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1129 Final Review > Protection of Patient > Flashcards

Protection of Patient Flashcards

1
Q

What are common goals of all radiologic equiptment?

A
  • Optimize the quality of the image
  • reduce radiation exposure to patients
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2
Q

Who are protected when radiographic equipment is used safely?

A

Patients and all personnel

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3
Q

What are the two required features for every diagnostic imaging system?

A
  • protective tube housing
  • correctly functioning control panel
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4
Q

What other components of diagnostic systems have been designed to reduce patient dose?

A

Radiographic exam tables and other devices

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5
Q

What material is required of tube housing?

A

Needs to be lead lined

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6
Q

What does a lead-line tube housing protect patients and personnel from?

A

Off focus or leakage radiation

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7
Q

How do lead lined tube housing reduce off-focus and leakage radiation?

A

Restrict the emission of x-rays to the area of the primary beam

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8
Q

What are the leakage requirements for tube housing?

A

It needs to be constructed so that any leakage measured 1 m from the x-ray source does not exceed 0.88 mGy/hr

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9
Q

Where does a control panel/console need to be located?

A

Behind a suitable protective barrier

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10
Q

What are the features of the suitable protective barrier?

A

Has a radiation-absorbent window that permits observation of the patient during a procedure

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11
Q

What features are required of a control panel?

A

Must indicate the conditions of exposure and provide a positive indication when the tube is energized

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12
Q

How are exposure conditions represented on a console?

A

Through visible mA and kVp readouts

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13
Q

What happens on the console when the exposure begins?

A

A tone is emitted and then stops when it terminates

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14
Q

What does the audible sound indicate?

A

That the x-ray tube is energized and ionizing radiation is being emitted

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15
Q

What is the main feature of a radiographic examination table?

A

It needs to be strong enough to support patient whose weight is in excess of 400 lbs

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16
Q

What feature do exam table usually have?

A

A floating tabletop that makes it easier to maneuver a patient

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17
Q

What needs to remain uniform on an exam table?

A

Thickness

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18
Q

What is an important function of the material of a exam table?

A

Needs to be radiolucent so that it only absorbs a minimum amount of radiation

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19
Q

What material are exam tables usually made of?

A

Carbon fiber

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20
Q

What are two additional features of an exam table?

A

Have a grid and slot cover

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21
Q

What does the SID indicator provide?

A

A way to measure the distance from the anode focal spot is maintained

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22
Q

What are used to measure SID?

A

Lasers or tape measures

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23
Q

At what range are distance and centering indicator accurate?

A

Within 2% and 1% of the SID, respectively

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24
Q

What is a standard rule for the primary beam?

A

That it should be not larger than the size of the IR being used

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25
Q

What is light-localizing variable-aperture rectangular collimator used for?

A

Its used to adjust the size of the x-ray beam automatically or manually

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26
Q

What is the predominant x-ray beam limitation device?

A

Collimator

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27
Q

What is the purpose of a collimator?

A

To reduce scatter radiation

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28
Q

How are light-localizing variable-aperture rectangular collimators constructed?

A

With 2 sets of lead shutters, a light source and a mirror

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29
Q

What do the 1st shutter placed close to the window do?

A

Reduce off-focus radiation

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30
Q

What are the minimum skin sparing distance for fixed machines?

A

15 cm

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31
Q

What is the minimum skin sparing distance for mobile machines?

A

30 cm

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32
Q

What is luminance?

A

Brightness of the light source

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33
Q

What are the benefits of restricting x-ray field size to only include area of interest?

A
  • Significant Reduction in patient dose, because Less scatter is produced
  • Improves overall quality of the image
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34
Q

What is positive beam limitation?

A

When the beam of light is automatically adjusted to the size of the IR being used

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35
Q

What must the radiographer ensure when PBL is in use?

A

That the collimation is accurate and adjusted to the size of the part and no bigger than the IR

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36
Q

What are radiographic cones?

A

Circular metal tubes that attach to the x-ray tube housing and limit the beam to a predetermined size and shape

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37
Q

What are the two types of cones?

A

Flared metal tubes and straight cylinders

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38
Q

What types of cones are used in dental radiography?

A

Beam-defining cones

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39
Q

What is another type of beam limiting device?

A

Aperture diaphragm

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40
Q

What is an aperture diaphragm?

