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DANB RHS Exam > Radiation Basics (Ch 1-5) > Flashcards

Radiation Basics (Ch 1-5) Flashcards

Ch 1- Radiation History Ch 2- Radiation Physics Ch 3- Radiation Characteristics Ch 4- Radiation Biology Ch 5- Radiation Protection

1
Q

What is the purpose of the control panel on the x-ray machine?

A

contains an on/off switch and indicator light, an exposure button and indicator light, and control devices (time, kilovoltage and milliamperage selectors) to regulate the x-ray beam

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2
Q

What is the purpose of the extension arm on the x-ray machine?

A

to suspend and allow for movement and positioning of the tubehead and house the electrical wires that extend from the control panel to the tubehead

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3
Q

What is the x-ray tubehead?

A

a tightly sealed, heavy metal housing that contains the x-ray tube that produces x-rays; includes the metal housing, insulating oil, tubehead seal, x-ray tube, transformers, aluminum discs, lead collimator, and the position-indicating device

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4
Q

Define the term: absorption

A

the total transfer of energy from the x-ray photon to the atom of matter through which the x-ray beam passes

(Absorption depends on the energy of the x-ray beam and the composition of the absorbing matter or tissue)

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5
Q

What is the ALARA concept?

A

a concept of radiation protection that states that all exposure to radiation must be kept to a minimum, or “as low as reasonably achieveable”

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6
Q

Define the term: alpha particles

A

a type of particulate radiation emitted from the nuclei of heavy metals; contain two protons and two neutrons are are positively charged

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7
Q

What are aluminum discs and what are they used for?

A

discs or sheets of aluminum, usually 0.5mm thick, that are placed in the path of x-ray beam to filter out the nonpenetrating, longer-wavelength x-rays

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8
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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9
Q

What is an 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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10
Q

What is the anode?

A

the positive electrode in the x-ray tube that consists of a wafer-thin tungsten plate embedded in a solid copper rod and converts electrons into x-ray photons

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11
Q

Define the term: atom

A

a tiny, invisible particle that is the fundamental unit of matter

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12
Q

Define the term: neutral atom

A

an atom that contains an equal number of protons and electrons

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13
Q

What is the autotransformer and what is it’s purpose?

A

a voltage compensator that corrects for minor fluctuations in the current flowing through the x-ray machine

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14
Q

What is the beam alignment device and what is it’s purpose?

A

a device used to align the position-indicating device in relation to tooth and receptor that positions the intraoral receptor in the mouth and retains the receptor in position during exposure; helps stabilize the receptor in the mouth and reduce the chance of movement, thus reducing the patient’s exposure to x-radiation

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15
Q

Define the term: beta particles

A

fast-moving electrons emitted from the nucleus of radioactive atoms

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16
Q

What is the cathode and what is it’s purpose?

A

the negative electrode in the x-ray tube that consists of a tungsten wire filament in a molybdenum cup; supplies the electrons necessary to generate x-rays

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17
Q

Define the term: cathode ray

A

a stream of high-speed electrons that originates from the cathode in an x-ray tube

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18
Q

What is a cell?

A

the basic structural unit of living organisms

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19
Q

Define the term: cell differentiation

A

individual characteristics of a cell that determine the response of the cell to radiation exposure

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20
Q

Define the term: cell metabolism

A

the physical and chemical processes of a cell that determine the response of the cell to radation exposure

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21
Q

What is a circuit?

A

a path of electrical current

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22
Q

What is the filament current/low-voltage circuit and what setting is it controlled by?

A

the circuit that regulates the flow of electrical current to the filament of the x-ray tube; controlled by the milliampere settings

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23
Q

What is the high-voltage circuit and what setting is it controlled by?

A

the circuit that provides the high voltage required to accelerate electrons and to generate x-rays in the x-ray tube; controlled by the kilovoltage settings

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24
Q

Define the term: coherent scatter/unmodified scatter

A

one of the interactions of x-radiation with matter in which the path of a low-energy x-ray photon interacts with an outer-shell electron; no change in the atom occurs and an x-ray photon of scattered radiation is produced

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25
Q

What is collimation?

A

the restriction of the size and shape of the x-ray beam in order to reduce patient exposure

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26
Q

What is the collimator/collimating device and what is it’s purpose?

A

a diaphragm, usually made of lead, used to restrict the size and shape of the x-ray beam

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27
Q

Define the term: compton electron

A

an outer-shell electron that is ejected from the its orbit during Compton scatter; carries a negative charge

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28
Q

What is Compton scatter?

