ARTIFACTS Flashcards
(27 cards)
• Manifests broad streaks, cupping, vague areas of low density
• Common in petrous pyramids of skull, chest and shoulder and hips
• CAUSE: X-ray beams are composed of different energies
Beam-hardening artifact
Cause of Beam-hardening artifact
CAUSE: X-ray beams are composed of different energies
remedy of Beam-hardening artifact
Use appropriate filtration, calibration, and correction software. Increase kVp setting.
- CAUSE: Occurs when more than one type of tissue is
contained within a voxel; occurs when a dense object
lies to the edge of the FOV (off-center)
Partial Volume Effect
REMEDY Partial Volume Effect
Use thinner slices
- Manifest fine lines
- CAUSE: Too few samples
Aliasing effect
REMEDY Aliasing effect
REMEDY: If a partial scan was used, rescan
-using a complete arc.
-Increase scan time.
-Reduce pitch.
- Manifests a straight line radiating from high-
contrast areas, such as barium adjacent to air - CAUSE: Angle of x-ray beam varies between two
similar views
Edge gradient effect
REMEDY Edge gradient effect
- REMEDY: Largely unavoidable. Somewhat
reduced by
-thinner slices.
-Use low or neutral HU-value oral contrast in place of barium.
- Manifests as shading, streaking, blurring, or ghosting
- CAUSE: Voluntary or involuntary patient motion
Motion
remedy of Motion
Give clear breathing instructions
to the patient and reinforce the importance
of holding still.
-Use positioning aids or
immobilization devices.
- Consider sedation, particularly for pediatric patients.
-Use shortest scan time possible.
-For cardiac protocols, consider β-blockers
- Star artifact
- Manifests as streaks
- CAUSE: Objects present that are beyond
the dynamic range of the scanner; object
absorbs the photons
Metallic artifact
REMEDY OF METAL
- REMEDY: Whenever possible, remove
metallic objects from SFOV.
-Angle gantry.
-Increase technique, particularly kVp.
-Use thin slices.
- Manifests as a single ring or concentric
rings - CAUSE: Detector problem
Ring artifact
REMEDY OF RING
- REMEDY: Recalibrate; if rings persist, call
service
- Manifests no specific pattern; can range from a single streak to
severe mottling) - CAUSE: Electrical surge within the x-ray tube
Tube arcing
TUBER ARCING REMEDY
- REMEDY: Call service; tube replacement
- Manifests subtle inaccuracies in CT number
- CAUSE: Images are created from views that
- are not all in the same plane
- REMEDY: Lower pitch
Spiral interpolation artifact
REMEDY OF Spiral interpolation artifact
- REMEDY: Lower pitch
- Manifests lines appearing in a windmill
formation - CAUSE: Only on MDCT, from the cone-
shaped x-ray beam
Cone beam effect
REMEDY OF Cone beam effect
- REMEDY: Use pitch selections
recommended by manufacturer
- CAUSE: Anatomy that extends outside of
the selected SFOV; patients body obstructs
the detectors
Out-of-field artifact
remedy Out-of-field artifact
- REMEDY: SFOV can be selected that is
larger than the patient
- Manifests as bright and dark streaks
- CAUSE: Poor selection of exposure
technique; projections where photons
travel to thicker anatomy
Photon starvation (Noise)
