ESTRO 2025 - Abstract Book

S3014

Physics - Image acquisition and processing

ESTRO 2025

References: [1] Iyengar, Puneeth, et al. (2023) "Treatment of oligometastatic non-small cell lung cancer: an ASTRO/ESTRO clinical practice guideline." Practical radiation oncology [2] Thengumpallil, Sheeba, et al. (2016) "Difference in performance between 3D and 4D CBCT for lung imaging: a dose and image quality analysis." Journal of applied clinical medical physics [3] O'Brien, Ricky T., et al. (2021) "The first-in-human implementation of adaptive 4D cone beam CT for lung cancer radiotherapy: 4DCBCT in less time with less dose." Radiotherapy and Oncology [4] Sweeney, Reinhart A., et al. (2012) "Accuracy and inter-observer variability of 3D versus 4D cone-beam CT based image-guidance in SBRT for lung tumors." Radiation Oncology

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Digital Poster Efficient DTI Protocol for Stereotactic Radiotherapy Planning: Balancing Acquisition Time and Axonal Fidelity Christian MATHIS 1 , Paul RETIF 2,3 , Marie-Hélène BARON 4,5 , Xavier MICHEL 4 , Rémi DUPRES 1 1 Medical Imaging Department, CHR Metz-Thionville, Metz, France. 2 Medical Physics Unit, CHR Metz-Thionville, Metz, France. 3 CRAN, CNRS, Université de Lorraine, Nancy, France. 4 Radiotherapy-Brachytherapy Department, CHR Metz Thionville, Metz, France. 5 Neuro-Oncology Department, CHRU-Nancy, Nancy, France Purpose/Objective: The study aimed to optimize a Diffusion Tensor Imaging (DTI) sequence for use in stereotactic radiotherapy (SRT) planning, balancing acquisition time with the accuracy of critical axonal bundle mapping to minimize neurological risks in brain metastases treatment [1-4]. Material/Methods: We developed a shortened (duration: 2.1 minutes) DTI sequence on a Siemens SOLA 1.5T MRI, adjusting spatial resolution to 3 mm (reconstructed to 1.5 mm, isotropic) and reducing directions to 20 without repetition. The sequence was evaluated, on a healthy volunteer, for accuracy in mapping key axonal structures—left/right corticospinal tracts, optic radiations, and the left arcuate fasciculus—using Brainlab’s FiberTracking V2.0 software and compared to standard (20 directions with repetition, 4.1 minutes) and reference (256 directions, 26.5 minutes) sequences. Comparability has been assessed visually and using the DICE metric. Results: The optimized sequence maintained visually comparable performance with standard and reference DTI protocols in identifying target axonal bundles essential for radiotherapy planning. When applying a margin of 2 mm on the reference bundles, we found a ~95% overlap between the structures. The reduction in acquisition time did not compromise the visualization of critical axonal pathways, making the sequence suitable for clinical workflow without loss of anatomical fidelity.