Aliasing artifact (CT)

Andrew Murphy ◉ et al.

Aliasing artifact, otherwise known as undersampling, in CT refers to an error in the accuracy proponent of analog to digital converter (ADC) during image digitisation.

Image digitisation has three distinct steps: scanning, sampling, and quantization.

When sampling, the brightness of each pixel in the image is measured, and via a photomultiplier, creates an output analog signal that is then due to undergo quantization.

The more samples that are taken the more accurate the representation of the signal will be, hence if a lack of sampling has occurred the computer will process an inaccurate image resulting in an aliasing artifact.

The artifact has the appearance of Moiré patterns.

Quiz questions

References

Physics and imaging technology: CT

computed tomography (CT)
- CT technology
- dual energy CT
  - clinical applications of dual energy CT
    - virtual non-contrast imaging
    - abdominal
    - vascular
    - urinary system
    - musculoskeletal
- CT image reconstruction
- CT image quality
- CT dose
- CT contrast medium
  - iodinated contrast media
- coronary CT angiography
- CT artifacts
  - patient-based artifacts
    - motion artifact
    - transient interruption of contrast
  - physics-based artifacts
  - hardware-based artifacts
    - ring artifact
    - tube arcing
    - out of field artifact
    - air bubble artifact
    - helical and multichannel artifacts
- CT safety
- history of CT
  - Godfrey N Hounsfield

Article information

rID: 52109

Section: Radiography, Physics

Tag: cases, snippet title

Synonyms or Alternate Spellings:

Aliasing artefact (CT)

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