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A modular phantom and software to characterize 3D geometric distortion in MRI
- Source :
- Phys Med Biol
- Publication Year :
- 2020
-
Abstract
- 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 T2 weighted pulse sequences with 2D and 3D distortion correction algorithms and the receiver bandwidth (BW) varied as 250-815 Hz/pixel. Phantom set-up reproducibility was evaluated across independent set-ups. The software was validated by comparison with a non-modular phantom. Average geometric distortion was 0.94+/-0.58 mm for the MR-Linac, 0.90+/-0.53 mm for the 1.5 T scanner, and 1.15+/-0.62 mm for the 3.0T scanner, for a 400 mm diameter volume-of-interest. GD increased, as expected, with decreasing BW, and with the 2D versus 3D correction algorithm. Differences in GD attributed to phantom set-up were 0.13 mm or less. Differences in GD for the two software applications were less than 0.07 mm.<br />25 pages
- Subjects :
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FOS: Physical sciences
Imaging phantom
Linear particle accelerator
Article
030218 nuclear medicine & medical imaging
03 medical and health sciences
0302 clinical medicine
Software
medicine
Humans
Radiology, Nuclear Medicine and imaging
Physics
Reproducibility
Radiological and Ultrasound Technology
medicine.diagnostic_test
business.industry
Phantoms, Imaging
Reproducibility of Results
Magnetic resonance imaging
Physics - Medical Physics
Magnetic Resonance Imaging
Mockup
030220 oncology & carcinogenesis
Medical Physics (physics.med-ph)
Particle Accelerators
Fiducial marker
business
Algorithms
Biomedical engineering
Subjects
Details
- ISSN :
- 13616560
- Volume :
- 65
- Issue :
- 19
- Database :
- OpenAIRE
- Journal :
- Physics in medicine and biology
- Accession number :
- edsair.doi.dedup.....efef43893a58964e00f64160670a4218