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Imaging1 chap10
Imaging1. chap 10 FILTRATION
Question | Answer |
---|---|
Filtration is | eleminating undesirable low energy photons by insertion of absorbing materials into the primary beam |
Significant soft tissue penetration occurs between ___ and ___ keV. | 30-40, less than that will not have enough energy to exit the patient and contribute to the image so they are undiserable. |
Aluminum is the standard filtering material, all filtration can be expressed in terms of the thickness of ? | aluminum equivalency (Al/Eq) |
Filtration is expressed in terms of what? | Half Value Layer (HVL) |
HVL is? | amount of absorbing material that will reduce the intensity of the primary beam to one half its original value. |
Inherent filtration? Added? | inherent- in the design of the tube added- between the tube and IR |
A typical x-ray tube might have a total inherent filtration of what? | .5-1.0 mm Al/Eq |
Aluminum atomic #? | 13 |
Collimators average _____ Al/Eq, most of which comes from the what? | 1.0 mm Al/Eq. the silver on the mirror situated in the beam. |
A compound filter is aka? | K-edge filters. |
Compound filters place the _____ material closest to the tube and the _____ material closest to the patient. | highest atomic number, lowest |
Thoraeus filter combines... | Tin, copper, and aluminum. In that order. |
Compound filter. The _____ keV K-shell characteristic radiation produced by the aluminum filter is absorbed in the air between the filter and the patient. | 1.5 keV |
Two most popular compensating filters? | Wedge and trough. Increase kVp by 8-10 when using them |
Total filtration is? | The sum of inherent and added filtration. |
Recommended minimum total filtration levels: Below 50 kVp= 0.5 mm aluminum 50-70 kVp= 1.5 mm aluminum Above 70kVp= 2.5 mm aluminum | ON registry |