Change:  thick slice CT scans in the posterior fossa. See also edge gradient effect.From GE: GE Medcyclopaedia Ring ArtefactsInsufficient exposure results in concentric circles in the center of the field of view.The ring artifact is seen here in the left lobe of the liver.   View changes from previous version. (Word count: 1120)

Change: Multi-slice scanners are prone to a similar type of transaxial image distortion due to helical interpolation as single-slice scanners. Their severity is reduced by the   View changes from previous version. (Word count: 881)

Change:  Overscan and underscan modes: The maximum discrepancy in detector readings occurs between views obtained toward the beginning and end of a 360° scan. Some scanner   View changes from previous version. (Word count: 761)

Change:  artifacts due to beam hardening. Article from: http://radiographics.rsna.org/content/24/6/1679.full Motion Artefacts Multislice Artefacts Partial Volume Artefacts Ring ArtefactsInsufficient exposure results in concentric circles in the center of the field of view.The ring artifact is seen here in the left lobe of the liver.   View changes from previous version. (Word count: 343)

Change: the beam becoming 'harder'. Metal Artefacts Motion Artefacts Multislice Artefacts Partial Volume Artefacts Ring ArtefactsInsuficientInsufficient exposure results in concentric circles in the center of the field of exposure.view.The ring artifact is seen here in the left lobe of the liver.Partial Volume Effect   View changes from previous version. (Word count: 96)

Change:  photons while the higher energy photons pass through to the detectors which results in the beam becoming 'harder'. Metal Artefacts Motion Artefacts Multislice Artefacts Partial Volume Artefacts Ring ArtefactsPartial Volume Effect   View changes from previous version. (Word count: 73)

Change: Beam Hardening ArtefactsMetal ArtefactsMotion ArtefactsMultislice ArtefactsPartial Volume ArtefactsRing Artefacts   View changes from previous version. (Word count: 14)