QC/PACS Artifact Identification

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QC/PACS ArtifactIdentification
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Artifact Causes

• Image receptor/Hardware
• Dirty
• Foreign material
• Failures
• Software
• Algorithm
• Enhancements/manipulations
• Operator/Patient
• Collimation
• Misused equipment
• Incorrect patient data entry

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Image Receptor/Hardware

• Dirt
• In the CR cassette or reader
• Foreign material
• Matter other than dirt within the CR cassette or
  reader
• Failures
• Dead pixels
• Mechanical failures with in the CR reader
• Within the PACS network

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CR Screen Artifacts
These are caused by Dirt or other foreign matter
within the cassette/plate apparatus
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Dead Pixels

• Calibration algorithms detect individual pixels,
  clusters, and lines of contiguous pixels that
  fail to produce a usable output value.
  Algorithms are applied to the image to determine
  pixel values for the dead or missing pixels.

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CR Ghost Images
Ghost or memory artifacts occur when the
radiation remains trapped in the phosphor plate.
Remember, radiation can remain trapped for
several minutes. CR plates must be correctly
erased to prevent ghost images.
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Ghost Image

• This artifact can also occur with DR systems
  particularly systems using photodiodes.
• The artifact occurs when exposures are made too
  rapidly and the unit was unable to clear its data
  completely.

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CR Reader Artifacts

• Typically display as lines across the entire
  image
• In contrast to dirt within the cassette or on the
  PSP which are shorter and/or curved lines.

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Damaged laser beam head
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Transmission errors in the network
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Printer Distortion

• Occurs when the image size and the printed size
  are not equal.

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Software Causes

• Algorithms
• Incorrect selection
• Age related
• Pathology induced
• Post-processing
• Edge enhancement, etc

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Edge Enhancement

• High contrast and edge definition
• Lose fine detail on the edges of high contrast
  areas

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For the pediatric chest an adult chest algorithm
was selected. Technologist error.
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DR - RF Noise
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Operator Errors

• Collimation
• Backscatter
• Moire artifact
• Quantum mottle
• Insufficient mAs

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Collimation

• Too much or too little collimation may effect
  image quality. When being reconstructed the
  image histogram has been programmed to search for
  a particular collimation pattern. If the
  collimation is faulty it may result in artifacts
  on the final image.

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Light bulb Artifact
Image A demonstrates backscatter on the image
which produces a light bulb effect within the
image. Image B shows the same image with less
kVp.
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Moire Pattern
Grid lines run in the same direction as the laser
in the CR reader.
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Quantum Mottle
Image A demonstrates quantum mottle resulting
from too few photons striking the imaging plate.
Images B and C show increasing mAs values and
decreasing quantum mottle.
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Conclusion

• Digital artifacts can be caused by numerous
  means.
• It is the responsibility of the II/PACS
  professional to be the final monitor of image
  quality within the modern imaging department.

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Future Possibilities
Digital image monitoring