Introductory Radiation Biology
WHEREVER POSSIBLE, SHOW ALL WORK!!! AND UNITS!!!
NO WORK, NO CREDIT!!!
1. On his way to work, Dr. Lewis listens to KCMQ, broadcasting at a frequency of 96.7 MHz (9.67 ×
107 s-1). What is the wavelength and energy (in eV) of these radio photons?
2. 62Sm (T1/2 = 46 h) is used for treatment of skeletal metastases in prostate and breast cancer
patients, as well as for treatment of bone cancer in children and dogs. Drs. Stephanie Essman
and Mike Lewis in the MU Department of Veterinary Medicine and Surgery studied the
biological damage to growing bones caused by 153Sm, in order to learn how to make this
treatment safer and more effective for children. 15362Sm decays exclusively to 15363Eu (stable),
with a decay energy of 810 keV. In 72% of events, 15362Sm decays to the ground state of 15363Eu.
In 28% of events, 15362Sm decays to an excited state that lies 103 keV above the ground state of
63Eu and de-excites to the ground state in less than 1 ns.
a. Sketch a decay scheme that is consistent with this information.
1. is proton rich.
2. is neutron rich.
3. decays by isomeric transition.
4. can be used for nuclear power.
c. Given the conversion of matter to energy, which nuclide is lighter (i.e., has lower mass)?
d. At the University of Missouri Veterinary Medical Teaching Hospital (VMTH), Dr. Jim
Lattimer treats dogs with bone cancer using the radiopharmaceutical 153Sm-EDTMP,
produced by the University of Missouri Research Reactor (MURR). At MURR, a dose of
100 mCi of 153Sm-EDTMP is prepared for shipment to the VMTH at 1:00 pm on Monday,
and Dr. Lattimer needs 20 mCi to treat a dog scheduled for a 9:00 am appointment on
Friday. How much 153Sm will Dr. Lattimer have when his patient arrives? Will he have
enough to give the prescribed dose?
3. The linear attenuation coefficient (μ) of the 103 keV 153Sm photon is 0.15 cm-1 in bone.
a. What is the half-value layer (HVL) of this photon in bone?
b. How many cm of bone are required to reduce the initial intensity (I0) of these photons
by 90% (i.e., I = 10% of I0)?
c. Approximately how many half-value layers (HVLs) is this?
4. The range of a 6.8 MeV alpha particle in soft tissue is 34.9 µm.
a. What is the LET (in keV/μm) of this alpha particle in tissue?
b. Estimate the LET (in keV/μm) of a 6.8 MeV proton (i.e., 11H+1) in tissue.
_____ a. The range of a 62 keV tungsten characteristic x-ray is longer than the range of a
5 MeV alpha particle in soft tissue.
_____ b. In is produced by proton irradiation of 111Cd using a cyclotron. Therefore, it is
generally used for diagnostic imaging.
_____ c. Bremsstrahlung radiation emitted from an x-ray tube is always monoenergetic.
_____ d. Pierre and Marie Curie shared the 1903 Nobel Prize in Physics with Henri
Becquerel for the discovery of natural radioactivity.
_____ e. As the energy of a given type of charged particle increases, its range in matter
_____ f. Alpha particles emitted during radioactive decay are always observed at discrete
energies, while beta particles (β- and β+) resulting from radioactive decay are
always observed as a continuous energy spectrum.
_____ g. When a high-energy charged particle (e.g., a 15 MeV LINAC electron) first
collides with an atom in an absorbing medium, it usually transfers only a tiny
fraction of its kinetic energy to that atom.
_____ h. Without knowing the mechanism of emission, it is impossible to distinguish
Auger and conversion electrons using a conventional radiation detector.
6. Rank the following forms of ionizing radiation in order of increasing LET. (Fill in the blanks: rank
the lowest LET radiation number 1 and the highest number 6.)
a. 140 keV gamma ray _____
b. 5 MeV electron _____
c. 5 MeV proton _____
d. 500 keV positron _____
e. 500 keV alpha particle _____
f. 5 MeV alpha particle _____
7. In terms of radiation biology effects, the most important mechanism by which photons interact
with soft tissue is
a. Compton scattering.
b. the photoelectric effect.
c. transfer of an average of 60 eV by collision with an atom.
d. pair production.
e. none of the above.
