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Physics Final Flashcards > Artifacts, Quality Assurance & Bioeffects > Flashcards

Artifacts, Quality Assurance & Bioeffects Flashcards

1
Q

You are most likely to encounter the range ambiguity artifact in Doppler under which of the following conditions

A

Pulsed wave Doppler, PRF 22 kHz, 3 MHz Doppler frequency

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2
Q

From a SAFETY standpoint, which one of the following methods is the best

A

Low transmit output and high receiver gain

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3
Q

Sometimes this can be interpreted as an additional vessel which has a spectrum similar to that of the real vessel.

A

Doppler Mirror Image

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4
Q

When you increase the PRF in an attempt to solve the problem of aliasing, you can encounter

A

Range Ambiguity

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5
Q

An artifact that gives rise to a double or duplicated image is called

A

Split Image / Refraction

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6
Q

The most likely cause for a beam thickness artifact is

A

Volume Averaging

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7
Q

With this artifact, the correct number of echoes appear on the image; there is less than average attenuation of a structure; and the artifact is parallel to the sound beam

A

Enhancement

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8
Q

This artifact causes a sound beam to bounce off a reflector and be redirected. It places the artifact deeper than the true reflector

A

Mirror Image

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9
Q

This artifact places structures much closer to the surface than they should be.

A

Propagation Speed Error

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10
Q

With this artifact, there is high attenuation, absence of true anatomy on the scan, and structures that lie deeper than the original structure are not imaged

A

Shadow

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11
Q

The most common type of artifact encountered in patients with a shotgun wound is

A

Commet Tail Artifact

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12
Q

At this point, aliasing begins

A

The Nyquist Limit

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13
Q

With this color representation, low velocity red is separated from low velocity blue by a black line

A

Flow Reversal

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14
Q

With this color representation, high velocity red and high velocity blue are shown directly next to one another with no black line in between

A

Aliasing

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15
Q

If the wires in an AIUM test object do not appear in the same place as on the display, what is the issue

A

Registration Accuracy

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16
Q

A shadow artifact occurs behind a gallstone as a result of

A

Higher than usual attenuation

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17
Q

True or False: If sound is traveling faster than the machine expects, it places the structure shallower than it should be

A

True

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18
Q

A quality assurance program is:

A

Needed by all labs

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19
Q

The force exerted by a sound beam on an absorber or a reflector is called

A

Radiation Force

20
Q
  • Explain the ALARA principle.
  • What does ALARA stand for?
  • How can we observe the principle for which ALARA stands (give at least 3 examples)
A

-Power is set AS LOW AS REASONABLY ACHIEVABLE (while still getting diagnostic information).
-As Low As Reasonably Achievable.
-See below:
Minimize exposure time (but perform a complete diagnostic exam).
Use minimum output power & highest receiver gain required to produce optimal images.
Do not prolong studies without reason.
Do not perform studies without reason.

21
Q

Which of the following best describes an ideal epidemiologic bioeffects study

A

Randomized and prospective

22
Q

All of the following statements regarding in-vitro bioeffects are true EXCEPT:

A

In vitro bioeffects conclusions are clinically relevant

23
Q

Two things that can help reduce grating lobes are

A

The two things are subdicing and apodization

24
Q

True or False: A mirror image artifact can appear along side of the true anatomy

A

False. This artifact is always deep to the true anatomy.

25
Q

True or False: No known bioeffects are proven to occur at the levels used in diagnostic ultrasound

A

True

26
Q

What is the highest SPTA intensity of an unfocused ultrasound wave where there have been no observed bioeffects

A

100 mW/cm2

27
Q

If the output of an US machine is calibrated in dB and the output is increased by 20 dB, the beam intensity is increased by

A

100 times

28
Q

Which type of artifact appears most commonly with highly reflective objects

A

Shadowing

29
Q

Of the following choices, which is considered most important for the sonographer with regard to bioeffects

A

Duration of study

30
Q

Which one of the following sets of properties of a test phantom is most relevant when assessing depth calibration accuracy

A

Reflector spacing & Propagation speed

31
Q

The temperature increase depends on what factors

A
  • Applied intensity or power
  • Frequency (absorption is directly proportional to frequency)
  • Beam focusing
  • Tissue perfusion
32
Q

With this artifact, the correct number of echoes appear on the image; there is less than average attenuation of a structure; and the artifact is parallel to the sound beam

A

Enhancement

33
Q

An artifact that is produced from interaction of the incident beam with a curved surface and results in an acoustic shadow is

A

a refractive edge shadow artifact

34
Q

You are performing a QA test on an US system using a tissue equivalent phantom. You make an adjustment using a knob on the system console that changes the appearance of reflector brightness from fully bright to barely visible. You are evaluating what?

A

Sensitivity

35
Q

Which artifact has a grainy appearance and is caused by the interference effects of scattered sound

A

Speckle

36
Q

True or False: Generally, linear array transducers have excellent elevational resolution

A

False. The elements in a linear array transducers tend to be wide. This artifact can be rectified by using a one and a half dimensional array transducer, which makes thinner slices.

37
Q

Under which circumstances is cavitation most likely to occur

A

High pressure; low frequency

38
Q

The propagation speed of US in the AIUM test object is

A

1.54 mm/microsec

39
Q

At what location in a sound beam is the SPTA intensity the highest

A

The focal point

40
Q

True or False: Mirror image artifact is often seen around the pancreas

A

False

41
Q

How is range ambiguity artifact eliminated

A

Lower the PRF

42
Q

Side lobes are caused by the use of

A

single crystal transducers

43
Q

Grating lobes are caused by the use of:

A

Arrays

44
Q

A mirror image artifact is a result of the machine’s assumption that

A

Sound travels directly to the reflector and then back to the transducer

45
Q

True or False: With transient cavitation, the bubble bursts.

A

True

46
Q

When producing an ultrasound image, all of the following assumptions are made except

A

all structures create reflections of equal magnitude

Physics Final Flashcards (6 decks)

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