X-ray Filtration Practice Flashcards

Vocabulary-style flashcards covering the concepts, types, and measurements of X-ray filtration.

Filtration

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

Hardening the beam

A term for filtration derived from its ability to remove low-energy (soft) photons, thereby increasing the average energy of the beam.

Kilo-electron volt (keV)

The unit used to measure the energy of an individual x-ray; it is also used to identify electron binding energy.

Kilo Voltage Peak (kVp)

The kinetic energy of the projectile electron resulting from the voltage applied to the x-ray tube.

X-ray Quality

The penetrability of the x-ray beam, or its ability to penetrate deeper into tissue; high-energy photons result in high-quality beams.

Filter

Any material designed to selectively absorb photons from the x-ray beam, typically added between the source and the patient.

Aluminum (Al)

The standard filtering material used in diagnostic radiology due to its availability, effectiveness in removing low-energy x-rays, and low cost.

Aluminum Equivalency (Al/Eq)

The standard unit for expressing the thickness of filtration, capturing the collective effect of materials like the mirror and collimator plastic.

Half-value layer (HVL)

The amount of absorbing material required to reduce the intensity of the primary beam to $\frac{1}{2}$ of its original value.

Inherent Filtration

Filtration resulting from the composition of the tube and housing, such as the glass envelope, dielectric oil, and glass window.

Beryllium

A material with an atomic number of $4$ used in mammographic tube windows to reduce inherent filtration to $0.1\,mm\,Al/Eq$.

Added Filtration

Any filtration occurring outside the tube and housing and before the image receptor, such as the collimator device.

Compound Filtration

A filter using two or more materials that complement one another, where each layer absorbs the characteristic photons created by the previous layer; also known as a K-edge filter.

Thoraeus filter

A compound filter used in radiation therapy composed of tin ($Z=50$), copper ($Z=29$), and aluminum ($Z=13$).

Compensating Filtration

Filters designed to solve problems involving unequal subject densities by producing a more uniform image receptor exposure.

Wedge and Trough filters

The two most popular types of compensating filters.

Total Filtration

The sum of inherent filtration and added filtration, excluding any compound or compensating filtration.

Technical Factors

Settings that must be increased as filtration increases to maintain the same image receptor exposure after the loss of useful beam intensity.