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SPI 1 > System Operations > Flashcards

System Operations Flashcards

1
Q

What are the 6 main components of the ultrasound system?

A 
Transducer
Pulser and beam former
Receiver
Display
Storage
Master synchronizer
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2
Q

What does the master synchronizer do?

A

It organizes and maintains the timing and interaction of the different components of the ultrasound system by use of communication

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3
Q

What does the pulser do?

A

Creates and controls electrical signals that are sent to PZT crystals to create sound beams or pulses

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4
Q

What is another term for the pulser?

A

Transmitter

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5
Q

What does the transducer do?

A

Transmission: to transform electrical energy to acoustic
Reception: to transform acoustic energy back to electrical

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6
Q

What does the receiver do?

A

Changes the electronic components from the transducer (that are created by reflected sound) and transforms them to a form suitable for display

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7
Q

What does the display do?

A

Presents the processed data from the machine

Flat screen monitor, transparency, audio speaker

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8
Q

What does the storage do?

A

Stores or archives the ultrasound studies produced by that machine
Form of hard drive, CD or DVD, videotape, USB

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9
Q

What determines the transducer output magnitude?

A

It is determined by the excitation voltage that comes from the transducer
Increased voltage means increased magnitude of PZT vibration

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10
Q

What are other terms used to describe transducer output?

A 
Output gain
Acoustic power
Pulser power
Energy output
Transmitter output
Power
Gain
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11
Q

How is the image affected when the transducer output changes?

A

When there is lower output, the entire image is darker

When there is higher output, the entire image is brighter

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12
Q

What is ultrasound “signal”?

A

The meaningful portion of the data that we want to have

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13
Q

What is ultrasound “noise”?

A

The inaccurate portion of the data that has random or persistent disturbance, reducing the signal clarity
Signal contamination

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14
Q

What is signal to noise ratio?

A

The comparison of the meaningful information to the amount of contamination

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15
Q

Is a high or low signal to noise ratio desirable?

A

High S/N ratio

This means that the signal is stronger than the noise, producing a high quality image

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16
Q

What is the primary method for improving S/N ratio?

A

Increasing output power

Improves image quality as signal dominates noise

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17
Q

What component of the US system determines the PRP (and PRF)?

A

The pulser

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18
Q

What is the beam former?

A

Transmission: creates and distributes the delay patterns for array transducers
Reception: dynamic receive focusing to establish correct time delays

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19
Q

What is adopization?

A

A process of adjustments to the electrical spike voltages to reduce lobe artifact

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20
Q

What is the receiver?

A

The electronic components of the machine that boosts the strength of the electric signals and converts them for display on the monitor?

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21
Q

What is the order of functions performed by the receiver?

A 
Amplification
Compensation
Compression
Demodulation
Reject
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22
Q

What is amplification?

A

Increases the strength of all electronic signals equally

Needed when electronic signals are too low

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23
Q

What is the synonym for receiver gain?

A

Amplification

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24
Q

How does receiver gain affect the received signals?

A

It increases the strength of all signals identically

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25
Q

How does receiver gain affect the entire image?

A

It makes the entire image brighter or darker

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26
Q

Does the receiver gain create an image of uniform brightness top to bottom?

A

No, because it affects signals equally

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27
Q

What is the preamplifier?

A

The process of improving the signal quality before it is amplified and occurs as close to the PZT as possible

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28
Q

What is the purpose of compensation?

A

To create an image with uniform brightness from top to bottom

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29
Q

What are other terms used to describe compensation?

A

Time gain compensation (TGC)
Depth compensation (DGC)
Swept gain

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30
Q

Do higher or lower frequencies require more or less compensation?

A

Higher frequencies

They attenuate more quickly and need compensation at shallower depths

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31
Q

What does compression do?

A

It reduces the total range of signals
It keeps the signals within accuracy range for system
It keeps the gray scale within human eye

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32
Q

What are other terms used to describe compression?

A

Log compression

Dynamic range

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33
Q

What is demodulation?

A

A two-part process that changes the signal to a form suitable for display
Rectification turns the negative voltages positive
Smoothing evens out the bumps by wrapping an envelope around them

34
Q

What does reject do?

A

It eliminates the low-level noise in images

Displays only meaningful low-level signals

35
Q

What signals are affected by reject?

A

All low-level echoes

No bright echoes

36
Q

What effect does reject have on an image?

A

It affects all low level echoes equally while not changing the bright echoes, causing weaker reflections to be eliminated from display

37
Q

How does output power affect the brightness of an image?

A

By altering the strength of the sound pulse that the transducer sends into the body
When the pulse is more powerful, the entire image becomes brighter

38
Q

How does receiver gain affect the brightness of an image?

A

It alters the strength of the voltages in the receiver created by the transducer during transmission
Higher amplification creates a brighter image
Lower amplification creates a darker image

39
Q

If an image is too bright should power or gain be reduced first?

