ESTRO 2025 - Abstract Book

S3279

Physics - Intra-fraction motion management and real-time adaptive radiotherapy

ESTRO 2025

Conclusion: A motion robust PET and MR-linac pipeline employing motion corrected PET imaging and MR-guided MLC tracking is technically feasible and enhances dose conformity. Only correcting for motion either during PET imaging or during treatment delivery may still lead to suboptimal deposited dose distributions.

Keywords: PET-guided radiotherapy,MR-Linac, Motion-corection

References: [1] José Santo R, Waterink E, van den Berg CAT, de Jong HWAM, Sbrizzi A, Beijst C, PET-MOTUS: 500 ms non rigid motion estimation and correction for PET imaging, IEEE NSS MIC Conference Proceedings (2024) [2] Uijtewaal P, Borman PTS, Woodhead PL, Hackett SL, Raaymakers BW, Fast MF. Dosimetric evaluation of MRI guided multi-leaf collimator tracking and trailing for lung stereotactic body radiation therapy. Med Phys 2021;48:1520–32. https://doi.org/10.1002/MP.14772.

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Digital Poster Reduce, Reuse, Recycle: An underutilised strategy in adaptive radiotherapy Sarah A Mason 1,2 , Bethany Williams 1 , Sophie E Alexander 1,2 , Alex Dunlop 1,2 , Alison Tree 1,2 , Emma J Harris 1,2 , Helen McNair 1,2 1 Radiotherapy, Royal Marsden NHS Foundation Trust, Sutton, United Kingdom. 2 Radiotherapy and Imaging, Institute of Cancer Research, London, United Kingdom Purpose/Objective: Although there is significant dosimetric benefit afforded by online adaptive radiotherapy (oART) 1 , very few patients receive this treatment as generating a new plan at every fraction is presently slow and resource intensive. One method to address this involves reusing plans generated online in fractions with similar patient anatomy 2,3 . However, manually assessing the suitability of each pre-existing plan is subjective and time-consuming.