Filtration and stuff
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Filtration and stuff
What are the 3 requiremetns for production of x-ray?
- Source of electrons
- Potential dfiference
- Means of stopping the electrons quickly
What does filtration do?
hardnes the beam by removing low energy, long wavelength photons
Whats the primary reason fro filtration?
to eliminate x-ray photons that would cause increased radiation dose.
What is the most common filter material used for filtration?
Filtration can be expressed in what term?
Thickness of aluminum equivalency ( mm Al/eq)
What is Half value layer?
HVL is athe amoutn of absorbing material that will cut the intensity of the beam in half.
Whats inherent filtration?
Filtration that comes in with the tube ( glass casing, etc )
How thick in mm al/eq should total inherent filtraiton add to?
.5 to 1.0 mm al/eq
What is added filtration?
Added filtration is filtration used outside of the protecive housing and tube.
What is the average mm al/eq of added filtration?
1.0 mm al/eq
What is compound filtration?
Uses to ore more materials that go together to increase absorbing abilities.
What is compensation filtration?
Used to even out unequal subject densities
What is total filtration?
Inherent + Added filtration
How much filtration does the NCRP recommend for these kvp levels?
Below 50 KVP
50 - 70 KVP
Above 70 kvp
below 50 = .5 mm
50 - 70 = 1.5 mm
Above 70 = 2.5 mm
How thick should a primary barrier be?
How thick is a secondary barrioer?
What are the four types of dosimeters?
- Film Badges
- Optically Stimulated Luminescence
- Pocket Dosimeters
- Thermo Luminesecent Dosimeters.
Optically Stimulated Luminesence Dosimeters (OSL's) can measure as low as how much mrem?
1 mrem. very sensitive.
Whats good and whats bad about pocket dosimeters?
Pocket dosimeters give immediate reaings but are very expenive and must be read daily.
ALso it doesnt provide permanent record.
Thermoluminescent Dosimeters are made with what?
Material used for these are lithium fluorides crystals
What are radiation survey instruments?
Used to detect and measure radiation.
Whats the cutie pie used for?
meaures rate and cumulative exposure and measures a wide range of exposure within a few seconds.
Whats a geiger muller detector?
Instrument used in nuclear med facilities that allows rapid monitoring of radiation.