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DANB RHS Exam (new) > Chapters 5-6: Radiation Characteristics & Dental X-ray Image Characteristics > Flashcards

Chapters 5-6: Radiation Characteristics & Dental X-ray Image Characteristics Flashcards

1
Q

Define the term: amperage

A
  • the number of electrons that pass through a conductor
  • the strength of an electrical current
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2
Q

Define the term: ampere (A)

A

the unit of measure used to describe the number of electrons passing through a conductor * (electrical current strength)*

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3
Q

Define the term: angulation

A

the alignment of the central x-ray beam in the horizontal and vertical planes

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4
Q

Define the term: anode

A
  • the positive electrode in the x-ray tube
  • consists of a wafer-thin tungsten plate embedded in a solid copper rod
  • converts electrons into x-ray photons
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5
Q

Define the term: cathode

A
  • the negative electrode in the x-ray tube
  • consists of a tungsten wire filament in a molybdenum cup
  • supplies the electrons necessary to generate x-rays
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6
Q

Define the term: contrast

A
  • how sharply dark and light areas are differentiated or separated on an image
  • the difference in the degrees of blackness (densities) between adjacent areas on a dental image
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7
Q

Define the term: control panel

A

a part of the x-ray machine that contains an on/off switch and indicator light, an exposure button and indicator light, and control devices to regulate the x-ray beam

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8
Q

Define the term: density

A

the overall darkness or blackness of an image

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9
Q

Define the term: diagnostic image

A

a dental image that allows for the identifying and monitoring of diseases or injuries

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10
Q

Define the term: distortion

A
  • a geometric characteristic that refers to a variation in the true size and shape of the object being imaged
  • influenced by object-receptor alignment and the vertical angulation of the x-ray beam
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11
Q

Define the term: exposure

A

a measure of ionization produced in air by x-radiation or gamma radiation

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12
Q

Define the term: exposure factors

A

factors that influence the density of an image (ex: milliamperage, kilovoltage, exposure time)

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13
Q

Define the term: focal spot

A

the tungsten target of the anode that converts bombarding electrons into x-ray photons, concentrating the electrons and creating an enormous amount of heat

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14
Q

Define the term: half-value layer (HVL)

A

the thickness of material that, when placed in the path of the x-ray beam, reduces the exposure rate by one-half

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15
Q

Define the term: high contrast

A

a term describing an image with many very dark areas and very light areas and few shades of gray

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16
Q

Define the term: image receptor

A

a recording medium (ex: PSP plate, digital sensor)

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17
Q

Define the term: impulse

A

in dental imaging, a measure of exposure time

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18
Q

Define the term: intensity

A
  • the total energy of the x-ray beam
  • the product of the quantity (number of x-ray photons) and quality (energy of each photon) per unit of area per time of exposure
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19
Q

Define the term: inverse square law

A
  • a rule that states that “the intensity of radiation is inversely proportional to the square of the distance from the source of radiation”
  • as distance is increased, the radiation intensity at the object is decreased, and vice versa
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20
Q

Define the term: kilovoltage

A

in dental imaging, the x-ray tube peak voltage used during an exposure

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21
Q

Define the term: long-scale contrast

A
  • a term describing an image with many densities, or many shades of gray
  • results from the use of a higher kilovoltage range
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22
Q

Define the term: low contrast

A

a term describing an image with many shades of gray and few areas of black and white

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23
Q

Define the term: magnification

A
  • a geometric characteristic that refers to an image that appears larger than the actual size of the object it represents
  • influenced by target-receptor distance and object-receptor distance
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24
Q

Define the term: milliamperage

A

in dental imaging, the quantity (number) of x-ray emitted from the tubehead

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25
Q

Define the term: penumbra

A

the unsharpness or blurring of the edges of a structure viewed on a dental image

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26
Q

Define the term: quality of the x-ray beam

A
  • the mean energy or penetrating ability of the x-ray beam
  • controlled by the kilovoltage
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27
Q

Define the term: quantity of the x-ray beam

A
  • the number of x-rays produced in the dental x-ray unit
  • controlled by the milliamperage
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28
Q

