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Washington & Leaver: Principles and Practice of Radiation Therapy,
3rd Edition
Chapter 04: Overview of Radiobiology
Additional Assignments
Define the following terms.
1. Mutation frequency:
2. Doubling dose:
3. Radiobiology:
4. Homeostasis:
5. Catabolism:
6. Anabolism:
7. Protein synthesis:
8. Macromolecule:
9. Target:
10. Free radical:
11. LET (identify & define):
12. RBE (identify & define):
13. Tissue culture:
14. SLD (identify & define):
15. PLD (identify & define):
16. Radiosensitivity:
17. Differentiation:
18. Parenchyma:
19. Stroma:
20. Assay:
21. LD50:
22. TD5/5:
23. LD50/30:
24. Somatic effects:
25. Stochastic:
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Additional Assignments
26. Nonstochastic:
Answer the following questions.
27. According to the Target Theory, what is the principal target of cell damage?
28. Briefly describe each component of mitosis.
Prophase:
Metaphase:
Anaphase:
Telophase:
Interphase:
29. Briefly describe each component of DNA synthesis.
S:
G1:
G2:
G0:
M:
30. Contrast direct action with indirect action.
31. Complete the reaction.
H2O + ionizing radiation →
32. Contrast in vivo and in vitro.
33. Contrast asynchronous populations with synchronous populations.
34. Contrast radiosensitivity and radiocurability.
35. Define direct and indirect radiation effects.
36. Describe the four Rs of radiation therapy.
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Additional Assignments
37. Describe mitotic delay.
38. Describe the relationship between LET and RBE.
39. Define radioprotectors and radiosensitizers.
40. During which cell cycle phase are cells most radioresistant and most radiosensitive?
41. Draw and label a typical survival curve.
42. Describe the relationship between genes, DNA, and chromosomes.
43. Describe the three possible outcomes of an irradiated cell.
44. Describe the major difference between the two types of tissue healing.
45. Define each of the following components of the mammalian survival curve.
D0
Dq
n
1D0 (aka D1)


46. How is growth fraction measured?
47. How and why is survival affected by changes in the dose rate?
48. Identify and describe the potential effects of radiation on DNA.
49. Identify and describe the potential effects of radiation on chromosomes.
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Additional Assignments
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50. If 300 cGy is required to reduce survival to 1% under aerobic conditions and 750 cGy
under hypoxic conditions, what is the OER?
51. If 2,000 cGy is required to produce alopecia in Chinese hamsters under normal
conditions and 3,500 cGy WR-2721 is administered prior to irradiation, what is the
DRF?
52. If it takes 500 cGy to reduce survival to 1% under aerobic conditions and 1,150 cGy
under hypoxic conditions, what is the OER?
53. If 55% of a tumor cell population is in the quiescent (nonproliferating) compartment,
what is the growth fraction?
54. If a total of 70 Gy is delivered in 35 fractions of 2 Gy, calculate the BED.
55. List and describe the three types of tissue response assays.
56. List and describe the five categories of cell populations as defined by Rubin and
Casarett.
57. List four potential somatic effects of radiation exposure.
58. List the three embryological divisions of pregnancy.
59. List four radiation-induced mutations of genetic material.
60. List the three functions of lipids.
61. Mouse tumors were irradiated with 2,000 cGy under normal air breathing conditions
with and without the tumor clamped to make it hypoxic. If the surviving fractions for
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Additional Assignments
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these two conditions are 0.004 (unclamped) and 0.02 (clamped), what is the hypoxic
fraction of this tumor under normal conditions?
62. What is the Law of Bergonie and Tribondeua? Why is it important in radiobiology?
63. What is the Law of Ancel and Vitemberger? Why is it important in radiobiology?
64. What are parenchymal cells?
65. Why is the small bowel the most radiosensitive organ of the GI tract?
66. What is maturation depletion?
67. Who conducted experiments with fruit flies and determined that radiation increased
the mutation frequency but did not cause unique mutations?
68. What is the diffusion distance of oxygen in a tissue?
69. What is thought to be the target molecule for the lethal effects of radiation, and what
are four types of radiation-induced damages on it?
70. What type of radiation is used as a standard for determining the RBE?
71. Which type of radiation damage to the DNA is most likely lead to a permanent
mutation?
72. You are using the in vivo dilution assay to determine the survival of an irradiated
mouse tumor. If 5 cells from the control mouse tumor and 1,500 cells from the
irradiated mouse tumor (4 Gy) are required to produce a tumor in 50% of the
recipient mice (TD50 = 5 and 1,500), what is the surviving fraction after 4 Gy?
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Additional Assignments
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73. Given the following data, draw and label its cell survival curve.
Dose
Survival
0
100
200
80
600
30
800
12.5
1,200
2.20
1,400
1.00
Match the description to the correct cell cycle stage.
____74.
Most radioresistant
A. G1
____75.
Cells may accumulate after irradiation
B. S
____76.
Greatest variation in length
C. G0
____77.
Most radiosensitive
D. M
____78.
Cells are at rest
E. G2
Match the statement to the correct survival curve parameter.
____79.
Dose at which the linear and quadratic contributions to cell killing are equal.
A. 
____80.
Dq + D0
B. 
____81.
Dq/D0
C. 
____82.
Measure of the width of the survival curve shoulder
D. D0
____83.
Inversely proportional to the final slope
E. Dq
____84.
Thought to be related to the formation of double-strand DNA breaks
F. D37
____85.
Thought to be related to the formation of single-strand DNA breaks
G. log n
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Additional Assignments
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Match the item with the parameter it is used to measure. Answers may be used more than
once.
____86.
Courtenay soft agar assay
A. Proliferation potential
____87.
Cell adhesion matrix (CAM) assay
B. Reproductive
integrity
____88.
Tpot
C. Growth assay
____89.
Labeled nitroimidazoles
D. Oxygen status
____90.
Colorimetric microtiter well assay
____91.
Polarographic electrode
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