MRI manufacturers have made great strides in reducing MR system distortion. Maintaining acceptable levels of distortion relies on properly controlling a long chain of conditions. It is critical to have a robust system of quality control for key imaging performance characteristics in order to detect significant deviations before they affect clinical operations.

For more details please refer to the Magphan® RT (820, 1090 & 1230) Datasheet and Magphan® RT (820, 1090 & 1230) Product Guide.

Phantom Design

The Magphan® RT meets the specific QA needs for MR imagers used for MR guided surgery and radiotherapy planning and guidance where measurement of large fields of view are required for torso sizes encountered in clinical practice. 

Magphan® RT 820
The Magphan® RT 820 has a two-piece configuration (top and bottom) that measures geometric distortion and uniformity over 35 x 27 x 21cm. The phantom may be upgraded to the Magphan® RT 1230 model with the purchase of a center module (TMR008) to provide an extended FOV. 

Magphan® RT 1090 & 1090D
The Magphan® RT 1090 is our most advanced large-field-of-view phantom. The three-piece configuration measures geometric distortion and uniformity over a 35 x 35 x 21 cm volume along with tests for laser alignment, slice thickness, resolution, and Signal-to-Noise Ratio. The central section contains 24 contrast spheres that cover a range of T1, T2, and ADC values, as well as two slice-thickness ramps, and an insert for ion chamber dosimetry measurements. 

Magphan® RT 1230
The Magphan® RT 1230 can be configured for two different fields of view. The full three-piece configuration measures distortion and uniformity over 35 x 39 x 21 cm. By removing the central module, a smaller 35 x 39 x 21 cm FOV can be achieved.

The Magphan® RT’s modular design, when filled with solution, keeps all individual modules under 12 kg, enabling the phantom to be handled by a single person without special equipment. This design not only allows for easy handling of the phantom but also facilitates future system expansion with additional measurement modules.

Phantom Analysis

The system measures the following imaging parameters:

Geometric Distortion
The locations of several hundred 1cm sphere fiducials are measured across the volume of the phantom. The measured locations are compared to known locations to generate a 3D distortion map. The phantom modules are designed to fit together precisely and the analysis accounts for any residual positional offsets between components. Beyond the distortion map the system tracks several key indicators such as maximum and mean high 10% distortion along the cardinal axes. Analysis of optimized gradient rescaling factors for different objectives is included

Uniformity
Uniformity can be a useful indicator for common failure mechanisms in subsystems like the RF coil element. The uniformity is measured at several hundred uniform spherical sub volumes throughout the phantom. The mean signal, normalized standard deviation and spread are calculated.

Slice Thickness
We provide slice thickness ramps to provide objective slice thickness measurements on all three orthogonal axes. The automated routine provides higher quality slice thickness measurements versus manual measurements on actual clinical sequences.     

Resolution
The Magphan® RT system measures the point spread function (PSF) and the modulation transfer function from circular features in the phantom all three measurement planes.

Signal-to-Noise Ratio
Signal-to-noise ratio is measured at several places throughout the phantom. Longitudinal tracking of SNR can give early warning of component degradation or failure.

Laser Alignment
The phantom contains markers for alignment with positioning lasers. The analysis provides data on translation and rotation of the phantom in all three cardinal axes.


Smári Image Analysis Service

Smári image analysis service is included in the purchase price for 2 years. The service provides the following benefits:

  • Completely Automated: Simply upload the complete DICOM scan series of the phantom. The service automatically identifies the features, performs the analysis and prepares the report. Analysis results are saved in the database for longitudinal studies, process control and inter-machine comparisons.

  • No Installation or Manual Updates: The service is accessible from any web enabled device and requires no local installation. Updates to the service are automatic and require no user actions.

  • API Available: The Smári system includes an API that allows users to extend the system with custom analyses or interfaces.

  • Reporting, Trending and Data Analysis Included: Smári provides an informative report, tracks all parameters over time and provides comparative analysis tools between machines.