1. Introduction
Computed tomography (CT) is an effective diagnostic procedure used to image different body organs and diagnose pathologies. However, it is considered one of the most frequent and highest sources of ionizing radiation among diagnostic imaging modalities for patients undergoing these procedures and, consequently, for radiological staff [
1,
2,
3,
4].
The relationship between radiation dose and the response of body tissues (i.e., cancer risk) was introduced as an absolute or relative relationship. With the absolute relationship, the cancer risk of radiation is independent of the age of the exposed person (the same risk magnitude at any age), whereas with the relative relationship, the risk is dependent (children and elders at the highest radiation risk) [
5,
6].
Thus, it is essential to assess radiation dose and optimize these procedures, especially for pediatric patients. Young patients are more radiosensitive and have a longer life expectancy, which increases the probability of radiation-induced cancers [
7,
8,
9]. Therefore, minimizing ionizing radiation exposure is necessary to avoid its adverse effects while maintaining acceptable image quality [
10,
11,
12].
The amount of energy absorbed in the human body is significantly related to the type of radiation (e.g., X-rays, protons, and alpha particles). Thus, the radiation weighting factor for each type of radiation (W
R) was introduced to quantify the energy absorbed in the human body from each type of radiation. X-rays and gamma-rays were given the lowest W
R (i.e., W
R = 1). The concept of an organ or tissue weighting factor (W
T) was introduced to quantify the radiosensitivity (response of an organ or tissue to radiation) for each organ or tissue type [
13]. One of the commonly used methods to assess radiation dose is the effective dose (ED). It represents the absorbed radiation energy in the whole body, from homogeneous and uniform radiation, multiplied by a W
T for each organ or tissue [
14,
15]. ED can be assessed theoretically or experimentally. In addition, a valuable method that can be used to monitor radiation dose levels is the diagnostic reference levels (DRLs). DRLs were introduced in 1996 by the International Commission on Radiological Protection (ICRP), with guidelines updated in 2001 [
16,
17]. DRLs indicate when radiation doses are considered optimal. For CT procedures, DRL values are set at the 75th (local and national DRLs) or 50th (typical values for single facility DRLs) percentile of the distribution of the CT dose index (CTDI
vol) or dose length product (DLP) [
18,
19].
The European Commission of Radiation Protection reported in the European guidelines on diagnostic reference levels (2018) that DRLs for radiological examination procedures were not established in many countries. In addition, dose optimization for pediatric patients is a demanding subject. Thus, this is the first study conducted to establish DRLs for pediatric patients who underwent CT procedures in Madinah. The national DRLs can then be derived and established through the integration of local DRLs. Moreover, DRL values are not permanent values; they should be revised and updated regularly, for example, every 3–5 years or when new imaging techniques or technologies are introduced [
19,
20,
21].
This study aims to assess effective radiation doses (EDs) for pediatric computed tomography (CT) procedures in Madinah (single hospital), Saudi Arabia, and propose diagnostic reference levels (DRLs) for these procedures.
4. Discussion
CT diagnostic procedures are considered one of the highest sources of ionizing radiation, posing risks to both patients and medical personnel. Therefore, it is essential to assess radiation dose to reduce the effects of ionizing radiation while maintaining acceptable CT image quality for precise diagnoses.
A simple and straightforward method to assess radiation dose for CT procedures is to multiply the DLP by a CF to obtain the ED. This allows for estimating the possible risks of CT radiation and can take a step forward to optimize radiation exposure levels and minimize its risks.
The results for EDs and DRLs were computed and shown in
Table 2 and
Table 3. Then, the results were compared with the values for EDs and DRLs found in the literature, as shown in
Table 4,
Table 5 and
Table 6. In this study, the maximum ED values were found in head and abdominal CT procedures for patients aged <1 year, whereas the minimum values were found in chest CT procedures. The values of the CTDI
vol and DLP for head CT procedures were higher than the other CT procedures among all pediatric age groups.
