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Physics 3 > Chapter 21 Pt 1 > Flashcards

Chapter 21 Pt 1 Flashcards

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0
Q

Artifacts are reflections that are described as what 5 things?

A 
Not real
Not seen on the image 
Incorrect shape or size 
Incorrect position 
Incorrect brightness
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1
Q

An ______ is essentially an error in imaging

A

Artifact

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2
Q

What 4 things do artifacts result from?

A
  • Violation of assumptions
  • Equipment malfunction or poor design
  • the physics of ultrasound
  • operator error
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3
Q

Portions of an image that are brighter than surrounding tissues, or tissues that appear brighter than normal

A

Hyperechoic

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4
Q

Portions of an image that are not as bright as surrounding tissues, or tissues that appear less bright than normal

A

Hypoechoic

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5
Q

An extreme form go hypoechoic, meaning entirely without echoes

A

Anechoic

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6
Q

Describes structures with equal echo brightness

A

Isoechoic

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7
Q

A portion of the tissue or an image that has similar echo characteristics throughout

A

Homogeneous

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8
Q

A portion of the tissue or an image that has differing echo characteristics throughout

A

Heterogeneous

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9
Q

The six assumptions of imaging systems

A
  • sound travels in a straight line
  • sound travels directly to a reflector and back
  • sound travels in soft tissue at exactly 1,540m/s
  • reflections arise only from structures positioned in the beams main axis
  • the imaging plane is very thin
  • the strength of a reflection is related to the characteristics of the tissue creating the reflection
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10
Q

_____ malfunction should be considered when obvious artifacts remain visible even after corrective measures have been takes

A

Instrument

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11
Q

______ appears on the display as multiple, equally spaced echoes caused by the bouncing of the sound wave between two strong reflectors positioned parallel to the ultrasound beam

A

Reverberations

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12
Q
  • appear in multiples
  • appear equally spaced
  • are located parallel to the sound beams main axis
  • are located at ever-increasing depths
A

Reverberation characteristics, reverberations resemble a ladder or Venetian blind

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13
Q

The first or second reflections (in reverberation), ______ to the transducer are real, but the remainder are not

A

Closest

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14
Q

Comet tail artifact often described as “reverberation with the spaces squeezed out” appears as a ______ line directed downward! it is also known as ring down artifact

A

Solid hyperechoic

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15
Q

______ artifacts is created when closely spaced reverberations merge. It is more likely to appear when reflecting surfaces are located in a medium with a very high propagation speed, such as a mechanical heart valve

A

Comet tail

16
Q

Comet tail can also arise from the resonance, or vibration, of small structures such as gas bubbles after they have been bombarded by a ______

A

Sound Pulse

17
Q

______ appears as a hypoechoic or anechoic region extending downward from a highly attenuating structure, they are the same color as the image background

A

Shadowing

18
Q

Shadows appear when the attenuation is ______ in the tissue above the shadow than in the surrounding tissue

A

Higher

19
Q
  • hypo-or anechoic
  • the result of too much attenuation
  • located beneath the structure with abnormally high attenuation
  • prevents visualization of true anatomy on the scan
A

Characteristics of shadowing, it is unrelated to speed of sound in a medium

20
Q

An ______ artifact is a special from of shadowing that appears as a hypoechoic region extending down from the edge of a curved reflector; it prevents the display of true anatomic structure that are positioned within the extended hypoechoic region

A

Edge shadowing

21
Q

With edge shadowing the sound beam ______ (transmits with a bend) at the edge of a curved reflector, the beam simultaneously diverges, resulting in a drop in intensity

A

Refracts

22
Q

What’s is another name for edge shadowing?

A

Shadowing by refraction

23
Q
  • hypo or anechoic
  • results when the beam spreads after striking a curved reflector
  • extends downward from the curved reflectors edge, parallel to the beam
  • prevents visualization of true anatomy on the scan
A

Characteristics of edge shadowing

24
Q

_____ artifact appears as a hyperechoic region beneath tissues with abnormally low attenuation

A

Enhancement

- it is unrelated to the speed at which sound travels in a medium

25
Q
  • hyperechoic
  • the result of too little attenuation
  • located beneath a structure with abnormal low attenuation
A

Characteristics of enhancement

26
Q

______ is a special form of enhancement in which a side-to-side region of an image appears brighter than tissues at other depths

A

Focal enhancement

27
Q

What is an other name for focal enhancement?

A

Focal bending- resembles incorrect TGC settings

28
Q

Structures at the ______ appear brighter than those at other depths in focal enhancement

A

Focus

29
Q
  • a hyperechoic side-to-side region

- results from increased intensity at the focus

A

Characteristics of focal enhancement

30
Q

______ artifact is created when sound reflects off a strong reflector, and is redirected toward a second structure. The redirection causes a replica of the structure to incorrectly appear on the image

A

Mirror artifact

31
Q

The mirror artifact is located ______ than the real structure, the mirror is always located along a straight line between the transducer and the artifact

A

Deeper

32
Q

-a second copy of a true reflector
-the artifact appears deeper than the true reflector a bright reflector, the mirror, lies on a straight line between the artifact and the transducer
-true reflector and artifact are equal distance from the mirror
-

A

Characteristics of a mirror image artifact

33
Q

______ article is a mirror image artifact that appears on a spectral Doppler display

A

Crosstalk

34
Q

______ artifact is created when a sound wave propagates through a medium at a speed other than that of soft tissue. The correct number of reflectors are displayed but they appear an incorrect depths

A

Speed error

35
Q

In speed error what happens when the mediums speed is slower than that in soft tissues?

A
  • sounds travels slower than US system expects
  • go-return time is too long
  • system assumes reflectors are far from transducer
  • reflectors placed too deep on image
  • distances are overestimated
36
Q

In speed error what happens when the mediums speed is faster than that in soft tissues?

A
  • sounds travels faster than US system expects
  • go-return time is too short
  • system assumes reflectors are close to the transducer
  • reflectors are located too shallow on image
  • distances are underestimated
37
Q

Propagation speed errors are also called ______

A

Range error artifact

38
Q
  • Correct number of reflectors
  • improper depth
  • appears as a step-off
A

Characteristics of speed error

Physics 3 (7 decks)

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