A

A flat piece of lead with a hole in it of a designated size and shape

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41
Q

Where is an aperture diaphragm placed?

A

Directly below the window of the x-ray tube to confine the primary beam to the given size of the hole

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42
Q

What do sizes of aperture diaphragms relate to?

A

Each size IR and SID

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43
Q

What is the purpose of beam filtration?

A

To remove low energy photons

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44
Q

How does beam filtration effect patient dose?

A

It lowers patient dose, by hardening the beam and making it more penetrating

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45
Q

How is the energy of the beam affected by filtration?

A

The effective energy of the beam is increased

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46
Q

What are the 3 types of filtration?

A
  • Inherent
  • Added
  • Total
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47
Q

How do beam filters work?

A

They absorb the low energy photons and permit high energy photons to pass through

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48
Q

What is the minimum total filtration required when more than 70 kVp is used?

A

2.5 mm Al equivalent

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49
Q

What is the minimum total filtration required when 50-70 kVp is used?

A

1.5 mm Al equivalent

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50
Q

What is the minimum total filtration required when less than 50 kVp is used?

A

0.5 Al equivalent

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51
Q

How is filtration most widely expressed?

A

In aluminum or its equivalent

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52
Q

What is the required Al eq for inherent filtration?

A

0.5 mm Al eq - glass and oil
1.0 mm Al eq - collimator mirrors

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53
Q

What is the required Al eq for added filtration?

A

1.0 Al (thin sheets of aluminum

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54
Q

What is the Al equivalent for total filtration?

A

2.5 Al eq

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55
Q

What is the minimum Al eq filtration for mobile diagnostic and fluoroscopic equipment?

A

2.5 mm Al eq

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56
Q

What is half value layer?

A

The thickness of a designated absorbed required to decrease the intensity of the primary beam by 50% of its initial value

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57
Q

Why must the HVL be measured?

A

To verify that the x-ray beam is adequately filtered

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58
Q

Who should obtain the HVL measurement?

A

A radiologic physicist

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59
Q

When should a radiologic physicist obtain the HVL?

A

At least once a year, after an x-ray tube is replaced or when the housing or collimator have been repaired

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60
Q

How is HVL expressed?

A

In millimeters of aluminum

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61
Q

What does HVL measure specifically?

A

Beam quality or effective energy of the x-ray beam

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62
Q

What is the range if minimum requireed HVL for kVp’s between 30-120?

A

From 0.3 to 3.2, with 70 kVp requiring 1.5 mm Al

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63
Q

What are compensating filters made up of?

A

Aluminum, lead acrylic or other suitable material

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64
Q

What are compensating filters used for?

A

To accomplish dose reduction and uniform imaging of body parts that vary considerably in thickness/tissue composition

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65
Q

How do compensating filters work?

A

They partially attenuate x-rays directed towards the thinner areas and allow more x-rays to strike the thicker areas

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66
Q

What are the two types of compensating filters?

A
  • wedge filter
  • trough, or bilateral wedge filter
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67
Q

What procedures are wedge filters usually used on?

A

Feet

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68
Q

What procedures are trough or bilateral wedge filters usually used on?

A

Chests

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69
Q

What are the two required radiation exposure characteristics?

A
  • exposure reproducibility
  • exposure linearity
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70
Q

What does exposure reproducibility provide?

A

Consistency in output radiation intensity for identical generator settings between individuals

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71
Q

What variance is accepted for exposure reproducibility?

A

A variance of 5% or less

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72
Q

How can reproducibility be verified?

A

By using the same technical exposure factors to make a series of repeated exposures and then observing with a calibrated ion chamber and seeing how the intensity varies

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73
Q

What does exposure linearity provide?

A

Consistency in output radiation intensity at selected kVp settings when generator settings are changed from on Mas and time combination to another

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74
Q

What is linearity?

A

The ratio of the differences in mSv/mAs or mR/mAs between two successive generator stations to the sum of these mSv/mAs or mR/mAs values

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75
Q

What does the linearity ratio need to be?

A

Less that 0.1

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76
Q

What is the variation percent when settings are changed from one mA to a neighboring mA station?

A

0.1

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77
Q

What is AEC?

A

An x-ray termination device that ends the radiation when a predetermined amount of radiation is received by an arrangement of sensors

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78
Q

What does AEC produce?

A

An acceptable image while limiting radiation exposure to a patient

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79
Q

What is a safety feature that is part of AEC?

