ESTRO 2025 - Abstract Book

S3832

Physics - Radiomics, functional and biological imaging and outcome prediction

ESTRO 2025

also untangle intrinsic and hypoxia-induced radioresistance, comparing different patients and tumor sensitivity parameters (Figure 2).

Conclusion: We built a personalized computational mechanistic model of the microvascular environment to estimate the hypoxic volume fraction and its possible effect on RT treatment. This approach enables the development of digital twins in RT fields, providing a relevant mechanistic model to be informed with further patient data.

Keywords: microvasculature, hypoxia, digital twin

References: 1. L. Possenti, P. Vitullo, A. Cicchetti, P. Zunino, and T. Rancati, Comput Biol Med 173, 108334 (2024). 2. L. Possenti, A. Cicchetti, R. Rosati, D. Cerroni, M. L. Costantino, T. Rancati, and P. Zunino, Ann Biomed Eng (2021). 3. W. Tinganelli, M. Durante, R. Hirayama, M. Krämer, A. Maier, W. Kraft-Weyrather, Y. Furusawa, T. Friedrich, and E. Scifoni, Sci Rep 5, 17016 (2015). Acknowledgments This work is supported by the AIRC Investigator Grant no. IG21479 and the HORIZON- EURATOM-2023-NRT-01 Grant Agreement number: 101166699

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Digital Poster Technical and biological validation of prostate ADC measured on an MR-Linac: comparisons with a diagnostic MR scanner and with histology Damien J. McHugh 1,2 , Chris Moore 1 , Martin Swinton 2,3 , David L. Buckley 1,4 , Andrew Hudson 3 , Ananya Choudhury 2,3 , Robert Bristow 2 , Michael J. Dubec 1,2 1 Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester, United Kingdom. 2 Division of Cancer Sciences, The University of Manchester, Manchester, United Kingdom. 3 Clinical Oncology, The Christie NHS Foundation Trust, Manchester, United Kingdom. 4 Biomedical Imaging, Leeds University, Leeds, United Kingdom Purpose/Objective: Quantitative imaging biomarkers acquired on MR-Linacs require technical and biological/clinical validation before being used clinically to inform treatment planning or characterise response 1,2 . Biomarkers from diffusion-weighted (DW)-MRI are of particular interest 3 , but hardware constraints mean that MR-Linac sequence parameters generally differ from diagnostic scanners 4 , which may lead to differences in biomarkers such as the apparent diffusion coefficient (ADC). This work evaluates prostate ADC intra-scanner repeatability, inter-scanner reproducibility, and relationship to histology.

Material/Methods: MR acquisition and analysis Patients either had two repeat scans on an MR-Linac (MRL, Elekta Unity; b max =500 s/mm

2 ), two scans on a diagnostic

MR (dMR, Philips Ingenia MR-RT; b max =800 s/mm 2 ), or one scan on each, prior to prostatectomy (HYPROGEN, NCT05702619). DW-MRI sequence parameters differed between scanners, motivated by MRL hardware constraints 3 . ADC maps were calculated from b =0,500 s/mm 2 (MRL) and b =0,800 s/mm 2 (dMR), measuring median values in the dominant intraprostatic lesion (DIL) and non-lesion prostate (NL). Intra-scanner repeatability was assessed using the within-subject coefficient of variation (wCV), and inter-scanner differences were calculated. ADC simulations