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CT/MRI QUIZ > CT ARTIFACTS > Flashcards

CT ARTIFACTS Flashcards

1
Q

Anything appearing on the
image that is not present in the
object scanned

A

IMAGE ARTIFACT

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2
Q

Classification of CT artifacts

A

• Physics-based artifacts
• Patient-based artifacts
• Equipment-induced artifacts

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3
Q

Has:
• BEAM HARDENING
• PARTIAL VOLUME
EFFECT
• ALIASING
• EDGE GRADIENT

A

PHYSICS-BASED ARTIFACTS

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4
Q

A result of the attenuation of
the beam as it passes through
the patient

A

BEAM HARDENING

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5
Q

Caused by: polychromatic
nature of x-ray

A

BEAM HARDENING

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6
Q

• Appearance:
• Broad dark bands or
streaks(cupping artifact)
• Vague areas of high density
• Dark bands or streaks between
dense objects in the image
• Decrease in CT number

A

BEAM HARDENING

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7
Q

Types of PHYSICS-BASED ARTIFACTS

A

• BEAM HARDENING
• PARTIAL VOLUME
EFFECT
• ALIASING
• EDGE GRADIENT

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8
Q

Correction for BEAM HARDENING artifacts?

A

• Filtering the x-ray beam
• Calibration correction
• Beam hardening correction
software
• Increased kVp setting
• To select appropriate SFOV

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9
Q

Occurs when the data from the
entire section thickness is
averaged together
• Caused by:
• Thick slice
• Large pixel size

A

PARTIAL VOLUME EFFECT

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10
Q

Appearance: shading artifact to
appear in the image

A

PARTIAL VOLUME EFFECT

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11
Q

Corrections for PARTIAL VOLUME EFFECT

A

• Corrections:
• Thin slice
• Small pixel size

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12
Q

Occurs when there’s inadequate
number of projections available
for reconstruction

A

ALIASING ARTIFACT

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13
Q

• Caused by:
• Greater helical pitch
• Fast gantry rotation
• Decrease scan time
• Small FOV

A

ALIASING ARTIFACT

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14
Q

• Appearance: fine stripes or
streaks

A

ALIASING ARTIFACT

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15
Q

corrections for ALIASING ARTIFACT

A

• Corrections:
• Reduce helical pitch
• Slow gantry rotation
• Increase scan time
• Large FOV

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16
Q

• Results from irregularly shaped
objects that have a pronounced
difference in density from
surrounding structures

A

EDGE GRADIENT EFFECT

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17
Q

Caused by: Barium and air lie
adjacent to each other

A

EDGE GRADIENT EFFECT

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18
Q

• Appearance: streaks or
shading(both light and dark)

A

EDGE GRADIENT EFFECT

19
Q

• Corrections:
• Thin slice
• Low-HU oral contrast
• Increase scan time

A

EDGE GRADIENT EFFECT

20
Q

Types of PATIENT -BASED ARTIFACTS

A

• MOTION ARTIFACT
• METAL ARTIFACT
• OUT-OF-FIELD ARTIFACT

21
Q

• Results from patient movement
during the scan
• Caused By:
• Involuntary motion
• Voluntary motion

A

MOTION ARTIFACT

22
Q

Appearance: shading, ghosting,
streaking or blurring

A

MOTION ARTIFACT

23
Q

Corrections:
• Proper instruction
• Immobilization device
• Sedation
• Short scan time

A

MOTION ARTIFACT

24
Q

• Results from attenuation of
nearly 100% of the primary beam
• Caused By: presence of metallic
materials within the SFOV
• Star artifact

A

METAL ARTIFACT

25
Q

Appearance: streaks or star
artifact

A

METAL ARTIFACT

26
Q

Corrections:
• Angle the gantry
• Software algorithm
• Increased kVp
• Thin slice

A

METAL ARTIFACT

27
Q

Occurs because the anatomy
outside the SFOV attenuates the
beam but is ignored in image
reconstruction
• Caused by: anatomy that extends
outside of the selected SFOV

A

OUT -OF-FIELD ARTIFACT

28
Q

• Appearance: streaks or shading

A

OUT -OF-FIELD ARTIFACT

29
Q

Corrections:
• Place the arms away from the
SFOV
• Large SFOV

A

OUT -OF-FIELD ARTIFACT

30
Q

Types of EQUIPMENT -INDUCED ARTIFACTS

A

• RING ARTIFACT
• TUBE ARCING ARTIFACT
• HELICAL INTERPOLATION
ARTIFACT
• CONE BEAM ARTIFACT

31
Q

• Annular artifact
• Occurs with 3rd generation
scanners
• Caused by: imperfect detector
elements (faulty or out of
calibration)

A

RING ARTIFACT

32
Q

• Appearance: ring or concentric
rings on the rotational axis

A

RING ARTIFACT

33
Q

• Corrections:
• Detector calibration
• Repair (service engineer)

A

RING ARTIFACT

34
Q

Occurs when there is a large
difference in electrical
potential(undesirable surge of
electric current)

A

TUBE ARCING ARTIFACT

35
Q

• Caused by:
• Short circuit
• Degradation of vacuum within
the tube

A

TUBE ARCING ARTIFACT

36
Q

• Corrections:
• Remove residual gas(service
engineer)
• Install new tube

A

TUBE ARCING ARTIFACT

37
Q

Appearance: no specific pattern
• Single slight streak to multiple
streaks

A

TUBE ARCING ARTIFACT

38
Q

• Appearance: subtle inaccuracies
in CT number
• Corrections: low pitch

A

HELICAL INTERPOLATION ARTIFACT

39
Q

• Occurs when the table moved
continuously and the views
collected for reconstruction were
not all in the same plane
• Caused by: high pitch

A

HELICAL INTERPOLATION ARTIFACT

40
Q

CONE BEAM ARTIFACT are also known as?

A

• Windmill artifact

41
Q

Occurs only on multidetector CT
helical system

A

CONE BEAM ARTIFACT

42
Q

• Common Sites:
• Edge of the FOV
• Outer detector row

A

CONE BEAM ARTIFACT

43
Q

• Appearance:
• Streaks or bright and dark shading
near areas large density differences

A

CONE BEAM ARTIFACT

44
Q

Corrections:
• Do not use all available detectors
• Use pitch recommended by the
manufacturer

A

CONE BEAM ARTIFACTS

CT/MRI QUIZ (3 decks)

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