S2080
Physics - Image acquisition and processing
ESTRO 2026
from CT prosthesis contours (AS1) were registered to the sCT using a focused prosthesis-region registration.
Results Dose comparison between AS1 and AS2 showed mean differences in all PTV parameters within 0.1% and OAR D 2% within 0.4%. AS2 plans recalculated on CT showed corresponding mean differences within 0.8% and 1%. Mean gamma pass rates exceeded 96% for all DD and
For each patient, two treatment plans (42.7 Gy in 7 fractions) were created in Eclipse (Varian Medical Systems) using AS1 and AS2 (Fig. 2). Plans were compared using dose-volume histogram (DVH) parameters: PTV mean , PTV D98% , PTV D95% , and PTV D2%, for target coverage, and D 2% for OARs. AS2-based plans were additionally recalculated on CT after registration, and DVH parameters were re-evaluated. Gamma analyses were performed with dose-difference (DD) criteria of 1% and 2%, distance-to-agreement (DTA) of 1 mm and 2 mm, and a 10% dose threshold.
DTA criteria. Conclusion
This study demonstrated the feasibility of an MRI-only radiotherapy workflow for prostate cancer patients with hip prostheses, enabling target/OAR delineation, sCT generation and fiducial marker identification from a single MAVRIC-SL image volume. References Khodarahmi, I., Isaac, A., Fishman, E. K., Dalili, D., & Fritz, J. (2019). Metal About the Hip and Artifact Reduction Techniques: From Basic Concepts to Advanced Imaging. Seminars in musculoskeletal radiology , 23(3), e68–e81. https://doi.org/10.1055/s- 0039-1687898
Digital Poster 3810
Assessment of CT number accuracy in Single- Energy versus spectral CT imaging: a phantom study Gary Razinskas, Andrea Wittig-Sauerwein, Anne Richter Department of Radiotherapy and Radiation Oncology, University Hospital Würzburg, Würzburg, Germany
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