ESTRO 2025 - Abstract Book

S2878

Physics - Dose prediction, optimisation and applications of photon and electron planning

ESTRO 2025

Conclusion: We developed a workflow for calculating the rigid accumulated dose live on the MR-linac which has the potential to act as an online user-support tool for triggering intra-fractional plan adaptations Future extensions could include MR-based position updates and deformable anatomies.

Keywords: real-time, support-tool, prediction

References: [1] Kontaxis, C, et al. "Delivered dose quantification in prostate radiotherapy using online 3D cine imaging and treatment log files on a combined 1.5 T magnetic resonance imaging and linear accelerator system." Physics and imaging in radiation oncology 15 (2020): 23-29. [2] Muurholm CG, et al. Real-time dose-guidance in radiotherapy: Proof of principle. Radiother Oncol. 2021;164:175 182.

3586

Digital Poster Treatment planning of a whole left breast with lymph nodes and the IMN using VMAT, tomotherapy and proton therapy techniques: A multicentre study. Christophe Legrand 1 , Anne-Sophie Gautier 1 , Aurélie Dupas 1 , Delphine Rigal 2 , Jérémy Palisson 3 , Mathieu Attila 4 , Anthony Vela 5,6 , Laurine Bonnor 5 , Séverine Martineau 7 , Julie Ceccone 8 , Benoit Boutoleau 9 , Christine Métayer 10 , Philippe Le Dorze 11 , Ludovic Harzée 12 , Paul Rétif 13 , Valérie Gérôme 14 , Julien Demoucron 15 , Arnaud Salel 16 , Odile Boissonnade 17 , Fanny Jouyaux 18 , Camille Llagostera 19 , Caroline Noblet 20 , Jérôme Anfray 21 , Cathy Fontbonne 22 , Florence Vincent 23 1 Medical physics, Institut de Cancérologie de l'Ouest, Angers, France. 2 Medical physics, Centre Radiothérapie Oncologie Moyenne Garonne, Agen, France. 3 Radiotherapy, Centre de la Baie, Avranches, France. 4 Radiotherapy, Centre Saint-Jean, Saint Doulchard, France. 5 Medical physics, Centre François Baclesse, Caen, France. 6 Medical physics, CYCLHAD, Hérouville-Saint-Clair, France. 7 Radiotherapy, Centre Maurice Tubiana, Caen, France. 8 Medical physics, CHRU de Tours, Tours, France. 9 Medical physics, CHD Vendée, La Roche-sur-Yon, France. 10 Radiotherapy, Centre de Cancérologie de la Sarthe, Le Mans, France. 11 Medical physics, GH Bretagne Sud, Lorient, France. 12 Medical physics, Centre François Baclesse, Esch-sur-Alzette, Luxembourg. 13 Medical physics, CHR Metz-Thionville, Metz-Thionville, France. 14 Radiotherapy, Centre Louis Gray, Montargis, France. 15 Medical physics, CH de Niort, Niort, France. 16 Radiotherapy, CIMROD, Périgueux, France. 17 Medical physics, CHU de Poitiers, Poitiers, France. 18 Medical physics, Centre Eugène Marquis, Rennes, France. 19 Medical physics, Institut de Cancérologie de l'Ouest, Saint Herblain, France. 20 Radiotherapy, Clinique Mutualiste de l’Estuaire, Saint-Nazaire, France. 21 Radiotherapy, Centre d’Oncologie Saint-Yves, Vannes, France. 22 LPC, ENSICAEN, CNRS/IN2P3 UMR6534, Caen, France. 23 Radiotherapy, Centre d’Oncologie et Radiothérapie, Chambray-lès-Tours, France Purpose/Objective: Dosimetric treatment planning of a left breast, including the axillary and clavicular lymph nodes and the internal mammary nodes, is a complex task. Material resources for planning vary from one center to another, particularly in terms of particle accelerator models, Treatment Planning Systems (TPS) and the experience of the radiotherapy team. A multicentre study was carried out involving treatment using VMAT techniques, helical tomotherapy and proton therapy. Material/Methods: DICOM images and RT structures of a patient case were sent to each of the participating centers. They were asked to perform a dosimetry according to their clinical practices. The dose prescription was 50 Gy in 25 fractions for whole breast, axillary, infraclavicular and supraclavicular lymph nodes and the internal mammary nodes (IMN). A