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sthomp88
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What type of radiation are humans exposed to on a daily basis?
background radiation
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a form of ionizing radiation that is ubiquitous in the environment
background radiation
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What are 2 types of naturally occuring background radiation?
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radiation that originates from the stars and the sun
cosmic
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a person's exposure to cosmic radiationdepends on________
altitude
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the higher the altitude, the__________the exposure to cosmic radiation
greater
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radiation that occurs naturally and is emitted from radioactive material present in the earth and air
terrestrial radiation
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whatare 2 examples of terrestrial radiation?
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The average dose of background radiaton received by an individual in the U.S. ranges from ________to________mrads per year
150-300 (0.0015-0.003 Gy per year)
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true or false. background radiation exposure may vary according to geographic location
true
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geographic areas that contain more radioactive materials are associate with increased amounts of__________
terrestrial radiation
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geographic areas at higher elevations are associated with increased amounts of________radiation
cosmic radiation
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What is the single largest contributer to artficial radiation exposure?
medical radiation
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What are 5 examples of medical radiation?
- medical radiographic procedures
- dental radiography
- fluoroscopy
- nuclear medicine
- radiation therapy
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What type of radiation exposure equals the average yearly dose from all other exposures combined, and typically accounts for half of the total exposure recieved?
medical radiation
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the likelihood of adverse effects or death resulting from exposure to a hazard
risk
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in dental radiograph, risk is the likelihood of an adverse affect, specifically ______ _______, occurring from exposure to ionizing radiation
cancer induction
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What is the estimated potential risk of dental radiography inducing fatal cancer in an idividual?
3 in 1,000,000
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What is the riskof a person developing cancer spontaneoulsy?
3300 in 1,000,000 (much higher than from dental radiography)
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true or false. risks from dental radiography are not significantly greater than the risks of other everyday activities in life
true
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What is the dose required to produce cancer in the thyroid gland?
6000 mrad (0.06 Gy)
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What are the 4 critical organs in dental radiographic procedures?
- thyroid gland
- bone marrow
- skin
- eyes
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What is the average dose to the thyroid gland with rectangular collimation, d-speed film, long PID, 20-film series)
- 6 mrads
- 0.00006 Gy
- 1/1000 of the dose necessary to induce thyroid cancer
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What areas account for a small percentage of active bone marrow in dental radiography?
areas of maxilla and mandible
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The risk of cancer induction (leukemia) is dirctly associated with the amound of blood-producing tissues_________ and the_________
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What dose is leukemia usually induced at?
5000 mrad (0.05 Gy)
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What is the average bone marrow dose from PA radiography?
- 1-3 mrads
- 0.00001-0.00003 Gy
- between 2000 and 5000 films would have to be exposed to induce leukemia
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What dose is required tocause erythema?
- 250 rads
- 2.5 Gy
- in a 14 day period
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How many films would have to be taken in a 14 day period to cause erythema?
500
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How many mrads are necessar to induce cataract formation?
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What is the average surface dose to the cornea of the eye in dental radiography?
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What are 4 factors of patient protection that exposure depends on?
- film speed
- collimation
- technique
- exposure factors
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a longer source to film distance will_____ radiation exposure
limit
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