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Rad105 > Test 5 - Chpt 15 & 16 > Flashcards

Test 5 - Chpt 15 & 16 Flashcards

1
Q

Who invented the first commercial fluoroscope and when

A

Thomas Edison
1896

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2
Q

When was the image intensifier introduced and what did it do

A

1950s
- brightened image and made indirect viewing possible

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3
Q

What uses low mA compared to the mA used in radiographic mode (50-1200mA)

A

Image intensified fluoroscopy uses (0.5-5mA)

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4
Q

Why is low mA used for fluoroscopy?

A

Allows for increased exposure time

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5
Q

How is the continuous beam activated in fluoroscopy?

A

Uses a deadman’s switch
- releasing pressure applied terminates radiation exposure

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6
Q

The input phosphor faces the patient, absorbs the ______ and emits ______ in response

A

Remnant beam
Light

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7
Q

Emitted light exposes the photocathode which emits _______ in proportion to the __________

A

Electrons
Light intensity

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8
Q

(T/F) fewer light photons are needed to result in one emitted electron

A

False
Many light photons

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9
Q

Emitted electrons are accelerated to the output phosphor by the accelerating _____ and focused on the output phosphor by the _______________

A

Anode
Electrostatic focusing lenses

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10
Q

High energy electrons result in many what being emitted from the output phosphor, which results in what

A

Light photons
Increased image brightness

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11
Q

Expression of the ability of an image intensifier tube to increase the brightness of the image

A

Brightness gain
Or
Conversion factor

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12
Q

Brightness gain used to be found by multiplying what

A

Flux gain x minification gain

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13
Q

What maintains the overall appearance of the intensified image (contrast and brightness)

A

Automatic brightness control (ABC)

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14
Q

What automatically adjusts the kVp, mA, or both

A

ABC

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15
Q

ABC operates by monitoring what two things? (Image intensifier and output phosphor)

A

-Current though the image intensifier
- output phosphor intensity and adjusting the exposure factors if value falls below preset levels

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16
Q

(T/F) ABC can be slow to respond to changes in patient tissue thickness and density as it is moved

A

True

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17
Q

What results in increasing voltage to the electrostatic focusing lenses? What happens to the electron stream and the focal point?

A

Magnification mode
- the increase tightens the electron stream diameter
- focal point is shifted father from the output phosphor

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18
Q

What improves the ability to see small structures in fluoroscopy?
What is the con of using it?
What is it improving?

A

Magnification mode
Increases patient dose (not in digital tho)
Improves spatial resolution

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19
Q

Why does magnification mode increase patient dose?

A

fewer electrons are incident on the output phosphor, so the output intensity decreases, Need to increase the number of photons reaching the input phosphor

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20
Q

What is the misrepresentation of the true size or shape of an object

A

Image distortion

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21
Q

Unequal magnification of an image creates a ________ and loss of ______ around the ________

A
  • Pincushion appearance / vignetting
  • Brightness
  • Periphery
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22
Q

Image noise results when what is present to create the image?

A

Insufficient information

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23
Q

Too few X-rays exposing the input phosphor results in what?

A

Image noise

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24
Q

When not enough X-rays expose the input phosphor, what results with the light production?

A

Not enough light is produced
- decreases the number of electrons released by the photocathode

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25
Q

When decreased number of electrons is released by the photocathode what results with the output phosphor?

A

Fewer electrons interact with the output phosphor

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26
Q

Solution to fixing image noise in image intensification

A

Increasing mA

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27
Q

Two television cameras commonly used with image intensified viewing systems

A

Camera tube
Charge coupled device (CCD)

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28
Q

Early versions of digital fluoroscopy added what two things between the camera tube and monitor

A

Analog to digital converter (ADC)
Computer

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29
Q

In digital fluoro, replacing the camera tube with what along with the ADC improved digital fluoro?

A

With a charged coupled device (CCD)

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30
Q

CCD does what with light, noise, and spatial distortion?

A

More light sensitive
Exhibits less noise
No spatial distortion

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31
Q

Charge coupled device (CCD) does what to spatial resolution, radiation, and patient dose?

