Name: ___________________________________
INTRODUCTORY RADIATION BIOLOGY 7328/4328
FINAL EXAM QUESTIONS 2012—Michael R. Lewis, Ph.D.
SHOW ALL WORK!!!
1.
Rank the following ionizing radiations in order of increasing LET (i.e., beginning with
the lowest LET; e.g., a < b < c < d < e, but please note that this may or may not be the
correct answer!).
a.
b.
c.
d.
e.
2.
500 keV alpha particle
4 MeV positron
500 keV beta minus particle
62 keV x-ray
8 MeV alpha particle
Oxygen-15 (158O; T1/2 = 2 min) decays to 157N (stable) with emission of a charged
particle, no photon emissions from the nucleus, and a decay energy (Q) of 1.72 MeV.
a.
Sketch a decay scheme that is consistent with this information.
b. True or False (circle one): 15O decay can be imaged using a PET scanner.
c.
True or False (circle one): 15O is useful for radionuclide therapy.
d.
Dr. Mike Welch at Washington University in St. Louis was a pioneer in the
development of 15O radiopharmaceuticals. Many years ago, before modern
regulations existed, he used to produce 15O-oxygen on the cyclotron at Wash U’s
“Hilltop” campus, drive 10 minutes to the School of Medicine, and study a rat
after it breathed 2 mCi of 15O-oxygen. Assuming it took another 6 minutes to
prepare the rat, how many mCi of 15O-oxygen did Dr. Welch have to make on the
cyclotron to perform this study?
Name: ___________________________________
3.
Briefly define or describe (no more than 1-2 sentences):
a.
The type of radiation that Anger cameras or SPECT scanners detect
b.
Ionizing radiation
c.
Wilhelm Conrad Röntgen
d.
LET
e.
The most commonly used radionuclide for scintigraphy or SPECT imaging
TRUE/FALSE
4.
_____A 500 keV beta minus particle will have higher LET over its track and greater
relative biological effectiveness (RBE) than a 500 keV alpha particle.
5.
_____131I is used to treat thyroid diseases like well differentiated thyroid cancer.
6.
_____SPECT imaging is performed by rotating detectors around patients, while PET
imaging is performed by surrounding patients with a circular array of detectors.
Name: ___________________________________
MULTIPLE CHOICE
6.
If a patient shows high uptake of 99mTc-MDP in bone tumors, he or she is potentially a
good candidate for therapy with
a.
Na131I (sodium iodide).
153
b.
Sm-EDTMP (QuadraMet™).
201
c.
TlCl (thallium chloride).
d.
all of the above.
e.
none of the above.
7.
[18F]Fluorodeoxyglucose (18F-FDG) accumulates predominantly in tissues with high rates
of glucose metabolism, such as
a.
muscle.
b.
brain.
c.
tumors.
d.
all of the above.
e.
none of the above.
8.
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) is
a.
the photoelectric effect.
b.
Compton scattering.
c.
pair production.
d.
positron annihilation.
e.
spontaneous fission.
Dr. Bryan’s final exam questions
2012
Name_______________________
Read each question carefully before answering. Show work to receive potential partial
credit.
Identify your answer clearly.
1)
a)
b)
c)
d)
Which of the following is a stochastic risk?
Cataract development from radiation
Drowning
Mental retardation at birth
Skin erythema following radiation exposure
2) Among the reasons that absolute risk of cancer development due to radiation exposure is
difficult to determine in a population is that:
a)
b)
c)
d)
Radiation-induced cancers are no different than cancers from other causes
Radiation causes such a large proportion of observed cancers
Radiation exposure is rare in the general population
Cancers are generally quite rare events in the population
Name: ___________________________________
3) Compared to cancer events following radiation, which of the following can be said of
genetic/heritable diseases caused by cancer:
a) While unlikely to develop cancer, children exposed in utero have a high rate of birth defects
b) Radiation is very efficient at causing lesions that will become genetic defects, particularly at
high doses
c) Neither cancers nor birth defects are likely after low-dose radiation exposure
d) Birth defects in the F1 generation were the most commonly seen after-effect in atomic bomb
survivors
4) Match the potential effects of exposure to low-dose radiation during each phase of pregnancy
with the phase listed below. Each answer may be used more than once.
