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Ultrasound Physics chapter 1-3 > chapter 1-3 > Flashcards

chapter 1-3 Flashcards

1
Q

frequency

A

cycles per second hertz

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2
Q

amplitude

A

Measures from middle or undisturbed, value to the maximum value

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3
Q

wavelength

A

distance or length of one complete cycle

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4
Q

human hearing

A

20hz-20kHz

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5
Q

high frequency

A

more cycles per second- better resolution but less penetration

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6
Q

lower frequency

A

less cycles per second- less resolution but more penetration

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7
Q

Pulse waves

A

pulse allow the ultrasound crystals to “talk” during the generation of sound and to “listen” between pulses

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8
Q

Unrelated

A

Two items that are not associated

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9
Q

related

A

two items that are associated or affiliated. Does not have to be specific

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10
Q

Directly related or directly proportional

A

two items that are associated such that when one item increases, the other increases. lower left to upper right

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11
Q

inversely related or inversely proportional

A

one item increases, the other decreases. upper left to lower right

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12
Q

reciprocal relationship

A

two numbers with a reciprocal relationship are multiplied together the result is 1. when one increases the other decreases

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13
Q

units of length

A

distance, circumference: cm, feet

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14
Q

units of area

A

cm2, ft2

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15
Q

units of volume

A

cm3, ft3

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16
Q

positive exponents has a value

A

greater than 10

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17
Q

negative exponents has a value

A

less than 1

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18
Q

exponents of zero has a value

A

Between 1 and 10

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19
Q

if we speak of frequency

A

talking about MEGAhertz

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20
Q

if we speak about period

A

talking about MICROseconds

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21
Q

tissue is also known as

A

media-medium

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22
Q

sound is a

A

mechanical wave

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23
Q

compressed

A

squeezed together

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24
Q

rarefield

A

stretched apart

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25
Q

sound travels in

A

a straight line

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26
Q

sound waves are

A

Longitudinal waves

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27
Q

Acoustic propagation propereties

A

effects of the medium upon the sound wave

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28
Q

biologic effects

A

effects of thee sound wave upon the biologic tissue through which it passes

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29
Q

what are the three acoustic variables

A

pressure, density, distance

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30
Q

Pressure

A

concentration of force in an area

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31
Q

what are the units of pressure

A

Pascals (Pa)

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32
Q

Density

A

concentration of mass in a volume

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33
Q

what are the units of density

A

kg/cm3

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34
Q

Distance

A

measure of particle motion

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35
Q

what are the units of distance

A

cm, feet, miles

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36
Q

sound waves are also known as

A

acoustic waves

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37
Q

Transverse waves

A

perpendicular to the direction that the wave propagates

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38
Q

longitudinal waves

A

particles move in the same direction that the wave propagates.

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39
Q

sound is what kind of wave?

A

Longitudinal wave

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40
Q

in-phase waves

A

when their peaks occur at the same time and at the same location. “in-step”

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41
Q

out-of-phase

A

their peaks occur at different times, so do their troughs. “out-of-step”

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42
Q

interference

A

waves lose their individual characteristics at that moment and combine to form a single wave

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43
Q

constructive interference

A

wave is larger than either of its comonents

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44
Q

destructive interference

A

resultant wave is smaller than one of its comonents

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45
Q

both constructive and destructive interference occur when

A

frequencies of the wave differ

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46
Q

parameters

A

describe features of a sound wave

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47
Q

source

A

a sound wave is the ultrasound system and transducer

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48
Q

Period

A

is the time it takes a wave to vibrate a single cycle

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49
Q

units of Period

A

time, microseconds,seconds, hours, days

50
Q

Typical value of Period

A

0.06-0.5 Microseconds
6x10^-8 to 5x10^-7
0.06 to 0.5 micros
0.00000006 to 0.0000005 seconds

51
Q

Period is Determined by

A

sound source

52
Q

can a Sonographer adjust Period?

A

NO

53
Q

Frequency

A

the number of particular events that occur in a specific duration of time. the number of cycles that occurs in one second

54
Q

what are the units of frequency

A

per second, 1/second=1 hertz
1,000 cycles/second=1 kHz
1,000,000 cycles/second=1 MHz

55
Q

Typical value of Frequency

A

2 MHz-15MHz
2 million-15 million per second

56
Q

Frequency is determined by

A

sound source

57
Q

is Frequency adjustable?

