ESTRO 2025 - Abstract Book

S334

Brachytherapy - Physics

ESTRO 2025

Conclusion: Findings support he feasibility of reducing additional imaging and planning sessions. This approach could enhance clinical efficiency and reduce patient discomfort. Future studies could further validate these findings and explore additional optimization of gynecological interventional radiotherapy protocols considering differences in the dose to the OARs.

Keywords: contours, gyn interventional radiotherapy, OARs

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Digital Poster Dosimetric Evaluation of 3D-Printed Shielding for Ophthalmic Organs at Risk in Nasal Vestibule Tumors Interventional Radiotherapy (Brachytherapy) Enrico Rosa 1,2 , Bruno Fionda 3 , Elisa Placidi 1 , Valentina Lancellotta 3 , Maria Vaccaro 4 , Patrizia Cornacchione 1 , Martina De Angeli 3 , Maria Concetta La Milia 5 , Pierpaolo Dragonetti 3,5 , Francesco Pastore 6 , Leonardo Bannoni 3 , Mariangela Massaccesi 6 , Maria Antonietta Gambacorta 6,5 , Luca Tagliaferri 3,5 , Marco De Spirito 1,7 1 Dipartimento di Diagnostica per Immagini e Radioterapia Oncologica, UOC Fisica per le Scienze della Vita, Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy. 2 Department of Theoretical and Applied Sciences, eCampus University, Novedrate, Italy. 3 Dipartimento di Diagnostica per Immagini e Radioterapia Oncologica, UOC Degenze per la Radioterapia Oncologica, Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy. 4 Department of Medical Physics, IRCCS Bambino Gesù Children’s Hospital, Rome, Italy. 5 Istituto di Radiologia, Catholic University of Sacred Heart, Rome, Italy. 6 Dipartimento di Diagnostica per Immagini e Radioterapia Oncologica, UOC Servizio di Radioterapia Oncologica, Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy. 7 Istituto di Fisica, Catholic University of Sacred Heart, Rome, Italy Purpose/Objective: Interventional radiotherapy (IRT, brachytherapy, BT) has emerged as the preferred treatment for early-stage nasal vestibule tumors, offering high rates of local control with minimal toxicity [1]. As more patients choose IRT as their primary treatment, there is an increasing demand for advanced strategies to further reduce radiation exposure to critical organs, specifically ophthalmic structures, in order to minimize long-term adverse effects. Material/Methods: This study investigates a novel approach to reducing radiation exposure to the eyes and lenses in patients undergoing IRT for nasal vestibule tumors. We included seven patients with clinical target volumes (CTV) ranging from 2.6 to 59.83 cc and evaluated a custom-designed eye protection device. This protective shield was constructed with a 3D-printed plastic outer coating and a variable-thickness layer of a cadmium-lead alloy, with a density of 8 g/cm³. Shielding thicknesses were adjusted across simulations to assess their dosimetric impact on ocular structures. Dose reduction for the eyes and lenses (D2cc and D0.01cc) was evaluated using the TG-186 algorithm [2] on the Oncentra brachytherapy treatment planning system (v4.6.2, Elekta). Each relevant structure, including the protective shields, was contoured and assigned the specific density of the alloy for the inner shields, while other structures were assigned HU-based densities.