7. Digital Imaging Characteristics Flashcards
1
Q
paintings and printed photographs
A
Analog Images
2
Q
various levels of brightness and colors
A
Analog Images
3
Q
continuous, they are not broken into their individual pieces
A
Analog Images
4
Q
infinite range of values
A
Analog Images
5
Q
Analog Images examples
A
thermometer (mercury), photocopiers, audio tapes
6
Q
recorded as multiple numeric values
A
Digital Images
7
Q
divided into an array of small elements that can be processed in many different ways
A
Digital Images
8
Q
discrete
A
Digital Images
9
Q
finite range of values
A
Digital Images
10
Q
not as exact as analog, but easier to work with
A
Digital Images
11
Q
Film based
A
Analog Images
12
Q
Produced when x-rays photons strike the film
A
Analog Images
13
Q
Shows on film as a continuous spectrum of gray shades between the extremes of white and black
A
Analog Images
14
Q
The shades “flow into” one another like a painting
A
Analog Images
15
Q
sensor is the recording medium
A
Digital Images
16
Q
produces a computerized images
A
Digital Images
17
Q
uses an array of “pixel” elements with exact gray and discrete gray values for each pixel
A
Digital Images
18
Q
more like a mosaic patterns instead of the shades “flowing together”
A
Digital Images
19
Q
Storage: lots of physical space, required, along with time and energy required to store hard copies
A
Analog Images
20
Q
Storage: higher likelihood of getting lost
A
Analog Images
21
Q
Distribution: hard copy is available only at one location
A
Analog Images
22
Q
Distribution: unless copies of image are made, healthcare professionals must travel or have image delivered
A
Analog Images
23
Q
Viewing: hard copy is limited by its size, can only be viewed by small audiences
A
Analog Images
24
Q
Lifespan: screen-film image quality degrades over time
A
Analog Images
25
Cost: screens and chemicals are less costly in isolation however repetitive purchase is more expensive in the long-run
Analog Images
26
Storage: although files are large, storage takes less time, energy and no physical space
Digital Images
27
Storage: less likely to get lost as file can be backed up
Digital Images
28
Distribution: soft copy is available on PACS, universal distributer of medical images
Digital Images
29
Distribution: any healthcare professional at any location can access the file
Digital Images
30
Distribution: easy to send image digitally
Digital Images
31
Viewing: soft copy can easily be viewed by large audiences
Digital Images
32
Lifespan: image quality does not degrade over time
Digital Images
33
Cost: expensive to purchase equipment at first (high resolution monitors etc.) however cost-effective in the long-run
Digital Images
34
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 _____
electrical impulse,
| light photon
35
refers to a device or system that captures or measures a continuously changing signal
Analog
36
is recorded or used in its original form
analog signal wave
37
is transformed into a series of pulses that corresponds to patterns of binary digits (0s, 1s)
digital signal
38
digital image begins as an _____
analog signal
39
through computer data processing, the image becomes _____ and is sampled multiples times
digitized
40
The critical characteristics of a digital image are:
- Spatial Resolution
- Contrast Resolution
- Noise
- Dose efficiency (of the receptor);
41
picture element
pixel
42
smallest element in a digital image
pixel
43
the size of the pixel is _____ related to the amount of spatial resolution or detail in the image
directly
44
the smaller the pixel is, the ____ the detail
greater
45
may change when the size of the matrix or the FOV changes
Pixel size
46
each ____ contains pieces or bits of information
pixel
47
the number of bits within a pixel is known as
pixel bit depth
48
each box within the ____ also corresponds to a specific location in the image and corresponds to a specific area of the patient's tissue
matrix
49
the image digitized both by
position (spatial location) and intensity (gray level)
50
Matrix sizes
512 x 512
1024 x 1024
2500 x 2500
51
square arrangement of numbers in columns and rows
Matrix
52
in digital imaging, the numbers correspond to discrete pixel values
Matrix
53
the size of the _____ determines the size of the pixels
matrix
54
synonymous with the x-ray field
Field of View
55
the amount of body part or patient included in the image
Field of View
56
the larger the FOV, the ____ area is imaged
more
57
changes in the ____, will not affect the size of the matrix; however, changes in the matrix will affect pixel size
FOV
58
Same FOV, increase matrix, _____ pixel
decrease
59
a relationship may exist between the ___ of the pixel, the size of the matrix, and the FOV
size
60
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
changes
