A Semi-Automated Robotic Platform for Curvilinear Catheter Implantation in HDR Prostate and GYN Brachytherapy

High-dose-rate (HDR) brachytherapy is an effective treatment for prostate and gynecologic cancers, yet current rigid catheter systems constrain trajectories to straight paths, limiting conformity to patient-specific anatomy and compromising dose distribution. To address this, we developed and preliminarily evaluated a semi-automated robotic platform for curvilinear catheter implantation. The system integrates (i) a handheld tendon-driven active needle manipulator with joystick-based control, (ii) an innovative template for initial angulation, and (iii) a novel gynecologic applicator incorporating concentric tube robotics for steerable tandem delivery. Patient-specific curvilinear trajectories were preplanned from anonymized MRI/CT datasets, and experimental evaluations were conducted in air and tissue-mimicking phantoms. The handheld manipulator achieved tip displacement errors below 2.89 mm in air and 2.22 mm in phantom, while the combined device-template system reproduced prostate curvilinear trajectories with root mean squared deviations (RMSDs) under 3.67 mm. Integration of the concentric tube robot with the gynecologic applicator achieved uterine trajectories with RMSDs below 1.17 mm. These results demonstrate, for the first time, the feasibility of semi-automated active needle manipulation and concentric tube-assisted applicator design for anatomically conformal HDR brachytherapy. This approach has the potential to improve catheter placement accuracy, enable patient-specific dose escalation, and reduce toxicity to organs at risk in both prostate and cervical cancer treatment.