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
2
Q
Why do we have to learn ionizing radiation biology?
A
- education of the public
- protection of the public
- dental boards
3
Q
What are the four different ways to measure radiation?
A
- exposure dose
- absorbed dose
- equivalent dose
- effective dose
4
Q
What comes out of the tube head; ionize air:
A
exposure dose
5
Q
Energy absorbed by tissue:
A
absorbed dose
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
7
Q
How do you calculate the equivalent dose of radiation?
A
absorbed dose multiple by quality factor
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
9
Q
Exposure dose:
Traditional unit?
SI unit?
Conversion?
A
traditional unit: R
SI unit: air kerma
1R= 2.58 x10^-4 Coulombs/kg
10
Q
Absorbed dose:
Traditional unit?
SI unit?
Conversion?
A
traditional unit: rad
SI unit: Gray (Gy)
1 Gy= 100 rads
11
Q
Equivalent dose:
Traditional unit?
SI unit?
Conversion?
A
traditional unit: rem
SI unit: Sievert (Sv)
1 Sv= 100 rems
12
Q
Effective dose:
Traditional unit?
SI unit?
Conversion?
A
traditional unit: rem
SI unit: Sievert (Sv)
1 Sv= 100 rems
13
Q
For x-radiation the ___ dose and the ____ dose are the same thing:
A
absorbed dose & equivalent dose
14
Q
What is the quality factor for x-radiation?
A
1
15
Q
What type of radiation does the following describe?
R vs. Coulombs/kg
A
exposure dose
16
Q
What type of radiation does the following describe?
RAD vs. Gray (Gy)
A
absorbed dose
17
Q
What type of radiation does the following describe?
REM vs. Sievert (Sv)
A
equivalent dose & effective dose
18
Q
Of the following, which is the most important?
- exposure dose
- absorbed dose
- equivalent dose
- effective dose
A
effective dose
19
Q
a measure of the capacity of radiation to ionize air:
A
exposure dose
20
Q
Traditional unit of exposure dose:
A
Roentgen (R)
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)
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
23
Q
What does kerma stand for?
A
kinetic energy released in matter
24
Q
1 R = ___ coulombs/ kg
1 coulomb/kg= ___R
A
2.58 x 10^-4
3.88 x10^3
25
Unit of radiation exposure that produces 2.08 x10^9 ion pairs in 1.0 cc of air at standard temp and pressure
Roentgen (R)
26
What is the acronym for absorbed dose:
RAD
27
What does RAD stand for?
Radiation Absorbed Dose
28
100 ergs or radiation energy in 1 gram of absorbed material
absorbed dose
29
1.0 Gy = ___ RAD
0.01 Gy= ___ RAD
100; 1
30
1 R= ___RAD
0.903 RAD
31
Used to compare the biological effects of different types of radiation:
Equivalent dose (I)
32
Represents radiation weighing factor:
W(R)
33
In what type of radiation does do we take into consideration the radiation weighing factor?
equivalent dose
34
The radiation weighing factor W(R) depends on:
the type and energy of the radiation involved
35
What is the equivalent dose for X-ray radiation (also quality factor?)?
1
36
For high energy radiation (NOT x-rays), the quality factor/equivalent dose is
greater than 1
37
The equivalent dose/quality factor for high energy protons is ____; and for alpha particles its ____
5; 20
38
Equation for equivalent dose:
H(T)= D(T) x W(R)
The parenthesis do not mean multiplication they mean subscript
39
In the equivalent dose equation
H(T)= D(T) x W(R)
What does each component represent?
H(T): equivalent dose
D(T): absorbed dose
W(R): radiation weighing factor
40
A measure of the biological effectiveness of radiation to ionize matter:
Quality factor (Q.F)
41
Quality factor (Q.F) is used for what type of radiation?
Equivalent dose
42
Acronym used with equivalent dose radiation:
REM
43
What does REM stand for?