A

A backup timer

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80
Q

What is phototiming?

A

Old terminology referring to photomultiplier tubes

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81
Q

What do today’s AEC systems utilize?

A

Ionization chambers

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82
Q

What is a radiographic grid?

A

A device made of parallel radiopaque strips alternately separated with low-attenuation strips of aluminum, plastic or wood

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83
Q

Where is a radiographic grid placed?

A

Between the patient and the IR

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84
Q

What do radiographic grids do?

A

Remove scattered x-ray photons that emerge from the patient before it can reach the IR and decrease image quality

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85
Q

What impact do radiographic grids have on image quality?

A

They increase radiographic contrast and visibility of detail

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86
Q

What size parts require the use of radiographic grids?

A

Parts that are 10 cm or more

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87
Q

Why does patient dose increase when using grids?

A

Because you need to adjust the exposure 2x for every 4cm over the average and the beam needs to be able to penetrate through the grid as well

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88
Q

What is grid ratio?

A

Refers to the height of the lead strips divided by the distance between each strip

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89
Q

What is the minimum SSD that should be used for mobile units?

A

Minimum SSD is at least 30 cm (12 inches)

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90
Q

What is the distance generally used for mobile radiography?

A

100 cm (40 inches) or 120 cm (48 inches)

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91
Q

What effect does SSD have on patient entrance exposure?

A

With increased SSD there is a more uniform distribution of exposure throughout the patient

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92
Q

When are mobile units used?

A

For patients who can’t be transported to a fixed unit

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93
Q

What are the 5 digital processed radiography imaging modes?

A
  • Computed tomography (CT)
  • Computed radiography (CR)
  • Digital radiography (DR)
  • Digital Fluoroscopy (DF)
  • Digital Mammography (DM)
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94
Q

What are negative features of conventional radiography: analog images?

A
  • Latent image creation and Latent imaging processing
  • Time consuming processing Time
  • Images often lost
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95
Q

What is a positive feature of conventional radiography: analog images?

A

Produced optimal-quality images

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96
Q

What has conventional radiography: analog images been replaced by?

A

Digital imaging

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97
Q

What is digital imaging?

A

Process of producing an electronic image

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98
Q

What are some limitations of digital imaging?

A

Inherent limitations with respect to spatial and contrast resolution due to dimensions of pixels

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99
Q

What is digital imaging subject to?

A

Artifacts because digital imaging are produced collectively by a matrix of elements and are subject to noise

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100
Q

How are images formed in digital imaging?

A

Latent image is formed by x-ray photons on a radiation detector

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101
Q

What is brightness in digital imaging?

A

The amount of luminance (light emission) on a display monitor

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102
Q

What are digital images composed of?

A

Numerical data that is stored in rows and columns called the image matrix

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103
Q

How does digital radiography work?

A

Image receptors convert energy into electric signals

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104
Q

What is a scintillator?

A

Converts x-ray energy into visible light and is made of amorphous silicone

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105
Q

What is visible light transformed into in digital radiography?

A

Transformed into electrical signals by charge-coupled devices (CCDs)

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106
Q

What is a photoconductor?

A

Converts x-ray energy directly into electrical signals which are then read by transistors.

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107
Q

What are photoconductors made of?

A

Amorphous selenium

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108
Q

Where can digital images be accessed?

A

At multiple workstations

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109
Q

What are the two types of conversion in digital imaging?

A

Indirect and direct conversion

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110
Q

What type of conversion does Scintillator use?

A

Indirect Conversion
- Scintillator > Photodiode > Thin-film transistor array > Electrical signals
- Scintillator > Charge-coupled device array > Electrical Signals

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111
Q

What type of conversion does Photoconductor use?

A

Direct conversion
- Photoconductor > Thin-film transistor array > Electrical signals

112
Q

How are images generated in computed radiography (CR)?

A

Using photostimulable luminescence (PSL)

113
Q

How is CR different than DR?

A

CR uses conventional radiographic equipment, traditional positioning and standard technical exposure factors

114
Q

What doe CR cassettes contain?

A

Photostimulable phosphors

115
Q

How are images read in CR?

A

A read unit scans the photostimulable phosphor plate with a laser beam and then displays it on a monitor

116
Q

Which type of radiography has a greater KV flexibility?

