279 terms

Ch. 6 and Ch. 2 Rad Bio (all sets combined)

X-rays are what form of ionizing radiation?
Which type of radiation originates from a radioactive nucleus?
CT scanning is now a major source of medical radiation exposure. T/F
Which interaction involves photons generally below 10keV?
A. Classical
B. Photoelectric
C. Compton
D. Photodisintegration
Interactions between higher energy photons and outer shell electrons of tissue atoms result in:
A. Classical
B. Compton
C. Photoelectric
D. Photodisintegration
Most of the scatter produced during radiography procedures results from which interactions?
A. Pair production
B. Compton
C. Photoelectric
D. Classical
Photoelectric absorption increases as the effective atomic number of matter increases. Which of the following has the highest atomic number?
A. Water
B. Bone
C. Soft tissue
D. Air
What is the ejected electron called in a photoelectric event?
A. Photodisintegration
B. Positron
C. Negatron
D. Photoelectron
Pair production
What interaction produces a positron and an electron?
A. Compton
B. Photoelectric
C. Photodisintegration
D. Pair production
Photodisintegration involves an interaction with the nucleus of a tissue atom. T/F
Molecular, cellular, organic
What are the three levels of biologic effects of radiation on humans?
A. Genetic, molecular, cellular
B. Organic, cellular, genetic
C. Molecular, genetic, organic
D. Molecular, cellular, organic
All of the above
In what part of the body can radiation absorption take place?
A. Skin
B. Bone
C. Organs
D. All of the above
Ion pair is created
What first happens when an x-ray interacts with and ionizes a molecule of water?
A. Metabolism
B. Anabolism
C. Ion pair is created
D. All of the above.
If HOH+ and an electron combine, which of the following occurs?
A. H20
B. OH*
C. H*
When water is ionized
When does radiolysis of water occur?
A. When water interacts with a macromolecule
B. When free radicals form toxic substances
C. When there is an interaction of radiation and human tissue
D. When water is ionized
Dense ionization
During irradiation, which of the following is more biologically dangerous?
A. Sparse ionization
B. Dense ionization
C. Both are equal
Which of the following is used as the standard for RBE?
A. Gamma
B. X-rays
C. Alpha
D. Beta
The presence of which of the following with low LET radiation will increase biologic damage?
A. Oxygen
B. Water
C. Heat
D. Soft tissue
Main-chain scission
Which subcellular effect may involve the breaking of one side rail of DNA?
A. Main-chain scission
B. Rung breakage
C. Loss of base
D. Separation of base
Instant death
Which cellular effect would result from 1000 gray over a very short period?
A. Instant death
B. Reproductive death
C. Apoptosis
D. Mitotic Death
According to the Law of Bergione and Tribondeau, cell radiosensitivity is directly proportional to the degree of differentiation.
During a typical exam the radiographer is most likely to be exposed to which of the following?

A. Classical
B. Compton
C. Pair Production
Which interaction results in excitation of the tissue atom but not ionization?

A. Compton
B. Photoelectric
C. Classical
D. Pair Production
Prior to 1990, medical sources of radiation contributed less than half of the total exposure to radiation in the United States. T/F
Photodisintegration is a common interaction in diagnostic radiography. T/F
pair production
1.02 MeV is required for which interaction?

A. Compton
B. Photoelectric
C. Pair Production
D. Photodisintegration
Which type of ionizing radiation is from the same family as microwaves?

A. Electromagnetic
B. Particulate
Which of the following involves an inner shell interaction and total absorption of the photon?

A. Classical
B. Compton
C. Photoelectric
D. Photodisintegration
Indirect Action
Most biologic damage from ionizing radiation is a result of which of the following?

A. Direct Action
B. Indirect Action
Direct Action
What is the process called when ionizing radiation transfers its energy to important macromolecules?

A. Direct Action
B. Indirect Action
The most serious change to a cell occurs when there is damage to which of the following?

A. Membrane
B. Nucleus
C.Cellular fluid
All of the Above
How do hydrogen and hydroxl radicals cause biologic damage?

A. They destroy chemical bonds
B. Hydroxl radicals can bond to form hydrogen peroxide
C. A hydrogen radical can interact with molecular oxygen forming hydroperoxyl radical
D. All of the above
Which of the following is the term used to describe the average energy deposited along the path of radiation?