61
refers to the amount of exposure received by the image receptor (IR), not by the patient
Exposure index
62
used to indicate the relative speed and sensitivity of the digital receptor to incident x-rays
Exposure index
63
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
Exposure index
64
Standard Units of Measure
- Air Kerma
- Standardized Radiation Exposure (KSTD)
- Indicated Equivalent Air Kerma (KIND)
- Target Equivalent Air Kerma Value (KTGT)
- Deviation Index
65
kinetic energy released per unit mass (of air) the measurement of radiation energy (joules or J) absorbed in unit of air (kg)
Air Kerma (J/kg or Gray)
66
standard exposure typical of that imaging receptor system
Standardized Radiation Exposure (KSTD)
67
exposure is made with additional filtration that hardens the beam to stimulate patient tissue
Standardized Radiation Exposure (KSTD)
68
used to ensure that the equipment is function properly
Standardized Radiation Exposure (KSTD)
69
measurement of the radiation that was incident on the IR for that particular exposure
Indicated Equivalent Air Kerma (KIND)
70
amount of exposure to the IR
Indicated Equivalent Air Kerma (KIND)
71
this value will help determine whether the IR has been overexposed or underexposed for the particular body part
Indicated Equivalent Air Kerma (KIND)
72
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
Target Equivalent Air Kerma Value (KTGT)
73
for example, there will be established perfect exposures for a PA chest, lateral chest, portable chest, pediatric chest and so on
Target Equivalent Air Kerma Value (KTGT)
74
the difference between the actual exposure (KIND) and the target exposure (KTGT)
Deviation Index
75
intended to help the technologist determine whether the image has been underexposed or overexposed
Deviation Index
76
can be used to adjust technical factors if the image must be repeated
Deviation Index
77
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
Brightness
78
terms to use for the measurement of brightness using a photometer
Luminance
79
ability of the digital system to display subtle changes in the shade of gray
Contrast Resolution
80
the differences between adjacent densities are enhances
Higher Contrast Resolution
81
more shades of gray may be demonstrated resulting in the ability to demonstrate between small differences in densities
Higher Contrast Resolution
82
directly related to bit depth of pixels in the image
Contrast Resolution
83
the ability of the imaging system to demonstrate small details of an object
Spatial Resolution
84
crystal size and thickness of the phosphor layer
Film-screen radiography
85
phosphor layer thickness and pixel size
Photostimulable Phosphors
86
pixel size and capture technique
Active Matrix Flat Panel Images
87
thinner phosphor layers and smaller pixels produces images with ____ resolution
higher
88
PSP pixel
200 micrometer
89
Gd AMFPI pixel
150 micrometer
90
Cs AMFPI pixel
125 to 100 micrometer
91
A-Se pixel
50 micrometer
92
the ability to respond to varying levels of exposure
Dynamic Range
93
more tissues densities on the digital image are seen, giving the appearance of more detail
Dynamic Range
94
The smaller the pixels, the _____ the spatial resolution
higher
95
describes the range of x-ray intensities a detector can differentiate
Dynamic Range
96
ability of the combine components of a system to accurately reproduce the structural details of an object within the image
Modulation Transfer Function
97
a way to quantify the contribution of each system component to the overall efficiency of the entire system
Modulation Transfer Function
98
is a ratio of the image to the object
Modulation Transfer Function
99
a perfect system would have an MTF of
1% or 100%
100
both in film-screen and digital imaging, anything that interferes with the formation of the image
Noise
101
superimposition of body parts
Anatomic Noise
102
occurs during image requisition
Radiographic Noise (Quantum/Equipment Noise)
103
refers to the range of exposure a digital detector can respond to
Exposure Latitude
104
o Range of exposure values (diagnostic image) the image detector is able to produce
Exposure Latitude
105
o Dependent on the image detector, the higher the dynamic range, the more values can be detected
Exposure Latitude
106
How efficient a system converts the X-ray input signal into a useful output image
Detective Quantum Efficiency
107
Measurement of the percentage of X-rays that is absorbed when they hit the detector
Detective Quantum Efficiency
108
System with higher quantum efficiency can produce ____-quality images at ___ doses
higher,
| low
109
______ detector technology have increased DQE over PSP
A-Se, A-Si, TFT,CCD and CMOS
110
has the highest DQE since they do not have light conversions, there’s no light spread
A-Se
