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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
How does receiver gain affect the entire image?
It makes the entire image brighter or darker
26
Does the receiver gain create an image of uniform brightness top to bottom?
No, because it affects signals equally
27
What is the preamplifier?
The process of improving the signal quality before it is amplified and occurs as close to the PZT as possible
28
What is the purpose of compensation?
To create an image with uniform brightness from top to bottom
29
What are other terms used to describe compensation?
Time gain compensation (TGC) Depth compensation (DGC) Swept gain
30
Do higher or lower frequencies require more or less compensation?
Higher frequencies | They attenuate more quickly and need compensation at shallower depths
31
What does compression do?
It reduces the total range of signals It keeps the signals within accuracy range for system It keeps the gray scale within human eye
32
What are other terms used to describe compression?
Log compression | Dynamic range
33
What is demodulation?
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
What does reject do?
It eliminates the low-level noise in images | Displays only meaningful low-level signals
35
What signals are affected by reject?
All low-level echoes | No bright echoes
36
What effect does reject have on an image?
It affects all low level echoes equally while not changing the bright echoes, causing weaker reflections to be eliminated from display
37
How does output power affect the brightness of an image?
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
How does receiver gain affect the brightness of an image?
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
If an image is too bright should power or gain be reduced first?
Output power because it decreases patient exposure | ALARA
40
If an image is too dark should power or gain be increased first?
Gain because it does not increase patient exposure | ALARA
41
If you have insufficient penetration should you increase power or use a lower frequency transducer?
Use a lower frequency transducer because increasing power would alter patient exposure
42
What is bistable?
Images that are only composed of black or white shades
43
What is gray scale?
Images that are composed of many shades of gray to show multiple levels of contrast
44
What is contrast?
The range of brilliances in the displayed image | Bistable are high contrast images
45
What is brightness?
It determines the specific brilliance of the image
46
What does the scan converter do?
It changes the format of stored data from spoke format to display format (horizontal lines)
47
What are analog numbers?
Real world numbers that we use in our everyday lives Continuous range of values Not rounded
48
What are digital numbers?
Numbers that are associated with computer devices Can only have discrete values Rounded
49
What is spatial resolution?
Image detail | Great spatial resolution in analog scan converters
50
What does the digital scan convertor do?
It uses the technology of the computer to convert images to numbers (digitizing)
51
What is computer memory called?
Random Access Memory | RAM
52
What is a pixel?
The smallest building block or element of a digital picture | Individual square boxes on the grid
53
How are pixels related to spatial resolution?
Smaller pixels create higher pixel density, which improves spatial resolution
54
What is a bit?
The smallest amount of digital storage of a computer's memory
55
What is a byte?
A group of 8 bits of computer memory | In the form of 1s and 0s
56
How are the number of bits per pixel related to contrast resolution?
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
If you know the number of bits per pixel how can you determine how many shades of gray will be presented?
By multiplying the number 2 times itself the same number of times as the number of bits 4 bits = 2x2x2x2 = 16 shades
58
What does the analog-to-digital converter do?
It converts the electrical signals made by the transducer during reception from analog to digital
59
What is preprocessing and when does it occur?
It is the processing of reflected signals that occurs before storage
60
What is post-processing and when does it occur?
It is the processing of reflected signals that occurs after storage and in the digital scan converter
61
What is read magnification and is it pre or post processing?
It is when the system reads the original stored image data and displays only the original data Post processing
62
What is write magnification and is it pre or post processing?
It is when the system rescans the area of interest and writes or provides new data to the scan converter Preprocessing
63
How does the magnification affect spatial resolution?
Improves spatial resolution because it has an increased number of pixels in the area of interest
64
How does write magnification affect temporal resolution?
Improves temporal resolution when the area of interest is shallower than the original depth of view
65
Where does coded excitation take place?
In the pulser
66
What does coded excitation improve?
Image quality Higher S/N Better axial, spatial, temporal res Deeper penetration
67
What is spatial compounding?
When scan lines are steered by the transducer to image structures with multiple pulses from different angles
68
What transducers perform spatial compounding?
Phased array transducers because electronic steering is necessary
69
What are the benefits of spatial compounding?
Averages the frames by Improving S/N ratio Reducing speckle and clutter artifacts and shadowing
70
What is frequency compounding?
When frequency ranges are divided into sub-bands are combined to make a single image
71
What are the benefits of frequency compounding?
Reduces speckle artifact and noise
72
What does edge enhancement do?
Increases the image contrast immediately around the edge of an area Makes the image sharper with better defined boundaries
73
What is temporal compounding?
When previous frames are superimposed over the most recent frame to create an image made of displayed information from past images
74
What are synonyms for temporal compounding?
Persistence | Temporal averaging
75
How does temporal compounding affect temporal resolution?
It reduces temporal resolution because it causes reduced frame rate
76
What are the benefits of temporal compounding?
It creates a smooth image with Higher S/N Reduced noise Improved image quality
77
What is fill-in interpolation?
A method of filling in the gaps or missing data between scan lines
78
Is fill-in interpolation pre or post-processing?
Preprocessing
79
What is elastography?
A technique used to create an image based on the tissue's mechanical properties
80
What is dynamic range?
A method of describing the extent of signal variation that can occur while still maintaining accuracy

SPI 1 (13 decks)

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