Aliasing artefact (CT)

Mr Andrew Murphy et al.

Aliasing artefact, otherwise known as undersampling, in CT refers to an error in the accuracy proponent of analogue 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 analogue 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 artefact. 

The artefact has the appearance of Moiré patterns.


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rID: 52109
Sections: Radiography, Physics
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