Shinya Komori

Efficient workflow and clinical validation of in-house 3D-printed vaginal cylinders for high-dose-rate brachytherapy for gynecologic malignancies

This study developed an efficient methodology for in-house 3D-printed vaginal cylinders for gynecologic tumor treatment by evaluating their radiation attenuation, geometric accuracy, and efficacy. Ultimately, we aim to establish a simple, cost-effective approach that facilitates broad clinical adoption. Patient-specific vaginal cylinders were designed based on anatomical contours from the treatment planning system (TPS) using CAD software. The process was optimized to minimize manpower and time costs. Radiation attenuation of the 3D printer material was compared with that of water using the Monte Carlo method. Geometric accuracy was automatically analyzed via an in-house MATLAB program. Efficacy was assessed in cases of postoperative vaginal stump recurrence and vaginal cancer with paravaginal invasion. The tumor shape, delineated by TPS, was imported into CAD software, and the catheter pathway model, designed via subtraction processing, was placed at the optimal position and angle. The design process took approximately 15 min, and the entire workflow was completed within a week, demonstrating its practicality for clinical use. The radiation attenuation error was < 3% compared with water, and the geometric accuracy error was < 0.2 mm. The patient-specific vaginal cylinder provided a favorable dose distribution and was effective in complex cases. A feasible workflow was established, allowing in-house design and manufacturing with reduced manpower and time costs. With no material or processing issues, this approach is safe, practical, and promising for widespread adoption in personalized brachytherapy.

A novel dose-based intra-preplan method for high-dose-rate brachytherapy in cervical cancer using modeling and optimization algorithms

This study presents the dose-based intra-preplan (DIP) method for intracavitary/interstitial brachytherapy (IC/ISBT) in cervical cancer, optimizing catheter configurations based on dose distribution. This study aimed to assess the DIP method's clinical feasibility and efficacy. The DIP method incorporates the implant modeling function and the hybrid inverse planning optimization algorithm in Oncentra Brachy. Virtual applicator and catheter models were created and merged with patient-specific computed tomography images. Subsequently, an optimization algorithm was used to automatically determine the optimal catheter configuration-including the number, positions, and insertion depths. The workflow was retrospectively validated in 14 IC/ISBT patients treated with the Geneva applicators. Catheter configurations from the DIP and conventional intra-preplan (IP) methods were compared in terms of catheter number and dose-volume histogram (DVH) parameters for high-risk clinical target volume (CTV The DIP workflow was successfully established. Compared to the IP method, the DIP method achieved similar DVH parameters for both CTV The DIP method enables patient-specific optimization of minimal catheter configurations and supports the broader implementation of high-quality IC/ISBT.