Chapter 04: Radiation Biology
Iannucci: Dental Radiography, 5th Edition
MULTIPLE CHOICE
1. (1) All ionizing radiations cause damage to living tissues. (2) Although very little radiation is
used in dentistry, damage to the cells does occur.
a.
Both statements are true.
b.
Both statements are false.
c.
The first statement is true; the second statement is false.
d.
The first statement is false; the second statement is true.
2. What specific mechanism of radiation injury may result in the formation of hydrogen peroxide
when x-ray energy is absorbed by patients?
a.
An ejected high-speed electron may interact with other atoms within absorbing
tissues.
b.
Free radical formation created by the ionization of water may occur.
c.
Unequal charge distribution may result in negative electrical potential.
d.
Creation of a magnetic field may cause polarization.
3. Which of the following statements is true regarding the direct theory of radiation injury?
a.
It involves absorption of an x-ray photon by water within a cell.
b.
It involves the formation of toxins that damage the cell.
c.
It involves damage to the critical areas of a cell through direct contact with the
x-ray photon.
d.
It involves the formation of free radicals.
4. The indirect theory proposes that
a.
toxins are created from the formation of free radicals.
b.
ionizing radiation strikes critical areas within cells.
c.
direct injuries occur more frequently than indirect injuries.
d.
changes occur to the deoxyribonucleic acid (DNA) of a cell.
5. According to the dose-response curve, when dose and damage are plotted on a graph, a
_____________________ relationship is seen.
a.
nonlinear, nonthreshold
b.
linear, nonthreshold
c.
nonlinear, threshold
d.
linear, threshold
6. A nonthreshold dose-response curve suggests that
a.
radiation exposure below the threshold will not damage tissues.
b.
radiation exposure below the threshold is safe for living tissue.
c.
radiation exposure above the threshold amount causes some damage to tissues.
d.
radiation exposure, no matter how small, causes damage to living tissue.
7. Stochastic biologic effects from radiation
a.
are directly related to exposure and effect.
b.
occur as a result of exposure, but severity is not determined by dose.
c.
have a dose threshold.
d.
cause significant damage to cell or cell death.
8. Which of the following is an example of stochastic effects?
a.
Erythema
b.
Cancer
c.
Hair loss
d.
Radiation sickness
9. Your patient was out in the hot, bright sun yesterday. While in the sun she began experiencing
pain and noticed her skin had turned bright red. Shortly after arriving home, she began to
experience chills, nausea, severe pain, and blistering. Why would your patient experience the
symptoms so quickly?
a.
The latent period was decreased by the increased dose and dose rate.
b.
The latent period was increased by the increased dose and dose rate.
c.
The latent period was decreased by the increased area of tissue irradiated and the
number of sensitive cells.
d.
The latent period was not affected.
10. Cellular injuries following the latent period may include (1) cell death, (2) cessation of mitotic
activity, and/or (3) abnormal mitotic activity.
a.
1, 2, 3
b.
1, 2
c.
1, 3
d.
1 only
11. ___________ refers to the total amount of radiation that is received or absorbed.
a.
Total dose
b.
Dose rate
c.
Amount of tissue irradiated
d.
Cell sensitivity
12. (1) More radiation damage takes place with high dose rates (2) because a rapid delivery of
radiation does not allow time for cellular damage to be repaired.
a.
Both statements are true.
b.
Both statements are false.
c.
The first statement is true; the second statement is false.
d.
The first statement is false; the second statement is true.
13. Which types of cells are more sensitive to radiation: (1) rapidly dividing, (2) slowly dividing,
(3) young, and/or (4) old?
a.
1 and 3
b.
1 and 4
c.
2 and 3
d.
2 and 4
14. Which of the following is associated with long-term radiation effects?
a.
Symptoms include diarrhea, hair loss, and hemorrhage.
b.
Small amounts of radiation absorbed over a long period
c.
Acute radiation syndrome
d.
The injury period in the sequence of radiation injury is seen within minutes, days,
or weeks of radiation exposure.
15. Which of the following is a sign or symptom of acute radiation syndrome (ARS)?
a.
Genetic defects
b.
Birth abnormalities
c.
Hair loss
d.
Cancer
16. Which of the following statements is true of somatic effects of irradiation?
a.
Changes are not transmitted to future generations.
b.
Changes are in the genetic cells of the individual.
c.
Mutations occur that affect the health of offspring.
d.
Damage cannot be repaired.
17. Which of the following cells would be the most sensitive to x-rays?
a.
Nerve
b.
Bone
c.
Muscle
d.
Blood
18. Which of the following is the least sensitive to x-rays?
a.
Bone marrow
b.
Salivary glands
c.
Lymphoid tissue
d.
