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Oral Radiology > Radiation Biology- The basics (Exam II) > Flashcards

Radiation Biology- The basics (Exam II) Flashcards

1
Q

T/F: Ionizing radiation is NOT safe and there is always a biologic risk

A

true

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2
Q

Why do we have to learn ionizing radiation biology?

A
  1. education of the public
  2. protection of the public
  3. dental boards
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3
Q

What are the four different ways to measure radiation?

A
  1. exposure dose
  2. absorbed dose
  3. equivalent dose
  4. effective dose
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4
Q

What comes out of the tube head; ionize air:

A

exposure dose

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5
Q

Energy absorbed by tissue:

A

absorbed dose

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6
Q

Modified by radiation weighting factor; a way to put different types of radiation on an equal playing field; (absorbed dose multiplied by quality factor)

A

equivalent dose

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7
Q

How do you calculate the equivalent dose of radiation?

A

absorbed dose multiple by quality factor

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8
Q

Modified by tissue weight factor; a calculated dose- allows us to look at certain amounts of radiation for certain parts of the body :

A

effective dose

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9
Q

Exposure dose:

Traditional unit?
SI unit?
Conversion?

A

traditional unit: R

SI unit: air kerma

1R= 2.58 x10^-4 Coulombs/kg

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10
Q

Absorbed dose:

Traditional unit?
SI unit?
Conversion?

A

traditional unit: rad

SI unit: Gray (Gy)

1 Gy= 100 rads

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11
Q

Equivalent dose:

Traditional unit?
SI unit?
Conversion?

A

traditional unit: rem

SI unit: Sievert (Sv)

1 Sv= 100 rems

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12
Q

Effective dose:

Traditional unit?
SI unit?
Conversion?

A

traditional unit: rem

SI unit: Sievert (Sv)

1 Sv= 100 rems

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13
Q

For x-radiation the ___ dose and the ____ dose are the same thing:

A

absorbed dose & equivalent dose

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14
Q

What is the quality factor for x-radiation?

A

1

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15
Q

What type of radiation does the following describe?

R vs. Coulombs/kg

A

exposure dose

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16
Q

What type of radiation does the following describe?

RAD vs. Gray (Gy)

A

absorbed dose

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17
Q

What type of radiation does the following describe?

REM vs. Sievert (Sv)

A

equivalent dose & effective dose

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18
Q

Of the following, which is the most important?

  1. exposure dose
  2. absorbed dose
  3. equivalent dose
  4. effective dose
A

effective dose

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19
Q

a measure of the capacity of radiation to ionize air:

A

exposure dose

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20
Q

Traditional unit of exposure dose:

A

Roentgen (R)

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21
Q

Tradition unit: ____ (_)= produce 2.08 x 10^9 ion pairs in 1.0 cc of air at standard temperature and pressure

A

Roentgen (R)

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22
Q

Metric equivalent unit (S.I): air kerma (___)= sum of the kinetic energy of all liberated charged particles/mass (Coulomb/kg)

A

kinetic energy released in matter

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23
Q

What does kerma stand for?

A

kinetic energy released in matter

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24
Q

1 R = ___ coulombs/ kg

1 coulomb/kg= ___R

A

2.58 x 10^-4

3.88 x10^3

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25
Q

Unit of radiation exposure that produces 2.08 x10^9 ion pairs in 1.0 cc of air at standard temp and pressure

A

Roentgen (R)

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26
Q

What is the acronym for absorbed dose:

A

RAD

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27
Q

What does RAD stand for?

A

Radiation Absorbed Dose

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28
Q

100 ergs or radiation energy in 1 gram of absorbed material

A

absorbed dose

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29
Q

1.0 Gy = ___ RAD

0.01 Gy= ___ RAD

A

100; 1

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30
Q

1 R= ___RAD

A

0.903 RAD

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31
Q

Used to compare the biological effects of different types of radiation:

A

Equivalent dose (I)

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32
Q

Represents radiation weighing factor:

A

W(R)

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33
Q

In what type of radiation does do we take into consideration the radiation weighing factor?