A

one of the interactions of x-radiation with matter in which the x-ray photon collides with a loosely bound, outer-shell electron and gives up part of its energy and continues in a different direction at a lower energy level

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29
Q

Define the term: contrast

A

how sharply dark and light areas are differentiated on an image; the difference in the degrees of densities between adjacent areas on a dental radiograph

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30
Q

What are the control devices on an x-ray machine?

A

the components of the control panel of the x-ray machine that regulate the x-ray beam, including the timer, kilovoltage an milliamperage selectors

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31
Q

What is the control panel?

A

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

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32
Q

What is the copper stem and what is it’s purpose?

A

a portion of the anode that dissipates heat away from the tungsten target

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33
Q

Define the term: coulomb (C)

A

a unit of electrical charge; the quantity of electrical charge transferred by 1 ampere in 1 second

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34
Q

What is a critical organ and what are some examples?

A

an organ that, if damaged, diminishes the quality of an individual’s life (skin, thyroid gland, lens of the eye, bone marrow)

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35
Q

What are cumulative effects of radiation?

A

the additive effects of repeated radiation exposure

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36
Q

What is an alternating current (AC)?

A

a current in which electrons flow in opposite directions

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37
Q

What is a direct current (DC)?

A

a current in which electrons flow in one direction

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38
Q

Define the term: density

A

the overall darkness of an image

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39
Q

What is the direct theory of radiation?

A

a theory that suggest that cell damage results when ionizing radiation hits critical areas directly within the cell

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40
Q

Define the term: dose

A

the amount of energy absorbed by tissue

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41
Q

Define the term: total dose

A

the quantity of radiation received or the total amount of radiation energy absorbed

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42
Q

What is dose equivalent used for?

A

a measurement used to compare the biologic effects of different types of radiation

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43
Q

Define the term: dose rate

A

the rate at which exposure radiation occurs and absorption takes place (dose rate = dose/time)

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44
Q

What is the dose-response curve?

A

a curve that can be used to correlate the “response,” or damage of tissues with the “dose,” or amount of radiation received

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45
Q

Define the term: electrical current

A

the flow of electrons through a conductor used to produce x-rays

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46
Q

Define the term: electricity

A

the energy used as a source of power to make x-rays

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47
Q

Define the term: electromagnetic radiation

A

propagation of wavelike energy (without mass) through space or matter

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48
Q

Define the term: electron

A

a tiny negatively charged particle found outside of the nucleus in the atom

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49
Q

Define the term: energy

A

what occurs when matter is altered

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50
Q

What is exposure a measure of?

A

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

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51
Q

What is exposure time?

A

the interval during which x-rays are produced

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52
Q

What is the extension arm?

A

a part of the dental x-ray machine that suspends the x-ray tubehead and houses the electrical wires that extend from the control panel to the tubehead

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53
Q

What is a radiation film badge and what is it’s purpose?

A

a device used to measure and monitor radiation exposure; worn by persons frequently exposed to radiation

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54
Q

What is filtration?

A

the use of absorbing materials (aluminum) for removing the low-energy x-rays from the primary beam

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55
Q

What is added filtration?

A

aluminum discs inserted into the x-ray tubehead seal and collimator to absorb low-energy x-rays

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56
Q

What is inherent filtration?

A

occurs when the primary beam passes through the glass window of the x-ray tube, the insulating oil, and the tubehead seal

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57
Q

What is total filtration?

A

the combination of the inherent filtration and added filtration in an x-ray machine

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58
Q

Define the term: frequency

A

the number of wavelengths that pass a given point in a certain amount of time and indicates the energy of radiation

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59
Q

What are genetic cells and what are some examples?

A

cells that contain genes; reproductive cells (ova, sperm)

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60
Q

What are genetic effects of radiation?

A

effects of radiation that are not seen in the person irradiated but are passed on to future generations through genetic cells

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61
Q

Define the term: gray (Gy)

A

the unit for measuring absorbed dose

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62
Q

What is half-value layer (HVL)?

A

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

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63
Q

Define the term: impulse

A

a measure of exposure time (60 impulses occur in 1 second)

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64
Q

What is the indirect theory of radiation?

A

a theory suggesting that cell damage results from x-ray photons being absorbed with the cell, causing the formation of toxins, which, in turn, damage the cell

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65
Q

What is the insulating oil?

