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Physics - Common Equipment > Chapter 15 > Flashcards

Chapter 15 Flashcards

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1
Q

When was the first fluoroscope invented and by who?

A

1896 by Edison

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2
Q

1st fluoroscope was made with what type of screen?

A

Calcium tungstate

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3
Q

When was the image intensifier introduced?

A

1950s

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4
Q

Image intensifiers allowed for images to be _______ viewed through mirror optics and later, television monitors

A

Indirectly

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5
Q

What mA is used in fluoroscopy vs conventional x-ray?

A

Fluoro: .5 - 5 mA
Tradiational: 50 - 1200 mA

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6
Q

Benefits of low mA used in fluoro

A

Can be used for longer durtation with reduced risk of injury to the patient

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7
Q

Fluoro control panels are fitted with a timer that discountinues exposure at the __ minute mark

A

5 minute

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8
Q

What is an image intensifier and what does it do?

A

An electronic vacuum tube that converts the remnant beam to light, and then into electrons, then back into light

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9
Q

5 basic parts of the image intensifer

A

Input phosphor
Photocathode
Electrostatic focusing lenses
Accelerating anode
Output phosphor

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10
Q

The intensified light exiting the output phosphor is converted into ____________

A

electronic signal

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11
Q

Input phosphor is typically made of _____ and bonded to the _______ surface of the intensifier tube

A

Cesium iodide
Curved

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12
Q

Which phosphor is larger?

A

Input

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13
Q

What happens when radiation strikes the cesium iodide of the input phosphor?

A

Light is emitted

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14
Q

The photocathode is made of ________

A

cesium and antimony

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15
Q

After being exposed to light, the photocathode emits ______

A

electrons

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16
Q

What is the process called when the photocathode emits electrons?

A

Photoemission

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17
Q

The photocathode is curved in a way that directs the emitted electrons in same the direction, through the ____________

A

electrostatic focusing lenses

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18
Q

The focusing lenses are __________ charged plates

A

Negatively

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19
Q

The negative charge of the focusing lenses __________ the electrons in a focused direction, towards the ________

A

Repels
Accelerating anode

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20
Q

The purpose of the accelerating anode is to:

A

Direct the electrons at a consistent rate towards the output phosphor

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21
Q

The anode is supplied with a constant electric potential of:

A

25 kV

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22
Q

After exiting the accelerating anode, electrons stike the _______________

A

output phosphor

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23
Q

Output phosphor is made up of ___________

A

Silver-activated zinc cadmium sulfide

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24
Q

The output phosphor ________ electrons and coverts them into light

A

Absorbs

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25
Q

The light absorbed by the output phosphor is converted into

A

Electric signal

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26
Q

The ability of an image intensifier tube to convert radiation into light is referred to as

A

Brightness gain

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27
Q

Brightness gain =

A

Flux gain x minifiation gain

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28
Q

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

A

Flux gain

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29
Q

Flux gain represents the:

A

Systems efficiancy

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30
Q

The expression of how much an image is minified, meaning made smaller, from the input phosphor to the output phosphor

A

Minification gain

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31
Q

The expression of luminance at the output phosphor divded by the input exposure rate

A

Conversion factor

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32
Q

As the intensifier ages, it will slowly ________ it’s ability to intensify

A

Lose

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33
Q

Function that maintains the overall appearance of the image by adjusting kVp and mA as needed

A

Automatic Brightness Control (ABC)

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34
Q

When operating in magnification mode, ________ to the focusing lens within the intenisifier is ________

A

Voltage
Increased

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35
Q

What happens to the focal point when mag mode is being used

A

Shifts the focal point farther from the output phosphor (similar concept to OID)

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36
Q

Mag mode increases:

A

Spatial resolution and patient dose

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37
Q

Unequal magnification creates a form of shape distortion known as:

A

Pincushion appearance

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38
Q

The loss of brightness around the edges of the image

A

Vignetting

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39
Q

Television cameras used to display images included either:

A

Camera tubes or CCD

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40
Q

Camera tubes are the same diameter as the:

A

Output phosphor

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41
Q

Most common camera tube is the:

A

Vidicon tube

42
Q

How is the vidicon tube connected to the output phosphor

A

Fiber optics or optical lenses

43
Q

Vidicon tube is a _____ tube contained in a ______, which maintains a vacuum

A

Diode
Glass envelope

44
Q

_____ end of the vidicon tube consists of an electron gun and control grid

A

Cathode

45
Q

The electron gun in the vidicon tube provides a continous steam of _______, the control grid forms the stream into a _________

A

Electrons
Beam

46
Q

Center of the vidicon tube contains coils that provide:

A

Alignment, focus and deflection

47
Q

What is the purpose of the coils in the vidicon tube?

