Filtratrion Flashcards
What is the function of FILTRATION?
Eliminates undesirable low energy X-ray photons by absorbing materials into the primary beam
What is the Half Value Layer? (HVL)
Amount of filtration needed to reduce the beam to half of its original intensity
Below 51 = 0..5 Al/Eq
51-70 = 1.5 Al/Eq
Above 70 = 2.5 Al/Eq
What is the standard filtering material?
Aluminum (Al/Eq)
(Al/Eq = Aluminum Equivalency)
In x-ray machines that operate between 51-70 kvp, the minimum amount of required filtration is?
1.5 Al/Eq
In x-ray machines that operate below 51 kvp, the minimum amount of required filtration is?
0.5 Al/Eq
A filter made of one or more material is called?
Compound Filter
In x-ray machines that operate above 70 kvp the minimum amount of required filtration is?
2.5 Al/Eq
Increasing the thickness of a filter will _____ patient dose
(Increase, decrease, not affect)
Decrease
Any material designed to selectively absorb photons from the X-ray beam is called a ?
Filter
Thoraeus filter combines these 3 materials
(List all 3)
- Tin
- Copper
- Aluminum
Filtration that is a result of the composition of the tube and housing is called ?
Inherent Filtration
Which material can be used as a compensating filter material? (List all 3)
- Clear Pb or plastics
- Saline
- Aluminum
Problems of uneven image receptor exposure due to heel effect is solved by a ___ ?
Compensating Filter
How do you find the average energy?
Add up all of the photons and divide by the # of photons
Does peak energy ever change?
No
Should the average energy be higher or lower than the original intensity after filtering?
Higher
True or False
The thickest portion of the wedge filter is placed over the less dense part of the patient
True
Does filtering soften or harden?
Harden
What is total filtration?
The sum of inherent and added filtration
When more than one filtering material is used, as in a compound filter, how are the materials arranged in relationship to the X-ray source?
Compound filters place the HIGHEST atomic number material closest to the tube and the LOWEST atomic number material closest to the patient
The final layer is aluminum
What is the final layer?
Aluminum
What is aluminum’s atomic number?
13