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Oral Radiology > Radiation Biology- The basics (Exam 2) > Flashcards

Radiation Biology- The basics (Exam 2) 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. equalvalent 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 X 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 different parts of the body:

A

Effective dose

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9
Q

Exposure dose:

Traditional unit?
SI unit?
Conversion?

A

Tradition unit: R
SI unit: air kerma
Conversion: 1R = 2.58x10^-4 Coulombs/Kg

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10
Q

Absorbed dose:

Traditional unit?
SI unit?
Conversion?

A

Traditional unit: rad
SI unit: Gray (Gy)
Conversion: 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)
Conversion: 1 Sv = 100 rem

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12
Q

Effective dose:

Traditional unit?
SI unit?
Conversion?

A

Traditional unit: rem
SI: Sievert (Sv)
Conversion: 1 Sv = 100 rem

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13
Q

For X-radiation, the ____ dose and ____ dose are the same

A

Absorbed doe & 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

Both equivalent and effective dose

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18
Q

Of the following which is 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 (___) = the 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 x 10^3

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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 temperature 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

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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 dose 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 of 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 is ____

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 jus 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 Q.F

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 S.I. 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 millisieverts (mSv)

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49
Q

1R = 0.903 RAD = ____ REM

A

0.903

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50
Q

Since 1R = 0.903 RAD = 0.903 REM
therefore 1 mR = 1 mRAD= _____ 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 calculate 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

Effective dose is the 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 are 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 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 to absorbed dose, for radiation higher than QF of 1, the ____ dose will be higher than the ____ dose

A

Equivalent will be higher than the absorbed

66
Q

What type of interaction of X-radiation is shown:

A

Compton (Incoherent) scattering

67
Q

What type of interaction of X-radiation is shown:

A

Photoelectric effect

68
Q

Both the Compton scatter & 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 & 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?

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

What are stochastic effects of ionization?

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 examples that can occur with:

A

Stochastic effects

74
Q

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

A

Less than 1 second

75
Q

Enzymatic repair or 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-ray radiation with matter, which are non-ionizing? (2)

A
  1. no interactions (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 loses 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 biological changes (examples = altered metabolic functions, malignancy, etc.)

84
Q

X-ray photon collides with an outer orbital electron losing some energy, the X-ray photon continues in different direction 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 radiation injury from X-ray interaction with matter may be:

A

direct or indirect

92
Q

For direct & indirect mechanism 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 to decades to become evident
  3. ionization
93
Q

Describe direct effect of biologic injury & 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 & 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 three 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 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

The amount of radiation is correlated with 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

threshold

109
Q

In general, most biologic effects are:

A

non-linear

110
Q

In a _____ curve the dose is proportional to response

A

linear non-threshold

111
Q

DOES IS PROPORTIONAL TO RESPONSE:

A

linear non-threshold curve

112
Q

A CERTAIN VALUE MUST BE REACHED BEFORE CHANGES OCCUR:

A

threshold non-linear curve

113
Q

In this type of curve, no matter how 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

Nonlinear 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 the 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 effect:
-Have a threshold
-the severity is proportional to the dose

Stochastic effect:
-No dose threshold
-probability of occurrence is proportional to dose
-severity of effects does not depend on dose

A
124
Q

-no affect on parent
-affects future generations

A

Genetic injury

125
Q

-affects parent
-no affect on future generation

A

Somatic injury

126
Q

Effects/mutations are seen in the person 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 relationship of total dose & 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, radiosensitivity & tissue damage:

A

Increased oxygen content: increased radiosensitivity: increased tissue damage

139
Q

The presence of oxygen ______ the cells sensitivity to radiation

A

increases

140
Q

Cell type vs. radiosensitivity 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 & bacteria

144
Q

Describe how mitotic activity effects radiosensitivity: (2)

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

Describe how cell metabolism effects radiosensitivity:

A

Increased metabolism causes an 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 radio resistant):

A

Small lymphocytes

148
Q

Describe the relative sensitivity of the following tissues/organs:

-connective tissue
-breast (women)
-small blood vessels
-growing bone & 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 radioresistant)

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 ____ times more likely to develop fatal cancer than a 50 year old

A

~5-6x

153
Q

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

A

~4-5x

154
Q

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

A

~3.5x

155
Q

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

A

~3x

156
Q

4/26/1986- The meltdown and explosion that tripled the worlds 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 Japan’s northeast coastline. This accident triggered explosions at several reactors at the complex, forcing a widespread evacuation in the area around the plant:

A

Fukushima Daichi

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?

A
  1. Animal experiments
  2. patient therapeutic radiation exposures
  3. atomic bombing & radiation accidents
160
Q

Acute radiation syndrome:

Sub-lethal exposure:

Letal exposure:

Supralethal exposure:

A

Sub-lethal: less than 2 Gy (200 Rads)

Lethal: around 2-8 Gy (~200-800 Rads)

Supralethal: 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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