8. If you were to absorb 67 calories of energy (equal to 1.75 × 1021 eV), which process is most likely
to ruin your whole day?
a. Being lifted overhead by a circus strongman.
b. Drinking one sip of hot coffee.
c. Absorbing a lethal dose of ionizing radiation.
d. Having your body temperature increase to 37.002 °C.
9. The range of charged particles in matter is, by definition, always
a. approximately 4 cm.
b. impossible to estimate.
e. none of the above.
10. Anytime a nucleus is capable of emitting a gamma ray,
a. it must be undergoing isomeric transition.
b. it must have been left in an excited state following alpha or beta minus decay.
c. an orbital electron could be ejected as an internal conversion electron instead.
d. all of the above.
e. none of the above.
11. Briefly define, identify, or describe.
a. Ionizing radiation
b. Radioactivity, or radioactive decay
d. Wilhelm Conrad Röntgen
e. Photoelectric effect
f. The major decay modes of proton rich radionuclides
g. Half-life of a radionuclide
Radiopharmaceuticals in Nuclear Medicine
Fall 2010, Exam 2
1. Identify which of the following SPECT and PET radiopharmaceuticals are currently used for
assessment of myocardial (heart muscle blood flow) [more than one answer is possible].
a) N-ammonia e) Rb+
b) Tc-ECD f) Thallous chloride
c) Tc-HMPAO g) Tc-DISIDA
d) Tc-sestamibi h) Tc-tetrofosmin
2. Tc-S-colloid is used for gastric emptying and lymph node imaging studies in patients.
a) What is a colloid?
b) Tc-S-colloid is considered
i. very stable
ii. moderately stable
iii. not very stable
c) The size of 99mTc-S-colloid is considerably smaller in diameter than 99mTc-MAA particles
(True or False).
3. The physical properties of 18F are:
a) half-life _______
b) mode of decay__________________
c) energy of photons emitted resulting from the decay of 18F.
4. a) Explain (a sketch may help) how the glomerular filtration (GF) process occurs in the kidneys
for clearance of some radiopharmaceuticals.
b) Radiopharmaceuticals that are cleared from the blood primarily via the GF route are:
i) small and hydrophilic
ii) small and hydrophobic
iii) large (> 10 K Daltons) and hydrophobic
iv) large (> 10 K Daltons) and hydrophilic
5. The mechanism of uptake of some radiopharmaceuticals occurs by passive diffusion of the
radiopharmaceutical from the blood into the tissue/cells/organ. Describe what “Passive
Diffusion” is and provide two examples of radiopharmaceuticals that localize by the process.
6. Define or describe the following terms.
a) Blood Brain Barrier
c) First pass “Extraction Efficiency” of a radiopharmaceutical from the blood by a tissue.
d) Blood plasma
7. F-fluoride is used for imaging _____________________________________
8. What is the mechanism of trapping of 99mTc-sestamibi in the cells where it localizes?
9. a) The overall charge on 99mTc-mebrofenin is
b) The cell in the liver involved in clearance of 99mTc-mebrofenin from the blood is
___a. TcO is primarily cleared from the body by the tubular secretion process in the kidneys.
___b. F-FDG localizes in the brain and heart muscle via a receptor mediated pathway on the cell
membranes responsible for transport of unlabeled glucose molecules from the blood.
Introduction to Radiation Biology – Exam III
November 11, 2010 Dr. Lattimer
For each of the following questions choose the one best answer from those provided at the bottom of
each page. Answers may be used once, more than once or not at all. Please put answers in the left
hand margin next to the question.
1. Free radicals reacting with DNA are the most common source of damage to the DNA by radiation.
Which of the choices is the compound or element which is the most frequent source of these free
2. DNA is one of the most complex molecules known. Which of the choices represents the subunit of
the cellular DNA which can be seen by light microscopy during cellular division?
3. Nearly all the DNA in the cell is located in the nucleus of the cell but there is a small amount of it
which is found outside the nucleus. Where is this small amount of DNA found?
4. Radiation induced injury to the DNA can result in numerous types of injury to the DNA. Which of the
choices is the type of injury which is most easily repaired by intranuclear repair mechanisms?