A. Radiolysis of water
B. Compton scattering
Subcellular effect
Radiation interacting with DNA would be a

A. Cellular effect
B. Subcellular effect
Which of the following units is used to compare the different types of radiation with their biologic effects at different doses?

A. Seivert
C. Gray
Unit length of track (micron)
LET is the term used to describe the average energy deposited per

A. Gray
B. Dose
C. Ionization
D. Unit length of track (micron)
Mitotic death
Which of the following occurs after cell division?

A. Instant death
B. Reproductive death
C. Apoptosis
D. Mitotic death
According to the Law of Bergonie and Tribondeau, cell radiosensitivity is directly proportional to reproductive activity. T/F
Radiation can affect organic molecules in the same manner as inorganic molecules. T/F
Low LET radiation
OER is significant with

A. Low LET radiation
B. High LET radiation
C. Both are equal
Classical scattering
A process that is most likely to occur with low-energy x-rays (below 10 keV). When a photon from such an x-ray enters an atom, it does not have enough energy to knock out an electron and cause Compton scattering. Instead, the photon's energy causes a momentary state of excitation in the atom—a higher state of energy—which results in a secondary x-ray photon exiting the atom in a different direction but with the same energy. This process is also called Thompson, coherent, or unmodified, scattering.
The likelihood that certain types of interactions will occur in certain situations.
The process in which x-ray photons diverge from their original path in the x-ray beam and strike the film in random locations, producing an overall characteristic called film fog. It results from Compton and classical scattering.
A process that is most likely to occur with x-rays in the energy range of 30 to 50 keV. The photon of the x-ray knocks an electron out of the atom that it strikes, but not all of its energy is absorbed by the interaction. The x-ray photon exits the atom with lower energy in a different direction.
Characteristic photons
The result that occurs when an electron in an inner shell is knocked from its orbit by a projectile electron and another electron jumps down to fill its place, releasing an x-ray photon in this interaction equal in energy to the differences in electron binding energies.
The process that occurs when an incident x-ray photon is absorbed by the atom it strikes, and an electron is ejected from the inner shell of that atom.
Binding energy
The energy that holds protons and neutrons together in the nucleus through the force of attraction; the amount of energy needed to break up the nucleus.
The electron that is ejected during the process of photoelectric interaction.
Pair production
A process that occurs only with very high-energy x-ray photons. A photon with at least 1022 keV (or 1.02 MeV) of energy may penetrate the electron shells of the atom and reach the nucleus, where its energy is converted into the production of an electron and a positron.
A positively charged electron.
Annihilation event
A process that occurs after pair production. The positron that is created in pair production travels until it strikes an electron with which it interacts. The positron's and electron's mass disappears and is converted into two x-ray photons that radiate out of the atom.
The process that occurs when x-rays with extremely high energy (above 10 MeV) strike the nucleus of the atom and make it unstable. To become stable again, this nucleus ejects a nuclear particle, such as a proton, neutron, or alpha particle.
The smallest unit of a compound or element that can exist by itself and has the chemical properties of the compound or element.
Direct action
Process by which ionized particles directly transfer energy to important macromolecules, resulting in the breaking of chemical bonds, which may cause biologic damage.
Indirect action
Process by which ionized particles interact initially with noncritical molecules, which are then broken down into smaller molecules, producing both ions and free radicals that can recombine to form toxic substances, which can produce biologic damage.
Target theory
The scientific theory that each cell contains a key, or master, molecule and that cell death occurs only if the master molecule is destroyed as a result of exposure to ionizing radiation.
Free radical
An atom or molecule with a single electron in its outer shell.
Point lesion
Damage resulting when the chemical bonds of molecules are disrupted; also known as molecular lesion.
Hydrogen peroxide
H2O2, a toxic substance that is poisonous to human cells.
Hydroperoxyl radical
A combination that can occur during radiolysis of water. Hydrogen free radicals interact with molecular oxygen, creating a hydroperoxyl radical. Hydrogen peroxide and the hydroperoxyl radical are considered the primary causes of biologic damage resulting from radiolysis of water.