A

CR

117
Q

What type of radiography requires a more frequent use of grids?

A

CR since the imaging patients are more sensitive to scatter

118
Q

What are the advantages of DR?

A
  • lower doses
  • greater ease of use and faster patient throughput
  • immediate imaging results
  • additional image manipulation
  • Less overall maintenance
119
Q

What are the disadvantages of DR?

A
  • more costly
  • not cross compatible
  • single detector size
  • PSP imaging plates are subject to mechanical damage and chemical oxidation
  • high replacement costs
120
Q

What are the 3 types of artifacts DR are subject to?

A

Image aliasing, Moire patterns and contouring defects

121
Q

What is aliasing?

A

Distortion that shows up as jagged or saw-toothed lines

122
Q

What is More patterns?

A

A wavy looking pattern that is overlayed on an image

123
Q

What are contouring artifacts?

A

Patterns of small blocks on an otherwise smooth image

124
Q

How does DR eliminate the need for retakes?

A

Improper technical selections that produce contrast or brightness issues can be manipulated after image acquisition

125
Q

Why is there an increased repeat rate in DR?

A

Because of the ease of repeating images

126
Q

How are mispositioning repeats monitored?

A

An independent quality control technologist at a separate monitor

127
Q

Where does the body area need to be positioned on a CR IR?

A

In or near the center of the IR

128
Q

What are fluoroscopic procedures used for?

A

To capture dynamic or active motion images of selected anatomic structures

129
Q

Which type of radiography produces the greatest patient radiation exposure rate?

A

Fluoroscopic radiography

130
Q

How are fluoroscopic procedures performed?

A

With a fluoroscopic tube inside the xray table facing up toward the surface of the table

131
Q

What do non-digital fluoroscopic units use to amplify signals?

A

Image intensifier tube

132
Q

How does an image intensifier fluoroscopic unit work?

A

It converts the pattern of x-rays transmitted through the patient into a corresponding and amplified visible light pattern

133
Q

What are the benefits of image intensification fluoroscopy?

A
  • Increased image brightness
  • saving of Time for the radiologist
  • patient dose Reduction
134
Q

How is an image intensifier used?

A

It’s placed over the patient on this table during the examination and is used in conjunction with the tube

135
Q

How much is the brightness of the fluoroscopic image increased compared to non-image intensified fluoroscopy?

A

10,000 times

136
Q

How much mA is reduced when fluoroscopic vs intensified fluoroscopic?

A

Reduced from 3-5 mA to 1-1.5 mA

137
Q

What features are present in the vast majority of image intensifier tubes?

A

Magnification

138
Q

What is pulsed fluoroscopy?

A

Involves manual or automatic periodic activation of the tube rather than continuous activation

139
Q

What are the benefits of pulsed and interrupted fluoroscopy?

A
  • Significantly decreases patient dose
  • Extends tube life
  • Has a last-image hold feature
140
Q

What is the standard kVp range for adult patients using non-digital fluoroscopic imaging systems?

A

75-110 kVp

141
Q

What is the SSD for stationary fluoroscopes?

A

No less that 38 cm

142
Q

What is the SSD for mobile fluoroscope?

A

No less than 30 cm

143
Q

How should kVp be adjusted for children in non-digital fluoroscopic imaging systems?

A

KVp should be decreased as much as 25%

144
Q

In what ways are exposures limited for children using fluoroscoping imaging systems?

A

Decreasing technical factors, maintaining SSD and minimizing height of image intensifier entrance surface above patient

145
Q

What is the purpose of filtration in fluoroscopy?

A

To reduce patient skin absorbed dose from soft x-rays

146
Q

What is the HVL for non-digital fluoroscopic image systems?

A

HVL of 3-4.5 mm Al acceptable when kVp ranges from 80-100

147
Q

What is a cumulative timing device?

A

Measures the x-ray beam on time and sounds an alarm when the tube has been activated for 5 minutes

148
Q

Who sets up current standard limits for entrance skin exposure rates?

A

Federal government

149
Q

What is the maximum entrance skin exposure rate for non-digital fluoroscopic imaging systems?

A

Maximum of 88 mGya/min (10R/min)

150
Q

What is the maximum entrance skin exposure for fluoroscopic units equipped with high level control?

A

Maximum of 176 mGya/min (20 R/min)

151
Q

What is the primary protective barrier of non-digital fluoroscopic imaging systems?

