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Exposures II > Ch.20 > Flashcards

Ch.20 Flashcards

1
Q

Two types of digital radiography systems

A

CR and DR

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2
Q

This type of digital radiography deals with photostimuable imaging plates (PSP, IP)

A

CR

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3
Q

Referred to as flat panel detectors (panels)

A

DR receptors

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4
Q

This type of digital radiography deals with direct conversion without scintillator and indirect conversion with scintillator

A

DR

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5
Q

What type of digital radiography system does healthcare reimbursements encourage?

A

DR

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6
Q

When were the most changes made as far as historical development?

A

1970s and 1990s
-digital computerization of CT, ultrasound, MRI, Mammo

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7
Q

Requires binary machine language

A

two symbol alphabet
(0 and 1)

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8
Q

Bit versus byte

A

8 bits=1 byte

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9
Q

Digital image formation must be converted to digital language

A

Analog-to- digital conversion

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10
Q

ADC involves two distinct steps

A

Sampling and qualification

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11
Q

Computer memory and power expressed in total bytes

A

-megabytes, gigabytes, terabyes

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12
Q

Digital data consists of bit values

A

Binary digit

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13
Q

Bit strings connected as:

A

Bytes

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14
Q

made up of pixels and voxels
-field of view (FOV)
-spacial resolution dependent on matrix size

A

matrix

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15
Q

pixel

A

picture element

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16
Q

voxel

A

volume element

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17
Q

is a matrix of picture elements (pixels)

A

Digital image

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18
Q

An arrangement of cells in rows and columns
-each cell corresponds to a specific locations in the image

A

Matrix

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19
Q

Holds image in plate

A

PSP
-holding latent image

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20
Q

latent image

A

not able to see image

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21
Q

manifest

A

able to see image

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22
Q

PSP

A

photo simulator phosphor

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23
Q

what is now applied to all imaging modalities

A

-visualization of anatomy in multiple planes
-computer manipulation of imaging data through sophisticated post-processing software

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24
Q

-adjusting to image
-pre-processing
-built in
-corrects grays
-can enhance pathologies

A

Look up table

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25
Q

-determined by the number of pixels in the rows and columns
-expressed by listing the number of pixels in each dimension (length and width)
-256X256, 512X512, 1024X1024

A

Matrix size

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26
Q

-one individual cell in a matrix

A

Pixel (picture element)

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27
Q

Three values associated with each pixel:

A

-two for location (length and width)
-one for level of brightness (of shades of gray)

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28
Q

what does each pixel contain

A

bits of information
(number of bits per pixel determines the shades of gray demonstrated)

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29
Q

How is spacial resolution affected, the smaller the pixel

A

The smaller the pixels, the greater the spacial resolution
-2pixels required to image 1lp/mm

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30
Q

how is the image resolution affected with the greater the number of pixels

A

The greater the number of pixels, the greater the image resolution

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31
Q

Level of gray is a determining factor of the overall image quality

A

determines contrast resolution

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32
Q

number of bits per pixel determines the shade of gray determined

A

bit depth

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33
Q

number of gray shades that a pixel can produce

A

Bit depth

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34
Q

what bit depth does most radiography use?

A

8,10,12 bit depth

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35
Q

Changing position or orientation of pixels, allows rotation and magnification

A

Geometric Processing Operations

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36
Q

Calculations applied to small group of pixels

A

Kernel

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37
Q

-enhancing the edges (making everything look sharp), helps increase contrast

A

High pass filtering/edge enhancement

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38
Q

smooth, even and removes high frequency noise

A

low pass filtering/ smoothing

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39
Q

makes edges pop out and bring out fine detail in images

A

edge enhancements

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40
Q

blur something out in the background

A

unsharp masking or blurring

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41
Q

read left to right
white to black

A

histogram

42
Q

annotation

A

typing on it (supine, erect, AP, PA)

43
Q

putting 2-3 images together to create one

A

Stitching
ex. scoliosis series, long bone studies

44
Q

what happens to your spacial resolution when your matrix size increases and your pixel size decreases

A

spacial resolution increases

45
Q

what happens to your density resolution when the gray scale bit depth increases

A

density resolution increases

46
Q

-ability to represent small energy values in data set

A

Low contrast resolution (LCR)
-CR/DR receptors have excellent LCR
-greater dynamic range (low contrast-more shades of gray)

47
Q

Types of noise

A

-electronic (system) noise
-quantum noise

48
Q

artifact, anything unwanted in image

A

noise

49
Q

what type of signal to noise ratio is wanted

A

high signal , low noise

50
Q

Measure of how sensitive and accurate incoming data is converted to output viewing

A

Detective Quantum Efficiency (DQE)

51
Q

want close to 1 as possible, how efficient it is picking up the radiation hitting the IR
more efficient =less dose to patient

A

DQE

52
Q

DQE of 1=

A

100% or no loss of information
-higher DQE means lower dose

53
Q

-provides information about exposure to image receptor
-acceptable ranges for best image quality
-calculated using histogram values and pixel values of interest mid points
-varies between vendors

A

Exposure index (EI)

54
Q

Responsible for understanding and applying EI values

A

-assess image quality
-ALARA compliance

55
Q

calculating how much exposure going on to IR and how much radiation to the pt.