A

equivalent dose

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34
Q

The radiation weighing factor W(R) depends on:

A

the type and energy of the radiation involved

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35
Q

What is the equivalent dose for X-ray radiation (also quality factor?)?

A

1

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36
Q

For high energy radiation (NOT x-rays), the quality factor/equivalent dose is

A

greater than 1

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37
Q

The equivalent dose/quality factor for high energy protons is ____; and for alpha particles its ____

A

5; 20

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38
Q

Equation for equivalent dose:

A

H(T)= D(T) x W(R)

The parenthesis do not mean multiplication they mean subscript

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39
Q

In the equivalent dose equation

H(T)= D(T) x W(R)

What does each component represent?

A

H(T): equivalent dose
D(T): absorbed dose
W(R): radiation weighing factor

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40
Q

A measure of the biological effectiveness of radiation to ionize matter:

A

Quality factor (Q.F)

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41
Q

Quality factor (Q.F) is used for what type of radiation?

A

Equivalent dose

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42
Q

Acronym used with equivalent dose radiation:

A

REM

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43
Q

What does REM stand for?

A

Roentgen Equivalent in Man

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44
Q

____ is equivalent to RAD x QF

A

REM (equivalent dose)

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45
Q

Since the QF for x-radiation = 1; RAD units for x-radiation are equivalent to:

A

REM units

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46
Q

What is the SI unit for equivalent dose?

A

Sievert (Sv)

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47
Q

1 REM = ____ Sv
100 REM = ____ Sv

A

0.01 Sv; 1.0 Sv

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48
Q

Diagnostic x-radiation is measured in _____ or ____

A

millirems (mRem) or millSieverts (mSv)

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49
Q

Since 1R = 0.903 RAD = ____ REM

A

0.903

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50
Q

Since 1R = 0.903 RAD = 0.903 REM therefore 1mR= 1mRad= ____ mRem

A

1

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51
Q

What type of radiation does the following equation represent?

E= the sum of W(T) x H(T)

A

effective dose

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52
Q

This measure is used to specifically calculation risks of radiation to human tissues on a common scale:

A

effective dose

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53
Q

This calculation is a product of the sum of dose equivalence to the specific tissues or organs exposed and the biological tissue weighting factor:

A

effective dose

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54
Q

The effective dose is a product of the sum of ___ to the specific tissues or organs exposed and the ____

A

dose equivalence; biological tissue weighting factor

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55
Q

Use of the effective dose allows for comparisons of:

A

different imaging techniques to be made on a common scale

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56
Q

This value is an estimated measure of all somatic and genetic radiation-induced risk even if the entire body is not uniformly exposed:

A

effective dose

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57
Q

The effective dose value is an estimated measure of all ______ and ____ even if the entire body is not uniformly exposed.

A

somatic and genetic radiation-induced risk

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58
Q

Used to assess the risk of non-uniform radiation to a localized part of the body and degree to which this would increase a person’s “whole body” risk of cancer or genetic mutations:

A

effective dose

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59
Q

Effective dose is used to assess the risk of non-uniform radiation to a localized part of the body and degree to which this would increase a person’s “whole body” risk of: (2)

A
  1. cancer induction
  2. induction of genetic mutations
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60
Q

cancer induction and or induction of genetic mutations re considered:

A

stochastic effects

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61
Q

Gonads: 0.20
Hematopoietic tissues: 0.12
Esophagus: 0.05
Thyroid: 0.05
Skin: 0.01
Cortical bone: 0.01

These are all examples of:

A

weighting factors of different tissues

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62
Q

The area exposed by radiation is related to the:

A

maximum size of the beam

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63
Q

What type of collimator allows for a more direct radiation exposure?

A

rectangular collimator

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64
Q

Used specifically to calculate risks of radiation to human tissues on a common scale. The calculation is a product of the sum of dose equivalence to the specific tissue exposed and the biological tissue weight factor/tissue sensitivity factor

A

effective dose

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65
Q

When comparing the equivalent dose to the absorbed dose, for radiation higher than QF =1 , the ____ dose will be higher than the ___ dose

A

equivalent will be higher than the absorbed dose

66
Q

What type interaction of x-radiation with matter is shown?

