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DMSO Physics > final review from canvas file > Flashcards

final review from canvas file Flashcards

1
Q

Which is larger macro or micro

A

macro means bigger

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2
Q

symbol for millions

A

mega

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3
Q

symbol for millionths

A

micro

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4
Q

symbol for hundreds

A

hecto

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5
Q

symbol for hundreths

A

centi

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6
Q

a frequency of 15,000 hz is

A

audible sound

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7
Q

if power in a wave is halved the intensity is reduced to

A

half

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8
Q

if the amplitude of a wave is increased 3 times, the intensity is increased by

A

9 times

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9
Q

propagations speed is determined by

A

medium

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10
Q

propagations speed increases as frequency increases or decreases

A

false

not realated

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11
Q

how many intensities are needed to calculate decibels

A

two

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12
Q

path length increases what happens to the attenuation

A

increases

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13
Q

which is lower spatial peak or spatial average intensity

A

spatial average

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14
Q

in addition to location in a beam, intensities also vary with

A

time

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15
Q

the most important intensity in soft tissue is

A

SPTA

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16
Q

duty factor is a unitless number between

A

0 and 1

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17
Q

intensities may be reported in various ways in respect to

A

time and space

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18
Q

duty factor for a pulsed ultrasound system is typically

A

0.2%

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19
Q

beam intensity is the same at different depths and lateral locations

true/false

A

FALSE

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20
Q

at a particular depth the center of a beam is more intense than the edges

true/false

A

TRUE

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21
Q

temporal peak is the maximum intensity in

A

time

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22
Q

3 MHz is how many Hz

A

3 million

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23
Q

how much bigger is a billion than a million

A

1000

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24
Q

what are the units of a wavelength

A

mm

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25
Q

what are the units of frequency

A

Hz

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26
Q

what are the units of intensity

A

w/cm^2

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27
Q

what are the units of propagatoin speed

A

m/s

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28
Q

what are the units of period

A

us

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29
Q

what is determined by sound source

A

period

frequency

amplitude

power

intensity

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30
Q

if the intensity is the same while the power is doubled what happens to the beam area

A

increases

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31
Q

sound beam travels a total of 10cm in 2 sec. What is the speed of sound in this medium

A

5 cm/sec

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32
Q

what term describes the time from the start of a pulse to the end of the pulse

A

pulse duration

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33
Q

PRF is the recipricol of

A

PRP

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34
Q

dB is a mathmatical representatoin with a __________scale

A

logarithmic

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35
Q

rayleigh scattering is related to

A

frequency^4

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36
Q

which media has the greatest attentuatoin and slowest speed

A

Air

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37
Q

what mathmatically describes the physics of refraction

A

snells law sin (tran)/ sin(inc)= speed 2/speed 1

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38
Q

two PZT crystals are made from the same material. The thicker will have a pulse transducer with

A

lower frequency and slower speed

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39
Q

when PZT exceeds the curie point the PZT

A

depolarizes

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40
Q

PZT is also known as

A

crystal, active element, ceramic

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41
Q

what reduces the ringing in a transducer

A

backing material

42
Q

mathmatically the Q factor is the frequency divided by the

A

bandwidth

43
Q

imaging transducers are also referred to as

A

pulsed wave transducer

44
Q

what type of crystal will produce sound with the lowest freq

A

thick and slow

45
Q

the damping material in the transducer improves the systems what resolution

A

axial

46
Q

if the electrical excitation volt is 6MHz then the output freq of a CW transducer is

A

6 MHz

47
Q

the impedance of a transducer active element is 19Mrayls, and the impedance of the skin is 14Mrayls. What is an acceptable impedance for the matching layer

A

anything between 14 and 19 Mrayls

48
Q

which transducer component is a thin barrier of cork or rubber that isolates or uncouples the internal components from the case

A

acoustic insulator

49
Q

what is the purpose of the backing material in an imaging transducer

A

reduce ringing and improve axial resolution

50
Q

what creates the beam with deepest focus

A

large diameter and high freq

51
Q

how are freq and near zone length related

A

directly, lower freq shorter near zone

52
Q

what crystal creates the least divergence

A

large diameter higher freq

53
Q

what creates the most divergence

A

small diameter

lower frequency

54
Q

what determines the freq of sound created by a pulsed transducer

A

thickness and speed of the PZT

55
Q

what determines the spread of a sound beam in the far field

A

diameter of crystal and frequncy

56
Q

frequency does not change, if the diameter of the new PZT increases what happens to the wavelength

