Week 8 B Chapter 37 Radiation and Chapter 38 Radioliology 78

Week 8 B Chapter 37 Radiation and Chapter 38 Radioliology 78

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Unformatted text preview: Chapter 37 Radiation and Pregnancy and Genetic Effects From the first medical application of x-rays, there has been a concern and apprehension regarding the effects of radiation before, during and after pregnancy. Before pregnancy- concerns about fertility During pregnancy- possible congenital effects After pregnancy genetic effects All have been observed in animals and humans. Effects on Fertility The early effects of high level radiation exposure on fertility is known in both men and women. Doses as low as 10 rad may delay or suppress menstruation in women and reduce the number of spermatozoa. Doses of 200 rad can produce temporary infertility. Dose of 500 rad will produce sterility. Effects on Fertility The short term effects are documented and known to be dose related. The effects of low-dose, long term irradiation on fertility is less well defined. Animal results are lacking. Those that exist demonstrate no effect in exposure of 100 rad per year. A study of 150,000 rad techs found no effect on fertility over a 12 year sampling period. Low-dose, chronic irradiation does not impair fertility. Irradiation in Utero Irradiation in utero concerns two types of exposures. Those to the radiation worker Those to the patient There is substantial data about animal exposure to relatively high doses of radiation delivered during the various periods of gestation. Irradiation in Utero The embryo is a rapidly developing cell system so it is very sensitive to radiation. With age, the radiosensitivity decreases and the pattern continues into adulthood. The effects of exposure in utero are time and dose related. LD50/60 of mice After maturity, radiosensitivity increases with age. It begins to decrease with age at the end of child bearing age. The study shows mice age in weeks and human age in years. Effects of 200 Rad Delivered at Various Times in Utero Exposure During the 1 st Trimester All observations point to the first trimester of pregnancy as the most radiosensitive period. With in the first two weeks after fertilization to most pronounced effect of a high radiation dose is fetal death which is manifested as a spontaneous abortion. Observed in radiation therapy patients but only after very high exposures. The 1 st 2 weeks of pregnancy may be of least concern because the response is all or nothing. Exposure During the 1 st Trimester From animal data, it would appear that this response is very rare. The best estimate is a 10 rad exposure during the first two weeks would induce 0.1% rate of spontaneous abortion. This is added to the 25% to 50% normal incidence of spontaneous abortion....
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Week 8 B Chapter 37 Radiation and Chapter 38 Radioliology 78

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