Flashcards in Ionising radiation 2 Deck (20):
what is the LNT model ?
linear no threshold model
- this refers to stochastic effects of ionising radiation
- there is no safe limit of exposure
- however this has been questioned due to the effects at chernobyl
what are the prodromal effects caused by exposure to ionising radiation ?
anorexia, nausea, vomitting and diarrhoea
these can last hours
these effects occur due to acute cell death
what occurs after the prodromal phase ?
latent phase- this lasts several days
- it depends on dose of radiation
after the latent phase, overt illness occurs. what happens?
stop producing red blood cells so there is not enough circulating oxygen,
- start to haemorrhage due to platelets not being produced, vunerbale to infections due to WBCs
after this it is either recovery or death
what level of exposure to ionising radiation has no one ever survived from even with treatment ?
greater than or equal to 100 Gys
what biological effects occur between 1-10 Gy dose of radiation ?
haematological death - cells in bone marrow are most sensitive to ionising radiation
what biological effects occur between 10-60 Gy dose of radiation ?
- epithelial cells are also sensitive - they have a high turnover rate in GIT
what biological effects occur at 100Gy dose of radiation ?
what does LD50/30= 2.5-4.5Gy mean ?
without medical care doses of 2.5 to 4.5 Gy would be lethal after 30 days in 50% of patients
what are the acute effects of radiation exposure on the skin ?
low level= erythema, temporary hair loss
high level= inflammation, desquamation (loss of skin), ulceration, permanent hair loss, cancer
what are the acute effects of radiation exposure to the eyes ?
cell death in the lens leads to radiation-induced cataracts
what are the acute effects of radiation exposure to the gonads ?
low level= temporary sterility in males and females
high level= permanent sterility in males and females
what does cytogenetic effects mean ?
exposure to radiation can cause chromosomal damage
to treat cancer, 20-80Gy is used which is significant greater than the LD50/30 but why does this not cause death ?
because doses are given separately to allow the body to recover and they are only given to a specific area of the body
what are the long term effects of exposure to ionising radiation ?
cancers- most frequent are breast, thyroid( particularly for radon because it is readily taken up by the thyroid), lung, leukemias and alimentary tract
what are the long term effects of ionising radiation on the foetus ?
prenatal or neonatal deaths
what do the effects of ionising radiation on the foetus depend on ?
dependent upon time of exposure
- 3-8 weeks cataracts
- whole gestation for childhood leukemias
- 4-19 weeks for mental retardation
- 4-18 weeks- microencephaly
-4-8 weeks- microphthalmia
- 4-19 weeks growth retardation
4-8 weeks skeletal defects
where is the highest risk of exposure to radon gas ?
in areas with lots of granite rock
- contributes to about 50% of normal radiation we are exposed to
how does radon gas cause damage ?
it can enter and accumulate in buildings and sources including soil, rock and building materials and water supplies
- it can be readily inhaled and it contains alpha particles so it is not dangerous to us externally but once its inhaled it is very dangerous