delivery, and validated ventilation compatibility. The intended clinical applications include recurrent granulation tissue at stent margins and primary tracheal carcinomas.

The study comprised three components: (1) anatomical modeling and device design based on Computed Tomography (CT) datasets from 25 patients; (2) validation of ventilation performance and positional stability using Computer-Aided Design (CAD) computational fluid dynamics (CFD) simulations and bench experiments under controlled ventilation and vibration; and (3) dosimetric evaluation with phantom radiochromic film measurements and treatment planning comparisons between MTA and BGA.

Airflow resistance modeling of MTA within the endotracheal tubes (ETT) showed close agreement with experimental data, with peak inspiratory pressure (PIP) differences <2% and values remaining within clinical safety limits up to 500 mL TV. Simulated motion testing confirmed positional stability (<0.5 mm displacement). Dosimetric evaluation demonstrated 99% agreement between measured and planned dose distributions. Compared to BGA, MTA demonstrated improved conformity and better sparing of organs at risk (OAR).

MTA overcomes key geometric and stability limitations of conventional applicators by enabling precise, customizable dose delivery in the trachea while preserving physiological ventilation under standard conditions. Its validated airflow resistance, positional stability, and dosimetric superiority establish strong proof-of-concept evidence. The validated engineering performance and superior dosimetric characteristics justify progression to early-phase clinical trials to evaluate safety, feasibility, and therapeutic efficacy compared to conventional approaches.