Name____________________________________
INTRODUCTORY RADIATION BIOLOGY
Exam I
2014
WHEREVER POSSIBLE, SHOW ALL WORK!!! AND UNITS!!!
NO WORK, NO CREDIT!!!
1.
The broadcast frequency of a college radio station is 183 MHz, or 1.83 × 108 s-1. What
are the wavelength and energy of the radio waves?
2.
Rank the following radiations in order of increasing LET (i.e., beginning with the lowest
LET radiation = 1 and the highest LET radiation = 6).
a.
b.
c.
d.
e.
f.
3.
5 MeV proton
140 keV gamma photon
10 MeV electron
5 MeV alpha particle
500 keV positron
500 keV alpha particle
_____
_____
_____
_____
_____
_____
Cobalt-60 (6027Co) has a half-life of 5 years. It decays by β- emission (β- = 318 keV) to
an excited state of nickel (Ni) that lies 2.5 MeV above the ground state. This state deexcites instantaneously (<1 ns) to an excited state that lies 1.33 MeV above the ground
state. In turn, this second state de-excites instantaneously (<1 ns) to the ground state.
a. Sketch a decay scheme that is consistent with this information.
1
Name____________________________________
b. The Z of the Ni daughter is _____, and the A is _____.
c. True or False (circle one): The excited states of Ni are “metastable.”
d. Among other applications, 60Co sources are still in use for external beam radiotherapy
of cancer, bone marrow ablation, and food sterilization. The irradiator in our Nuclear
Engineering Department was delivered in 1975 and contained 1011 Ci of 60Co at that
time. When MU researchers started using a new 137Cs irradiator in 2000, how much
radioactivity remained in the old 60Co source?
e. List all the emissions (i.e., photons and particles) that occur during the decay of 60Co.
4.
In lead, the linear attenuation coefficient for a 1.33 MeV photon is 0.63 cm-1.
a. What is the half-value layer for absorption of this photon in lead?
b. What is the mean free path of this photon in lead?
2
Name____________________________________
c. How many cm of lead are required to reduce the initial intensity of a narrow beam of
the photons by 95%?
d. Approximately how many half-value layers is the thickness of lead required to reduce
the photon intensity to 5% of the original?
5.
The range of a 6.8 MeV alpha particle (i.e., 42He+2) in soft tissue is 34.9 µm.
a.
What is the LET of this alpha particle in soft tissue?
b.
Estimate the LET of a 6.8 MeV deuteron (i.e, 21H+1) in soft tissue.
3
Name____________________________________
6.
TRUE/FALSE
_____ a.
A 15 MeV electron is normally considered a type of high LET radiation.
_____ b.
Becquerel and the Curies won the 1903 Nobel Prize in Physics for discovering
and characterizing the phenomenon of “radioactivity.”
_____ c.
As the energy of a charged particle increases, the LET of the particle decreases.
_____ d.
The range of 200 keV gamma rays in water is less than the range of 1 MeV
electrons in water.
_____ e.
There is no detectable difference between a 72 keV x-ray and a 72 keV gamma
ray.
_____ f.
In general, alpha particles are considered a type of high LET radiation.
_____ g.
Positrons have exactly the same mass as electrons.
_____ h.
Radionuclides that are neutron rich generally decay by positron emission and/or
electron capture.
7.
The amount of energy contained in a dose of ionizing radiation that could be
lethal to a human being is equivalent to
a.
b.
c.
d.
8.
the energy required to power a nuclear submarine.
the energy it took for all the slaves to build the Great Pyramids of Giza.
the amount of heat absorbed by drinking one sip of hot coffee.
enough energy to cause spontaneous human combustion.
In Compton scattering, the energy of the scattered photon is
a.
b.
c.
d.
e.
always less than the energy of the incoming photon.
always equal to the energy of the incoming photon.
equal to the energy of the incoming photon minus the binding energy of
the Compton electron.
all of the above.
none of the above.
4
Name____________________________________
9.
