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Radiobiology chpt 36
radiobiology chpt 36
| Question | Answer |
|---|---|
| what are late effects of radiation based on | low doses delivered over long periods of time |
| what are radiation protection guidelines based on | late effects of radiation |
| how must epidemiologic studies be conducted to study effects of low dose radiation | with millions of people |
| 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 | lymphatic |
| how long can effects be delayed in peripheral lymphocytes | 20 years |
| what responses are damage to circulating lymphocytes | early or late |
| low doses of radiation have been proven to cause what? | chromosome damage |
| what can be caused as a late effect of irradiation of blood forming organs | leukemia |
| what is used principally to produce radionuclides for usen in nuclear medicine | cyclotron |
| where are the largest particle accelerators in the world located | Argonne Nat'l Laboratory (USA) and CERN (Switzerland) |
| What type of problem did early cyclotron physicist have and why | cataracts due to looking directly into beam and high exposure |
| where do cataracts occur | posterior pole of the eye lens |
| what type of dose response are cataracts | non linear threshold (200 rads) |
| what type of CT machine is it common to modify exam to reduce eye dose | 2D ( not needed for 3D) |
| What is the life shortening span for every rad | 10 days ( worst case) |
| what is the life shortening span for radiation workers | 12 days (worst case) |
| formula for relative risk | observed cases/expected cases |
| what is the theory of radiation hormesis | that very small doses of radiation are good for us (below 10 rads) |
| 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 |
| When can absolute risk be calculated | when 2 dose levels are known |
| who/what determines the absolute risk of radiation-induced malignant disease | NAS-BEIR |
| What is the value of absolute risk | 5x10^-4rem^-1 |
| what type of responses are all radiation induced malignancy | stochastic |
| what is stochastic | no threshold even the smallest dose can cause an effect |
| how have radiation induced malignancy been observed | experimental animals (at human level they have been observed but insufficiet data) |
| what type of dose respone is leukemia | linear and non threshold |
| what groups have exhibited an elevated incidence of leukemia after radiation exposure | atomic bomb survivors, American radiologists, radiotherapy pt, and children irradiated in utero |
| where have we accumulated the most info for radiation induced leukemia | Atomic bomb survivors (Hiroshima and Nagasaki) |
| How much greater was the leukemia incidences for Hiroshima and Nagasaki survivors | 100 times |
| 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 |
| What were pt with ankylosing spondylitis treated with and what problems did it cause | radiation helped pt to walk and function better but it was not known that it caused leukemia |
| why is it impossible to link cancer to radiation | because it occurs in high proportions of the population |
| what is known to cause thyroid cancer | doses of radiation to the thymus as children |
| what occupation was known to cause bone cancer | watch dial painters |
| what occupation was known to cause lung cancer | German miners exposed to radon |
| Skin cancer has what type of dose response | threshold |
| what caused liver cancer | thorotrast used for angiography between 1925 and 1945 |
| how many additional deaths are predicted to occur because of Three Mile Island | 2 |
| What is the BEIR | Biological effects of Ionizing Radiation |
| What effect does chronic low doses have on fertility | none |
| what is the most radiosensitive period in pregnancy | 1st trimster |
| what period is of the least concern in pregnancy | first 2 weeks ( response is all or nothing) |
| what is the risk of childhood leukemia after exposure in utero | 1.5 |
| Why do we know the genetic effects on humans | mice and fruit fly studies |
| what is doubling dose | dose that produces twice the genetic mutations than with non irradiation |
| what are the abnormalities associated with radiation in utero | mental retardation and microcephaly (small head) |
| cancer is what type of effect of radiation exposure | late |
| what is the risk for skin cancer | 4:1 |
| what is the latent period for skin cancer | 5 to 10 years |
Created by:
subee61
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