Compensating filters
Last revised by Jeremy Jones on 20 Sep 2021
Citation, DOI, disclosures and article data
Citation:
Murphy A, Jones J, Kusel K, Compensating filters. Reference article, Radiopaedia.org (Accessed on 19 Mar 2024) https://doi.org/10.53347/rID-58714
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rID:
58714
Article created:
3 Mar 2018,
Andrew Murphy ◉
Disclosures:
At the time the article was created Andrew Murphy had no recorded disclosures.
View Andrew Murphy's current disclosures
Last revised:
20 Sep 2021,
Jeremy Jones ◉
Disclosures:
At the time the article was last revised Jeremy Jones had no recorded disclosures.
View Jeremy Jones's current disclosures
Revisions:
3 times, by
3 contributors -
see full revision history and disclosures
Compensating filters are external, uniquely shaped; typically aluminum mounts often affixed to the collimator of the x-ray tube. The filters are used to limit the primary beam at an anatomical region during a specific examination that requires fine radiographic detail at both the 'denser' and 'less dense' regions, e.g. a horizontal beam lateral hip requiring detail at both the proximal and distal portion of the image.
The application determines the shape of the filter. The three most common compensating filters are:
- boomerang filter
- shaped like the indigenous Australian boomerang
- traditionally used during shoulder examination, it is placed behind the patient, with the thickest portion of the superior-lateral aspect of the shoulder
- boomerang filtration balances out the density of the soft tissue often during the shoulder examination
- trough filter
- channel shaped filter used during chest radiographs
- affixed to the collimator of the x-ray tube
- the thicker outer regions of the trough corresponding to the less dense aspects of the peripheral lungs
- wedge filter
- a wedge-shaped filter affixed to the collimator of the x-ray tube
- the thicker portion of the wedge is placed in the primary beam which passes through the less dense parts of the anatomy being imaged
- common uses
- horizontal beam hips, the thick portion of the wedge over the distal aspect of the femur
- AP foot, the thick portion of the wedge over the distal aspect of the foot
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References
- 1. A. Stewart Whitley, Charles Sloane, Graham Hoadley et al. Clark's Positioning in Radiography (Hodder Arnold Publication). (2005) ISBN: 9780340763902
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