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1102 Rad > Final Exam > Flashcards

Final Exam Flashcards

1
Q

What is radiolucent?

A

The portion of a processed image that is dark or black

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2
Q

What is an example of someone that appears radiolucent? Why?

A

caries appear radiolucent, caries are less dense than surrounding structures

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3
Q

How does radiopaque appear?

A

It is the portion of a processed image that appears light or white

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4
Q

What is an example of something that appears radiopaque? Why?

A

metallic restorations appear radiopaque: Because they are very dense and absorb radiation

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5
Q

What are the two types of bones in the human body?

A

cortical or cancellous

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6
Q

What is another term for cortical bone?

A

compact bone

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7
Q

What is cortical bone?

A

the dense outer layer of bone

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8
Q

How does cortical bone appear on x-ray

A

radiopaque

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9
Q

What is a cancellous bone?

A

Soft spongy bone between two layers of dense cortical bone

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10
Q

What is a cancellous bone composed of?

A

Numerous bony trabeculae ( lattice shaped spaces filled with bone marrow)

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11
Q

Is cancellous bone radiopaque or radiolucent?

A

Mostly radiolucent

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12
Q

What is trabeculae?

A

Denser boney pieces, that are radiopaque

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13
Q

Is bone marrow Radiolucent or radiopaque?

A

Radiolucent

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14
Q

Is the inferior border of the mandible composed of cortical or cancellous bone?

A

cortical

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15
Q

What is this a picture of?

A

Cortical (Compact Bone)

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16
Q

What is this a picture of?

A

Cancellous bone

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17
Q

What is this a picture of?

A

Trabeculae (cancellous bone)

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18
Q

What is this a picture of and what is it? What is an Example?

A

Process- Obvious prominence or projection of bone
ex. coronoid process of mandible

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19
Q

What is this a picture of and what is it? What is an example?

A

Ridge- Linear prominence or projection
Ex. External oblique ridge

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20
Q

What is this a picture of and what is it? What is an example?

A

Spine- Sharp, thorn-like projection
ex. anterior nasal spine of maxilla

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21
Q

What is this a picture of and what is it? What is an example?

A

Tuberosity- Rounded prominence of bone
ex. maxillary tuberosity

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22
Q

What is this a picture of and what is it? What is an example?

A

Canal- tubelike passageway through bone for nerves, blood vessels
ex, mandibular canal

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23
Q

What is this a picture of and what is it? What is an example?

A

Foramen- Opening or hole in bone, nerves, blood vessels pass through
eg. mental foramen

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24
Q

What is this a picture of and what is it? What is an example?

A

Fossa- broad, shallow, depression of bone
ex. submandibular fossa

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25
Q

What is this a picture of and what is it? What is an example?

A

Sinus- Hollow space, cavity recess in bone
ex. maxillary sinus

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26
Q

What is this a picture of and what is it? What is an example?

A

Septum: A bony wall or partition that divides two spaces or cavities

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27
Q

Is the septum radiolucent or radiopaque?

A

radiopaque

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28
Q

Where may the septum be present?

A

within the space of fossa or sinus

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29
Q

What is this a picture of and what is it? What is an example?

A

Suture: An immovable joint representing a line of union between adjoining bones
ex. median palatal suture

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30
Q

Do sutures appear as radiolucent or radiopaque?

A

Thin radiolucent lines

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31
Q

What is this a picture of?

A

Incisive forman

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32
Q

What is this a picture of?

A

Superior foramina of incisive canal

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33
Q

What is this a picture of? What is it?

A

Canine Fossa (Lateral Fossa)
smooth depressed area, medial to infraorbital foramen between canines and lateral incisors

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34
Q

What is this a picture of? What is it?

A

Nasal Cavity (Nasal Fossa) Pear shaped compartment superior to the maxilla

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35
Q

What is this a picture of?

A

Floor of the nasal cavity

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36
Q

What is this a picture of? What is it?

A

Inferior nasal conchae: wafer thing curves plates of bone on lower lateral walls of nasal cavity

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37
Q

Is the maxillary sinus radiolucent or radiopaque above the apices of premolars and molars?