A

Compton scattering (incoherent)

67
Q

What type interaction of x-radiation with matter is shown?

A

photoelectric effect

68
Q

Both the Compton scatter and photoelectric effect produce:

A

secondary electrons (ionization)

69
Q

What are the deterministic effects of ionization?

A
  1. lethal DNA damage
  2. Cell death
  3. Decreased tissue and organ function
70
Q
  • xerostomia
  • osteoradionecrosis
  • cataracts
  • decreased fetal development

These are all examples that can occur with:

A

deterministic effects

71
Q

What are the three outcomes of biochemical lesions caused by ionization? (3)

A
  1. deterministic effects
  2. stochastic effects
  3. enzymatic repair
72
Q

What are stochastic effects of ionization (3)?

A
  1. sub-lethal DNA damage
  2. gene mutation
  3. replication of mutated cells
73
Q
  • leukemia
  • thyroid cancer
  • salivary gland tumors
  • heritable disorders

These are all all examples that can occur with:

A

stochastic effects

74
Q

Ionization from exposure sets a multitude of direct and indirect molecular reactions in:

A

less than 1 second

75
Q

Enzymatic repair of further deleterious molecular changes occur in:

A

minutes to hours

76
Q

Deterministic and stochastic effects take place over time from:

A

months, to decades to generations

77
Q

Of the interactions of x-radiation with matter, which are non-ionizing (2)?

A
  1. No interaction (9%)
  2. Coherent (Thomson) scatter (7%)
78
Q

x-ray photon enters object (patient or tissues) and exits with no change in its energy:

A

no interaction

79
Q

x-ray photon collides with an orbital electron and loses its energy AND the ejected photoelectron does its energy resulting in an atom with an altered electric state (i.e. + charge)

A

photoelectric interaction

80
Q

Similar orbital electron reaction to characteristic radiation production but no x-radiation is produced:

A

photoelectric interaction

81
Q

In the photoelectric interaction, the ionized matter is unstable and seeks:

A

a more stable configuration

82
Q

If the degree of the photoelectric effect is significant, this may affect:

A

biologic structure, function, or both

83
Q

The effects of photoelectric interaction are often:

A

deleterious biologic changes (examples = altered metabolic function, malignancy, etc.)

84
Q

x-ray photon collides with an outer orbital electron losing some energy, the x-ray photon continues in different direct with less energy creating more scatter until all the energy is lost:

A

compton interaction/scatter

85
Q

Compton interaction/scatter results in an:

A

atom with an altered electric state (i.e., + charge)

86
Q

In the Compton interaction/scatter, the ionized matter is unstable and seeks:

A

a more stable configuration

87
Q

In Compton interaction/scatter, if the degree of the photoelectric effect is significant:

A

this may affect biologic structure, function, or both

88
Q

With compton interaction/scatter, the effects are often:

A

deleterious biological changes (examples- altered metabolic function, malignancy, etc.)

89
Q

x-ray photon of low energy interacts with an outer orbital electron and CHANGES DIRECTION; no photoelectron is produced and therefore no ionization occurs:

A

coherent (Thomson) scatter (7%)

90
Q

When an x-ray photon is scattered and no loss of energy occurs, the scatter is termed:

A

coherent

91
Q

Mechanisms of injury from x-ray interaction with matter may be:

A

direct or indirect

92
Q

For direct and indirect mechanisms of radiation injury from x-ray interaction with matter:

  1. Both effects occur:
  2. Both effects take:
  3. Both effects are a result of:
A
  1. quickly
  2. hours or days to become evident
  3. ionization
93
Q

Describe the direct effect of biologic injury and its prevalence:

A
  1. directly ionizes biologic macromolecules
  2. accounts for 1/3 of biologic effects
94
Q

Describe the indirect effect of biologic injury and its prevalence:

A
  1. x-ray photons are absorbed by H2O resulting in free radicals which then lead to biologic damage
  2. accounts for 2/3 of biologic effects
95
Q

With indirect effects of biologic injury, what is the middle man actually causing damage?

