Stability of voxel values in cone-beam computed tomography
Tóm tắt
Measurements of jaw bone density are important for dental implants, and stable voxel values in cone-beam computed tomography (CBCT) for dental use are necessary for their evaluation. The purpose of this study was to clarify the stability of voxel values in CBCT. Cylindrical phantoms composed of the same material were set at the median anterior region and left and right first molar regions of an acrylic vessel filled with water. Three kinds of cylindrical phantoms made of polyvinyl chloride, polyacetal polyoxymethylene, and polycarbonate were evaluated. CBCT images were obtained using Alphard VEGA and 3D eXam i systems. Circular regions of interest were superoinferiorly set at five levels, and the voxel values were averaged. The mean differences were calculated on the basis of the voxel values at a central level of the anterior region. The mean voxel values for polyvinyl chloride, polyacetal polyoxymethylene, polycarbonate, and water were 1057, 293, 137, and 102 in Alphard VEGA and 554, 48, −127, and −202 in 3D eXam i, respectively. There were significant differences between sites and levels in Alphard VEGA and between sites in 3D eXam i. The mean differences for polyvinyl chloride, polyacetal polyoxymethylene, polycarbonate, and water were 73, 24, 18, and 18 in Alphard VEGA and 72, 49, 43, and 40 in 3D eXam i, respectively. The mean differences for polyvinyl chloride, close to the cortical bone density, were larger than those for polyacetal polyoxymethylene, polycarbonate, and water in Alphard VEGA and 3D eXam i.
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