1
Q
IT IS known beyond the WHAT that x-rays are harmful.
A
shadow of a doubt
2
Q
The effect of x-rays on humans is the result of interactions at the atomic level
A
HUMAN RADIATION RESPONSE
3
Q
This approach results in the greatest benefit with the lowest risk to patients and radiation
workers. This is the practice known as
A
ALARA—“as
low as reasonably achievable.”
3
Q
These atomic interac-
tions take the form of ionization or excitation of orbital electrons and result in the deposition of energy in tissue.
A
HUMAN RADIATION RESPONSE
4
Q
These atomic interac-
tions take the form of WHAT of orbital electrons and result in the deposition of energy in tissue.
A
ionization or excitation
4
Q
These atomic interac-
tions take the form of ionization or excitation of WHAT and result in the deposition of energy in tissue.
A
orbital electrons
5
Q
These atomic interac-
tions take the form of ionization or excitation of orbital electrons and result in the WHAT
A
deposition of energy in tissue.
5
Q
At what stage in the sequence, it is
possible to repair radiation damage and to
recover.
A
nearly every stage
5
Q
The abnormal molecule may in time function improperly or cease to function, which can result in serious of WHAT
A
in serious impairment or death of the cell.
5
Q
memorize this
A
DETERMINISTIC EFFECTS OF RADIATION ON
HUMANS
1. Acute radiation syndrome
a. Hematologic syndrome
b. Gastrointestinal syndrome
c. Central nervous system syndrome
2. Local tissue damage
a. Skin
b. Gonads
c. Extremities
3. Hematologic depression
4. Cytogenetic damage
STOCHASTIC EFFECTS OF RADIATION ON HUMANS
1. Leukemia
2. Other malignant disease
a. Bone cancer
b. Lung cancer
c. Thyroid cancer
d. Breast cancer
3. Local tissue damage
a. Skin
b. Gonads
c. Eyes
4. Shortening of life span
5. Genetic damage
a. Cytogenetic damage
b. Doubling dose
c. Genetically significant dose
EFFECTS OF FETAL IRRADIATION
1. Prenatal death
2. Neonatal death
3. Congenital malformation
4. Childhood malignancy
5. Diminished growth and development
6
Q
DETERMINISTIC EFFECTS OF RADIATION ON
HUMANS
A
- Acute radiation syndrome
a. Hematologic syndrome
b. Gastrointestinal syndrome
c. Central nervous system syndrome - Local tissue damage
a. Skin
b. Gonads
c. Extremities - Hematologic depression
- Cytogenetic damage
6
Q
STOCHASTIC EFFECTS OF RADIATION ON HUMANS
A
- Leukemia
- Other malignant disease
a. Bone cancer
b. Lung cancer
c. Thyroid cancer
d. Breast cancer - Local tissue damage
a. Skin
b. Gonads
c. Eyes - Shortening of life span
- Genetic damage
a. Cytogenetic damage
b. Doubling dose
c. Genetically significant dose
7
Q
EFFECTS OF FETAL IRRADIATION
A
- Prenatal death
- Neonatal death
- Congenital malformation
- Childhood malignancy
- Diminished growth and development
8
Q
This process is reversible. Ionized atoms can become
what by attracting a free electron.
A
neutral again
8
Q
This process is what. Ionized atoms can become
neutral again by attracting a free electron.
A
reversible
9
Q
This process is reversible. Ionized atoms can become
neutral again by what
A
attracting a free electron.
10
Q
Molecules
can be mended by repair what
A
enzymes.
11
Q
can be mended by repair enzymes.
A
Molecules
12
Q
can
regenerate and recover from radiation injury.
A
Cells and tissues
13
Q
If the radiation response increases in severity with
increasing radiation dose, and occurs within days after the radiation exposure.
A
deterministic effect
14
Q
if the incidence of the radiation response increases with increasing radiation dose and is not observed for months or years.
A
stochastic effect
15
Q
In addition, many other radiation responses
have been experimentally observed in what
A
animals
16
Q
is the study of the effects of
ionizing radiation on biologic tissue.
A
Radiobiology
17
Q
Most radiobiologic research seeks to develop WHAT so the effects of planned radiation doses can be predicted and the response to accidental radiation
exposure can be managed better.
A
dose-response relationships
18
: interaction at the atomic level
Effects of X-rays on Human
19
Caused: deposition of energy in tissue
Molecular Change
20
Radiation response occurs within minutes or
days after radiation exposure
Early Effect of Radiation
21
Radiation response that is not observe for 6
months or longer after radiation exposure
Late Effect of Radiation
22
it determines the character & degree of the
radiation interaction that occurs
Atomic Composition
23
First named the cell as the biologic building
block
Robert Hooke (1665)
24
memorize the Atomic Composition
search the table
25
Accurately described a living cell on the
basis of his microscopic observations
Anton Van Leeuwenhoek (1673)
25
Showed that cells are the basic functional
units in all plants & animals
Schneider & Schwann (1838)
26
Described the molecular structure of
deoxyribonucleic acid (DNA) as genetic
substance of the cell
Watson & Crick (1953)
26
Result: precise mapping of 40,000 human
genes
Human Genope Project (2000)
27
Human Genope Project (2000)
Result: precise mapping of how many human
genes
40,000 human
genes
28
It defines the nature of radiation response
Molecular & Tissue Composition
28
Molecular & Tissue Composition
Macromolecules: contains what
proteins, lipids (fats),
carbohydrates (sugars & starches) & nucleic
acids
29
Molecular & Tissue Composition
Principal Organic Molecules: contains what
proteins,
lipids & carbohydrates
30
memorize the tabel of MOLECULAR COMPOSITION OF THE BODY
....