A

Free radicals (H and OH) from H2O

96
Q

What are the 3 outcomes of radiation causing direct DNA damage (DNA DSB):

A
  1. repair leading to cell survival
  2. misrepair leading to carcinogenesis
  3. unprepared leading to cell death
97
Q

List the outcomes of direct effect of UV light on skin DNA: (3)

A
  1. Repair (healed)
  2. Inaccurate repair (mutation)
  3. No repair (death)
98
Q

Primary method of cell damage from radiolysis of water caused by x-radiation:

A

indirect effect

99
Q

The indirect effect causes ____ of water

A

radiolysis (producing free radicals)

100
Q

a free atom or molecule carrying an unpaired orbital electron in the outer shell:

A

free radical

101
Q

What does this equation represent?

Photon + H2O –> H2O* –> OH* + H*

A

indirect effect

102
Q

Free radicals are highly reactive and unstable with a lifetime of:

A

10^-10 seconds

103
Q

Free radicals seek a more stable configuration which results in formation of:

A

toxic substances

104
Q

amount of radiation is correlated with the response or damage:

A

dose

105
Q

T/F: Dose (amount) of radiation is correlated with the response or damage

A

true

106
Q

Curves are ____ for diagnostic x-radiation

A

theoretical

107
Q

In a threshold non-linear curve, small exposures to a substance:

A

do NOT produce measurable changes

108
Q

In a threshold non-linear curve, a ____ must be reached before changes are observed

A

theshold

109
Q

In general, most biologic effects are:

A

non-linear

110
Q

In a ____ curve, the dose is proportional to the response

A

linear non-threshold curve

111
Q

DOSE IS PROPORTIONAL TO THE RESPONSE:

A

Linear non-threshold curve

112
Q

A CERTAIN VALUE MUST BE REACHED BEFORE CHANGES ARE OBSERVED:

A

threshold non-linear curve

113
Q

In this type of curve, no matter how small the dose, there is some damage or risk

A

linear non-threshold curve

114
Q

Curve in which there is NO threshold and minimal damage at first with increased rate of damage with increased dose:

A

Non-linear non-threshold curve

115
Q

Does deterministic risk/effect have a threshold?

A

yes

116
Q

Describe the severity of the effect seen with deterministic risk/ effect

A

severity is proportional to dose

117
Q

List some examples of deterministic risk/effect: (7)

A
  1. erythema
  2. xerostomia
  3. cataract
  4. osteoradionecrosis
  5. fertility
  6. fetal development
  7. alopecia
118
Q

What is the fetal dose of OMR imaging?

A

0.01 mGy

119
Q

side effect of head and neck cancer treatment:

A

radiation erythema (large red area on neck)

120
Q

Do stochastic effects have a dose threshold?

A

no

121
Q

In ____ effects, the probability of occurrence is proportional to the dose

A

stochastic

122
Q

In ____ effects the severity of effects does NOT depend on the dose:

A

stochastic

123
Q

Deterministic effects:
- Have a threshold
- Severity is proportional to the dose

Stochastic effects:
- Have no dose threshold
- Probability of occurrence is proportional to the dose
- Severity of effects does NOT depend on dose

A
124
Q
  • no affect on parent
  • affects future generation
A

genetic injury

125
Q
  • affects parent
  • no affect on future generation
A

somatic injury

126
Q

effects/mutations are seen in the period irradiated:

A

somatic

127
Q

List the sequence of radiation injury:

A
  1. latent period
  2. period of injury
  3. recovery period
128
Q

Time that elapses between exposure and appearance of clinical signs:

A

latent period

129
Q

The latent period may be long or short depending on:

A
  1. total dose
  2. dose rate
130
Q

What may result in a shorter latent period?

