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Physics > Chapter 21 Artifacts > Flashcards

Chapter 21 Artifacts Flashcards

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1
Q

What are the 6 assumptions in ultrasound

A

1.Sound travels in a straight line
2. Sound travels directly to a reflector and back
3. Sound travels in soft tissue exactly at 1540 m/s
4. Reflections arise only from structures positioned in the beams main axis
5. The imaging plane is very thin
6. The strength of a reflection is related to the characteristics of the tissue creating reflection

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2
Q

A violation of those ultrasound assumptions result in ______

A

Artifacts

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3
Q

What is reverberation artifact

A

Multiple equally spaced echoes cause by the bouncing of sound wave between 2 strong reflectors positioned parallel to the beam

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4
Q

What assumption does reverberation break

A

Sounds travels directly to a reflector and back

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5
Q

Comet tail artifact is also known as

A

Ring down

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6
Q

What does the comet tail artifact look like

A

Solid hyperechoic line directed downward

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7
Q

What assumption does the comet tail artifact break

A

Sound travels directly to a reflector and back

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8
Q

What is shadowing artifact

A

It happens beneath a structure with very high attenuation, hypoechoic or anechoic line extending downward

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9
Q

What assumption does shadow artifact breaks

A

The intensity of a reflection is related to the tissue creating reflection

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10
Q

Edge shadow is also known as

A

Shadowing by refraction

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11
Q

Describe edge shadowing

A

Hypoechoic region extending down from the edge of a curved reflector like a cyst

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12
Q

Edge shadowing breaks what assumption

A

The intensity of a reflection is related to the tissue creating the reflection

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13
Q

Describe enhancement artifact

A

Hyperechoic region beneath tissues with low attenuation

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14
Q

Enhancement breaks what assumption

A
  1. The intensity of a reflection is related to the tissue creating the reflection
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15
Q

Focal enhancement is also known as

A

Focal banding

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16
Q

What is focal enhancement

A

Side to side region of an image appears brighter than tissues at other depths. Happens often at the focus

17
Q

What assumption does focal enhancement break

A
  1. The intensity of the reflection is related to the tissue creating the reflection
18
Q

Define mirror image artifact

A

A string reflector creates a second structure (fake) that is always located deeper than the real structure. Both the real and the fake are at the same distance from the mirror

19
Q

Mirror image on spectral Doppler is called

A

Crosstalk artifact

20
Q

Mirror image breaks what assumptions

A
  1. Sound travels in a straight line
  2. Sound travels directly to a reflector and back
21
Q

Speed error is also known as

A

Range ambiguity artifact or range error artifact

22
Q

What is speed error

A

When a sound propagates through 2 different media, correct order of reflectors are displayed but at incorrect depths

23
Q

What assumption does speed error break

A
  1. Sound travels exactly at 1540 m/s
24
Q

Describe lobe artifacts

A

Creates a copy of reflector and are located side by side

25
Q

What assumption does lobe artifacts break

A
  1. Reflections arise from structures located along the beams main axis
26
Q

What resolution does the love artifacts degrade

A

Lateral

27
Q

What are the two types of lobe artifacts

A

Side lobes, and grating lobes

28
Q

Grating lobes are created by which kind of transducer

A

Array probes

29
Q

Side lobes are created by which kind of transducer

A

Mechanical probes

30
Q

What is refraction artifact

A

Transmission with a bend, creates second copy of reflector and it’s located side by side, think of the aorta

31
Q

Refraction breaks what assumption

A
  1. Sound travels in a straight line
32
Q

Slice thickness arrifact is also known as

A

Section thickness artifact, or partial volume artifact

33
Q

Slice thickness artifact breaks what assumption

A
  1. The image plane is extremely thin
34
Q

Elevational resolution is determined by

A

The thickness of the image plane

35
Q

Lateral resolution artifact is also known as

A

Point spread artifact

36
Q

Lateral resolution artifact occurs when

A

The beam is wider than the distance between 2 reflector located side by side. 2 objects appear as one

37
Q

Axial resolution artifact occurs when

A

2 objects located parallel to sound beam appears as one if they are closer together than 1/2 the spatial pulse length

38
Q

Multi path artifact breaks what assumption

A
  1. Sound travels directly to a reflector and back
39
Q

Clutter is noise associated with

A

Doppler

Physics (20 decks)

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