What type of radiation are humans exposed to on a daily basis?
background radiation
a form of ionizing radiation that is ubiquitous in the environment
background radiation
What are 2 types of naturally occuring background radiation?
cosmic
terrestrial
radiation that originates from the stars and the sun
cosmic
a person's exposure to cosmic radiationdepends on________
altitude
the higher the altitude, the__________the exposure to cosmic radiation
greater
radiation that occurs naturally and is emitted from radioactive material present in the earth and air
terrestrial radiation
whatare 2 examples of terrestrial radiation?
potassium - 40
uranium
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)
true or false. background radiation exposure may vary according to geographic location
true
geographic areas that contain more radioactive materials are associate with increased amounts of__________
terrestrial radiation
geographic areas at higher elevations are associated with increased amounts of________radiation
cosmic radiation
What is the single largest contributer to artficial radiation exposure?
medical radiation
What are 5 examples of medical radiation?
medical radiographic procedures
dental radiography
fluoroscopy
nuclear medicine
radiation therapy
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
the likelihood of adverse effects or death resulting from exposure to a hazard
risk
in dental radiograph, risk is the likelihood of an adverse affect, specifically ______ _______, occurring from exposure to ionizing radiation
cancer induction
What is the estimated potential risk of dental radiography inducing fatal cancer in an idividual?
3 in 1,000,000
What is the riskof a person developing cancer spontaneoulsy?
3300 in 1,000,000 (much higher than from dental radiography)
true or false. risks from dental radiography are not significantly greater than the risks of other everyday activities in life
true
What is the dose required to produce cancer in the thyroid gland?
6000 mrad (0.06 Gy)
What are the 4 critical organs in dental radiographic procedures?
thyroid gland
bone marrow
skin
eyes
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
What areas account for a small percentage of active bone marrow in dental radiography?
areas of maxilla and mandible
The risk of cancer induction (leukemia) is dirctly associated with the amound of blood-producing tissues_________ and the_________
irradiated
dose
What dose is leukemia usually induced at?
5000 mrad (0.05 Gy)
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
What dose is required tocause erythema?
250 rads
2.5 Gy
in a 14 day period
How many films would have to be taken in a 14 day period to cause erythema?
500
How many mrads are necessar to induce cataract formation?
200,000 mrads
2 Gy
What is the average surface dose to the cornea of the eye in dental radiography?
60 mrads
0.0006 Gy
What are 4 factors of patient protection that exposure depends on?
film speed
collimation
technique
exposure factors
a longer source to film distance will_____ radiation exposure
