EVALUATION OF BEAM HARDENING ARTIFACTS CREATED BY RESTORATIVE AND METAL MATERIALS IN THE EXOMASS BY CONE-BEAM COMPUTED TOMOGRAPHY IMAGING

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Shirin Ghasemi , Sedigheh Razi, Tahmineh Razi

Abstract

: CBCT has a high importance in the diagnosis and treatment plan of the head and neck. Artifacts,
including metal-related artifacts, also have important effects in the field of view (FoV) on the image quality
and clutter, as well as difficulty of diagnosis. The present study was performed to examine out-of-FoV metal
artifacts (exomass) with respect to the number of metals, two types of FoV, and different exomass distances.
Methods: In this descriptive-analytical study, 192 images of CBCT scans in the axial section of beam
hardening artifacts were prepared and examined by irradiating on a dry human skull. The artifact intensity
was assessed based on the type, number of metals, types of FoV, and different distances from the FoV by
Chi-square test and SPSS 24 software.
Results: Results of the artifact intensity and the type of metal in the axial view were expressed as P-value =
0.001. Based on the number of metals, the highest artifact intensity was observed in the placement of one
metal with a frequency of 9.4%. A comparison of FULL and ZOOM FoVs revealed a P-value of 0.899.
Results of the artifact intensity based on different out-of-FoV (exomass) distances were reported with Pvalue < 0.01.
Conclusions: In this study, the highest and the lowest intensities of artifacts were observed with amalgam
and titanium, respectively. In terms of the number and placement, the highest and the lowest intensities were
observed in one and two metal placements, respectively, due to dissimilar thickness of simulated soft tissue
relative to the position of metals. No significant results were obtained by a comparison of FULL and ZOOM
FoVs. In terms of different distances from the FoV, the highest artifact intensity was obtained at the edge of
the FoV (0 cm) and no artifact was observed at a distance of 14 cm from the edge of the FoV.


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