31
Very large molecules that sometimes consist
of hundreds of thousands of atoms
Macromolecules
32
Life-supporting & contains carbon
Organic Molecule
33
The rarest molecule in the body
Nucleic Acid
34
Concentrated in the nucleus of a cell (DNA)
Nucleic Acid
35
The most critical & radiosensitive target
molecule
Nucleic Acid
36
The simplest & the most abundant molecular
constituent in the body
Water
37
Water
Important Role:
delivering energy to the
target molecules (contribute to radiation
effects)
38
The production of large molecules from
small
Anabolism
39
Catabolism & anabolism
Metabolism
40
Long chain macromolecules that consist of a
linear sequence of amino acids connected by
peptide bonds
Proteins
41
Water
Composition: t
two atoms of Hydrogen & 1 atom of Oxygen
42
water
Functions:
- Provide some form & shape
- Assist in maintaining body temperature
- Enter into some biochemical
reactions
42
The state of equilibrium among tissue & organs
Homeostasis
43
Breaking down into smaller units of
macromolecules
Catabolism
44
Essential for proper metabolism
Trace Elements & Inorganic Salts
45
Proteins
Protein Synthesis:
used 22 amino acids
46
Proteins
functions:
- Provide structure & support
(muscles)
o Enzymes, hormones & antibodies
47
Proteins
General Formula:
CnHnOnNnTn
47
Proteins
Linear Sequence/Arrangement:
AA—AA—AA—AA
48
The metabolic production of proteins
Protein Synthesis
48
Molecules that are necessary in small
quantities to allow a biochemical reaction to
continue, even though they do not directly
enter into the reaction
Enzymes
49
Molecules that exercise regulatory control
over some body functions
Hormones
50
They are produced & secreted by endocrine
glands
hormones
51
Organic macromolecules composed solely
of carbon, hydrogen, & oxygen
Lipids
52
Two Types of Molecules:
o Glycerol – 1 molecule
o Fatty acid – 3 molecules
53
Carbohydrates
Sugars:
monosaccharides & disaccharides
53
carnohydrates It is also called
It is also called saccharides
54
To provide fuel for cell metabolism
Carbohydrates
54
Carbohydrates
Function:
Provide shape & stability
55
The ultimate molecule that fuels the body
Glucose
55
A simple sugar
Glucose
55
Glucose
Chemical Formula:
C6H12O6
55
Ordinary table sugar
Sucrose
56
Sucrose
Chemical Formula:
Chemical Formula: C12H22O11
57
A human polysaccharide
It stored in tissues of the body
It used only when quantities of the simple
sugar (glucose) are inadequate
Glycogen
57
Plant starches & animal glycogen
Polysaccharides
58
It contains all the hereditary information that
represents a cell or whole individual (germ
cell)
dna
59
is the radiation-sensitive target molecule!
DNA
60
Attached to each deoxyribose molecule
Nitrogenous Organic Bases
61
base bonding is possible in DNA!
Only adenine-thymine & cytosine-guanine
62
The base sugar-phosphate combination
Nucleotide
63
THE HUMAN CELL
Two Major Structures
Nucleus & Cytoplasm
64
The center of the cell
Nucleus
65
A rounded structure that is attached to the
nuclear membrane
It contained most of the RNA
Nucleolus
66
A critical cellular function necessary for
survival
Protein Synthesis
66
Absorbs all nutrients through the cell
membrane
Cell Function
67
The portion of the cell between mitotic
events
The period of growth of the cell between
divisions
Interphase
67
Human Cells
Lethal Dose:
< 100 rad (1 Gyt)
68
The bulk of the cell
It contains great quantities of all molecular
components except DNA
Cytoplasm
68
the act of a single cell or group of cells to
reproduce & multiply in number
Cell Proliferation
68
A double-walled structure that at some
locations is connected to the endoplasmic
reticulum
Nuclear Membrane
68
The nucleus swells
Prophase
68
Process of somatic cell division wherein a
parent cell divides to form two
Mitosis
69
The engine of the cell
Mitochondria
70
a channel or series or channels that allows
the nucleus to communicate with the
cytoplasm
Endoplasmic Reticulum
71
Process that occurs during meiosis wherein
chromatids exchange chromosomal material
Crossover
72
memorize TISSUE COMPOSITION OF THE BODY
....
73
memoruze RESPONSE TO RADIATION IS RELATED
TO CELL TYPE
////
74
are more sensitive to radiation than
mature cells!
Stem cells
75
mwmoerize RELATIVE RADIOSENSITIVITY OF TISSUES & ORGANS BASED ON
CLINICAL RADIATION ONCOLOGISTS
/////
76
Factor used in radiation protection that
accounts for differences in biologic
effectiveness between different radiations
Radiation Weighting Factor (WR)
77
Ratio of the dose of standard radiation
necessary to produce a given effect to the
dose of test radiation needed for the same
effect
Relative Biologic Effectiveness (RBE)
78
The dose is delivered continuously but at a
lower dose rate
Protraction
79
A mathematical & graphic function that
relates radiation dose to observed response
Dose-Response Relationship
80
Theorized & observed that radiosensitivity
was a function of metabolic state of tissue
being irradiated
Jean Bergonie & Louis Tribondeau (1906)
80
A measure of the rate at which energy is
transferred from ionizing radiation to soft
tissue
Linear Energy Transfer (LET)
81
The standard radiation by convention
Range: 200-250 kVp
It was used in radiation oncology
Orthovoltage X-rays
82
The dose is delivered at the same dose in
equal portions at regular intervals
It reduces the effect
Fractionation
83
Ratio of the dose necessary to produce a
given effect under anoxic conditions to the
dose necessary to produce the same effect
under aerobic conditions
Oxygen Enhancement Ratio (OER)
84
It occurs when the cell dies before
replicating
Interphase Death
85
It is due to a repair mechanism inherent in
the biochemistry of the cell
Intracellular Repair
86
Irradiation outside of the cell or body
In Vitro
87
Irradiation with the cell or body
In Vivo
88
The breakage of the backbone of the ling-
chain macromolecules
Main-Chain Scission
89
Process of forming a protein molecule from
messenger RNA
translation
89
Process of constructing mRNA
Transcription
90
Any change that results in the impairment or
loss of function at the point of a single
chemical bond
Not detectable
Point Lesion
90
are cautious and
assume that even SMALL radiation doses are harmful? t or f
true
91
It represents the principal radiation
interaction in the body
Irradiation of Water
92
defines the
nature of the radiation response.
The molecular and tissue composition
92
how many percentage of the body consists of hydrogen and oxygen?
85%
92
Radiation interaction at the atomic level results in
molecular change, which can produce a cell that is deficient in terms of normal growth and metabolism.
Cell Theory
92
who accurately described
a living cell on the basis of his microscopic observations.
Anton van Leeuwenhoek
92
It was more than 100 years later, however, in 1838,
that Schneider and Schwann showed conclusively that
in all plants and animals, cells are the basic functional
units. This is WHAT
cell theory
93
Process of side spurs created by irradiation
& attached to a neighboring macromolecules
or to another segment of the same molecule
Cross-Linking
94
It was more than how many years later, however, in 1838,
that Schneider and Schwann showed conclusively that
in all plants and animals, cells are the basic functional
units. This is the cell theory.
100
95
It was more than 100 years later, however, in what year,
that Schneider and Schwann showed conclusively that
in all plants and animals, cells are the basic functional
units. This is the cell theory.
1838
96
what year and who are those person that the description of the
molecular structure of deoxyribonucleic acid (DNA) as the genetic substance of the cell was a major accom-
plishment.
The 1953 Watson and Crick
97
Precise mapping of the how many human genes, which was the result of the Human Genome Project completed in the year 2000, promises exceptional solutions to the detection and management of human disease.
