ESTRO 2025 - Abstract Book

S331

Brachytherapy - Physics

ESTRO 2025

Conclusion: The results indicate that either imaging modality, CT or MR, could be used for treatment planning, as the inserted needle depth showed discrepancies within tolerances in most of the cases. The three TULIP add-ons configurations tested were validated for clinical use.

Keywords: Interstitial, cervix, MR

References: - Johannes C.A. Dimopoulos, Peter Petrow, Kari Tanderup, Primoz Petric, Daniel Berger, Christian Kirisits, Erik M. Pedersen, Erik van Limbergen, Christine Haie-Meder, Richard Pötter, Recommendations from Gynaecological (GYN) GEC-ESTRO Working Group (IV): Basic principles and parameters for MR imaging within the frame of image based adaptive cervix cancer brachytherapy - Eckert & Ziegler BEBIG GmbH. User Manual Interstitial Add/on Kit

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Digital Poster Interventional Radiotherapy (brachytherapy) for cervix cancer: study of intra-daily variability in contouring of organs at risk Chiara Dell`Anna 1 , Enrico Rosa 2,3 , Valentina Lancellotta 4 , Elisa Placidi 2 , Martina De Angeli 4 , Maria Vaccaro 5 , Bruno Fionda 4 , Maria Concetta La Milia 1 , Pierpaolo Dragonetti 4,1 , Rosa Autorino 6 , Leonardo Bannoni 4 , Gabriella Macchia 7 , Marco De Spirito 2,8 , Maria Antonietta Gambacorta 6,1 , Luca Tagliaferri 4,1 , Patrizia Cornacchione 2 1 Istituto di Radiologia, Universita` Cattolica del Sacro Cuore, Rome, Italy. 2 UOC Fisica per le Scienze della Vita, Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy. 3 Department of Theoretical and Applied Sciences, eCampus University, Novedrate, Italy. 4 UOC Degenze di Radioterapia Oncologica, Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy. 5 Medical Physics Unit, IRCCS Bambino Gesù Children’s Hospital, Rome, Italy. 6 UOC Servizio di Radioterapia Oncologica, Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy. 7 Oncologic Radiotherapy Unit, Responsible Research Hospital, Campobasso, Italy. 8 Sezione di Fisica, Universita` Cattolica del Sacro Cuore, Rome, Italy Purpose/Objective: Gynecological interventional radiotherapy (brachytherapy, IRT, BT) is an effective modality for treating pelvic tumors due to its ability to deliver high-dose radiation to small, targeted volumes. In our center, the current practice involves administering two treatment fractions on the same day, utilizing CT-based simulation and planning for each fraction. This retrospective study aims to assess the inter-fractional contouring variability of organs at risk (OARs) to explore the feasibility of reducing imaging and planning sessions. We achieved this by comparing the volumetric variables of two sets of structures derived from CT scans taken six hours apart.