A

2mm lead equivalent

152
Q

What type of exposure control switch does fluoroscopic machine need to have?

A

A dead man type

153
Q

What is the shape of a portable fluoroscopic unit?

A

C shaped with c-ray tube attached at one end and an image intensifier at the other

154
Q

What are portable fluoroscopic units used for?

A

In the operating room for orthopedic procedures, cardiac imaging and interventional procedures

155
Q

What risk do patients and personnel have with mobile fluoroscopic units?

A

Risk of large radiation doses from scatter

156
Q

What must C-arm equipment operate have?

A

Appropriate education and training to ensure they follow safety guidelines and meet safety protocols

157
Q

What is the source to end collimator distance required for mobile fluoroscopic units?

A

30 cm

158
Q

What should the distance be for image-intensifiers in mobile fluoroscopy units?

A

As short as possible to reduce entrance dose

159
Q

How should the C arm be positioned to reduce patient dose?

A

Under the patient since it limits scatter

160
Q

What happens when the C arm is positive over the patient?

A

Scatter becomes more intense and exposure increases correspondingly

161
Q

What system do digital fluoroscopy systems use for dose reduction?

A

Pulse progressive systems

162
Q

How does the pulse progressive system work?

A

Utilizes a brief high intensity pulse of radiation to create an entire image on the ouput phosphor, then the image is scanned to display on the screen and is brieftly deactivated which lowers patient dose

163
Q

What is last image hold?

A

The last image formed remains on the monitor so that no further radiation exposure is needed to regenerate it

164
Q

What are interventional procedures?

A

Locate high contrast using small objects such as catheters, stems or electrical leads

165
Q

What is digital subtraction angiography?

A

Visualization of blood vessels through the use of contrast materials

166
Q

How does DSA work?

A

A reference image is taken before contrast is injected and then subsequent images are taken with contrast which allows the differences between the two images to be emphasized

167
Q

What is roadmapping?

A

A static image of the vasculature may be obtained through subtraction, pre and post contrast injection

168
Q

Where is a catheter inserted?

A

Into vessels or tissues

169
Q

What is the purpose of a catheter?

A
  • Drainage
  • Biopsy
  • Alteration of vascular occlusions or malformation
170
Q

What is High-level-control fluoroscopy?

A

An operating mode for state of the art fluoroscopic equipment in which exposure rates are substantially higher than those normally allowed in routine procedures to see areas not usually seen in standard fluoro

171
Q

What has the FDA recommended for procedures involving fluoroscopic radiology?

A

That a notation be placed in their record if skin dose is in the range of 1-2 Gy received

172
Q

What are the procedures that involve extended fluoroscopic time?

A
  • percutaneous transluminal angioplasty
  • radio frequency cardiac catheter ablation
  • vascular embolozation
  • stent and filter placement
  • thrombocytes and fibrinolytic procedures
  • percutaneous trashepatic cholangiograpy
  • Endoscopic retrograde cholangiopancreatography
  • transjugular intrahepatic portosystemic shunt
  • percuraneous neprostomy
  • biliary Drainage
  • urinary or biliary stone removal
173
Q

What do non-radiologist physicians need when using fluoroscopic equipment?

A

Ongoing education and training

174
Q

What type of approach is essential during diagnostic x-ray procedures?

A

Holistic approach

175
Q

What does holistic care begin with the patient?

A

Effective communication between radiographers and patients

176
Q

What are the benefits of effective communication?

A
  • Alleviate the patient’s uneasiness
  • increases the likelihood of cooperation and successful completion of the imaging procedure
177
Q

How must radiographers limit patient’s exposure to ionizing radiation?

A
  • employ appropriate radiation Reduction techniques
  • use protective devices that minimize exposure
178
Q

What are the 9 ways patient exposure can be substantially reduced by?

A
  1. Effective communication
  2. Use of proper body or part immobilization
  3. Use of motion reduction techniques
  4. Use of appropriate beam limitation techniques
  5. Adequate filtration of the c-ray beam
  6. Use of specific area shielding
  7. Select suitable exposure factors in conjunction with computer-generated digital images
  8. Use of appropriate digital image processing
  9. Elimination of repeat radiographs
179
Q

When is communication between radiographers and patient effective?

A

When verbal and nonverbal messages are understood as intended

180
Q

What does effective communication encourage in patients?

