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104 Cards in this Set
- Front
- Back
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What is the binding energy of silver K-shell
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25 keV
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What are film badge filters made of?
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Cu, Sn, Al, plastic
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What is the minimum air kerma film badges can detect?
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0.2 mGy
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How is the energy released in thermoluminescent dosimeters?
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Application of heat
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What is the light output of the TLD proportional to?
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air kerma
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What is the material of TLD used in radiology?
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LiF
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Why is lithium fluoride used as the TLD in soft tissues?
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Because it is a tissue equivalent (Z = 8.3 with soft tissue Z=7.7)
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What parameter does film dosimetry depend on that TLD's do not?
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photon energy
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What is the detection limit used to monitor workers in radiology?
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0.2 mGy
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What is the typical x-ray tube output in air kerma at a distance of 1 m (80 kV)?
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0.1 mGy/mAs
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Are ionization chambers sensitive?
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No
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What are added to Geiger counters to improve stability?
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Quenching gases
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How many photons are in a typical x-ray beam?
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10^7/mm2
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What are analog dosimeters made of?
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Positively charged quartz fiber suspended in an air-filled chamber
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What is the typical range of a pocket ionization chamber?
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0 to 2 mGy
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What is ICRP?
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International Commision on Radiological Protection
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What ICRP publication provides recommendations for radiation workers?
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Publication 103
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What is ICRU?
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International Commision on Radiological Units and Measurements
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Which commission replaced exposure with air kerma?
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ICRU
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What is the radiation protection body in the US?
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National Council on Radiation Protection and Measuremetns (NCRP)
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Which parts of the CFR are the NRC rules promulgated?
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Parts 19 and 20, Chapter 10
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What body meets annually to coordinate x-ray protection activities?
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Conference on Radiation Control Program Directors (CRCPD)
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What effective dose limit is recommended by the ICRP, averaged over 5 years?
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20 mSv per year, over 5 years
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What is the lifetime cumulative effective dose limit recommended by the NCRP?
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ten times the individual's age (mSv)
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what is the regulatory effective dose limit in the US?
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50 mSv/year
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What is the main difference in regulation protection between state and federal levels?
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Federal regulates nuclear material, states regulate x-ray devices
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Even the most highly exposed workers are unlikely to receive doses over what level?
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5 mSv
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Above what dose level should acute and long-term risks need to be addressed during an emergency exposure?
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500 mSv
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What is the ICRP recommended limit for members of the public per year?
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1 mSv/year
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What is the US regulatory limit for public members per year?
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1 mSv/year
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Are natural background radiation and medical doses included when determining doses for members of the public?
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No
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What is the ICRP limit for a worker from declaration of pregnancy to birth?
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1 mSv, the ICRP considers the fetus a member of the public
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What is the NCRP recommended monthly radiation limit to the embryo or fetus?
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0.5 mSv
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What is the US monthly regulatory limit for fetus and the total dose limit?
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0.5 mSv/month, 5 mSv total, (whcih is higher than the public dose)
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Pregnant women wear a dosimeter where?
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Abdomen
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The dose of the fetus is taken to be what fraction of the skin dose?
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Half
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What is the dose limit to the eye lens per year?
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150 mSv
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What is the dose limit to the skin?
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500 mSv/year
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Where are skin doses calculated?
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Over the most highly exposed 1 cm2
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What is the dose limit for hands and feet of radiation workers?
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500 mSv/year
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What are the dose limits to the public for the eye lens and skin?
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15 mSv/year for the eye
50 mSv/year for the skin (ten times less than radiation workers) |
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The scatter dose level from patients at 1 m is what percent of the entrance skin dose?
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~0.1%
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What is the scatter radiation exposure for PA chest x-ray at 1 m?
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0.1 uGy
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What is the scatter radiation exposure for lateral skull x-ray at 1m?
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1.5 uGy
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What is the scatter radiation exposure for AP abdomen x-ray at 1m?
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3 uGy
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What is the scatter radiation exposure for CT scan at 1m?
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30 uGy
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What is the scatter radiation exposure for fluoroscopy (1min) at 1m?
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20 uGy
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What is the regulatory limit for leakages radiation at 1 m?
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<1 mGy/hour
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What is the half value layer of lead at 130 kV?
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0.3 mm
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How much lead should lead aprons have in diagnostic radiology?
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0.25 mm to 0.5 mm
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How much does a lead apron with 0.5 mm weigh?
