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Digital Imaging > Chapter 4 > Flashcards

Chapter 4 Flashcards

1
Q

psp systems are either

A

cassette based or cassette less

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2
Q

cassette based psp systems different from conventions in that the cassette is

A

simply a light proof container that protects an imaging plate from light and handling

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3
Q

The PSP cassette consist of a

A

Durable, lightweight, plastic material

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4
Q

The PSP cassette is backed by thin sheet of ____ or _____ that absorbs back scatter x-ray photons

A

aluminum or lead

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5
Q

The PSP cassette contains a ____ material to protect against static, electricity, buildup, dust collection, and mechanical damage

A

anti static
felt

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6
Q

And PSP systems imaging plate consist of several layers

A

Protective layer, phosphor or active layer, reflective layer, conductive layer, color layer, support layer, and backing layer

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7
Q

In PSP systems, the radiographic image is recorded on a thin sheet of plastic known as

A

imaging plate

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8
Q

Protective layer

A

Very thin, tough clear plastic that protects the phosphor layer

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9
Q

This is a layer of photo stimulable phosphor that traps electrons during exposure. made of barium floral halide, and this may also contain a dye that differentially absorbs the stimulating light to minimize the light spread as much as possible

A

phosphor layer

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10
Q

Layer that sends light into a forward direction when released in the cassette reader, may be black to reduce the spread of stimulating light and escape of emitted light

A

reflective layer

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11
Q

What layer absorbs and reduces static electricity?

A

Conductive layer

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12
Q

located between the active layer in the support layer that absorbs a stimulating light, but reflects emitted light

A

color layer

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13
Q

Semi rigid material that gives imaging sheet some strength

A

support layer

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14
Q

Soft polymer that protects the back of the cassette

A

Backing layer

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15
Q

Cassette base, PSP systems containing window with a

A

Barcode label

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16
Q

If the cassette was correctly orientated, that image will be displayed

A

Correct

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17
Q

and PSP, the remnant beam interacts with electrons in the barium fluorohalide crystals contained within the imaging system. This interaction stimulates, or gives energy to electrons in the crystal, trapping them in the area of the cassette known as the.

A

color or phosphor center

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18
Q

Two types of PSP readers

A

Point scan and line scan

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19
Q

Contains an optical stage, a scanning laser beam, translation mechanics, light pick up guides, a photo multiplier, a signal transformer amplifier, and an analog digital converter

A

point scan readers

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20
Q

line scan readers are based on

A

simultaneous stimulation of the imaging plate, one line at a time

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21
Q

with light scan readers, the acquisition of Photostimulated luminance occurs with a

A

CCD linear array photodetector

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22
Q

PSL refers to the

A

The emission of light from the phosphor, after stimulation by the relevant light source

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23
Q

The line scan system requires a

A

lens array to focus each laserbeam to a corresponding point on the CCD array

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24
Q

What are the two scan directions?

A

fast scan, and low scan

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25
Q

Fast scan direction

A

The movement of the laser across the imaging plate

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26
Q

slow scan direction (translation, or subscan)

A

The movement of the imaging plate through the reader

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27
Q

Light amplification of stimulated emission of radiation

A

laser

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28
Q

device that creates and amplifies a narrow, intense beam of coherent light

A

laser

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29
Q

The laser requires a

A

Constant power source to prevent output fluctuations

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30
Q

The laser beam passes through beam shaping object to an

A

Optical mirror that directs the laser beam to the surface of the imaging plate

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31
Q

During the reading process, the imaging plate is scanned with a

A

Helium laser beam (more recently a solid state laser diode)

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32
Q

The laserbeam is about ____ wide, with a wavelength of _____

A

100 micrometers
633 nanometers

(670-690 for solid state )

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33
Q

The laserbeam scan the plate with a

A

Red light in a raster pattern

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34
Q

The red laser light is admitted at approximately

A

Two electron volts, which is necessary to energize the trapped electrons

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35
Q

The energy from the red laser light allows the trapped electrons to escape the active layer where the emit visible blue light at an energy of

A

3 electron volts as they relax to lower energy levels

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36
Q

As the imaging plate moves through or remain stationary in the reader, the laser scans across the imaging plate

A

Multiple times

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37
Q

The plate movement through the scanner is known as translation, because

A

Because it moves in a parallel manner at a certain rate through the reader

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38
Q

As the imaging plate is being scanned the process produces lines of light intensity information that are detected by a

A

Photodetector

39
Q

Amplifies a light and send it to the ADC

A

Photo detector

40
Q

The translation speed of the plate must be coordinated with the skin direction of the laser or the

A

Spacing of the scan lines will be affected

41
Q

The more angled the beam is the more

A

Elliptical in the shape of the beam

42
Q

The beam is shaped by special _____ that keeps the beam size, shape, and speed, largely independent of the beams position