A

Encourages a reduction in anxiety and emotional stress

181
Q

What does effective communication enhance?

A

The professional image of the radiographer as a person who cares about patient well being

182
Q

What does effective communication increase the chances of?

A

Successful completion of the the x-ray exam

183
Q

What must the radiographer do if a procedure will case pain, discomfort or strange sensations?

A

Inform the patient of all before the procedure begins without overemphasizing them

184
Q

What is a result of poor communication with a patient?

A

The need to do a repeat radiograph because of inadequate or misinterpreted instructions

185
Q

What should patient protection begin with during a diagnostic x-ray?

A

Begins with clear, concise instructions

186
Q

Why is there a need for immobilization in imaging?

A

To prevent the patient from moving during the image which will create blur

187
Q

What are the consequences of blurred image?

A
  • exams need to be repeated
  • results in additional radiation exposure
188
Q

How can patient motion be eliminated or minimized?

A
  • proper body or part immobilization
  • use of motion Reduction techniques
189
Q

What are the two types of patient motion?

A

Voluntary and involuntary

190
Q

What type of motion does adequate immobilization during exams help reduce?

A

Voluntary motion

191
Q

Why is shielding needed?

A

To prevent radiation exposure to radio sensitive body organs

192
Q

Which areas of the body should be shielded whenever possible?

A
  • lens of eye
  • breasts
  • Reproductive organs
  • thyroid glands
193
Q

What is the first step in gonadal shielding?

A

Collimating

194
Q

What types of shields are used for the eyes?

A

Contact type shields that are positioned directly on the patient

195
Q

How much more exposure do female reproductive organs involving the pelvis receive than males?

A

3 times

196
Q

How much exposure is reduced in females by a 1mm lead flat contact shield?

A

50% reduction

197
Q

How much is exposure reduced in males with a 1mm lead contact shield?

A

90-95%

198
Q

Where must gonadal shielding be placed to provide protection?

A

Directly over the patient’s reproductive organs

199
Q

What should be used to guide placement of testicular or ovarian shields?

A

External landmarks

200
Q

In male patients in supine position what can be used to guide shield placement over the testes?

A

The pubic symphysis

201
Q

In female patients what should be used to guide shield placement of the ovaries?

A

Shield should be placed approximately 2.5medial to each ASIS

202
Q

What are the types of gonadal shields?

A
  • Flat contact shields
  • shadow shields
  • shaped contact shields
  • clear lead shields
203
Q

What are flat contact shields?

A

An uncontoured, flat lead shield that is placed over the patients gonads

204
Q

What is a shadow shield?

A

A suspended shield that is placed above the beam defining system that casts a shadow on the patient directly over their gonads

205
Q

What is a lead filter?

A

A type of shadow shield that has breast and gonadal shielding plates and casts a shadow on the patient

206
Q

What are shaped contact shields?

A

Cuplike shields that may be held in place with a suitable carrier

207
Q

What are the benefits of specific area shielding?

A
  • minimize the number of potential deleterious c-ray induced mutations expressed in future generations
  • reduces exposure to specific areas that are shielded
208
Q

Why is the selection of appropriate technical factors essential in diagnostic imaging?

A

It ensures patients only receive a minimal dose of

209
Q

What should high quality images have?

A
  • sufficient brightness to display anatomic structures
  • appropriate levels of subject contrast to differentiate anatomic structures
  • maximum spatial resolution
  • minimal distortion
210
Q

What are the 7 considerations for technical exposure factor?

A
  1. Mass per unit volume of tissue of the area of interest
  2. Effective atomic number and electron density of tissues involved
  3. Type of image receptors
  4. SID
  5. Type and quantity of filtration
  6. Type of X-ray generator used
  7. Balance of radiographic density or brightness and contrast required
211
Q

When AEC is not used what should be used to ensure uniform selection of technical exposure factors?

A

Technique charts

212
Q

What is a radiographer responsible for checking before imaging?

A

The technique chart and taking the patients condition into account

213
Q

What combination of kVp and mas reduces patient dose?

A

Use of higher kVp and lower mAs

214
Q

What does the use of high kVp and low mas result in?

A

A high energy, penetrating beam and a small,, patient dose

215
Q

What does the use of low kVp and high MAs result in?

A

A low energy x-ray beam in which the majority will be absorbed by the patient

216
Q

What is correct image post processing essential to in imaging?