Roentgen Equivalent in Man
44
____ is equivalent to RAD x QF
REM (equivalent dose)
45
Since the QF for x-radiation = 1; RAD units for x-radiation are equivalent to:
REM units
46
What is the SI unit for equivalent dose?
Sievert (Sv)
47
1 REM = ____ Sv
100 REM = ____ Sv
0.01 Sv; 1.0 Sv
48
Diagnostic x-radiation is measured in _____ or ____
millirems (mRem) or millSieverts (mSv)
49
Since 1R = 0.903 RAD = ____ REM
0.903
50
Since 1R = 0.903 RAD = 0.903 REM therefore 1mR= 1mRad= ____ mRem
1
51
What type of radiation does the following equation represent?
E= the sum of W(T) x H(T)
effective dose
52
This measure is used to specifically calculation risks of radiation to human tissues on a common scale:
effective dose
53
This calculation is a product of the sum of dose equivalence to the specific tissues or organs exposed and the biological tissue weighting factor:
effective dose
54
The effective dose is a product of the sum of ___ to the specific tissues or organs exposed and the ____
dose equivalence; biological tissue weighting factor
55
Use of the effective dose allows for comparisons of:
different imaging techniques to be made on a common scale
56
This value is an estimated measure of all somatic and genetic radiation-induced risk even if the entire body is not uniformly exposed:
effective dose
57
The effective dose value is an estimated measure of all ______ and ____ even if the entire body is not uniformly exposed.
somatic and genetic radiation-induced risk
58
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:
effective dose
59
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)
1. cancer induction
2. induction of genetic mutations
60
cancer induction and or induction of genetic mutations re considered:
stochastic effects
61
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:
weighting factors of different tissues
62
The area exposed by radiation is related to the:
maximum size of the beam
63
What type of collimator allows for a more direct radiation exposure?
rectangular collimator
64
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
effective dose
65
When comparing the equivalent dose to the absorbed dose, for radiation higher than QF =1 , the ____ dose will be higher than the ___ dose
equivalent will be higher than the absorbed dose
66
What type interaction of x-radiation with matter is shown?
Compton scattering (incoherent)
67
What type interaction of x-radiation with matter is shown?
photoelectric effect
68
Both the Compton scatter and photoelectric effect produce:
secondary electrons (ionization)
69
What are the deterministic effects of ionization?
1. lethal DNA damage
2. Cell death
3. Decreased tissue and organ function
70
- xerostomia
- osteoradionecrosis
- cataracts
- decreased fetal development
These are all examples that can occur with:
deterministic effects
71
What are the three outcomes of biochemical lesions caused by ionization? (3)
1. deterministic effects
2. stochastic effects
3. enzymatic repair
72
What are stochastic effects of ionization (3)?
1. sub-lethal DNA damage
2. gene mutation
3. replication of mutated cells
73
- leukemia
- thyroid cancer
- salivary gland tumors
- heritable disorders
These are all all examples that can occur with:
stochastic effects
74
Ionization from exposure sets a multitude of direct and indirect molecular reactions in:
less than 1 second
75
Enzymatic repair of further deleterious molecular changes occur in:
minutes to hours
76
Deterministic and stochastic effects take place over time from:
months, to decades to generations
77
Of the interactions of x-radiation with matter, which are non-ionizing (2)?
1. No interaction (9%)
2. Coherent (Thomson) scatter (7%)
78
x-ray photon enters object (patient or tissues) and exits with no change in its energy:
no interaction
79
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)
photoelectric interaction
80
Similar orbital electron reaction to characteristic radiation production but no x-radiation is produced:
photoelectric interaction
81
In the photoelectric interaction, the ionized matter is unstable and seeks:
a more stable configuration
82
If the degree of the photoelectric effect is significant, this may affect:
biologic structure, function, or both
83
The effects of photoelectric interaction are often:
deleterious biologic changes (examples = altered metabolic function, malignancy, etc.)
