ESTRO 2025 - Abstract Book

S3315

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

ESTRO 2025

Conclusion: In the absence of access to dCT for (emergency) palliative radiation, CT-free oART is technically feasible and achieves treatment quality not significantly different to our FAST-METS procedure. In the future, the CTV can also be derived from an MRI scan or contoured directly during the on-couch procedure. We will implement this procedure for patients in 2024 and present our early findings at ESTRO.

Keywords: CT-free, CBCT plan optimization, palliative RT

References: [1] Nelissen, Koen J., Eva Versteijne, Suresh Senan, Barbara Rijksen, Marjan Admiraal, Jorrit Visser, Sarah Barink et al. "Same-day adaptive palliative radiotherapy without prior CT simulation: Early outcomes in the FAST-METS study." Radiotherapy and Oncology 182 (2023): 109538.

3576

Poster Discussion Influence of image registration algorithm complexity on intra-fraction dose accumulation in magnetic resonance-guided prostate radiotherapy Eva Benschop 1,2 , Lando Bosma 2 , Georgios Tsekas 2 , Cornel Zachiu 2 1 Faculty of Applied Sciences, Delft University of Technology, Delft, Netherlands. 2 Department of Radiotherapy, UMC Utrecht, Utrecht, Netherlands Purpose/Objective: Intra-fraction dose accumulation (DA) during MRI-guided radiotherapy (MRIgRT) of the prostate allows for online/real-time monitoring and adaptation of the treatment plan, by using image registration (IR). While DA for prostate MRIgRT is currently not implemented in clinical practice, more complex registration algorithms are being developed [1]. This raises the question whether the increased complexity of IR algorithms has a significant influence on relevant dosimetric parameters. This project investigates the difference in accumulated dose between five research-grade deformable IR algorithms with varying complexity (as described in [1] ) and two commercial-grade solutions: MIM and comprehensive motion management (CMM).