A

Essential to produce a high quality image in which artifacts produced by the IR, software or patient are controlled

217
Q

What does a quality control program include?

A

Regular monitoring and maintenance of processing and imaging display equipment

218
Q

What does a quality control program mandate?

A

Full acceptance of new equipment, regular calibration and performance evaluations of existing machines and proactive and consistent image review

219
Q

What is the air gap technique?

A

An alternate to using a grid to reduce scatter in that the patients is placed using an OID of 4-6 inches and an SID of 10-12 feet

220
Q

At what kVp levels are air gap techniques more useful?

A

When less than 90 kVp is used

221
Q

At what kVp are air gap techniques successful in chest X-rays?

A

120-140 kvp

222
Q

How does the air gap technique work?

A

Many of the scattered X-rays are so low in energy that they are absorbed by the air before they reach the IR

223
Q

Why does the SID need to be increased so much in the air gap technique?

A

To counteract the magnification that is caused by the increased OID

224
Q

How does patient dose using air gap compare to tabletop and grid?

A

It’s higher in air gap compared to tabletop but lower than grid

225
Q

What are the consequences of repeat images?

A

Additionally exposure to the patient, specifically a double dose

226
Q

What type of repeat images should be eliminated?

A

Repeats resulting from the carelessness or poor judgment of the radiographer

227
Q

When is the only time an additional image is permissible?

A

When it’s recommended by the radiologist for the purpose of obtaining additional diagnostic info

228
Q

At what rate have repeat images increased?

A

Approximately 5% but can be as high as 17%

229
Q

What are the main reasons for repeat images?

A

Positioning errors and ease of repeating

230
Q

What are the benefits of a repeat analysis program?

A

Helps identify the number of repeats and reasons for producing unacceptable images with the hopes of improving

231
Q

What are the reasons for unaccepatable images?

A

Patient mispositioning
Incorrect centering of the beam
Patient motion during the exposure
Incorrect collimation
Presence of external foreign bodies
Postprocessing artifacts

232
Q

What are examples of unecessary radiologic procedures?

A

A chest x-ray examination automatically scheduled on admission to the hospital.
• A chest x-ray examination as part of a preemployment physical.
• Lumbar spine examinations as part of a preemployment physical.
• Chest x-ray examination or other unjustified x-ray examination as part of a routine health checkup.
• Chest x-ray examination for mass screening for tuberculosis (TB).
• Whole-body computed tomography (CT) screening.

233
Q

What are the 3 ways the amount of radiation received can be presented?

A

Entrance Skin Exposure
Bone Marrow Dose
Gonadal Dose

234
Q

Which measure of radiation received is the most reported?

A

Entrance skin exposure

235
Q

How is ESE meansured?

A

Using thermoluminescent dosimeters to measure skin dose direcrly

236
Q

Which measures of radiation received can only be estimated?

A

Bone marrow and gonadal dose

237
Q

What is used to measure the impact of gonadal dose?

A

Genetically significant dose (GSD)

238
Q

What is the estimated GSD for US?

A

0.20 mSv

239
Q

What is fluoroscopic guided positions?

A

Practice of using fluoroscopt to determine the exact location of the central ray before taking an exposure

240
Q

What is the ASRT’s position ong FGP?

A

That its an unethical process and should never be used in place of appropriate positioning pre-exposure

241
Q

The pro’s of FGP are?

A

Its faster than having a repeat exposure
Reduces the number of repeat exposures
Provides less radiation exposure to the patient

242
Q

What is the position of the ACR on abdominal radiologic exams of female patients?

A

That they don’t need to be postponed or selectively schedules as long as full consideration of the clinical status of the patient is complete

243
Q

How should radiographers determine the possibility of pregnancy?

A

Ask the date of the LMP or order a pregnancy test before the pelvis is irradiated

244
Q

What are the details needed to fill out a request for radiation dose form for unknown pregnancies that were irradiated?

A
245
Q
A

The x-ray unit or units used for the study
• The projections taken
• The number of images associated with each examination
• Each projection’s technical exposure factors (kVp, mAs, image receptor size)
• The source-to-image receptor distance (SID) for each projection
• The patient’s anteroposterior (AP) or lateral dimensions at the site of each projection
• For fluoroscopic irradiation, the approximate kVp, mA, and especially the duration
• For spot images, the number taken, the kVp and mA selected, and the approximate exposure time

246
Q

What is the NCRP’s position on risk of fetal exposure with regard to termination of pregnancy?

