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ECNU - CCE Examination > The History Of Ultrasound And Physics > Flashcards

The History Of Ultrasound And Physics Flashcards

1
Q

What is active sonar?

A

‘Ping’

Reflection of sound waves

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2
Q

What is passive sonar?

A

Just listening

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3
Q

What is acoustic impedance?

A

Density, stiffness and speed of sound.

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4
Q

Where does reflection of sound occur?

A

Occurs at boundaries of impedance

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5
Q

Does sound travel in a vacuum?

A

No

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6
Q

What four qualities of the transmitting medium influence sound transmission?

A
  • Density
  • Stiffness
  • Acoustic Impedance
  • Speed of sound
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7
Q

Do waves carry energy or matter?

A

Energy

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8
Q

How do sound waves propagate?

A

Sound waves propagate by compression and rarefaction of molecules in space.

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9
Q

What is sound frequency?

A

The number of cycles of compression and rarefaction in a sound wave per second (Hz)

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10
Q

What is the definition of the wavelength of sound?

A

The distance travelled in one second.

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11
Q

What is the definition of spatial pulse length?

A

Cycle length multiplied by number of cycles per pulse.

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12
Q

What is spatial pulse length a determinant of?

A

It’s a determinant of axial (in line of beam) resolution (1/2 SPL)

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13
Q

What is the duty factor percentage?

A

The time spent generating pulse (usually 1% - while 99% of the time is spent listening for signal return).

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14
Q

What is the definition of pulse repetition frequency?

A

The number of pulses (send/listen cycles) sent per second.

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15
Q

What is pulse repetition frequency dependent on?

A
  • Speed of sound

- Target depth

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16
Q

Which has better depth penetration…

Lower or higher frequency?

A

Lower frequency

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17
Q

Which has better resolution…

Lower or higher frequency?

A

Higher frequency

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18
Q

Is the speed of sound through a transmitting material affected by frequency?

A

No

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19
Q

Is the speed of sound through a transmitting material affected by wavelength?

A

No

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20
Q

Is the speed of sound through a transmitting material affected by stiffness of the material?

A

Yes

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21
Q

Does the speed of sound through a transmitting material increase or decrease with increased stiffness of the material?

A

Increases

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22
Q

Is the speed of sound through a transmitting material affected by density of the material?

A

Yes

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23
Q

Does the speed of sound through a transmitting material increase or decrease with increased density of the material?

A

Decreases

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24
Q

Is the speed of sound constant for a given tissue?

A

Yes

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25
Q

What is the propagation velocity of sound through bone?

A

4080

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26
Q

What is the propagation velocity of sound through muscle?

A

1580

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27
Q

What is the propagation velocity of sound through liver?

A

1550

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28
Q

What is the propagation velocity of sound through soft tissue (average)?

A

1540

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29
Q

What is the propagation velocity of sound through kidney?

A

1560

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30
Q

What is the propagation velocity of sound through blood?

A

1570

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31
Q

What is the propagation velocity of sound through fat?

A

1450

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32
Q

What is the propagation velocity of sound through water?

A

1480

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33
Q

What is the propagation velocity of sound through air?

A

330

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34
Q

Is there an echo if two tissues have the same acoustic impedance?

A

No

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35
Q

Is there an echo if two tissues have similar acoustic impedance?

A

Weak echo

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36
Q

Is there an echo if two tissues have very different acoustic impedances?

A

Strong echo

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37
Q

Do most tissues have a heterogeneous or homogeneous acoustic impedance?

A

Heterogeneous impedance

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38
Q

Does homogeneous medium reflect sound?

A

No

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39
Q

What kind of echo does a cyst have?

A

No echo (anechoic)

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40
Q

What is reflection of sound?

A

Redirection of a portion of a sound beam back at the interface of tissues of unequal acoustic impedance.

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41
Q

The greater the difference in impedance, the _______ the reflection.

A

Greater

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42
Q

What are the two categories of reflection?

A
  • Specular (mirror like e.g. diaphragm)

- Diffuse (soft tissue e.g. neck ultrasound)

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43
Q

What is specular reflection dependent on?

A

Angle of incidence

44
Q

In diffuse reflection are the adjacent structures smaller or larger than wavelength?

A

Smaller

45
Q

What does A-mode of thyroid stand for?

A

Amplitude (strength of echo)

46
Q

Is A-Mode one dimensional or two dimensional?

A

One dimensional

47
Q

Is B-Mode one dimensional or two dimensional?

A

Two dimensional

48
Q

When was A-Mode used?

Years

A

1960’s

49
Q

When was B-Mode used?

Years

A

Mid 1960s

50
Q

Is the ‘Halo Sign’ an indicator of a benign or malignant nodule?

A

Benign

51
Q

Microcalcifications…

Benign or malignant?

A

Malignant

52
Q

Name four reflection artifacts.

A
  • Shadowing and enhancement
  • Edge artifact
  • Reverberation artifact
  • Comet tail artifact
53
Q

Name one refraction artifact.