40, 000
97
Precise mapping of the 40,000 human genes, which was the result of the WHAT that completed in the year 2000, promises exceptional solutions to the detection and management of human disease.
Human Genome Project
98
Precise mapping of the 40,000 human genes, which was the result of the Human Genome Project completed in the what year, promises exceptional solutions to the detection and management of human disease.
2000
99
what is also imaging is already making significant con-
tributions to human health.
Molecular imaging
100
Five principal types of molecules are found in the human
body (Table 29.4). Four of these molecules— what are those
proteins,
lipids (fats), carbohydrates (sugars and starches), and
nucleic acids
101
Five principal types of molecules are found in the human
body (Table 29.4). Four of these molecules—proteins,
lipids (fats), carbohydrates (sugars and starches), and
nucleic acids—are what
macromolecules.
102
are very large molecules that
sometimes consist of hundreds of thousands of
atoms.
macromolecules
103
Proteins, lipids, and carbohydrates are the principal
classes of what
organic molecules.
104
is
life supporting and contains carbon.
An organic molecule
104
One of the rarest
molecules—
DNA—
105
is considered to be the most critical and
radiosensitive target molecule.
DNA
106
is the most abundant molecule in the body, and
it is the simplest.
Water
107
Water consists of what
two atoms of hydrogen and one
atom of oxygen (H2O)
107
t or f Humans are not basically made of
structured water, because of the muscle itself that is being irradiated
false
108
are long-chain macromole-
cules that consist of a linear sequence of amino acids con-
nected by peptide bonds.
Proteins
109
Proteins are long-chain macromole-
cules that consist of a linear sequence of WHAT con-
nected by peptide bonds.
amino acids
110
Proteins are long-chain macromole-
cules that consist of a linear sequence of amino acids con-
nected by what
peptide bonds.
111
how many amino acids are used in protein synthesis, the metabolic production of proteins.
22
112
Twenty-two amino acids are used in what, the metabolic production of proteins.
protein synthesis
113
what is Protein =
Protein = AA * AA * AA * AA ...
114
Protein = AA * AA * AA * AA ...
where AA is what
amino acid
114
Protein = AA * AA * AA * AA ...
where AA is the amino acid and * is the
peptide bond
115
In general, __of the mass of a protein molecule is carbon, __ oxygen, 1__ nitrogen,
__ hydrogen, and ___ other elements.
In general, 50% of the mass of a protein molecule is carbon, 20% oxygen, 17% nitrogen,
7% hydrogen, and 6% other elements.
116
Proteins also function as what
enzymes,
hormones, and antibodies.
116
The creation of the peptide
bond requires what
the removal of a molecule of water.
116
are molecules that are necessary in small
quantities to allow a biochemical reaction to continue
even though they do not directly enter into the reaction.
Enzymes
116
The
molecular configuration of an antibody may be precise
and designed for attacking a particular type of invasive
or infectious agent, called what
antigen.
117
In general, lipids
are composed of two types of smaller molecules— what are those
glycerol
and fatty acid.
117
also serve as fuel for the body by providing
energy stores.
Lipids
117
are organic macromolecules composed solely of
carbon, hydrogen, and oxygen.
Lipids
117
the metabolic production of proteins.
protein synthesis
117
Lipids
often are concentrated just under the skin and serve as
WHAT from the environment. Penguins,
thermal insulator
118
, similar to lipids, are composed solely
of carbon, hydrogen, and oxygen, but their structure is
different
Carbohydrates
119
It is more difficult, however, to extract
energy from lipids than from the other major fuel
source, carbohydrates; this relationship, of course, is
associated with one of the major dilemmas in modern
nutrition
obesity.
120
are large
and include plant starches and animal glycogen.
Polysaccharides
121
The chief function of carbohydrates in the human
body is to
provide fuel for cell metabolism.
122
is the ultimate molecule that fuels the human
body.
Glucose
123
Two principal nucleic acids are important to human
metabolism:
DNA and ribonucleic acid (RNA). Located
124
Located
principally in the nucleus of the cell and serves as the
command and control molecule for cell function.
dna
125
is the radiation-sensitive target molecule.
DNA
126
Attached to each deoxyribose molecule is one of four
different nitrogen-containing or nitrogenous organic
bases:
adenine, guanine, thymine, or cytosine.
127
Adenine
and guanine are what;
purines;
128
what are the
pyrimidines.
thymine and cytosine
129
The base sugar–phosphate combination is called whAT and are strung together in
one long-chain macromolecule.
nucleotide
130
base bonding is possible in DNA.
Only adenine–thymine and cytosine–guanine
131
DNA or RNA, the
sugar component is
ribose
132
The two major structures of the cell are the
the nucleus
and the cytoplasm.
133
Most of the RNA is contained in a rounded struc-
ture, the what.
the nucleolus.
134
The nucleolus often is attached to the nuclear membrane, a double-walled structure that at some locations is connected to the what
endoplasmic reticu-
lum.
134
often is attached to the nuclear membrane, a double-walled structure that at some locations is connected to the endoplasmic reticu-
lum.
The nucleolus
135
The principal molecular component
of the nucleus andthe genetic material of the cell.
DNA
136
The nucleus also contains some
RNA, protein, and water.
137
is a
channel or a series of channels that allows the nucleus to
communicate with the cytoplasm.
The endoplasmic reticulum
138
are digested in the mitochondria to produce energy for the cell.
Macromolecules
139
The small pea-like sacs are
. The
contain enzymes capable of digesting cellular fragments
and sometimes the cell itself.
help control
intracellular contaminants.
lysosomes
139
provide structure and form for the human cell and its components.
cellular membranes
140
When the critical macromolecular cellular components are irradiated by themselves, a dose of approximately how many kgyt? is required to produce a measurable change in any physical characteristic of the molecule.
10 kGyt
141
required to produce a measurable change in any physical characteristic of the molecule.
10 kgyt
141
is a good example of a critical func-
tion necessary for cell survival
Protein synthesis
141
A series of 3 base pairs, called a WHAT,
identifies 1 of the 22 human amino acids
available for protein synthesis.
codon
142
identifies 1 of the 22 human amino acids
available for protein synthesis.
codon
142
is the act of a single cell or
group of cells reproducing and multiplying in
number.
Cell proliferation
143
The small, dot-like structures are .
are the site of protein synthesis and therefore are essential to normal cellular function.
are scattered throughout the cytoplasm and the endoplas-
mic reticulum.
ribosomes
144
The human body consists of two general types of
cells
somatic cells and genetic cells. The
145
When somatic cells divide and proliferate, they
undergo what.
mitosis
146
When somatic cells divide and proliferate, they
undergo mitosis. Genetic cells undergo called
meiosis
147
Geneticists consider only two phases of the cell cycle:
mitosis (M) and interphase.
