Chapter 5: Effects of Radiation Exposure

d

Which of the following statements regarding the biological effect mechanisms of the direct theory is false?

A) Most dental x-ray photons pass through the cell, causing no damage.

B) X-ray photons may collide with important cell chemicals and break them apart.

C) Ionization can cause critical damage to large molecules.

D) Irradiated cells cannot be repaired.

b

Which of the following statements regarding the biological effect mechanisms of the indirect effect is false?

A) Ionization dissociates water into hydrogen and hydroxyl radicals.

B) Ions have a strong tendency to seek out new combinations.

C) New chemicals, such as hydrogen peroxide, can form from hydrogen and hydroxyl radicals.

D) Radiation must be massive to destroy entire body tissues that result in death.

c

Which of the following is most sensitive to damage from radiation?

A) Bone cells

B) Epithelial cells

C) Lymphocytes

D) Muscle cells

a

Which of the following statements about radiation repair is false?

A) Somatic cells cannot repair radiation damage.

B) Scientists believe that some radiation effects are cumulative.

C) Ions have a strong tendency to recombine immediately to form water again.

D) The quantity, duration, and body area irradiated determine the amount of damage inflicted by the radiation.

a

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.

B) It predicts the effects of very low levels of radiation exposure.

C) It indicates that any amount of radiation has the potential to cause a biological response.

D) It has been adopted by the radiation protection community as the conservative approach to radiation exposure.

d

Each of the following is a potential effect of a low dose of radiation except one. Which one is the exception?

A) No cell response

B) Cell repairs itself and functions at preexposure levels

C) Cell repairs itself abnormally

D) Cell becomes radioactive

a

Which of the following statements regarding radiation injury is false?

A) The smaller the area of tissue exposure, the greater damage to the individual.

B) The greater the dose, the more severe the probable biological event.

C) The rate at which the radiation is absorbed may determine which biological effects occur.

D) A given dose may produce fewer biologic effects if the cells have a chance to recover.

b

Which of the following statements regarding radiation injury is false?

A) The amount of injury to an individual depends on the volume of tissue radiated.

B) The lethal dose (LD 50/30) for humans is 1.5 grays.

C) Younger, more rapidly dividing cells are more likely to incur damage.

D) Individuals vary in radiation sensitivity within the same species.

d

The lethal dose (LD 50/30) of radiation for humans is estimated to be

A) 4,500 grays.

B) 450 grays.

C) 45 grays.

D) 4.5 grays.

a

Which of these is not a symptom of acute radiation syndrome?

A) Constipation

B) Nausea

C) Hemorrhage

D) Hair loss

a

Which of the following is not a component of factors determining radiation injury?

A) Actively dividing cells with high mitotic activity are less sensitive.

B) Immature cells are more sensitive.

C) More specialized cells are more radioresistant.

D) Cells are most susceptible to injury during cell division.

b

Which of the following groups of cells are correctly ranked in order of radiosensitivity beginning with the most sensitive?

A) Muscle, brain, red blood, white blood

B) Reproductive, bone, nerve, muscle

C) Brain, bone, connective tissue, white blood

D) Red blood, bone, muscle, epithelial

c

Continued exposure to radiation over prolonged periods may result in each of the following except one. Which one is the exception?

A) May alter the ability of genetic cells to reproduce normally.

B) May affect the ability of genetic cells to repair damage.

C) May produce offspring with increased resistance to radiation exposure.

D) May result in cumulative chromosome damage.

a

What is the approximate surface (skin) dose of radiation from a full mouth series?

A) 12.6 mSv

B) 8 mSv

C) 0.4 mSv

D) 0.0005 mSv

b

Which of these periods immediately follows radiation exposure?

A) The period of injury

B) The latent period

C) The reparable damage period

D) The recovery period

b

When the severity of change is dependent on the radiation dose, the effect is called a(n)

A) stochastic effect.

B) deterministic effect.

C) acute radiation effect.

D) lethal dose effect.

d

At what dose of whole-body radiation would an observable short-term effect of acute radiation syndrome result?

A) 0.01 Gy

B) 0.25 Gy

C) 1.0 Gy

D) 1.5 Gy

c

Tissues have the capacity to repair radiation damage to a certain degree. However, some damage cannot be repaired and tissues remain weakened, especially with repeated exposures. This is called

A) a long-term effect.

B) radioresistant tissue.

C) a cumulative effect.

D) a stochastic effect.

c

What theory of radiation damage to cells results from free radicals combining to form toxins such as hydrogen peroxide?

A) Primary

B) Secondary

C) Indirect

D) Direct

b

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.

A) The first statement is true. The second statement is false.

B) The first statement is false. The second statement is true.

C) Both statements are true.

D) Both statements are false.

a

True or False? Scientists do not know whether low doses of radiation exposure carry health risks.

a. True

b. False

b

True or False? A less specialized cell is more radioresistant.

a. True

b. False

b

True or False? A nonthreshold dose-response curve indicates that there is a certain level of radiation below which no biological response should be anticipated.

a. True

b. False

a

True or False? The ALARA concept means "as low as reasonably achievable."

a. True

b. False

a

True or False? The effects of irradiation depend on the type of energy and duration of exposure.

a. True

b. False

b

True or False? All humans have the same sensitivity to radiation.

a. True

b. False

b

True or False? All cells in the human body have the same sensitivity to radiation.

a. True

b. False

a

True or False? X-rays have been shown to have cariogenic effects.

a. True

b. False

a

True or False? The structures of the oral and facial regions are relatively radioresistant.

a. True

b. False

a

True or False? Cells are most sensitive to radiation injury during mitosis (cell division).

a. True

b. False

a

True or False? The biological effects of very low levels are radiation cannot be predicted.

a. True

b. False

b

True or False? Radioresistant refers to those tissues that are protected by the lead apron and thyroid collar

a. True

b. False

b

True or False? The latent period refers to the time between exposure to radiation and the ionization of molecules.

a. True

b. False

b

True or False? When radiation affects any cells of the body except the reproductive cells, the effect is called "indirect."

a. True

b. False

a

True or False? A stochastic effect is when a biological response is based on the probability of occurrence rather than the severity of the change.

a. True

b. False

a

True or False? Cancer is a stochastic effect of exposure to radiation.

a. True

b. False

b

True or False? Erythema is a stochastic effect of exposure to radiation.

a. True

b. False

b

True or False? Because they do not divide and are very specialized, reproductive cells are radioresistant.

a. True

b. False

a

True or False? White blood cells (lymphocytes) and reproductive cells (oocytes) are more radioresistant because they do not divide and are very specialized.

a. True

b. False

a

True or False? The average effective dose equivalent from naturally occurring background radiation to the population of the United States is approximately 8 µSv (microsieverts) per day.

a. True

b. False