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RT 212 > 3. Computed Radiography: Physics and Technology > Flashcards

3. Computed Radiography: Physics and Technology Flashcards

1
Q

TERMS SYNONYMOUS WITH CR

A
  1. Photostimulable Luminescence Radiography (PSL)
  2. Storage Phosphor Radiography (SPR)
  3. Digital Luminescence Radiography (DLR)
  4. Photostimulable Storage Phosphor Radiography
  5. Digital Storage Phosphor Radiography (DSP)
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2
Q

PSL

A

Photostimulable Luminescence Radiography

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3
Q

SPR

A

Storage Phosphor Radiography

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4
Q

DLR

A

Digital Luminescence Radiography

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5
Q

DSP

A

Digital Storage Phosphor Radiography

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6
Q

was discovered at the base of a volcano near Bologna

A

Bolognese stone

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7
Q

Bolognese stone was discovered by ____ in ____

A

Vincenzo Cascariolo, 1603

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8
Q

when treated with heat and exposed to sunlight it would glow for hours or days

A

Bolognese stone

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9
Q

CR imaging system was commercialized for use in digital radiography in ____ by ____

A

1983,

Fuji

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10
Q

introduced their FCR-101 unit (Fuji Computed Radiography-101 unit)

A

Fuji

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11
Q

FCR-101 unit

A

Fuji Computed Radiography-101 unit

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12
Q

was the pioneer of CR

A

Fuji

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13
Q

4 MANUFACTURERS ENGAGED IN CR RESEARCH, TECHNOLOGY DEVELOPMENT AND MARKETING

A

Fuji
Kodak
Agfa Gavert (Belgium)
Konica

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14
Q

Bolognese stone discovered in Italy

A

1603

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15
Q

Notion of de-excitation described by Becquerel

A

1867

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16
Q

Hirsch proposed way to retain fluorescent image by using storage phosphor-heat to restimualte and red light to erase

A

1926

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17
Q

KODAK patented an apparatus that used infrared-stimulable phosphor to store image

A

1975

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18
Q

FUJI patented process in which photostimulable phosphor was used to record image by absorbing radiation and then releasing stored image when stimulated by helium-neon laser

A

1980

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19
Q

FUJI’s first Commercialized Computed Radiography (FCR 101)

A

1983

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20
Q

FCR 201

A

1985

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21
Q

FCR 7000

A

1989

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22
Q

KODAK’s first commercial storage phosphor unit

A

1992

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23
Q

Agfa-Gavaert introduces CR Imaging Technology

A

1994

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24
Q

Others in CR Research include GE Medical Systems, Philips, Konica, etc.

A

2001

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25
Q

Fuji, Kodak, and Agfa actively engaged in research and development of state-of-the-art CR systems

A

Present

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26
Q

4 STEPS OF CR IMAGING

A
  1. Image Acquisition
  2. Imaging Plate Scanning and Erasure
  3. Image Processing
  4. Image Display, Storage and Communications
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27
Q

there are secondary steps that must be considered, the “implementation issues”

A

AAPM (American Association of Physicists in Medicine)

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28
Q

AAPM

A

American Association of Physicists in Medicine

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29
Q

AAPM (American Association of Physicists in Medicine) –there are secondary steps that must be considered, the “implementation issues”

A
  1. Practical use of CR

2. Technical concerns such as: use of grids, radiation exposure, and technique selection

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30
Q

x-ray exposure of the phosphor plate storage, or imaging plate (IP)

A

Image Acquisition

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31
Q

• Refers to the mechanism of X-ray interaction with the phosphor to produce a latent image and subsequent scanning of the IP by a laser beam to produce photostimulable luminescence (PSL)

A

Image Acquisition

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32
Q

the scanning of the IP takes place in the imaging plate reader/processor

A

Imaging Plate Scanning and Erasure

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33
Q

This readout process essentially consists of laser scanning, detection, conversion of the PSL and digitization of the signal by the analog-to-digital converter (ADC)

A

Imaging Plate Scanning and Erasure

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34
Q

use of several digital operations for pre-processing and post-processing of the CR image data

A

Image Processing

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35
Q

shading corrections, pattern recognition and exposure field recognition

A

Pre-processing

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36
Q

contrast enhance (grayscale), edge enhancement (spatial frequency)