148
Mitosis, the division phase, is characterized by four subphases:
prophase, metaphase, anaphase, and telo-
phase.
149
The portion of the cell cycle between mitotic events is called
Interphase
150
is the period of
growth of the cell between divisions.
Interphase
150
Cell biologists usually identify four phases of the cell
cycle:
M, G1, S, and G2.
151
in cell growth
between M and S is G1.
the gap
152
G1 is what
G1 is the pre-DNA synthesis phase.
153
The DNA synthesis phase is
The DNA synthesis phase is S.
154
is the post-DNA synthesis gap of cell
growth.
The G2 phase
154
During what phase, the nucleus swells and the DNA
becomes more prominent and begins to take structural
form.
During prophase
155
at what phase, the chromosomes appear and are
lined up along the equator of the nucleus.
metaphase
156
what phase that mitosis can be stopped and chromo-
somes can be studied carefully under the microscope.
metaphase
157
what damage is
analyzed during metaphase.
Radiation-induced chromosome damage
158
is characterized by the splitting of each
chromosome at the centromere, so that a centromere and
two chromatids are connected by a fiber to the poles of
the nucleus.
Anaphase
158
two chromatids are connected by a fiber to the poles of
the nucleus. These poles are called what, and the fibers
are called what.
spindle/spindle fibers
159
The final segment of mitosis, WHat phase, is character-
ized by the disappearance of structural chromosomes into a mass of DNA and the closing off of the nuclear
membrane, like a dumbbell, into two nuclei.
telophase
159
Genetic material can change during the division process
of genetic cells, which is called WHAT
meiosis.
160
is the process whereby genetic cells
undergo reduction division.
Meiosis
160
Meiosis is the process whereby genetic cells
undergo WHAT
reduction division.
161
some chromosomal material is
exchanged among chromatids through a process called
crossing over
161
results in changes in genetic
constitution and changes in inheritable traits.
Crossing over
162
Immature cells are called
stem cells.
162
are more sensitive to radiation than
mature cells.
Stem cells
163
are least radiosensitive.
nerve cells
164
is a measure of the rate at
which energy is transferred from ionizing radiation to
soft tissue.
Linear energy transfer (LET)
165
Linear energy transfer (LET) is a measure of the rate at
which energy is transferred from ionizing radiation to
soft tissue. It is another method of expressing radiation
energy or radiation quality and determining the value of
what used in radiation
protection
radiation weighting factor (WR)
166
is expressed in units of
kiloelectron volt of energy transferred per micrometer of
track length in soft tissue (keV / μm).
LET
167
LET is expressed in units of
WHAT
units of
kiloelectron volt of energy transferred per micrometer of
track length in soft tissue (keV / μm).
167
The LET of diagnostic x-rays is approximately
how many keV/μm.
3 keV/μm.
168
is the ratio of radiation dose from a stan-
dard radiation necessary to produce a given effect to the dose from a test radiation to produce the same effect.
RBE
169
is the ratio of a standard radiation dose to
produce the same response as that following a test radiation dose.
RBE
170
The standard radiation, by convention, is orthovolt-
age x-radiation in the range of WHAT
200 to 250 kVp
170
The RBE of diagnostic x-rays is how many
1.
171
Tissue is more sensitive to radiation when irradiated in the oxygenated state than when irradiated under anoxic
(without oxygen) or hypoxic (low-oxygen) conditions.
This characteristic of tissue radiation response is called
the oxygen effect and is described numerically by the
oxygen enhancement ratio (OER).
171
is the ratio of the radiation dose necessary
to produce a given effect under anoxic tissue conditions to that required to produce the same effect under aero-
bic conditions.
The OER
172
is the ratio of radiation doses under anoxic
conditions to produce the same response as
that following irradiation under oxygenated
conditions.
oer
173
is conducted under conditions of full oxygenation.
tissue irradiation
173
has been used in radiation oncology in an attempt to enhance the radiosensitivity of nodular, avascular tumors, which are less radiosensitive than tumors with an adequate blood supply.
Hyperbaric (high-
pressure) oxygen
173
yes or no? it's okay for the diagnostic x-ray imaging is performed under
conditions of full oxygenation?
yes
173
If the radiation dose is not sufficient to kill the cell before its next division (interphase death), then given sufficient time, the cell will recover
from the WHAT it has sustained.
sublethal radiation damage
173
what phase death occurs when the cell dies
before replicating.
Interphase
174
Relationship C is sometimes called a WHAT radiation dose-
response relationship.
sigmoid type
175
can result in the stochastic radiation
effects observed at the whole-body level.
Point lesions
176
The fifth type of damage, the change or loss of a base, also destroys the triplet code and may not be reversible.
This type of radiation damage is a molecular lesion of the DNA. These molecular lesions are called WHAT , and they can be of minor or major importance to the cell.
point mutations
176
The final result of the radiolysis of water is the formation of an WHAT, H+ and OH−, and two free radicals, H* and OH*.
ion pair
177
The final result of the radiolysis of water is the formation of an ion pair, __ and __, and two free radicals, H* and OH*.
H+ and OH -
177
The final result of the radiolysis of water is the formation of an ion pair, H+ and OH−, and two free radicals, is what
H* and OH*.
178
is an uncharged molecule that
contains a single unpaired electron in the outer
shell.
A free radical
179
what , is considered to be the principal damaging product after the radiolysis of water.
The hydroperoxyl radical, along with hydrogen per-
oxide
180
When the ionizing event occurs on the target
molecule, WHAT
the effect of radiation is direct.
180
The principal effect of radiation on humans is
WHAT
indirect.
180
If the
ionizing event occurs with water and transfers that
energy to DNA, the event is said to be an
indirect effect.
181
for a cell to die after radiation exposure, its target molecule must be inactivated
target theory
181
is the target molecule.
dna
182
When radiation does interact with the target, a WHAT is said to have occurred.
hit
182
Hits occur through both
direct and indirect
effects.
182
Originally, the target theory was used to represent what
cell
lethality.
182
If normal cells
are planted individually in a Petri dish and are incubated
for 10 to 14 days, they divide many times and produce
a visible colony that consists of many cells. what is called?
cell cloning
183
The lethal effects of radiation are determined by WHAT, not cell death.
observing cell survival
183
The lethal effects of radiation are determined by observing cell survival, not by whta
cell death
184
what model applies to biologic targets, such as enzymes, viruses, and simple cells such as bacteria.
The single-
target, single-hit model
185
what model applies to more complicated biologic systems such as human cells.
The multitarget, single-hit model
186
when falling randomly, the probability that a square will become wet is governed by a statistical law called the
Poisson distribution.
187
is a measure of the radiosensitivity of the cell.
