Keywords:
Performed at one institution, Experimental, Not applicable, Image verification, Artifacts, Technical aspects, Radiation therapy / Oncology, Experimental investigations, MR, Oncology, MR physics, MRI
Authors:
Y. kato, K. okudaira, M. kumagai, T. Taoka, T. Kamomae, Y. Itoh, S. Naganawa; Nagoya/JP
DOI:
10.26044/ecr2020/C-01229
Purpose
Magnetic resonance imaging (MRI) has been increasingly used for radiation treatment planning (RTP) because of its superior soft tissue contrast compared with computed tomography [1, 2]. However, MR images are typically affected by system-related and object-induced distortions (Fig. 1). These distortions are further enhanced in modern scanners that use a shorter bore magnet and faster and stronger gradient systems. On the other hand, a geometrically accurate representation of the tumor and the organs at risk is essential for RTP [3]. Therefore, unavoidable distortions inherent to MRI may affect the anatomical coordinate system, thus undermining the implemented RTP quality. Several studies have already provided a detailed characterization of the geometric distortion and performance of vendor specific 2D and 3D geometric distortion correction (DC) over a large field of view (FOV). However, it is generally difficult to evaluate large FOV distortions because there is no suitable phantom. In this study, our aim was to quantitatively evaluate MRI geometric distortions over a large FOV using an existing small phantom and to show the effectiveness of 3D-DC.