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Chapter 36 Bushong
Late Effects of Radiation
Question | Answer |
---|---|
what are late effects of radiation based on? | stochastic effects |
what are radiation protection guidelines based on? | Late effects of radiation and on linear, nonthresh dose-response relationships |
how must epidemiologic studies be conducted to study effects of low dose radiation? | Studies of large number of people exposed to a toxic substnace |
what effect was was caused by high doses in the early practices of radiology that caused callused, cracked and discolored skin on hands and forearms of radiologists? | radiodermatitis |
what type of stem cells are damaged by radiation? | lymphocytic stem cells |
how long can effects be delayed in peripheral lymphocytes? | for as long as 20 years |
what responses are damage to circulating lymphocytes early or late? | chromosome damage |
low doses of radiation have been proven to cause what? | chromosome aberations that may not be apparent until many years after radiation exposure |
what can be caused as a late effect of irradiation of blood forming organs? | hematologic depression as an early response or leukemia as a late response |
what is used principally to produce radionuclides for used in nuclear medicine? | modern cyclotrons |
what type of dose response are cataracts? | nonlinear, threshold (stochastic) |
What is the life shortening span for every rad? | at worst, humans can expect a reduced life span of approximately 10 days for every rad |
what is the life shortening span for radiation workers? | life is shortened by only 12 days |
formula for relative risk observed cases/expected cases? | relative risk = observed cases/expected cases |
what is the theory of radiation hormesis? | suggests that very low radiations doses are beneficial |
What is the only theory we practice? | ALARA |
relative risk factor of 1 indicates what? | no risk at all |
relative risk factor of 1.5 indicates what? | frequency of late response is 50% higher in the irradiated population? |
who/what determines the absolute risk of radiation-induced malignant disease? | National Academy of Science (NAS) and Committee on the biological Effects of Ionizing Radiation (BEIR) |
what is stochastic? | one that has no dose threshold |
what type of responses are all radiation induced malignancy? | all the late effects |
how have radiation induced malignancy been observed? | experimental animals and at the human level late effects have been observed |
what type of dose response is leukemia? | linear and nonthreshold (stochastic) |
what groups have exhibited an elevated incidence of leukemia after radiation exposure? | atomic bomb survivors |
where have we accumulated the most info for radiation induced leukemia? | observations of survivors of the atomic bombings of Hiroshima and Nagasaki |
How much greater was the leukemia incidences for Hiroshima and Nagasaki survivors? | 100 times that in the nonirridiated population |
what is the latent period for radiation induced leukemia? | 4 to 7 years |
what is the risk period for radiation induced leukemia? | 20 years |
What year was the incidence of leukemia high in radiologist and why? | 1940; no protection and received doses over 100 rad per year |
Skin cancer has what type of dose response? | threshold |
What is the BEIR? | Biological Effects of Ionizing Radiation |
What effect does chronic low doses have on fertility? | low-dose, chronic irridiation does not impair fertility |
the most radiosensitive period in pregnancy? | during the first trimester |
what period is of the least concern in pregnancy? | first 2 weeks |
cancer is what type of effect of radiation exposure? | late effect |
what is the risk for skin cancer? | 500 to 2000 rad risk 4:1 ; 4000 to 6000 rad or 6000 to 10000 rad risk 14:1 and 27:1 respectively |
what is the latent period for skin cancer? | approximately 5 to 10 years |