D37
187
A low D37 indicates a what
A low D37 indicates a highly radiosensitive cell,
187
A high D37 reveals what
radioresistance.
188
The model of cell survival just described is the
multi-
target, single-hit model.
188
called the mean lethal dose and is a con-
stant related to the radiosensitivity of the cell.
The D0
188
The D0 is called the WHAT and is a con-
stant related to the radiosensitivity of the cell.
mean lethal dose
188
A large D0 indicates
radioresistant cells
188
A small
D0 is characteristic of
radiosensitive cells.
188
The extrapolation number is also called the
target number.
188
is also called the target number.
The extrapolation number
189
When this type of experiment was first con-
ducted with human cells, the observed extrapolation number was
2
189
Subsequent experiments, however, have resulted in extrapolation numbers ranging from
2 to 12
190
is called the threshold dose.
DQ
190
The DQ is called the
threshold dose
190
It is a mea-
sure of the width of the shoulder of the multitarget, single-hit model and is related to the capacity of the
cell to recover from sublethal damage.
threshold dose.
190
A large DQ indicates that the cell can recover
readily from
sublethal radiation damage.
190
The shoulder of the graph of the multitarget, single-hit
model shows that for mammalian cells, some damage
must be accumulated before the cell dies. This accumu-
lated damage is called
sublethal damage.
190
For full recovery to occur, the time between such split doses must be at least as long as the cell generation time, how many hours
usually 24 hours.
190
is a measure of the capacity to accumulate
sublethal damage and the ability to recover from
sublethal damage.
DQ
190
When human cells replicate by mitosis, the average time from one mitosis to another is called
the cell-cycle
time.
190
Most human cells that are in a state of normal proliferation have cell-cycle times of approximately how many hours
approximately 24
hours.
190
Some specialized cells have cell-cycle times that
extend to hundreds of hours, and other cells, such as WHAT, do not normally replicate. Longer
neurons (nerve cells)
190
is the most time variable of cell phases.
G1
190
A randomly growing population of cells that are uniformly distributed in position throughout the cell cycle can be WHAT in various ways.
synchronized
191
Human cells are 1. most radiosensitive in what phase and 2. most radioresistant in what
Human cells are most radiosensitive in M and
most radioresistant in late S.
191
The next most sensitive
phase of the cell cycle occurs at the
G1–S transition.
191
The most resistant portion of the cell cycle is the
the late
S phase.
191
is related to radiosensitivity,
D0
191
for one condition of irradiation compared
with another is a measure of the effectiveness of the dose modifier, whether it is physical or biological.
ratio of D0
192
Irradiation of mammalian cells with high-LET
radiation follows the
follows the single-target, single-hit
model.
193
cells that with a high-LET
radiation follows the single-target, single-hit
model.
Irradiation of mammalian
193
t or f. The mean lethal dose after low-LET irradiation is
always greater than that after high-LET irradiation.
t
194
t or f. The mean lethal dose after low-LET irradiation is
always lesser than that after high-LET irradiation.
f
195
When anoxic cells are exposed, a
considerably how many dose is required to produce a given
effect.
higher dose
196
For a cell to
die after radiation exposure, the target molecule, DNA,
must be
inactivated.
197
The single-target, single-hit model applies to simple cells such as
bacteria.
198
A dose of this magnitude is rare in diagnostic
radiology.
early effect of radiation
exposure
198
To produce a radiation response in humans within
a few days to months, the dose must be substantial.
Such a response is called an
early effect of radiation
exposure.
199
was the only way to monitor x-ray workers for occupational radiation
exposure.
periodic blood examination
199
Deterministic radiation effects are those that exhibit
increasing severity with increasing radiation dose.
Furthermore, there is a dose threshold, and the dose-
response relationship is
nonlinear
199
always result in partial-
body exposure, which is less harmful than whole-
body exposure.
Diagnostic x-ray beams
200
The unfortunate incidents at Chernobyl
and Fukushima are notable exceptions. in both what year?
The unfortunate incidents at Chernobyl in April 1986
and Fukushima in March 2011 are notable exceptions.
200
how any people at Chernobyl experienced acute radia-
tion syndrome and died. A number of minor late effects have been observed.
30
200
how many died or seriousily exposed
exposed in the March 1979 incident at the nuclear
power reactor at Three Mile Island, Pennsylvania.
no one
200
No one died or was even seriously
exposed in what year incident at the nuclear
power reactor at Three Mile Island, Pennsylvania.
march 1979
200
No one died or was even seriously
exposed in the March 1979 incident at the nuclear
power reactor at?
Three Mile Island, Pennsylvania.
201
No acute lethality was observed at the tsunami-
induced meltdown of three nuclear reactors at
Fukushima, Japan.
201
t or f. Employment in the nuclear power industry is a
safe occupation.
t
201
No acute lethality was observed at the tsunami-
induced meltdown of three nuclear reactors at Fukushima, Japan. However, WHAT quantities to the environment caused the evacuation of more than 150,000 neighboring residents.
the dispersal of TBq (tera-
becquerel)
202
t or f. Employment in the nuclear power industry is not a consider as a
safe occupation.
f
202
The sequence of events that follow high-level radia-
tion exposure leading to death within days or weeks is called the
acute radiation syndrome.
203
are those that exhibit increasing severity with increasing radiation dose.
Deterministic radiation effects
204
At radiation doses how many gyt? to the total body, signs and symptoms of radiation sickness may appear within minutes to hours.
above approximately 1 Gyt
204
follow lower expo-
sures and require a longer time for death to occur.
Hematologic death and GI death
204
CNS death requires radiation doses
in how any gyt and results in death within hours.
> 50 Gyt
204
consists of acute clinical symptoms that occur within hours of exposure and continue for up
to a day or two.
prodromal period
205
what do you called After the prodromal period has ended,
there may be a period, during which the subject is
free of visible effects.
latent period
206
At radiation doses above approximately 1 Gyt delivered to the total body, signs and symptoms of radiation sickness may appear within
within minutes to hours.
206
The symptoms of early radiation sickness in prodromal period most often take the form of
what
nausea, vomiting, diarrhea, and a reduction in the white blood cells of the peripheral blood (leukopenia).
206
The immediate response of radiation sickness is
prodromal period.
206
death requires radiation doses in excess of 50 Gyt and results in death within hours.
cns
207
The prodromal period may last from a
few hours to
a couple of days.
207
The prodromal period may last from a few hours to
a couple of days. The severity of the symptoms is dose
related; at doses in
> 10 gyt
208
The severity of the symptoms is dose
related; at doses in excess of 10 Gyt, symptoms can be
violent
209
At still higher doses, the duration of the pro-
dromal syndrome becomes _______ until it is difficult to separate the prodromal syndrome from the period of
manifest illness.
shorter
210
At still higher doses, the duration of the prodromal syndrome becomes shorter until it is difficult to separate the prodromal syndrome from the period of what
manifest illness.
