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Flashcards in Artifacts Deck (8)
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1

Beam hardening

Cause: attenuation
Appearance: shading or streaks
How to fix/avoid:
-select appropriate SFOV
-beam hardening reducing software

2

Partial volume

Cause: more than 1 type of tissue in a voxel
Appearance: shading
How to avoid/fix:
-thinner slices
-smaller pixels

3

Motion

Cause: the patient, voluntary and involuntary
Appearance: shading, streaking or blurring
How to avoid/fix:
-software correction
-cardiac gating
-communication
-immobilization
-sedation
-short scan times

4

Metallic

Cause: density of metal exceeds HU value range of the system
Appearance: streaks
How to avoid/fix:
-metal reducing software
-removal of external metallic objects
-⬆️ kVp
-thinner slices

5

Out-of-field

Cause: anatomy that is outside the SFOV
Appearance: streaks and shading
How to fix/avoid:
-move anatomy out of the way
-⬆️ SFOV

6

Cone beam

Cause: helical and MDCT scans, data interpolation, cone beam geometry
Appearance: streaks or shading
How to avoid/fix: ⬇️ pitch, use cone beam reconstruction algorithms

7

Rings and bands

Cause: malfunctioning or miscalibrated detector elements
Appearance: rings or bands
How to avoid/fix: recalibration, service engineer

8

Noise

Cause: quantum noise, inherent physical limitations, reconstruction parameters
Appearance: salt and pepper
How to avoid/fix:
-⬆️ mAs
-use a low-noise DAS system
-smoothing reconstruction algorithms