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Ultrasound Physics > 14 Displays > Flashcards

14 Displays Flashcards

1
Q

What are characteristics of a bistable display?

A 
2 choices - black or white
On or off
High contrast
Narrow dynamic range
Poor contrast resolution
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2
Q

What are characteristics of a gray scale display?

A 
Many shades of gray
Multiple levels
Low contrast
Wide dynamic range
Good contrast resolution
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3
Q

What are the controls of the display?

A

Brightness - brilliance of image

Contrast - range of brilliancies that are displayed

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4
Q

What is analog?

A

Real world - variable attains a continuum of values

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5
Q

What is digital?

A

Computer world - variable attains only discrete values

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6
Q

What are scan converters?

A

Changes data format from penetrations (spokes) to horizontal lines of a display

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7
Q

What is a pixel?

A

Smallest element of a digital picture

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8
Q

What is pixel density?

A

Pixels per inch - more pixels = more detail, spatial or detail resolution

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9
Q

What determines spatial resolution on a digital display?

A

Pixel density

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10
Q

What is spatial resolution related to?

A

Number of lines per frame

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11
Q

What is a binary digit (bit)?

A

Smallest amount of digital storage

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12
Q

What is better with more bits per pixel?

A

Contrast resolution

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13
Q

What is a binary number?

A

Group of bits

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14
Q

What is a byte?

A

Group of 8 bits

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15
Q

What is a word?

A

2 bytes (16 bits)

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16
Q

How do you calculate the number of gray shades that a collection of bits can represent?

A
  1. Find out how many bits are assigned to each pixel
  2. Multiply the # 2 by itself the same # of times as there are bits
    2^n, n = # of bits
17
Q

What is image preprocessing?

A 
Manipulating the data before storage in the scan converter and cannot be reversed
TGC
Log compression
Write magnification
Fill-in interpolation
Persistence (frame averaging)
Spatial compounding
18
Q

What is log compression?

A

Ability of humans to see gray scale differences in anatomic structures - lowers high level echoes and boosts low level echoes

19
Q

What is image postprocessing?

A

Manipulating data after it has been stored in the scan converter memory but prior to display
Read magnification
3-D rendering

20
Q

What type of images is postprocessing used?

A

Frozen images

21
Q

What is an analog-to-digital converter?

A

Analog signal (electrical signals by the PZT) converted into digital form for input into the scan converter

22
Q

What is digital-to-analog conversion?

A

Conversion of info in scan converter to analog form to display

23
Q

Describe flow of information through an ultrasound system.

A 
Master Synchronizer >
Pulser >
Beam Former (beam steering) >
Transducer >
Receiver (preprocessing) >
Scan Converter (A to D > Digital data > D to A) >
Display >
Image Archive

Ultrasound Physics (20 decks)

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