A

NO

58
Q

Frequency of infrasound

A

less than 20 Hz

59
Q

Frequency of Audible sound

A

between 20 Hz and 20 KHz

60
Q

Frequency of Ultrasound

A

Greater than 20 KHz (20,000Hz)

61
Q

Frequency is important to ultrasound because

A

it affects penetration and image quality

62
Q

Period and frequency are

A

inversely related to each other

63
Q

period and frequency have a specific relationship called

A

reciprocal

64
Q

Hertz means

A

events per seond

64
Q

What are the three Bigness parameters

A

Amplitude, Power, Intensity

65
Q

Amplitude

A

Bigness of a wave.
Difference between the maximum value and the average or undisturbed value of an acoustic variable. Difference between the minimum value and the average value of the acoustic variable

66
Q

Units of Amplitude

A

Pressure- Pascals
Density- g/cm3
Particle motion- cm, inches-any distance
Decibels (dB)

67
Q

typical values of Amplitude

A

1 million pascals (1 MPa) - 3 million pascals ( 3 MPa)

68
Q

Amplitude is determined by

A

sound source

69
Q

Can amplitude be adjustable?

A

Yes, allows the Sonographer to alter initial amplitude of a wave

70
Q

Power

A

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

71
Q

Units of Power?

A

Watts

72
Q

What is the typical values of Power?

A

0.004-0.090 watts
(4 - 90 milliwatts)

73
Q

Amplitude and power are related how?

A

describe the size or magnitude of a wave.

74
Q

squared

A

number is multiplied by itself

75
Q

Power is determined by?

A

Sound source

76
Q

is Power adjustable?

A

Yes, Allows Sonographer to alter the initial power of a wave

77
Q

Intensity

A

concentration of energy in a sound beam

78
Q

what are the units of intensity?

A

Watts/square centimeter, W/cm2
watts form power and cm2 from beam area

79
Q

what are the typical values of intensity?

A

0.01-300 W/cm2

80
Q

how is intensity determined by?

A

sound source

81
Q

Is intensity adjustable?

A

Yes, alters the initial intensity of a wave

82
Q

intensity formula

A

intensity (w/cm2)=power(w) / area(cm2)

83
Q

Amplitude, power, and intensity describe what?

A

magnitude or strength of a wave. Directly Related

84
Q

is intensity proportional to power?

A

YES

85
Q

relationship between intensity and amplitude?

A

intensity is proportional to the wave’s amplitude squared

86
Q

Wavelength

A

distance or length of one complete cycle

87
Q

units of a wavelength

A

mm, meters, or any other unit of length

88
Q

typical value of wavelength

A

0.1-0.8 mm

89
Q

Wavelength is determined by

A

BOTH the Source and the Medium

90
Q

can you adjust wavelength?

A

NO

91
Q

in soft tissue, sound with a frequency of 1 MHz has a wavelength of

A

1.54 mm

92
Q

sound with a frequency of 2 MHz has wavelength of

A

0.77 mm in soft tissue

93
Q

Wavelength formula

A

wavelength (mm) =1.54 mm/milliseconds/ frequency (MHz)

94
Q

Shorter wavelengths are created by

A

high frequency sound

95
Q

higher quality images have

A

greater detail

96
Q

Propagation speed

A

rate at which a sound wave travels through a medium

97
Q

what are the units of Propagation speed

A

meters per second, mm/ms, or any distance divided by time

98
Q

what are the typical values of propagation speed?

A

500 m/s-4000 m/s depending on the tissue

99
Q

propagation speed is determined by

A

medium through which the sound is traveling

100
Q

is propagation speed adjustable?

A

NO

101
Q

Biologic medium is called

A

soft tissue

102
Q

the speed of sound in soft tissue is

A

1,540 m/s
1.54 mm/ms
1.54km/s
1 mile per second

103
Q

sound travels fastest in

A

solids

104
Q

sound travels slower in

A

liquid

105
Q

sound travels slowest in

A

gases

106
Q

Speed formula

A

speed (m/s) = frequency (Hz) x wavelength (m)

107
Q

Two characters of Medium affect speed of sound

A

stiffness, density

108
Q

Stiffness

A

ability of an object to resist compression

109
Q

how does stiffness affect speed?

A

stiffness and speed are directly related

110
Q

Bulk modulus

A

stiffness

111
Q

Elasticity and compressibility are

A

the opposite of stiff

112
Q

how does density affect speed?

A

Density and speed are inversely related

113
Q

Stiffness has the greatest influence on

A

speed

114
Q

sound travels slowly through

A

air

115
Q

slowest to fastest propagation speeds

A

air
lung
fat
soft tissue/blood
tendon
bone

116
Q

Pulse duration

A

Actual time from the start of aa pulse to the end of that pulse. Single transmitted, talking or on time

117
Q

Units for pulse duration

A

Time: Microseconds

118
Q

typical values of pulse duration

A

0.3-2.0 microseonds

119
Q

pulse duration is determined by

A

sound source

120
Q

is pulse duration adjustable?

A

NO

Ultrasound Physics chapter 1-3 (5 decks)

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