ESTRO 2025 - Abstract Book

S2976

Physics - Image acquisition and processing

ESTRO 2025

1474

Digital Poster Sub-Second Temporal Resolution 4D Imaging for Target Motion Analysis: A Comparison of 4D-MRI and 4D-CT Using a Liver Tumor Phantom Model Tianyuan Wang 1,2 , Keitaro Sofue 3 , Ryuji Shimada 4 , Takeaki Ishihara 2 , Ryohei Sasaki 2 , Takamichi Murakami 3 1 Departments of Radiation Physics, Kobe Proton Center, kobe, Japan. 2 Department of Radiation Oncology, Kobe University Hospital, kobe, Japan. 3 Department of Radiology, Kobe University Hospital, kobe, Japan. 4 Center for Radiology and Radiation Oncology, Kobe University Hospital, kobe, Japan Purpose/Objective: This study has two primary objectives: first, to utilize the proposed 4D-MRI method to attain sub-second temporal resolution alongside high spatial resolution and image contrast; second, to validate its accuracy by examining respiratory-induced motion and comparing the results with 4DCT.

Material/Methods:

A gradient-echo T1-weighted 4D-MRI with sub-second temporal resolution was successfully developed through the use of advanced volumetric acquisition techniques combined with compressed sensing (CS) methodologies. To comprehensively evaluate the geometric precision associated with target motion, a specially designed motion phantom compatible with both MRI and CT systems was utilized. This phantom was engineered to simulate the behavior of a liver tumor under various respiratory patterns, allowing for a robust comparison between 4D-MRI and 4D-CT modalities. Several critical metrics, including geometric accuracy, volumetric consistency, Dice Similarity Coefficient (DSC), Hausdorff Distance (HD), and the centroid position, were rigorously and systematically analyzed as part of this evaluation.