211
After the prodromal period, the period of initial radiation sickness, a period of apparent well-being occurs, which is called the
latent period.
212
The latent period
extends from
hours or less (at doses in excess of 50 Gyt) to weeks (at doses from 1 to 5 Gyt).
213
is the time after radiation
exposure during which there is no sign of
radiation sickness.
The latent period
214
The latent period is the time after radiation
exposure during which there is what
no sign of
radiation sickness.
215
The latent period is sometimes mistakenly thought to indicate an what
early recovery from a moderate radiation
dose.
215
is sometimes mistakenly thought
to indicate an early recovery from a moderate radiation
dose.
The latent period
215
Radiation doses in the range of WHAT produce the hematologic syndrome. The
approximately 2 to
10 Gyt
215
The patient initially experiences mild symptoms of the prodromal syndrome, which appear in a matter of a
a few hours and
may persist for several days.
216
The latent period that follows can extend as long as how many weeks and is characterized by a general feeling of well-
ness.
4 weeks
216
is characterized by
possible vomiting, mild diarrhea, malaise, lethargy, and
fever.
The period of manifest illness
217
The period of manifest illness is characterized by
possible vomiting, mild diarrhea, malaise, lethargy, and
fever.
218
in The period of manifest, If the dose is not
lethal, recovery begins in 2 to 4 weeks, but as long as how many months may be required for full recovery.
6 months
218
Radiation doses of how many Gyt result in gastrointestinal (GI) syndrome.
approximately 10 to 50 Gyt
218
in The period of manifest, If the dose is not
lethal, recovery begins in how many weeks, but as long as 6
months may be required for full recovery.
2 to 4 weeks
219
The prodromal symp-
toms of vomiting and diarrhea occur within
within hours of exposure and persist for hours to as long as a day.
220
A
latent period of how many days follows, during which no
symptoms are present.
3 to 5 days
221
occurs principally because of severe
damage to the cells lining the intestines.
GI death
222
are normally in a rapid state of proliferation and are continuously being replaced by new cells.
Intestinal cells
223
Radiation exposure kills the most sensitive cells—
what cells
stem cells.
223
Intestinal cells are normally in a rapid state of pro-
liferation and are continuously being replaced by new cells. The turnover time for this cell renewal system is
normally how many days
3 to 5 days
224
experimental animals are irradiated with varying
doses of radiation from
1 to 10 Gyt,
225
At the lower dose of approximately _ Gyt, no one is expected to die. Above approximately _ Gyt, all those irradiated die unless vigorous medical support is available. Above __ Gyt, even vigorous medical support does not prevent death.
At the lower dose of approximately 1 Gyt, no one is expected to die. Above approximately 6 Gyt, all those irradiated die unless vigorous medical support is available. Above 10 Gyt, even vigorous medical support does not prevent death.
225
The LD50/60 is the whole-body radiation dose that
causes 50% of irradiated subjects to die within
how many days.
60 days
225
Acute radiation lethality follows a
nonlinear,
threshold dose-response relationship.
226
If death is to occur, it usually happens within 60 days of exposure. Acute radiation lethality is measured quantitatively by the what, which is approximately 3.5 Gyt for humans.
LD50/60
226
If death is to occur, it usually happens within 60 days of exposure. Acute radiation lethality is measured quantitatively by the LD50/60, which is how many Gyt for humans.
approximately 3.5 Gyt for humans.
227
After a radiation dose in excess of approximately 50
Gyt or higher is received, a series of signs and symptoms
occur that lead to death within a matter of hours to days.
This is the .
cns syndrome
227
After a radiation dose in how many gyt is received, a series of signs and symptoms
occur that lead to death within a matter of hours to days.
This is the central nervous system (CNS) syndrome.
approximately > 50
Gyt or higher
227
The ultimate cause of death in CNS syndrome is
elevated fluid content of the brain.
227
If death is to occur, it usually happens within how many days of exposure. Acute radiation lethality is measured quantitatively by the LD50/60, which is approximately 3.5 Gyt for humans.
60
227
is the whole-body radiation dose that
causes 50% of irradiated subjects to die within
60 days.
The LD50/60
227
The LD50/60 is the whole-body radiation dose that
causes of how many % of irradiated subjects to die within
60 days.
50%
227
As the whole-body radiation dose increases, the average
time between exposure and death decreases. This time is
known as the
mean survival time.
228
is
dose dependent with the hematologic syndrome.
Mean survival time
229
In the dose range associated with GI syndrome, how-
ever, the mean survival time remains relatively constant
at how many days
at 4 days.
230
With larger doses, those associated with CNS syndrome, the mean survival time is again dose depen-
dent, varying from approximately how many
3 days to a matter of hours.
231
is the shrinkage of an organ or tissue
caused by cell death.
Atrophy
232
All deterministic radiation responses follow a a what dose-response relationship.
threshold-type
233
When that threshold
dose has been exceeded, the severity of the response
increases with increasing dose, in a what
nonlinear fashion.
233
Almost 50% of the cells lining the intestine are replaced
every day, but skin cells are replaced at the rate of only
how many percent per day.
approximately 2% per day.
234
are the stem cells that mature as they migrate
to the surface of the epidermis.
Basal cells
235
Basal cells are the WHAT that mature as they migrate
to the surface of the epidermis.
stem cells
236
Damage to basal cells results in the WHAT of radiation injury to the skin.
earliest
manifestation
237
In earlier times, the tolerance of the patient’s skin
determined the limitations of radiation oncology with
orthovoltage x-rays (200 to 300 kVp x-rays
238
is known
as clinical tolerance for radiation oncology.
Moist desquamation
239
was perhaps the first observed biologic
response to radiation exposure
Erythema
239
Analysis of persons irradiated therapeutically with superficial x-rays has shown that the skin erythema dose required
to affect 50% of those irradiated is about how many gyt
5 Gyt.
240
For many years, soft x-rays (10–20 kVp), called WHAT, were used as the treatment of choice for persons with skin diseases, such as ringworm (tinea capitis).
Grenz rays
241
For many years, soft x-rays (10–20 kVp), called Grenz rays, were used as the treatment of choice for persons with skin diseases, such as
ringworm (tinea capitis).
242
, which is common in chil-
dren, was successfully treated by Grenz radiation;
Tinea capitis
243
Tinea capitis of the scalp, which is common in chil-
dren, was successfully treated by ;
Grenz radiation;
244
Tinea capitis of the scalp, which is common in chil-
dren, was successfully treated by Grenz radiation; unfor-
tunately, the patient’s hair would fall out for weeks or
even months. Sometimes an unnecessarily high dose of
Grenz rays resulted in
permanent epilation.
