3D-printed vaginal cylindrical template with curved needle channels in MRI-guided vaginal cuff brachytherapy.

Purpose: To present a new technique for the treatment of vaginal cuff recurrences using 3D-printed vaginal cylindrical template (3D-PVCT) with curved needle channels in brachytherapy. Material and methods: Two patients with vaginal cuff tumor treated with external beam radiotherapy and MRI-guided interstitial brachytherapy were selected for the present study. Prior to treatment, a vaginal cylinder with the same size as 3D-PVCT was inserted into the vagina. Magnetic resonance scan was performed to identify target volumes and organs at risk (OARs). By registration techniques, the implantation angle was determined, appropriate needle channels were selected, and the depth of each needle position was recorded. During the actual treatment, patients were under general anesthesia, and real-time guidance of trans-rectal ultrasound was applied referring to a pre-determined treatment plan. Results: For patient No. 1, 9 needles were inserted into the tumor, with 4 curved needle channels and 5 straight channels. For patient No. 2, 7 needles were inserted into the vaginal cuff tumor, with 6 curved needle channels and 1 straight channel. Doses delivered to volumes of targets and OARs for both patients met the EMBRACE II dose constraints. After follow-up of 15 and 18 months, respectively, both patients showed complete response, with no evidence of tumor recurrence. No significant acute or late toxicities were reported. Conclusions: With careful pre-planning, 3D-PVCT provides good target coverage and sparing of OARs. The results from these two patients indicate that this approach is very promising due to its flexibility and potential widespread application in the future.