Chapter 11 Notes Flashcards
filtration is the process of
eliminating undesirable x-ray photons by the insertion of absorbing materials into the primary beam
filter
any material designed to selectively absorb photons from the x-ray beam
most common filter material used
aluminum
aluminum filtration can be expressed in terms of
thickness of aluminum equivalency (Al/Eq)
half-value layer (HVL)
amount of absorbing material that will reduce intensity of primary beam to one-half its original value
filtration is either
inherent or added
inherent filtration
filtration that is the result of the composition of the tube and housing; it is a part of these structures
added filtration
any filtration that occurs outside the tube and housing and before the IR
the collimator device adds approximately _____ to the beam
1 Al/Eq
compound filter uses
two or more materials that complement one another in their absorbing ability
compensating filter usually designed to
solve a problem involving unequal subject density
two common compensating filters
wedge and trough
total filtration is equal to
sum of inherent and added filtration
filtration is also called
“hardening” the beam
filtration increases
average beam energy
inherent filtration examples
glass envelope, dielectric oil bath, glass window of housing
largest factor of inherent filtration
glass envelope
inherent filtration increases as
tube ages
compound filtration is also known as using
K-edge filters
K-edge filters
each layer absorbs characteristic photons created in previous layer
compensation filtration is used to
compensate for variations in parth thickness/density
other common filter material
copper
filtration beyond _____ has an undesirable effect and is of little clinical value
3 mm/Al