The range of a positron in matter is short. At the end of its path, the positron
encounters an electron in a nearby atom and undergoes an ___________________
reaction. By conservation of energy, the masses of the two particles are converted
into two photons, each with an energy of ______________, and by conservation
of momentum, these photons are emitted at an angle of approximately _________
degrees.
10.
Briefly define or describe (no more than 1-2 sentences):
a.
The atomic mode of energy loss that competes with x-ray emission.
b.
LET
c.
Wilhelm Conrad Röntgen
d.
Ionizing radiation
e.
The main process by which a 1 MeV photon will lose energy when passing through an
absorber, such as soft tissue.
f.
Mean free path
g.
Half-life of a radionuclide
5
Radiation Biology Exam 2 2014
Name:___________________________
SHOW ALL WORK ON THE EXAM TO RECEIVE FULL CREDIT
1. True-False
___
a. Radiation exposure is more likely to result in cell transformation and cancer than cell
death.
___
b. The oxygen enhancement ratio is linear such that cells at 30 mmHg oxygen are
roughly half as sensitive to radiation-induced death as cells as 60 mmHg oxygen.
___
c. Patients with Ataxia Telangiectasia are born with at least one deficiency in nucleotide
excision repair.
___
d. On average, low LET radiation causes ionizations in tissue that are more closely
spaced than high LET radiation.
___
e. In low LET radiation, the D0 and the D37 are identical.
2.
Briefly define and/or explain
a. Potentially lethal radiation damage
b. The significance of the value of n, the extrapolation number.
3.
In examining the survival curves that result from irradiating a human cell line with three
different kinds/conditions of ionizing radiation, you would conclude that the following
statements are TRUE or FALSE.
___a. Curve C was likely to be produced by irradiating the cells with x-rays under more oxygen
than Curve B.
___b. The D37 for Curve A and B are approximately the same.
___c. Curve B represents cells that were irradiated with more sulfhydryl containing thiol
molecules present than Curve C, assuming both cells in B and C were irradiated under the
same oxygen concentration with the same type of low-LET radiation.
___d. If the only variable altered in the experiment generating Curves B and C is dose rate,
Curve B likely received the higher dose rate.
___e. Curve A is representative of killing cells primarily by a one-hit process.
4.
For the phases of the cell cycle listed below, select the correct phases in which
Homologous Recombination Repair can occur.
G1
S
G2
M
a.
b.
c.
d.
6.
All phases of the cycle
Only G1 and S
Only S and G2
Primarily M and S
Order the steps involved in the non-Homologous End Joining process as described in
lecture and, at appropriate steps, identify the enzyme involved.
Step
Enzyme
1. Damage recognition
a) DNA polymerase
2. Enzyme recruitment and end processing b) DNA-dependent protein kinase catalytic
subunits (DNA-PKcs)
3. Gap in backbone is sealed
c) Ligase
4. Bases are replaced
d) Ku proteins
First step _______ Enzyme________
Second step _______ Enzyme________
Third step _______ Enzyme________
Fourth step _______ Enzyme________
7.
In the curves above, if all curves represent cells exposed to radiation of the same quality
at the same oxygen level, which curve represents cells incubated under the LOWEST
dose rate while being irradiated?
a.
b.
c.
d.
8.
Curve A
Curve B
Curve C
Dose rate does not affect this type of radiation
Draw two cell survival curves. Make Curve A represent cells irradiated with alpha
particles. Make Curve B represent cells irradiated with an electron beam. Draw them
such that D0 is approximately the same for both curves. Label each curve.
9.
For the two cell survival curves above, one 250 keV x-rays, and one 10 MeV neutrons,
calculate the relative biological effectiveness of the neutrons to reduce the surviving
fraction of cells to 50% of the initial number.
10.
At the end of the quarter, you receive your radiology badge report stating that you have
received 20 mREM radiation absorbed dose in the previous reporting period.
a.
If your exposure has been exclusively to gamma radiation, calculate the number
of Rad of radiation received from these gamma rays.
b.
Convert this absorbed dose to mSv.
11.
A researcher using open source radioactivity inadvertently spills a container with a
solution of antibody labeled with Astatine-211, an alpha emitting isotope on her hand.
