RAD 120 - Ch 11 Filtration - Review Questions

What is filtration?

Filtration is the process of eliminating undesirable low-energy x-ray photons by the insertion of absorbing materials into the primary beam.

What is the standard filter material used in diagnostic radiography?

Aluminum is considered the standard filtering material, and all filtration can be expressed in terms of the thickness of aluminum equivalency (Al/Eq).

Define half-value layer.

The half-value layer (HVL) is that amount of absorbing material that will reduce the intensity of the primary beam to one-half its original value.

What is inherent filtration?

Filtration that is a result of the composition of the tube and housing is called inherent filtration because it is a part of these structures.

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.

What are the two most common compensating filters?

The two most popular compensating filters are the wedge filter and trough filter (sometimes called a double wedge).

What is total filtration?

Total filtration is equal to the sum of inherent and added filtration.

How does filtration affect patient dose and beam intensity?

Filtration reduces the patient dose by eliminating low-energy photons from the primary x-ray beam. It also removes a portion of the useful beam, which reduces the overall beam intensity.