A

radiolucent

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38
Q

Is the maxillary sinus radiolucent or radiopaque at the line of the maxillary sinus floor?

A

radiopaque

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39
Q

Why is it important to get a good dental image of the maxillary sinuses when considering implants?

A

To determine the amount of bone to see if an impant can be placed with out hitting the sinus

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40
Q

What is this a picture of? What is it?

A

Nutrient canals in maxillary sinus: Tiny, tubelike passages in max sinus contains nerved and blood vessels to teeth and interdental areas

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41
Q

What is this a picture of? What is it?

A

Inverted Y: Lateral wall of nasal fossa and anterior border of max sinus meet above max canine

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42
Q

What is this a picture of?

A

Maxillary tuberosity

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43
Q

What is this a picture of? What is it?

A

Hamulus: Small hook-like projection of bone from medial pterygoid plate of sphenoid bone posterior to maxillary tuberosity

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44
Q

What is this a picture of? What is it?

A

Zygomatic Process- Bony projection on max that articulates with zygomatic bone

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45
Q

What is this a picture of?

A

Zygoma

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46
Q

What is the largest and strongest bone of the face?

A

the mandible

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47
Q

What is this a picture of? What is it?

A

Ramus: Vertical portion found posterior to the third molar

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48
Q

What is this a picture of? What is it?

A

Body of mandible : Horizontal U shaped portion from ramus to ramus

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49
Q

What is this a picture of? What is it?

A

Alveolar Process: Encases and supports the teeth

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50
Q

What is this a picture of and what is it? What is an example?

A

Tubercle- Small bump or nodule of bone
ex. genial tubercles of mandible

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51
Q

What is this a picture of?

A

Lingual Foramen

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52
Q

What is this a picture of?

A

Mental Ridge

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53
Q

What is this a picture of?

A

Mental Fossa

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54
Q

What is this a picture of?

A

Mandibular Canal

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55
Q

What is this a picture of?

A

Mylohyoid Ridge

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56
Q

What is this a picture of?

A

External oblique Ridge

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57
Q

What is this a picture of?

A

Submandibular Fossa

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58
Q

What is this a picture of? What is it?

A

Coronoid Process: Bony prominence on anterior ramus of mandible attachment for a muscle of mastication

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59
Q

What is this a picture of?

A

Alveolar crest

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60
Q

What is the alveolar crest made of?

A

dense cortical bone

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61
Q

How does the alveolar crest appear on radiographs?

A

radiopaque

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62
Q

What is this a picture of?

A

Lamina Dura

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63
Q

What is this a picture of? What is it?

A

Periondtal ligamnet space: space between the tooth and lamina dura

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64
Q

How is the periodontal ligament space seen?

A

continuous thin radiolucent line around the tooth

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65
Q

How does anterior alveolar bone look?

A

dense radiopaque line caries in density and shape

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66
Q

How does posterior alveolar bone look?

A

appears less dense, flatter and smoother in inter-proximal areas
less radiopaque than anterior regions

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67
Q

What is this a picture of?

A

Incisive foramen

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68
Q

Which of the following structures is the most radiolucent?
a. pulp
b. cementum
c. dentin
d. enamel

A

a. pulp

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69
Q

Chpt 1:
What is radiation?

A

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

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70
Q

What is X-Radiation?

A

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

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71
Q

What is radiology?

A

the science or study of radiation within medicine

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72
Q

what is an x-ray?

A

a beam of energy that has the power to penetrate substances and record image shadows on receptors

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73
Q

What is a radiograph?

A

an image or picture produced on a receptor by exposure to ionizing radiation: its a 2D representation of a 3D object

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74
Q

What is radiography?

A

The art and science of making radiographs by the exposure of a receptor to x-rays

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75
Q

Who discovered x-rays?

A

Wilhelm Conrad Roentgen ( pronounced “ ren-ken”)

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76
Q

When did roentgen discover x-rays?

A

1895

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77
Q

How did roentgen discover x-rays?