Fortunately, she is wearing appropriate protective gloves and a ring dosimeter. She has
previously been working with beta-emitting isotopes earlier in the month. At the end of
the month, her ring badge has recorded 4 REM. Alpha particles have a QF of 20.
a. If 0.1 cGy of the exposure was the alpha particles, how much exposure resulted from
the beta particles in cGy?
b. If the alpha particles are 1 MeV and the beta particles are 500 MeV, which is more
highly penetrating? Why?
12.
In the cell survival curve above, please identify the regions in which the following occur:
1.
Linear portion of the survival curve
2.
Quadratic portion of the survival curve
3.
Repair shoulder
13. On the above log-linear graph paper, draw two cell survival curves. Curve A has an
extrapolation number of 1 and a D0 of 1.4 Gy. Curve B has a D37 of 2.3 Gy and a D50 of
1.8 Gy. Calculate the following:
a. D0 of the low-LET curve
b. n of the low-LET curve
14. In the survival curve above, draw a second curve that demonstrates how the original curve
would be shifted if oxygen was reduced from arterial levels (100 mmHg) to nearly zero.
Name:__________________________
Exam III, Introduction to Radiation Biology
November 13, 2014
Dr. Lattimer
Please indicate the one best answer for each of the following questions. (1-66)
1. Outside of the Chromosomes in the nucleus where else in the cell is DNA found?
a. Golgi bodies
b. Nuclear membrane
c. Cell membrane
d. Mitochondria
e. DNA is found only in the Nucleus
2. Which of the following is NOT one of the nucleic acids making up the base pairs of the
DNA?
a. Guanine
b. Cytosine
c. Adenine
d. Thymine
e. Ribosine
3. Approximately how many genes are estimated to be present in the human genome?
a. 6,000
b. 60,000
c. 600,000
d. 6,000,000
e. 60,000,000
4. Absence of which of the following compounds would be most likely to reduce the
effects of ionizing radiation on the DNA?
a. Water
b. Carbon Dioxide
c. Dextrose
d. Phosphate
e. Molecular Nitrogen
5. Approximately what fraction of DNA injury from ionizing radiation is due to direct
interaction of the radiation with the DNA molecule?
a. One fourth
b. One third
c. One half
d. Two thirds
e. Three quarters
Name:__________________________
6. Which of the following is the most potent promoter of radiation injury to the DNA?
a. Molecular Nitrogen
b. Carbon Dioxide
c. Molecular Hydrogen
d. Molecular Oxygen
e. Helium
7. Which of the following types of DNA injury is most likely to result in severe dysfunction
of the DNA?
a. Ribose molecule deletion
b. Guanine molecule deletion
c. Nucleotide base pair deletion
d. Single strand break
e. Double strand break.
8. Which of the following would be most likely to result in a mutation of DNA function?
a. Ribose molecule deletion
b. Guanine molecule deletion
c. Nucleotide base pair deletion
d. Single strand break
e. Double strand break.
9. Which of the following would NOT be likely to improve repair of potentially lethal
radiation injury to the DNA?
a. Hypoxia
b. Hyperthermia
c. Hypothermia
d. Low intranuclear pH
e. Free radical scavenging drugs
10. Which of the following is most likely to result in an accurate repair of an ionizing
radiation induce double strand break?
a. Nucleotide excision repair
b. Base excision repair
c. Non-Homologous End joining
d. Homologous Recombination repair
e. Chromatid Homozygosity
Name:__________________________
11. Which of the following represents the predominate type of radiation injury resulting in
death of the cell at high radiation doses (> 3x Do)
a. Double strand breaks
b. Multiple single strand breaks
c. Multiple Base pair deletions
d. Accumulated multihit injury
e. Multiple Chromosome exchanges
12. Which of the following represents the time period generally accepted as the time
required for DNA repair to be completed following a radiation injury.
