S2994
Invited Speaker
ESTRO 2026
with CT for dose calculation due to MRI’s inherent geometric distortions. Weekly MRI verification imaging supports treatment adaptation without additional radiation dose and rescans are extremely important for significant patient changes leading to replans. A critical component of successful MRI integration is the embedding of robust safety and training frameworks. MRI safety must be fully incorporated into workflows, supported by local rules, screening pathways, and clear staff responsibilities. The role of the MR Safety Officer (MRSO) is essential in maintaining safe practice. Equally important is workforce development: a multidisciplinary approach involving radiographers, oncologists, radiologists, and physicists is required. Ongoing staff training, competency frameworks, and cross-specialty education are vital to ensure safe, efficient, and high- quality patient care. Advances in MRI hardware, software, and artificial intelligence are expected to further transform radiotherapy practice. MRI-only planning, MRI-guided linear accelerators, and quantitative imaging techniques offer opportunities for personalised and adaptive treatment. AI-driven tools are already improving contouring efficiency, consistency, and predictive modelling of treatment response and toxicity. In conclusion, the integration of MRI within multi- modality imaging frameworks is enhancing precision, adaptability, and personalisation in Radiotherapy. Supported by a strong safety culture and workforce training, MRI will play a significant role in shaping the future of both proton and photon based treatment. 5298 Simulator-free adaptive radiotherapy: Explore real- world implementation of sim-free workflows using CBCT or MRI for on-the-day adaptation Melissa O'Neil Radiation Oncology, London Health Sciences Centre, London, Canada Background Simulation-free radiotherapy (SFRT) is redefining palliative radiotherapy delivery by improving timeliness, access, and patient-centred care. By omitting conventional CT simulation (CT sim) and leveraging existing diagnostic imaging with image- guided radiotherapy (IGRT) and/or on-table adaptation, SFRT fundamentally challenges traditional workflows. An expanding evidence base and growing clinical experience have established SFRT as a feasible and increasingly adopted approach in selected clinical scenarios. Content This teaching session synthesizes the clinical rationale,
system and how their interaction is reflected in tumor control with an emphasis on innovative, emerging SFRT techniques. Highly complex clinical situations of patients with very voluminous, hypoxic and radioresistant bulky unresectable tumors that conventional radiotherapy can hardly cope with will be presented. It is precisely on such tumors that SFRT techniques are currently applied, showing an enviable immunomodulatory and neoadjuvant potential that could potentially improve the radiotherapy therapeutic ratio, hopefully changing the prognosis of patients. The topic is relevant for all disciplines, especially for the preclinical and clinical investigational research in the field of radio-oncology and immunology. 5297 Multimodality imaging integration: Practical insights and future innovation for MRI planning in radiation therapy Anna J Crawley Proton Beam Therapy, University College London Hospitals NHS Foundation Trust, London, United Kingdom Multi-modality imaging is central to modern Radiotherapy, enabling precise tumour targeting while minimising healthy tissue toxicity and adapting to anatomical and physiological changes throughout treatment. This presentation explores the integration of imaging modalities within Radiotherapy, with a particular focus on the expanding role of magnetic resonance imaging (MRI) and shares practical clinical insights from its application in Proton Beam Therapy (PBT). Lastly time is spent considering future innovations for MRI in Radiotherapy. Radiotherapy planning relies on the complementary strengths of different imaging techniques. Computed Tomography (CT), including emerging spectral CT, remains essential for electron density mapping and dose calculation. Positron emission tomography (PET- CT) provides functional and metabolic information, supporting tumour characterisation and detection of nodal or metastatic disease. MRI, offers superior soft tissue contrast without ionising radiation, enabling improved tumour and organ-at-risk delineation. Its multiplanar capability and high-resolution imaging reduce inter-observer variability and can support
more confident clinical decision making. Within PBT, where dose distribution differs
significantly from photon therapy, accurate imaging is critical. MRI plays an increasingly significant role in refining target volumes and supporting adaptive strategies. Practical implementation requires careful workflow design, including Radiotherapy specific protocols, reproducible positioning, and integration
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