Week 3- Radiation Protection Standards

Natural Sources of Radiation

• Cosmic Radiation: from the sun and stars, 11%

• Terrestrial radiation: from naturally occurring elements in the earth’s crust 7%

• Radon: found underground, emits alpha radiation, results from decaying uranium 73%

  • Used in nuclear power plants

• Internal radiation: results from radioactive potassium-40 and carbon-14 inside our bodies 9%

Man Made Sources of Radiation

• Medical Sources: from diagnostic x-rays and nuclear medicine

  • Most significant source of man-made radiation

• Consumer Products: building materials, tv, fuels, lamps, tobacco, fallout from nuclear weapons testing

• Natural background radiation contributes ____mSv annual average

• The average person in the US receives ___mSv annually from medical examinations and consumer products

• Natural background radiation contributes 3.1mSv annual average

• The average person in the US receives 3.0mSv annually from medical examinations and consumer products

Equivalent dose vs BERT

• Equivalent dose: used to estimate risk in humans

• BERT: expresses radiation dose from background radiation

• The ratio of heat to X-rays produced in an X-ray tube is ____

• FMX with rectangular PID has an effective dose of _____mSv and BERT days = _____

• Panoramic x-rays have an effective dose of _____mSv and BERT days = _____

• CTs have an effective dose of _____mSv and BERT days = _____

• The ratio of heat to X-rays produced in an X-ray tube is 99:1

• FMX with rectangular PID has an effective dose of 35mSv and BERT days = 4

• Panoramic x-rays have an effective dose of 9-26mSv and BERT days = 1-3

• CTs have an effective dose of 2000mSv and BERT days = 243

Standard Radiation Protection

Environmental Protection Agency (EPA): Charged with protecting human health and the environment

Nuclear Regulatory Commission (NRC): regulates nuclear plants, research reactors, medical, industrial and academic licensees to use and store radioactive materials

Food and Drug Administration (FDA): regulates food, tobacco, supplements, vaccines, biopharmaceuticals, medical devices, electromagnetic radiation-emitting devices, veterinary products and cosmetics.

OSHA: safety of workers exposed to radiation

National Council on Radiological Protection and Measurements (NCRP): information, guidance and recommendations on radiation protection

ADA: recommends dentists on safe radiation protection

• What is the max permitted annual dose of ionizing radiation for healthcare workers?

• What is the monthly permissible dose for a pregnant operator? what is does the acronym ALARA mean

• 50mSv

• 0.5mSv, as low as reasonably possible dosage for pregnant women

Protection Principles during Radiation Procedures

• Time: reduce exposure as much as possible

• Distance: operator should be behind barrier or 6 feet away and a 90 or 135 degree angle to minimize exposure (4 feet for panoramic)

• Shielding: barriers of lead, concrete or water protect from penetrating radiation

Operator Protection

• The operator may not hold the receptor for the patient during exposure

• The operator may not hold the tube or cone or patient during exposure

• Stay behind protective barrier

• Dentistry is exempt from monitoring in Florida

Controlled vs Uncontrolled Area

• Controlled: a limited-access area in which the occupational exposure of personnel to radiation is under the supervision of an individual in charge of radiation protection

• Uncontrolled: does not meet the above criteria

• What does filtration do on the tube beam?

• Dental imaging reduces radiation exposure by approximately __% when compared to D-speed film and __% when compared to E-speed film

• Decreases low-energy photons absorbed by soft tissue

• Dental imaging reduces radiation exposure by approximately 90% when compared to D-speed film and 60% when compared to E-speed film

• When do you use thyroid shield and when do you not use it?

• What is the function of the lead aprons and shields?

• You use it on intraoral radiographs unless its for a panoramic

• To protect the thyroid and gonads

Define the Principle of justification, Principle of optimization and Dose limitation

• Principle of Justification: radiation exposure should do more good than harm

• Principle of Optimization: all exposures are ALARA

• Dose Limitation: have limits for workers and public