a. 1 hour
b. 3 hours
c. 6 hours
d. 9 hours
e. 12 hours
13. For a given dose of 360 cGy, which of the following is a true statement?
a. Receipt of this dose over a 24 hour period will reduce the acute effects of the
dose
b. This radiation dose would be expected to kill 100% of humans
c. The principal effect of this acute dose in a human would be mutations in
offspring
d. This dose is below the threshold for non-repairable radiation injury
e. DNA repair from this radiation dose would only require a couple hours to
complete
14. Which of the following phases of the cell cycle is generally accepted to be most resistant
to radiation injury by high LET radiation.
a. G1
b. G2
c. M
d. Go
e. S
15. Which of the following phases of the cell cycle only lasts about 5-8 hours and is
therefore quite sensitive to radiation injury?
a. G1
b. G2
c. G0
d. S
e. M
Name:__________________________
16. Severe chromosomal injury caused by ionizing radiation is most likely to be manifest
following which of the following phases of the cell cycle?
a. G1
b. G2
c. G0
d. S
e. M
17. Reassortment is the phenomenon that occurs following a radiation event where cells
that are killed by the radiation are replaced by recruiting cells from which of the
following phases of the cell cycle to replace those that were killed?
a. G1
b. G2
c. G0
d. S
e. M
18. Which of the following statement is true?
a. The capacity to repair radiation injury to the DNA is greatest in rapidly dividing
cells
b. The DNA of cells with long cell cycle times is inherently less sensitive to radiation
c. Cells in the G2 phase of the cell cycle have enhanced DNA repair capabilities
d. Tissues with rapidly dividing cells with manifest radiation injury more quickly
e. Tissues with rapidly dividing cells are less likely to exhibit mutations after
irradiation
19. Bone marrow would generally be thought to be comprised of which of the follow cell
types?
a. Vegetative intermitotic cells
b. Differentiating intermitotic cells
c. Multipotential Connective tissue cells
d. Reverting post mitotic cells
e. Fixed Post Mitotic cells.
20. Which of the following would be most likely to require a very high dose of radiation to
exhibit and acute response to irradiation?
a. Vegetative intermitotic cells
b. Differentiating intermitotic cells
c. Multipotential Connective tissue cells
d. Reverting post mitotic cells
e. Fixed Post Mitotic cells.
Name:__________________________
21. Which of the following would NOT generally be considered to be a Reverting Post
Mitotic Cell type?
a. Liver cells
b. Skeletal muscle cells
c. Endothelial cells
d. Tubular epithelial cells of the kidney
e. Cells lining the alveoli of the lungs (pneumocytes)
22. According the Michealowski classification system which of the following would not be
an H-type cell?
a. Spermatagonia
b. Intestinal crypt cells
c. Bone marrow cells
d. Basal cells of the skin
e. Fibroblasts
23. “Critical Cells” within a tissue may be defined as which of the following
a. The cell type within a tissue that has the highest total radiation sensitivity and is
required for the tissue to survive.
b. The cell type within a tissue that provides the critical function of that tissue.
c. The cell type within a tissue that is most likely to be depleted by radiation injury
d. The cell type within a tissue that has the greatest numerical redundancy
e. The cell type within a tissue that is least likely to repopulate following moderate
radiation injury
24. Which of the following types of radiation would be expected to cause the greatest
damage to bone marrow per unit of radiation dose (gray)?
a. Protons
b. Gamma rays
c. X-rays
d. Beta particles
e. Alpha particles
25. Which of the following cell types would be most likely to exist in a hypoxic state?
a. Bone marrow cells
b. Cells in the intestinal epithelium
c. Cells in the spinal cord
d. Sperm cells
e. None of the cells above
Name:__________________________
26. Clonogenic assays measure which of the following capacities of a cell population or
tissue following irradiation?
a. Ability to perform the normal functions of the cell
b. The ability of the cells to repopulate themselves
c. The ability of the cells to repair radiation injury to the DNA
d. The ability of the cells to mature following radiation injury
e. The ability of the cells to survive a radiation injury
27. Based on the multitude of assays for dividing cells which of the following radiation
doses is most closely representative of Do?
a. 1.0 Gray
b. 1.5 Gray
c. 2.0 Gray
d. 2.5 Gray
e. 3.0 Gray
28. Which of the following would be the assay that would be expected to provide the most
accurate data on the continued viability of a tissue following irradiation.
a. In vitro Clonogenic assay
b. In vitro Functional assay
c. In vivo Clonogentic assay
d. In vivo Functional assay
e. In vitro Transplantations assay.