A

He was experimenting with cathode rays. Using vacuum tubes, and electrical current and special screen covered with a material that glowed when exposed. He found that a cathode ray tube emitted invisible rays that could penetrate paper and wood

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78
Q

Why did roentgen call them x-rays?

A

X because of the unknown

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79
Q

Chpt 2
What is matter?

A

Anything that occupies space and has mass

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80
Q

What happens when matter is altered?

A

energy results

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81
Q

What is an atom?

A

Fundamental unit of matter: all matter is composed of atoms

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82
Q

What two parts make up an atom?

A
  1. the central nucleus
  2. the orbiting electrons
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83
Q

How is the identity of an atom determined?

A

By the composition of the nucleus and the arrangements of electrons

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84
Q

What is the nucleus composed of?

A

Protons and neutrons

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85
Q

What charge do protons have?

A

Positive

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86
Q

What charge do neutrons have?

A

They carry no electrical charge

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87
Q

What does the number of protons and neutrons inside the nucleus determine?

A

The mass number (or atomic weight)

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88
Q

The number of protons inside the nucleus equals the number of ________ outside the nucleus.

A

Electrons

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89
Q

What does the number of protons and neutrons determine?

A

The atomic number

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90
Q

Is the nucleus affected by x-rays?

A

No, only the orbiting electrons

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91
Q

What charge do electrons hold?

A

Negative charge

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92
Q

How do electrons travel around the nucleus?

A

in well defined paths known as orbits or shells

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93
Q

Does the shell closest to the nucleus have the highest or lowest energy level?

A

highest

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94
Q

What layer or orbit of electrons may be disturbed most during dental radiography?

A

The outer layer

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95
Q

How are electrons maintained in their orbits?

A

By electrostatic force between the attraction of the positive nucleus and negative electrons

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96
Q

What is the electrostatic forces attraction between the positive nucleus and negative electrons called?

A

Binding energy of an electrons

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97
Q

What is binding energy determined by?

A

The distance between the nucleus and the orbiting electron

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98
Q

Where is the strongest binding energy located?

A

Closest to the nucleus in the K shell

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99
Q

What is the relationship between the location of the shells and the amount of binding energy?

A

The shells closest to the nucleus have the strongest binding energy, the farther away from the nucleolus the weaker the binding energy

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100
Q

What are the binding energies of orbital electrons measured in?

A

electron volts ( eV) or kilo electrons volts (keV)

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101
Q

What must the energy required to remove an electron from its orbital shell exceed?

A

The binding energy: Therefore removing electrons closest to the nucleus is much more difficult

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102
Q

What occurs when atoms combine with one another

A

it forms a molceule

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103
Q

What is a molecule?

A

two or more atoms joined by chemical bonds

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104
Q

What two ways are molecules formed?

A
  1. the transfer of electrons
  2. the sharing of electrons between the outermost shell of atoms
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105
Q

An atom with an incomplete filled outer shell will attempt to do what?

A

capture an electron from an adjacent atom

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106
Q

if the atom gains an electron while doing this what will its charge be?

A

negative

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107
Q

if the atom loses an electron while doing this what will its charge be?

A

positive

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108
Q

What is an ion?

A

an atom that gains or loses an electron and becomes electrically unbalanced.

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109
Q

What is ionization?

A

the production of ions or the process of the converting an atom into ions

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110
Q

What occurs when an electron is removed from an atom in the ionization process?

A

an ion pair results

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111
Q

What does the atom become when an electron is removed?

A

a positive ion

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112
Q

what does the ejected electron become?

A

a negative ion

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113
Q

Why is even the smallest change at a molecular level important?

A

may lead to big changes at the cellular level

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114
Q

What other factors affect the damage that may occur?

A

amount of ionization over an amount of time

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115
Q

What is radiation?

A

radiation is the emission and propagation of energy through space or a substance in the form of waves or particles

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116
Q

What is 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

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117
Q

Which is used in dentistry radiation or radioactivity?

A

radiation

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118
Q

what is propagation?

A

transmit or to be transmitted in a particular direction or through a medium

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119
Q

What is ionizing radiation?

