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A New Development for Significantly Reducing Ring Artifacts in CT Scans

Posted on September 27, 2021

When performing Computed Tomography, a common artifact that frequently pops its ugly head is a ring artifact. A new Hardware/Software solution from NSI nearly eliminates ring artifacts completely while bringing other benefits to the acquisition process.

During a CT scan, pixels that do not respond to the variations in product related attenuation will cause consistent or intermittent tracks along scan trajectories which end up as rings in a CT reconstruction.

Another contributor to this artifact is product position. The area of a part that lands directly on the center of the rotational axis has no real perspective change during rotation. A ring artifact is also very commonly present in this area especially if the image has a lower signal to noise ratio in that area.

Single DR Image from CT Scan
​Ring Artifact within CT Slice

2 Comparison Scans were performed with and without the newly developed ring reduction technology. The scans were performed using severe ring artifact causing parameters.

Worst Case Ring Artifact Scan Conditions

  • Samples were positioned directly on the center of axis of rotation.
  • 4 fps – 2 Frames Averaged (FA) in acquisition
  • 4 fps – only 2 FA for Gain and Offset Corrections

Results of the Scan Comparison

  • Image Quality Increased
    • Reduction of artifacts that can mask indications or be misinterpreted as an indication.
    • Improve volume surface quality
  • Time Savings On Gain Correction Acquisition
    • Reduce # of Gain corrections
    • Reduce Gain Acquisition Times
  • No increase in scan time
  • Increase in Geometric Magnification without Ring Artifact by keeping the sample more to the center of the rotational axis.
  • Transparent Use: Routine automatically runs without additional operator involvement.

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