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RT 212 > 7. Digital Imaging Characteristics > Flashcards

7. Digital Imaging Characteristics Flashcards

1
Q

paintings and printed photographs

A

Analog Images

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2
Q

various levels of brightness and colors

A

Analog Images

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3
Q

continuous, they are not broken into their individual pieces

A

Analog Images

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4
Q

infinite range of values

A

Analog Images

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5
Q

Analog Images examples

A

thermometer (mercury), photocopiers, audio tapes

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6
Q

recorded as multiple numeric values

A

Digital Images

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7
Q

divided into an array of small elements that can be processed in many different ways

A

Digital Images

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8
Q

discrete

A

Digital Images

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9
Q

finite range of values

A

Digital Images

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10
Q

not as exact as analog, but easier to work with

A

Digital Images

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11
Q

Film based

A

Analog Images

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12
Q

Produced when x-rays photons strike the film

A

Analog Images

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13
Q

Shows on film as a continuous spectrum of gray shades between the extremes of white and black

A

Analog Images

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14
Q

The shades “flow into” one another like a painting

A

Analog Images

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15
Q

sensor is the recording medium

A

Digital Images

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16
Q

produces a computerized images

A

Digital Images

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17
Q

uses an array of “pixel” elements with exact gray and discrete gray values for each pixel

A

Digital Images

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18
Q

more like a mosaic patterns instead of the shades “flowing together”

A

Digital Images

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19
Q

Storage: lots of physical space, required, along with time and energy required to store hard copies

A

Analog Images

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20
Q

Storage: higher likelihood of getting lost

A

Analog Images

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21
Q

Distribution: hard copy is available only at one location

A

Analog Images

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22
Q

Distribution: unless copies of image are made, healthcare professionals must travel or have image delivered

A

Analog Images

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23
Q

Viewing: hard copy is limited by its size, can only be viewed by small audiences

A

Analog Images

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24
Q

Lifespan: screen-film image quality degrades over time

A

Analog Images

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25
Q

Cost: screens and chemicals are less costly in isolation however repetitive purchase is more expensive in the long-run

A

Analog Images

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26
Q

Storage: although files are large, storage takes less time, energy and no physical space

A

Digital Images

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27
Q

Storage: less likely to get lost as file can be backed up

A

Digital Images

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28
Q

Distribution: soft copy is available on PACS, universal distributer of medical images

A

Digital Images

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29
Q

Distribution: any healthcare professional at any location can access the file

A

Digital Images

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30
Q

Distribution: easy to send image digitally

A

Digital Images

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31
Q

Viewing: soft copy can easily be viewed by large audiences

A

Digital Images

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32
Q

Lifespan: image quality does not degrade over time

A

Digital Images

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33
Q

Cost: expensive to purchase equipment at first (high resolution monitors etc.) however cost-effective in the long-run

A

Digital Images

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34
Q

When we talk about digitizing a signal from a digital radiographic unit, we are talking about assigning a numerical value to each signal point, either an ______ or a _____

A

electrical impulse,

light photon

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35
Q

refers to a device or system that captures or measures a continuously changing signal

A

Analog

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36
Q

is recorded or used in its original form

A

analog signal wave

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37
Q

is transformed into a series of pulses that corresponds to patterns of binary digits (0s, 1s)

A

digital signal

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38
Q

digital image begins as an _____

A

analog signal

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39
Q

through computer data processing, the image becomes _____ and is sampled multiples times

A

digitized

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40
Q

The critical characteristics of a digital image are:

A
  • Spatial Resolution
  • Contrast Resolution
  • Noise
  • Dose efficiency (of the receptor);
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41
Q

picture element

A

pixel

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42
Q

smallest element in a digital image

A

pixel

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43
Q

the size of the pixel is _____ related to the amount of spatial resolution or detail in the image

A

directly

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44
Q

the smaller the pixel is, the ____ the detail

A

greater

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45
Q

may change when the size of the matrix or the FOV changes

A

Pixel size

46
Q

each ____ contains pieces or bits of information

A

pixel

47
Q

the number of bits within a pixel is known as

A

pixel bit depth

48
Q

each box within the ____ also corresponds to a specific location in the image and corresponds to a specific area of the patient’s tissue

A

matrix

49
Q

the image digitized both by

A

position (spatial location) and intensity (gray level)

50
Q

Matrix sizes

A

512 x 512
1024 x 1024
2500 x 2500

51
Q

square arrangement of numbers in columns and rows

A

Matrix

52
Q

in digital imaging, the numbers correspond to discrete pixel values

A

Matrix

53
Q

the size of the _____ determines the size of the pixels

A

matrix

54
Q

synonymous with the x-ray field

A

Field of View

55
Q

the amount of body part or patient included in the image

A

Field of View

56
Q

the larger the FOV, the ____ area is imaged

A

more

57
Q

changes in the ____, will not affect the size of the matrix; however, changes in the matrix will affect pixel size

A

FOV

58
Q

Same FOV, increase matrix, _____ pixel

A

decrease

59
Q

a relationship may exist between the ___ of the pixel, the size of the matrix, and the FOV

A

size

60
Q

matrix size can be changed without affecting the FOV and the FOV can be changed without affecting the matrix size, but a change in either the matrix size and/or the FOV _____ the size of the pixels

