3D Printed Surface Applicators for High Dose Rate Brachytherapy

Abstract

HDR surface mould brachytherapy is a technique used to treat various types of skin lesions including basal and squamous cell carcinoma. This work investigates the feasibility of using 3D printed surface applicators for the treatment of HDR brachytherapy. An extensive phantom study was conducted to assess various treatment locations on the body, including the ankle and the nose. 3D printed applicators were digitally designed and customized using the existing patient CT set. Radiation plans were generated for two applicator types: Freiburg Flap and 3D printed. Within the plan, critical target volumes (CTVs) and organs-at-risk (OARs) were contoured to analyze the quality of the plan created by the two applicator modalities by studying their respective dosimetric properties obtained from a dose-volume histogram (DVH). Due to the inverse square properties of the source, we also were concerned with the air gaps between the applicator and the skin. We found that the radiation plans for the 3D printed applicator yielded comparable or better dose distributions compared to Freiburg Flap applicators, with notable improvements on the nose study. The volume of air gaps between applicator and skin also dropped 98% and 58% for the ankle and nose study, respectively. These findings have allowed us to begin using 3D printed applicators for patients within the clinic receiving HDR brachytherapy for treatment of the skin.