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RADT 156 Equipment Operation > Digital Imaging > Flashcards

Digital Imaging Flashcards

1
Q

_____ computers handle data composed of continuous signals (current)

A

analog

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2
Q

______ computers handle data in definite quantities (discrete numbers)

A

digital

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3
Q

______ connections are a simultaneous transmission

A

parallel

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4
Q

______ connections are slower, info is transferred in a sequence

A

series

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5
Q

Specialized peripheral computer processing units
-use memory to perform simultaneous mathematical calculations in parallel (simultaneously) at high Speeds

A

array processors

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6
Q

Extracts information without alteration

A

read memory

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7
Q

Replaces old memory with new information

A

write memory

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8
Q

Read only memory, basic operating instructions

A

ROM

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9
Q

Temp storage of info during use

A

RAM

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10
Q

Primary mathematical methods used to convert data to useful information (images)

A

Fourier Transmission

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11
Q

process of modifying pixel value by masking image through math calculations- pixel masked with density value, changes image quality

A

convolution

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12
Q

process of returning pixel values to their original level by a reverse process , info returns altered image to original state

A

deconvolution

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13
Q

Pixels increase, resolution _______

A

increases

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14
Q

Digital image qualities data characteristics are measured in:

A

frequency, contrast, noise

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15
Q

raw data, the measure of the total amount of contrast within image

A

frequency

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16
Q

high frequency, ______ contrast

A

high

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17
Q

low frequency, _______ contrast

A

low

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18
Q

subject contrast is high, data contrast is ______

A

high

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19
Q

signal to noise ratio- high ratio, _____ noise

A

little

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20
Q

signal to noise ratio- low ratio, ______ noise

A

high

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21
Q

high image noise, _______ contrast

A

low

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22
Q

low image noise, ______ contrast

A

high

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23
Q

filtering process to suppress frequencies to reassign an average gray scale value to each pixel according to its neighbor’s value

A

masking

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24
Q

amplifies or deletes higher frequencies- Reduces contrast / removes high frequency noise

A

low pass filtering

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25
Q

amplifies or deletes all frequencies, but a selected range Isolates data - localization of specific densities eg.) Isotope concentration in NM

A

band pass filtering

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26
Q

amplifies or deletes all frequencies, but high frequencies- Increases contrast

A

high pass filtering

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27
Q

window level controls _____

A

density (midpoint)

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28
Q

window width controls _______

A

contrast (range of visible densities on both sides of the midpoint/ window level)

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29
Q

progressive scanning

A

increases resolution by scanning 525 lines in ORDER = 1-2lp/mm

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30
Q

slow scanning

A

raster pattern- 5-7 lp/mm

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31
Q

pixel modification- gray scale expansion does what?

A

stretches the gray scale to enhance detail

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32
Q

pixel modification- histogram modification

A

reassigns pixels to different density values to equalize the number of pixels for each gray scale

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33
Q

digital filtering- masking

A

filtering process that assigns an average gray scale value for each pixel according to it’s neighbor’s value

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34
Q

Layers of the phosphor imaging plate

A

protective layer
phosphor layer
support layer
conductor layer
light shielding layer

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35
Q

quantum motle occurs due to what

A

underexposure (high S number)

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36
Q

The phosphors of a CR imaging plate do what?

A

stores the energy of exit x-rays until processed

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37
Q

The smallest picture element with one gray scale value

A

pixel

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38
Q

A histogram of pixel values is used to (3)

A

determine the level of exposure
determine the level of brightness of pixels in the image
make adjustments in brightness levels to improve image

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39
Q

The process of subtracting an earlier image from a later image

A

temporal subtraction

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40
Q

Manipulating the gray scale values of pixels in the image is called

A

Contrast enhancement post processing

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41
Q

Window levels can be adjusted to _____ for air and ______ for bone

A

-1000, 1000

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42
Q

Image noise makes an image appear

A

grainy

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43
Q

Regarding data acquisition, as the matrix size increases, data acquisition ______

A

decreases
as the resolution increases we can acquire less data

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44
Q

Pixel with volume

A

voxel

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45
Q

Spatial Resolution: Horizontal

A

Pixels going right to left

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46
Q

Spatial Resolution: Vertical

A

Pixels going up and down

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47
Q

Ensures that all equipment speaks the same language for output devices

A

DICOM

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48
Q

Ensures that all equipment speaks the same language for input and output devices

A

DICOM2

49
Q

Digital Image display qualities are measured by (3)

A

density
contrast
resolution

50
Q

Contrast in digital imaging measures what?

A

the differences between data values

51
Q

CR imaging plate: phosphor layer

A

energizes during exposure- photostimulable phosphors

52
Q

CR imaging plate: support layer is made of what?

A

polyester

53
Q

CR Imaging plate: conductor layer

A

grounds plate to reduce static discharge- absorbs light to increase sharpness

54
Q

Smaller the pixel, _______ spatial resolution

A

greater

55
Q

Pre-Image processing: Sampling looks at what 2 factors

A

orientation to plate
number of projections on plate

56
Q

What type of sampling adjusts the latitude and sensitivity for the image and is used for multi images on one plate

A

Fuji’s Exposure Data Recognition (automatic)

57
Q

Adjusts latitude but sensitivity is fixed- image is centered but collimation is not equidistant from plate edges

A

Semi-automatic sampling

58
Q

Latitude and sensitivity are fixed, will not correct exposure deficiencies (most like film screen)

A

Fixed sampling

59
Q

X-rays are converted to electrical charge directly which is then converted to electrical pulses— then converted to an image matrix

A

DIRECT digital

60
Q

TFT used in what?