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5 kg
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What is the use factor?
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Fraction of time that radiation points at a specific barrier.
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What is the occupancy factor?
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Fraction of time that people work on the other side of the barrier?
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What is the use factor (U) for each of these: floor, walls, and ceiling?
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Floor 1
Walls 1/16 Ceiling 0 |
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What is the occupancy factor (T) for each of these: labs and offices, restrooms, and corridors and lounges?
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Offices and labs 1
Corridors and lounges 1/5 Restrooms 1/20 |
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What is the typical shielding for most x-ray installations?
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1.6 mm
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What are typical doses for radiologists and technologists that work inside x-ray rooms?
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5 mSv
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How far should operators stand for portable examinations?
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2m
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What is the lead equivalence of gloves?
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0.25 mm
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What is the entrance skin dose for a PA radiograph?
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0.2 mGy
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What is the skin dose for lateral x-ray?
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0.5 mGy
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What is the effective dose for a CXR?
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0.05 mSV
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What is the effective dose for a skull radiograph?
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0.1 mSv
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What is the effective dose for an abdominal radiograph?
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0.5 mSv
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What is the range of air kerma for fluoroscopy?
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10 to 100 mGy/minute
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What is the typical air kerma rate for normal size adults in fluoroscopy?
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30 mGy/minute
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Patient doses can be reduced by up to 50% using what mode in fluoroscpy?
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Pulsed mode
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What is the maximum air kerma rate in high dose mode in fluroscopy?
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200 mGy/minute
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What thickness and percent glandulatrity does the ACR phantom simulate in mammography?
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4.2 cm breast with 50% glandularity?
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What is the average glandular dose in screen-film mammography?
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1.8 mGy per image
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What is the AGD in digital mammography?
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1.5 mGy per image
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What is the effective dose in barium swallow studies?
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1 to 2 mSv
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What is the effective dose in barium meal images?
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2 and 8 mSv
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What is the effective dose of barium enemas?
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5 and 15 mSv
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What is the effective dose for a cardiac catheterization?
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7 mSv
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Cerebral angiography has effective doses that range from what?
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1 to 10 mSv
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What is the typical effective dose in abdominal angiography?
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20 mSv
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What is the dose in head CT exam? (is this equivalent or effective dose)
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50 mGy
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What is the dose of body CT exam? (is this equivalent or effective dose)
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25 mGy
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What is the embryo/feus dose if it is directly exposed?
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25 mGy per phase
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Head CT in infants and young children can be up to how many times higher than for adults when using the same technique?
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4 times
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Below what level can deterministic effects be minimized?
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2 Gy
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What is the fatal cancer risk for a lose dose (0.2 mSv effective dose) radiographic examination?
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1 in 100,000
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Whta is the fatal cancer risk for effective dose of 20 mSv radiographic exam?
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1 in 1000
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What model is used to extrapolate radiation risks from high to low doses?
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Linear no threshold model
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What is the breast cancer risk for a 4 mGy breast dose in mammography?
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8 in 1 million
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How much should x-ray beam intensity (mAs) be reduced in a 1 year old and newborn for a head CT?
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15% and 25%
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What is the dose delivered by cosmic rays?
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0.3 mSv/year
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What is the dose of a transcontinental flight?
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0.03 mSv
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How much additional dose do air crews receive per year?
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5 mSv
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How much dose does space travel result in?
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0.01 mSv/hour
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How much dose does soil radiation result in per year?
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0.3mSv/year
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What is the yearly dose of cosmic rays, terrestial radioactivity, and primordial nucleotides per year?
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1 mSv
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What internal nucleides have been around since the birth of our planet?
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K-40 and C-14
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What gives the biggest conribution to natural background radiation?
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Radon-222
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What is the parent compound of radon and where does it come from?
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Radium-226, from uranium in soil
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How does radon decay, and what is its half life?
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Alpha emitter, 4 days
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What cancer is radon associated with?
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Bronchogenic cancer
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What is the average concentration of radon outdoors?
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4 to 8 Bq/m3
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What is the average concentration of radon indoors?
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40 Bq/m3
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What is the annual effective does from radon?
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2 mSv / year
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At what level of radon is remedial action required?
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160 Bq/m3
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What is the US population average dose from diagnostic medical exams?
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3.2 mSv
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What modality is responsible for more than half of the population dose from diagnostic imaging?
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CT
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