X-ray artifacts

Last revised by Giovanni Brondani Torri on 1 Apr 2024

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).

  • 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.)

  • 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)

  • grid cut-off

  • debris in the housing 4 

    • debris in the housing caused by the collimator tube can cause small trapezoidal regions, indicative of lead shavings

  • 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)

  • finger marks

    • improper handling with hands

  • clear film

    • malfunction of the machine or placing the film in the fixer before developer solution

  • static electricity

    • black “lightning” marks resulting from films forcibly unwrapped or excessive flexing of the film

  • crescent-shaped black lines

    • due to fingernail pressure on the film

  • crescent-shaped white lines

    • due to cracked intensifying screen

  • black film

    • complete exposure to light.

  • clear spots

    • air bubbles sticking to film during processing

    • fixer splashed on film prior to developing

    • dirt on the intensifying screen

  • stitching artifacts

    • occur when two separate CR or DR images are merged into a single image (case 3)

  • over exposure

  • incorrect detector orientation i.e. upside-down cassette

    • spoke like radiopaque lines (case 6)

  • detector image lag or ghosting

    • latent image from previous exposure present on current exposure

  • backscatter

    • electronics are visible on the exposed image

    • increased radiation exposure required for portable DR (digital radiography) examinations

  • dead pixel artifact

  • signal dropout 4

    • large areas of signal loss, due to detector drop

  • speckled radiopaque spots 4

    • due to detector drop

  • 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

  • failure of detector offset correction 4

    • similar to ghosting, however, the digital detector not being calibrated when promoted is the cause 

  • 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)

  • 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

  • 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

  • grid-line suppression failure 4​​

    • faint grid lines present on an image, with no grid cut off

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