A

Phantom image

54
Q

What is the propagation artifact due to?

A

Displacement due to differences in speed of sound.

55
Q

What causes shadowing?

A

When sound passes through a strong attenuator.

56
Q

Which one is lateral…

Sternohyoid or sternothyroid?

A

Sternothyroid

57
Q

Which one is medial…

Sternohyoid or sternothyroid?

A

Sternohyoid

58
Q

Enhancement is seen behind cysts.

True or false?

A

True

59
Q

Eggshell calcification - what kind of artifact is it?

A

Reflection artifact

60
Q

Comet tail artifact is also called…

A

Ring down artifact

61
Q

What is refraction?

A

Bending of wave at an interface when angle of incidence is not 90 degrees.

62
Q

What is the degree of refraction proportional to?

A

The difference between the speed of sound in each tissue.

63
Q

What may happen when a refracting object exists in the path of the US beam?

A

A second ‘ghost’ image may appears.

64
Q

What three things does attenuation of acoustic energy result from?

A
  • Reflection
  • Scatter
  • Absorption
65
Q

What is attenuation dependent on?

A

Frequency

66
Q

Do higher or lower frequencies have greater attenuation?

A

Higher frequencies

67
Q

What gives greater depth of imaging? Higher or lower frequencies?

A

Lower frequencies

68
Q

What artifacts occur due to attenuation?

A
  • Shadowing

- Enhancement

69
Q

Resolution:

Lateral…

A

Side to side

70
Q

Resolution:

Azimuthal…

A

Up-down

71
Q

Resolution:

Axial…

A

Distance from transducer

72
Q

What determines lateral and azimuthal resolution?

A

Focused beam width

73
Q

What is the Fresnal Zone?

A

Near field

74
Q

What is the Fraunhofer Zone?

A

Far field

75
Q

Where is the area of maximal narrowing?

A

Focal zone

76
Q

What happens to intensity in the far field?

A

Intensity is fairly uniform

77
Q

What happens to intensity in the near field?

A

Large variations of intensity

78
Q

What is the far field also called?

A

Fraunhofer Zone

79
Q

What is the near field also called?

A

Fresnel Zone

80
Q

What determines axial resolution?

A

Pulse duration

81
Q

What is axial resolution =

A

1/2 x Spatial Pulse Length

82
Q

What is the spatial pulse length?

A

Numbers of cycles in the pulses x wavelength

83
Q

Does axial resolution increase with increasing or decreasing frequency?

A

Increasing frequency

84
Q

Is the depth of the focal zone adjustable?

A

Yes

85
Q

What frequency (higher or lower) do you use if you want to better visualize superficial structures?

A

Higher

86
Q

What frequency (higher or lower) do you use if you want to better visualize deep structures?

A

Lower

87
Q

What does a transducer do?

A

Converts one form of energy to another.

88
Q

What is the Piezoelectric Effect?

A

Property of some crystals to emit electricity when compressed.

89
Q

What are the three types of transducers?

A
  • Linear Array
  • Curved Array
  • Phase Array
90
Q

Multiple crystals in a linear array allow real time scanning with a stationary transducer.

True or false?

A

True

91
Q

Advances in Technology - Signal Processing.

Two types of image enhancement?

A
  • Noise reduction

- Edge sharpening

92
Q

Advances in Technology - Signal Processing.

Two results of CT and MRI reconstruction algorithms…

A
  • Beam steering

- Spatial compounding

93
Q

At higher power tissue will reverberate and produce harmonics of the original frequency.

True or false?

A

True

94
Q

What does tissue harmonic imaging involve?

A

Selective detection of second harmonic.

95
Q

Selective detection of harmonic leads to increased contrast.

True or false?

A

True

96
Q

Name two advantages of tissue harmonic imaging.

A
  • Increased conspicuity

- Improved signal to noise for deeper structures

97
Q

What algorithm does panoramic image reconstruction (extended field of view) use?

A

‘Pattern Matching’ Algorithm

98
Q

The gain can be adjusted on the ultrasound machine.

True or false?

A

True

99
Q

What is time gain compensation?

A

Multiple channels corresponding to depth

100
Q

Can the focal zones on an ultrasound machine be adjusted?

A

Yes

101
Q

What two parameters are focal zones on an ultrasound machine adjusted by?

A
  • Depth

- Number

102
Q

Where are images from ultrasound machine usually stored?

Name three

A
  • Hard drive
  • CD
  • DVD
103
Q

What two formats are images stored in?

A
  • TIFF

- JPG

104
Q

What two things is resolution dependent on?

A
  • Frequency

- Beam focal width

105
Q

What are the items to consider when selecting an ultrasound system?

(6 items)

A
  • Resolution and image clarity
  • Portability
  • Doppler capability
  • Storage capacity
  • Speed
  • Ease of connection of peripheral devices

ECNU - CCE Examination (13 decks)

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