A new method of anatomically conformal vaginal Cuff HDR brachytherapy

Abstract

Objective HDR brachytherapy to the vaginal cuff using rigid intracavitary cylinders has a limited capacity to adapt to patient-specific anatomy. This study describes the use and dosimetry of a new method of anatomically conformal post-operative vaginal cuff HDR brachytherapy using an intra-vaginal balloon applicator. Methods Thirty consecutive patients with endometrial carcinoma underwent a hysterectomy and received adjuvant HDR brachytherapy in 6 weekly fractions using an intra-vaginal balloon. Optimal distension of the balloon to conform to the vaginal cuff was clinically determined to achieve complete balloon surface apposition with the vaginal mucosa and was confirmed radiographically. Radiation dose was prescribed to the vaginal mucosa and brachytherapy CT simulation was performed to optimize the irradiation dose in 3-D. Results 180 brachytherapy procedures were performed. The mean volume of balloon distension was 47.3 cc (range 20.8–83.8 cc; ± 11.3 cc). The mean dose from brachytherapy to the 2 cc volume of the bladder and rectum was 48.6% and 71.1% of the prescribed vaginal mucosal dose, respectively. Bladder and rectal doses increased as a function of balloon volume. 100% of the prescribed dose covered an average of 95.6% of the vaginal cuff. There were no acute complications or vaginal cuff recurrences at a mean follow-up of 13 months. Conclusions Post-operative vaginal cuff HDR brachytherapy using an intra-vaginal balloon applicator which conforms to the individual patient's vaginal cuff provides excellent radiation dose coverage of the vaginal mucosa with acceptable doses to the bladder and rectum.