A

oil that surrounds the x-ray tube and transformers inside the tubehead

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66
Q

Define the term: ion

A

an electrically unbalanced particle; an atom that gains or loses an electron

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67
Q

Define the term: ionizing radiation

A

radiation that is capable of producing ions by removing or adding an electron to an atom; classified into two groups: particulate radiation and electromagnetic radiation

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68
Q

Define the term: kilovolt (kV)

A

the unit of measurement for voltage

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69
Q

Define the term: kilovoltage

A

in radiography, the x-ray tube peak voltage used during an exposure; measured in kilovolts

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70
Q

Define the term: kilovoltage peak (kVp)

A

the maximum voltage that is used during an x-ray exposure

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71
Q

Define the term: kinetic energy

A

energy of motion

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72
Q

What is a lead apron and what is it’s purpose?

A

a flexible lead shield used to protect the patient’s reproductive and blood-forming tissues from scatter radiation

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73
Q

What is the lead collimator and what is it’s purpose?

A

a lead diaphragm or tubular device used to restrict the size and shape of the x-ray beam

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74
Q

What is the leaded-glass housing and what is it’s purpose?

A

leaded-glass vacuum tube that prevents x-rays from escaping in all directions

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75
Q

What are the long-term effects of radiation?

A

effects of radiation that appear years, decades, or generations after exposure and are associated with small amounts of radiation absorbed repeatedly over a long period

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76
Q

Define the term: mass

A

weight; the physical volume or bulk of a solid body

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77
Q

Define the term: matter

A

anything that occupies space and has mass

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78
Q

What is the maximum accumulated dose (MAD)?

A

the maximum accumulated lifetime radiation dose that may be received by persons who are occupationally exposed to radiation

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79
Q

What is the maximum permissible dose (MPD)?

A

maximum dose equivalent that a body is permitted to receive in a specific period with little to no injury

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80
Q

What is the metal housing?

A

the metal body of the dental x-ray tubehead that surrounds the x-ray tube and transformers

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81
Q

Define the term: milliamperage

A

in radiography, the quantity of x-rays emitted from the tubehead; measured in milliamperes

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82
Q

Define the term: milliampere (mA)

A

a unit of measurement used to describe the intensity of an electrical current (1/1000 of an ampere)

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83
Q

What is a milliampere-second (mAs)?

A

a unit of radiographic exposure equal to the product of milliamperage and exposure time

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84
Q

Define the term: mitotic activity

A

the process of cell division that determines the response of a cell to radiation exposure

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85
Q

What is the molybdenum cup and what is it’s purpose?

A

a portion of the cathode in the x-ray tube that focuses electrons into a narrow beam and directs the beam across the tube toward the tungsten target in the anode

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86
Q

What is a nanometer?

A

a measurement used for wavelength

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87
Q

Define the term: neutral atom

A

an atom that contains an equal number of protons and electrons

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88
Q

Define the term: neutron

A

an electrically neutral or uncharged particle

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89
Q

Define the term: nucleon

A

part of an atomic nucleus (protons, neutrons)

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90
Q

Define the term: nucleus

A

the central, positively charged core of an atom, composed of protons and neutrons

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91
Q

Define the term: particulate radiations

A

tiny particles of matter that possess mass and travel in straight lines at high speeds

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92
Q

What is the period of injury of radiation?

A

occurs after the latent period following exposure to radiation and can include a variety of cellular injuries

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93
Q

What is the photoelectric effect?

A

one of the interactions of x-radiation with matter, where the x-ray photon collides with a tightly bound, inner-shell electron and gives up all its energy to eject the electron from its orbit

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94
Q

Define the term: photon

A

a bundle of energy with no mass or weight that travels as a wave at the speed of light and moves through space in a straight line

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95
Q

What is the position-indication device (PID) and what is it’s purpose?

A

an open-ended, lead-lined cylinder extending from the opening of the metal housing of the tubehead, used to aim and shape the beam

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96
Q

What is a protective barrier and what is an example?

A

a barrier of radiation-absorbing material used to protect the operator from the primary and scatter radiation (a wall)

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97
Q

Define the term: proton

A

a positively charged particle with a mass of 1

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98
Q

What is the quality of an x-ray beam and what is it controlled by?

A

the mean energy or penetrating ability of the x-ray beam that is controlled by the kilovoltage

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99
Q

What is quality factor (QF)?

A

a factor used for radiation protection purposes that accounts for the exposure effects of different types of radiation (QF = 1)

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100
Q

What is the quantity of an x-ray beam and what is it controlled by?

