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VascularPhysics > Chapter 3 > Flashcards

Chapter 3 Flashcards

1
Q

Define Period

A

the time is takes a wave to vibrate a single cycle

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2
Q

What unit is Period reported in?

A

Units of time (microseconds, seconds)

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3
Q

What is the typical value of the period in diagnostic ultrasound?

A

0.06 to 0.5 microseconds

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4
Q

Is the Period determined by the source, the media, or both?

A

the source only

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5
Q

Can the Period be adjusted by the sonographer?

A

Nope

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6
Q

Define Frequency

A

the number of events that occur in a specific duration of time

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7
Q

What unit is frequency reported in?

A

units per second, 1/sec, Hz

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8
Q

What is the typical value of the frequency in diagnostic ultrasound?

A

2 MHz - 15 MHz

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9
Q

Is the Frequency determined by the source, the media, or both?

A

the source only

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10
Q

Can the frequency be adjusted by the sonographer?

A

nope

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11
Q

What are the range of frequencies audible to humans?

A

20 Hz - 20,000 Hz (20 KHz)

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12
Q

What is the range of frequency used in Diagnostic Ultrasound?

A

2 - 15 MHz

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13
Q

How are frequency and period related to each other?

A

They are reciprocals. f = 1/P and P=1/f

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14
Q

Which of these waves is ultrasonic and most useful in diagnostic sonography?

A. 400 MHz
B. 4 MHz
C. 2 kHz
D. 200,000 Hz

A

B. Only one within diagnostic range

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15
Q

Which of the following waves has the longest period?

A. 2 MHz
B. 4,000 Hz
C. 6 Hz
D. 1 kHz

A

C. This is the lowest frequency, therefore the longest period.

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16
Q

What three parameters describe the size or magnitude of the wave?

A

Amplitude, Power, Intensity

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17
Q

How is Amplitude seen on an ultrasound?

A

Brightness

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18
Q

How do you calculate Amplitude?

A

(Max-Min) / 2 = A

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19
Q

Is Amplitude determined by the source, the media, or both?

A

The source initially, but decreases as the sound propagates.

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20
Q

Is the Amplitude adjustable?

A

Yes

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21
Q

How is Amplitude different from peak-to-peak amplitude?

A

Amplitude is measured the middle to the max or min. Peak-to-peak measures from the min to the max. Therefore peak-to-peak = 2 x amplitude.

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22
Q

Define Power

A

the rate of energy transfer or the rate at which work is performed

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23
Q

What is Power measured in?

A

Watts

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24
Q

How are amplitude and power related?

A

power = amplitude^2. Directly related.

25
Q

What is the term used for amplitude decrease as it travels through tissue?

A

attenuation

26
Q

Is the power determined by the source, media, or both?

A

Source

27
Q

Can the Power be adjusted?

A

yes, of course

28
Q

Which of the following controls affects the power of the sound beam entering the tissue?

A. Output
B. Frequency
C. Depth
D. Focus

A

A. Output

29
Q

Define Intensity

A

the concentration of energy in a sound beam

30
Q

What units are use to measure intensity?

A

watts/ cm^2

31
Q

Is the intensity determined by the source, media, or both?

A

the source

32
Q

How is intensity related to power, amplitude, and area?

A

Intensity = power / area

Direct to power and amplitude
Inverse to area

33
Q

Define Wavelength

A

the distance or length of one complete cycle

34
Q

What are typical wavelength values?

A

0.1 to 0.8 mm

35
Q

Is wavelength determined by the source, media, or both?

A

BOTH

36
Q

Can wavelength by adjusted?

A

No

37
Q

What is the difference between wavelength and period?

A

Wavelength measures the distance of a single cycle.

Period measures the time required to complete a single cycle.

38
Q

What is the wavelength of 1 MHz frequency sound wave in soft tissue?

A

1.54 mm

39
Q

Define propagation speed?

A

the rate at which a sound wave travels through a medium

40
Q

Is the propagation speed determined by the source, media, or both?

A

Medium only!

41
Q

Is propagation speed adjustable?

A

No

42
Q

What is the speed of sound in soft tissue?

A

1,540 m/s

43
Q

What are the terms elasticity and compressibility used to describe?

A

Stiffness

44
Q

How is speed related to stiffness?

A

directly

45
Q

How is speed related to density?

A

inversely

46
Q

Related? Frequency and period

A

Inversely

47
Q

Related? Amplitude and power

A

directly

48
Q

Related? Amplitude and intensity

A

directly

49
Q

Related? Power and intensity

A

directly

50
Q

Related? wavelength and intensity

A

unrelated

51
Q

Related? wavelength and frequency

A

inversely

52
Q

Related? acoustic velocity and density

A

inversely

53
Q

Related? elasticity and speed of sound

A

inversely

54
Q

Related? acoustic velocity and compressibility

A

inversely

55
Q

Related? stiffness and sound speed

A

directly

56
Q

Related? frequency and sound speed

A

unrelated

57
Q

Related? frequency and intensity

A

unrelated

58
Q

Related? power and frequency

A

unrelated

VascularPhysics (12 decks)

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