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RT 209 > 8. Image-Intensified Fluoroscopy > Flashcards

8. Image-Intensified Fluoroscopy Flashcards

1
Q

to aid the radiologist in dynamic studies of the human body

A

Fluoroscopy

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2
Q

“real time” imaging

A

Fluoroscopy

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3
Q

Thomas Edison invented the fluoroscope (calcium tungstate screen) year

A

1896

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4
Q

William Chamberlain studies on the poor illumination from fluoroscopic screen year

A

1941

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5
Q

development of image intensifier tube year

A

1950’s

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6
Q

measure in units of Lamberts (L) and millilamberts (mL) (SI unit-lumens)

A

Illumination

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7
Q

Radiographs are viewed under illumination level of ____

A

10 to 1000 mL

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8
Q

Human vision– rods and cones

A
  • Photopic and scotopic vision

* Visual acuity

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9
Q

Fluoroscopic Chain

A
  • Image intensifier
  • Recording system
  • Viewing system
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10
Q

electronic vacuum tube that converts the remnant beam to light then to electrons, then back to light, increasing the light intensity in the process

A

Image intensifier

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11
Q

complex electronic device that receives the remnant x-ray beam, coverts it into light, and increases the light intensity

A

Image intensifier

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12
Q

it brightened the image significantly

A

Image intensifier

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13
Q

allows for a means to indirectly viewing the fluoroscopic image

A

Image intensifier

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14
Q

Basic Parts of an Image Intensifier

A
  • Input Phosphor
  • Photocathode
  • Accelerating Anode
  • Output Phosphor
  • Electrostatic Focusing lenses
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15
Q

Input Phosphor is made of

A

Cesium Iodide (CsI)

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16
Q

Converts energy to visible light

A

Input Phosphor

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17
Q

CsI crystals are tightly packed as ____ layer

A

100 to 200 micrometer

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18
Q

composed of Cesium and antimony compounds

A

Photocathode

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19
Q

emit electrons when stimulated by light (photoemission)

A

Photocathode

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20
Q

maintains constant potential of approximately 25 kV

A

Accelerating Anode

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21
Q

electrons interact to produce light

A

Output Phosphor

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22
Q

usually made of silver-activated zinc-cadmium sulfide

A

Output Phosphor

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23
Q

engineering aspects of maintaining proper electron travel

A

Electron Optics

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24
Q

located along the length of image intensifier tube

A

Electrostatic Focusing Lens

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25
Q

not really lenses, but are negatively charged plates along the length of the Image Intensifier tube

A

Electrostatic Focusing Lens

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26
Q

approximately 50 cm in length and 15 to 58 cm in diameter

A

Image Intensifier Tube

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27
Q

high energy electrons that interact with the output phosphor each result in substantially more light photon than was necessary to cause their release at the photocathode

A

Image Intensifier Tube

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28
Q

Parts of Image Intensifier

A
  • Output Window
  • Output Phosphor
  • Photocathode
  • Input Window
  • Input Phosphor
  • Evacuated Tube
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29
Q

the ratio of the number of light photons at the output phosphor to the number of x-rays at the input phosphor

A

Flux Gain

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30
Q

represents the tube’s conversion efficiency

A

Flux Gain

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31
Q

Flux Gain=

A

Flux Gain = number of output light photons/ number of input x-ray photons

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32
Q

an expression of the degree to which the image is minified from the input phosphor to output phosphor

A

Minification Gain

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33
Q

the ratio of the square of the diameter of the input phosphor to the square of the diameter of the output phosphor

A

Minification Gain

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34
Q

this characteristic makes the image brighter because the same number of electrons is being concentrated on a smaller surface area

A

Minification Gain

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35
Q

output phosphor size is fairly standard at _____

A

2.5 or 5 cm

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36
Q

input phosphor size varies from ___

A

10 to 35 cm

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37
Q

brightness gain of most image intensifiers is ____

A

5000 to 20,000

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38
Q

is an expression of the ability of an image intensifier tube to covert x-ray energy into light energy and increase the brightness of the image in the process

A

Brightness Gain

39
Q

the ability of the image-intensifier tube to increase the illumination level of the image

A

Brightness Gain

40
Q

Brightness Gain =

A

Brightness Gain = minification gain x flux gain

41
Q

is an expression of the luminance at the output exposure rate

A

Conversion Factor

42
Q

recommended by the ICRU to quantify the increase in brightness created by Image intensifier

A

Conversion Factor

43
Q

as an image intensifier ages, the exposure rate to the patient ____ to maintain brightness

44
Q

a function of the fluoroscopic unit that maintains the overall appearance of the fluoroscopic image by automatically adjusting the kVp, mA or both

A

Automatic Brightness Control (ABC)

45
Q

the voltage to the electrostatic focusing lenses is increased

•the increase tightens the diameter of the electron stream and the focal point is shifted farther from the output phosphor

A

Magnification Mode or Multi-field Mode

46
Q

the effect is that only those electrons from the center area of the input phosphor interact with the output phosphor and contribute to the image, giving the appearance of magnification

A

Magnification Mode

47
Q

may be found by dividing the full-size input diameter by the selected input diameter

A

degree of magnification (MF)