A

the number of x-rays produced in a the dental x-ray unit and is controlled by milliamperage

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101
Q

Define the term: radiation

A

a form of energy carried by waves or a stream of particles

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102
Q

What is background radiation and what are some examples?

A

a form of ionizing radiation that ubiquitous in the environment (cosmic and terrestrial radiation)

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103
Q

What is characteristic radiation?

A

a form of radiation that occurs when a high-speed electron dislodges from an inner-shell electron from an atom, causing ionization of the atom

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104
Q

What is electromagnetic radiation and what are some examples?

A

the propagation of wavelike energy through space or matter, accompanied by electric and magnetic fields (cosmic rays, gamma rays, x-rays, ultraviolet rays, visible light, infrared light, radar waves, microwaves, radio waves)

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105
Q

What is general radiation/bremstrahlung/braking radiation?

A

a form of radiation that occurs when speeding electrons slow down because of their interactions with the tungsten target in the anode

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106
Q

What is ionizing radiation?

A

radiation capable of producing ions (particulate or electromagnetic radiation)

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107
Q

What is the primary radiation/primary beam/useful beam?

A

the penetrating x-ray beam produced at the target of the anode and the exits the tubehead

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108
Q

Define the term: radiation leakage

A

any radiation, with the exception of the primary beam, that is emitted from the dental tubehead

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109
Q

Define the term: particulate radiation

A

tiny particles of matter that possess mass and travel in straight lines at high speeds (electrons, protons, neutrons)

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110
Q

Define the term: scatter radiation

A

a form of secondary radiation the results from an x-ray beam that has been deflected from its path by the interaction with matter

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111
Q

Define the term: secondary radiation

A

radiation created when the primary beam interacts with matter; less penetrating that primary radiation

112
Q

What is radiation absorbed dose (rad)?

A

a unit for measuring absorbed dose; the traditional unit of dose equivalent to the gray (Gy)

113
Q

Define the term: radiation biology

A

the study of the effects of ionizing radiation on living tissues

114
Q

Define the term: radioactivity

A

the process by which certain unstable atoms or elements undergo spontaneous disintegration or decay, in an effort to attain a more balanced nuclear state

115
Q

Define the term: radiograph

A

a two-dimensional representation of a three-dimensional object

116
Q

Who is a dental radiographer?

A

any person who positions, exposes, and processes dental x-ray image receptors

117
Q

Define the term: radiography

A

the art and science of making radiographs by the exposure of film to x-rays

118
Q

Define the term: radiology

A

the science or study of radiation as used in medicine, dealing with the use of x-rays, radioactive substances, and other forms of radiant energy in the diagnosis and treatment of disease

119
Q

What is a radioresistant cell and what are some examples?

A

a cell that is resistant to radiation (bone, muscle, nerve cells)

120
Q

Define the term: rectification

A

the conversion of alternating current to direct current

121
Q

Define the term: risk

A

the likelihood of adverse effects or death resulting from an exposure to a hazard

122
Q

Define the term: Roentgen (R)

A

the traditional unit of exposure for x-rays

123
Q

What is the Roentgen equivalent in man (rem)?

A

the traditional unit of the dose equivalent; the product of absorbed dose (rad) and a quality factor (QF) specific for the type of radiation

124
Q

What are short-term effects of radiation?

A

effects of radiation that appear within minutes, days, or weeks and are associated with large amounts of radiation absorbed in a short time

125
Q

Define the term: Sievert (Sv)

A

a unit of measurement equivalent to the rem

126
Q

Define the term: somatic cells

A

all the cells in the body, with the exception of the reproductive cells

127
Q

What are somatic effects of radiation and what are some examples?

A

radiation injuries that produce changes in somatic cells and produce poor health in the irradiated individual (cancer, leukemia, cataracts)

128
Q

What are stochastic effects of radiation?

A

biologic effects from radiation that occur as a direct function of dose; the probability of occurrence increases with increasing absorbed dose, however, the severity of effects does not depend on the magnitude of absorbed dose

129
Q

What is thermionic emission?

A

the release of electrons from the tungsten filament when the electrical current passes through it and heats the filament

130
Q

What is the thyroid collar and what is it’s purpose?

A

a flexible lead shield used to protect the thyroid from scatter radiation

131
Q

What is a transformer?

A

a device used to increase or decrease the voltage of incoming electricity

132
Q

What is the step-down transformer?

A

a device used to decrease the incoming voltage from 110 or 220 volts to the low voltage required (usually 3 to 5 volts)

133
Q

What is the step- up transformer?