Radiolysis of water
The interaction of x-radiation with water.
Organic molecules
Life-supporting molecules; organic molecules that contain some carbon.
Protracted dose
A dose delivered continuously at a low-dose rate.
Fractionated dose
A radiation dose delivered over time in equal fractions.
Main-chain scission
The condition resulting from breakage of the thread or backbone of a long-chain molecule.
Cytoplasmic organelles
Small components of cells contained in the cytoplasm that perform many functions of the cell.
A nonmitotic or nondivision form of cell death that occurs when cells die without attempting division during the interphase portion of the cell life cycle; also called programmed cell death or interphase cell death.
Mitotic death
Damage to a cell's ability to reproduce, which occurs after a cell has divided at least once; also called genetic death.
Mitotic delay
A temporary delay in mitosis caused by radiation exposure.
radiation biology
branch of biology concerned with the effects of ionizing radiation on living systems
areas of study
includes: sequence of events, action of the living system, and injury to the living system
structure, composition, and function
Because we administer radiation ot humans for medical purposes, it is necessary that we have a basic understanding of cell ___, ___, and ___ as well as the adverse effects.
Ionizing radiation damages living systems by removing ___.
x-rays, gamma rays, alpha and beta particles, and protons
What is able to interact with orbital electrons?
Biologic damge begins with the ___ produced by various types of radiation.
What are the 3 important concepts that must be studied to understand the way ionizing radiation causes injury and how the effects my vary? (abbreviations)
Linear Energy Transfer (LET)
This states that ionizing radiation may interact with a material as it passes through and deposit energy.
Linear Energy Transfer (LET)
The average energy deposited per unit of length of path traveled.
X-rays and Gamma rays are forms of low/high LET radiation?
Low LET radiation
This is electromagnetic radiation that is sparsely ionizing, interacts randomly, doesn't give up all of it's energy quickly, and causes damage through indirect actions
Low LET radiation causes damage primarily through the formation of free radicals which is what type of action?
repair enzymes
What can usually reverse cellular damage caused by low LET?
Alpha particles are a form of low/high LET radiation?
High LET radiation
What includes particals that have substantial mass and charge that cause dense ionization and loses energy quickly?
Which form of LET is more destructive to biologic tissue?
The probability of an electron interacting with DNA rather than an alpha particle is ___
These particles have a low probability of interacting with DNA because they do not interact as often and they travel farther.
alpha particles
These particles have a high probability of interacting with DNA because they interact often and they do not travel far.
Biologic damage produced by radiation ___ as the LET of radiation increases.
Relative Biologic Effectiveness (RBE)
This describes the relative capabilities of radiation with differing LETs to produce a certain biologic reaction
Relative Biologic Effectiveness (RBE)
The ratio of the dose of reference radiation to the dose that is necessary to produce the same biologic reaction.
Dose in Gy from 250 kVp x-rays/ dose in Gy of test radiation (abbrev.)
As LET increases, RBE ____
Low-LET have __ RBE
High-LET have ___ RBE
Diagnostic x-rays have a RBE of __?
cells and tissues differ in biologic response
Why is RBE not practical for specifying radiation protection dose levels in humans?
Radiation Weighting Factor (Wr)
What is similar to RBE and used to calculate equivalent dose
Oxygen Enhancement Ratio (OER)
This describes the response of biologic tissue to radiation is greater when irradiated in an oxygenated state than when irradiated in an oxygen deprived state
Oxygen Enhancement Ratio (OER)
Dose required without O2/ Dose required with O2
OER is most pronounced in ___ radiation
The presence or absence of oxygen does not matter with what type of radiation?
free radical
a solitary atom or most often a combination of atoms that behaves as an extremely reactive single entity as a result of the unpaired electrons
Free radicals dramatically ___ the amount of biologic damage
The presence/absence of oxygen in tissue makes bioligic damage produced by free raddicals permaninet
organic peroxide compounds
The presence of O2 makes damage permanent by producing ____, which makes nonrestrable changes in the chemical composition
molecular, cellular, and organic
Bioligic damage from ionizing radiation can be observed on which 3 levels?
cell function
The structures of a cell's constituent molecules determines ___
