Session Item

Vaginal-cuff brachytherapy is the adjuvant treatment in women with intermediate to high risk endometrial cancer or uterine cervical cancer. The most commonly used applicators are single-channel vaginal cylinder and two-symmetric ovoid applicators according to the shape of the stump. For two-ovoid applicators, the distance between the ovoid applicators depends on the therapist and vaginal size. The greater the distance, the less dose appears in the vaginal apex point. To overcome the problem, the aim of this study is to propose the brachytherapy planning using three-ovoid applicators to improve insufficient dose distribution.

Clinical dosimetry was calculated using HDRPlus software and the patient was treated using the BEBIG MultiSource® High Dose Rate brachytherapy treatment unit with a cobalt-60 source. In this study, three types of applicators (cylinder, two-ovoid, and three-ovoid applicators) were used, and three brachytherapy plans were compared for optimal dose delivery. The three-ovoid applicators are two-ovoids and tandem with multiple holding discs. In accordance with American Brachytherapy Society guidelines, the total treatment dose is 5Gy in 5 separate fractions. For each individualized treatment planning, dose optimization was performed in a standardized plan according to the applicator types. To compare the three brachytherapy plans, prescription point, vaginal apex point, bladder, and rectal dose were evaluated. The dose at the vaginal apex point, which was defined as 5 mm above the surface of the vaginal apex corresponding to the midline of the applicator tips and perpendicular to the anteroposterior axis of the patient, was calculated.

In the planning using cylinder, two-ovoid, and three-ovoid applicators, the calculated values for the vaginal apex point are 4.40 Gy, 2.18 Gy, and 4.68 Gy, respectively. These values correspond to 88%, 43.7%, and 93.7% of the prescribed dose, respectively. The bladder doses are 3.69 Gy, 1.35 Gy, and 3.63 Gy, respectively. The rectal doses ranged from 1.0-4.8 Gy, 1.1-2.3 Gy, and 1.8-5.3 Gy, respectively.

We confirmed the feasibility of a vaginal-cuff brachytherapy planning using three-ovoid applicators to deliver optimal dose distribution leading to better clinical outcomes.