A

a device used to increase the incoming line voltage from 110 or 220 volts to the high voltage required (usually 65,000 to 100,000 volts)

134
Q

What is the tubehead?

A

the tightly sealed metal housing that contains the dental x-ray tube; includes the metal housing, insulating oil, tubehead seal, x-ray tube, transformers, aluminum discs, lead collimator, and position-indicating device; also contains a filament used to produce electrons and a target used to produce x-rays

135
Q

What is the tubehead seal and what is it’s purpose?

A

the aluminum or leaded-glass covering of the tubehead that permits the exit of x-rays from the tubehead, seals the oil in the tubehead, and filters the x-ray beam

136
Q

What is the tungsten filament?

A

a coiled wire of tungsten in the cathode in the x-ray tube that produces electrons when heated

137
Q

What is the 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

138
Q

Define the term: velocity

A

speed; in dental radiography, the speed of a wave

139
Q

Define the term: volt (V)

A

unit of measure for voltage

140
Q

Define the term: voltage

A

the measurement of force that refers to the potential difference between two electrical charges

141
Q

Define the term: wavelength

A

the distance between the crest of one wave to the crest of the next wave; determines the energy and penetrating power of the radiation

142
Q

Define the term: x-radiation

A

a high-energy radiation produced by the collusion of a beam of electrons with a metal target in an x-ray tube

143
Q

Define the term: x-rays

A

a beam of energy that has the power to penetrate substances and record image shadows on photographic film or digital sensors

144
Q

What is the x-ray tube?

A

a component part of the x-ray tubehead that generate x-rays, including a leaded-glass vacuum tube, cathode, and anode

145
Q

What occurs when matter is altered?

A

energy

146
Q

What are the two ways that molecules can be formed?

A

1) by the transfer of electrons
2) by the sharing of electrons between the outermost shells of atoms

147
Q

In dentistry, is radiation or radioactivity used?

A

radiation

148
Q

What are the two categories of ionizing radiation?

A

1) particulate radiation
2) electromagnetic radiation

149
Q

What is the difference in energy between particulate radiation and electromagnetic radiation?

A

In particulate radiation, energy travels in straight lines at high speed. In electromagnetic radiation, energy travels in waves

150
Q

What are the two classifications of electrons?

A

1) beta particles
2) cathode rays

151
Q

What are some examples of electromagnetic radiation?

A

cosmic rays, gamma rays, x-rays, ultraviolet rays, visible light, infrared light, radar waves, microwaves, and radio waves

152
Q

What are the two concepts of electromagnetic radiation?

A

1) wave concept
2) particle concept

153
Q

What is the difference between velocity, wavelength, and frequency in electromagnetic radiation?

A

1) velocity measures the speed of the wave
2) wavelength measures the distance between the crest of one wave and another
3) frequency measures the number of wavelengths

154
Q

Frequency and wavelength are inversely related, which means that if the frequency of the wave is high, then the wavelength will be ____

A

short

155
Q

What are the two different measurable energies of electromagnetic radiation?

A

frequencies and wavelengths

156
Q

From the following particles, which originates in the x-ray tube?
Alpha particles, beta particles, cathode rays, protons, or neutrons?

A

cathode rays

157
Q

What is the appearance of x-rays?

A

X-rays are invisible and cannot be detected by any of the senses

158
Q

What is the mass of x-rays?

A

X-rays have no mass or weight

159
Q

What is the charge of x-rays?

A

X-rays have no charge

160
Q

What is the speed of x-rays?

A

X-rays travel at the speed of light

161
Q

What is the wavelength property of x-rays?

A

X-rays travel in waves and have short wavelengths with a high frequency

162
Q

What is the path of travel for x-rays?

A

X-rays travel in straight lines and can be deflected/scattered

163
Q

What is the focusing capability of x-rays?

A

X-rays cannot be focused to a point and always diverge from a point

164
Q

What is the penetrating power of x-rays?

A

X-rays can penetrate liquids, solids, and gases. the composition of the substance determines whether x-rays penetrate or pass through or are absorbed

165
Q

What is the absorption property of x-rays?

A

X-rays are absorbed by matter; the absorption depends on the atomic structure of matter and the wavelength of the x-ray

166
Q

What is the fluorescence capability of x-rays?

A

X-rays can cause certain substances to fluoresce or emit radiation in longer wavelengths (visible light or ultraviolet light)

167
Q

What is the x-rays effect on film?

A

X-rays can produce an image on film

168
Q

What is x-rays effect on living tissues?

A

X-rays cause biologic changes in living cells

169
Q

What is considered the “heart” of the x-ray generating system?

