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Exposures ll (mine) > Chapter 20: Digital Image Processing > Flashcards

Chapter 20: Digital Image Processing Flashcards

1
Q

Two types of digital radiography systems

A
  • CR
  • DR
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2
Q

This type of digital radiographer deals with photostimulable imaging plates (PSP, IP)

A

CR

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3
Q

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

A

DR

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4
Q

When were most of the changes made for historical development?

A

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

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5
Q

Referred to as flat panel detectors (panels)

A

DR receptors

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6
Q

What type of digital radiography system does healthcare reimbursement encourage?

A

DR

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7
Q

What type of digital radiographer produces a better picture and uses less exposure to the patient, which decreases patient dose?

A

DR

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8
Q

No step of light without a scintillator, which captures a better image, requires less steps to get the image. Is directly converted into electrical signal

A

Direct conversion

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9
Q

Using light with scintillator can throw artifact. X-ray photons are converted to light photons. and a photodetector (which converts light into an electronic signal)

A

Indirect conversion

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10
Q

What is the disadvantage of indirect conversion?

A

It produces light in all directions which reduces spatial resolution

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11
Q

What is the type of material inside the CR plate?

A

Photostimulator phosphor (PSP)

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12
Q

Are the elements that capture the image and hold it in place for CR? Also holds your laten image

A

Photostimulator phosphor (PSP)

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13
Q

When you take an image is run through a processor and it takes 60 seconds for the image to show up?

A

CR

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14
Q

Not able to see the image

A

latent image

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15
Q

Visualize image you are able to see the image on the computer?

A

Manifest image

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16
Q

Is part of the post-processing where you can write on it ( AP, Supine, etc)?

A

Annotations

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17
Q

Electrical signals from receptors are converted to what?

A

Converted to analog format

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18
Q

Converts an analog signal from the image receptor or detector to a digital signal or language for the computer to manipulate for processing, display, and storage? (converting all that information to a digital picture)

A

Analog-to-digital conversion (ADC)

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19
Q

What are considered the binary numbers to be able to create the image?

A

0 and 1

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20
Q

How many bits are in 1 byte?

A

There’s 8 bits in 1 byte

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21
Q

ADC involves what two distinct steps?

A
  • Sampling
  • Quantification
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21
Q

Computer memory and power expressed in total bytes

A

-megabytes, gigabytes, terabyes, etc

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22
Q

Analog voltage value are measured at a chosen sampling frequency and an analog wavelength

A

Sampling

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23
Q

How the image is read

A

Sampling frequency

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24
Q

Sampling frequency is associated with what type of digital?

A

CR

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25
Q

(CR) increase sampling frequency

A

increase the quality of the image (spatial resolution)

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26
Q

means image sharpness

A

Spatial resolution

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27
Q

each sample piece now gets a number value and is assigned a binary number of 0 and 1

A

Quantification

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28
Q

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

A

Matrix

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29
Q

Picture element

A

Pixel

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30
Q

volume element
- 3 dimentional

A

Voxel

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31
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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32
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)
- common sizes: 256x256, 512x512

A

Matrix size

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33
Q

One individual cell in a matrix
- also known as the picture element

A

Pixel

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34
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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34
Q

The smaller the pixel

A

the greater the spatial resolution

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35
Q

what does each pixel contain

A

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

36
Q

The greater the number of pixels

A

the greater the image resolution

36
Q

How many pixels are required to image 1lp/mm

A

2 pixels

37
Q

When you increase your matrix and decrease your pixel what happens to your spatial resolution?

A

Spatial resolution increases

38
Q

Number of gray shades that a pixel can produce

A

Bit depth

38
Q

What is the formula for bit depth

A

2 to the n power

39
Q

The higher the 2 to the n power

A

the more shades of gray there is

40
Q

What bit depth does most radiography use?

A

8,10, or 12 bit depth

41
Q

Determines the size of the area to be imaged / how much of the patient is imaged in the matrix?

A

Field of View (FOV)

42
Q

Pixel size=

A

FOV/Matrix size

43
Q

Matrix can be changed without affecting what?

A

The FOV and vice versa

44
Q

The distance between center of one pixel to center of adjacent pixel

A

Pixel pitch

44
Q

The smaller the pixel pitch and pixel size

A

The better the spatial resolution

45
Q

The image file size (storage) is affeccted by:

A
  • pixel size
  • matrix
  • bit depth
46
Q

Your matrix, bit depth, look-up table and histogram are all what

A

Already bulit in

47
Q

Able to transfer images to different hospitals. Communication between hospitals

A

Digital Imaging and Communications in Medcine (DICOM)

48
Q

Has a built in picture perfect image that is comparing to that’s why is important to pick the correct body part

A

Histogram

49
Q

Gray scale bit depth ranges from what

A

range from 8 to 32 bits

49
Q

Is read from left to right
white to black

A

Histogram

49
Q

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

A

Histogram

50
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

51
Q

Determines image contrast and the gray scale representation of the tissue
- left and right

A

window width

52
Q

Determines brightness of an image
- up and down
ex. think of a window shade, incresed (open) is brighter

A

window level

53
Q

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

A

Look-up table (LUT)

54
Q

What might cause a histogram error

A

shielding and prosthesis

54
Q

Considered to be white on in image

A

shielding, bone, soft tissue and air

55
Q

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

A

rescalling

56
Q

the lower atomic #

A

the more tranmission to the IR

57
Q

helps increase contrast

A

high-pass filtering

57
Q

enchancing the edges nice and sharp (lip linear)

A

High-pass filtering

57
Q

not adjusting to lower technique increasing radiation exposure over time in an attempt to achieve better image quality

A

Dose creep

58
Q

making the picture even smoother

A

low-pass filtering

58
Q

makes the edges pop out. helps bring out fien details in the image

A

edge enhancement

59
Q

changing and switching the colors of an image

A

inversion

59
Q

long bone study stiching 2 or 3 images together to make one large picture

A

stiching

60
Q

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

A

tail or spike in histogram

61
Q

You want a high signal

A

low noise

62
Q

Ability to represent small energy values in data set

A

Low contrast resolution

63
Q

The greater the dynamic range

A

the more shades of gray

63
Q

How efficient it is in picking up the radiation that is hitting the IR

A

Detective Quantum Efficiency (DQE)

63
Q

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

A

Detective Quantum Efficiency (DQE)

63
Q

want close to 1 as possible
more efficient =less dose to patient

A

Detective Quantum Efficiency (DQE)

64
Q

DQE of 1=

A

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

65
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

EI#

66
Q

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

A

Exposure index (EI)

67
Q

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

A

Deviation Index (DI)

68
Q

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

A

Pixel Bit depth

69
Q

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

A

histogram rescaling

70
Q

what color would bone be

A

high atomic number (white)

71
Q

What is noise measures as

A

signal to noise ration

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

72
Q

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

A

density resolution increases

73
Q

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

A

Look up table

74
Q

The ability of the imaging system to distinguish between small objects that attenuate the x-ray beam in a similar manner; improves the visibility of the minimum density differences or shades of gray

A

contrast resolution

75
Q

increase bit depth

A

increase contrast resolution

76
Q

wider window width ( low contrast and long scale)

A

increase contrast resolution

77
Q

blur something out in the background

A

unsharp masking or blurring

Exposures ll (mine) (9 decks)

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