A

Risk is considered negligible with doses less than 5 cGy and exposure to the fetus by itself wouldn’t be a reason to terminate

247
Q

Who is resposible for reviewing and measuring the absorbed Eqd of a fetus?

A

RSO

248
Q

What special efforts should be taken to minimize dose of known pregnant patients?

A

Restrictively selecting exposure factors to produce the smallest exposure needed for a useful image and precisely collimating

249
Q

What shields should be used when imaging known pregnant people?

A

Lead apron or other contact shields that wrap around the whole body

250
Q

What radiation effects are children more vulnerable to?

A

Both late somatic effects and genetic effects

251
Q

How should childrens dose be adjusted when compared with adults?

A

Doses need to be made smalled and protection methods need to be used in force

252
Q

How can moption be reduced for pediatric patients?

A

Using short exposure times and effective immobilization

253
Q

How can cooperation be gained with pediatric patients?

A

By using specially designed rooms with appropriate restraining devices, providing suitable entertainment devices and using shielding

254
Q

What factors can increase dose in children?

A

Repeats due to motion, improper shielding or insufficient collimation

255
Q

What is the image gently campaign?

A

To raise awareness about methods for lowering patient dose suring pediatric imaging exams

256
Q

What is the image wisely campaign?

A

To lowe the amount of radiation used in medically necessary procedures

257
Q

Which modality is considered a high radiation exposure examination?

A

Computed Tomography (CT)

258
Q

What are patients who receive CT at a higher risk of?

A

Increased associated cancer risk

259
Q

What are the two concerns that relate to patient dose in CT scanning?

A

Skin dose and dose distribution

260
Q

Why are skin doses smaller in CT than in diagnostic imaging?

A

They use smalled field sizes and use smaller images

261
Q

How is dose distribution different in CT versus radiography?

A

Dose is more uniformly distributed since the tube rotates around the patient

262
Q

Why is direct patient shileding not typically used in CT?

A

Because of the rotational nature of exposure and the tight collimation of the beam

263
Q

What is a spiral scan pitch ratio?

A

Ratio of the movement or advance of the patient couch during a CT scan to the x-ray beam collimator dimensions

264
Q

How is patient dose related to higher pitch?

A

Patient dose is reduced because the numer of x-rays produced during each rotation is spread out

265
Q

How is patient dose related to lower pitch?

A

Patient dose is increased

266
Q

How is patient dose optimized in CT?

A

Tube current modulation (longitudinal or angular), Iterative reconstruction, optimization of tube voltage and scan parameters and correct patient centering

267
Q

How is tube current modulation used to reduce patient dose?

A

mA varies along the longitudinal access and a lower tube current is used for thinner anatomy and higher tube current for thicker anatomy

268
Q

How is iterative reconstruction used to reduce patient dose?

A

CT scan data can be reconstructed, modified and reconstructed again until the image has the lowest noise possible, which allows lower doses to be used

269
Q

How is tube voltage optimization used to reduce patient dose?

A

Increasing voltage lowers patient dose, while all other factors increase it

270
Q

How is patient centering used to reduce patient dose?

A

Miscentering a patient by 2cm can lead to an increase dose of 25%, so positioning properly ensures that dose is kept low and magnification doesn’t apply

271
Q

What are relevant dose parameters for CT?

A

CTDI (computed tomography dose index)
CTDI weighted
CTDI volume
Effective mAs
Dose length product

272
Q

What is CTDI?

A

A measurement of ionization that’s obtained through the use of a phantom inserted into an ionization chamber which is then irradiated to represent localized dose

273
Q

What is CTDI weighted?

A

The average of two CTDI values, one from the pencil chamber in the middle of the phantom and the other in the periphery of the phantom

274
Q

What is CTDI volume?

A

Average absorbed dose within the scanned volume

275
Q

What is DLP?

A

The produce of CTDI volumen and irradiated scan length

276
Q

What is MDCT scanning?

A

Multidetector computed tomography

277
Q

What are the advanctages of MDCT?

A

Shorter scan durations, improved contrast-enhanced scans, longer scan ranges permitting CT, better use in trauma applications, thinner sections near isotropic imaging

1129 Final Review (6 decks)

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