ESTRO 2025 - Abstract Book

S781

Clinical - Gynaecology

ESTRO 2025

435

Digital Poster Clinical target volume delineation variability in endometrial cancer patients - Serbian National study Marija Živković Radojević 1,2 , Darko Stojanović 2 , Aleksandar Tomašević 3,4 , Olivera Ivanov 5,6 , Miloš Ivanović 7 , Katarina Janković 2 , Miloš Grujić 2 , Slađana Aćimović Talijan 2 , Milica Radić 8,9 , Katarina Krasić 2 , Predrag Petrašinović 3,4 , Jelena Ličina 5,6 , Milana Ristić 9 , Boško Miljković 9 , Dušan Mitić 9 , Neda Milosavljević 1,2 1 Department of Clinical Oncology, University of Kragujevac, Faculty of Medical Sciences, Kragujevac, Serbia. 2 Centre for Radiation Oncology, University Clinical Centre Kragujevac, Kragujevac, Serbia. 3 Clinic for Radiation Oncology, Institute for Oncology and Radiology of Serbia, Belgrade, Serbia. 4 ., University of Belgrade, Faculty of Medicine, Belgrade, Serbia. 5 ., Faculty of Medicine, University of Novi Sad, Novi Sad, Serbia. 6 Clinic for radiotherapy, Oncology Institute of Vojvodina, Sremska Kamenica, Serbia. 7 Institute of Mathematics and Informatics, University of Kragujevac, Kragujevac, Serbia. 8 Department of Oncology, University of Niš, Faculty of Medical Sciences, Niš, Serbia. 9 Oncology Clinic, University Clinical Centre Niš, Niš, Serbia Purpose/Objective: Endometrial cancer is a heterogeneous group of malignancies and is the sixth most common disease in women. In recent years, with the introduction of the molecular and FIGO 2023 classification, a major shift has been made in the diagnostic and therapeutic approach, as well as risk assessment for disease progression, which determines the need for adjuvant radiotherapy. All this affects the need for standardization in the delineation of target volumes in the framework external beam radiotherapy, in which the application of artificial intelligence can be useful. The aim of this study was a national analysis of the delineation variability of the clinical target volume (CTV) in an endometrial cancer patient. Material/Methods: A national multicentric cross-sectional study based on the analysis of the variability of CTV delineation based on CT simulation images of a virtually patient with low grade endometrial adenocarcinoma FIGO 2023 stage IIA, who underwent hysterectomy with salpingo-oophorectomy and pelvic lymphadenectomy. Radiation oncologists who spend more than 50% of their working time treating gynecological malignancies from all four University Radiotherapy Centers in Serbia participated in the research, to whom the anonymized images were forwarded via a unique platform. Delineation of CTV of common iliac, external, internal iliac, presacral, obturator lymphatics and vaginal cuff was performed in accordance with actual recommendations. The researchers were asked to make a delineation for Volumetric Arc Modulated Therapy with daily Cone Beam CT verification. After delineation, the contours were anonymosusly and separately analyzed and collectively in treatment planning system Aria

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