## 3 Results
### Patient Radiation Dose Determination  
The percent differences between the CTDI\({}_{\text{vol}}\) displayed on the CT scanner monitors and the measured CTDI\({}_{\text{vol}}\) were within the acceptable limit of \(\pm 20\%\). Table 2 shows the patient radiation doses for CT brain scanning protocols across the five age groups. The CTDI\({}_{\text{vol}}\) values were consistent across the age groups of 0 to 6 months, 6 months to 3 years, 3 to 6 years, and 6 to 12 years. The CTDI\({}_{\text{vol}}\) for the 12-to-15-year age group showed a slight variation, with a median (IQR) value of 40.1 (40.1, 41.2) mGy. The CTDI\({}_{\text{vol}}\) increased with age, and, similarly, the median values of DLP and organ doses in the brain and eye lenses also increased with age. Although the CTDI\({}_{\text{vol}}\) remained consistent within each age group, the SSDE\({}_{\text{Dw}}\) values varied. In the 0-to-6-month age group, the CTDI\({}_{\text{vol}}\) values were lower than the median SSDE\({}_{\text{Dw}}\), whereas it exceeded the median SSDE\({}_{\text{Dw}}\) in all other age groups. The total area in the ROI (cm\({}^{2}\)) in the cross-sectional head images is presented as the mean \(\pm\) SD (minimum-maximum) for different age groups: 115.48 \(\pm\) 21.24 (81.95-168.18) cm\({}^{2}\) for the age group of 0 to 6 months, 160.77 \(\pm\) 20.10 (122.79-209.41) cm\({}^{2}\) for the age group of 6 months to 3 years, 174.78 \(\pm\) 13.85 (141.55-230.73) cm\({}^{2}\) for the age group of 3 to 6 years, 190.82 \(\pm\) 13.34 (160.25-216.65) cm\({}^{2}\) for the age group of 6 to 12 years, and 200.46 \(\pm\) 11.78 (175.54-216.65) cm\({}^{2}\) for the age group of 12 to 15 years. The mean \(\pm\) SD (minimum-maximum) of the conversion factor for CTDI\({}_{\text{vol}}\) to SSDE\({}_{\text{Dw}}\) for the CT head exams, as a function of the Dw for the different age groups, are as follows: 1.08 \(\pm\) 0.06 (0.95-1.19) for the age group of 0 to 6 months, 0.95 \(\pm\) 0.05 (0.86-1.05) for the age group of 6 months to 3 years, 0.92 \(\pm\) 0.03 (0.83-0.99) for the age group of 3 to 6 years, 0.89 \(\pm\) 0.03 (0.85-0.96) for the age group of 6 to 12 years, and 0.87 \(\pm\) 0.02 (0.82-0.93) for the age group of 12 to 15 years. The conversion factor and age showed a strong negative correlation (\(r=-0.70\)), which was significant (\(p<0.001\)). The linear analysis of the relationship between patient head size, Dw, and SSDE revealed a strong negative correlation. The R-squared values for the different age groups were as follows: 0.9986 for the age group of 0 to 6 months, 0.9989 for the age group of 6 months to 3 years, 0.9993 for the age group of 3 to 6 years, 0.9998 for the age group of 6 to 12 years, and 0.6475 for the age group of 12 to 15 years, all of which were statistically significant (\(p<0.001\)). Additionally, a strong negative correlation was observed between the conversion factor and Dw, with an R-squared value of 0.9975, which was statistically significant (\(p<0.001\)). Figure 2 shows a box plot of the mean CT numbers within the ROI (HU) across the five age groups. The median value for the 0-to-6-month age group was lower than that of the other age groups. The median value for the 6-month-to-3-year age group was slightly lower