Radiation Biology

Question 1

Biological effects of radiation exposure can be classified as either ________ or _________.

Answer 1

Stochastic or deterministic

Question 2

A ___________ is one in which the probability of the effect occurring, (rather than its severity), increase with dose.

Answer 2

Stochastic effect

Radiation-induced cancer and hereditary effects are stochastic in nature.

Question 3

The probability of radiation induced-induced leukaemia is substantially greater after an exposure to 1 Gy than to 10 mGy, but here will he no difference in the severity of the disease if it occurs.

This is an example of what biological effect?

Answer 3

Stochastic effect

This are believed not to have a dose threshold, because damage to a few cells or even a single cell could theoretically result in production of the disease.

It is basic, but unproven, assumption that risk increases with dose and there is no threshold dose below which the magnitude of the risk goes to zero, that is the basis of modern radiation protection programs, the goal of which is to keep exposure as low as reasonably achievable.

Question 4

If a radiation exposure is very high, the predominant biologic effect is cell killing, which presents clinically as degenerative changes in the exposed tissue.

In this case, the effects are classified as ________ for which the severity of the injury (rather than its probability of occurrence), increase with dose.

Answer 4

Deterministic

Question 5

Deterministic effect (also referred to as tissue reactions) differ from stochastic effects in that they require much higher doses to produce a clinically observable effect and there is a _________ dose below which the effect does not occur or is sub clinical.

Answer 5

Threshold