QUASAR™ GRID3D Image Distortion Analysis System

The QUASAR™ GRID3D Image Distortion Analysis System is designed to evaluate image distortion in 3D MR images for stereotactic radiosurgery (SRS).

The system is comprised of a phantom and analysis software which work together to produce a 3D map of spatial distortion with submillimeter accuracy throughout a volume of interest. The GRID3D System ensures that MR imaging can support the outstanding geometric precision and dosimetric accuracy of the Leksell Gamma Knife®, including PERFEXION™.

The phantom is an acrylic cube containing a 1 cm 3D grid of channels filled with copper sulfate solution.

The region of interest measures 14 x 13 x 11 cm3 in which there are 2002 vertex locations. The vertex locations are known to within 0.1 mm. The phantom accurately and reproducibly mounts securely to the Leksell® Coordinate Frame G at a known position. It fits within both the Leksell® MR Indicator and Leksell® CT Indicator.


Key Features

  • Verify geometric accuracy of different MR pulse sequences
  • Compatible with the Leksell Gamma Knife®, including PERFEXION™ (fiducial box is required)
  • Automated image analysis provides full 3D distortion map with submillimeter accuracy

DICOM images of the phantom are imported from the scanner into the software. These images can be axial or coronal MR, as well as CT and the fiducials must be visible.

The software automatically finds the fiducials and locates each vertex within the phantom in 3D. A proprietary algorithm accurately determines the x, y, z and r deviations of the location of each vertex in the image. Users can then interrogate and, if necessary, edit the results vertex by vertex, as well as plane by plane.

The results are displayed in a tabular form and in a 3D display. The software saves the analysis results and generates a report in Excel. The software runs on Windows XP, Vista and 7 operating systems.

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