A

Output power because it decreases patient exposure

ALARA

40
Q

If an image is too dark should power or gain be increased first?

A

Gain because it does not increase patient exposure

ALARA

41
Q

If you have insufficient penetration should you increase power or use a lower frequency transducer?

A

Use a lower frequency transducer because increasing power would alter patient exposure

42
Q

What is bistable?

A

Images that are only composed of black or white shades

43
Q

What is gray scale?

A

Images that are composed of many shades of gray to show multiple levels of contrast

44
Q

What is contrast?

A

The range of brilliances in the displayed image

Bistable are high contrast images

45
Q

What is brightness?

A

It determines the specific brilliance of the image

46
Q

What does the scan converter do?

A

It changes the format of stored data from spoke format to display format (horizontal lines)

47
Q

What are analog numbers?

A

Real world numbers that we use in our everyday lives
Continuous range of values
Not rounded

48
Q

What are digital numbers?

A

Numbers that are associated with computer devices
Can only have discrete values
Rounded

49
Q

What is spatial resolution?

A

Image detail

Great spatial resolution in analog scan converters

50
Q

What does the digital scan convertor do?

A

It uses the technology of the computer to convert images to numbers (digitizing)

51
Q

What is computer memory called?

A

Random Access Memory

RAM

52
Q

What is a pixel?

A

The smallest building block or element of a digital picture

Individual square boxes on the grid

53
Q

How are pixels related to spatial resolution?

A

Smaller pixels create higher pixel density, which improves spatial resolution

54
Q

What is a bit?

A

The smallest amount of digital storage of a computer’s memory

55
Q

What is a byte?

A

A group of 8 bits of computer memory

In the form of 1s and 0s

56
Q

How are the number of bits per pixel related to contrast resolution?

A

Fewer bits per pixel causes degraded contrast resolution with fewer shades of gray
More bits per pixel causes improved contrast resolution with more shades of gray

57
Q

If you know the number of bits per pixel how can you determine how many shades of gray will be presented?

A

By multiplying the number 2 times itself the same number of times as the number of bits
4 bits = 2x2x2x2 = 16 shades

58
Q

What does the analog-to-digital converter do?

A

It converts the electrical signals made by the transducer during reception from analog to digital

59
Q

What is preprocessing and when does it occur?

A

It is the processing of reflected signals that occurs before storage

60
Q

What is post-processing and when does it occur?

A

It is the processing of reflected signals that occurs after storage and in the digital scan converter

61
Q

What is read magnification and is it pre or post processing?

A

It is when the system reads the original stored image data and displays only the original data
Post processing

62
Q

What is write magnification and is it pre or post processing?

A

It is when the system rescans the area of interest and writes or provides new data to the scan converter
Preprocessing

63
Q

How does the magnification affect spatial resolution?

A

Improves spatial resolution because it has an increased number of pixels in the area of interest

64
Q

How does write magnification affect temporal resolution?

A

Improves temporal resolution when the area of interest is shallower than the original depth of view

65
Q

Where does coded excitation take place?

A

In the pulser

66
Q

What does coded excitation improve?

A

Image quality
Higher S/N
Better axial, spatial, temporal res
Deeper penetration

67
Q

What is spatial compounding?

A

When scan lines are steered by the transducer to image structures with multiple pulses from different angles

68
Q

What transducers perform spatial compounding?

A

Phased array transducers because electronic steering is necessary

69
Q

What are the benefits of spatial compounding?

A

Averages the frames by
Improving S/N ratio
Reducing speckle and clutter artifacts and shadowing

70
Q

What is frequency compounding?

A

When frequency ranges are divided into sub-bands are combined to make a single image

71
Q

What are the benefits of frequency compounding?

A

Reduces speckle artifact and noise

72
Q

What does edge enhancement do?

A

Increases the image contrast immediately around the edge of an area
Makes the image sharper with better defined boundaries

73
Q

What is temporal compounding?

A

When previous frames are superimposed over the most recent frame to create an image made of displayed information from past images

74
Q

What are synonyms for temporal compounding?

A

Persistence

Temporal averaging

75
Q

How does temporal compounding affect temporal resolution?

A

It reduces temporal resolution because it causes reduced frame rate

76
Q

What are the benefits of temporal compounding?

A

It creates a smooth image with
Higher S/N
Reduced noise
Improved image quality

77
Q

What is fill-in interpolation?

A

A method of filling in the gaps or missing data between scan lines

78
Q

Is fill-in interpolation pre or post-processing?

A

Preprocessing

79
Q

What is elastography?

A

A technique used to create an image based on the tissue’s mechanical properties

80
Q

What is dynamic range?

A

A method of describing the extent of signal variation that can occur while still maintaining accuracy

SPI 1 (13 decks)

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