Which of the following is NOT a component of the Law of Bergoni� and Tribondeau?
a. Actively dividing cells are less sensitive.
Which of the following groups of cells are correctly ranked in order of radiosensitivity beginning with the most sensitive?
b. Reproductive, bone, nerve, muscle
Continued exposure to radiation over prolonged periods may result in each of the following EXCEPT one. Which one is the EXCEPTION?
c. It may produce offspring with increased resistance to radiation exposure.
What is the approximate surface (skin) dose of radiation from a full mouth series of 18 F-speed films, exposed at 90 kVp with a 16-inch (41-cm)-length PID?
a. 30 mSv
Which of these periods immediately follows radiation exposure?
b. The latent period
When the severity of change is dependent on the radiation dose, the effect is called a/an:
b. deterministic effect.
At what dose of whole-body radiation would an observable short-term effect of acute radiation syndrome result?
d. 1.0 Gy
Tissues have the capacity to repair radiation damage to a certain degree. However, some damage
cannot be repaired and remains weakened, especially with repeated exposures. This is called:
c. a cumulative effect.
What theory of radiation damage to cells results from free radicals combining to form toxins such as hydrogen peroxide?
c. Indirect
A threshold dose-response relationship indicates that any dose, regardless of amount, can be expected
to produce a biologic response.
A linear dose-response relationship indicates that the biologic response is directly proportional to the
dose.
b. The first statement is false. The second statement is true.
Scientists do not know whether low levels of radiation exposure carry health risks.
True
A less specialized cell is more radioresistant.
False
A nonthreshold dose-response curve indicates that there is a certain level of radiation below which no biological response should be anticipated.
False
The ALARA concept means "As Low As Reasonably Achievable.
True
The effects of irradiation depend on the type of energy and duration of the exposure.
True
All humans have the same sensitivity to radiation.
False
All cells in the human body have the same sensitivity to radiation.
False
X-rays have been shown to have carcinogenic effects.
True
The structures of the oral and facial regions are relatively radioresistant.
True
The Law of Bergoni� and Tribondeau states that cells are most sensitive to radiation injury during mitosis (cell division).
True
The biological effects of very low levels of radiation cannot be predicted.
True
Radioresistant refers to those tissues that are protected by the lead apron and thyroid collar during a dental x-ray exposure.
False
The latent period refers to the time between exposure to radiation and the ionization of molecules.
False
When radiation affects any cells of the body except the reproductive cells, the effect is called indirect.
False
A stochastic effect is when a biological response is based on the probability of occurrence rather than the severity of the change..
True
Cancer is a stochastic effect of exposure to radiation.
True
Erythema is a stochastic effect of exposure to radiation.
False
Because they do not divide and are very specialized, reproductive cells are radioresistant.
False
White blood cells (lymphocytes) and reproductive cells (oocytes) are two exceptions to the Law of Bergoni� and Tribondeau, which states cells that do not divide and are very specialized are radioresistant.
True
The average effective dose equivalent from naturally occurring background radiation to the population of the United States is approximately 8 �Sv (microsieverts) per day.
True
Which of the following statements regarding the biological effect mechanisms of the direct theory is FALSE?
Irradiated cells cannot be repaired.
Which of the following statements regarding the biological effect mechanisms of the indirect effect is FALSE?
Ions have a strong tendency to seek out new combinations.
Which of the following is most sensitive to damage from radiation?
White blood cells
Which of the following statements about radiation repair is FALSE?
a. Somatic cells cannot repair radiation damage.
Which of the following statements regarding the theory established by a threshold dose-response curve is true?
a. There is a dose below which no biological response would be expected.
Each of the following is a potential effect of a low dose of radiation EXCEPT one. Which one is the EXCEPTION?
d. Cell becomes radioactive.
Which of the following statements regarding radiation injury is FALSE?
a. The smaller the area of tissue exposure, the greater damage to the individual.
Which of the following statements regarding radiation injury is FALSE?
b. The lethal dose (LD 50/30) for humans is 1.5 grays.
The lethal dose (LD 50/30) of radiation for humans is estimated to be:
d. 4.5 grays.
Which of these is NOT a symptom of acute radiation syndrome.
a. Constipation