X-ray artifacts

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 digital radiography (DR).

Common causes

• improper handling of the films
• errors while processing the films
• patient movement while taking the image

Common artifacts (all forms of radiography)

• motion artifact
  • due to patient movement resulting in a distorted image
• image compositing (or twin/double exposure)
  • superimposition of two structures from different locations due to double exposure of same film/plate
• grid cut-off
• 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.).
• debris in the housing 
  • debris in the housing caused by the collimator tube can cause small trapezoidal regions, indicative of lead shavings 

Film radiography artifacts

• 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

Computed/digital radiography artifacts

• detector image lag or ghosting
  • latent image from previous exposure present on current exposure
• incorrect detector orientation i.e. upside-down cassette
  • spoke like radiopaque lines (case 6)
• backscatter
  • electronics are visible on the exposed image
  • increased radiation exposure required for portable DR (digital radiography) examinations
• stitching artifacts
  • occur when two separate DR or CR (computed radiography) images are merged into a single image (see case 3)
• over exposure
• dead pixel artifact
• signal dropout
  • large areas of signal loss, due to detector drop
• speckled radiopaque spots
  • due to detector drop
• detector calibration limitation
  • faint radioopaque 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
  • similar to ghosting, however, the digital detector not being calibrated when promoted is the cause 
• electronic shutter failure
  • 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 reexamination)
• values of interest misread
  • 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
  • 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
  • faint grid lines present on an image, with no grid cut off

Siehe auch:

• thorakale Implantate / Devices
• Artefakte im Röntgenbild des Thorax
• Röntgen-Thorax

und weiter:

• Raster Artefakt