A

the x-ray tube

170
Q

What are the two components of the cathode in the x-ray tube?

A

1) tungsten filament
2) molybdenum cup

171
Q

What are the two components of the anode in the x-ray tube?

A

1) tungsten target
2) copper stem

172
Q

Is the cathode in the x-ray tube a positive or negative electrode?

A

negative

173
Q

Is the anode in the x-ray tube a positive or negative electrode?

A

positive

174
Q

What component of the x-ray tube supplies the electrons needed to produce x-rays?

A

cathode

175
Q

What component of the x-ray tube converts electrons into x-ray photons?

A

anode

176
Q

In the cathode, the ____ produces electrons when heated, and the _____ focuses those electrons into a narrow beam and directs that beam toward the ______ in the anode.

A

tungsten filament, molybdenum cup, tungsten target

177
Q

What are the two classifications of electrical current?

A

1) direct current (DC)
2) alternating current (AC)

178
Q

What is the difference between direct electrical currents and alternating electrical currents?

A

Direct current occurs when the electrons flow in one direction; alternating current occurs when the electrons flow in two, opposite directions

179
Q

Rectification is the conversion of alternating to direct electrical currents. However, what acts as a self-rectifier in dental radiology?

A

the x-ray tube

180
Q

What control setting would be adjusted to increase or decrease the number of electrons passing through the cathode?

A

milliampereage (mA)

181
Q

What control setting would be adjusted to increase or decrease the current passing from the cathode to the anode?

A

kilovoltage peak (kVp)

182
Q

What are the two types of electrical circuits used in the production of x-rays?

A

1) low-voltage/filament circuit
2) high-voltage circuit

183
Q

How many volts are used in a low-voltage/filament circuit?

A

3-5 volts

184
Q

How many volts are used in a high-voltage circuit?

A

65,000-100,000 volts

185
Q

Which type of circuit is controlled by the milliampere settings?

A

low-voltage/filament circuit

186
Q

Which type of circuit is controlled by the kilovoltage settings?

A

high-voltage

187
Q

In the production of dental x-rays, what are the three types of transformers used to adjust the electrical circuits?

A

1) step-down transformer
2) step-up transformer
3) autotransformer

188
Q

A step-down transformer is used to decrease the incoming voltage from 110- or 220-line voltage to the __ -___ volts used by the filament circuit.

A

3-5 volts

189
Q

A step-up transformer is used to increase the incoming voltage from 110- to 220-line voltage to the ___-___volts used by the high-voltage circuit.

A

65,000-100,000 volts

190
Q

What occurs when the electrons are released from the tungsten filament and the electrical current passes through it and heats the filament?

A

thermionic emission

191
Q

What part of the x-ray tube is the first to be activated when the exposure button is pushed?

A

the high-voltage circuit

192
Q

When the electrons strike the tungsten target, creating kinetic energy, how much of that energy is converted to x-rays, and how much is lost as heat?

A

Less than 1% is converted to x-rays, the remaining 99% is lost as heat

193
Q

What part of the x-ray tube filters out the longer wavelengths x-rays from the beam?

A

the aluminum disks

194
Q

What are the two mechanisms of radiation that the kinetic energy of the electrons is converted to x-ray photons?

A

1) general/braking radiation (bremsstrahlung)
2) characteristic radiation

195
Q

Approximately how much of the x-ray energy produced at the anode is classified as general/braking radiation?

A

70%

196
Q

Is general/braking radiation or characteristic radiation most common in dental x-rays?

A

general/braking radiation

197
Q

What are the three classifications of x-radiation?

A

1) primary radiation
2) secondary radiation
3) scatter radiation

198
Q

Which type of x-radiation is more penetrating?
Primary radiation or secondary radiation

A

primary radiation

199
Q

Once x-rays exit the tubehead and arrive at the patient, what are the three events that can occur with that patient?

A

1) x-rays can pass through the patient without any interaction
2) x-ray photons can be completely absorbed by the patient
3) x-ray photons can be scattered

200
Q

What are the four possibilities that can occur when an x-ray photon interacts with matter?

A

1) no interaction
2) absorption or photoelectric effect
3) Compton scatter
4) coherent scatter

201
Q

What percent of the interactions with matter from the dental x-ray beam accounts for the photoelectric effect?

A

30%

202
Q

What type of x-radiation effect occurs mostly from scatter radiation?

A

Compton scatter

203
Q

What percent of the interactions with matter from the dental x-ray beam accounts for Compton scatter?