A

Higher spatial resolution
Less radiation
Reducing patient dose

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32
Q

In digital fluoro, what is used in place of an image intensifier?

A

Flat-panel detector

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33
Q

What is used for an indirect capture and direct capture detector

A

Indirect - Cesium iodide amorphous silicon (common)
Direct - Amorphous selenium

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34
Q

What is more lighter, more compact, and produces a digital signal directly, flat (panel detector or an image intensifier)

A

Flat-panel detector

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35
Q

When Bucky is built in and can’t be removed?
When the Bucky is able to be removed and handled by the tech

A

Direct capture
Indirect capture

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36
Q

Advantages of using flat panel detectors in place of an image intensifier

A
  • Reduced size (tower/bulk/weight)
  • replace spot filming and devices
  • don’t degrade with age
  • less artifacts
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37
Q

What has better contrast resolution, higher detective quantum efficiency (DQE), wider dynamic range
(Flat panel or image intensifier)

A

Flat panel detector

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38
Q

(T/F) image intensifier presents a rectangular field providing more information

A

False
Flat panel detector

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39
Q

Detective quantum efficiency (DQE) does what to patient dose

A

Decrease

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40
Q

(T/F) selecting kVp is the same as for general radiography

A

True

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41
Q

Collimation of the fluoroscopic beam does what to the field size exposing the patient?

A

Decreases

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42
Q

What allows for virtual collimation without exposing the patient

A

Last image hold (LIH)

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43
Q

What averages multiple frames together and what does it do to spatial resolution, patient dose, and image noise

A

Frame averaging
- decreases
- decreases
- decreases

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44
Q

(T/F) the option to include the grid in fluoro is a control setting

A

True

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45
Q

(T/F) modern fluoro units allow for the selection and interchangeability of added filtration thickness or material

A

True

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46
Q

Automatic exposure rate control (AERC) automatically adjusts what to maintain exposure to the flat panel detector

A

Adjusts tube current, voltage, filtration, and pulse width

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47
Q

Electronic magnification is the selection of what and it does what to patient dose?

A

Of a smaller field of view (FOV)
- no change to pt. Dose

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48
Q

What rapidly turns the X-ray beam on and off during a fluoro operation, and it’s effect on pt. dose?

A

Pulsed fluoroscopy
- decreases dose

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49
Q

Dose rate settings provide a control of what at the flat panel detector

A

Radiation dose
G/cm^2

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50
Q

What specifies the intensity of X-rays at a given point in air at a known distance from the focal spot or source of X-rays

A

Air KERMA
Kinetic energy released in matter

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51
Q

Air KERMA is measured in what

A

Gray

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52
Q

What are other dose displays that provide indicators of patient radiation risk and should be monitored in the patient’s record?

A

DAP and KAP

53
Q

Specialized equipment is used in imaging to do what two things?

A
  • improve visualization
  • provide important information about anatomic tissue
54
Q

interventional fluoroscopy uses what technology, and _____ ______ imaging such as cardiac imaging

A

bi-plane technology, rapid sequence (60 frames/ sec)

55
Q

what is digital subtraction?

A

when you can switch the whites into blacks on the image, and the opposite

56
Q

what is road mapping? What does it help with?

A

overlaying images as contrast moves
- navigating catheters or wires through veins

57
Q

Mobile X-ray units are categorized by the design of what and the types

A

generator
- direct power, battery power, capacitor-discharge, high-frequency

58
Q

What is typically used in the OR, and what capabilities does it have?

A

C-arm, fluoroscopic capabilities

59
Q

When using a C-arm what should be put close to the patient (above the patient) and why?

A

image intensifier
- lowers dose to the patient and everyone around

60
Q

when using fluoroscopy, pay particular attention to the distance between ____ and _____, and the total ________.

A
  • patient and x-ray tube
  • total fluoroscopy time
61
Q

What is used for feet, ankles, hands, and other small anatomy

A

mini c-arm

62
Q

What is a portable CT scanner, that also can provide both static and dynamic ranges along with 2D and 3D?