A

radiation capable of producing ions by removing or adding electrons into an atom

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120
Q

What are the two classifications of ionizing radiation?

A
  1. particulate radiation
  2. electromagnetic radiation
121
Q

What is particulate radiation?

A

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

122
Q

What are the 4 types of particulate radiation?

A
  1. electrons
  2. alpha particles
  3. protons
  4. neutrons
123
Q

Particulate Radiation: (1) Electrons: What are beta particles?

A

fast moving electrons emitted from nucleus of radioactive atoms

124
Q

Particulate radiation: (1) Electrons: What are cathode rays?

A

streams of high speed electrons that originate in an x-ray tube. Electrons emitted by a manufactured device

125
Q

Particulate Radiation: What are (2) alpha particles?

A

emitted from the nuclei of heavy metals, they exist as two protons and neutrons with out electrons

126
Q

Particulate Radiation: (3) What is protons?

A

accelerated particles, specifically hydrogen nuclei, with a mass of 1 and a charge of +1

127
Q

Particulate Radiation: (4) What is neutrons?

A

Accelerated particles, with a mass of 1 and no electrical charge

128
Q

What is electromagnetic radiation?

A

propagation of wavelike energy (with out mass) through space or matter

129
Q

how are electromagnetic wave arranged?

A

in the electromagnetic spectrum according to their energies

130
Q

how is electromagnetic radiation made?

A

artificial or occur naturally

131
Q

What are two classifications of electromagnetic radiation?

A

ionizing or non ionizing

132
Q

In electromagnetic radiation only ______ are capable of ionization

A

high-energy radiations

133
Q

what are electromagnetic radiations believed to move through space as?

A

both a particle and a wave both concepts must be considered

134
Q

What is the particle concept?

A

charcterizes electromagnetic radiation in term of discrete bundles of energy called photons or quanta

135
Q

what are photons?

A

bundles of energy with no mass or weight

136
Q

How do photons travel?

A

as waves at the speed of light and move through space in a straight line

137
Q

What is the wave concept?

A

characterizes electromagnetic radiations as waves, with velocity, wave-length and frequency being considered

138
Q

what is velocity?

A

the speed of the wave

139
Q

what is wavelength

A

the distance between the crest of one wave and crest of the next

140
Q

what is frequency

A

the number of wavelengths that pass a certain point in a given time

141
Q

low wavelengths have low or high frequency?

A

low frequency

142
Q

short wavelengths have low or high frequency

A

high frequency

143
Q

What is x-radiation in terms of energy and type of radiation?

A

x-radiation is high-energy, ionizing electromagnetic radiation

144
Q

what are x-ray ?

A

weightless bundles of energy with no electrical charge that travels in waves with a specific frequency at the speed of light

145
Q

x-ray photons interact with the materials they penetrate and cause __________

A

ionization

146
Q

What part of the x-ray machine contains the x-ray tube that produces dental x-rays?

A

the tubehead

147
Q

What is the function of the metal housing in the tubehead

A

surrounds the tube and transformers, protects tube and grounds high voltage components

148
Q

what is the function of the insulating oil in the tubehead?

A

surround x-ray tube and transformers prevents over heating

149
Q

What is the function of the tube head seal in the tubehead?

A

permits exit of x-rays from tube head, seals the oil, filters x-ray beam

150
Q

What is the function of the x-ray tube in the tube head

A

heart of the generating system

151
Q

what is the function of the transformer in the tubehead?

A

alters voltage of incoming electricity

152
Q

What is the function of the aluminum disks in the tube head?

A

filter out non penetrating, longer wavelength x-rays in the tubehead

153
Q

What are the 3 components of the glass vaccuum tube?

A
  1. lead glass housing
  2. cathode
  3. anode
154
Q

What does the leaded glass vaccuum tube prevent/

A

x-rays from escaping in all directions

155
Q

What purpose does the “window” on the leaded glass vacuum tube permit?

A

the x-rays beam to exit the tube and directs the beam toward the aluminum disks, lead collimator and PID

156
Q

Is cathode negative or positive?