A

Accelerate and control the electron beam

48
Q

The coils in the vidicon tube cause the beam to follow a specific pattern called a:

A

Raster pattern

49
Q

______ end of the vidicon tube consists of a face plate, signal plate, and target

A

Anode

50
Q

The signal plate in the vidicon tube is a __________ material that conducts electricity

A

Graphite

51
Q

The target in the vidicon tube is a photoconductive layer made of:

A

Antimony trisulfide

52
Q

In plumbicon tubes, the target is made of:

A

Lead oxide

53
Q

The target in the plumbicon tubes acts as a __________ or a _________ depending on if it’s illuminated

A

Conductor or insulator

54
Q

When using CCD in place of camera tubes, a series of __________ capacitors are used, with each capactior representing an individual pixel in the image

A

Metal oxide semiconductors

55
Q

When using CCD, each pixel is made of photosensitive material that dislodges __________ when stimulated by light

A

Electrons

56
Q

When using CCD, electrodes between each pixel, called ___________, are charged in sequence, which moves the signal down the row, where it is ultimately transferred to capacitors

A

Row gates

57
Q

CCD TV cameras are _____ sensitive to a wider range of light intensity

A

More

58
Q

Are fiber optics or optical lens systems more durable?

A

Fiber optics

59
Q

Which type of connection, fiber optics or optical lens, allows for spot films?

A

Optical lens

60
Q

TV monitor converts electrical signal from camera tubes or CCD back into:

A

Visible images

61
Q

Older fluoro units used what type of monitors?

A

Cathode Ray Tube (CRT)

62
Q

How did CRT monitors function?

A

Like camera tube systems, but in reverse

63
Q

Typical monitors are called ______ line systems

A

525

64
Q

High resolution monitors have ___ lines per frame

A

1024

65
Q

Spot films are when a fluoro unit is used to take ______ images

A

Static

66
Q

Film cameras use much _____ radiaiton than cassette-spot film systems

A

Less

67
Q

Earlier versions of fluoro added in an ADC and computer between the camera tube and monitor. The ADC took the analog signal and converted it to:

A

Digital signal

68
Q

Two forms of FPD systems

A

Indirect capture
Direct capture

69
Q

The photodetector in indirect capture systems is:

A

Amorphous silicon

70
Q

Direct capture systems use:

A

Amorphous selenium

71
Q

Indirect capture uses scintillators that are made of either ________ or _______

A

Cesium iodide or gadolinium oxysulfide

72
Q

In fluoro, FPDs use a ____________ to erase the detector between each individual frame

A

Light-emitting diode array

73
Q

Current dynamic systems are capable of capturing up to _____ frames per second

A

60

74
Q

The last frame captured is held for viewing on the monitor

A

Last hold image (LHI)

75
Q

Collimation lines are visible on monitor

A

Virtual collimation

76
Q

Reduces overall dose and noise by averaging multiple frames together

A

Frame averaging

77
Q

Prebuilt algorithms that are meant to be used with specific body parts

A

Anatomic programs

78
Q

Automatically adjusts technical factors to maintain optimum exposure levels

A

Automatic exposure rate control (AERC)

79
Q

AERC can automatically adjust:

A

mA
kVp
Filtration
Pulse width

80
Q

Electronic magnification is the selection of a ______ FOV

A

Smaller

81
Q

At _____ pulses per second, the dose is about the same as continous fluoro

A

30

82
Q

Amount of pulses that occur each second

A

Pulse rate

83
Q

Length of each pulse

A

Pulse width

84
Q

The amount of kinetic energy released in matter

A

Air Kerma

85
Q

Max air kerma rate for fluoro

A

88 mGy/min

86
Q

Used to measure exposure in air

A

Dose-area product (DAP)

87
Q

Same as DAP - product of total air kerma and the area of the beam as it enters the patient

A

Kerma air product (KAP)

88
Q

Type of monitors that offer superior resolution and displayed brightness

A

Liquid crystal display (LCD)

89
Q

In LCD, the crystals within the crystal layer are ______ shaped and _________ liquid

A

Rod
Semi

90
Q

In LCD, when ___________ is applied, the crystals organize into configurations that either block or allow light to pass through

A

Electric current

91
Q

In LCD, a layer of _____ controls each individual pixel in the display

A

TFTs

92
Q

Plasma monitors use _________ instead of a liquid crystal layer

A

Thin layer of pixels

93
Q

In plasma displays, each pixel is made up of __ different subpixels, each filled with _____ and ______

A

3
Neon and xenon gas

94
Q

In plasma, each of the subpixels are coated with a different phosphor that produces:

A

red, green or blue light

95
Q

In plasma, the pixel layer is sandwiched between two _________ layers

A

Dielectric

96
Q

In plasma, when electricty is passed through the dielectric layers, the gas within each subpixel is:

A

Ionized

97
Q

In plasma, the liberated electrons release:

A

UV radiation

98
Q

In plasma, UV radiation stimulates the phosphors while producing:

A

Visible light

99
Q

Source-to-skin distance shoud be no less than _____ cm on for stationary fluoro units

A

38

100
Q

Source-to-skin distance should be no less than _____ cm for mobile units/c-arm units

A

30

Physics - Common Equipment (7 decks)

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