48
Q

degree of magnification (MF) =

A

MF = 30 / 15 = 2 x magnification

49
Q

improves the fluoroscopist’s ability to see small structures (spatial resolution) but at the price of increasing patient dose

A

Magnification

50
Q

Fluoroscopic systems – ____ Lp/mm

A

4 to 6 Lp/mm

51
Q

is a result of inaccurate control or focusing of the electrons released at the periphery of the photocathode

A

Distortion

52
Q

combined result in unequal magnification

A

pincushion appearance

53
Q

reduction of brightness at the periphery

A

Vignetting

54
Q

results when insufficient information is present to create the image

A

Image Noise

55
Q

insufficient quantity of x-rays

A

Image Noise

56
Q

“grainy” or “noisy” image

A

Image Noise

57
Q

Fluoroscopic Image Monitoring parts

A
  • Camera Tube

* Charged-coupled Device (CCD)

58
Q

converts the light image into electric signal

A

Camera Tube – the television camera tube

59
Q

are most often used television camera tube used in fluoroscopy

A

Vidicon and plumbicon

60
Q

provides continuous stream of electrons

A

Electron gun

61
Q

forms the electron streams into a “beam”

A

Control grid

62
Q

Electromagnetic coils

A
  • Deflection coils
  • Focusing coils
  • Alignment coils
63
Q

act to accelerate and precisely control the electron beam

A

Electromagnetic coils

64
Q

Through this action, the beam sweeps the anode back and forth from top to bottom in a sequence known as _____

A

Electromagnetic coils,

raster pattern

65
Q

light-sensitive semiconducting device that generates an electrical charge when stimulated by light and stores this charge in a capacitor

A

Charged-Coupled Device

66
Q

the charge is proportional to the light intensity and is stored in rows and pixels

A

Charged-Coupled Device

67
Q

is a series of metal oxide semiconductor capacitors, with each capacitor representing a pixel

A

Charged-Coupled Device (CCD)

68
Q

Coupling the Television Camera

A
  • Fiber-optics bundle

* Lens-coupling

69
Q

simply a bundle of very thin optical glass filaments

A

Fiber-Optics Bundle

70
Q

very durable and simple in design but does not allow for spot filming

A

Fiber-Optics Bundle

71
Q

series of optical lenses that focus the image from the output phosphor on the camera tube

A

Optical Lens System

72
Q

Susceptible to rough handling, which may cause maladjustment of the mirrors and lenses and result in a blurred image

A

Lens-coupling

73
Q

Beam-splitting mirror enables ____

A

spot filming

74
Q

heart of television monitor

A

Television Monitor – television picture tube (cathode ray tube)

75
Q

convert the electronic signal from the camera tube or CCD back into a visible image

A

Television Monitor – television picture tube (cathode ray tube)

76
Q

Television Monitor – television picture tube (cathode ray tube) - ___ Lp/mm

A

1 to 2 Lp/mm

77
Q

the camera tube and CCD are devices that couple the image intensifier to the television monitor to convert the image from the output phosphor to an electronic signal that can be reconstructed on the television monitor

A

Coupling Systems and Television Monitor

78
Q

Recording Systems

A
  • Cassette Spot Film
  • Film Camera
  • Video Recorders
79
Q

static imaging process in which a standard radiographic cassette is used to obtain an image

A

Cassette Spot Film

80
Q

The unit shifts to radiographic mode and the radiation dose to the patient is much higher than in fluoroscopic mode

A

Cassette Spot Film

81
Q

sometimes called photo-spot cameras

A

Film Cameras

82
Q

commonly use 105-mm “chip:film or 70-mm roll film

A

Film Cameras

83
Q

static imaging that is used with an optical lens system incorporating a beam-splitting mirror

A

Film Cameras

84
Q

used when dynamic imaging is desired

A

Video Recorders

85
Q

useful in functional studies of the esophagus or placement of catheters or medical devices, for example

A

Video Recorders

86
Q

used analog-to-digital converter (ADC)

A

Digital Fluoroscopy

87
Q

computer between the camera tube and the monitor

A

Digital Fluoroscopy

88
Q

a device that takes the video (analog) signal and divides in into a number of bits (1s and 0s) that the computer “understands”

A

Analog-to-Digital Converter (ADC)

89
Q

the number of bits that the signal is divided into determines the contrast resolution of the system

A

Analog-to-Digital Converter (ADC)

90
Q

eliminated some of the problems associated with the camera tube

91
Q

more light-sensitive (higher DQE) and exhibits less noise and no spatial distortion

92
Q

higher spatial resolution and less radiation

93
Q

Flat-panel Detectors

A
  • Cesium iodide amorphous silicon indirect capture

* amorphous selenium direct-capture detector

94
Q

Advantages of Digital Fluoroscopic Systems compared to Image Intensifier

A
  • Reduction in size, bulk and weight of the fluoroscopic tower, allowing for easier manipulation, greater access to patient during examination
  • Replace spot filming and other recording devices
  • Can be readily archived with the patient record in PACS
  • Does not degrade with age
  • More durable
  • Better contrast resolution
  • Higher DQE
  • Wider dynamic range
  • Post-processing options
  • Do not exhibit most image artifacts such glare and peripheral distortion
  • Lower patient dose

RT 209 (11 decks)

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