A

negative

157
Q

What does the negative cathode electrode supply?

A

the electrons necessary to generate x-rays

158
Q

What does the tungsten wire filament found in the cathode produce? how does heat affect this?

A

electrons when heated, the hotter the filament the more electrons are produced

159
Q

Cathode: what does the molybdenum cup focus, what is it purpose?

A

focuses electrons into a narrow beam and directs the beams toward the tungsten target

160
Q

Cathode: Where does the molybdenum cup keep the electrons? why?

A

near the cathode so that the instant the exposure button is pressed the circuit becomes complete and the electrons travel across the x-ray tube to the anode

161
Q

are anodes positive or negative?

A

positive

162
Q

How do electrons move? cathode to anode or anode to cathode?

A

cathode to anode

163
Q

What does the positive electrodes in the anode do to electrons?

A

concerts electrons into x-ray photons

164
Q

Most of x-rays (99%) are?

A

absorbed and given off as heat

165
Q

the remaining 1% of x-rays?

A

leaves and is directed towards the patient

166
Q

Anode: Consists of a tungsten plate embedded in a solid copper rod, What purpose does the tungsten target serve?

A

focal spot and converts electrons into photons

167
Q

Anode: What purpose does the copper stem serve?

A

dissipates heat away from the tungsten target

168
Q

In summary what is the purpose of the cathode?

A

filament is heated and emits electrons by thermionic emission

169
Q

In summary what is the purpose of the anode?

A

angled to deflect the beam towards the filtered or collimated opening

170
Q

What is the 3 simple steps of x-ray production?

A

A. when the filament circuit is activated the filament heats up, and thermionic emission occurs
B. When the exposure button is activated the electrons are accelerated from the cathode to the anode
C. the electrons strike the tungsten target and their kinetic energy is converted to x-rays and heat

171
Q

What is the energy used to make x-rays?

A

electricity

172
Q

what is electrical current?

A

a flow of electrons through a conductor

173
Q

What is (DC) Direct Current?

A

electrons flow in one direction through a conductor

174
Q

What is (AC) Alternating Current?

A

when electrons flow in two opposite directions

175
Q

What is rectification?

A

The conversion of AC to DC

176
Q

How does the x-ray tube head act as a self rectifier? How does this affect cathodes and anodes?

A

changes AC to DC while producing x-rays. Ensures current flows from cathode to anode

177
Q

What is amperage?

A

measurement of the number of electrons moving through a conductor

178
Q

How is current measured?

A

in amperes (A) or milliamperes (mA)

179
Q

What is voltage?

A

measurement of electrical force that causes electrons to move from a negative pole to a positive one

180
Q

What is voltage measured in?

A

Volts (V) or Kilovolts (kV)

181
Q

What does adjusting the mA affect?

A

increases or decreases the number of electrons passing through the cathode filament

182
Q

Was does adjusting the kilo voltage peak (kVp) affect?

A

controls the current passing from the cathode to anode

183
Q

Can you manually change the mA and kVp?

A

most dental x-ray units operate at a fixed mA and kVp

184
Q

what is the most often adjusted element of the x-ray machine?

A

the exposure time

185
Q

What two electrical ciruits are used in production of x-rays

A
  1. low voltage or filament circuits
  2. high-voltage circuit
186
Q

What is the low voltage or filament circuit

A

3-5 volts
regulated the flow of electrical current to the filament

187
Q

How is low voltage/ filament circuit controlled

A

Controlled by milliamperage (mA)

188
Q

What is high-voltage circuit?

A
  • 65,000 to 100,000 volts
    provides high voltage required to accelerate electrons and to generate heat
189
Q

How is high voltage circuit controlled?

A

controlled by kV

190
Q

What is the use of a transformer?

A

used to ethier increase or decrease the voltage in an electircal circuit

191
Q

What 3 transformers are used to adjust the electrical circuits

A
  1. step-down transformer
  2. step up transformer
  3. autotransformer
192
Q

What is the step down transformer?

