# Monitoring Pediatric Head CT Scan Dose Levels:
## 3 Results and Discussion  
The scanner installed in the SSMC hospital is manufactured by Siemens (Siemens Healthineers, SOMATON machine model, Erlangen, Germany). This scanner is equipped with dedicated pediatric CT imaging including 70 KV scan modes and specific CARE Dose4D, a Siemens technology for automated exposure control. The scan acquisition parameters are presented in Table 1. The patient tube voltage for the children age groups considered in this study was between 80 kVp and 100 kVp for patients younger than 1 year. For the other age groups, this parameter was between 80 kVp and 120 kVp. The tube current-time product ranged from 67 mAs to as high as 534 mAs. The lower limit value of the tube current-time product for the smallest age group was higher than that of the other groups. Despite the higher lower limit value of the tube current-time product for theyoungst age group, the overall dose received by the patients was still within the safety standards, as we will see later. This suggests that in the CT scanner used in this study, appropriate radiation dose reduction strategies are implemented that optimize radiation doses for pediatric patients. Different percentages (25%, 50%, and 75%) of the patients were administered particular doses of CTDIVol, and DLPs were calculated from the data. Table 2 shows these results. As can be seen, 75% of the children below 1 year received 18.4 mGy of CTDIVol and 304 mGy-cm of DLP. These values increased, as expected, with older age groups. For example, for those aged 10 to 16 years, these doses reached 27.8 mGy and 568 mGy-cm. The increase in values for the CTDIVol and DLP with age in pediatric CT scans is likely due to the larger size of the older children and the need for higher radiation doses to penetrate more tissue. However, it is important to note that while larger pediatric patients may require higher radiation doses, efforts should still be directed toward minimizing radiation exposure as much as possible. An important observation is a large variation in the DLP dose quantities for the head CT scan for the age group \(<\) 1 year. The large variation in DLP doses for head CT scans in infants younger than one year of age can be attributed to several factors such as patient size and shape, scanner settings, imaging protocol, and patient motion. Infants have smaller heads and necks, making it challenging to position them correctly, and are more likely to move during the scan. The imaging protocol and scanner settings can be adjusted by the technologist, which can lead to differences in dosage. These factors highlight the importance of careful planning and optimization of CT protocols to minimize radiation doses for this vulnerable patient population. For the other age groups, the DLP values ranged between 92.3 mGy-cm and 341 mGy-cm. In the group of \(\geq\)1 y-\(<\) 5 y, the range was between 120 mGy-cm and 876 mGy-cm. The age group of \(\geq\)5 y-\(<\) 16 y had a range between 177 mGy-cm and 1300 mGy-cm, and for the age group of \(\geq\)10 y-\(<\) 16 y, the range was between 389 mGy-cm and 1119 mGy-cm. A similar variation was observed in the CTDIVol dose quantities for head CT scans for all the age groups. Variations in pediatric head CT imaging protocols, e.g., whether the protocols are based on one sequence or more, image \begin{table}
\begin{tabular}{c c c} \hline \hline \multicolumn{3}{c}{**Exposure Parameters**} \\ \hline
**Age Group** & **Tube Voltage** & **Tube Current-Time Product** \\  & **(kVp)** & **(mAs)** \\ \hline \(<\)1 year & 80–100 & 110–297 \\ \hline \(\geq\)1 y \(<\)5 y & 80–120 & 67–366 \\ \hline \(\geq\)5 y \(<\)10 y & 80–120 & 77–581 \\ \hline \(\geq\)10 y \(<\)16 y & 80–120 & 63–534 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Exposure parameters (tube voltage and tube current–time product) for the age groups considered in this study.