ESTRO 2025 - Abstract Book

S221

Brachytherapy - Gynaecology

ESTRO 2025

Intermediate Risk (RI) CTV) and organs at risk (bladder, rectum and sigmoid) were defined in conformity with GEC ESTRO recommendations

Results: Nineteen patients with vaginal tumours, including 17 treated with a perineal template, were analyzed. Tumours were primary in 42% of cases and metastatic in 58%, comprising 42% adenocarcinomas and 58% squamous cell carcinomas. All lesions were located in the upper or middle thirds of the vagina. Initial external radiotherapy was administered to all patients, with 63% also receiving concomitant chemotherapy. Ten patients received pulsed dose-rate (PDR) brachytherapy, while nine received high-dose-rate (HDR) treatment. The median number of intracavitary needles was 6 [6; 8.5], with a median of 5 [3; 8] interstitial needles. Median doses were 71.6 Gy EQD2 [70.7; 75.8] at D90 for HR CTV and 62.3 Gy EQD2 [60.8; 66.6] at D90 for IR CTV. Organs at risk had median D2cc doses of 61.4 Gy EQD2 [50.2; 69.5] for the bladder, 59.6 Gy EQD2 [55.9; 63.7] for the rectum, and 47.4 Gy EQD2 [45; 53.1] for the sigmoid. Conclusion: The Venezia® applicator is effective for treating upper and mid-vaginal tumours, i.e at the level of the vaginal cups. Tumours located in the vaginal cuff can be treated with interstitial needle inserted from the two lunar-shaped ovoid template, however midline vaginal fundal tumors are less adequately covered due to the absence of a medial needle insertion. The design of the perineal plate does not permit fixation of needles to the posterior vaginal wall, though manual placement remains feasible if needed. The Venezia applicator enables effective brachytherapy for tumors located in the middle and upper thirds of the vagina, offering MRI-based delineation and achieving dosimetric outcomes consistent with recommended guidelines. Digital Poster Technique, experience and feasibility of hyaluronic acid rectovaginal spacers in MRI-guided gynecological cancer brachytherapy: a prospective study Carminia Lapuz 1,2 , Sylvia Hanna 1 , Eddie Lau 3 , Adeline Lim 1 , Mark Tacey 1 , Jenny Sim 2 , Claire Dempsey 4,5,6 , Daryl Lim Joon 1,2 , Michael Chao 1,2 1 Radiation Oncology, Austin Health, Melbourne, Australia. 2 Medical Imaging and Radiation Sciences, Monash University, Melbourne, Australia. 3 Radiology, Austin Health, Melbourne, Australia. 4 Radiation Oncology, Calvary Mater Newcastle, Newcastle, Australia. 5 Health Sciences, University of Newcastle, Newcastle, Australia. 6 Radiation Oncology, University of Washington, Seattle, USA Purpose/Objective: To evaluate the technique, operator experience, feasibility, and safety of hyaluronic acid (HA) rectovaginal spacers in high dose rate brachytherapy (HDR-BT) for gynecological (GYN) cancers. Material/Methods: Patients diagnosed with GYN cancers planned for treatment with HDR-BT at a single institution were included in this prospective study. All patients received a pre-HDR-BT magnetic resonance imaging (MRI) scan and were planned to receive 3-4 HDR-BT fractions. Under general anesthesia and prior to brachytherapy applicator insertion, HA was injected into the rectovaginal space transperineally or transvaginally under transrectal ultrasound (TRUS) guidance by a radiation oncologist. Following applicator insertion, MRI was performed for planning and standard treatment Keywords: vaginal tumours, interstitial needle, MRI 822