RAD 120 - Ch 11 Filtration - Key Terms & Definitions

Added Filtration

any filtration that occurs outside the tube and housing before the image receptor

Compensating Filter

usually designed to solve a problem involving unequal subject densities

Compound Filter

the use of two or more materials to complement one another in their absorbing abilities; also known as K-edge filters

Filter

any material designed to selectively absorb photons from the x-ray beam

Half-Value Layer (HVL)

the amount of absorbing material that will reduce the intensity of the primary beam to half of its original value

Inherent Filtration

A result of composition of the tube and housing

K-edge Filter

the use of two or more materials to complement one another in their absorbing abilities; also known as compound filters

Thoraeus Filter

A type of compound filter consisting of tin, copper, and aluminum, in that order, typically used in radiation therapy.

Total Filtration

the sum of inherent and added filtration

Trough Filter

A double wedge compensating filter added to the primary beam to produce more consistent exposure to the image receptor

Wedge Filter

Most common kind of compensating filter which is used to radiograph body parts that vary considerably, such as the foot.

Filtration

eliminates the low-energy x-ray photons by inserting absorbing materials into the primary beam

Best range for significant soft tissue penetration

30-40keV

Filtration is expressed in terms of

Aluminum Equivalency (Al/Eq)

Filtrations Effect on Output

- filtration reduces patient exposure, but also removes a portion of useful beam affecting IR exposure

- To compensate for the loss of exposure when filtration is increased, technical factors must be increased to maintain the same image receptor exposure