A

Direct digital

61
Q

Collects electric charge until gate is activated and signal is sent pixel by pixel

A

TFT in direct digital

62
Q

IR plate holding a charge creates what?

A

fogging

63
Q

inadequate exposure causes what?

A

quantum mottle

64
Q

IR plate exposed to heat causes what?

A

heat blur

65
Q

incorrect preprocessing selection causes what?

A

histogram error

66
Q

Advantages of digital (4)

A

Image manipulation
Image storage
Image retrieval
Transmission of images

67
Q

Disadvantages of digital

A

Patient exposure (single exposure)
Cost: Technology & Imaging Plates
Technology errors: Pre-processing selection
Decreased latitude for technical errors: Collimation & Positioning

68
Q

Range of gray scale values that can be assigned to each pixel the number of signal values that the receptor is capable of capturing.

A

dynamic range

69
Q

dynamic range of digital imaging

A

256 to 4096 shades of gray

70
Q

Selected ranges of brightness values subtracted from the image producing an image with structures at those values subtracted from the image

A

image subtraction

71
Q

Resolution of conventional film radiography

A

6-10 lp/mm

72
Q

What is a flat-panel image receptor?

A

Detector for X-rays

73
Q

How does the receptor recognize the exposure field?

A

By the number of electrons in detector element

74
Q

What does the exposure level control?

A

Number of electrons, electrical charges collected by detector element

75
Q

Why is it important to select the correct algorithm for a part?

A

Incorrect selection leads to information loss

76
Q

gradation processing

A

fuji

77
Q

tonescaling

A

Kodak

78
Q

Multiscale image contrast algorithm

A

Agfa

79
Q

graphically represent a collection of exposure values extracted from the receptor.

A

Histogram

80
Q

must quantize, or turn, that continuous stream of electrons into unique values

A

ADC

81
Q

An image is created after…

A

a histogram of the extracted image data is analyzed using one of two formats:

82
Q

the greater the number of signal values that a receptor is capable of capturing=

A

the greater the receptor’s dynamic range.

83
Q

if an image contains quantum noise is the image over or under exposed?

A

underexposed

84
Q

Modifies value of pixel to enhance or suppress a visual image characteristic

A

Convolution / Deconvolution

85
Q

Process of modifying pixel value by masking image through math calculations

A

Convolution

86
Q

Process of returning pixel values to their original level by a reverse process

A

Deconvolution

87
Q

The conversion of a radiographic image (film) post chemical processing

A

Image Digitalization

88
Q

indirect conversion- CR or DDR?

A

Computed Radiography

89
Q

Direct conversion- CR or DDR?

A

Direct digital radiography

90
Q

casette based digital image receptors:

A

PSP photostimuable storage phosphor

91
Q

Cassette-less digital image receptors:

A

-PSP photostimulable storage phosphor

-Flat Panel

-CCD (charge coupled device)

92
Q

which company invented computed radiography?

A

FUJI

93
Q

Which company uses photostimulable plates and a laser reader for their CR devices?

A

FUJI

94
Q

Which company uses silicon flat panel and TFT’s for their CR devices?

A

Phillips, GE, Siemens

95
Q

Which company use rare earth intensifying screens ans CCD’s for their CR devices?

A

SwissRay

96
Q

What is the measure of data quality?

A

Contrast, frequency, noise

97
Q

What are the qualities of a display image?

A

Brightness, contrast, resolution

98
Q

What is frequency data?

A

Raw data; measure of total amount of contrast within the image

99
Q

What is contrast?

A

Measure of differences between data values

100
Q

High subject contrast =

A

=high data contrast

101
Q

What is noise?

A

Random background information that does not contribute to image quality

102
Q

What is the relationship between noise and contrast?

A

Inverse relationship, high noise decreases contrast

103
Q

What is density/contrast?

A

Controlled by varying numerical values of each pixel

104
Q

What is the human visual range for shades of gray?

A

32 or less shades of gray

105
Q

What is the photon beam range for shades of gray?

A

1,000 shades

106
Q

What is the contrast resolution for digital detectors?

A

Sensitive to almost 1,000 shades, greater contrast resolution

107
Q

What is Window Level?

A

Density levels

108
Q

What is Window Width?

A

Contrast levels

109
Q

What are the factors to evaluate digital images?

A

Brightness, contrast, image blur, exposure indicator, image noise

110
Q

What is Image Brightness in a digital image equivalent to?

A

Opposite density in an analog image

111
Q

How is Contrast determined?

A

By the differences in adjacent densities within an image

112
Q

What is Bone Gray Scale used for?

A

To visualize bony trabeculae by manipulating the digital image characteristic of contrast

113
Q

What is Soft Tissue Gray Scale used for?

A

To enhance the difference between adjacent densities and see muscle, organs and fatty patterns better

114
Q

What causes image blur in flat panel detectors?

A

Larger DELs.

115
Q

How does increasing SID affect image blur?

A

Decreases blur.

116
Q

How does increasing OID affect image blur?

A

Increases blur.

117
Q

What are the factors that contribute to geometric unsharpness?

A

Focal spot size, SID, OID.

118
Q

An image receptor’s ability to respond to exposure

A

dynamic range

119
Q

the range of under- or overexposure that
can occur in producing an acceptable image

A

exposure latitude

RADT 156 Equipment Operation (4 decks)

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