Intestines
19. Precautions should be taken during dental imaging procedures to which of the following
critical organs in the head and neck region? (1) skin, (2) thyroid gland, (3) lens of the eye, and
(4) bone marrow
a.
1, 2, 3, 4
b.
1, 2, 3
c.
1, 2, 4
d.
2, 4
20. The traditional unit of dose is called
a.
the roentgen (R).
b.
the radiation absorbed dose (rad).
c.
the roentgen equivalent in man (rem).
d.
the gray (Gy).
21. One gray is equivalent to ______ rad(s).
a.
1
b.
10
c.
100
d.
1000
22. The SI equivalent of the rem is
a.
the rad.
b.
the gray.
c.
the sievert.
d.
the roentgen.
23. You could be exposed to each of these radiation sources in your daily activities. Which of
these sources is human-made?
a.
Radon gas
b.
Atomic fallout
c.
Terrestrial radiation
d.
Radioactive potassium
24. Uranium is an example of __________ radiation.
a.
terrestrial
b.
cosmic
c.
artificial
d.
internal
25. ________________ is/are the single largest contributor to artificial radiation exposure
(0.00053 Sv/year).
a.
Consumer products
b.
Medical radiation
c.
Fallout from atomic weapons
d.
The nuclear fuel cycle
26. Which of the following statements is true of the average dose of background radiation
received by an individual in the United States?
a.
The average dose of background radiation a person living in the United States
receives each year is 6.2 mSv.
b.
Geographic areas at higher elevations are associated with increased amounts of
cosmic radiation.
c.
Geographic areas that contain more radioactive materials are associated with
increased amounts of cosmic radiation.
d.
A wood home has a higher natural radiation level than a brick home.
27. The potential risk of dental radiography inducing a fatal cancer in an individual is about
_________ the risk of a person developing cancer spontaneously.
a.
1/10
b.
1/100
c.
1/1000
d.
1/1,000,000
28. A 1 in 1 million risk of a fatal outcome is associated with which of the following activities?
a.
Riding 10 miles on a bike
b.
Riding 300 miles in an auto
c.
Riding 1000 miles in an airplane
d.
All three of the above activities
29. Risk estimates suggest (1) that death is more likely to occur from common activities than from
dental imaging procedures and (2) that cancer is much more likely to be unrelated to dental
imaging radiation exposure.
a.
Both statements are true.
b.
Both statements are false.
c.
The first statement is true; the second statement is false.
d.
The first statement is false; the second statement is true.
30. The use of F-speed film instead of D-speed film reduces the absorbed dose by ____%.
a.
10
b.
25
c.
50
d.
60
31. Your patient is concerned about radiation exposure. Which of the following explanations
would you give to your patient to help calm her concerns?
a.
I will be using a digital sensor; this will reduce x-ray exposure by 30% over the
use of conventional film.
b.
I am using this collimator attachment, which will decrease the x-ray dose you
receive by 60-70%.
c.
I will be using the bisecting technique for receptor placement, which will reduce
exposure.
d.
A sign of excessive radiation exposure to the skin is reddening or erythema. I
would have to take more than 30 exposures using film, not digital, during a 14-day
period to cause reddening. I will only be taking 20 digital x-rays.
32. Which of the following combinations will result in the lowest absorbed dose for the patient
from a 20-film series of dental radiographs?
a.
Round collimation with digital sensor
b.
Rectangular collimation with digital sensor
c.
Round collimation with F-speed film
d.
Rectangular collimation with F-speed film
33. Your patient is receiving radiation treatments for breast cancer. She reports having a burning
sore throat and great difficulty swallowing. Which stage of the radiation injury sequence is
your patient in?
a.
Injury
b.
Recovery
c.
Latent
d.
Cumulative effects
34. Your patient is concerned about being exposed to dental x-rays. Which of the following could
you tell your patient to alleviate her fears?
a.
We take x-rays once a year, it is safe, and that is all your insurance will pay for.
b.
Your risk of getting cancer from dental x-rays is only 2 times greater than getting
cancer spontaneously.
c.
The risks from dental imaging are not significantly greater than the risks of other
everyday activities in modern life.
d.
Three fourths of the radiation exposure you will have throughout your life will
come from background radiation.
35. Explain to your patient the steps, in order, in the formation of hydrogen peroxide, a toxin that
will cause damage to living tissues.
1. Free radicals combine
2. Free radical formation
3. Cellular dysfunction and biologic damage
4. X-ray photons are absorbed by water
a.
1, 2, 3, 4
b.
4, 2, 1, 3
c.
2, 1, 4, 3
d.
2, 4, 1, 3
36. The bombing at Nagasaki and Hiroshima took place in 1945; an increase in the incidence of
cancer was noted in 1956. Which effects apply to the cancer incidence?
a.
Short-term, somatic
b.
Long-term, somatic
c.
Short-term, genetic
d.
Long-term, genetic