## 3 Results  
Table 2 shows the results of radiation doses to highly radiosensitive organs measured with the maxillary median placed at the center of rotation. Table 3 shows the results of radiation doses to highly radiosensitive organs measured with the maxillary right canine tooth placed at the center of rotation. For both the maxillary median and right canine, the parotid gland doses were significantly higher than the other organ doses examined in the 4 \(\times\) 4 cm FOV. Compared with the 4 \(\times\) 4 cm FOV, the sublingual gland doses increased significantly at the 6 \(\times\) 6 cm FOV. Compared with the maxillary median, the dose to the right sublingual gland was slightly higher in the 6 \(\times\) 6 cm FOV with the maxillary right canine tooth placed at the center of rotation. When the FOV was reduced from 6 \(\times\) 6 cm to 4 \(\times\) 4 cm, the reduction rates of the doses to the lenses, thyroid lobes, parotid glands, and sublingual glands were approximately 38.2-62.5%, 58.8-71.2%, 31.7-35.9%, and 84.8-90.8%, respectively. When the rotation angle was reduced from 360\({}^{\circ}\) to 180\({}^{\circ}\), the reduction rates of the doses to the lenses, thyroid lobes, parotid glands, and sublingual glands were approximately 53.3-69.0%, 31.8-58.1%, 9.3-18.9%, and 20.1-45.0%, respectively. Table 4 shows a comparison of this study with the study by [PERSON] et al. [45]. The measured values cannot be directly compared because of the different measurement methods and imaging conditions. Therefore, the relative differences in radiation doses were compared. [PERSON] et al. reported that the effect of FOVs and rotation angles on organ-absorbed doses in adult males. To measure the radiation dose for each exposure, thermoluminescent dosemeter (TLD) chips of the type TLD-100 (LiF:Mg,Ti) were used. Some of the dosimeters were inserted into the phantom. A tube voltage of 90 kV and tube current 5 mA were used. Lens, thyroid, and salivary gland doses were measured in the maxillary canine at the 4 \(\times\) 4 cm FOV and in the maxillary midline at the 6 \(\times\) 6 cm FOV. The salivary glands differed from this study because they were not divided into parotid, submandibular and sublingual glands. In addition, in this study, the number of measurements was three and the standard deviation (SD) was calculated, but in [PERSON] study, the number of measurements was not stated, and the SD was not calculated. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & \multicolumn{4}{c}{**This Study**} & \multicolumn{4}{c}{**[PERSON] et al. [45]**} \\ \hline Position & Maximly canine & \multicolumn{4}{c}{Maxillary median} & \multicolumn{4}{c}{Maxillary canine} & \multicolumn{4}{c}{Maxillary median} \\ Tube voltage (AV) & \multicolumn{2}{c}{90} & \multicolumn{2}{c}{90} & \multicolumn{2}{c}{90} & \multicolumn{2}{c}{90} \\ Tube current (mA) & \multicolumn{2}{c}{3} & \multicolumn{2}{c}{3} & \multicolumn{2}{c}{5} & \multicolumn{2}{c}{5} \\ FOV (cm) & \multicolumn{2}{c}{4 \(\times\) 4} & \multicolumn{2}{c}{6 \(\times\) 6} & \multicolumn{2}{c}{4 \(\times\) 4} & \multicolumn{2}{c}{6 \(\times\) 6} \\ Rotation angle (\({}^{\circ}\)) & 360 & 180 & 360 & 180 & 360 & 180 & 360 & 180 \\ Exposure time (s) & 17.5 & 9.0 & 17.5 & 9.0 & 17.5 & 9.0 & 17.5 & 9.0 \\ \hline Lens & 38.3 \(\pm\) 0.00 & 141 \(\pm\) 0.50 & 72.7 \(\pm\) 0.49 & 26.1 \(\pm\) 0.48 & 174 & 95 & 608 & 288 \\ Thyroid & 51.1 \(\pm\) 0.49 & 25.0 \(\pm\) 0.00 & 147.4 \(\pm\) 0.95 & 72.4 \(\pm\) 0.00 & 108 & 50 & 175 & 88 \\ Carotid gland & 225.4 \(\pm\) 0.98 & 199.5 \(\pm\) 0.50 & 326.3 \(\pm\) 0.50 & 284.3 \(\pm\) 0.48 & - & - & - & - \\ Sublingual gland & 67.7 \(\pm\) 0.00 & 437 \(\pm\) 0.45 & 456.7 \(\pm\) 2.26 & 338.0 \(\pm\) 0.00 & - & - & - & - \\ Suliary gland & - & - & - & 845 & 573 & 2192 & 1583 \\ \hline \multicolumn{1}{c}{Data in this study are presented as mean \(\pm\) standard deviation.} & \multicolumn{2}{c}{} & & & & \\ \hline \end{tabular}
\end{table}