84
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:
compton interaction/scatter
85
Compton interaction/scatter results in an:
atom with an altered electric state (i.e., + charge)
86
In the Compton interaction/scatter, the ionized matter is unstable and seeks:
a more stable configuration
87
In Compton interaction/scatter, if the degree of the photoelectric effect is significant:
this may affect biologic structure, function, or both
88
With compton interaction/scatter, the effects are often:
deleterious biological changes (examples- altered metabolic function, malignancy, etc.)
89
x-ray photon of low energy interacts with an outer orbital electron and CHANGES DIRECTION; no photoelectron is produced and therefore no ionization occurs:
coherent (Thomson) scatter (7%)
90
When an x-ray photon is scattered and no loss of energy occurs, the scatter is termed:
coherent
91
Mechanisms of injury from x-ray interaction with matter may be:
direct or indirect
92
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:
1. quickly
2. hours or days to become evident
3. ionization
93
Describe the direct effect of biologic injury and its prevalence:
1. directly ionizes biologic macromolecules
2. accounts for 1/3 of biologic effects
94
Describe the indirect effect of biologic injury and its prevalence:
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
With indirect effects of biologic injury, what is the middle man actually causing damage?
Free radicals (H and OH) from H2O
96
What are the 3 outcomes of radiation causing direct DNA damage (DNA DSB):
1. repair leading to cell survival
2. misrepair leading to carcinogenesis
3. unprepared leading to cell death
97
List the outcomes of direct effect of UV light on skin DNA: (3)
1. Repair (healed)
2. Inaccurate repair (mutation)
3. No repair (death)
98
Primary method of cell damage from radiolysis of water caused by x-radiation:
indirect effect
99
The indirect effect causes ____ of water
radiolysis (producing free radicals)
100
a free atom or molecule carrying an unpaired orbital electron in the outer shell:
free radical
101
What does this equation represent?
Photon + H2O --> H2O* --> OH* + H*
indirect effect
102
Free radicals are highly reactive and unstable with a lifetime of:
10^-10 seconds
103
Free radicals seek a more stable configuration which results in formation of:
toxic substances
104
amount of radiation is correlated with the response or damage:
dose
105
T/F: Dose (amount) of radiation is correlated with the response or damage
true
106
Curves are ____ for diagnostic x-radiation
theoretical
107
In a threshold non-linear curve, small exposures to a substance:
do NOT produce measurable changes
108
In a threshold non-linear curve, a ____ must be reached before changes are observed
theshold
109
In general, most biologic effects are:
non-linear
110
In a ____ curve, the dose is proportional to the response
linear non-threshold curve
111
DOSE IS PROPORTIONAL TO THE RESPONSE:
Linear non-threshold curve
112
A CERTAIN VALUE MUST BE REACHED BEFORE CHANGES ARE OBSERVED:
threshold non-linear curve
113
In this type of curve, no matter how small the dose, there is some damage or risk
linear non-threshold curve
114
Curve in which there is NO threshold and minimal damage at first with increased rate of damage with increased dose:
Non-linear non-threshold curve
115
Does deterministic risk/effect have a threshold?
yes
116
Describe the severity of the effect seen with deterministic risk/ effect
severity is proportional to dose
117
List some examples of deterministic risk/effect: (7)
1. erythema
2. xerostomia
3. cataract
4. osteoradionecrosis
5. fertility
6. fetal development
7. alopecia
118
What is the fetal dose of OMR imaging?
0.01 mGy
119
side effect of head and neck cancer treatment:
radiation erythema (large red area on neck)
120
Do stochastic effects have a dose threshold?
no
121
In ____ effects, the probability of occurrence is proportional to the dose
stochastic
122
In ____ effects the severity of effects does NOT depend on the dose:
stochastic
123
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
124
- no affect on parent
- affects future generation
genetic injury
125
- affects parent
- no affect on future generation
somatic injury
126
effects/mutations are seen in the period irradiated:
somatic
127
List the sequence of radiation injury:
1. latent period
2. period of injury
3. recovery period
128
Time that elapses between exposure and appearance of clinical signs:
latent period
129
The latent period may be long or short depending on:
1. total dose
2. dose rate
130
What may result in a shorter latent period?
