X-ray artifacts can present in a variety of ways including abnormal shadows noted on a radiograph or degraded image quality, and have been produced by artificial means from hardware failure, operator error and software (post-processing) artifacts.
There are common and distinct artifacts for film, computed (CR) and direct digital radiography (DR).
On this page:
Common artifacts (all forms of radiography)
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motion artifact
due to patient movement resulting in a distorted image
radiopaque objects on/external to the patient (e.g. jewelry (e.g. necklaces, piercings), clothing (e.g. buttons), hair (e.g. ponytail, hair braids etc.)
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image compositing (or twin/double exposure)
superimposition of two structures from different locations due to double exposure of same film/plate
only in film and computed radiography
similar appearance to detector lag/ ghosting artifact in direct digital radiography (see below)
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debris in the housing 4
debris in the housing caused by the collimator tube can cause small trapezoidal regions, indicative of lead shavings
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parallax effect: whenever the object is off-center or tilted in relation to the central beam, the projected image might get distorted, inducing incorrect measurements5. An example of this effect would be the apparent narrowed disc spaces in the low thoracic region in lumbar radiographs (i.e., the object off-center, with diverging beams in relation to the focal point6)
Film radiography artifacts
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finger marks
improper handling with hands
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clear film
malfunction of the machine or placing the film in the fixer before developer solution
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static electricity
black “lightning” marks resulting from films forcibly unwrapped or excessive flexing of the film
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crescent-shaped black lines
due to fingernail pressure on the film
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crescent-shaped white lines
due to cracked intensifying screen
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black film
complete exposure to light.
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clear spots
air bubbles sticking to film during processing
fixer splashed on film prior to developing
dirt on the intensifying screen
Common artifacts in computed and direct digital radiography
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stitching artifacts
occur when two separate CR or DR images are merged into a single image (case 3)
Computed radiography artifacts
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incorrect detector orientation i.e. upside-down cassette
spoke like radiopaque lines (case 6)
Direct digital radiography artifacts
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detector image lag or ghosting
latent image from previous exposure present on current exposure
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backscatter
electronics are visible on the exposed image
increased radiation exposure required for portable DR (digital radiography) examinations
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signal dropout 4
large areas of signal loss, due to detector drop
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speckled radiopaque spots 4
due to detector drop
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detector calibration limitation 4
faint radiopaque striping (often vertical) in the background of an image, yet not evident on the anatomy
this artifact should be carefully examined, if it does not interfere with the anatomy, it is not a detector failure/grid cut off, rather a limitation of the detector calibration
often seen as lower exposure
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failure of detector offset correction 4
similar to ghosting, however, the digital detector not being calibrated when promoted is the cause
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electronic shutter failure 4
the digital image often will have obscurely shaped, tight collimation that defies logic
often a computer error often fixed with recollimation post exam (this should be explored before re-examination)
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values of interest misread 4
image appears washed out and underexposed
this is often due to a largely collimated area of smaller anatomy i.e. a patella protection
tighter digital collimation in conjunction with reprocessing will correctly assign the correct values of interest
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mid grey clipping 4
loss of contrast in areas of different pixel density yet not change in density can be seen i.e. the metal on a knee replacement
due to poor contrast enhancement
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grid-line suppression failure 4
faint grid lines present on an image, with no grid cut off