Applying 3D-Printed Templates in High-Dose-Rate Brachytherapy for Cervix Cancer: Simplified Needle Insertion for Optimized Dosimetry.

Purpose: In cervical cancer brachytherapy, adding interstitial needles to intracavitary applicators can enhance dosimetry by improving target coverage while limiting normal tissue dose. However, its use is limited to a subset of practitioners with appropriate technical skill. We designed tandem anchored radially guiding interstitial templates (TARGITs) with a 3-dimensional (3D) printing workflow to optimize needle placement and facilitate greater ease-of-use of intracavitary/interstitial (IC/IS) technique. This study compared dosimetry and procedure characteristics between tandem and ovoid (T&O) implants using TARGIT technique versus non-TARGIT technique.
Methods and Materials: This single-institution retrospective cohort study included patients undergoing T&O brachytherapy as part of definitive radiation treatment for cervical cancer between February 2017 and January 2021. TARGIT technique was implemented from November 2019 onwards; all prior procedures involved non-TARGIT technique using a no needle or freehand needle approach. Target coverage, dose to organs at risk, and procedure times were evaluated and compared between TARGIT technique and non-TARGIT technique.
Results: The cohort included 70 patients with cervical cancer who underwent 302 T&O procedures: 68 (23%) with TARGIT technique and 234 (77%) with non-TARGIT technique, which included 133 no needle and 101 freehand needle implants. TARGIT implants involved longer average procedure times (+6.3 minutes, P < .0001). TARGIT implants achieved a higher mean high-risk clinical target volume V100% than non-TARGIT implants (+4.4%, P = .001), including for large tumors 30 cm ³ or greater (+8.1%, P = .002). Average D90 was 4.6 Gy higher and average D98 was 3.2 Gy higher for TARGIT technique compared with non-TARGIT technique (P = .006 and P = .02). Total treatment doses to rectum, bowel, and bladder were not significantly different for TARGIT versus non-TARGIT technique.
Conclusions: The 3D-printed TARGIT approach to T&O brachytherapy achieved greater tumor coverage while sparing normal tissues, particularly for large tumor volumes, with only a slight increase in average procedure time. TARGIT represents a creative technological solution for increasing accessibility of advanced IC/IS brachytherapy technique for cervical cancer definitive radiation treatment.
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