ESTRO 2025 - Abstract Book

S224

Brachytherapy - Gynaecology

ESTRO 2025

in making well-informed decisions regarding the selection of a specific applicator for a given ICB session on a particular patient. We compare the reference volume encompassed within the 100% isodose line of the prescribed dose (V ref ), the 60Gy volume (V 60Gy ), rectum and bladder point doses, point B doses according to the International Commission on Radiation Units & Measurements-38 (ICRU-38) recommendations and total reference air-kerma (TRAK) values, when both applicators are utilized alternatively during consecutive ICB sessions on each patient. Material/Methods: Between September 2022 to December 2023, 24 patients with locally advanced cervical cancer (LACC) ranging from stage IB3 to IVA according to International Federation of Gynecology and Obstetrics-2018 (FIGO-2018), received HDR ICB in 3-4 sessions of 7Gy following completion of external beam radiotherapy (EBRT) in a dose of 45-50.4Gy with weekly cisplatin. It was ensured that the largest size TO or TR applicator, that a particular patient's anatomy could accommodate, utilized during each ICB insertion. During one ICB insertion utilizing TO applicators vaginal packing (VP) was used and during two insertions utilizing TR applicators both rectal retractor blade (RR) or combination of RR and customized VP were alternated for rectum separation. Fourth insertion, if applicable, was performed utilizing combination of that applicator type and rectum separation method which yielded best dosimetric parameters in previous insertions on that particular patient. A stringent treatment planning criteria of adhering to a standard loading pattern without optimization for prescribing optimum dose to point A taken according to American Brachytherapy Society (ABS) definition (r+2cm), during each ICB insertion was followed in this cohort of patients [1]. The organs-at-risk doses were kept below defined limits. (Fig. 1)