A

used to decrease voltage from the incoming 110-220 line voltage to the 3 to 5 volts used by the filament (low voltage) circuit

193
Q

How does the current travel with step down transformer

A

current travels through the step down transformer to the filament of the cathode

194
Q

What is the step up transformer?

A

used to increase incoming voltage to 65,000 to 100,000 volts used by the high voltage circuit.

195
Q

What is the autotransformer

A

serves as a voltage compensator that corrects for minor fluctuation in current

196
Q
  1. Higher mA increasing filament temperature how does this effects the electrons electrons in the cathode?
A

more electrons are produced

197
Q
  1. More electrons hitting the anode mean _____ x-rays leaving tube. and with ______ forcer and energy
A

more, greater

198
Q

This produces ______ wavelengths and therefore a ______ penetrating beam

A

shorter, more

199
Q

Why are longer wavelengths removed?

A

they are less penetrating and thus not useful for dental radiogrpahy

200
Q

Two mechanisms of radiation ( depending on tungsten target)

A
  1. general (braking) radiation
  2. Characteristic radiation
201
Q

What is general (braking) radiation?

A

makes up 85%
the term breaking refers to the sudden stopping of high speed electrons when they hit the tungsten target in the anode

202
Q

What is characterstic radiation?

A

makes up 15%
accounts for a very small part of x-rays produced in the dental x-ray machine
this is where kinetic energy of the electrons is converted into x-rays

203
Q

When an electron that passes close or hits the nucleus of a tungsten atom is slowed down, an x-ray photon of lower energy known as ________________ results

A

general braking radiation

204
Q

When is characteristic radiation produced?

A

when high speed incoming electron dislodges an inner-shell electrons from a tungsten atom and causes ionization of that atom

205
Q

What occurs with the remaining orbiting electrons?

A

they are rearranged to fill the vacancy

206
Q

what does the rearrangement produce?

A

a loss of energy that results in the production of an x-ray photon

207
Q

What is primary radiation?

A

the penetrating x-ray beam that is produced at the target of the anode (primary beam)

208
Q

What is secondary radiation?

A

x-radiation created when the primary beam interacts with matter ( soft tissues of head, bones of skill and teeth)
- less penetrating than primary

209
Q

What is scatter radiation?

A

a form of secondary radiation, the result of an x-ray that has been deflected from its path by an interaction with matter
- detremental to both patient and radiogrpaher

210
Q

What are the 4 possible interaction of x-radiation

A
  1. no interaction
  2. coherent scatter
  3. compton scatter
  4. absorption of energy and photelectric effect
211
Q

What is no interaction?

A

the x-ray photon passes through the atom unchanged and leaves the atom unchanged
- responsible for densities on film

212
Q

what is coherent scatter?

A

an x-ray photon that has its path altered by matter

213
Q

How does coherent scatter work?

A

a low energy xray photon interacts with an outer shell electron
no change in the atom occurs and a xray photon of scatter radiation is produced
the xray photon changes direction thus going unmodified

214
Q

What is comptom scatter

A

the xray photon is deflected from its path during its passage through matter
- IONIZATION takes place

215
Q

How does Compton scatter work?

A

an x ray photon collides with a loosley bound outer shell electron and give up part of its energy to eject and electron from its orbit
- the xray photon loses energy and continues in a different direction at a lower energy level

216
Q

what is the ejected electron termed in compton scatter

A

compton electron

217
Q

What is absorption of energy and photelectric effect?

A

the xray photon is completely absorbed within matter or the tissue of the patient

218
Q

true or false: photoelectric effect is responsible for most of the attenuation in medical and dental radiographic images

A

true

219
Q

what is absorption in the photoelectric effect?

A

the total transfer of energy from photon to the atoms of matter

220
Q

what is the photoelectric effect?

A

an xray photon collides with a tightly bound inner shell electron and gives up all its energy to eject the electron from its orbit

221
Q

when an x ray beam passes through matter it goes through a process called?

A

attenuation

222
Q

what is it called when photons go through with out interacting?

