Deck 4: Overview of Radiobiology

Question 1

Populations that do not divide are generally radiosensitive.

Answer 1

False
Based on the Law of Bergonié and Tribondeau,cells that do not divide are radioresistant.

Question 2

Carbohydrates contain enzymes.

Answer 2

False
Carbohydrates and enzymes are both cellular components but neither is a component of the other.

Question 3

All tumors reoxygenate at the same rate.

Answer 3

False
Large tumors with smaller blood supplies will take much longer to reoxygenate compared to smaller tumors with good blood supplies.

Question 4

In deciding upon treatment protocol,tumor radiosensitivity is more important to consider than normal tissue radiosensitivity.

Question 5

Mitosis occurs in germ cells.

Question 6

D₀ is a good measure of SLD repair capacity.

Question 7

For a given particle,as its velocity increases,LET increases.

Question 8

BUDR is a radioprotector.

Question 9

In order to produce the same biologic effect as a single fraction of 5,000 cGy,the total dose of a fractionated treatment regimen will be greater than 5,000 cGy.

Question 10

Cellular response to high LET varies by dose rate.

Question 11

RBE relates to the ability of different radiation doses,energies,or types to produce a specific biologic response.

Question 12

Protons have higher LET than gamma rays.

Question 13

Equal doses of different types of ionizing radiation produce equal biological effects.

Question 14

Interval to completion of therapy or the total number of days a patient is under treatment is an important variable for local tumor control.

Question 15

Organ dose can be measured directly.

Question 16

Acute responding normal tissues manifest their injuries within a few months after irradiation.

Question 17

Cells are more radiosensitive when exposed to high LET radiation.

Question 18

Sublethal damage recovery can be measured in split-dose experiments.

Question 19

SLD repair increases with increasing LET.

Question 20

Acute side effects of treatment related ionizing radiation are exclusively due to the total volume of radiation treated.

Question 21

Which of the following terms describes the separation of water into hydrogen and oxygen following exposure to radiation?

A) radiolysis
B) radioactivity
C) ionization
D) Duplication

Question 22

Tumors that have a PO₂ less than 10 mm Hg have a poor prognosis.

Question 23

How does oxygen retention affect radiosensitivity?

A) increase
B) decreases
C) no change
D) varies by tissue

Question 24

What is the typical OER value for sparsely ionizing radiation?

A) 0.5 to 1.0
B) 1.0 to 2.0
C) 2.5 to 3.0
D) greater than 3.0

Question 25

What does the term interphase death mean?

A) Cell dies prior to entering interphase.
B) Cell dies prior to leaving interphase.
C) Cell dies between mitotic phases.
D) The entire organism dies.

Question 26

Isoeffect curves are most closely associated with which of the following?

A) oxygen enhancement
B) radiation syndromes
C) tolerance doses
D) fractionation

Question 27

Which macromolecule is most radiosensitive?

A) lipids
B) carbohydrates
C) proteins
D) nucleic acids

Question 28

The indirect action of radiation is mediated by the generation of DNA radicals.

Question 29

What is the term describing certain chemicals or drugs that enhance the response of cells to radiation?

A) free radicals
B) radiosensitizers
C) radioprotectors
D) NSAIDs

Question 30

The presence of oxygen increases the effectiveness of irradiation.

Question 31

The oxygen enhancement ratio is greater for densely ionizing radiation.

Question 32

Which of the following terms is used to describe radiation damage to a cell that is not sufficient to kill the cell?

A) RBE
B) SLD
C) TLD
D) LD_50/40

Question 33

Tumors have more SLD repair capacity than normal tissues.

Question 34

A whole body radiation dose given in a period of seconds to minutes produces a clinical pattern called what?

A) delayed effects
B) mortality rates
C) acute radiation syndromes
D) clinical body dose

Question 35

The greatest amount of energy is deposited as a charged particle,such as a proton,comes to rest.

Question 36

Which of the following is the most important treatment related variable for the development of late-term effects of ionizing radiation?

A) treatment volume
B) elapsed days
C) OER
D) dose

Question 37

Which of the following is not a pyrimidine?

A) adenine
B) cytosine
C) thymine
D) uracil

Question 38

To calculate the NSD (nominal standard dose),what factors must be known?
I)total dose
II)fraction size
III)elapsed days

A) I and II
B) I and III
C) II and III
D) I,II,and III

Question 39

Which of the following tissues is least radiosensitive?

A) bone
B) kidney
C) ocular lens
D) colon

Question 40

When cells are sensitized by oxygen,the resulting survival curve has a reduced extrapolation number.

Question 41

Which of the following cell types are likely to express radiation injury shortly after a D₀ dose of radiation is received? (Mark all that apply.)

A) VIM
B) DIM
C) RPM
D) FPM

Question 42

Which of the following is not an early response to radiation?

A) breast cancer
B) erythema
C) diarrhea
D) chromosome aberrations

Question 43

Fractionation of radiation dose administration to neoplastic tissues has which of the following effects? (Mark all that apply.)

A) reoxygenation of hypoxic tumor cells thus promote their sensitivity to subsequent
Doses
B) favors repair of radiation injury in normal cells over that of cancer cells
C) favors repopulation of normal tissues slightly
D) reduces or blunts the effects of the radiation injury in early responding normal tissues