A modular phantom and software to characterize 3D geometric distortion in MRI.

A modular phantom and software to characterize 3D geometric distortion in MRI. Phys Med Biol. 2020 Jun 12;: Authors: Slagowski JM, Ding Y, Aima M, Wen Z, Fuller CD, Chung C, Debnam JM, Hwang KP, Kadbi M, Szklaruk J, Wang J Abstract Magnetic resonance imaging (MRI) offers outstanding soft tissue contrast that may reduce uncertainties in target and organ-at-risk delineation and enable online adaptive image-guided treatment. Spatial distortions resulting from non-linearities in the gradient fields and non-uniformity in the main magnetic field must be accounted for across the imaging field-of-view to prevent systematic errors during treatment delivery. This work presents a modular phantom and software application to characterize geometric distortion (GD) within the large field-of-view MRI images required for radiation therapy simulation. The modular phantom is assembled from a series of rectangular foam blocks containing high-contrast fiducial markers in a known configuration. The modular phantom design facilitates transportation of the phantom between different MR scanners and MR-guided linear accelerators and allows the phantom to be adapted to fit different sized bores or coils. The phantom was evaluated using a 1.5T MR-guided linear accelerator (MR-Linac) and 1.5T and 3.0T diagnostic scanners. Performance was assessed by varying acquisition parameters to induce image distortions in a known manner. Imaging was performed using T1 and T...
Source: Physics in Medicine and Biology - Category: Physics Authors: Tags: Phys Med Biol Source Type: research