A

no change

57
Q

imaging to greater depths requires the listeing time to

A

increases

58
Q

when reporting a beams intensity the maximum is referred to as

A

SPTP

59
Q

the highest temporal intensity is

A

temporal peak

60
Q

units for reporting intensity are

A

w/cm^2

61
Q

what is measured where intensity is maximum and averaged over time

A

SPTA

62
Q

which intesity is measureed over the entire cross section of the beam and over all time

A

SATA

63
Q

what is the same as normal incidence

A

perpendicular, orthogonal, right angle, 90 degrees

64
Q

intensity of a sound beam just prior to striking a boundry is referred to as

A

incident intensity

65
Q

the portion of a sound beam that contimnues on after striking a boundry is the

A

transmitted intensity

66
Q

the percentage of US intensity that is allowed to pass through when the beam reaches a boundry between two media is referred to as

A

intensity transmission coefficient

67
Q

a sound beam with an intensity of 50 w/cm^2 strikes a boundry and is totally reflected. What is the intensity reflectoin coefficient

A

100%

68
Q

the intensity reflection coefficient of sound is 99.9% . What percentage is transmitted into the body

A

0.1%

69
Q

specular reflections arise when the interface is

A

smooth

70
Q

what do we know about oblique incidence

A

nothing

71
Q

transmission with a bend is

A

refraction

72
Q

Snells law describes what physics

A

refraction

73
Q

sound waves strike a boundry at normal incidence. The impedances of the two are identical. What percentage of the beam is reflected

A

0%

must be difference in impedance for reflection to occur

74
Q

what processes occur as the ultrasound passes through all media

A

reflection, scattering and absorption

75
Q

two waves are traveling through a medium and arrive at a location at the same time. What event takes place

A

interference

76
Q

the percentage of time that a system is transmitting a pulse is referred to as

A

duty factor

77
Q

a 3MHz beam travels though two media. It attentuates 5 dB in A and 6 dB in B.

What is the total attenuation of the beam

A

11 dB

78
Q

what is the dominant factor in attenuation

A

absorption

79
Q

impedance is a characteristic of

A

acoustic resistance of sound traveling in media

density x propagation speed

80
Q

hertz is a unit used to describe what wave characteristic

A

frequency

81
Q

a low freq transducer is best at imaging what structures? Deep or shallow

A

deep

82
Q

The percentage of the US intensity that is allowed to pass through when the beam reaches a boundary between two media is

A

intensity transmission coefficient

83
Q

what is the best estimate for attenuation coefficient of sound traveling in soft tissue

A

.5 dB/cm/MHz

84
Q

Attenuation is determined by two factors

A

path length and freq of sound

85
Q

With longer distances and higher frequencies you have

A

higher attenuation

86
Q

With shorter distances and lower frequencies you have

A

lower attentuation

87
Q

Because attenuation means a weakening or a decrease, the dbs must be

A

negative

88
Q

Which term best describes redirection of sound in many directions

A

scattering

89
Q

Reflections from a smooth reflector are referred to as

A

specular

90
Q

When a boundary is rough, reflected sound is disorganized and random, also called

A

diffuse or backscatter

91
Q

Rayleigh scattering increases dramatically with increasing frequency, which is the relation

A

frequency 4

92
Q

Acoustic Impedance is equal to

A

density x propagation speed

93
Q

The time needed for a pulse to travel to and from the transducer and the reflector is called

A

go return time, time of flight,

94
Q

A sound wave is created by the transducer, reflects off an object and returns to the transducer in 52, what is the reflector depth and total distance traveled

A

4 cm depth and 8 cm total travel

95
Q

The maximum imaging depth during an ultrasound exam is 5 cm. The sonographer adjusts the depth to 10cm.

What happens to pulse repetition frequency

A

PRF is halved

96
Q

A sound wave is created by the transducer, reflects off an object, and returns to the transducer. The time of flight is 130 microseconds. What is the maximum PRF

A

7,700 Hz

97
Q

A sound wave is created by the transducer, reflects off an object, and returns to the transducer. The go return time is 39 microseconds. What is the total distance traveled

A

6 cm

98
Q

Axial resolution deals with structures that are ___________to the sound beam

A

parallel

99
Q

As frequency increases, the numerical value of LARRD resolution

A

lowers

100
Q

Superior axial resolution is associated with the following

A

shorter spatial pulse length, shorter pulse duratoin, higher Freq, fewer cycles per pulse, lower numerical values

DMSO Physics (16 decks)

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