298 A. Boulanouar et al.: Radioprotection 2025, 60( 4), 297 – 305
Table 1. Clinical indications selected in the MCH. CT examinations
Head Chest Abdomen-pelvis Chest-abdomen-pelvis
Clinical indications
Tumor / mass, cellulitis, trauma / haemorrhage, hydrocephalus, convulsive crisis
Bronchiectasis / bronchitis, pneumonia, congenital malformation Ileus, abdominal pain, adrenal neuroblastoma Infection / inflammation workup, tumor extension, tumor control
Moreover, multiple European studies have analyzed children’ s exposure as a function of CI in paediatric CT in Italy( Granata et al., 2015), Finland( Järvinen et al., 2015), Switzerland( Wagner et al., 2018), and France( Célier et al., 2020).
In Africa, studies by Joseph Zira( Joseph Zira et al., 2021), Samuel( Samuel et al., 2021), and Tchaou( Tchaou et al., 2016) aimed to establish DRL CI for paediatric head CT scans. In contrast, some Moroccan publications on diagnostic reference levels in paediatric CT focus specifically on the anatomical areas and age ranges of children( Benmessaoud et al., 2020; Semghouli et al., 2022; Benmessaoud et al., 2023; Khajmi et al., 2023). Nevertheless, Morocco had not previously conducted a survey of diagnostic reference levels based on clinical indications in paediatric CT.
This search aims to specify, for the first time, diagnostic reference levels per CI in paediatric CT at the Marrakech University Hospital Centre. We also seek to identify variations in these DRLs and compare them with international standards for each group of children studied.
2 Methodology
The study was conducted between April 2023 and July 2024 at the Med VI University Hospital of Marrakech’ s. All CT examinations were performed using a 16-slice Siemens Somatom Emotion CT scanner, which has been in service since 2008 and is equipped with automatic tube current modulation( CARE Dose 4D). This equipment is regularly maintained to ensure it remains up to date. The Ethics and Health Research Committee of the hospital approved the study. Children were divided into three age groups: 1 – 5 years, 5 – 10 years, and 10 – 15 years, in accordance with European guidelines on paediatric diagnostic reference levels( Granata et al., 2019). The investigation included four anatomical regions: head, chest, abdomen-pelvis, and chest-abdomen-pelvis CTs. Fourteen clinical indications were selected, as detailed in Table 1. These indications were favored due to their prevalence in the department. For each examination, we collected various CT acquisition parameters, including the exam indication, age and sex of the child, tube current( mAs), tube voltage( kV), use of contrast medium, number of scans, scan mode and length, and pitch. Using our Picture Archiving and Communication System( PACS), we recorded the CTDI vol( mGy) and DLP( mGy. cm). The children’ s weight was not recorded at the time of the examination, so categorization by weight was not applicable.
2.1 Statistical analysis and testing
Descriptive statistics, including frequency, mean, quartiles, maximum, and minimum values, were computed using IBM
SPSS Statistics software( v26). The DRLs for specific age groups of children and CI were assessed based on the median and third quartile of the CTDI vol and DLP values( Vañó et al., 2017).
We employed the non-parametric Kruskal-Wallis test to assess variations in Diagnostic Reference Levels between different indications within the same anatomical region for specific age groups. The choice of this test was guided by the non-normal distribution of the CTDI vol and DLP values, making the Kruskal-Wallis test appropriate for comparing the medians of these variables among several independent groups. All analyses were conducted with a significance level set below 0.01. Subsequently, we compared the DRLs by indication for each age group, including the 75th percentiles of CTDI vol and DLP, against those reported by other researchers in Europe and Africa( Järvinen et al., 2015; Granata et al., 2015; Wagner et al., 2018; Célier et al., 2020; Joseph Zira et al., 2021). The dose distributions for the 25 th, 50 th, and 75 th percentiles of CTDI vol( mGy) and DLP( mGy. cm) as a function of age and CI for the head CT scans studied are illustrated in Figures 1 and 2.
3 Results and discussions
Radiation dose data from 1730 paediatric CT exams involving children were gathered. Among the participants, 60 %( n = 1038) were male and 40 %( n = 692) were female. The age distribution was as follows: 34.3 % of the children were between one and five years old, 32 % were aged five to ten years, and 31.4 % were between ten and fifteen years old. Head CT exams were the most common, accounting for 42.2 % of the total, with trauma and hemorrhage being the primary indications at 12 %. Other types of scans included chest CT scans( 19.5 %), CAP CT scans( 19.8 %), and abdomen-pelvis CT scans( 18.5 %). The main clinical indications for paediatric CT scans of the chest, CAP, and abdomen-pelvis included infectious, inflammatory, malformation, and tumor conditions, each representing an average of 6.4 % of the total indications.
Overall, there is a noticeable difference in CT acquisition parameters depending on the indications reviewed, as shown in Tables 2 and 3. For all the CI examined, the tube voltage was set at 110 kV for children under 5 years and ranged from 110 to 130 kV for children over 5 years. We used intensity modulation at 83 % for head CT scans and at 100 % for chest, CAP, and abdomen-pelvis CT scans in order to adjust the mAs load based on the child’ s body size. We prefer to perform 94 % of head CT scans and all other tests in helical mode for CT acquisition.
Moreover, within each age group, there are variations in practices regarding the number of series, scan lengths based on indications, and the timing of contrast product injections for