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Ultrasound Physics > Exam 4 Flashcards > Flashcards

Exam 4 Flashcards

1
Q

Ability to detect and display echo amplitude differences

A

Contrast resolution

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2
Q

Better contrast resolution allows for differentiation of echoes that are

A

Very close together in amplitude to be shown as different SOG

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3
Q

What is the gold standard for resolution

A

Ability to display fetal lip echoes at different SOG than fetal cheek echo

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4
Q

What is the equation of contrast resolution

A

Dynamic range/SOG

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5
Q

What are the units of contract resolution

A

dB/SOG

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6
Q

Contrast resolution is determined by

A

Dynamic range and number of SOG it can store/display

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7
Q

When echoes are further apart in amplitude and intensity they’re displayed as

A

Different shades

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8
Q

Poor resolution echoes are ____ (Far or close) and are the same _____

A

Close and are same SOG

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9
Q

Range of signals that a piece of equipment is processing

A

Dynamic Range

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10
Q

The minimum dynamic range is detected by

A

Piece of equipment

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11
Q

The maximum dynamic range can be

A

Processed without distoration

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12
Q

What are the units of dynamic range

A

dB

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13
Q

What is the equation for Nyquist criteria

A

PRF/2

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14
Q

Analog numbers have _____ & _____ values

A

Unlimited and continuous

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15
Q

What was the first type of scan converter

A

Analog

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16
Q

Analog converted has good spatial resolution because of

A

Continous values being read and displayed

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17
Q

What are the disadvantages of analog scan converter

A

Instability
Image flicker
Deterioration
Image fade

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18
Q

What causes the instability in analog scan converter

A

Image is influenced by other factors such as room temp

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19
Q

What causes the image flicker in analog scan converter

A

Constant need to read and write new info

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20
Q

What causes the deterioration in analog scan converter

A

The older the image the more the image degrades

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21
Q

What causes the image fade in analog scan converter

A

Electron charges dissipated and image becomes darker over time

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22
Q

Digital numbers have _____ & _____ values

A

Distinct & Discrete Values

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23
Q

T or F:
Digital numbers sample and store only some values

A

True

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24
Q

What are the advantages of digital scan converter

A

Durability
Uniformity
Stability
Accuracy

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25
Q

What causes the durability for the digital scan converter

A

Quality of image doesn’t deteriorate with age/heavy use

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26
Q

What causes the uniformity for the digital scan converter

A

Image has consistent grayscale throughout

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27
Q

What causes the stability for the digital scan converter

A

Image doesn’t fade or drift

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28
Q

What causes the accuracy for the digital scan converter

A

Image is error free

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29
Q

T or F:
Convert D to A first

A

False
Convert A to D

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30
Q

Smallest part of digital picture that can be controlled

A

Pixel

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31
Q

Pixel is denisty per

A

Inch

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32
Q

High pixel density improves ____ ____ and results in an image with _____ (Good or poor) detail

A

Spatial resolution, better detail

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33
Q

How many bits are in 1 byte

A

8

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34
Q

Magnification is used to

A

Improve visualization f ROI

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35
Q

Performed while data is being read in, before storage in the scan converter

A

Write magnification

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36
Q

What are the 4 steps for write magnification

A

Scan
Convert A to D
Identify ROI & system discards data
U/S system rescans ROI & write new data

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37
Q

Finish the characteristics of write magnification:
Used to -
Number of pixels in ROI -
Increased number of pixels in -

A

Identify ROI discarded
Greater than ROI of original image
ROI improves spatial resolution

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38
Q

Performed after image is stored in scan converter

A

Read magnification

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39
Q

What are the 3 steps for read magnification

A

Scan
Convert A to D, store data
Select ROI, system reads & displays only that info

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40
Q

Finish the characteristics of read magnification:
Number of pixels in magnified image -
Spatial resolution -
Can be done -

A

Same as in original
Does not change
On frozen image

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41
Q

What is Bernoulli’s equation

A

P + 1/2pv^2 + pgh

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42
Q

What does P stand for in Bernoulli’s equation and what are it’s units

A

Pressure
Pascals

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43
Q

What does p stand for in Bernoulli’s equation and what is the equation for it

A

Density
Mass/volume

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44
Q

What does v stand for in Bernoulli’s equation

A

Velocity

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45
Q

What does 1/2pv^2 stand for in Bernoulli’s equation

A

Kinetic energy

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46
Q

What does pgh stand for and when is it cut out

A

Potential energy
Cut out in stenosis

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47
Q

What does capacitance look at

A

Change in volume

48
Q

What is the equation for capacitance

A

Change in volume/Change in time

49
Q

What is the equation for compliance

A

Change in volume/Change in pressure

50
Q

The greek letter n or ____ is used to represent _____

A

Aeta
Viscosity

51
Q

Define viscosity

A

Resistence to flow

52
Q

What is the resistance expression

A

R = 8nl/pie x r^4

53
Q

What is RN

A

Reynolds number

54
Q

What does the Reynolds number 2,000 or 3,000 indicate

A

Turbulence

55
Q

In a series you will have a larger

56
Q

In parallel you will always have a smaller

57
Q

Is pressure higher in your legs than in your arm?

