Chapter 10
Radiation carcinogenesis



1. Which of the following statements is false?

a. Radiation damage can cause a cell to either die or continue being viable but mutated.

b. The two events above are very different when it comes to the dose dependence of their probability to occur and also when it comes to their impact on the organism to which the cell belongs.

c. Cell killing by radiation is said to be a "deterministic effect".

d. Cell mutating by radiation is said to be a "nonstochastic effect".



2. A deterministic effect:

a. has a threshold in dose but the severity of the effect is otherwise dose-independent.

b. has a threshold in dose and the severity of the effect increases with dose.

c. has no threshold in dose and the severity of the effect is a constant function of dose.

d. has no threshold in dose and the severity of the effect increases with dose.



3. Carcinogenesis and hereditary effects are:

a. deterministc effects.

b. stochastic effects.



4. Which of the following statements is false?

a. Stochastic effects have no threshold in dose.

b. The probability of induction of a stochastic effect increases with dose.

c. The severity of a stochastic effect increases with dose.

d. A cancer induced by 1 Gy is not worse than a cancer induced by 0.5 Gy.



5. Experiments with animals have shown that the cancer incidence probability increases with dose, reaches a maximum value and then decreases with dose. The decrease is due to the fact that:

a. higher doses than those corresponding to the incidence probability peak have no further effect on the tissue.

b. sublethal damage at high doses is repaired faster than sublethal damage at low doses.

c. increasing the dose beyond the value corresponding to the incidence probability peak results in increasingly larger amounts of cells that are killed by the radiation.



6. The latent period for leukemias is longer than for solid tumours.

a. True.

b. False.



7. Radiation-induced tumours appear:

a. at a fixed time interval following irradiation.

b. at random time intervals following irradiation.

c. late in life, i.e. at the same time as spontaneous tumours would.



8. The risk estimation model that calculates the excess incidence probability of cancer induced by radiation as a function of dose, the square of the dose, age at exposure, time since exposure and gender of the individual is called:

a. the absolute risk model.

b. the relative risk model.

c. the time-dependent relative risk model.

d. the time-independent relative risk model.



9. Quantitative risk estimates for radiation-induced cancer are mainly based on data from:

a. victims of radiation accidents.

b. experiments with animals.

c. the survivors of Hiroshima and Nagasaki.



10. The ratio of radiation-induced solid cancers to leukemias is (by the end of the lifespan of the irradiated population):

a. 2-4.

b. 4-6.

c. 6-8.



11. The number of radiation-induced malignancies:

a. is higher at low dose rates.

b. is lower at low dose rates.

c. is independent of the dose rate.



12. The lifetime risk of cancer lethality caused by radiation at high doses and high dose rates is:

a. 10% per Sv.

b. 20% per Sv.

c. 30% per Sv.



13. The lifetime risk of cancer lethality caused by radiation at low doses and low dose rates is:

a. 5% per Sv.

b. 10% per Sv.

c. 20% per Sv.



14. The enhancement in the risk of second malignancies associated to radiotherapy is found to be:

a. statistically uncertain.

b. small.

c. significant.