- increased amount of radiation
- faster dose rate
131
Describe the latent period with genetic effects:
may be generations before clinical effects are seen
132
Describe what may occur in the period of injury: (6)
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
Factors modifying effects of x-radiation include: (6)
1. total dose
2. dose rate
3. oxygen
4. area exposed
5. cell type and function
6. age
134
Describe the relationship of total dose and damage:
as total dose increases; damage increases
135
Describes the frequency of dose delivery:
dose rate
136
Describe the relationship of dose rate, cellular repairs, and damages:
as dose rate increases; cellular repairs decrease; damages increase
137
A high dose rate kills more cells because:
less time exists for repair of sublethal damage
138
Describe the relationship of oxygen content, radio sensitivity, and tissue damage:
Increased oxygen content; increased radiosensitivity; increased tissue damage
139
The presence of oxygen ____ the cells sensitive to radiation
increases
140
Cell type vs. radio sensitivity is known as ____ classification
casarett classification
141
radiosensitivity of young, immature, rapidly growing and dividing, least specialized:
radiosensitive
142
radiosensitivity of mature, specialized cells:
radioresistant
143
Describe species radiosensitivity:
mammals are more sensitive than reptiles, insects, and bacteria
144
Describe how mitotic activity affects radiosensitivity: (2)
1. increase in frequency of cell division results in increased sensitivity
2. immature cells/not highly specialized have an increased sensitivity
145
Describe how cell metabolism effects radiosensitivity:
increased metabolism causes and increase in sensitivity
146
Describe the relative sensitivity of the following tissues/organs:
- blood cells
- small lymphocytes
- bone marrow
- reproductive cells
- intestinal mucosa
- mucous membrane
high sensitivity to radiation (LEAST RADIORESISTANT)
147
What is the MOST sensitive type of cell to radiation? (LEAST radioresistant)
small lymphocytes
148
Describe the relative sensitivity of the following tissues/organs:
- connective tissue
- breast (women)
- small blood vessels
- growing bone and cartilage
- salivary gland
intermediate sensitivity to radiation
149
Describe the relative sensitivity of the following tissues/organs:
- thyroid gland
- skin
fairly low sensitivity to radiation
150
Describe the relative sensitivity of the following tissues/organs:
- muscle
- nerve
- mature bone
low sensitivity to radiation (MOST radio resistant)
151
Why are pediatric patients more at risk of cellular damage caused by radiation? (2)
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
Females less than 10 years old are ___x more likely to develop fatal cancer than a 50 year old
~5-6x
153
Males less than 10 years old are ___x more likely to develop fatal cancer than a 50 year old
~4-5x
154
20 year old females are ___x more likely to develop fatal cancer than 50 year olds
~3.5x
155
30 year old females are ___x more likely to develop fatal cancer than 50 year olds
~3x
156
4-26-1986 - the meltdown and explosion that tripled the world's background radiation level:
Chernobyl
157
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:
Fukushima Diachi
158
A collection of signs and symptoms following acute whole-body radiation exposure:
acute radiation syndrome
159
Where do we derive our information in regards to acute radiation syndrome? (3)
1. animal experiments
2. patient therapeutic radiation exposures
3. atomic bombings & radiation accidents
160
Acute radiation syndrome:
Sub-lethal exposure:
Lethal exposure
Supralethal exposure:
sub-lethal: less than 2Gy (200 rads)
lethal: ~2-8 Gy (~200-800 rads)
supra lethal: greater than 8 Gy (800 rads)
161
With acute radiation syndrome, higher dose, shorter latent period and:
rapid onset of severe symptoms
162