5. What category of DNA damage is that which could be enhanced or made more lethal by
6. Acentric fragments are examples of choromosomal aberrations arising from what type of damage?
7. What type of DNA injury which could result in loss of large amounts of DNA from the nucleus is
usually efficiently repaired by intranuclear repair mechanisms?
8. What type of DNA injury is usually accurately repaired only during S-phase of the cell cycle?
9. The initial straight portion of the cell survival curve seen at low doses is due to what type of DNA
a. Lethal damage f. Protien m. Base deletion
b. Potentially Lethal Damage g. Chromosome n. Single strand break
c. Sublethal Damage h. Chromatid o. Double strand break
d. Oxygen i. Gene p. mitosis
e. Water j. Golgi Body q. G1-phase
f. Nitrogen k. Mitochondria r. S-phase
e. DNA l. Nucleus q. G2-phase
10. Repair of DNA injury is generally considered to have the greatest effect during which phase of the
11. Repair of DNA injury is has the least effect during which phase of the cell cycle?
12. Which of the choices can improve the efficiency of DNA repair for a given total dose to the DNA?
13. In some instances the effect of DNA repair is also enhanced by what other process.
14. Reestablishment of the normal cell cycle phase proportions of a cycling cell population following
preferential killing of some phase of the cycle is referred to as what?
15. Cell populations with different cell cycle kinetics exhibit different apparent radiation responses.
Bone marrow stem cells are examples of which type of cell population according to Rubin and
16. Cells with have the potential to differentiate into other cell types to aid and promote repair of tissue
radiation injury are known as what types of cells.
17. Cells such a pneumocytes which are differentiated cells which have the ability to reproduce
themselves are members of what type of cell population according to Michaelowski?
18. Cell lines which must survive for a tissue and sometimes the organism to survive are called what?
19. Cell lines which typically exhibit strong repair capabilities are typically what type of cells?
20. Profound hypoxia at the cellular level is a potent promoter of what process?
21. In Vitro assays done with cell culture are typically examples of what type of cellular assay?
22. In Vivo assays involving implanting tissue from one animal to another are what type of assay?
a. Mitosis h. Repopulation o. Lethality
b. G1-phase i. Vegetative intermitotic p. Transplantation
c. G2-phase j Differentiating intermitotic q. Clonogenic
d. S-phase k. Multipotential connective r. Functional
e. Reassortment l. Reverting post mitotic s. Flexible cells
f. Repair m. Fixed post mitotic t. Critical cells
g. Reoxygenation n. In Situ u. Hierarchical
23. Erythema, edema and moist desquamation are examples of what type of tissue response to
24. Replacement of cells in a radiation field by cells of another type is an example of what type of tissue
25. Tissues for which the critical cell lines have long cell cycle times are referred to as what type of
26. Bone marrow and intestinal epithelium are considered to be what types of tissue with regards to
27. Hair loss and atrophy of fat in a radiation field are examples of what type of tissue response?
28. The cellular kinetics factor which favors recovery of a tissue following radiation exposure would be
29. Which of the cell types listed is considered to be most resistant to radiation injury?
30. Which of the cell types listed is considered to be the most sensitive to radiation injury?
31. Which of the cell types listed is responsible for recovery of skin following radiation injury?
32. Which of the cell types listed is considered to be the dose limiting cell in the GI tract?
33. Which of the reproductive cells listed is the most resistant to killing by radiation?
34. Which of the cell types listed below is especially susceptible to injury in teenagers and very young
a. Early responding h. Lymphocyte o. Hepatocytes
b. Late responding i. Pneumocytes p. Oocyte
c. Acute reaction j. Macrophage q. Crypt cells
d. Chronic reaction k. Basal Cells r. Bone marrow cell
e. Cellular Growth fraction l. Epithelial cells s. Cartilage cells
f. Cellular Loss fraction m. Germinal cells t. Erythrocyte
g. Blast cells n. Mucous cells u. Sperm cells
35. Which particulate radiation is of greatest concern with regards to whole body radiation exposure?
36. Which of the particulate radiations will result in the highest local dose equivalent to a tissue
37. The prodromal stage of a radiation syndrome is an example of what type of response to whole body
38. The Bone Marrow Syndrome usually causes death through which process?
39. The GI Syndrome usually causes death through what process?
40. Death is virtually a certainty after what dose of radiation to the whole body?
41. How long following a whole body irradiation would the Bone Marrow Syndrome reach a manifest
42. The period of organogenesis resulting in extreme organ system sensitivities to irradiation lasts
approximately how long in humans?
