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physics doppler final > doppler final > Flashcards

doppler final Flashcards

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1
Q

when color gain is set to an inappropriately high level, color appears throughout the color box. A term that describes this is called______________

A

color confetti

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2
Q

Multiple utrasound pulses that are used to accurately determine blood velocities are called ___________

A

ensemble

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3
Q

A wall filter is used to eliminate high frequency Doppler shifts from moving anatomy rather than from moving blood cells. TorF

A

False

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4
Q

The 3 basic forms of blood flow are:

A

pulsatile, phasic, and steady

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5
Q

The Reynolds number for turbulent flow is greater than 2,000. TorF

A

True

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6
Q

Which technique is used to perform spectral analysis on color Doppler data?

A

autocorrelation

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7
Q

Velocity mode distinguishes laminar flow from turbulent flow. TorF

A

False

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8
Q

What are the 2 things that are correct about pulsed Doppler transducers?

A

at least 1 crystal and lower sensitivity

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9
Q

The _____________ frequency is the highest Doppler frequency that can be measured without the appearance of aliasing

A

Nyquist

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10
Q

What is the most common error with Doppler ultrasound?

A

Aliasing

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11
Q

The Law of Conservation of Energy states that the pressure is lowest at _________

A

the stenosis

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12
Q

The phasic and steady flow are present in venous circulation. TorF

A

True

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13
Q

Simultaneous anatomic imaging and Doppler is called

A

duplex imaging

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14
Q

Doppler shift is inversely related to the frequency of the transmitted sound. TorF

A

False

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15
Q

When the blood cells are moving __________ to the sound beam, the entire velocity is measured.

A

parallel

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16
Q

Turbulent flow profiles may be seen _______ from a significant stenosis in a vessel.

A

downstream

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17
Q

Flow increases when either

a. pressure gradient increases and resistance decreases
b. resistance increases
c. pressure gradient decreases

A

a.

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18
Q

Assume that a doppler study is performed and the Doppler shift is 6kHz when the blood’s velocity is 2m/s. If the blood velocity slows to 1m/s. What will the Doppler shift be?

A

3kHz

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19
Q

_____________ is defined by a magnitude and a direction.

A

velocity

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20
Q

This process extracts the low Doppler frequency form the transducers carrier frequency.

A

demodulation

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21
Q

The lumen of a horizontal vessel evaluated with a color doppler, sector shaped image contains a single color. TorF

A

False

22
Q

If a patient is supine what is the arterial pressure at the knee?

A

140mmHg

23
Q

Tissue vibration associated with turbulence is called a

A

thrill

24
Q

Transducer frequencies of ___________ Doppler shifts range are used since they are audible

A

20Hz-20,000Hz

25
Q

Cosine 0 degrees is 1 indicating flow _____________ the transducer, whereas cosine 180 degrees is -1 indicating flow __________ from the transducer.

A

toward, away

26
Q

All of the following occur during expiration except

a. venous flow in the legs increases
b. the diaphragm rises into the thoracic cavity
c. venous return to the heart decreases
d. abdominal pressure increases

A

d. abdominal pressure increases

27
Q

What is the hydrostatic pressure of the waist if the person is standing?

A

50 mmHg

28
Q

Blood moving from regions of higher energy to lower energy is called what

A

energy gradient

29
Q

Velocity mode color Doppler and variance mode color Doppler will produce identical images when blood flow patterns are turbulent. TorF

A

False

30
Q

Velocity mode color Doppler and variance mode color doppler will produce identical images when blood flow patterns are laminar. TorF

A

True

31
Q

Absence of color on a color Doppler image always indicates a region of no blood flow. TorF

A

False

32
Q

During a pulsed Doppler exam, aliasing is observed. Al of the following may eliminate aliasing except.

a. selection of another imaging view with a shallower sample volume
b. selection of another transducer with a lower frequency
c. selection of another imaging view that provides a greater pulse repetition period
d. use of a continuous wave system

A

C.

33
Q

The highest Doppler frequency without the appearance of aliasing is called the ___________ and is equal to ________.

A

Nyquist limit, half of the emitted PRF

34
Q

The higher the pulse repetition frequency of a doppler exam, the more likely aliasing is to occur. TorF

A

False

35
Q

What happens to venous flow in the legs during inspiration?

A

decreases

36
Q

The Reynolds number for laminar flow is less than

a. 1500
b. 1200
c. 1000

A

a 1500

37
Q

__________ in a fluid system is called voltage. Similarly, _________ in a fluid system is called a current.

A

pressure, flow

38
Q

What is the arterial pressure measured at the patients knee who is standing and the hydrostatic blood pressure is 140 mmHg?

A

c. 215mmHg (140+75)

39
Q

During expiration, the diaphragm moves UP or DOWN

A

UP

40
Q

Gravitational energy is a form of ____________ energy

A

stored

41
Q

___________ energy loss in blood is determined by the hematocrit.

A

viscous

42
Q

Parabolic flow is the velocity in the center of the lumen and gradually decreases to its minimum at the vessel wall. TorF

A

True

43
Q

An advantage of power mode doppler is

A

unaffected by doppler angles

44
Q

Ghosting artifact show up only on spectral doppler. TorF

A

False

45
Q

Color Doppler will have crosstalk as an artifact. TorF

A

False

46
Q

Wall filters are used to eliminate low frequency Doppler shifts from moving anatomy. TorF

A

True

47
Q

What is the current method of processing Doppler signals that can distinguish laminar and turbulent flow?

A

FFT

48
Q

Which of the following terms is synonymous with spectral broadening?

A

turbulent flow

49
Q

Supine means that your are ____________

A

laying flat on your back

50
Q

Stenosis will have increased velocity within the stenosis. TorF

A

True

physics doppler final (1 decks)

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