X-Ray Certification Radiobiology 2

Question 1

What process decomposes water molecules through radiation exposure, producing free radicals that can damage DNA?

Accepted Answer

Radiolysis

Answer

Radiolysis is the decomposition of water molecules by radiation, producing hydroxyl radicals (OH•) and hydrogen radicals that attack DNA indirectly.

Question 2

Approximately what percentage of radiation-induced biological damage occurs through indirect action via water radiolysis?

Accepted Answer

70–80%

Answer

Approximately 70–80% of radiation-induced biological damage in humans occurs through indirect action, where free radicals from water radiolysis attack DNA.

Question 3

What does the oxygen enhancement ratio (OER) measure in radiation biology?

Accepted Answer

Ratio of dose needed to produce the same effect in hypoxic vs. oxygenated cells

Answer

The OER is the ratio of radiation dose required to produce the same biological effect in hypoxic (oxygen-deprived) versus well-oxygenated cells, typically 2.5–3.0 for x-rays.

Question 4

Which type of radiation effect is characterized by a threshold dose, below which no observable effect occurs?

Accepted Answer

Deterministic effects

Answer

Deterministic effects such as cataracts and erythema have a threshold dose; below that level, cellular repair prevents any observable tissue effect.

Question 5

Acute radiation syndrome (ARS) is best described as:

Accepted Answer

A collection of symptoms following high whole-body dose received in a short time

Answer

ARS encompasses hematopoietic, gastrointestinal, and central nervous system syndromes that occur after a large dose of whole-body radiation delivered over a short period.

X-Ray Certification Practice Test

X-Ray Certification Practice Test

X-Ray Certification Radiobiology 2