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

Purpose: 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.

Methods and materials: 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_HR) and organs at risk (OARs). To evaluate the optimality of the DIP-based configurations, DVH parameters were assessed after changing the number of catheters.

Results: The DIP workflow was successfully established. Compared to the IP method, the DIP method achieved similar DVH parameters for both CTV_HR and OARs with significantly fewer catheters (p < 0.01). The addition of catheters did not significantly alter DVH parameters, while their reduction significantly compromised CTV_HR coverage (p < 0.01) and increased OAR doses (p < 0.05).

Conclusions: The DIP method enables patient-specific optimization of minimal catheter configurations and supports the broader implementation of high-quality IC/ISBT.