Late Effects Of Radiation Flashcards
T/F
No conclusive proof exists that low level ionizing radiation doses below 0.1Sv cause significant increase in the risk of malignancy
True
Somatic
Body
T/F
Non somatic could lead to a genetic mutation
True
Have a threshold and their severity depends on dose
Ex. Tissue reactions, cataracts
-results as slow development of change, could be altered with medical intervention
Non stochastic
Probability depends on the dose received but the severity is not affected
Ex. Cancer
Stochastic
-cataract formation
-fibrosis
-organ atrophy
-loss of parenchymal cells
-reduced fertility
-sterility
Late deterministic
(Non stochastic) effects
Effects of radiation on the embryo fetus in utero that depend on the fetal stage of development and the radiation dose received
Teratogenic effects
-cancer
-genetic/hereditary effects
Late probabilistic (stochastic) effecgs
Forecasts that a specific number of malignancies will occur as a result of exposure
Absolute risk model
(Slide 9 image)
Predicts that the number of excess cancers will increase as the natural incidences of cancer increases with advancing age in a population
Relative risk model
(Slide 9 image)
What are some examples of major types of late effects?
-carcinogenesis
-cataractogenesis
-embryologic effects (birth defects)
-the formation of cancer
-LATE PROBABILISTIC/STOCHASTIC effect
-random occurrence
-non threshold
-severity is not dose related
Carcinogenesis
T/F
Ionizing radiation can cause damage that does not manifest itself for years or even decades
True
Ex.
-leukemia
-skin carcinoma
-thyroid
-lung
-breast
-osteosarcoma
*radiation induced cancer is not different than naturally occurring cancer
T/F
Leukemia is one of the most frequently observed radiation induced cancers
-responsible for 1/6 of the fatalities from radio carcinogenesis
-can be acute or chronic (lymphoid or myeloid)
Leukemia
What relationship does leukemia have?
Linear non threshold
-latent period of 4-7 years with an at risk period of 15-20 years
T/F
The age of the person at the time of irradiation influences the risk of leukemia
True
As age increases, incidence decreases
What relationship does thyroid cancer have?
Linear non-threshold
T/F
Females have a 3-5x greater risk of thyroid cancer than males because of hormonal influences
True
What relationship does breast cancer have?
Linear non-threshold
-the incidence of breast cancer rises with radiation dose
-relative risk for breast cancer ranging from 4:1 to as 10:1
T/F
Mammography was once shown to potentially cause breast cancer, but with advancements in dose reduction, recent studies have shown no evidence of increased risk
True
What bones are most affected by osteosarcoma?
Pelvis
Femur
Mandible
What dose causes osteosarcoma?
Doses >5Gy
What relationship do cataracts have?
Non-stochastic/deterministic
Non-linear threshold
What dose is considered to cause cataracts?
High probability of developing cataracts after a single dose of 2Gy
As low as 0.5Gy