Define the term: radiolucency

A

an area on a dental image appears radiolucent (dark/black) due to readily allowing the passage of the x-ray beam so that more x-rays reach the image receptor

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29
Q

Define the term: radiolucent

A

the portion of an image that is dark or black, due to the structure readily permitting the passage of the x-ray beam and allowing more x-rays to reach the image receptor

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30
Q

Define the term: radiopacity / radiodensity

A

an area on a dental image appearing radiopaque (light/white) due to resisting the passage of the x-ray beam and limiting the amount of x-rays that reach the image receptor

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31
Q

Define the term: radiopaque

A

the portion of an image that is light or white, due to the structure resisting the passage of the x-ray beam and limiting the amount of x-rays that reach the receptor

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32
Q

Define the term: scale of contrast

A

the range of useful densities on a dental images

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33
Q

Define the term: sharpness

A
  • refers to the capability of the image receptor to reproduce the distinct outlines of an object
  • influenced by focal spot size and movement
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34
Q

Define the term: stepwedge

A

a device constructed of uniform-layered thickness of an x-ray absorbing material (usually aluminum) used to demonstrate densities and contrast scales

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35
Q

Define the term: subject contrast

A

the characteristics of the subject (patient) that influence contrast, including the size and thickness of the patient

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36
Q

Define the term: subject thickness

A

the thickness of soft tissue and bone in a patient

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37
Q

Define the term: target-object distance

A

the distance from the source of x-rays (tungsten target in the anode) to the object being imaged (tooth)

38
Q

Define the term: target-surface distance

A

the distance from the source of x-rays (tungsten target in the anode) to the surface of the patient’s skin

39
Q

Define the term: tungsten target

A

a portion of the anode in the x-ray tube that serves as a focal spot and converts bombarding electrons into x-ray photons

40
Q

Define the term: volt (V)

A

the unit of measurement for voltage

41
Q

Define the term: voltage

A

in dental imaging, the measurement of force that refers to the potential difference between two electrical charges

42
Q

Define the term: wavelength

A
  • the distance between the crest of one wave and the crest of the next wave
  • determines the energy and penetrating power of the radiation
43
Q

Define the term: target-receptor distance

A

the distance from the source of radiation (tungsten target in the anode) to the image receptor

44
Q

What determines the energy and penetrating power of radiation?

A

wavelength

45
Q

What exposure setting controls the quality of the x-ray beam?

A

kilovoltage

46
Q

In order to create an x-ray beam with increased penetrating ability, how would you adjust the kilovoltage setting on the control panel?

A

increase the kilovoltage

47
Q

How does increased kilovoltage affect the density of the image?

A

increased density, which makes the image appear darker

48
Q

How does decreased kilovoltage affect the density of the image?

A

decreased density, which makes the image appear lighter

49
Q

How does increased kilovoltage affect the contrast of the image?

A

low contrast, which helps in the diagnosis of periodontal or periapical diseases

50
Q

How does decreased kilovoltage affect the contrast of the image?

A

high contrast, which helps in the diagnosis of caries

51
Q

How does increased exposure time affect the image?

A

the longer the exposure time, the more x-rays are delivered, which results in a darker image

52
Q

How many impulses occur in one second?

A

60

53
Q

If the kilovoltage setting is increased, how should you adjust the exposure time setting to achieve a diagnostic image?

A

decrease exposure time

54
Q

If the kilovoltage setting is decreased, how should you adjust the exposure time setting to achieve a diagnostic image?

A

increase exposure time

55
Q

What exposure setting determines the quantity of x-rays produced in the x-ray tubehead?

A

milliamperage

56
Q

What exposure setting controls and regulates the temperate of the cathode filament in the x-ray tubehead?

A

milliamperage

57
Q

How does increased milliamperage affect the density of the image?

A

decreased density, which makes the image appear darker

58
Q

How does decreased milliamperage affect the density of the image?

A

increased density, which makes the image appear lighter

59
Q

If the milliamperage setting is increased, how should the exposure time setting be adjusted to create a diagnostic image?

