P37. Design of a geometric distortion characterization method in 3D MRI: Stereotactic application

Sewonu, A.; Carbillet, F.; Rousseau, Hélène; Moreno, Ramiro

doi:10.1016/j.ejmp.2016.11.049

Cited by 1 publication

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“…Other designs, making use of arrays of holes, or small spheres mounted on planar support structures (Jovicich et al 2006, The Phantom Laboratory 2017, JRT Associates 2017, Sewonu et al 2016 generally suffered by not being able to meet requirements 6, 7 and 8. Moreover, the requirements of localization accuracy and image resolution meant that the dimensions of the grid 'lines' and vertices themselves needed to be constrained.…”

Section: D-phantom 211 Design Criteriamentioning

confidence: 99%

“…Accordingly, various 3D-distortion phantom designs have been proposed, generally consisting of parallel planar plastic grids separated by gap-planes, containing water or mineral oil (Wang et al 2004a, Wang et al 2004b, p 1211; or arrays of holes or liquid-containing spheres mounted on concentric cylinders or planar support structures, to provide vertices for the calculation of image distortion (Jovicich et al 2006, The Phantom Laboratory 2017, JRT Associates 2017, Sewonu et al 2016. Though satisfying many of the requirements for the evaluation of MR-image distortion, these designs do not provide the sub-millimeter positional accuracy, dense distribution, uniform spacing and geometrically identical array of vertices in all three orthogonal imaging planes necessary to SRS applications.…”

Section: Introductionmentioning

confidence: 99%

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Design and implementation of a 3D-MR/CT geometric image distortion phantom/analysis system for stereotactic radiosurgery

et al. 2018

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The design, construction and application of a multimodality, 3D magnetic resonance/computed tomography (MR/CT) image distortion phantom and analysis system for stereotactic radiosurgery (SRS) is presented. The phantom is characterized by (1) a 1 × 1 × 1 (cm) MRI/CT-visible 3D-Cartesian grid; (2) 2002 grid vertices that are 3D-intersections of MR-/CT-visible 'lines' in all three orthogonal planes; (3) a 3D-grid that is MR-signal positive/CT-signal negative; (4) a vertex distribution sufficiently 'dense' to characterize geometrical parameters properly, and (5) a grid/vertex resolution consistent with SRS localization accuracy. When positioned correctly, successive 3D-vertex planes along any orthogonal axis of the phantom appear as 1 × 1 (cm)-2D grids, whereas between vertex planes, images are defined by 1 × 1 (cm)-2D arrays of signal points. Image distortion is evaluated using a centroid algorithm that automatically identifies the center of each 3D-intersection and then calculates the deviations dx, dy, dz and dr for each vertex point; the results are presented as a color-coded 2D or 3D distribution of deviations. The phantom components and 3D-grid are machined to sub-millimeter accuracy, making the device uniquely suited to SRS applications; as such, we present it here in a form adapted for use with a Leksell stereotactic frame. Imaging reproducibility was assessed via repeated phantom imaging across ten back-to-back scans; 80%-90% of the differences in vertex deviations dx, dy, dz and dr between successive 3 T MRI scans were found to be ⩽0.05 mm for both axial and coronal acquisitions, and over >95% of the differences were observed to be ⩽0.05 mm for repeated CT scans, clearly demonstrating excellent reproducibility. Applications of the 3D-phantom/analysis system are presented, using a 32-month time-course assessment of image distortion/gradient stability and statistical control chart for 1.5 T and 3 T GE TwinSpeed MRI systems.

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Section: D-phantom 211 Design Criteriamentioning

confidence: 99%