Customized Vaginal Vault Brachytherapy With CT Imaging-derived Applicator Prototyping

Abstract

Conventional cylindrical intracavitary brachytherapy applicators do not conform to individual vaginal conformation. Irregular, fibrotic, or tethered tissue result in suboptimal dosimetry when treated with standard applictors5. The technique presented here enables the physical creation of a patient specific applicator with embedded optimized catheter trajectories. The curved catheter trajectories employed cannot be created and optimized using any other standard manufacturing process available today. In this example case, this design effectively treat a wide irregular vaginal apex, while simultaneously achieving relatively narrow dose distribution in the anterior/posterior directions, directly translating to relative rectal and bladder sparing. Clinically, early vaginal edema may occur after the first fraction, therefore an allowance for tissue expansion was recognized in adapting the 3-D model to the physical applicator. Rapid-prototyping offers a feasible alternative to inflatable intracavitary applicators6 or interstitial brachytherapy techniques. The design of applicators is no longer constrained by standard 2D manufacturing process, and can eliminate the need for mould room resources.