chemical balance
Exposure to radiation can alter cell structures and disturbe the cell's ____ & ultimately the way it operates
somatic cells
Irradiation of ____ ___ may disrupt body processes
genetic cells
Irradiation of ____ ___ may be passed to future generations in the form of genetic mutations
DNA or water
When radiation interacts with a cell, ionizations or excitations occur in ___ or ____?
site of interaction
The action of radiation on the cell is classified based on the ___ __ _____.
Direct action
interaction with master molecules (DNA)
indirect action
interaction occurs in water molecules
Direct Action
This type of action ay occur after exposre to any type of radiation but is MUCH more likely with high LET radiation
chemical bonds
When ionizing particles interact directly with DNA, RNA, proteins and/or enzymes the reasult is breakage of ____ ____, which makes them abnormal both structurally and functionally.
Indirect Action
this typeo f action occurs when radiation interacts with water which produces free radicals
If free radicals interact with DNA the damage to the DNA is what type of action?
what type of action is more likely to occur?
ions and free radicals
Indirect action involves the breakdown of a water molecule in to smaller molecules, producing what?
HOH+ and e-
If an interaction with water occurs, what ion pair is formed from the water molecule?
How much damage is caused when HOH+ and e- recombine?
Positive and negative water molecules are ___, or they will break apart into smaller molecules.
unpaired electron
what makes free radicals highly reactive?
normal water molecule
if Hydrogen and hydroxyl ions recombine the form what? (no harm)
single-strand break, double-strand break, mutation, and covalent cross-links
What are the 4 effets of ionizing radiation on DNA?
Single-strand Break
Which effect on DNA occurs in low LET radiations and breaks into 2 sugar-phosphate chain that repair enzymes can reverse
point mutation
when a DNA breaks into 1 sugar-phosphate chain
Double-strand break
Which effect on DNA occurs when one ore more breaks in both sugar-phosphate chains occur and is more common with high LET.
The loss or change in a nitrogenous ase on a DNA chain; the alteration of the base sequences
genetic information
what is contained in the strict sequences of DNA bases?
1 or 2
If the cell divides, the mutation will be transfered to how many of the daughter cells?
Covalent Cross-Links
Chemical unions created beween atoms by the single sharing of one or more pair of electrons; can occur in many different forms and are potentially fatal to the cell.
when changes occur in the DNA molecule what exhibits the alteration?
radiation-induced chromosome breaks, chromosomal fragments, and chromosomal anomalies
What are the 3 effects of Ionizing radiation on chromosomes?
Radiation-induced chromosome breaks
What may be viewed microscopically (metaphase and anaphase) and can happen to the chromosomes of somatic and germ cells?
Metaphase and anaphase
During which phases of mitosis can you view radiation-induced chromosome breaks?
chromosomal fragments
What is produced by chromosome breakage and have a fractured extremity that have the ability to adhere to each other?
chromosome anomalies
What are chromosome or chromatid aberrations that can be observed in metaphase?
During which phase of mitosis can you view chromosome anomalies?
Chromosome aberrations
Chromosome anomalies that result when radiation occurs before DNA synthesis; each daughter cell exhibits this
Chromatid aberrations
Chromosome anomalies that result when radiation occurs after DNA synthesis; only 1 daughter cell exhibits the aberration
break rejoins with no visible damage (structural change)
part of the chromosome or chromatid is lost at the next cell division (structural change)
Broken-end rearrangement
grossly mis-shapen chromosome may be reproductive without visible damage to the chromosomes (structural change)
what does broken-end rearrangement result in?
target theory
Concept that DNA is the "master" molecule in a cell, andif it is inactivated by exposure to radiation, the cell will die.
Interactions occur only by ___
Instant death
x-ray or gamma ray doses of about 1000 Gy in a matter of seconds or minutes
Reproductive Death
cell does not die, but cannot reproduce; 1-10 Gy
"interphase death" cells die without attempting division; occurs spontaneously in both normal tissue and in tumors
The doser required to cause apoptosis is governed by the cell's
Mitotic death
"genetic death" occurs when a cell dies after one or more divisions
Mitotic Delay
can occur from doses as small as .01 Gy
chromosome breakage
a potential outcome when radiation interacts with a DNA macromolecule; can occur in one or both strands and results in a loss of genetic material
cell survival curve
A method of displaying the sensitivity of a particular type of cell to radiation
