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Practice > SPI > Flashcards

SPI Flashcards

1
Q

What are the advantages of backing material?

A

Improves axial resolution
Shortens pulse length
Increase bandwidth
Decrease Q factor

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2
Q

Frequency is determined by

A

Thickness of crystal

Prop speed of crystal

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3
Q

Spatial resolution consists of

A

Longitudinal and Lateral resolution

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4
Q

What is longitudinal resolution?

A

Distinguish two structures that are close to each other parallel to the sound beam
•-•. •-•

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5
Q

Longitudinal resolution is improved by?

A

Increased damping material (less ringing)
Higher frequency (shorter pulse)
Shorter wavelength

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6
Q

The longitudinal resolution value ranges from?

A

0.05 to 0.5 mm

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7
Q

What is lateral resolution?

A

Minimum distance that two structures are separated by side-to-side that produce two distinct echos

•
|
•

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8
Q

Lateral resolution is best at the?

A

Near zone length

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9
Q

What improves lateral resolution?

A

Focusing

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10
Q

What is temporal resolution?

A

Read resolution pertaining to time

It is the time spent to make a frame

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11
Q

What is frame rate?

A

The number of frames ultrasound machine displays in one second

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12
Q

Frame rate is good for what type of resolution?

A

Temporal resolution

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13
Q

As temporal resolution increases image quality what resolution decreases?

A

Spatial resolution

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14
Q

If less time is needed to create an image the frame rate will?
While temporal resolution?

A

Increase

Improves

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15
Q

What improves temporal resolution?

A

Single focus transducer
Less depth of penetration
Narrow sector angle
Less line density (less scan line)

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16
Q

Gain is a ratio of

A

Output and input electrical power

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17
Q

What is contrast resolution?

A

Described as ability to distinguish between slightly different shades of gray

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18
Q

Dynamic range is also known as

A

Compression

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19
Q

What is dynamic range?

A

Ratio in dB from largest to smallest power that a system can handle

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20
Q

A wide dynamic range displays more?

A

Shades of gray

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21
Q

A narrow dynamic range results in more

A

Black and white appearance of the image

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22
Q

What is bandwidth?

A

A range of frequencies below and above the main frequency.

it is the difference between the highest and lowest frequency emitted from transducer

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23
Q

A wide bandwidth is created from a

A

Short pulse

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24
Q

A short pulse is created by the use of more

A

Damping material

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25
Q

The damping process on transducer

A

Decreases PD
Decreases SPL
Shorter pulses produce less ringing

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26
Q

What is quality factor?

A

Unitless number that represents the degree of damping

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27
Q

What is the formula for Q factor?

A

Q= operating frequency/ BW

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28
Q

What is specular reflection?

A

Very smooth
Flat boundary
Wavelength is larger compared to the boundary roughness
Create grayscale image artifact called mirror

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29
Q

What is non specular or diffuse scattering?

A

Very rough
Irregular borders
When wavelength is smaller compared to the boundary roughness

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30
Q

In soft tissue the depth of penetration decreases when

A

Frequency increases

Attenuation coefficient increases

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31
Q

Half layer thickness depends on the

A

Frequency of sound

Medium through which a sound is propagating

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32
Q

What is impedance?

A

Is the acoustic resistance a countered when sound travels propagates through the medium

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33
Q

What is the formula for impedance?

A

Z= p x c

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34
Q

What is incidence?

A

Angle between incidence and direction in a line perpendicular to or oblique to the boundary of the medium

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35
Q

What is perpendicular incidence?

A

Boundaries between media with and different impedance has part of the sound is reflected in part is transmitted

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36
Q

Incident intensity is?

A

Intensity that the sound wave has before it hits a boundary

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37
Q

What is reflected intensity?

A

Remains after hitting the boundary and a second return back in the same direction that it came from

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38
Q

What is transmitted intensity?

A

Intensity that continues the path after striking the boundary through the second medium

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39
Q

Oblique incidence is?

A

Not at right angle

Not 90 degrees

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40
Q

Reflection can only be calculated with

A

Normal incidence

Different impedances

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41
Q

Refraction occurs with

A

Oblique incidences

Different prop speeds

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42
Q

Transmission occurs with

A

Normal or oblique incidence

43
Q

What is specular reflection?

A

Two media are smooth

Wavelength is small compared to the boundary dimension

44
Q

What is speckle artifact?

A

Displayed dot that does not represent scatters

45
Q

What is persistence button?

A

Average has consecutive frames for produces a smoother image

46
Q

What is Fast Fourier Transform?

A

Range if velocities found in beam

47
Q

When does aliasing occur?

A

When Doppler shift exceeds the Nyquist limit which is one half of PRF

48
Q

How to correct aliasing?

A 
Decrease the baseline
Increase scale
Increase Doppler effort (angle) 
Increase the frequency
Switch to cw
49
Q

What does color Doppler imaging or color flow image use?

A 
Determines presence of flow
Direction of flow
Type of vessel
Flow characteristic (laminar, turbulent)
Absence of flow (testicular torsion)
Increase perfusion (possible malignancy)
Determine if it is a cystic structure or vessel
50
Q

Color power doppler or ultrasound angio or color Doppler energy or color power angio is?

A

Color flow display according to strength.