_____Preimplantation
a) Congenital malformation
_____Implantation
b) Death
_____Organogenesis
c) Intrauterine growth retardation
_____Fetal period
d) Mental retardation
5) In the cell survival curve above, please select the letter that best represents each of the
concepts below. Each letter may be used more than once.
Name: ___________________________________
_____Quadratic portion of the curve
_____Extrapolation number
_____Single-hit cell killing
_____Repair shoulder
1
2
3
4
DOSE
5
6
7
6) In the cell survival curve above, please calculate the following values:
D37:
D0:
7) The Veterinary Medical Teaching Hospital is installing a new linear accelerator for cancer
therapy. The machine will emit 15MeV x-rays for therapy. Environmental Health and Safety
Name: ___________________________________
wants the beam to be attenuated 85% with new lead shielding before it reaches the existing wall.
If the half-value layer of lead for 15MeV x-rays is 3cm, how many cm of lead will be needed?
a) 0.49 cm
b) 0.70 cm
c) 5.69 cm
d) 8.21 cm
8) If an α++ has an LET of 500 keV/µm, what would be the approximate LET of a proton of the
same energy?
a)
b)
c)
d)
31.25 eV/µm
62.5 keV/µm
125 keV/µm
250 keV/µm
9) A radiation worker at the Chernobyl power plant receives a dose of 200 Rad of fast neutrons
and 300 Rad of high-energy gamma rays during the core breach. If the RBE of neutrons (quality
factor) is 10, which of the following is the total exposure this man received?
a)
b)
c)
d)
23 Sv
32 mSv
500 Sv
500 mSv
10) Fill in the steps for base excision repair using the following enzymes (you may use each
more than once):
a)
b)
c)
d)
DNA Ligase
DNA Polymerase
Endonuclease
Glycosylase
Base excision repair occurs by the following process: the damaged base is removed by
________. The backbone of the DNA strand is then cut by _________. The removed backbone
and base are then replaced by ___________. Finally, the strand is re-annealed by __________.
11) Of 105,427 survivors of the atomic bomb blasts in Japan who were followed from 1958
through 1998, how many developed solid tumors cancers secondary to the radiation exposure?
a)
b)
c)
d)
No additional cancers were seen
853 cancers were attributed to the exposure
10,439 cancers were attributed to the exposure
49,923 cancers were attributed to the exposure
Name: ___________________________________
Gy of Radiation
12) What is the effective D0 for this fractionated radiation scheme?
a)
b)
c)
d)
1.4 Gy
1.8 Gy
2.2 Gy
5.6 Gy
13) A researcher discovers that daily McDonalds Sweet Tea intake is associated with a risk of
stomach cancer in rats due to the presence of trace radioactive elements. If the following are
true, what is the estimated number of attributable cases of stomach cancer for a group of 40,000
people followed for five years who drink McDonalds Sweet Tea daily over the course of the
study period?
Stomach cancer strikes 8 out of 100,000 people each year
20 of the Sweet Tea drinkers got stomach cancer during the study period
None of the participants possessed any other known risk factors for stomach cancer
a) There were 20 fewer cancers than expected for this group over the study period
b) There were 4 more cancers than expected for this group over the study period
c) There were 20 more cancers than expected for this group over the study period
d) Stochastic risks cannot be estimated from clinical studies
14) Which DNA repair process is most important in the repair of dipyrimidine dimers (T-T
dimers) caused by UV light?
