A phantom based laser marking workflow to visually assess geometric image distortion in magnetic resonance guided radiotherapy. (January 2021)

• Record Type: Journal Article
• Authors: Drobnitzky, Matthias; vom Endt, Axel; Dewdney, Andrew
• Is Part Of: Physics and imaging in radiation oncology. Volume 17(2021)
• Page Start: 95
• Page End: 99
• Publication Date: 2021-01
• Subjects: Gradient nonlinearity -- MR distortion correction -- Lightweight plastic skeleton -- Silicone-based spherical fiducials -- External laser bridge -- Patient marking workflow; Radiotherapy -- Periodicals; Radiation dosimetry -- Periodicals; Cancer -- Imaging -- Periodicals; Oncology -- Periodicals; 615.842
• DOI: 10.1016/j.phro.2021.01.012
• Languages: English
• ISSNs: 2405-6316

Abstract

Abstract: Magnetic resonance (MR)-only workflows require quality assurance due to potential dosimetric impacts of using geometry distorted MR images in radiotherapy planning. MR-visible silicone-based fiducials were arranged in regular 3D structures to cover extended imaging volumes. The scanner's patient marking workflow with a 2-axes movable laser bridge allowed to visually check geometric distortions of each MR reconstructed fiducial against its true position in 3D space. A measurement resolution and uncertainty of the order of 0.5 mm in sagittal and coronal, and 1 mm in transversal direction was found. The proposed workflow required 1 min of evaluation time per fiducial position, and a 9 min 3D MR volume acquisition.