A

O-arm

63
Q

designed to image curved surfaces, like the mandible

A

panoramic x-ray
- most dentistry

64
Q

evaluates patients’ bone mineral density and mass for evidence of osteoporosis

A

bone densitometry

65
Q

the most common procedure with bone densitometry

A

dual-energy x-ray absorptiometry

66
Q

for bone densitometry, the lower spine and hips are scanned with two ______ x-ray energies to _______ bone from soft tissue

A

-different
-isolate

67
Q

what uses low kVp to image breast tissue having low subject contrast?

A

mammography
(24-34 kVp)

68
Q

breast is composed of soft tissues that attenuate the x-ray beam _____

A

similarly

69
Q

(T/F) mammographic X-ray tube is constructed of a different target material to produce more X-ray photons in the desired kVp range. What is the material commonly used?

A

True
- Molybdenum, rhodium, tungsten

70
Q

what grid is best for mammography

A

lower-ration grid with lower frequency

71
Q

the AEC for mammography must be more what and provide exposures to the IR

A

accurate in terms of reproducibility

72
Q

in mammography, why is compression used? (tissue, scatter, structures)

A
  • makes tissue thickness and optical density more uniform
  • reduces scatter
  • places structures closer to the IR
73
Q

when using magnification in mammography, what happens to patient dose, and why is it used?

A

increases dose
- used to visualize small structures

74
Q

Edison’s first fluoroscope was made with what type of screen that interacted with which beam?

A

calcium tungsten screen
interacted with the remnant beam

75
Q

when was the image intensifier introduced into the fluoroscopic system?

A

1950s

76
Q

the image intensifier did what two things?

A

-brightened the image
-allowed for indirect viewing of the image

77
Q

brief summary of what the image intensifier does

A

converts the remnant beam to light, then to electrons, then back to light, which increases the light intensity

78
Q

the 5 basic parts of the image intensifier

A

input phosphor, photocathode, electrostatic focusing lenses, accelerating anode, output phosphor

79
Q

what can be attached to the fluoroscopic unit to create permanent radiographic images?

A

spot film of cine (movie film)

80
Q

what is the input phosphor made of and where is it located in the tube?

A

cesium iodide, bonded to the curved surface of the intensifier tube

81
Q

the cesium iodide that a part of the input phosphor does what?

A

absorbs the remnant x-ray photon energy and emits light in response

82
Q

what is the photocathode made of and what do these materials do?

A

cesium and antimony compounds
- they emit electrons in response to light stimulus in a process called photoemission

83
Q

the photocathode is bonded to what?

A

directy to the input phosphor using a thin adhesive layer

84
Q

why are the input phosphor and the photocathode layers curved?

A

so that all of the electrons emitted from the photocathode travel the same distance to the output phosphor

85
Q

what are the negatively charged plates placed along the length of the image intensifier tube?

A

electrostatic focusing lenses

86
Q

what do the negatively charged plates (electrostatic focusing lenses) do?

A

repel the electron stream, focusing it toward the small output phosphor

87
Q

what sets the electron stream in motion at a constant velocity?
where is it placed?

A

accelerating anode
- located at the neck of the image intensifier near the output phosphor

88
Q

the accelerating anode maintains a constant potential of approx. what kV?

A

25 kV

89
Q

what is the output phosphor made of and what does it do?

A

made of silver-activated zinc cadmium sulfide
-absorbs electrons and emits light in response

90
Q

the light emitted from the input phosphor is proportional to the percentage of what?

A

x-ray absorption

91
Q

(T/F) the ratio of light to electron emission is one-to-one

A

false
-takes many light photons to result in the emission of one electron

92
Q

accelerating the electrons increases the light intensities at the output phosphor is called?

A

flux gain

93
Q

the reduction in the size of the output phosphor image compared with that of the input image also increases light intensities is called

A

minification gain

94
Q

how does minification gain make the image appear brighter?

A

because the same number of electrons is being concentrated on a smaller surface area

95
Q

(T/F) the ability of the image intensifier to increase brightness deteriorated with the age of the tube which means more radiation is necessary to produce the same level of output brightness

A

true

96
Q

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

A

charge-coupled device (CCD)

97
Q

the charge from the CCD is proportional to what and is stored in rows of what?

