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52 Cards in this Set
- Front
- Back
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A radiation monitor can be operated in which two modes?
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Pulse mode or current modes.
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Define pulse mode of a radiation detector?
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Each interaction is processed individually.
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Define a current mode of a radiation detector?
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each interaction is added together to form a net signal.
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What is the draw back to using a pulse mode radiation detector?
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Dead time.
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What is meant by a paralyzable system of a radiation detector?
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interactions that occur during dead time extend the dead time.
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What information is gathered from a current mode system?
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the dose rate.
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What is meant by efficiency of a radiation detector system?
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probability that it will detect a photon or a particle.
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In a gas filled detector which component is the anode?
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the wire (electrons move from this to the wall which is the cathode).
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What is meant by a geiger muller region of a counter?
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the amount of charge collected is the same regardless of the amount/type of energy deposited.
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Which type of radiation detector is used when an accurate measurement of exposure is required?
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Ionization chamber.
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A proportional counter must be filled with what?
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a gas with specific properties.
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In which mode is a Geiger Mueller counter usually used?
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Counts per minute.
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What type of detector with a GM meter allows beta particles to be detected?
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Pancake detector.
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T/F. Gm meters are used as dose rate meters.?
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False. |
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What type of radiation exposure device is measured with densitometer?
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film badge.
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Where should a film badge be worn during fluoroscopy?
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At the neck level.
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What type of radiation device uses lithium fluoride?
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Thermoluminesence dosimeter.
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What type of dosimeter allows an instantaneous reading of exposure?
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pocket dosimeter.
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What is the occupational dose limit for whole body exposure?
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50 mSv (5 Rem).
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What is the occupational dose limit for skin and extremity?
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500 mSv (50 Rem).
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What is the annual occupancy dose rate for the eye?
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150 mSv (15 Rem).
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What is the annual dose limit for the whole body for the public?
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1 mSv (0.1 Rem).
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What are the three main components of radiation safety?
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Time; distance ; shielding.
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Define the inverse square law?
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Exposure rate decreases according to 1 over the square of the distance from the source.
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Does the inverse square law apply to patients injected with radioactive material?
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No; it is only valid for point sources.
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To decrease exposure from patient scatter to the radiation worker what distance should they maintain?
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1 m and 90 degrees to the beam.
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By what percentage do lead aprons reduce scatter radiation?
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Greater than 90%.
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When designing the shielding for a radiographic room what does W represent?
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Number of xrays produced each week (mAs perweek).
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IN radiographic room shielding the fraction of time that radiation is directed at a barrier is which factor?
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Use factor (U).
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In radiographic room design what does occupancy factor (T) represent?
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the fraction of time that a person will spend in an adjacent area.
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How do you calculate the federal recommended lifetime exposure to a person (general public)?
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1 Rem x the persons age.
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What three types of radiation exposure need to be considered in in barrier design?
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primary; scattered; and leakage.
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What effect does beam filtration have on the primary beam?
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Increases the energy of the primary beam (reduces scatter).
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ALARA is an acronym for what?
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As Low As Reasonably Achievable.
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At what distance from the animal patient after injection of radioisotope is maximal exposure rate determined?
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1 m.
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What must the dose rate for an animal patient be before release of the patient from isolation?
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less than 100 mR for an indefinite period.
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The owner of an animal that has had a radionuclide administered must follow precautions for how many half lives?
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10.
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What is the half life of I-131?
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8 days.
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Release of an animal after I-131 can occur only when the surface dose rate has dropped to what?
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less than 50 mR/hr (avg 11 days).
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Once released the owner is told not to spend more than 10 minutes a day with the cat for how many days?
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15 days (surface exposure will be less than 2 mR/hr).
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How is internal exposure monitoring of personnel conducted?
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Bioassay.
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Define contamination?
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Uncontained radioactive material located where it is not wanted.
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What should you do if your skin is contaminated?
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Wash with soap and water.
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Areas with counts how many times greater than background radiation are considered to be contaminated?
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2 times.
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What is the maximum annual dose limit to the lens of the eye?
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150 mSv (15 Rem).
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What is the maximum annual dose limit to the skin or the extremity?
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500mSv (50 Rem).
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What Federal agency regulates nuclear material and source material and byproducts of nuclear fission?
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The NRC.
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What products does the NRC not regulate?
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Cyclotron produced materials.
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What is the function of the FDA in radiology?
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Regulates development and manufacturing and performance and safety of xray equipment.
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What federal agency regulates radiation safety and workplace exposure?
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The OSHA.
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What is an agreement state?
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It a state that has an agreement with the NRC to regulate their own radiation control programs.
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What federal agency regulates the radiation programs in non agreement states?
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the NRC.
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