29. Which of the following would be most useful in assessing the clinical effects of an
ingested dose of a radionuclide such as 131Iodine.
a. In vitro Clonogenic assay
b. In vitro Functional assay
c. In vivo Clonogentic assay
d. In vivo Functional assay
e. In vitro Transplantations assay
30. If a radiation dose is described as having an LD 60/60, which of the following is the best
description of what this means?
a. 60 percent of the subjects will die after 60 Gy of radiation
b. 60 Gray of radiation will kill the subjects in 60 days
c. 60 Gray will kill 60 percent of the subjects in 60 days
d. 60 percent of the subjects will be dead after 60 days
e. 60 percent of the subjects will survive for 60 days
Name:__________________________
31. Which of the following is NOT an acute injury response you could see in an early
responding tissue.
a. Erythema
b. Edema
c. Dry desquamation
d. Hemmorhage
e. Fibrosis
32. With regards to radiation biology, regeneration of a tissue following a radiation injury is
also known as which of the following?
a. Reassortment
b. Recruitment
c. Repair
d. Repopulation
e. Reoxygenation
33. Following death of skeletal muscle cells in the area of radiation therapy on the back
those cells may be replaced. Which of the following cell types is most likely to do the
replacement?
a. Skeletal muscle cells
b. Fat cells
c. Primitive smooth muscle cells
d. Fibroblasts
e. No replacement will occur
34. Which of the following cell types is most likely to exhibit acute early radiation response
following a large dose of x-rays to the skin?
a. Endothelial cells
b. Basal cells of the skin
c. Red blood cells
d. Cells on the surface of the skin
e. Subcutaneous fat cells
35. For any given radiation dose, what is the effect of the volume of tissue irradiated on the
severity of the acute changes in that tissue volume?
a. Increasing the volume of tissue irradiated increases the severity of the effects
b. Decreasing the volume of the tissue irradiated increases the severity of the
effects
c. The volume of tissue irradiated has no effect on the severity of the effects
d. Decreasing the volume of tissue irradiated reduces the total dose received.
e. Increasing the volume of tissue irradiated decreases the severity of the effects.
Name:__________________________
36. Which of the following types of cells from the Hemopoietic system is most sensitive to
ionizing radiation killing?
a. Plasma cells
b. Macrophages
c. Red blood cells
d. Lymphocytes
e. Platelets
37. Which of the following portions of the digestive system is most resistant to radiation
injury?
a. The esophagus
b. The stomach
c. The small intestine
d. The colon
e. The rectum
38. Which of the following cell types found in the male reproductive tract is most resistant
to radiation injury with regards to its function?
a. The germinal epithelium of the spermatigonia
b. The sperm
c. The cells lining the ducts of the testes
d. The cells which produce testosterone
e. The endothelium of the blood vessels.
39. Sensitivity of the musculoskeletal system to radiation injury is to some degree age
dependent. At which of the following ages would you expect this sensitivity to
plateau (stop decreasing) in most individuals?
a. 5 years of age
b. 10 years of age
c. 15 years of age
d. 20 years of age
e. 25 years of age
40. Development of the central nervous system continues virtually from the time of
implantation until well after birth in humans. Which of the follow would be a likely
consequence of radiation therapy to the central nervous system of a seven year old?
a. Stunting of growth and small stature as an adult
b. Ocular issues leading to blindness as an adult
c. Partial to complete deafness as an adult
d. Incoordination and difficulty in walking when an adult
e. Decreased cognitive capability as an adult
Name:__________________________
41. During the prodromal phase of a whole body radiation syndrome the most common
clinical manifestation of the syndrome is which of the following?
a. No clinical signs
b. Nausea
c. Seizures
d. Hyperesthesia
e. Hair loss
42. For a patient with bone marrow syndrome following whole body irradiation, which of
the following is the most likely life threating problem?
