抄録
Objective : To evaluate quantitatively the metal artifacts on 3DX Accuitomo images using the titanium
cylinders in relation to various exposure protocols.
Materials and method : For the evaluation of artifacts, titanium cylinders were fabricated. The titanium
cylinders of 2.99 and 3.49 mm were installed in anterior and posterior segments of the plastic model of the
mandible. Cylinders with heights of 15.07 mm for 2.99 mm and 15.06 mm for 3.49 mm diameter were prepared
from a titanium rod. The cylinders were placed 10 mm from each other, and their positions were in two
central incisors for anterior and molar regions for the posterior segment. CBCT examinations were performed
with 3DX Accuitomo, FPD type (Morita Corp., Kyoto, Japan). The titanium cylinders were imaged at the same
position at tube voltages of 60 and 90 kV, a tube current of 4 mA, and an exposure time of 17 seconds. The
voxel size was 0.125 mm. The heights of the cylinders were measured in coronal and sagittal images. Diameter
measurement was performed at the center of the cylinder. The anteroposterior (AP) and mediolateral (ML)
diameters of cylinders were measured in axial images. All data were evaluated with the Image J and OsiriX
image analysis software.
Results : In the measurement of the heights of the titanium cylinders, the mean heights deviated from 100.85%
to 101.46%, and 100.59% to 101.12 % for a single cylinder for 60 and 90 kV, respectively. For double cylinders,
the mean heights were from 101.39% to 101.72%, and 101.12% to 101.12% for 60 and 90 kV, respectively. The
mean diameters anteroposteriorly and mediolaterally were (102.86% to 104.01%, and 102.29% to 102.67%; and
102.00% to 103.01%, and 101.67% to 101.71%) for a single cylinder for 60 and 90 kV, respectively. For double
cylinders, the mean diameters anteroposteriorly and mediolaterally were (102.86% to 104.86%, and 100.28% to
104.01%; and 102.86% to 104.01%, and 102.00% to 102.67%) for 60 and 90 kV, respectively.
Conclusion : CBCT is used as an alternative to conventional CT for dental diagnosis. Artifacts can degrade
the quality of images, sometimes causing instability in the diagnosis. There are some factors that may cause
artifacts, such as patient positioning and the presence of metallic materials. However, for determining the
bone quality of the mandible, it is necessary to evaluate preoperatively metal artifacts for successful implant
installation.
