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  • Section 6 Radiation-Induced Injury to the Gonads Answers and Feedback

  • Section 6 Radiation-Induced Injury to the Gonads Answers and Feedback 

    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 is False. 

    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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