Department of Oral and Maxillofacial Radiology, School of Dentistry, Jeonbuk National University, Gunjiro-20, Jeonju, South Korea.
Oral Radiol. 2021 Jul;37(3):385-394. doi: 10.1007/s11282-020-00458-7. Epub 2020 Jul 7.
To reduce inter-implant metal artifacts in cone-beam CT (CBCT) imaging by adjusting angular position of the subject relative to the source-detector plane.
Two dental implants were placed in a block made of homogeneous dental impression material. Using a custom-made apparatus, the specimen was scanned with a CBCT machine at seven different angles (0°, 15°, 30°, 45°, 60°, 75°, and 90°) along three different spatial axes, yielding 21 experimental groups. Thirteen volumes of interest (VOI) including inter- and peri-implant areas were selected from each axial reconstruction perpendicular to the implants. Gray values (GVs) of each pixel within these VOIs were measured. Mean differences in GV (ΔGV) between the VOIs and control area were calculated and expressed as a percentage. These ΔGVs from different spatial angle were compared and analyzed by Welch's analysis of variance (ANOVA) and linear regression using SPSS 25.0 software.
As alpha angle increased, the ΔGV of the inter-implant area increased from - 62.02% to near-zero while the standard deviation decreased. Welch's ANOVA and linear regression analysis revealed ΔGV increased significantly with alpha angle (p < 0.001, R = 0.406). VOIs on the extension line of two implants showed similar results. After adjusting the beta and gamma angles, there was no significant change in ΔGV.
Increasing the alpha angle can reduce metal artifacts in the inter-implant area in CBCT images.
通过调整受检者相对于源探测器平面的角度位置来减少锥形束 CT（CBCT）成像中的种植体间金属伪影。
将两个牙种植体放置在均质牙科印模材料制成的块体中。使用定制的设备，以七种不同的角度（0°、15°、30°、45°、60°、75°和 90°）沿三个不同的空间轴用 CBCT 机对标本进行扫描，产生 21 个实验组。从每个轴向重建中垂直于种植体选择 13 个包括种植体间和种植体周区域的感兴趣体积（VOI）。测量每个 VOI 内每个像素的灰度值（GV）。计算这些 VOI 与对照区域之间的 GV 均值差异（ΔGV），并表示为百分比。使用 SPSS 25.0 软件通过 Welch 方差分析（ANOVA）和线性回归对来自不同空间角度的这些ΔGV 进行比较和分析。
随着α角的增加，种植体间区域的ΔGV 从-62.02%增加到接近零，而标准偏差减小。Welch ANOVA 和线性回归分析显示，ΔGV 随α角显著增加（p<0.001，R=0.406）。两个种植体延伸线上的 VOI 也显示出类似的结果。调整β和γ角后，ΔGV 没有明显变化。
增加α角可以减少 CBCT 图像中种植体间区域的金属伪影。
