IMPACT OF THE COMBINED EFFECT OF EXOMASS-RELATED AND MOTION ARTIFACTS IN CONE BEAM COMPUTED TOMOGRAPHY

Abstract

BACKGROUNDExomass-related and motion artifacts are commonly observed in the everyday clinic and negatively affect cone beam computed tomography (CBCT) image quality. These 2 entities can be expected to occur in conjunction; however, they have only been assessed separately by the scientific community.OBJECTIVE(S)To assess quantitatively the combined effect of exomass-related and motion artifacts on voxel value parameters in CBCT.STUDY DESIGNA cylindrical phantom was manufactured containing 21 tubes filled with a radiopaque solution, allowing the inclusion of 3 titanium implants in the periphery to induce exomass-related artifacts. The phantom was mounted on a robot simulating 0.75-, 1.5-, and 3-mm movements (nodding/lateral rotation/tremor). CBCT images with/without exomass and with/without movements were acquired in duplicate in 3 units: Cranex 3Dx, Orthophos SL-3D, and X1 (with motion artefact correction). A cylindrical volume of interest was defined in each tube and voxel value means and standard deviations were assessed. For each CBCT volume, the 21 mean voxel values were averaged, providing the overall mean voxel value (MVV). The standard deviation (among the 21 values) was calculated, providing overall voxel value inhomogeneity (VVI). The standard deviations from each of the 21 volumes of interest were averaged, providing overall image noise. The effect of the diverse tested situations was inferred from a repeated-measures analysis of variance, followed by Sidak's test (α = .05).RESULTSOverall, images acquired with exomass showed significantly lower MVV and higher VVI and image noise (P ≤ .05). Motion artifacts aggravated exomass-related alterations. MVV and VVI were mostly affected by 3-mm nodding movements. Motion artifact correction eliminated the deleterious effect of movement.DISCUSSION/CONCLUSIONSCBCT voxel value parameters are altered by exomass-related artifacts, and this finding is aggravated in the presence of motion artifacts. Motion artifact correction effectively eliminated the deleterious effect of movement. Exomass-related and motion artifacts are commonly observed in the everyday clinic and negatively affect cone beam computed tomography (CBCT) image quality. These 2 entities can be expected to occur in conjunction; however, they have only been assessed separately by the scientific community. To assess quantitatively the combined effect of exomass-related and motion artifacts on voxel value parameters in CBCT. A cylindrical phantom was manufactured containing 21 tubes filled with a radiopaque solution, allowing the inclusion of 3 titanium implants in the periphery to induce exomass-related artifacts. The phantom was mounted on a robot simulating 0.75-, 1.5-, and 3-mm movements (nodding/lateral rotation/tremor). CBCT images with/without exomass and with/without movements were acquired in duplicate in 3 units: Cranex 3Dx, Orthophos SL-3D, and X1 (with motion artefact correction). A cylindrical volume of interest was defined in each tube and voxel value means and standard deviations were assessed. For each CBCT volume, the 21 mean voxel values were averaged, providing the overall mean voxel value (MVV). The standard deviation (among the 21 values) was calculated, providing overall voxel value inhomogeneity (VVI). The standard deviations from each of the 21 volumes of interest were averaged, providing overall image noise. The effect of the diverse tested situations was inferred from a repeated-measures analysis of variance, followed by Sidak's test (α = .05). Overall, images acquired with exomass showed significantly lower MVV and higher VVI and image noise (P ≤ .05). Motion artifacts aggravated exomass-related alterations. MVV and VVI were mostly affected by 3-mm nodding movements. Motion artifact correction eliminated the deleterious effect of movement. CBCT voxel value parameters are altered by exomass-related artifacts, and this finding is aggravated in the presence of motion artifacts. Motion artifact correction effectively eliminated the deleterious effect of movement.