Filtration Vocab Quiz for POI

Added Filtration

Any filtration that occurs outside of the xray tube and housing.

AL/EQ (Aluminum Equivalent)

The absorption property of a material is expressed as how well the material absorbs xray photons as compared to how well aluminum absorbs xray photons.

Collimator

The mirror of the collimator provides approximately 1mm AL/EQ filtration.

Compensating Filter

An absorber that compensates for unequal absorption of the subject- used to even out unequal densities from unequal body part thickness. E.g. thoracic spine where the body is thinner near the neck than in the abdomen.

Compound Filter

Uses two or more materials that complement one another in their absorbing abilities. Each layer absorbs the characteristic photons created by the previous layer.

Filter

Any material designed to effectively absorb photons from the xray beam (purpose is to reduce low energies and reduce patient dose)

Filtration

The process of eliminating undesirable low- energy xray photons by inserting an absorbing material into primary beam.

Half-Value Layer

That amount of absorbing material that will reduce beam intensity to half its original amount. Code of Federal Regulations establishes requirements equipment HVL.

Inherent Filtration

Filtration as a result of the composition of the tube and housing- typically amounts to 0.5 to 1.0mm of AL/EQ with most coming from the tube window itself.

Thoreaus Filter

Compound filter used in radiation therapy which combines tin, copper, and aluminum, in that order.

Total Filtration

The sum of inherent and added filtration of the tube. (Does not include compound or compensating filters). National Council on Radiation Protection requires that equipment operating above 70 kVp must have a minimum filtration of 2.5mm AL/EQ.

Trough Filter

Compensating filter most commonly used to visualize structures of the mediastinum without overexposing the lungs.

Wedge Filter

Compensating filter shaped in a wedge, used to compensate for unequal thickness of the anatomy of interest; e.g. thoracic spine, thigh, foot, etc.