S77
Brachytherapy - Gynaecology
ESTRO 2026
BRT to the vaginal cuff (27.5Gy in 5 fractions) between 2020 and 2024 were included in this study. According to GEC-ESTRO recommendations, HDR-BRT was prescribed to the upper 3–5cm of the vaginal cuff and 5mm depth. During planning, the tissue extending up to 3mm from the applicator surface was contoured as vaginal mucosa. Two separate treatment plans were retrospectively generated for each patient using the HIPO-algorithm: a standard plan and a mucosa- sparing plan (Figure-1). In the mucosa-sparing plans, the maximum dose to the vaginal mucosa was limited to 150% of the prescribed dose. Dosimetric parameters compared between the two plans included the HR-CTVD90 for target coverage, D2cc- doses for the bladder, rectum, and sigmoid colon, and D0.1cc for the vaginal mucosa. HDR-BRT treatment planning and dosimetric data were obtained using ONCENTRAV4.6.3.
Target coverage was comparable between both modalities (CTV D ₉₀ : 101.2% vs. 100.7%, p = 0.49). Organs-at-risk doses showed no significant differences. The total cost per patient was estimated at € 1,489.7 for HDR and € 1,215.8 for eBT, representing an 18.4% reduction for eBT primarily due to lower source-related and maintenance expenses. When bunker infrastructure costs were excluded, eBT remained the more cost-efficient option. Conclusion: Electronic brachytherapy provides dosimetrically equivalent and economically advantageous results compared with ¹⁹² Ir HDR for exclusive vaginal cuff treatments. Its reduced operational and infrastructure demands make it a valuable complementary modality, particularly in centers with limited resources or where HDR units are prioritized for complex interstitial cases. Keywords: eBT; cost-benefit analysis, endometrium Dosimetric Outcomes of Mucosa-Sparing Brachytherapy Using a Vaginal Cylinder and Planned with the HIPO Algorithm in Endometrial Cancer Sumerya Duru Birgi 1 , Nazli Alaoglu Balci 1 , Yunus Babayigit 1 , Pantea Bayatfard 1,2 , Tugba Atakul 1 , Ayfer Temur 1 , Serap Akyurek 1 1 Radiation Oncology, Ankara University, Ankara, Turkey. 2 Radiation Oncology, Denizli Onkomer Oncology Center, Denizli, Turkey Purpose/Objective: In endometrial cancer, a correlation exists between the dose received by the vaginal mucosa during high- dose-rate-brachytherapy (HDR-BRT) and the incidence of vaginal adverse events(AE).1 In this study, the dosimetric impact of limiting the maximum dose to the vaginal mucosa was analysed in postoperative endometrial cancer patients treated with HDR-BRT using the Hybrid Inverse Planning and Optimization (HIPO) algorithm. Material/Methods: Thirty patients with FIGO 2018 stage-IA or IB endometrial cancer who received postoperative HDR- Digital Poster 3932
Results: The median age was 64 years(range:47-82) and the 94% of the patients had endometrioid-type adenocarcinoma histology. According to FIGO-staging, 13 patients (43%) were stage-IA and 17 patients (57%) were stage-IB. Additional patient characteristics are presented in Table-1. The mean vaginal mucosal D0.1cc dose per fraction was 11.5Gy (SD:±2) in the standard plans and 10Gy (SD:±1.3) in the mucosa- sparing plans, showing a statistically significant reduction in the mucosa-sparing group (p<0.001). All HR-CTVD90 values remained above 90% of the prescribed effective dose for each patient. A statistically significant decrease in the HR-CTVD90 dose was observed between the standard and mucosa-sparing plans-with mean values of 5.7Gy (SD:±0.2) and 5.5Gy (SD:±0.3), respectively (p<0.001). Furthermore, D2cc values for the bladder, rectum, and sigmoid colon were also significantly lower in the mucosa-sparing brachytherapy plans compared to standard plans (all p<.001).
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