43. In the human fetus the central nervous system is at particular risk for approximately how many
weeks of the gestation?
44. Approximately how long after exposure to an antigen will a whole body irradiation dose of 1.0 Gy
not blunt the immune response to the body to that antigen.
45. Which type of radiation would be of particular threat to a developing embryo?
46. Blunting of the immune response to antigens has been demonstrated to occur in some experiments
at doses as low as?
47. In humans, a whole body radiation dose at which a bone marrow transplant would be expected to
improve survival would be?
a. photons i. 3 weeks q. 5 gray
b. neutrons j. 6 weeks r. 10 gray
c. alpha particles k. 18 weeks s. acute
d. Beta particles l. 39 weeks t. late
e. 1 day m. 0.1 gray u. infection
f. 4 days n. 0.5 gray v. anemia
g. 1 week o. 1.0 gray w. starvation
h. 2 weeks p. 3.0 gray x. dehydration
48. For the induction of cancer several criteria have to be satisfied. One of those criteria is up-
regulation of positive growth promoting factors within the cell. Which of these results in such a
positive growth promoting factor?
49. Cells which suffer a DNA mutation which causes them to die when they try to reproduce and are
removed from the cycling pool at the G1-S interface die by what mechanism?
50. Genes which encode for the repair of DNA damage are part of what general group of genes?
51. No matter the mechanism by which it occurs, tumor cells must escape certain controls on their
proliferation. What is the most fundamental control lost by any neoplastic growth?
52. Loss or reduced function of which general group of genes will promote the development of
53. In order for a mutated cell to develop into a cancer it must retain what capability.
54. Tumor cell populations possess what characteristic which is very different from the cell population
which they arise from?
55. What response to irradiation of a large neoplastic growth is virtually never seen in normal tissues?
56. Failure to control a tumor using radiation is due to what response of the tumor to the radiation
57. Radiation injury may result in either tumor cells or normal cells becoming part of the cycling cell
population where they were not before. This may happen for a variety of reasons. What is the term
which is used to indicate this process?
58. The use of multiple radiation treatments (fractions) is used with photon radiation principally due to
what process that occurs in cell populations following irradiation?
59. Using smaller fractions of radiation favors the survival of what type of tissues?
a. Late responding i. mutagenic activity q. Contact inhibition
b. Early responding j. clonogenic activity r. Cellular adhesion
c. Acute injury k. functional activity s. Apoptosis
d. Reoxygenation l. Proto-oncogenes t. Mitotic linked death
e. Reassortment m. DNA stability genes u. Immunological attack
f. Repair n. Tumor suppressor genes v. revascularization
g. Repopulation o. Phenotypic diversity w. metastasis
h. Recruitment p. Genetic diversity x. Hypoxia
60. Use of High LET radiation for treatment of cancer would be most valuable for treatment of tumors
have large numbers of cells exhibiting what characteristic?
61. High LET radiation also is a powerful suppressor of what process?
62. Chemotherapeutic agents in combination with radiation are most likely to have the most dramatic
effect on what types of tissue?
63. Drugs which improve blood flow to a tumor would promote what process?
64. In general, the radioprotectant Amiphostine enhances survival of what types of tissues?
65. High energy protons and electrons are considered to be what type of radiation?
66. Hyperthermia could be used to enhance cell killing in tumors if it could be limited to the tumor
because it inhibits what process?
67. Administration of what type of radiation therapy can result in very high doses of radiation to a
tumor with minimal to very little dose to the surrounding normal tissues?
66. Hyperthermia is synergistic with radiation because its effect is not blunted by what condition?
67. Reducing the normal tissue dose to ½ of the tumor dose should theoretically reduce the normal
tissue effects relative to the tumor by a factor of how much?
68. If a dose of 1.5 gray kills 50% of the cells in a population each time it is given, how many doses
would it require to reduce the number of cells in the population by >99% assuming no repopulation?
69. With regards to carcinogensis due to low dose, low dose rate radiation exposure, doubling the dose
increases the probability of a radiation induce neoplasm by what factor?
