The purpose of the filter in the head of the x-ray unit is to remove _________

By Standard Number
1910.252 - General requirements.

Part Number:
Inhaltsverzeichnis Show
1910
Part Number Title:
Occupational Safety and Health Standards
Subpart:
1910 Subpart Q
Subpart Title:
Welding, Cutting and Brazing
Standard Number:
Title:
General requirements.
GPO Source:

[39 FR 23502, June 27, 1974, as amended at 40 FR 23073, May 28, 1975; 43 FR 49750, Oct. 24, 1978; 49 FR 5323, Feb. 10, 1984; 51 FR 34562, Sept. 29, 1986; 54 FR 24334, June 7, 1989; 55 FR 13696, Apr. 11, 1990; 61 FR 9227, March 7, 1996; 63 FR 1152, Jan. 8, 1998; 74 FR 46357, Sept. 9, 2009; 77 FR 17777, March 26, 2012]

Citation, DOI & article data

Citation:

Goel A, Jones J, Murphy A, et al. Filters. Reference article, Radiopaedia.org (Accessed on 10 Dec 2022) https://doi.org/10.53347/rID-29737

Filters are metal sheets placed in the x-ray beam between the window and the patient that are used to attenuate the low-energy (soft) x-ray photons from the spectrum. Filtering is the removal of these low energy x-rays from the beam spectrum which would otherwise not contribute to image quality but would add to patient dose and scatter. If unfiltered these low-energy x-ray photons are generally absorbed by superficial structures of the body and contribute to the entrance surface dose (ESD). As they are absorbed by the superficial structures they contribute minimally to image formation. Using a filter reduces the ESD and to a lesser extent effective dose for the patient 1. The units of filtration are expressed in mm of aluminum equivalence (mm Al eq).

There are two types of filtration 2:

inherent filtration from components in the x-ray tube, i.e. window, housing, cooling oil (equivalent to 0.5-1.0 mm Al)
added filtration from interchangeable metal sheets (Al, Cu, etc.)

Total filtration is the combined effect of inherent and added filtration, with US guidelines stating a minimum total filtration of 2.5 mm of aluminum is required for x-ray tubes operating above 70 kVp 3.

The added filtration component is customized (filter thickness, type of metal) for individual examinations and procedures (e.g fluoroscopy) and takes advantage of specific metals filtration characteristics (e.g. absorption edges) to improve image quality and contrast 4.

Beryllium is commonly used in mammography (which use low-energy photons) as it provides very little filtration. Other types of x-ray generally use aluminum, copper or tin.

Filtration reduces x-ray intensity, but not the maximum energy of the x-ray beam spectrum. The change in the shape of the beam spectrum with filtration is referred to as beam hardening. This is due to the loss of lower energy photons from a polychromatic beam. The average x-ray energy is increased and becomes more penetrating 6.

Quiz questions

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What is the purpose of x

Filtration is required to absorb the lower-energy x-ray photons emitted by the tube before they reach the target. The use of filters produce a cleaner image by absorbing the lower energy x-ray photons that tend to scatter more.

What is the purpose of aluminum filtration in the x

The purpose of the aluminum filter is to remove the low energy, long wavelength, and least penetrating x-rays from the x-ray beam. These x-rays are harmful to the patient and are not useful in producing a diagnostic-quality radiograph. X-ray machines operating at 70 kVp or above must have aluminum filtration of 2.5 mm.

What is the purpose of the aluminum filter in the x

The purpose of the aluminum filter is to remove the low-energy, long-wavelength, least penetrating x-rays from the beam. X-ray machines operating at 70 kVp or greater must have aluminum filtration of 2.5 mm.

What is the purpose of the filter or filtration quizlet?

Filtration removes a potion of the useful beam. The primary purpose of the collimator is filtration. Filtration that occurs outside the tube and housing is considered to be added filtration.