Optimization of catheter placement for interstitial gynecological brachytherapy with centroidal Voronoi tessellation

To evaluate the feasibility of using images taken after placement of the Template and APPlicator (post-TAPP) with a geometry-based catheter placement optimization to generate interstitial implants in locally advanced cervical cancer cases.

A processing pipeline with Centroidal Voronoi Tessellation (CVT)-based catheter optimization was used to retrospectively simulate optimized catheters on post-TAPP imaging from 32 cervix transperinneal interstitial brachytherapy cases using a Syed Neblett template (16 with iterative MR-guidance, 16 without). Treatment plans were generated with CVT-optimized and clinically implanted catheters. Improvement in plan quality and decrease in number of inserted catheters due to catheter optimization were evaluated against cases performed with and without intraoperative MR imaging.

Use of CVT resulted in fewer unused catheters (mean reduction of ∼3) compared to the clinical cases performed both with and without MR imaging guidance, without an increase in %V₁₅₀ or %V₂₀₀. In non-MR-guided cases, use of CVT improved the EMBRACE-II limit compliance for D_90% for CTV_HR. This improvement was not observed in MR-guided procedures.

This feasibility study suggests that post-TAPP CVT catheter optimization can achieve clinically acceptable dosimetry while limiting unnecessary catheters, showing a qualitative improvement in dosimetry compared to using preBrachy images alone for catheter selection.