70. The radioprotective effect of hypoxia occurs principally below how many mmHg of oxygen tension?
71. High LET radiation would have the most profound effect on cells in what part of the cell cycle?
72. What type of radiation therapy would be best suited to treating a small deep seated brain tumor
located next to the visual cortex of the brain?
a. 1 i. Repair q. teletherapy
b. 2 j. Reoxyengenation p. brachytherapy
c. 3 k. Reassortment q. neutron therapy
d. 4 l. Repopulation r. proton therapy
e. 5 m. Early responding s. High LET
f. 7 n. Late responding t. Low LET
g. 10 o. hypoxia u. Mitosis
h. 20 p. heterogenous genotype v. S-phase
Introductory Radiation Biology
Final Exam, 2010
1. A radiation worker received a whole body dose of 100 mrads from fast neutrons
(QF = 20) as a result of an accident.
a. Calculate the Equivalent Dose (in mrem units) this worker received.
b. The Equivalent Dose in mSv units is __________ mSv.
c. The Absorbed Dose in Gy units is ________________Gy
2. a) According to the BEIR and UNSCEAR reports, it has been estimated that
approximately ____________________ radiation induced cancer deaths will occur in a
population of 1 million people receiving a whole body radiation dose (from gamma-rays)
of 1 rem each.
b) Using this risk estimate and assuming the linear-non-threshold extrapolation
approach, calculate the number of cancer deaths that would be produced by exposure
of a group of 20,000 people to a whole body dose (from gamma-rays) of 50 rem each
c) According to current epidemiology studies, approximately the percent of our
population who will die from “spontaneous” cancers is __________________. Thus, in
this group of 20,000 persons, approximately ______________ people are expected to
die from cancer from “spontaneous” cancers (i.e., assuming they do not receive the 50
rem exposure as stated in part b of this question].
3. Briefly define or describe (can use sketches when applicable)
a) Linear, Non-threshold Extrapolation method
b) Oxygen Effect
c) Free Radical
d) Double-strand breaks in the DNA
c) At least two sources of “Natural” background radiation
4. Radiation exposure of animals and humans will produce “Non-Stochastic Effects” at
higher radiation doses.
a) Describe what is meant by the term “Non-Stochastic” and give an example of a
property of “Non-stochastic Effects” that will differentiate them from “Stochastic
b) Give two examples of “Non-Stochastic Effects” that are be produced by ionizing
radiation in animals and humans
c) Give two examples of “Stochastic Effects” that are produced by ionizing radiation in
animals and humans.
5. a) Sketch what a “Cell Survival Curve” will look like if human kidney cells are irradiated
at a high dose rate, under 150 mrem Hg O2 with 1 MeV gamma rays. Label the X-axis
and Y-axis with appropriate units.
b) If these cells receive a radiation dose to produce a “D5”, the percent of the cells
remain alive (i.e., survive) at the D5 dose is ____________%.
6. Explain why epidemiology studies are able to demonstrate radiation exposure to
humans, will produce a “statistically” measurable increase in thyroid CA incidence at
lower doses (e.g., in the 10-30 rad to the thyroid) compared to radiation induced by lung
cancers (e.g., usually in the range of 50-100 rad doses to lungs).
7. a) Briefly explain why 131I-iodide, present in the fallout from an A-Bomb explosion, will
be taken up by the thyroid gland of humans following ingestion of food or liquids
contaminated with 131I-iodide.
c) The major fraction of the radiation dose to the thyroid gland from 131I located in
thyroid tissue is from the ____________ emitted during the decay of 131I.
a. beta particles
c. alpha particles.
b) Repeated epidemiology studies demonstrate that human adult patients treated for
hyperthyroid disease in 5-10 mCi of 131I-soduim iodide (producing an approximately 50-
100 Gy dose to the thyroid gland) results in a significant increase in thyroid cancer in the
patients later in life, when compared to patients with hyperthyroid disease treated
surgically (i.e., not administered 131-I-sodium iodide (TRUE or FALSE).