A cell survival curve for low LET radiation shows ___ change in survival at low doses
A cell survival curve for low LET radiaton shows a ____ in survival as dose increases (linear portion)
A curve for high LET does not have a shoulder, meaning it is ___.
Immature cells are undifferentiated and rapidly dividing, therefore they are ___ radiosensitive.
Mature cells are highly differentiated and divide slowly if at all, therefore they are ___ radiosensitive.
LET affects cell ____.
Oxygen ___ the effects of ionizing radiation by increasing tissue radiosensitivity
potential indirect damage
Oxygen increases the ___ ____ ____ of radiation.
Law of Bergonie and Tribondeau
Established that radiosensitivity is a function of the metabolic state of the cell receiving exposre
directly proportional
Radiosensitivity of cells is ___ ___ to their reproductive activity.
inversely proportional
Radiosensitivity of cells is ___ __ to thier degree of differentation.
least, greatest
The most pronounced radiation effects occur in cells with the ___ maturity and specialization and the ___ reproductive activity
hematologic depression
Effect of ionizing radiation on human cells that is a decrease in the number of blood cells in circulation
depletion of Immature blood cells
Effect of ionizing radiation on human cells that is a decrease in the number of cells produced in bone marrow
This happens after some cells in the bone marrow recover
among the most sensative cells of the Hematpoeitic system
30-60 days
Humans receiving 5Gys may die within ___ __ due to depletion of stem cells of the hematopoietic system
hematopoietic system
stem cells are part of which system?
LD 50/30
Dose that produces death in 50% of subjects in 30 days
LD 50/60
Dose that prodices death in 50% of subjects in 60 days
3-4 Gy
Lethal dose for humans
white blood cells
subgroup of leukocytes that defend the body against foreign antigens by producing antibodies
bone marrow
Lymphocytes manufactured in ___ are the most radiosensitive blood cells in the human body
.25 Gy
doeses of ____ depress the number of WBC
Type of WBC that plays an important role in fighting infection; dose of .5 Gy cand cause reduction
Scavenger type of WBC that fights bacteria and responds to irradiation by a sudden increase in number followed by a decrease
platelets that initiate blood clotting and prevent hemorrhage; .5 Gy depresses counts
epithelial tissue
Tissue found in the lining of intestines, mucous lining of respiratory tract, pulmonary alveoli, and lining of blood and lymphatic vessels that is very radiosensitive
muscle tissue
tissue that is highly specialized, does not divide, and is relatively insensitive to radiation
nervous tissue
tissue that is more radiosensitive in the embryo/fetus than in an adult
2 Gy
What is needed to cause temporary sterility of sperm and ova cells
5 or 6 Gy
What is needed to cause permanent sterility of sperm cells
5 Gy
What is needed to cause permanent sterility of ova cells?
highest energy level of photons in the x-ray beam; controls quality or penetration
Product of the eletron tube current and the amout of time that the tube is activated; determins quantity
If electromagnetic energy is transferred to the atoms it results in ____.
Absorbed Dose (D)
The amount of energy absorbed per unit mass; the more absorption the more possibility of biologic damage
gray (GY)
SI Unit for absorbed dose
traditional unit for absorbed dose
100 rad
1 Gy = ___ rad
primary radiation
Radiation produced by the tube through the bombarding of electrons into a positively charged target in a glass tube
glass window
X-trays leave the glass tube through the ___.
The glass window acts as a ___
___ is added to the collimator assembly to "harden" the beam
permanent inherent filtration
Combination of the x-ray tube glass wall and the added aluminum in the collimator
photos have varying energies and are therefore ___.
kilovolt (kV)
the energy of the electron inside the tube is expressed in terms of ___ applied across the tube
The average photon in the x-ray beam is about __ the energy of the highest energy photon.
Reduction in the number of primary photons in the x-ray beam through absorption and scatter as the beam passes through an object
direct transmission
primary photons pass through without interact; reach the IR
Indirect transmission
scattered phoons that reach the IR
The optimal x-ray image is formed when only ___ transmission x-rays reach the IR
air gaps and grids
2 things used to get rid of as much scatter from the IR as possible
primary photons
photons before they enter an object
exit photons
photons that emerge from the object and strike the IR
attenuated photons
photons that are scattered or absorbed
small-angle scatter
bending of the path of exit radiation and blurs the sharp outlines of dense objects
radiographic fog
small-angle scatter causes unwanted additional density called ___