Free of aliasing, not angle dependent, high sensitivity to flow in small vessels

51
Q

What is color Doppler?

A

Pulsed wave
Changing color means velocity change or aliasing
Information about velocities
Velocities converted into color

52
Q

What is color bar?

A

Color used to describe flow velocity

53
Q

Where is the color bar located?

A

Upper left side of screen

54
Q

The higher the position of color on the bar

A

Greater velocity flow of RBC toward transducer

55
Q

The lower the position of color on the bar

A

Greater velocity away from the transducer

56
Q

What are the two types of modes on the color bar?

A

Velocity mode

Variant mode

57
Q

What is velocity mode?

A

Multiple velocity such as red, black, blue

58
Q

What is variance mode?

A

Measure spectral (color)

59
Q

In color Doppler absence of green means?

A

Velocities are the same

60
Q

In color Doppler the presence of green means?

A

Change in velocity or presence of turbulence

61
Q

What is color flow processing?

A

Velocity detection for color Doppler

62
Q

What is auto correction?

A

Obtaining mean Doppler shift frequency

63
Q

Package size is also known as?

A

Ensamble length

64
Q

What is packet size?

A

Group of pulses
Number of pulses per color line
Compose of 3 to 20 pulses

65
Q

The larger the package size

A

Lower the frame rate

66
Q

When a packet has more pulses, the following results occur?

A

Velocity measurement more accurate
More time required to collect data from each scan line which degrades temporal resolution
More poses are needed to make a single frame

67
Q

What is hemodynamics?

A

Study of motion and the force of blood

68
Q

The human circulatory system consists of?

A 
Heart
Arteries
Arterioles
Capillaries
Venules
Veins
69
Q

How many liters of blood is in the circulatory system?

A

5 L

70
Q

What is stroke volume?

A

Volume of blood that is ejected by the left ventricle into aorta. Each heartbeat equals to 75 to 80 ml

71
Q

Blood consists of

A

Plasma 90% water 10% protein
RBC 90% cells contain hemoglobin
WBC protect body
Platelets smaller blood cell, helps in blood clotting

72
Q

What are the two important characteristics of blood?

A

Density

Viscosity

73
Q

What is density?

A

Equal to Mass per unit of volume

74
Q

What is the formula for density?

A

D=M/V

75
Q

What is viscosity?

A

Resistance to blood in motion

76
Q

Viscosities unit is

A

Poise

77
Q

Viscosity blood is about?

A

0.035 poise

78
Q

What is pulsatile flow?

A

Normal in arterial circulatory system

79
Q

what is plug flow?

A

Entrance of the vessel, blood travels at the same speed at the center or next to the blood vessel wall at distance, plug flow changes to parabolic flow

80
Q

What is laminar flow?

A

Particles are parallel to each other and the highest velocity of blood flow is in the center of the vessels slowing by the wall of vessel

81
Q

What is parabolic flow?

A

Develop in a long vessel with steady flow

It is a laminar flow with parabolic cone shape

82
Q

What is Disturbed flow?

A

Not steady flow
Occurs after bifurcation
Narrowing of the vessel stenosis or in the small vessel

83
Q

What is turbulent flow?

A

Occurs when Reynold’s number exceeds 2000

Baker’s ad vessel bifurcation or stenosis

84
Q

Blood flow occurs between differences in

A

Energy and pressure which is called gradients

85
Q

Blood pressure is higher in the legs when standing or when sitting down

A

In the legs

86
Q

What is pressure gradient?

A

blood flow to occur between any two points in the circulatory system there has to be different than the energy level pressure between the two points

87
Q

What are the two types of pressures the circulatory system consists of?

A 
High pressure (Arterial)
Low pressure (venous)
88
Q

What are the two systems that are connected by a micro circulation?

A

Capillaries

Resistance vessels

89
Q

Both pressure and energy increase or decrease when blood moves from the arterial system to the venous system

A

Decrease

90
Q

CWD measures anywhere along the length of the beam which is called?

A

Range ambiguity

91
Q

PWD selects sample called

A

Range Resolution

92
Q

CWD measures what type of velocity?

A

High velocity

Above 2.0 m/s

93
Q

PWD measures

A

Low velocity

Below 2.0 m/s

94
Q

Aliasing occurs in CWD or PWD

A

PWD

95
Q

Why can’t CWD have aliasing?

A

Cannot measure high velocity accurately. No PRF

96
Q

PWD has how many crystals?

A

1 sending and receiving

97
Q

CWD has how many crystals?

A

2 only receiving

98
Q

What is heart?

A

4 Chambers . Engine of system

99
Q

What are arteries?

A

Main conduit. Media consists of elastin

100
Q

What are arterioles?

A

Mostly muscular tissue on the wall and is responsible for 68% of the lower extremity (peripheral resistance)

101
Q

What part of the circulatory system have the highest resistance to blood flow?

A

Arterioles
Venules
Capillaries

102
Q

What are capillaries?

A

Found by only one layer of cells.

Brings nutrients and oxygen to the cells

103
Q

What is venules?

A

Take cell waste products and deoxygenated blood from

104
Q

What are veins?

A

Low resistance,
Low fow and low pressure vessels
Reservoir of the circulatory system

Practice (1 decks)

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