A

decreased exposure time

60
Q

If the milliamperage setting is decreased, how should the exposure time setting be adjusted to create a diagnostic image?

A

increased exposure time

61
Q

How does kilovoltage affect the intensity of the x-ray beam?

A

increased kilovoltage produces more energy and shorter wavelengths, which increases the intensity of the x-ray beam

62
Q

How does milliamperage affect the intensity of the x-ray beam?

A

increased milliamperage produce an x-ray beam with more energy, which increased the intensity of the x-ray beam

63
Q

How does exposure time affect the intensity of the x-ray beam?

A

longer exposure time produces more x-rays, which increases the intensity of the x-ray beam

64
Q

What are the three measurements used to describe the intensity of the x-ray beam?

A
  1. target-surface distance
  2. target-object distance
  3. target-receptor distance
65
Q

What is placed in the x-ray tubehead to reduce the intensity of the x-ray beam by removing the low-energy, longer-wavelength x-rays?

A

aluminum filters

66
Q

Does a higher half-value layer produce a more- or less-penetrating x-ray beam?

A

higher x-ray beam

67
Q

What are the two terms used to describe the black and white areas on an image?

A
  • radiopaque
    *radiolucent
68
Q

If a structure lacks density and allows the passage of more x-rays, how does the structure appear on an image?

A

radiolucent

69
Q

If a structure is dense and absorbs the x-rays passing through, how does the structure appear on and image?

A

radiopaque

70
Q

What are the two visual characteristics that determine the diagnostic quality of an image?

A
  • density
  • contrast
71
Q

How does increased subject thickness affect the density of the image?

A

the image appears more dense due to absorbing more of the x-ray beam

72
Q

What is the scale of contrast on an image with low kilovoltage settings?

A

short-scale contrast

73
Q

What is the scale of contrast on an image with high kilovoltage settings?

A

long-scale contrast

74
Q

What are the two terms used to describe the scale of contrast?

A
  • short-scale contrast
  • long-scale contrast
75
Q

Which scale of contrast is preferred in the diagnosis of caries, and why?

A
  • short-scale contrast
  • the carious lesion will appear more radiolucent, and the areas are easily distinguishable
76
Q

Which scale of contrast is preferred in the diagnosis of periodontal disease, and why?

A
  • long-scale contrast
  • the changes in bone loss as a result of periodontal disease will appear with many shades of gray
77
Q

What are the three geometric characteristics that affect the diagnostic quality of an image?

A
  • sharpness
  • magnification
  • distortion
78
Q

The detail, resolution, or definition of an image can also be described with what term?

A

sharpness

79
Q

What are the two factors that influence the sharpness of an image?

A
  • focal spot size
  • movement
80
Q

How does a small focal spot size influence the sharpness of an image?

A

sharper image

81
Q

How does a larger focal spot size influence the sharpness of an image?

A

loss of sharpness

82
Q

What are the two influencing factors of the magnification of an image?

A
  • target-receptor distance
  • object-receptor distance
83
Q

How does a longer target-receptor distance affect the magnification of an image?

A

decreased magnification

84
Q

How does a shorter target-receptor distance affect the magnification of an image?

A

increased magnification

85
Q

True or false: The tooth and the image receptor should always be positioned as close together as possible during exposure.

A

True

86
Q

How does increased object-receptor distance affect the magnification of an image?

A

increased magnification

87
Q

How does a decreased object-receptor distance affect the magnification of an image?

A

decreased magnification

88
Q

Forshortened and elongated images are a result of what geometric factor?

A

distortion

89
Q

What are the two influencing factors of distortion of an image?

A
  • object-receptor alignment
  • x-ray beam angulation
90
Q

How should the object being imaged and the image receptor be positioned to decrease distortion?

A

the object and image receptor should be parallel to each other

91
Q

How should the central ray of the x-ray beam be positioned in relation to the tooth and the image receptor to decrease distortion?

A

the central ray should be perpendicular to the tooth and the image receptor

DANB RHS Exam (new) (16 decks)

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