Section 6 Radiation-Induced Injury to the Gonads Answers and
1. ANSWER: A-TRUE, B-TRUE, C-FALSE, D-TRUE, E-FALSE
FEEDBACK: Temporary sterility in males occurs after a dose as low as 0.15Gy. Option A is True. Permanent
sterility in females occurs at doses of 3.5Gy or more. Option B is True. Radiation-induced sterility in males does
not affect hormone levels or libido. Option
C is False. Radiation-induced sterility in females results in symptoms
similar to those in normal menopause. Option
D is True. Because the cells in the male reproductive system involve a
hierarchy of cells in a self-renewal system, there is a latent period between
irradiation and sterility. Option E
2. ANSWER: A-FALSE, B-FALSE, C-TRUE, D-FALSE, E-TRUE
FEEDBACK: Mutations produced by radiation are indistinguishable from those that
occur spontaneously. Option A is False.
There is no statistically significant excess of hereditary effects in the
children of the Japanese exposed to radiation by the atomic bombs, which
indicates that humans are certainly not more sensitive than mice and might be
less sensitive. Option B is False.
Risk estimates for hereditary effects are based on the “Megamouse” project. Option C is True. If 1 Gy (or 1
Sv) is required to increase the mutation rate by 100%, then 0.1–0.2 Gy (or Sv)
would be required to increase the mutation rate by 10%–20%. However, the
average background radiation in the United States is only 3 mSv (i.e., 0.003
Sv). Option D is False. The
doubling dose is the dose required to double the natural or spontaneous level
of mutations. The BEIR committee quoted a range, 0.5–2.5 Sv, while UNSCEAR
quoted a single figure, 1 Gy. Option
E is True.
3. ANSWER: A-TRUE, B-TRUE, C-TRUE, D-FALSE
FEEDBACK: The genetically significant dose (GSD) is the dose that if given to everyone
in the U.S. population would result in the same number of mutations as would
the actual variable dose received by part of the population during medical
irradiation. Therefore, the GSD due to medical radiations depends on the gonad
doses, the age and sex of the patients, and the number of persons exposed. Options A, B, and C are True.
The time of day is obviously irrelevant. Option
D is False.
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