M8 - Filtration

Filtration

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

hardening the beam

Filtration is sometimes called ______ since it removes the low-energy (soft) photons.

Filtration

______ removes low-energy photons (long- wavelength or “soft” x-rays) from the beam by absorbing them and permits higher energy photons to pass through. This reduces the amount of radiation received by the patient.

Filter

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

Aluminum

________ is the most common filter material used.

• Glass

• Oil

• Copper

• Tin

Other materials used to become filters:

Aluminum

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

Filtration

_______ is also expressed in terms of half-value layer.

half-value layer (HVL)

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

Filtration

________ occurs at various points between the x-ray tube and the image receptor.

Inherent filtration

_________ is a result of the composition of the tube and housing because it is part of these structures.

0.5-1.0 mm Al/Eq

A typical x-ray tube might have a total inherent filtration of ________.

Added filtration

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

Filtration

________ materials are selected to absorb as many low-energy photons as possible while transmitting a maximum number of high-energy photons.

compound filtration

A _________ uses two or more materials that complement one another in their absorbing abilities.

Compound filters

__________ place the highest atomic number material closest to the tube and the lowest atomic number material closest to the patient.

compensation filter

A __________ is usually designed to solve a problem involving unequal subject densities.

1. Wedge Filter

2. Trough Filter (double wedge)

The 2 most popular compensating filters are:

wedge filter

A ________ can be useful for procedures on the thoracic spine, the feet and the lower extremities (e.g., venography and femoral angiography).

Trough filter

A __________ is useful to even the density differences between the mediastinum and the lungs on a chest radiograph.

Total Filtration

_________ is equal to the sum of inherent and added filtration and does not include any compound or compensating filters that may be added later.

National Council on Radiation Protection and Measurements

The __________ recommends minimum filtration levels for diagnostic radiography.