a. Dehydration
b. Hemorrhage
c. Severe Anemia
d. Immune system suppression
e. Systemic infections
43. At which of the follow times of gestation is a radiation dose of .5 gray to a human fetus
likely to result in fetal death due to destruction of most or all of an organ system?
a. 10-15 days after conception
b. 16–45 days after conception
c. 46-90 days after conception
d. 90-150 days after conception
e. after 150 days after conception
44. Because of the sensitivity of a fetus to radiation injury there are special rules for
pregnant radiation workers. Which of the following represents the current maximum
radiation dose a pregnant radiation worker is allowed to have to her abdomen during
a pregnancy?
a. 200 mRem
b. 500 mRem
c. 1000 mRem
d. 3000 mRem
e 5000 mRem
45. Which of the following represents the most likely acute sequelae to a whole body
radiation dose of 0.75 Gray.
a. Decrease in disease resistance
b. Systemic infections
c. Induction of cancer
d. Anemia
e. Diarrhea
Name:__________________________
46, Which of the following phases of development of an immune response to a new
disease is high sensitive to a whole body radiation dose.
a. Preinduction phase
b. Induction phase
c. Production
d. Preinduction and Production
e. Induction and Production
47. Which of the following statements about carcinogenesis due to radiation exposure is
true.
a. Cancer is rarely caused or promoted by radiation exposure
b. The most common cancers associated with radiation exposure are brain tumors
c. Radiation therapy doses are so high that cancer induction is rare.
d. Increased radiation dose increases the risk of cancer induction.
e. Solar radiation from the sun is not a risk because it does not cause ionization.
48. Which of the following represents positive factor gene?
a. Protooncogene
b. DNA repair gene
c. Tumor suppressor gene
d. P53 gene
e. P39 gene
49. A cell which is potentially cancerous must retain which of the following characteristics
in order to grow into a cancer.
a. It must have a mutation of, or inactivation of the P53 gene
b. It must have inactivation of all tumor suppressor genes
c. It must have an amplification of a protooncogene
d. It must have a mutation or inactivation of DNA repair genes
e. It must retain clonogenic capacity
50. P53 is one of the principal genes which mediates apoptosis. Where in the cell cycle
does apoptosis under the influence of P53 occur.
a. Mitosis
b. Early G1
c. G0
d. G1-S junction
e. Late S phase
Name:__________________________
51. Hypoxia increases the tumor cells resistance to radiation injury but the hypoxia must be
profound. Which of the following tissue oxygen tensions is a level at which this effect
would result in a level at which cells are approximately 2.5 times more sensitive than
extremely hypoxic cells?
a. 100 mmHg
b. 50 mmHg
c. 10 mmHg
d. 5 mm Hg
e. 2 mm Hg
52. Tumor hypoxia is associated with which of the following attributes of cancerous
growths?
a. Chaotic organization blood vessels in the tumor
b. Poorly developed capillary bed in the tumor
c. Vasospasms of small arterial vessels in the tumor
d. Uncontrolled cellular reproduction within the tumor
e. All of the above
53. Which of the following tumor growth fractions would be considered to be unusual?
a. 0.1%
b. 0. 5%
c. 1%
d. 2%
e. 10%
54. Tumors typically will lose more cells from their populations than normal tissues. Which
of the following ways in which cells are lost from the tumor represents a high degree of
malignancy?
a. Non-viable replication
b. Hypoxic cell death
c. Destruction by immune cells
d. Apoptosis
e. Shedding into the vasculature
55. The process whereby tumors are able to survive a course of radiation therapy would
most likely be due to which of the following?
a. Reoxygenation
b. Repopulation
c. Reassortment
d. Repair of radiation injury
e. Recruitment
Name:__________________________
56. Which of the following is not an advantage which normal tissues have over rapidly
growth cancer tissues?
a. Reoxygenation
b. Repopulation
c. Reassortment
d. Repair of radiation injury
e. Recruitment
57. Which of the following represents the major advantage which late responding normal
tissues have over cancer tissues?