A

optics

43
Q

A beam deflector moves the laser beam rapidly back-and-forth across the imaging plate to stimulate the

A

phosphors

44
Q

because the type of phosphor material in the imaging plate has an effect on the amount of energy required

A

Did laser in the imaging plate should be designed to work together

45
Q

The typical throughput is _____ cassettes per hour

A

50

46
Q

Digitizing a signal

A

The signing a numerical value to each light photon

47
Q

In film screen radiographic resolution at its best is limited to

A

10 LP/MM

48
Q

PSP imaging resolution is approximately

A

2.5- 5 LP/MM

49
Q

Resolution detail is affected by the

A

Laserbeam spot size, translation speed, sampling, frequency, and laserbeam sweep

50
Q

The smaller the diameter of the laserbeam

A

The higher the spatial resolution

51
Q

Slower translation speed all allows more

A

Exposure to be detected

52
Q

The higher the sampling frequency the more

A

exposure detected

53
Q

Imaging plates are extremely sensitive to scatter radiation and should be

A

Erase to prevent a buildup of background signal

54
Q

At least, once a week, the plates should be ran through a

A

Erase cycle to remove background radiation, and scatter

55
Q

Systems automatically erase the plate by flooding it with

A

Light to remove any electrons, trapped after the initial reading

56
Q

When using a cassette base system, the selection of the body part is usually done

A

After exposure

57
Q

traditionally, KVP was chosen for _____ and _____, and mAs according to the

A

penetration and tissue type

number of photons required for that body part

58
Q

KVP values range from _____ to ____ of most digital projection systems

A

45-120

59
Q

The k edge of phosphor imaging plates ranges from ___ to ___

A

30-50 kEv

60
Q

The process of _____ is exactly the same in film

A

attenuation

61
Q

Major difference between film and digital is the image contrast is no longer dependent on

A

kvp

62
Q

in digital imaging contrast is determined by

A

Computer processing

63
Q

Two important factors should be considered when selecting the PSP imaging cassette

A

type and size

64
Q

Two types of imaging plates

A

Standard and high resolution

65
Q

Cassette should be marked on the outside to indicate

A

high resolution imaging plates

66
Q

High resolution, imaging plates contain a ____ compared to the standard plates

A

Thinner phosphor layer

67
Q

The thinner phosphor layers result in greater image sharpness, because of the

A

Reduced amount of light spread

68
Q

light spread can occur with any image capture system that involves

A

Release of light

69
Q

High resolution imaging plates are limited to

A

Smaller cassette size is used for extremities mammography

70
Q

The oscillating motion of a moving grid or buck blurs the grid lines and eliminates the

A

moire effect

71
Q

PSP systems are more sensitive to low levels of radiation so the use of ____ is important

A

grid

72
Q

Grid selection factors

A

Frequency, ratio, and focus

73
Q

The number of gridlines per inch or centimeter

A

grid frequency

74
Q

The higher the grid frequency or more lines per inch

A

The finer the grid lines in the image, and less they interfere

75
Q

Typical grid frequencies

A

80-152 lines /inch

76
Q

some manufacturers recommend no fewer than ___ lines per inch, and strongly suggest grid frequencies greater than ____

A

103, 150

77
Q

The closer the grid frequency is to the laser scanning frequency, the greater likelihood of frequency harmonics, or matching, and the more likely the risk of

A

moire effects

78
Q

The ratio of the height of the lead strips to the distance between them

A

Grid ratio

79
Q

Grade ratios of ___ would be good for mobile

A

6:1

80
Q

Grid ratios of ____ would be good for departmental

A

12:1

81
Q

Most grids chosen by radiography departments are

A

parallel and focused

82
Q

Parallel grids are less critical to beam centering, but should not be used at a distance less than

A

48 inches

83
Q

Consist of lead strips, angled to coincide with the divergence of the x-ray beam, and must be used with specific distances using a precisely centered beam

A

focused grid

84
Q

Increasing the collimation

A

Increases the contrast

85
Q

this is extremely important and establishing the parameters that determine collimation borders and edges and histogram formation

A

image recognition phase

86
Q

Image, recognition, phase
agfa uses the term

A

collimation

87
Q

image recognition phase
carestream

A

segmentation

88
Q

image recognition phase
fuji

A

Exposure data, recognition

89
Q

For common types artifacts

A

Image plate artifacts
imaging processing artifacts
Plate reader artifacts
printer artifacts

90
Q

this artifact can happen because of incorrect part, chosen on control panel
incorrect sampling
Poor technique

A

image processing artifact

91
Q

Intermittent appearance of the extraneous line pattern that can be caused by problems in the electronics of the plate reader

A

plate reader artifacts

92
Q

The gridlines must be ____ to the laser scan direction

A

perp

93
Q

Artifact to wear fine white lines may appear on the image because of debris on the mirror in the laser printer

A

printer artifacts

Digital Imaging (1 decks)

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