What is the best method of reducing radographic fog?
Interaction with matter is ___
coherent scattering
"classical" scatter that results in no loss of energy; low energy photon transfers its energy by causing some or all of the electrons to vibrate
photoelectric absorption
When x-rays interact with an inner-shell electron and transfer enough energy to overcome the binding energry, this happens
compton scattering
When x-rays eject an outer-shell electron and is free to ionize, this is produced
pair production and photodisintegration
When an x-ray reacts with then nucleus, these can happen
coherent scattering, compton scattering, photoelectric absorption, pair production, and photdisintegration
What are the 5 processes of interaction?
Compton Scattering
"modified" scatter responsible for most of the scattered radiation produced during radiologic procedures
photoelectric absorption
the most important mode of interaction between x-ray photons and the atomsof the patients body for producing useful images
binding energy
energy that binds the electron in its orbit
photoelectric absorption
In this interaction, the x-ray photon surrenders all of its energy to the orbital electron and ceases to exist; the electron is ejected from its inner shell creating a vacancy
ejected electron with energy equal to the energy of the incident photon
photoelectric absorption
Which interaction is responsible for patient dose and the majority of biologic damage
characteristic photon
The vacancy created from the ejected electron is filled as outer shell electrons drop into the inenr shell by releasing energy in the form of a photon called a...
photoelectrons and characteristic x-ray photons
By-products of photoelectric absorption
Auger Electrons
alternative to the emission of characteristic photons; energy that would have appeared as a photon is used to eject an outer-shell electron; generates unbound electrons called...
energy of photons and atomic number of atoms
The probabiity of the occurrence of photoelectric absorption is determined by...
decreases, increases
Probabily of photoelectric absorption increases as incident photon energy ___ and atomic number ____
bone will absorb _ times as many photons as soft tissue
thickness and density
___ and ___ of a part increase the amount of photoelectric absorption
Photoelectric absorption has a great impact on this radiographic quality
Z number of Barium
Z number of iodine
contrast media
used when tissues/structures of similar atomic number must be distinguished
pair production
incoming photon strongly interacts with the nucleus of an atom; occurs at energy ranges far above diagnostic range (1.022 MeV)
positron and negatron
During Pair Production, energy of the photon is transformed into a ___ and a ___ each having the same mass
In Pair production; particle that eventually loses enough energy that it may be caputured by an atom
in pair production; partical that interacts with an electron and they annihilate eachother; matter to energy
positron emission tomography
Uses annihilation radiation
Occurs above 10MeV; rad therapy treatment; high energy photon collides with the nucleus of an atom, which absorbs all the photon's energy
interaction that createes an instability that is alleviated by emission of a neutron.
classical, elastic, or unmodified
What are the 3 other names for coherent scattering?
incoherent, inelastic, modified
What are the 3 other names for Compton scattering?
13.8, 7.4
What is the atomic number of bone? Soft tissue?
1.022 MeV
What must the energy of an incident photon be for pair production?
2 .511 MeV photons moving in opposite directions
What is the result of pair production?
any energy that is transmitted through matter
Ionizing radiation
a form with the energy to remove electrons from atoms and has the ability to cause harm t biologic tissues
electromagnetic and particulate
2 general categories of ionizing radiation
gamma rays and xrays
two types of ionizing rays
B. Non-interacting and small angle scattered photons.
Exit, or image-formation, radiation is composed of which of the following?
A. Primary photons and Compton-scattered photons
B. Non-interacting and small angle scattered photons.
C. Attenuated photons
D. Absorbed photons
C. Compton-scattered photons
Which of the following contributes significantly to the exposure of the radiographer?
A. Positrons
B. Electrons
C. Compton-scattered photons
D. Compton-scattered electrons
A. Absorption and scatter
Which of the following defines attenuation?
A. Absorption and scatter
B. Absorption only
C. Scatter only
D. Compton electrons
B. Compact bone
In the radiographic kilovoltage range, which of the following structures will undergo the most photoelectric absorption?
A. Air cavities
B. Compact bone
C. Fat
D. Soft tissue
A. Compton
In which of the following x-ray interactions with matter is the energy of the incident photon partially absorbed?