a. Reoxygenation
b. Repopulation
c. Reassortment
d. Repair of radiation injury
e. Recruitment
58. Overall the maximum advantage of normal tissues over cancer tissues with regards to
tissue and cell survival occurs in the range of Do. Which of the radiation dose
equivalents below would fall in the general range of Do for mammalian cells/
a. 1,0 Rem
b. 1.5 Rem
c. 2.0 Rem
d. 2.5 Rem
e. 3.0 Rem
59. In most cases radiation injury leads to loss of cells from a tumor cell population
principally by which of the following mechanisms.
a. Failed Mitosis
b. Apoptosis
c. Cell senescence
d. Mitotic delay
e. Interphase death
60. Which of the following types tissues would be most severely affected by the use of 5
5gray fractions to deliver 25 gray rather than 15 1.66 gray fractions?
a. Bone marrow
b. Fibrosarcoma cancer
c. Intestinal mucosa
d. The skin
e. Spinal cord
Name:__________________________
61. Which of the following may provide some rationale for limited fractionation of high
LET particle radiation treatments?
a. Reoxygenation
b. Repair
c. Reassortment
d. Repopulation
e. Recruitment
62. Which of the following adjuncts to or alternate types of radiation therapy is NOT
commonly used in clinical practice?
a. Radioprotective agents
b. Halogenated Pyrimadines
c. High LET radiation
d. Radioactive isotope implantation
e. External beam modulation
63. Which of the following is a mechanism by which a hypoxic cell sensitizer can work at
least in theory?
a. Directly acts as an oxygen mimic to fix DNA damage
b. Creates free radicals in the absence of oxygen or radiation
c. Inserts large halogen atoms in to DNA to increase DNA fragility
d. Increases the distance that oxygen can migrate through tissue
e. Cause all blood vessels feeding a tumor to maximally dialate
64. Which of the following high LET particles would have the narrowest Bragg-Gray peak,
the sharpest drop-off after the peak and hence require the most energy modulation to
treat a tumor?
a. Neutrons
b. Protons
c. Helium Nuclei
d. Neon Nuclei
e. Alpha Particles
65. Hyperthermia is considered to be synergistic to ionizing radiation in causing cell death
of all cell types but which of the following would be an effect relevant to both normal
and hypoxic cells?
a. Hyperthermia is a potent inhibitor of DNA repair
b. Hyperthermia is effective in areas of poor blood flow.
c. Hyperthermia increases metabolic demand in nutritionally deprived cells
d. Hyperthermia is most effective against cells in S-phase
e. Hyperthermia particularly stresses cells in a low pH environment
Name:__________________________
66. In brachytherapy where a radioactive source is implanted into a tumor to deliver a
radiation dose at about 50 Gray per hour which of the following would be a reason
why brachytherapy can be so effective?
a. There is no fractionation of the radiation exposure
b. The radiation is being delivered by a high LET particle
c. The radiation exposure time is shorter
d. The radiation hits all cycling cells in mitosis
e. Continuous irradiation accelerates repair
67. Short answer question: 10 points
Present a short explanation of each of the 4 R’s of radiation biology and relate how they would be
expected to come into play or influence the response of bone marrow to a 4 Gray radiation event.
Name:__________________________
Answer Sheet.
Name:
________________________
1 ___________
23 ___________
45 ___________
2 ___________
24 ___________
46 ___________
3 ___________
25 ___________
47 ___________
4 ___________
26 ___________
48 ___________
5 ___________
27 ___________
49 ___________
6 ___________
28 ___________
50 ___________
7 ___________
29 ___________
51 ___________
8 ___________
30 ___________
52 ___________
9 ___________
31 ___________
53 ___________
10 ___________
32 ___________
54 ___________
11 ___________
33 ___________
55 ___________
12 ___________
34 ___________
56 ___________
13 ___________
35 ___________
57 ___________
14 ___________
36 ___________
58 ___________
15 ___________
37 ___________
59
16 ___________
38 ___________
60 ___________
17 ___________
39 ___________
61 ___________
18 ___________
40 ___________
62 ___________
19 ___________
41 ___________
63 ___________
20 ___________
42 ___________
64 ___________
21 ___________
43 ___________
65 ___________
22 ___________
44 ___________
66 ___________
__________
Name:__________________________