A
  • the light intensity
  • in rows of pixels
98
Q

to digitize the CCD, the _______ between each pixel (row gates), are charged in ______ moving the signal down the _____, where it’s transferred into the _____

A

electrodes
sequence
row
capacitors

99
Q

what is read out by the charge in each pixel?
what is read out by an electronic beam?

A

CCD
vidicon

100
Q

for the television monitor, the control grid forms the electrons into a beam that is controlled by the what and directed to the what?

A

focusing and deflecting coils
-fluorescent screen

101
Q

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

A

cassette spot film,

102
Q

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

A

film / photospot camera

103
Q

when the photospot camera spot-film exposure switch is pressed, the beam-splitting mirror is moved into place, which does what?

A

diverts some of the beam toward the photospot camera and exposes the film

104
Q

(T/F) the number of bits that the signal is divided into determines the contrast resolution (number of gray shades) for ADC

A

true

105
Q

what material makes the flat-panel detector possible?

A

amorphous silicon (photodetector)

106
Q

what are electronic components layered into glass substrate that include the readout, charge collector, and light-sensitive elements?

A

TFT array

107
Q

with flat-panel, the x-ray energy is absorbed by the _____ and converted into ____ energy, which is then absorbed by the photodetectors and converted to ______ charges, which are then captured and transmitted by the ________ to the monitor for display

A

scintillator
light
electric
TFT array

108
Q

what is used to minimize noise and amplify the signal from the active matric in flat-panel

A

ASIC - application-specific integrated circuits

109
Q

ASIC does what for noise, readout speed, and allows for what?

A

minimize
maximize
- allows for switching from low dose to high does inputs (static imaging)

110
Q

(T/F) flat-panel detectors also exhibit pincushion (vignetting) and S distortion artifacts

A

false

111
Q

flat-panel detector mA range

A

50-1200

112
Q

defines the exposure length of time during pulsed fluoro

A

pulse width

113
Q

ability to adjust the collimator without exposing the patient to additional radiation

A

virtual collimation

114
Q

digital subtraction techniques increase the visibility of vasculature by creating what 3 images?

A

precontrast, post-contrast, subtracted image

115
Q

what is the mask image that will be subtracted from the post-contrast image?

A

precontrast image

116
Q

the pre-contrast image results in an image with just the what?

A

contrast-filled vasculature

117
Q

(T/F) mobile units that are plugged into the wall may experience fluctuations in voltage, which affects the radiation output

A

true

118
Q

which x-ray generator needs to be plugged into the wall during operation?

A

capacitor discharge and high-frequency

119
Q

what primarily indicates fracture risk?
what may signify the need to evaluate the patient for secondary causes of osteoporosis?

A

T score
Z score

120
Q

aka 3D mammography

A

digital breast tomosynthesis (DBT)

121
Q

movement of the X-ray tube and IR in opposing directions to create images in a focal plane by blurring the anatomy located above and below the pane of interest

A

linear tomography

122
Q

(T/F) with linear tomography, the greater the amount of blurring above and below the more visible the area of interest

A

true

123
Q

what is directly related to the tomographic angle, and what is inversely related?

A

direct - amount of blur created
inverse - thickness of the section

124
Q

what is the fulcrum/pivot point and how can it be changed?

A

a fixed point that lines in the plane of interest
- the height of the fulcrum can be changed by moving the patient up/down (fixed) or the pivot point up/down (adjustable)

125
Q

what lies at the level of the fulcrum, and why are structures sharper?

A

focal/object plane
- objects above and below are blurred

126
Q

thickness or width of the focal plane is referred to as?
It’s determined by what and what is the relationship?

A

sections
- tomographic angle, inversely related

127
Q

the smaller the tomographic angle the greater the ________?

A

the thickness of the focal plane

128
Q

to achieve maximum blurring during tomography, the AOI should be _______ to the direction of movement

A

perpendicular

129
Q

to achieve the required blurring during tomography what must be increased?

A

exposure time

Rad105 (6 decks)

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