8. a) List three types of effects produced by excessive in utero radiation of the embryo or
fetus in the first trimester of humans or mammals.
b) The approximate in utero dose of gamma or x-radiation dose to the fetus in the first
trimester that will first produce a significant increase of serious congenital
malformations in newborn babies, relative to the spontaneous (background) rate of
congenital malformations in the U.S. population is approximately 15 rads
(TRUE or FALSE).
c) The “spontaneous” (background) rate of babies born with serious congenital malformation
in the U.S. is approximately:
i) 2% ii) 5% iii) 15% iv) 25%
___ a) The rate of production of radiation-induced hereditary effects (i.e., # of genetic
defects/rem) is currently estimated to be about the same, or perhaps lower,
than the rate of production of radiation-induced cancer deaths (i.e., # cancer
deaths/rem) in the U.S. population.
___ b) The base excision repair process is more effective in repairing DNA damage to
is exposed to 1 MeV protons compared to when human cells irradiate with 1
___ c) Thyroid cancer is more readily induced (i.e., # cancers induced/rad) by ionizing
radiation (e.g., 131I) in young children compared to adults.
___ d) There are no unique types of cancers in humans induced by ionizing radiation,
i.e., they all also occur “spontaneously” in the U.S. population.
___ e) The epidemiology studies of A-Bomb survivors have been able to demonstrate a
significant increase in some radiation-induced cancers in this population. In
contrast, epidemiology studies in this A-Bomb survivor population have not been
able to demonstrate an increase in radiation-induced genetic effects.
___ f) There are no unique types of congenital malformations found in human babies
induced by ionizing radiation, i.e., all congenital malformations induced by
ionizing radiation also occur “spontaneously” in the U.S. population.
INTRODUCTORY RADIATION BIOLOGY 328
FINAL EXAM QUESTIONS 2010—Michael R. Lewis, Ph.D.
1. Rank the following ionizing radiations in order of increasing ability to penetrate soft
tissue (i.e., beginning with the smallest range or depth of penetration; e.g., a < b < c < d,
but please note that this may or may not be the correct answer!).
a. 62 keV x-ray
b. 8 MeV alpha particle
c. 635 keV positron
d. 15 MeV electron
2. Promethium-149 (14961Pm; T1/2 = 53 h) decays to 14962Sm (stable). In 96.9% of events, 149Pm
decays to the ground state of 149Sm, while in 3.1% of events, it decays to an excited state of
Sm that lies 286 keV above the ground state.
a. Sketch a decay scheme that is consistent with this information.
b. True or False (circle one): 149Pm decay can be imaged using a gamma camera.
c. True or False (circle one): 149Pm is potentially useful for radionuclide therapy.
d. In his laboratory, Dr. Mike Lewis has been evaluating 149Pm radiopharmaceuticals for
cancer. He has planned an experiment for 1 pm on Wednesday and has ordered
delivery of 100 mCi of 149Pm produced at the MU Research Reactor (MURR). Assuming
that no 149Pm is lost during purification and processing, how much 149Pm has to be
present at the end of irradiation at 8 am on Monday, in order for MURR to fill Dr. Lewis’s
3. Briefly define or describe (no more than 1-2 sentences):
a. The type of radiation that most nuclear medicine (i.e., scintillation or Anger) cameras
b. Mean free path
c. Henri Becquerel
d. The predominant mode of 18F decay
e. The most biologically relevant mechanism by which ionizing photons interact with soft
tissue (HINT: predominates in the energy range of 100 keV to 10 MeV)
f. An element discovered by Pierre and Madam Marie Curie
g. Wilhelm Conrad Röntgen
h. Ionizing radiation
4. _____A 4 MeV x-ray photon will have lower LET and cause less biological damage over its track
in the body than a 4 MeV alpha particle.
5. _____99mTc emits a gamma ray during its decay, which makes it highly useful for cancer therapy.
6. _____Radionuclides produced by charged particle accelerators generally decay by electron
capture and/or positron emission, making them potentially useful for diagnostic imaging.
7. Imaging using Na131I is often performed for
a. diagnostic reasons only.
b. detecting osteosarcoma, metastatic prostate cancer, and other bone tumors.
c. planning radionuclide therapy of differentiated thyroid cancer.
d. all of the above.
e. none of the above.
8. In what tissues would you expect high accumulations of [18F]Fluorodeoxyglucose (18F-FDG)?
d. all of the above
e. none of the above
9. In order to determine whether a patient with skeletal metastases from prostate cancer is a good
candidate to use 153Sm-EDTMP (QuadraMet™) for pain relief, the appropriate diagnostic test is
a. imaging with Na131I.
b. imaging with 11C-Raclopride.
c. imaging with 99mTc-MDP.
d. imaging with 18F-FDG.
e. determining how high the patient can bounce on a trampoline.