A
  • increased amount of radiation
  • faster dose rate
131
Q

Describe the latent period with genetic effects:

A

may be generations before clinical effects are seen

132
Q

Describe what may occur in the period of injury: (6)

A
  1. cell death
  2. changes in cell function
  3. breaking or clumping of chromosomes
  4. giant cell formation
  5. cessation of mitotic activity
  6. abnormal mitotic activity
133
Q

Factors modifying effects of x-radiation include: (6)

A
  1. total dose
  2. dose rate
  3. oxygen
  4. area exposed
  5. cell type and function
  6. age
134
Q

Describe the relationship of total dose and damage:

A

as total dose increases; damage increases

135
Q

Describes the frequency of dose delivery:

A

dose rate

136
Q

Describe the relationship of dose rate, cellular repairs, and damages:

A

as dose rate increases; cellular repairs decrease; damages increase

137
Q

A high dose rate kills more cells because:

A

less time exists for repair of sublethal damage

138
Q

Describe the relationship of oxygen content, radio sensitivity, and tissue damage:

A

Increased oxygen content; increased radiosensitivity; increased tissue damage

139
Q

The presence of oxygen ____ the cells sensitive to radiation

A

increases

140
Q

Cell type vs. radio sensitivity is known as ____ classification

A

casarett classification

141
Q

radiosensitivity of young, immature, rapidly growing and dividing, least specialized:

A

radiosensitive

142
Q

radiosensitivity of mature, specialized cells:

A

radioresistant

143
Q

Describe species radiosensitivity:

A

mammals are more sensitive than reptiles, insects, and bacteria

144
Q

Describe how mitotic activity affects radiosensitivity: (2)

A
  1. increase in frequency of cell division results in increased sensitivity
  2. immature cells/not highly specialized have an increased sensitivity
145
Q

Describe how cell metabolism effects radiosensitivity:

A

increased metabolism causes and increase in sensitivity

146
Q

Describe the relative sensitivity of the following tissues/organs:

  • blood cells
  • small lymphocytes
  • bone marrow
  • reproductive cells
  • intestinal mucosa
  • mucous membrane
A

high sensitivity to radiation (LEAST RADIORESISTANT)

147
Q

What is the MOST sensitive type of cell to radiation? (LEAST radioresistant)

A

small lymphocytes

148
Q

Describe the relative sensitivity of the following tissues/organs:

  • connective tissue
  • breast (women)
  • small blood vessels
  • growing bone and cartilage
  • salivary gland
A

intermediate sensitivity to radiation

149
Q

Describe the relative sensitivity of the following tissues/organs:

  • thyroid gland
  • skin
A

fairly low sensitivity to radiation

150
Q

Describe the relative sensitivity of the following tissues/organs:

  • muscle
  • nerve
  • mature bone
A

low sensitivity to radiation (MOST radio resistant)

151
Q

Why are pediatric patients more at risk of cellular damage caused by radiation? (2)

A
  1. rate of cellular and organ growth puts tissues at greatest level of radiosensitivity
  2. Greater life expectancy puts children at 2-10x greater risk of being afflicted with a radiation induced cancer
152
Q

Females less than 10 years old are ___x more likely to develop fatal cancer than a 50 year old

A

~5-6x

153
Q

Males less than 10 years old are ___x more likely to develop fatal cancer than a 50 year old

A

~4-5x

154
Q

20 year old females are ___x more likely to develop fatal cancer than 50 year olds

A

~3.5x

155
Q

30 year old females are ___x more likely to develop fatal cancer than 50 year olds

A

~3x

156
Q

4-26-1986 - the meltdown and explosion that tripled the world’s background radiation level:

A

Chernobyl

157
Q

3-11-2011- an 8.9 magnitude earthquake and subsequent tsunami that overwhelmed the cooling systems of an aging reactor along Japans northeast coastline. This accident triggered explosions at several reactors at the complex, forcing a widespread evacuation in the area around the plant:

A

Fukushima Diachi

158
Q

A collection of signs and symptoms following acute whole-body radiation exposure:

A

acute radiation syndrome

159
Q

Where do we derive our information in regards to acute radiation syndrome? (3)

A
  1. animal experiments
  2. patient therapeutic radiation exposures
  3. atomic bombings & radiation accidents
160
Q

Acute radiation syndrome:

Sub-lethal exposure:

Lethal exposure

Supralethal exposure:

A

sub-lethal: less than 2Gy (200 rads)

lethal: ~2-8 Gy (~200-800 rads)

supra lethal: greater than 8 Gy (800 rads)

161
Q

With acute radiation syndrome, higher dose, shorter latent period and:

A

rapid onset of severe symptoms

162
Q
A

Oral Radiology (21 decks)

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