58
Q

CRT stands for
Also known as

A

Cathode Ray Tube
Electron gun

59
Q

CRT’s important component is the

A

Anode/focusing coil

60
Q

What do focusing coils do

A

Eliminate stray electrons

61
Q

Sweeping coils are ____ that do what to the electron beam

A

Magents that move electron beam to different regions across the screen

62
Q

Draw the CRT diagram

A

Electron gun
Focusing coil
Sweeping coil
Electron beam
Phosphorus

63
Q

RGB used to produce

A

All colors of rainbow

64
Q

Substance that glows when activated by electron gun

A

Phosphorus

65
Q

Define rastering

A

Sweeping of the beam across the display

66
Q

What are the 4 characteristics of imaging

A

Normal incidence
High f improves resolution
PW only
Min 1 crystal

67
Q

What are the characteristics of Doppler

A

0-180
Low f, avoid aliasing
PW & CW
Min of 1 for PW, 2 for CW

68
Q

What does BART represent

A

Blue away, red towards

69
Q

CW has the ____ (Highest or Lowest) velocity anywhere along ____ of beam

A

Highest
Length

70
Q

What are the 4 characteristics of CW Doppler:
R
M
G
N

A

Range ambiguity
Most sensitive
Good temporal resolution
No aliasing

71
Q

Why does CW Doppler have 2 elements

A

Transmitting always busy so necessary to have one for receiving

72
Q

CW Doppler is produced by continuous application of

A

Alternating electrical current

73
Q

CW Doppler is determined by

A

Frequency of alternating current

74
Q

CW alternates current by

A

Flipping positive and negative charge

75
Q

PW Doppler is good on

A

Location of flow

76
Q

What are 4 characteristics of PW Doppler:
R
M
G
A

A

Range resolution
Moderate sensitivity
Good temporal resolution
Aliasing

77
Q

What do CW and PW Doppler measure

A

Peak velocity

78
Q

What is on the X-Axis and Y-Axis for PW Doppler

A

X-Axis - Time
Y-Axis - Frequency/Velocity

79
Q

PW is produced by short

A

Repeated pulses with pauses between

80
Q

Where are the positive and negative shifts shown on PW Doppler

A

Positive is above baseline
Negative is below baseline

81
Q

What are the 3 ways of increasing aliasing

A

Faster blood flow velocity
High f transducer
Deeper gates/Low PRF

82
Q

What are the 5 ways to clean up aliasing

A

Adjust max scale
Select new window with shallow simple volume
Use low f transducer
Use baseline shift
Use CW Doppler

83
Q

How does adjusting max scale affect Nyquist limit

84
Q

How does selecting a new window with shallow simple volume affect Nyquist limit

85
Q

How does using low f transducer affect Doppler shift

86
Q

How does using baseline shift affect display

A

Display looks better

87
Q

Using CW Doppler may avoid ____ but then you deal with ____ ____

A

Aliasing
Range ambiguity

88
Q

With deep Doppler smaple gate and high velocity flow operator must choose between

A

Aliasing and range ambiguity

89
Q

Deep ultrasound reflectors requires ____ (Long or Short) PRP and ____ (High or Low) PRF

90
Q

High velocity blood has high Doppler shifts requires ____ (high or low) PRF to avoid ____

A

High PRF
Avoid aliasing

91
Q

Info from number of pulses required to estimate velocity of blood flow

A

Pulse packet

92
Q

I iii I iii I
The i’s represent

A

Echoes going and returning

93
Q

Which return first shallow or deep

94
Q

The heart has __mm of mercury

95
Q

What is the equation of continuity

A

Q = avg velocity x area

96
Q

If you have a narrow region how does that affect your velocity

A

Faster velocity

97
Q

If you have high velocity you will have a ____ (Small or big) area

98
Q

What are the 4 devices used for storage

A

Paper
Magnetic Media
Chemical Derived Photos
Optical media

99
Q

What are the 5 order of receiver operations

A

Amplitfication
Compensation
Compression
Demodulation
Reject

100
Q

What is the equation for parallel series

A

1/Reffective = 1/R1 + 1/R2

101
Q

What does amplification do

A

Each signal returning from trip is larger

102
Q

What does compensation do

A

Correct for attenuation

103
Q

What does compression do

A

Keeps grayscale in content in regions of viewable shades

104
Q

What does demodulation do

A

Electrical signal from receiver is made into suitable image

105
Q

What does reject do

A

Suppresses spurious signals

106
Q

How much is 1 byte of info

107
Q

If you increase your length how will that affect your resistence

108
Q

If you decrease your viscosity how will that affect your resistance

109
Q

If your radius decreases how will that affect your resistance

A

Increase (To the 4th power)

110
Q

If you radius is decrease of 1/16 then your resistence will be

A

Increase by 16

111
Q

Blood flow is due to change in

112
Q

In CRT which do you sweep first, odds or evens?

113
Q

If you have 0 compliance what will it do

A

Not change anything

114
Q

Finite can increase

115
Q

T or F:
Infinite does exist

A

False
Doesn’t exist

116
Q

What is the Hemo Law Equation

A

Change in pressure = Q (fluid flow) x Resistance

117
Q

If you have a fixed change in pressure and your fluid flow (Q) is increased how will that affect your resistance

Ultrasound Physics (6 decks)

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