244
are critically important target organs.
Human gonads
245
Human gonads are critically important target organs.
As an example of local tissue effects, they are particu-
larly sensitive to radiation. Responses to doses as low
as how many mGyt have been observed.
100 mGyt have been observed.
246
most radiosensitive cells in male and female germ cells
spermatogonia and mature follicle
247
Ovaries and testes produce WHATwhich mature into ovum and
sperm, respectively.
oogonia and
spermatogonia
248
are produced by both ovaries and testes, but they develop from the stem cell phase to the mature
cell phase at different rates and at different times.
Germ cells
249
Germ cells are produced by both ovaries and testes,
but they develop from the stem cell phase to the mature
cell phase at different rates and at different times. This
process of development is called
gametogenesis.
249
The stem cells of the ovaries are the WHAT, and
they multiply in number only before birth during fetal
life.
oogonia
250
During late fetal life, many WHAT grow
to encapsulate the oogonia, which become oocytes.
primordial follicles
251
During late fetal life, many primordial follicles grow
to encapsulate the oogonia, which become WHAT
oocytes
252
Commencing at puberty, the follicles rupture with
regularity, ejecting a mature germ cell, the WHAT.
ovum
252
Commencing at puberty, the follicles rupture with
regularity, ejecting a mature germ cell, the ovum. Only
how many such ova are available for fertilization (num-
ber of years of menstruation times 13 per year).
Only 400 to 500 such ova
253
The male stem cell is the WHAT, which
matures into the spermatocyte. The spermatocyte in
turn multiplies and develops into a spermatid, which
finally differentiates into the functionally mature germ
cell, the spermatozoa or sperm. The maturation process
from stem cell to spermatozoa requires 3 to 5 weeks.
spermatogonia
254
The male stem cell is the spermatogonia, which
matures into the WHAT.
spermatocyte
255
The spermatocyte in
turn multiplies and develops into a WHAT, which
finally differentiates into the functionally mature germ
cell, the spermatozoa or sperm. The maturation process
from stem cell to spermatozoa requires 3 to 5 weeks.
spermatid
255
The male stem cell is the spermatogonia, which
matures into the spermatocyte. The spermatocyte in
turn multiplies and develops into a spermatid, which
finally differentiates into the functionally mature germ
cell, the WHAT. The maturation process
from stem cell to spermatozoa requires 3 to 5 weeks.
spermatozoa or sperm
256
The male stem cell is the spermatogonia, which
matures into the spermatocyte. The spermatocyte in
turn multiplies and develops into a spermatid, which
finally differentiates into the functionally mature germ
cell, the spermatozoa or sperm. The maturation process
from stem cell to spermatozoa requires how many weeks
3 to 5 weeks
257
The most radiosensitive cell during female germ
cell development is the oocyte in the
mature
follicle.
258
At fetal life and in early childhood, the ovaries
are especially radiosensitive. They decline in radiosensi-
tivity, reaching a minimum in the age range of how many years, and then increase continually with age.
20 to 30 years
259
Doses as low as how any mGyt may delay or suppress
menstruation in a mature female.
100 mGyt
260
A dose of approxi-
mately how many Gyt produces temporary infertility;
2 Gyt
261
approxi-
mately how many Gyt to the ovaries results in permanent sterility.
5 Gyt
262
Even moderate doses,
such as how many mGyt, have been associated with
measurable increases in genetic mutations.
200-500 mgyt
263
signify the most sensi-
tive phase in the gametogenesis of the spermatozoa.
The spermatogonial stem cells
263
Radiation doses as low as how many mGyt can reduce the
number of spermatozoa
100 mGyt
264
how many gray/s produces temporary infertility, which
commences approximately 2 months after irradiation
and persists for up to 12 months.
2
264
how many gray/s to the testes
produces permanent sterility. Even after doses sufficient
to produce permanent sterility, the male patient nor-
mally retains his ability to engage in sexual intercourse.
5
264
is a self-renewing system.
Male gametogenesis
265
After testicular irradiation of doses exceeding approx-
imately 100 mGyt, the male patient should refrain from
procreation for how many months until all cells that were in
the spermatogonial and post-spermatogonial stages at
the time of irradiation have matured and disappeared.
2 to 4
265
is a periodic blood
examination recommended as a feature of any
current radiation protection program.
Under no circumstances
265
All cells of the hemopoietic system develop from
a single type of stem cell (Fig. 33.7). This stem cell is
called a WHAT because it can develop
into several different types of mature cells.
pluripotential stem cell
265
The products of bone marrow stem cells are WHAT (those involved in the immune response),
lymphocytes
265
scavenger type of cells used to fight bacteria),
granulocytes
265
also called platelets and involved in the
clotting of blood to prevent hemorrhage),
thrombocytes
265
red blood cells that are the transportation agents
for oxygen).
erythrocytes
265
While in the bone marrow, the cells proliferate in
number, differentiate in function, and mature. Developing granulocytes and erythrocytes spend about how many days in the bone marrow.
8 to 10
266
Thrombocytes have a lifetime
of approximately how many days in the bone marrow.
approximately 5 days
266
are produced over varying times and
have varying lifetimes in the peripheral blood.
Lymphocytes
266
In the peripheral blood, granu-
locytes have a lifetime of only a how many days
couple of days
266
In the peripheral blood, Thrombocytes have a lifetime of approximately how many weeks
1 week
266
In the peripheral blood, erythrocytes have a lifetime of how many months.
nearly 4 months
267
therefore, is another exam-
ple of a cell renewal system.
The hemopoietic system
268
The lymphocytes and the spermatogonia are the
most
most radiosensitive cells in the body.
269
Granulocytes experience a rapid rise in number
granulocytosis)
270
a slower decrease in number of granulocytes
(granulocytopenia).
271
Granulocytes experience a rapid rise in number
(granulocytosis) followed first by a rapid decrease and
then a slower decrease in number (granulocytopenia).
If the radiation dose is moderate, then an abortive rise in granulocyte count may occur how many days after
irradiation.
15 to 20
272
Minimum granulocyte and thrombocytes levels are reached
approximately how many days after irradiation
30 days
273
Minimum granulocyte and thrombocytes levels are reached
approximately 30 days after irradiation. Recovery, if it
is to occur, takes approximately how many months.
2 months.
273
are less sensitive than the other blood
cells, apparently because of their very long lifetime in
the peripheral blood.
Erythrocytes
274
Erythrocytes are less sensitive than the other blood
cells, apparently because of their very long lifetime in
the peripheral blood. Injury to these cells is not appar-
ent for a matter of weeks. Total recovery may take how many year sor mnth
Total recovery may take 6 months to a year.
274
is the study of the genetics of cells,
particularly cell chromosomes.