A. Compton
B. Photoelectric
C. Coherent
D. Pair production
Photoelectric interaction becomes significantly enhanced, leading to an increase in the absorbed dose in the body tissues or structures that contain the contrast medium
When a high atomic number solution is either ingested of injected into human tissue or a structure to visualize it during an imaging procedure, what occurs?
A. Energy of the incoming photon
Which of the following characteristics primarily differentiates the probability of occurrence of the various interactions of x-radiation with human tissue?
A. Energy of the incoming photon
B. Direction of incident photon
C. X-ray beam intensity
D. Exposure time
Which of the following influences attenuation?
Effective atomic number of the absorber
Mass density
Thickness of the absorber
A. 1 only
A decrease in contrast of the image by adding an additional, unwanted density (radiographic fog) results from which of the following interactions between x-radiation and matter?
1. Compton scattering
2. Pair production
3. Photoelectric absorption
A. 1 only
B. 2 only
C. 3 only
D. 1,2, and 3
C. Random in nature, and therefore the effects of such interactions cannot be predicted with certainty.
The interactions of x-ray photons with any atoms of biologic matter are:
A. Able to be preplanned to selective atoms in order to limit radiation exposure to those atoms
B. Important only in therapeutic radiology
C. Random in nature, and therefore the effects of such interactions cannot be predicted with certainty.
D. Unimportant in diagnostic radiology, making radiation protection unnecessary.
The transference of electromagnetic energy to the atoms of the material
Absorbed dose
The amount of energy absorbed per unit mass
C. The potential exists for irreparable damage because multiple-strand breaks in DNA are possible
For radiation protection, high-LET radiation is of greatest concern when a radionuclide has been implanted, ingested, injected, or inhaled because:
A. Only single-strand breaks in DNA are possible
B. The potential exists for repairable damage of single-strand breaks in DNA
C. The potential exists for irreparable damage because multiple-strand breaks in DNA are possible
D. The potential exists for repairable damage in DNA resulting from multiple-strand breaks.
B. Unpaired electrons
Free radicals behave as an extremely reactive single entity as a result of the presence of:
A. Paired electrons
B. Unpaired electrons
C. Paired neutrons and protons
D. Unpaired neutrons and protons
A. 1 only
Which of the following are classified as high-LET radiation?
1. Alpha particles
2. Gamma rays
3. x-rays
A. 1 only
B. 2 only
C. 3 only
D. 1,2, and 3
C. 4
A biologic reaction is produced by 3 Gy of a test radiation. It takes 12 Gy of 250-kVp x-radiation to produce the same biologic reaction. What is the relative biologic effectiveness of the test radiation?
A. 2.5
B. 3
C. 4
D. 8
B. Indirect action
Which action of ionizing radiation is most harmful to the human body?
A. Direct action
B. Indirect action
C. Epidemiologic action
D. Mitotic action
D. Water
Which molecules in the human body are most commonly directly acted on by ionizing radiation to produce molecular damage through an indirect action?
A. Protein
B. Carbohydrate
C. Fat
D. Water
B. When two direct hits occur in the same rung of the DNA macromolecule
When does ionizing radiation cause complete chromosome breakage?
A. When a single strand of the sugar-phosphate chain sustains a direct hit
B. When two direct hits occur in the same rung of the DNA macromolecule
C. When two direct hits occur in different rungs of the DNA macromolecule
D. When two direct hits are sustained at opposite ends of the DNA macromolecule
D. 1, 2, and 3
When significant numbers of lymphocytes are damaged by exposure from ioninzing radiation, the body:
1. Loses its natural ability to combat infection
2. Becomes more susceptible to bacteria
3. Becomes more susceptible to viral antigens
A. 1 and 2
B. 1 and 3
C. 2 and 3
D. 1, 2, and 3
C. Greatest reproductive activity, longest mitotic phases, and least maturity
With respect to the law of Bergonie and Tribondeau, which of the following would best complete this statement? "The most pronounced radiation effects occur in cells having the_______."
A. Least reproductive activity, shortest mitotic phases, and most maturity
B. Greatest reproductive activity, shortest mitotic phases, and most maturity
C. Greatest reproductive activity, longest mitotic phases, and least maturity
D. Least reproductive activity, shortest mitotic phases, and least maturity
D. All cells are radiosensitive
What do basal cells of the skin, intestinal crypt cells, and reproductive cells have in common?
A. All cells are hypoxic
B. All cells are premalignant
C. All cells are radioinsensitive
D. All cells are radiosensitive