A

direct transmission
- reach the receptor and show up black

223
Q

which is it called when phtons are scattered by compton interaction but still go through

A

indirect transmission
- reach the receptor but degrade the image making it blurry and harder to see anatomy

224
Q

many photons will interact with atoms in the material and be ________ by photoelectric absorption

A

attenuated

225
Q

When attenuated do they reach the image receptor

A

no

226
Q

What do attenuated images do

A

create contrast and allow up to see different structures
- shows up as white or shades of white on the image

227
Q

What is radiation biology?

A

the study of the effects of ionizing radiation on living tissue

228
Q

Does all x ray beams reach the dental x ray film?

A

not all some re absorbed by the patients tissues

229
Q

What two mechanisms of radiation injury are possible?

A
  1. ionization
  2. free radical formation
230
Q

When does ionization result?

A

when x-rays strike patient tissue

231
Q

how is ionization produced? (2)

A

through photoelectric effect or Compton scatter

232
Q

what does ionization result in?

A

positive atom and dislodged negative electron

233
Q

How does the dislodged electron interact with other atoms

A

can cause chemical changes within the cell resulting in biologic damage

234
Q

cell damage occurs primarily through?

A

formation of free radicals

235
Q

how are free radicals formed?

A

when an x-ray photon ionizes water

236
Q

What is a free radical?

A

an uncharged atom or molecule that exists with a single, unpaired electron in its outermost shell
- highly reactive and unstable

237
Q

what can free radicals combine to form?

A

toxins such as hydrogen peroxide

238
Q

damage to living tissue caused by exposure to ionizing radiation may result from what two things

A
  1. a direct hit and absorption of an x-ray photon within a cell
  2. absorption of an x-ray photon by water within a cell accompanied by free radical formation
239
Q

What two therories describe how radiation damages biologic tissues

A
  1. direct theory
  2. indirect theory
240
Q

what is direct theory?

A

cell damage results when ionizing radiation directly hits critical areas within the cell
- occurs infrequently, most photons pass through the cell and cause little to no damage

241
Q

what is indirect theory?

A

when x-ray photons are absorbed by water within the cell a free radical is formed
- the free radicals combine to form toxins that damage cells

242
Q

what occurs more frequently indirect or direct theory?

A

indirect theroy

243
Q

is there a safe amount of radiation expsosure?

A

no

244
Q

does damage occur with every exposure?

A

yes

245
Q

what is curve used for?

A

to correlate the damage to tissue with the dose of radiation received

246
Q

what type of relationship is seen with the curve

A

a linear non thresh-hold

247
Q

what is a threshold curve?

A

indicates that below a certain level (threshold) no response is seen

248
Q

what is a non threshold curve?

A

indicates that the response of the tissues is directly proportional to the dose

249
Q

what are stochastic effects?

A

a direct function of the dose
no dose threshold effects do not depend on the magnitude of the absorbed dose
ex. cancer, tumours and genetic mutations

250
Q

what are non stochastic (deyerministic) effects

A

occur after a threshold of exposure has been exceeded larger doses needed
increase in severity with increased absorbed dose
ex. erythema, loss of hair decreased fertility

251
Q

What is the latent period?

A

the time that elapses between exposure to ionizing radiation and the appearance of observable clinic signs or symptoms

252
Q

what is the period of injury?

A

after the latent period, a variey of cellular injuries may result ( cell death, changes in cell function)

253
Q

what is the recovery period?

A

last event in the sequence of radiation injury
- depending on a number of factors cells can repair the damaged caused

254
Q

what are cumulative effects?

A

effects of radiation exposure are additive
- un repaired damage accumulates in tissues

255
Q

who is most susceptible for radiation injury?

A

children

256
Q

What is total dose?

A

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

  • more damage occurs when tissue absorbs large quantities of radiation
257
Q

What is the dose rate rate

A

rate at which exposure occurs and absorption takes place

258
Q

How do you calculate dose rate?

A

dose divided by time

259
Q

extensive radiation injury occurs when? what does it damage?