10. In nuclear medicine, the emerging “gold standard” for diagnosing and/or determining the extent
of several types of cancer is
Final Examination questions for Radiation Biology 2010 – Dr. Lattimer
1. What is the principal means by which neutrons and other high LET radiation damage the DNA?
a. Direct ionization of a portion of the DNA molecule
b. Indirect damage by free radical species arising from interaction with oxygen
c. Indirect damage by free radical species arising from interaction with water
d. Direct collisional interaction with atoms in the molecule disrupting chemical bonds
e. Secondary ionization of the molecule by recoil electrons from collision with water
2. Which of the following will result in the greatest improvement in repair of ionizing radiation
induced DNA damage?
a. Long (weeks to months) period of time between radiation exposures.
b. Irradiation occurring during the G1 phase of the cell cycle
c. Very low dose rate
d. Low total dose
e. Irradiation with low energy photons
3. The presence of a broad shoulder on the cell survival curve for ionizing radiation injury to a
population of cells is and indication of which of the following?
a. The individual cells have long cell cycle times
b. The individual cells have good repopulation (clonogenic) potential
c. The individual cells have different sensitivities to radiation injury
d. The individual cells have good damage repair capabilities
e. The individual cells are genetically and phenotypically diverse
4. Cell death principally occurs when cells in their reproductive cycle reach one of two points in the
cell cycle. What are these two points which we talked about in class?
a. S-G2 phase interface and Mitosis
b. Mitosis and G1
c. G1-S phase interface and S-G2 phase interface
d. G1 and S phases
e. G1-S phase interface and Mitosis
5. Which of the following groups of cell types represent all F-type cell population according to the
a. Intestinal crypt cells, Basal cells, bone marrow stem cells
b. Plasma cells, endothelial cells, hepatocytes
c. neurons, fibroblasts, Basal cells
d. skin epithelial cells, erythrocytes, oral mucosal cells
e. Bone osteocytes, intestinal crypt cells, oocytes
6. The cell survival curve reflects three different segments which refer to three different types of
DNA injury, they are?
a. Repairable injury, Potentially repairable injury and no injury
b. Non-repairable injury, lethal injury and non-lethal injury
c. Single strand breaks, Double strand breaks and base pair deletions
d. Non repairable single hit injury, repairable injury and non-repairable multi-hit injury
e. Single hit injury, double hit injury, multiple (greater than 2 hit) injury
7. Given the survival curve depicted what type of assay was performed
d. In Vitro
e. In Situ
8. Which of the following would not be expected to affect the response of a tissue to a radiation
a. The volume of tissue irradiated.
b. The presence of hypoxic cells in the tissue
c. The type of radiation
d. The dose rate.
e. The source of the radiation
9. Which organ system is at particular risk in humans relative to other species.
a. Intestinal tract
b. Bone marrow
c. Central nervous system
10. Low doses of radiation (0.1-0.5Gy) to a fetus probably have the greatest mutagenic potential
during what period of gestation in humans?
a. 0-2 weeks
b. 2-6 weeks
c. 6-10 weeks
d. 10-14 weeks
e. 35-39 weeks
11. With respect to the potential for carcinogenesis and increased risk for neoplastic disease
induction, doubling the whole body dose to an individual above the accepted maximum
allowable dose would increase the probability of cancer induction by what factor.
12. When doing radiation therapy or any time when radiation is administered or received for any
reason, fractionating the dose is beneficial. Which of the following is the principal reason that
this is done in radiation therapy?
a. Decrease early responding tissue effects
b. Decrease late responding tissue effects
c. Increase early responding tissue effects
d. Increase late responding tissue effects.
e. b and c above
13. When fractionating dose, increasing the dose per fraction while keeping the total dose and the
total time over which the dose is administered constant, what is the generally accepted effect of
reducing the dose per fraction and increasing the number of fractions?
a. Increased late effects and decreased scarring of the tissue
b. Decreased late effects and decreased scarring of the tissue
c. Increased early effects and decreased scarring of the tissue
d. Decreased early effects and increased scarring of the tissue
e. Increased early effects and increased scarring of the tissue