A

Exposure index (EI)

56
Q

A type of indirect digital radiography; the radiographer must usually move the detector, that is most often housed in a cassette between image acquisition and display

A

CR

57
Q

Imaging system that replace traditional film with a reusable detector

A

Digital Radiography (DR)

58
Q

Conversion of incoming xray photons to an electronic signal without scintillation

A

Direct conversion

59
Q

The number of shades of gray; ranges from 8 bits to 32 bits.

A

grayscale bit depth

60
Q

A two-part process involving a scintillator (which converts incoming x-ray photons to light) and a photodetector (which converts light into an electronic signal).

A

Indirect Conversion

61
Q

Amplifies or deletes all but the high frequencies.

A

High Pass Filtering

62
Q

Generated by dividing a scanned area into pixels and determining the signal intensity for each pixel; can be calculated for specific anatomy and procedures.

A

histogram

63
Q

Amplifies or deletes all but the low frequencies.

A

low pass filtering

64
Q

Analog to digital consists of two distinct steps

A

Sampling and Quantification

65
Q

During this step the analog voltage values are measured at a chosen sampling frequency on the analog waveform.

A

sampling

66
Q

Each sampled piece of analog data is then computed and assigned a discrete analog value,
what is this process called

A

Quantification

67
Q

means image sharpness

A

Spacial resolution

68
Q

is generated during initial processing from the image data that allows the digital system to find the useful signal by locating the minimum and maximum signal within the anatomical regions of interest in the image.

A

Histogram

69
Q

What is noise measures as

A

signal to noise ratio

-A high SNR indicates little noise in the image. Image noise has an inverse relationship to contrast. Increased noise decreases image contrast

70
Q

a comparison between the actual exposure and the proper exposure received by the image detector.

A

Deviation Index (DI)

71
Q

Describes how much of the patient is imaged in the matrix

A

Field of view (FOV)

72
Q

which of CR and DR has less patient dose

A

DR less exposure to pt.

73
Q

Requires binary machine language

A

Two symbol alphabet
need a 0 and 1 to create some image

74
Q

Direct

A

no step of light

75
Q

Indirect

A

is using light

76
Q

out of indirect and direct which captures better image

A

direct captures better quality image because 1 less step

77
Q

out of CR and DR which has the better image

A

DR

78
Q

Analog voltage values are measured at a chose sampling frequency and a analog wavelength
how image is read

A

Sampling

79
Q

each sampled piece now gets a value of 0 or a 1

A

quantification

80
Q

when you increase sampling what does that do to the quality of the image

A

increases quality of image

81
Q

pixel pitch and size is dependent on :

A

Matrix size and image receptor size

82
Q

The physical distance between pixels; generally measured from center to center.

A

pixel pitch

83
Q

determined number of assigned gray shades to pixel value

A

Bit Depth

84
Q

Greater bit depth yields:

A

greater range of gray shades

85
Q

Greater bit depth increases:

A

size of data set and volume of data for image processing

86
Q

determines number of density values
-affects density and contrast of system

A

Pixel Bit depth

87
Q

image file size is affected by:

A

Pixel size
matrix
bit depth

88
Q

DICOM

A

Digital imaging and communications in medicine
-digital standard for imaging

89
Q

Gray scale bit depth

A

ranges from 8 to 32

90
Q

image processing information

A

-point processing
-local processing
-geometric processing

91
Q

window leveling

A

up and down (brightness)

92
Q

Window width

A

Left and right (contrast)

93
Q

adjusting input image with output image

A

point processing operations

94
Q

tail or spike in histogram

A

-Densities outside the imaged anatomy
-background information
-Usually eliminated or will skew the graph

95
Q

Graphic representation of all of the pixel brightness values
in the image in the order of their brightness

A

Histogram

96
Q

what might cause a histogram error

A

from shielding or prosthesis

97
Q

under or over exposure conditions compensated for by shifting histogram to align with reference histogram

A

rescaling

98
Q

-acquired histogram compared to reference histogram
-produces consistent image appearance regardless of exposure
- dose creep

A

histogram rescaling

99
Q

-adjustments to image contrast
-produces contrast look according to reference contrast scale for exam view

A

Look up table

100
Q

what color would bone be

A

high atomic number (white)

101
Q

-high pass filtering edge enhancement
- low pass filtering/smoothing
-unsharp masking or blurring
- spatial location filtering

A

local processing operations

102
Q

Under or over exposure conditions compensated for by shifting histogram to align with reference histogram

A

Rescaling

Exposures II (7 decks)

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