Cytogenetics
274
A technique developed in the early 1950s contributed
enormously to human genetic analysis and radiation
genetics.
CYTOGENETIC EFFECTS
274
The technique calls for a culture of human cells
to be prepared and treated so that the chromosomes of
each cell can be easily observed and studied.
CYTOGENETIC EFFECTS
274
This has
resulted in many observations on radiation-induced
chromosome damage.
CYTOGENETIC EFFECTS
274
are most often used
for cytogenetic analysis, and these lymphocytes do not move into mitosis until stimulated in vitro by an appro-
priate laboratory technique.
Human peripheral lymphocytes
274
For certain types of cytogenetic analysis, photo-
graphs are taken and enlarged so that each chromosome
can be cut out like a paper doll and paired with its sister
into a chromosome map, which is called a
karyotype
274
Each cell has how many pairs of autosomes and one pair
of sex chromosomes—the female X chromosome
and the male Y chromosome.
22
275
When radiation interacts with chromosomes, the inter-
action can occur through direct or indirect effect. In either mode, these interactions result in a .
hit
275
The
breakage of a chromatid is called
chromatid deletion.
275
The chromosome aberration visualized at metaphase
consists of a chromosome with material missing from
the ends of two sister chromatids and two acentric
(without a centromere) fragments. These fragments are
called .
isochromatids.
275
The mechanism for the joining of chromatids depends on a
condition called WHAt that is radiation-induced and appears at the site of the severed chromosome.
stickiness
275
are multihit chromosome aberrations that require karyotypic analysis for detec-
tion
Reciprocal translocations
275
are considered to be the most significant in terms of later human response.
Multihit aberrations
275
Some laboratories use this as a
biologic radiation dosimeter.
cytogenetic analysis
275
After many years of scientific investigation, in wht year
the human genome was mapped. This was a worldwide
project involving many different laboratories. Humans
have about 35,000 genes distributed along the DNA of
the 46 chromosomes.
2000
275
After many years of scientific investigation, in 2000,
the human genome was mapped. This was a worldwide
project involving many different laboratories. Humans
have about how many genes distributed along the DNA of
the 46 chromosomes.
35,000 or 40,000
275
After many years of scientific investigation, in 2000,
the human genome was mapped. This was a worldwide
project involving many different laboratories. Humans
have about 35,000 genes distributed along the DNA of
the how many chromosomes.
46
276
After exposure to a high radiation dose, humans can
experience a response within a few days to a few weeks.
This immediate response is called a
deterministic effect.
277
Such early effects are deterministic because the severity
of response is dose related, there is a dose threshold, and
the dose-response relationship is .
non linear
278
The sequence of events that follows high-dose radia-
tion exposure leading to death within days or weeks is
called WHAT, which includes hema-
tologic syndrome, GI syndrome, and CNS syndrome.
These syndromes are dose related.
acute radiation syndrome
279
is the dose of radiation to the whole body
in which 50% of subjects will die within 60 days.
LD50/60
280
For
humans, this dose is estimated at how many Gyt.
3.5 Gyt.
281
The first manifestation of radiation injury to the skin is
damage is the
basal cells
282
Resultant skin damage occurs
as
erythema, desquamation, or epilation.
283
Radiation of the male testes can result in a reduction
of .
spermatozoa.
284
A dose of how many Gyt produces temporary
infertility.
2
285
A dose of how many Gyt to the testes produces permanent sterility.
5
286
In males as in females, the stem cell is the
most
most radiosensitive phase.
287
The study of chromosome damage from radiation
exposure is called
radiocytogenetics.
288
Chromosome dam-
age takes on the following different forms:
(a) chroma-
tid deletion, (b) dicentric chromosome aberration, and
(c) reciprocal translocations.
289
DETERMINISTIC EFFECTS of radiation exposure are produced by
high radiation doses.
289
Stochastic effects of radiation exposure are
the result of WHAT over a long period.
low doses delivered
290
t or f. The radiation exposures that we experience in diagnos-
tic radiology are high and of high LET;
f, low radiation and low let
290
The stochastic dose-response relationship is nonlinear r linear?
linear
290
Our radiation protection guides are based on
the stochastic effects of radiation is what
linear,
nonthreshold dose-response relationships.
291
Studies of large numbers of people exposed to a toxic
substance require considerable statistical analyses. Such
studies, called WHAT, are required when
the number of persons affected is small.
epidemiologic studies
291
This stochastic effect was observed many years ago
in radiologists and is called
radiodermatitis.
291
In what year , Ernest O. Lawrence of the University of Cali-
fornia developed the first cyclotron,
1932
291
In 1932, who developed the first cyclotron,
Ernest O. Lawrence
292
Radiation-induced cataracts occur on the
posterior pole of the lens.
293
The dose-response relationship for radiation-
induced cataracts is
nonlinear, threshold.
294
Consequently, precise dose-response relationships
are often not possible to formulate, and we therefore
resort to what
risk estimates.
295
There are three types of risk
estimates—
relative, excess, and attributable risk;
296
If one observes a large population for stochastic radiation effects without having any precise knowledge of the radiation dose to which they were exposed, then
the concept of WHAT is used.
relative risk
297
is
computed by comparing the number of persons in the
exposed population showing a given stochastic effect
with the number in an unexposed population who show
the same stochastic effect.
relative risk
298
A relative
risk of how many indicates that the frequency of a late response
is 50% higher in the irradiated population than in the
nonirradiated population.
1.5
298
Occasionally, an investigation results in the identifi-
cation of a relative risk of less than
1
298
The relative risk for radia-
tion-induced stochastic effects of particular importa nce
observed in human populations is in the range of what
1 to 2
299
This indicates that
the radiation exposed population receives some protec-
tive benefit, which is consistent with the theory of
radiation hormesis.
300
The theory of radiation hormesis suggests that are beneficial.
very low radiation doses
300
If at least two different dose levels are known, then it
may be possible to determine an
attributable risk factor.
301
is the metric most often used to
estimate patient radiation risk.
Attributable risk
302
usually begins with the development of
radiodermatitis.
skin cancer
302
Radiation-induced skin cancer follows a
threshold dose-response relationship.
302
Radiation-induced breast cancer exhibits a what
a linear,
nonthreshold dose-response relationship.
302
is an alpha-emitting radionuclide that
adsorbs on dust particles that lodge in the
alveolar spaces of the lung.
Radon
303
is that dose of radiation
that produces twice the frequency of genetic
mutations as would have been observed without
the radiation.
The doubling dose
303
is calculated
when the population’s radiation dose is not known.
Relative risk
303
determines the magnitude of the stochastic
effect as the difference between cases and control sub-
jects.
Excess risk
303
what risk is the most useful.
Attributable risk
cluster 1
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