A

Post-processing

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37
Q

uses special algorithm to create separate images of bone and soft tissue

A

Energy subtraction

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38
Q

the RT determines and assess the overall image quality of the image and subsequently send the image to the PACS

A

Image Display, Storage and Communications

39
Q

once in the _____ images are retrieved for interpretation by a radiologist

A

PACS

40
Q
  1. A digital radiographic imaging modality in which a digital detector is used to capture x-rays transmitted through the patient
A

Computed Radiography

41
Q
  1. CR is based on the phenomenon of ______ that is exhibited by photostimulable phosphors, which when struck by x-rays, creates latent image
A

photostimulable luminescence

42
Q
  1. The ______ is rendered visible when the detector is scanned by a laser beam to produce light (photostimulable luminescence) that is subsequently converted in electrical signals
A

latent image

43
Q
  1. These signals are digitized and processed by a computer that produces the CR image using
A

special digital image processing algorithms

44
Q

Commonly used phosphor material is

A

barium fluorohalide

45
Q

is positioned within the cassette or imaging plate (IP)

A

Photostimulable phosphor (PSP) screen

46
Q

The phosphor particulates are bonded with a cohesive material forming a ____ structure and deposited on a base for mechanical support

A

turbid

47
Q

CR is based on certain halide-based phosphors having energy storage and excitation characteristics known as photostimulable luminance (PSL) which:

A
  1. Enable phosphors to store x-ray energy

2. Release that energy upon excitation by a laser beam

48
Q

Standard resolution IP characteristics

A
  • Thick phosphors layers
  • Absorbs more radiation
  • Faster speed
49
Q

High resolution IP characteristics

A
  • Thinner phosphor layers
  • Sharper images
  • Extremity imaging (small parts)
50
Q

CR IMAGE PROCESSING

A
  • When the photostimulable phosphor (PSP) screen is exposed to x-rays, a fraction of that energy is stored
  • After exposure the IP is inserted in to a CR reader
51
Q

•The IP is processed by a scanning system or reader which:

A
  1. Extracts the (PSP) screen from the cassette
  2. Moves the screen across a high intensity scanning laser beam
  3. Blue-violet light is emitted via PSL
  4. Light energy is read by a PMT, which converts the light into an electrical signal
52
Q

a high intensity white light dumps all the remaining energy traps allowing the plate to be re-used thousands of times (Approximately up to 10,000 times before a new phosphor is needed)

A

Erasing the screen

53
Q

could erase by placing against view box for several minutes

A

Erasing the screen

54
Q

replaces Darkroom and Processor and Chemicals

A

QC – Reader

55
Q

replaces film, storage and view boxes

A

Diagnostic Viewer

56
Q

are housed in cassettes similar to conventional film-screen cassettes, with the IP replacing the film, and there are no intensifying screens

A

Imaging plates

57
Q

LAYERS OF THE IMAGING PLATE

A
  1. Protective layer
  2. Phosphor layer
  3. Reflective layer
  4. Conductive layer
  5. Color layer
  6. Support layer
  7. Backing layer
58
Q

this is a very thin, tough, clear plastic that protects the phosphor layer

A

Protective layer

59
Q

or active layer, this a layer of photostimulable phosphor that “traps” electrons during exposure

A

Phosphor layer

60
Q

contains light absorbing dye to prevent light spread

A

Phosphor layer

61
Q

this is a layer that sends light in forwards direction when released in the cassette reader

A

Reflective layer

62
Q

some detail is lost in this process

A

Reflective layer

63
Q

this a layer of material that absorbs and reduces static electricity

A

Conductive layer

64
Q

newer plates may contain this layer, located between the active layer and the support, that absorbs the stimulating light but reflects emitted light

A

Color layer

65
Q

this is a semi-rigid material that gives the imaging sheet some strength

A

Support layer

66
Q

this is a soft polymer that protects the back of the cassette

A

Backing layer

67
Q

absorbs backscatter

A

Backing layer

68
Q

the barcode label is found here

A

Backing layer

69
Q

allows the technologists to match the image information with the patient identifying barcode on the examination request

A

Barcode label or barcode sticker

70
Q

indicate the appropriate orientation of the cassette in relation to the patient

A

Marker / Orientation label

71
Q

the tube side in conventional radiography

A

Marker / Orientation label

72
Q

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

A

Laser (Light Amplification of Stimulated Emission of Radiation)