The high EDs for head CT procedures were reported by Huda and Vance (2007) and Aw-Zoretic et al. (2014) [
40,
41] for patients aged <1 year compared to older or adult patients. These reports highlighted a concern for the importance of radiation dose optimization for young patients, as they are more radiosensitive and have a longer life expectancy, which increases the probability of radiation-induced cancers. In this study, the results of EDs for head CT procedures for patients aged < 5 years were higher than that reported by the USA (1) [
26], Malaysia [
27], and the USA (3), but the results for older age groups were comparable with these studies [
28].
The DRLs of the DLP for head CT procedures for patients aged <1 year were found to be higher than the DRLs mentioned in USA (2) [
29], European [
20], and German [
34] reports but lower than the Japanese DRLs [
33]. On the other hand, the DRLs of CTDI
vol appeared to be comparable with those reported in the previous studies.
Similarly, high EDs for abdomen CT procedures for patients aged < 5 years were noticed when they were compared with EDs reported by the USA (4), Turkey, and the USA (1). The DRLs of the DLP and the CTDI
vol for abdominal CT procedures for patients aged < 5 years were found to be lower than those reported in the international [
36] and Chinese [
37] DRL reports but higher than those reported in Franch DRLs [
35]. However, the difference could be related to the CT protocol setting (axial or helical scan), parameter settings, and type of the CT machine.
Thus, the results obtained in this study for EDs and DRLs were found to be the same, lower, or higher than the values found in the literature. Nevertheless, the results for abdominal and head EDs and DRLs, when compared with the values found in the literature, show the necessity for radiation dose optimization for patients aged <1 year. In addition, the assessed radiation dose and the proposed DRLs can be guidelines for the optimization of pediatric CT procedures.
Even though most of the assessed EDs and DRLs were found to be low or the same compared to the values found in the literature, radiation dose optimization should continue to reduce radiation dose received by pediatric patients undergoing CT procedures. This can be achieved by the optimization of EDs and establishment of DRLs for these procedures. Moreover, the revision of CT protocols and parameters is recommended. However, setting an optimal CT protocol with high image quality was reported as a demanding technique due to the variation in pediatric patients’ size [
42]. In addition, deep investigations could be valuable to find the effect of different pediatric genders on EDs and DRLs results.
There are some important caveats to the study that deserve mentioning. There were no age subgroups (e.g., for pediatric patients aged 1 to 12 months and 1 to 5 years) that reflected significant variations in pediatric patient size and weight within the same age group (i.e., the age categories used in this study), especially for the youngest age groups (<5 years old). This could affect the precision of the ED assessments for these age groups. However, the age group categories in this study were reported in the AAPM report no. 96 and ICRP publication 102 [
23,
24]. Nevertheless, it is suggested to add additional pediatric age group increments, such as months for newborns and years for children less than 5 years old. Additionally, different pediatric genders may need deeper investigation in future work to determine if the gender could affect the ED and DRL results. Finally, the risks associated with radiation doses were not calculated or estimated in this study. This could be performed as an extended future work to provide a more comprehensive understanding of the radiation risks for pediatric patients.
5. Conclusions
In this study, the results of EDs and DRLs from pediatric CT procedures indicated that ED and DRL values were the same, higher, or lower than the ED and DRL values found in the literature. The maximum ED values were found in abdominal and head CT procedures for patients aged <1 year, whereas the minimum values were found in chest CT procedures. The values of the CTDIvol and DLP for head CT procedures were higher than the other CT procedures among all pediatric age groups. Thus, ED and DRL optimization is required for abdominal and head CT procedures in pediatric patients aged <1 year.
The assessed radiation dose and the proposed DRLs can be guidelines for optimizing pediatric CT procedures. In addition, frequent updates on ED and DRL calculations for pediatric CT procedures will help monitor radiation doses and minimize radiation risks for patients undergoing these procedures.