A

62%

204
Q

What percent of the interactions with matter from the dental x-ray beam accounts for coherent scatter?

A

8%

205
Q

When voltage is increased, the speed of electrons is _____; then the electrons strike the target with greater force and energy, resulting in a penetrating x-ray beam with a ___ wavelength.

A

increased; short

206
Q

A ___ kilovoltage should be used when the area to be examined is dense or thick.

A

higher

207
Q

Increasing ____ results in a higher energy x-ray beam with increased penetrating ability.

A

kilovoltage peak (kVp)

208
Q

How is density affected by increasing only the kilovoltage peak settings?

A

the image appears darker from an increased density

209
Q

How is density affected by decreasing only the kilovoltage peak settings?

A

the image appears lighter from a decreased density

210
Q

How is contrast affected by increasing only the kilovoltage peak settings?

A

the image has low contrast, meaning many shades of gray, instead of black and white

211
Q

How is contrast affected by decreasing only the kilovoltage peak settings?

A

the image has high contrast, meaning many black and white areas and few shades of gray

212
Q

What type of contrast is preferred for the detection of caries?

A

high contrast

213
Q

What type of contrast is preferred for the detection of periodontal or periapical disease?

A

low contrast

214
Q

When kilovoltage peak is increased by 15, exposure time should be decreased by ___.

A

half

215
Q

When kilovoltage peak is decreased by 15, exposure time should be ___.

A

doubled

216
Q

Why should the milliamperage setting not exceed 15 mA?

A

because of the excessive heat produced in the x-ray tube as a result

217
Q

Kilovoltage peak controls ___ and milliamperage controls ____

A

kilovoltage = quality/wavelength/penetrating ability of the x-ray beam
milliamperage = quantity/the number of x-rays produced

218
Q

An increase in the number of electrons that strike the anode ____ the number of x-rays emitted from the x-ray tube.

A

increased

219
Q

What two settings have a direct influence on the number of electrons produced by the cathode filament?

A

milliamperes and exposure time

220
Q

When milliamperage is increased, exposure time must be ____.

A

decreased

221
Q

When milliamperage is decreased, exposure time must be ___.

A

increased

222
Q

How is density affected by increasing only the milliamperage settings?

A

the image appears darker from an increased density

223
Q

How is density affected by decreasing only the milliamperage settings?

A

the image appears lighter from a decreased density

224
Q

The quality and quantity of x-rays are described together using what term?

A

intensity

225
Q

Higher kilovoltage levels ____ the intensity of the x-ray beam.

A

increase

226
Q

Higher milliamperage levels ___ the intensity of the x-ray beam.

A

increase

227
Q

An increase in exposure time ____ the intensity of the x-ray beam.

A

increases

228
Q

What is target-surface distance?

A

the distance from the source of radiation to the patient’s skin

229
Q

What is target-object distance?

A

the distance from the source of radiation to the tooth

230
Q

What is target-receptor distance?

A

the distance from the source of radiation to the receptor

231
Q

When x-rays travel away from their source of origin, does the intensity of the beam increase or decrease?

A

decrease

232
Q

Is an x-ray beam more intense when it is exiting from an 8-inch position-indicating device or a 16-inch?

A

8-inch

233
Q

What is used to:
-reduce the intensity of the x-ray beam
-remove the low-energy, less penetrating, longer-wavelength x-rays
-increase the mean penetrating capability of the x-ray beam

A

aluminum filters

234
Q

Is all ionizing radiation harmful?

A

yes

235
Q

Does all ionizing radiation produce biologic changes in living tissue?

A

yes

236
Q

When x-rays are absorbed by patient’s tissue, what are the two possible mechanisms of radiation injury?

A
  • ionization
    -free radical formation
237
Q

What are the two theories of radiation injury?

A

-direct theory
-indirect theory

238
Q

Which theory of radiation injury is more likely to occur and why?

A

indirect theory, because of the high water content of cells

239
Q

Can radiation damage occur from dental x-rays?

A

Yes, although the radiation doses are extremely low

240
Q

What are the two types of biologic effects of radiation?

A

-stochasitc
-nonstochastic

241
Q

What are some examples of stochastic effects of radiation?

A

cancer/tumors, genetic mutations

242
Q

What are some examples of nonstochastic effects of radiation?

A

erythema, loss of hair, cataract formation, decreased fertility

243
Q

Which type of biologic effect of radiation requires larger radiation doses in order to cause serious health impairments?

A

nonstochastic effects

244
Q

Following radiation exposure, what are the next three periods of radiation injury?

