## 3 Results  
### CT Image Metal Artifact Evaluation  
Theoretically, it is known that the higher the tube voltage, the less the occurrence of metal artifacts [17, 18]. In this study, the degree of the existing metal artifact generation environment was compared and evaluated according to changes in tube voltage and tube current. The HU values of the inner and outer areas of the image acquired with high tube voltage decreased in the data without iMAR application (Table 1).  
In this study, the degree of occurrence of artifacts before/after applying the iMAR technique under similar image acquisition condition was of interest. Figure 3 shows the signal intensity of the artifact according to the changes in image acquisition parameters and iMAR application.  
As shown in Figure 3a, the HU value decreased as the tube voltage increased in the image without iMAR application. In addition, the signal change in the artifact, according to the change in tube current, is shown in Figure 3b. Analysis of the HU values of the inner and outer sections before and after iMAR application under the same conditions revealed lower average values in all conditions (Table 1). The change in HU value according to the change  
Figure 2: Reference phantom composition and metal artifact measurement. (**a**) A prosthesis made of nickel alloy was inserted into the right mandibular area first and second molars and first premolars. (**b**) Image acquired under 120 kVp and 50 mAs. The left image is a non-iMAR image, and the right image was acquired after iMAR. The solid line drawn in the inner and outer areas was used to measure artifacts, as described in the Materials and Methods section.  
in tube current did not increase significantly in the absence of iMAR in contrast to changes in the tube voltage condition. In this experiment, the effect of a beam hardening artifact was greatly affected by kVp rather than tube current. In addition, the occurrence of artifacts before and after iMAR application under each imaging acquisition parameter is expressed in Tables 1 and 2, and lower HU values were confirmed in all experimental conditions for the images subjected to iMAR. The lowest HU value was obtained at 120 kVp and 80 mAs. In addition, the greatest difference in HU value before and after iMAR application occurred at 80 kVp and 50 mAs.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multicolumn{2}{c}{**80 kVp 50 mAs**} & \multicolumn{2}{c}{**100 kVp 50 mAs**} & \multicolumn{2}{c}{**120 kVp 50 mAs**} \\ \hline \hline \multicolumn{2}{c}{**Inner Area**} & **Outer Area** & **Inner Area** & **Outer Area** & **Inner Area** & **Outer Area** \\ \hline \hline iMAR & \(-501.20\pm 369.24\) & \(-720.80\pm 631.69\) & \(-434.11\pm 432.70\) & \(-704.18\pm 318.15\) & \(-438.65\pm 344.62\) & \(-575.63\pm 425.25\) \\ non iMAR & \(-76.92\pm 631.69\) & \(-5.099\pm 829.2\) & \(-98.083\pm 457.227\) & \(-120.738\pm 669.435\) & \(-298.416\pm 288.370\) & \(-278.274\pm 461.582\) \\ \hline \hline \end{tabular}
\end{table}
Table 1: Average artifact signal intensity (Hounsfield unit) before and after iMAR application, according to changes in tube voltage.  
Figure 3: The HU change according to the distance of region of interest under each inspection condition before and after iMAR. (**a**) Change in HU value of inner area according to tube voltage change. In the absence of iMAR, the HU value decreased as the tube voltage increased, and following iMAR, the HU did not change significantly. (**b**) Change in HU value of the outer area according to change in tube current.