A

large areas of the body are exposed and it damages blood forming tissues

260
Q

what cells are more susceptible and sensitive to radiation

A

rapidly dividing cells and young cells

261
Q

What is short term effects?

A

Associated with large doses of radiation in a short amount of time

262
Q

What is Acute Radiation Syndrome (ARS)

A

includes nausea, vomiting, diarrhea, hair loss and hemorrhage

263
Q

When do you see short term affects?

A

minutes, days or weeeks

264
Q

are short term affects seen in dentistry?

A

no

265
Q

What is long term effects?

A

small doses absorbed repeatedly over a long period of time

266
Q

How long after do you see long term effects?

A

years, decades or generations as cancer, birth defects and genetic abnormalities

267
Q

What are somatic cells?

A

all cells in the body expect the reproductive cells

268
Q

What are genetic cells?

A

the reproductive cells

269
Q

What are somatic effects?

A

seen in a person who has been irradiated- poor health, cancer, leukemia
NOT transmitted to future generations

270
Q

What are genetic effects

A

not seen in the person irradiated but are passed on to future generations
- genetic mutations are not apparent unit the next generation

271
Q

What is a radiosensitive cell?

A

a cell that is sensitive to radiation

272
Q

what is a radio-resistant cell?

A

a cell that is resistant to radiation

273
Q

what 3 factors determine the response of the cell being radiosensitive or radioresistant?

A
  • mitotic activity
  • cell differentiation
  • cell metabolism
274
Q

What is mitotic activity?

A

a cell that divides more frequently is radio sensitive

275
Q

what is cell differentiation?

A

cells that are immature or are not highly specialized are more radio sensitive

276
Q

what is cell metabolism?

A

cells that have a higher metabolism are more radiosensitive

277
Q

what is the most radiosensitive cell in the body?

A

lymphocyte

278
Q

bone, muscles and nerves are _________ cells?

A

radio resistant

279
Q

what are some radiosensitive organs?

A
  • lymphoid tissue
  • bone marrow
  • testes and female eggs
  • intestines
280
Q

what are some radioresistant tissues?

A
  • salivary glands
    -kidney
    -liver
  • muscles
    nerves
281
Q

what is a critical organ?

A

an organ that, if damaged dimishes the quality of life
ex. heart, liver and lungs

282
Q

what are critical organs in dental radiography?

A
  • skin
    -thyroid gland
    -lens of eye
  • bone marrow
283
Q

What is the traditional unit of radiation measurement?

A

Roentgen (R)

284
Q

What is the newer unit of radiaiton measurement?

A

SI

285
Q

What does Roetgen (R) measure?

A

the amount of ionization that occurs in air

286
Q

What is the dose measurement?

A

the amount of energy absorbed by tissue

287
Q

What is the traditional unit and what does it stand for

A

Rad- radiation, absorbed, dose

288
Q

What is the SI equivalent

A

Gray
1 Gy= 100 rad

289
Q

what is dose equivalent measurements used to compre?

A

biologic effects of different radiation

290
Q

the gray and sievert are ____________ measurments

A

equal

291
Q

the roentgen, rad and gem are considered approx ________

A

equal

292
Q

in the US the average dose of background radiation received per year of around?

A

150-300 mrad per year

293
Q

What is the definition of a risk?

A

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

294
Q

what is the risk of fatal cancer in dental radiography i?

A

3 in 1 million

295
Q

is dental radiography risky?

A

death is more likely from common acitivies than dental images

296
Q

what 4 things determine the amount of exposure a patient receives

A
  1. receptor choice- film speed, digital vs film
  2. collimation- rectangular collimator can reduce dose by 60-70%
  3. technique- increase the target receptor distance
  4. exposure factors
297
Q

true or false 4 bite wing images is less than 1 day of backround exposure?

A

true, its equi alent to a short 1-2 hour flight

298
Q

What is alara

A

as low as reasonably achievable
- all radiaiton must be kept to a minimum to protect both operator and client

299
Q

why and how should dental images be prescribed?

A

only when the befit of disease detection outweighs the risk of biological damage. benefits far outweigh the risk

1102 Rad (4 decks)

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