Name: ___________________________________
a)
b)
c)
d)
Base excision repair
Homologous recombination repair
Non-homologous end-joining
Nucleotide excision repair
15) If a dose of 10 Gy of 250 kVp x-rays is necessary to reduce the surviving fraction of cells in
a culture plate to 1% (0.01 of original cells), and the RBE of neutrons under these conditions is
10, what is the dose of neutrons necessary to have the same effect?
a)
b)
c)
d)
0.1 Gy
1 Gy
10 Gy
100 Gy
16) For which of the radiation exposures below would the OER for Chinese hamster ovary cells
irradiated in room air at a constant dose-rate be 1?
a)
b)
c)
d)
5 MeV x-rays
7 MeV electrons
500 keV α++ particles
900 KeV β- particles
Name: ___________________________________
17) Using the curves drawn above, answer the questions below:
___ The curve that represents cell killing from a high LET form of radiation.
18) Considering curves B and C, if these two curves represent the same cell system irradiated
with the same type of radiation under differing experimental conditions, which of the following
statements is true?
a)
b)
c)
d)
Curve C was irradiated at a higher dose-rate than Curve B
Curve C was irradiated with significantly less oxygen present than Curve B
More sulfhydryls (-SH) were present in the system for Curve B than for Curve C
The cells in Curve C appear more radiosensitive than the cells in Curve B
19) For which curve is the killing of cells predominantly by a one-hit process?
a) Curve A
b) Curve B
c) Curve C
20) Which two curves have approximately the same D0?
a)
b)
c)
d)
Curves A and B
Curves B and C
Curves A and C
D0 differs for each curve
Final exam questions: Dr. Lattimer
1.
Which of the following represents the principal means by which DNA is injured by
ionizing radiation?
a.
Direct interaction of the radiation with the base pairs of the DNA
b.
Direct interaction of the radiation with the side strands of the DNA
c.
Indirect action of recoil oxygen on the DNA side strands after ionization of water
d.
Indirect action on the Sulfhydrl cross-linking of the DNA by reactive oxygen
species
e.
Indirect action on the DNA strands and base pairs by reactive OH- species.
2.
Injury to which of the following cell types is likely to result in the least demonstrable cell
death?
a.
Vegetative intermitotic cells
b.
Differentiating intermitotic cells
c.
Mulipotential connective tissue cells
d.
Reverting Post Mitotic cells.
e.
Fixed Post Mitotic cells.
Name: ___________________________________
3.
4.
5.
6.
7.
Which of the following organs is most susceptible to radiation injury?
a.
Lung
b.
Liver
c.
Heart
d.
Spinal Cord
e.
Bone
The phase of organogenesis is the period of fetal development during which irradiation
has the highest potential to cause birth defects. Organogenesis ends at the end of which
of the follow weeks post conception in humans?
a.
4th week
b.
6th week
c.
8th week
d.
8th week
e.
10th week
Which of the following is a radiation dose which is generally considered to represent a
dose below which no detectable radiation injury will occur?
a.
1 cGY
b.
5 cGy
c.
10 cGY
d.
25 cGy
e.
50 cGy
Which of the following types of assays would be most likely used to study the effect of a
dose of radiation the metastatic potential of a given tumor type in mice.
a.
in vitro Clonogenic assay
b.
in vivo Clonogenic assay
c.
in vitro Transplantation assay
d.
in vivo transplantation assay
e.
in vivo lethality assay
With respects to the reaction of tissues and tumors to a dose of radiation, which of the
following is thought to only occur in tumors?
a.
Repair
Name: ___________________________________
8.
9.
10.
b.
Reoxygenation
c.
Regeneration
d.
Reassortment
e.
Recruitment
Which of the following types of radiation is most likely to result in a large amount of
non-repairable radiation injury for the same delivered dose?
a.
X-rays
b.
Gamma rays
c.
Electrons
d.
Protons
e.
Alpha particles
Which of the following represents an effect of fractionation of the radiation dose in
administration of radiation for treatment of cancer?
a.
Improves disease control to complication rate
b.
Decreases late effects in acutely responding tissues
c.
Decreases late effects in late responding tissues
d.
Improves tumor oxygenation
e.
All of the above.
Radiation treatment with protons has been gaining favor a means of treating cancer.
Which of the following is a major roadblock for a hospital wishing to start using this type
of treatment?
a.
Shielding requirements for the protons
b.
Limited number of cancers which can be treated
c.
Cost of the equipment and installation
d.
Difficulty in properly administering dose of radiation prescribed
e.
Increase number of late radiation effects.