Development of a phantom for dose distribution verification in Stereotactic Radiosurgery

Barbosa, Nilseia Aparecida; Rosa, L.A.R. da; Batista, Delano V. S.; Carvalho, Arnaldo Rangel

doi:10.1016/j.ejmp.2013.01.002

Cited by 6 publications

(1 citation statement)

References 15 publications

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“…The success of SRS is crucially dependent on the individual accuracy of target visualization and localization within stereotactic space, as characterized by the combined imaging modalities used for SRS, and the dosimetric accuracy of dose calculation and delivery (Mack and Mack et al 2004, Mack et al 2005, Barbosa et al 2013.…”

Section: Discussionmentioning

confidence: 99%

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: Discussionmentioning

confidence: 99%