A

changes

61
Q

refers to the amount of exposure received by the image receptor (IR), not by the patient

A

Exposure index

62
Q

used to indicate the relative speed and sensitivity of the digital receptor to incident x-rays

A

Exposure index

63
Q

to provide feedback to the technologist regarding the proper radiographic techniques for a specific exam that achieves an optimal image in terms of appropriate quality and corresponding low dose to the patient

A

Exposure index

64
Q

Standard Units of Measure

A
  • Air Kerma
  • Standardized Radiation Exposure (KSTD)
  • Indicated Equivalent Air Kerma (KIND)
  • Target Equivalent Air Kerma Value (KTGT)
  • Deviation Index
65
Q

kinetic energy released per unit mass (of air) the measurement of radiation energy (joules or J) absorbed in unit of air (kg)

A

Air Kerma (J/kg or Gray)

66
Q

standard exposure typical of that imaging receptor system

A

Standardized Radiation Exposure (KSTD)

67
Q

exposure is made with additional filtration that hardens the beam to stimulate patient tissue

A

Standardized Radiation Exposure (KSTD)

68
Q

used to ensure that the equipment is function properly

A

Standardized Radiation Exposure (KSTD)

69
Q

measurement of the radiation that was incident on the IR for that particular exposure

A

Indicated Equivalent Air Kerma (KIND)

70
Q

amount of exposure to the IR

A

Indicated Equivalent Air Kerma (KIND)

71
Q

this value will help determine whether the IR has been overexposed or underexposed for the particular body part

A

Indicated Equivalent Air Kerma (KIND)

72
Q

a set values, established by either the system manufacturer or the system user, the represents an optimal exposure for each specific body part and view

A

Target Equivalent Air Kerma Value (KTGT)

73
Q

for example, there will be established perfect exposures for a PA chest, lateral chest, portable chest, pediatric chest and so on

A

Target Equivalent Air Kerma Value (KTGT)

74
Q

the difference between the actual exposure (KIND) and the target exposure (KTGT)

A

Deviation Index

75
Q

intended to help the technologist determine whether the image has been underexposed or overexposed

A

Deviation Index

76
Q

can be used to adjust technical factors if the image must be repeated

A

Deviation Index

77
Q

appearance on the display monitor of the computer and is a function of the monitor’s ability to emit light through the surface of the display

A

Brightness

78
Q

terms to use for the measurement of brightness using a photometer

A

Luminance

79
Q

ability of the digital system to display subtle changes in the shade of gray

A

Contrast Resolution

80
Q

the differences between adjacent densities are enhances

A

Higher Contrast Resolution

81
Q

more shades of gray may be demonstrated resulting in the ability to demonstrate between small differences in densities

A

Higher Contrast Resolution

82
Q

directly related to bit depth of pixels in the image

A

Contrast Resolution

83
Q

the ability of the imaging system to demonstrate small details of an object

A

Spatial Resolution

84
Q

crystal size and thickness of the phosphor layer

A

Film-screen radiography

85
Q

phosphor layer thickness and pixel size

A

Photostimulable Phosphors

86
Q

pixel size and capture technique

A

Active Matrix Flat Panel Images

87
Q

thinner phosphor layers and smaller pixels produces images with ____ resolution

A

higher

88
Q

PSP pixel

A

200 micrometer

89
Q

Gd AMFPI pixel

A

150 micrometer

90
Q

Cs AMFPI pixel

A

125 to 100 micrometer

91
Q

A-Se pixel

A

50 micrometer

92
Q

the ability to respond to varying levels of exposure

A

Dynamic Range

93
Q

more tissues densities on the digital image are seen, giving the appearance of more detail

A

Dynamic Range

94
Q

The smaller the pixels, the _____ the spatial resolution

A

higher

95
Q

describes the range of x-ray intensities a detector can differentiate

A

Dynamic Range

96
Q

ability of the combine components of a system to accurately reproduce the structural details of an object within the image

A

Modulation Transfer Function

97
Q

a way to quantify the contribution of each system component to the overall efficiency of the entire system

A

Modulation Transfer Function

98
Q

is a ratio of the image to the object

A

Modulation Transfer Function

99
Q

a perfect system would have an MTF of

A

1% or 100%

100
Q

both in film-screen and digital imaging, anything that interferes with the formation of the image

A

Noise

101
Q

superimposition of body parts

A

Anatomic Noise

102
Q

occurs during image requisition

A

Radiographic Noise (Quantum/Equipment Noise)

103
Q

refers to the range of exposure a digital detector can respond to

A

Exposure Latitude

104
Q

o Range of exposure values (diagnostic image) the image detector is able to produce

A

Exposure Latitude

105
Q

o Dependent on the image detector, the higher the dynamic range, the more values can be detected

A

Exposure Latitude

106
Q

How efficient a system converts the X-ray input signal into a useful output image

A

Detective Quantum Efficiency

107
Q

Measurement of the percentage of X-rays that is absorbed when they hit the detector

A

Detective Quantum Efficiency

108
Q

System with higher quantum efficiency can produce ____-quality images at ___ doses

A

higher,

low

109
Q

______ detector technology have increased DQE over PSP

A

A-Se, A-Si, TFT,CCD and CMOS

110
Q

has the highest DQE since they do not have light conversions, there’s no light spread

A

A-Se

RT 212 (10 decks)

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