73
Q

Laser

A

Light Amplification of Stimulated Emission of Radiation

74
Q

Bone

A

small signal (white) [radiopaque]

75
Q

Soft tissue

A

medium signal (grey)

76
Q

Air

A

large signal (black) [radiolucent]

77
Q

meets the requirements

A

Barium Fluro Halide: Europium (BaFX:EU2+)

78
Q

Phosphors should have good X-ray absorption efficiency and must be capable of being stimulated by a

A

helium neon (HeNe) laser

79
Q

The luminescence light must be compatible with the ________ (for proper detection and capture)

A

PMT (photomultiplier tube) phosphor

80
Q

Time for luminescence must be

A

< (lesser) 1 microsecond

81
Q

Phosphors should be able to store the latent image for a number of _____ without comprising the signal from the IP

A

hours

82
Q

Instead of halide, these could be used:

A

•chlorine (Cl)
•bromine (Br)
•iodine (I),
or a mixture of them

83
Q

The phosphor is usually doped with ______, which acts as an activator to improve the efficiency of PSL

A

EU2+ (Europium)

84
Q

Other phosphors used in CR is

A

BaFBr/I :Eu2+ (Barium Fluro Bromide or Iodide doped with Euporium)
and
CsBr:Eu2 (Cesium Bromide doped with Euporium)

85
Q

Farbe

A

color (German word)

86
Q

German word for F-center

A

Farbe

87
Q

CR TECHNOLOGY IN THREE STEPS

A
  1. Instead of film, an imaging plate is exposed to X-ray
  2. The imaging plate is digitized by the scanner and then erased for immediate reuse
  3. The digital image is then displayed on a computer monitor for evaluation with specialized software
88
Q

wavelength of bluish-purple light

A

415 nm λ

89
Q

wavelength of lasers today

A

680 nm

90
Q

wavelength of HeNe lasers

A

633 nm

91
Q

BASIC PHYSICS OF CR IMAGE FORMATION

A
  1. Photostimulable phosphors have the property of creating and storing a latent image when exposed to x-rays
  2. To render the latent image visible, the PSP must be scanned by a laser beam of a specific wavelength
  3. Laser scanning produces a luminescence (light) that is proportional to the stored latent image
  4. This luminescence is referred to as photostimulated luminescence (PSL)
  5. After laser scanning, the PSP IP is erased by exposing it to a high intensity light beam to get rid of any residual latent image
  6. This step is important so that the IP can be used again and again for several x-ray exposures
92
Q

NATURES of PSP’s

A

The phosphors used in radiology must have certain physical characteristics to be useful in CR imaging

  1. Phosphors should have good X-ray absorption efficiency and must be capable of being stimulated by a helium neon (HeNe) laser
  2. The luminescence light must be compatible with the PMT (photomultiplier tube) phosphor (for proper detection and capture)
  3. Time for luminescence must be < 1 microsecond
  4. Phosphors should be able to store the latent image for a number of hours without comprising the signal from the IP
93
Q

HOW PHOSPHORS WHEN STIMULATED BY X-RAYS (SCANNING AND PROCESSING THE IMAGING PLATE)

A
  1. When the x-rays fall upon the PSP IP
  2. The europium atoms are ionized by the radiation
  3. The electrons move from the valence band (ground state) to conduction band (higher energy)
  4. Electrons in the conduction band are free to travel to a so-called “F-center” (Farbe [German word] =color)
  5. The number of trapped electrons is proportional to the absorbed radiation
  6. At this point, the electrons are spatially distributed to create the latent image
  7. X-ray exposure of the IP causes it to fluorescence (emit light when it is exposed to X-rays) for a very brief duration
  8. To render the latent image visible, the PSP IP is taken to the CR reader/processor to be scanned by a laser beam (photostimulable excitation)
  9. While in the CR reader, the PSP IP is scanned systematically
  10. The laser light used must be capable of being absorbed by the F-centers (Helium-Neon)
  11. This absorption causes the trapped electrons to move up to the conduction band, where they are free to return to the valence band, thus causing the Eu3+ to the Eu2+ state
  12. This transition of the electrons from a higher energy state to a lower energy state (ground state) results in an emission of bluish-purple light (415 nm λ)
  13. Referred to as photostimulable luminescence (PSL) in the IP

RT 212 (10 decks)

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