A

-latent period
-period of injury
-recovery period

245
Q

How is the latent period of radiation injury affected by increased radiation dose?

A

the latent period is shorter

246
Q

How is the latent period of radiation injury affected by decreased radiation dose?

A

the latent period is longer

247
Q

Are all cellular radiation injuries permanent?

A

no

248
Q

List the 5 factors that determine the degree of radiation injury

A

-total dose of radiation
-dose rate
-amount of tissue irradiated
-cell sensitivity
-age

249
Q

Are children or adults more susceptible to radiation damage?

A

children

250
Q

What type of radiation effects are seen within minutes, days or weeks after exposure?

A

short-term effects

251
Q

What type of radiation effects are seen after years, decades or generations after exposure?

A

long-term effects

252
Q

Which type of radiation effects are not seen in dentistry?

A

short-term effects

253
Q

What are the two classifications of cells in the human body?

A

-somatic
-genetic

254
Q

Which type of biologic effect of radiation cannot be passed on to future generations?

A

somatic effects

255
Q

Which type of biologic effect of radiation does not effect the person irradiated, but instead is passed on to future generations?

A

genetic effects

256
Q

List some examples of radiosensitive cells

A

-small lymphocyte
-bone marrow
-reproductive cells
-intestinal mucosa
-skin
-lens of the eye
-oral mucosa

257
Q

List some examples of radioresistant cells.

A

-muscle tissue
-nerve tissue
-mature bone/cartilage
-salivary gland
-thyroid gland
-kidney
-liver

258
Q

List some examples of critical organs that are affected by dental radiographs.

A

-skin
-thyroid gland
-lens of the eye
-bone marrow

259
Q

What are the three factors that determine the response of a cell to radiation exposure?

A

-miotic activity
-cell differentiation
-cell metabolism

260
Q

What are the three units of measurement in radiation?

A

-exposure
-dose
-dose equivilant

261
Q

What are the two systems used to define radiation measurements, and which is the system used in current dental radiology?

A

-Traditional/Standard System
-SI System/International System of Units

The SI System is currently used

262
Q

What are the three units of radiation measurement in the SI System?

A

-Coulombs/kilogram (C/kg)
-Gray (Gy)
-Sievert (Sv)

263
Q

What are the three units of radiation measurement in the Traditional/Standard System?

A

-Roentgen (R)
-Radiation absorbed dose (rad)
-Roentgen equivalent (in) man (rem)

264
Q

What is the exposure measurement of radiation for the Traditional/Standard System and the SI System?

A

-Traditional/Standard System = roentgen (R)
-SI System = coulomb (C)

265
Q

What is the dose measurement of radiation for the Traditional/Standard System and the SI System?

A

-Traditional/Standard System = radiation absorbed dose (rad)
-SI System = gray (Gy)

266
Q

What is the dose equivilent measurement of radiation for the Traditional/Standard System and the SI System?

A

-Traditional/Standard System = roentgen equivalent (in) man (rem)
-SI System = sievert (Sv)

267
Q

What is the estimated potential risk of dental radiography inducing a fatal cancer in an individual?

A

approximately 3 in 1 million

268
Q

Who is the person responsible for prescribing dental radiographs?

A

the dentist

269
Q

What are the two organizations responsible for the dental radiograph procedures?

A

-American Dental Association (ADA)
-U.S. Food and Drug Administration (FDA)

270
Q

What are the two basic types of position indicating devices currently used?

A

-rectangular
-round

271
Q

Why is a conical-shaped position indicating device no longer used?

A

the pointed cone shape caused the x-rays to penetrate the plastic and produce scatter radiation

272
Q

Which type of position indicating device is most effective in reducing a patient’s exposure to radiation?

A

rectangular shaped

273
Q

During radiation exposure, what must the dental radiographer avoid most to ensure the highest level of operator protection?

A

the primary beam

274
Q

What is the most effective way a dental radiographer can limit x-radiation exposure?

A

maintaining a distance of at least 6 feet from the x-ray tubehead during exposure

275
Q

To avoid the primary beam during exposure, how should the dental radiographer position themself in relation to the primary beam?

A

perpendicular to the beam

276
Q

If the patient is having a hard time staying still during the x-ray exposure, should the dental radiographer hold the sensor in place for the patient?

A

no

277
Q

What organization dictates the maximum permissible dose that an individual can receive?

A

National Council on Radiation Protection and Measurements (NCRP)

DANB RHS Exam (9 decks)

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