Aliasing artifact (CT)

Last revised by Andrew Murphy on 23 Mar 2023

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

Image digitization 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.

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