H. Khajmi et al.: Radioprotection 2025, 60( 1), 44 – 49 45
studies published in the Kingdom have described the DRLs for CT scanners by province and by individual hospitals( El Fahssi et al., 2024; Semghouli et al., 2024; Nhila et al., 2024; Tahiri et al., 2024), indicating that CT scanners are subject to regular upkeep. In addition, numerous works conducted in the nation( Andaloussi et al., 2021; Tahiri et al., 2022; Amaoui et al., 2023; Housni et al., 2023) have reported the theoretical understanding of radiation protection by radiologists, technologists, and medical physicists.
The DRL is crucial information for identifying outlier doses, especially in high-dose facilities, allowing us to suggest better radiation protection measures and lessen the dose load for CT examination patients. The results of this research will help identify practices that need immediate action to reduce the risk of radiation for patients undergoing CT exams in Marrakech.
According to ICRP( 2011) the present study aimed at defining local DRLs for adult CT procedures at the Mohammed VI University Hospital Center in Marrakech( Med VI UHC)( Morocco) and to evaluate it against previous international research( Smith-Bindman et al., 2015; Kanda et al., 2021; Zewdu et al., 2021; Li Z et al., 2020; Bashier et al., 2018; Shrimpton et al., 2014; Roch et al., 2018).
2 Materials and methods
The radiology departments of Arrazi Hospital of Marrakech, Morocco’ s Med VI UHC, served as the study’ s locations. With a bed capacity of 1548 and four scanners, Med VI UHC is one of Morocco’ s four largest academic, scientific, and medical facilities. The centre offers both general and specialty services to a population of 8055610. The number of conventional radiographs and digital images achieved in 2022 were 85103 and 65440, respectively.
Retrospective obtaining data was conducted for diagnostic CT scan collected in the period between December and May 2023 at the Arrazi Hospital facility associated with the Med VI UHC of Marrakech for routine CT examinations. The CT procedures were performed with Siemens Somatom Sensation 16, installed in 2008, periodically well maintained, and equipped with intensity modulation and iterative reconstruction. Demographic information( gender), CT exposure parameters( tube voltage( kV), tube current time-product( mAs), pitch, and CT dose quantity( CTDI vol, DLP) for adult patients between the ages of 18 and 80 years underwent routine CT scans in the radiology department were all gathered. The acquisition variables and dose quantities were directly taken from the DICOM structured dose reporting system. Head, chest-abdomen-pelvis( CAP), chest, and abdomen procedures were the routine exams considered in this investigation. The choice of these examinations was due to their high frequencies. No selection of weight, height, and other scan parameters was performed in this study. We selected the dosimetric data for each anatomical location with and without contrast injection. For all CT tests considered( Tab. 1), helical scanning type was performed.
2.1 Patient sampling
We proposed to assess and compare the radiation doses delivered to 640 patients of both sexes at the Arrazi Hospital of the Med VI UHC in Marrakech during the study period December and May 2023. In order to create our DRLs according to ICRP( 2011), we have gathered dosimetry numbers from more than 30 CT scans per anatomical area with and without contrast. Table 2 summarises the statistics obtained.
2.2 Statistical analysis
The data was analysed using statistical software from IBM SPSS version 26. For exam, the values for the 75 th percentile were determined. The minimum and maximum levels of voltage( kV) and intensity( mAs), as well as the mean, 50 th and 75 th percentiles of the dose metric distribution, were calculated as the DRL( ICRP, 2011). The results were examined using descriptive statistics. The 75 th percentiles of the measurements were compared with the DRLs in studies that were published on a number of continents( Smith-Bindman et al., 2015; Kanda et al., 2021; Zewdu et al., 2021; Li Z et al., 2020; Bashier et al., 2018; Shrimpton et al., 2014; Roch et al., 2018) and ICRP( 2017). These numbers, which are the first exclusive to the Med VI UHC’ s Arrazi Hospital, were gathered for the CT scan diagnostic reference levels. The findings of this study will govern future research on dosage.
3 Results and discussion
We obtained the dosage information from 640 CT exams. Abdominal CT accounts for 28 %( n = 179) of scans, followed by head( 26 %)( n = 166), CAP( 24 %)( n = 155), and chest( 22 %)( n = 140). Table 1 shows the distribution of the tube voltage used for adults CT. For all CT procedures, the tube voltage used for head, CAP, chest and abdominal scans ranges from 120 kV to 140 kV. The tube current fluctuated similarly, ranging from 224 mAs to 450 mAs, 45 mAs to 339 mAs, 48 mAs to 246 mAs, 71 mAs to 361 mAs, and from 71 mAs to 361 mAs. We notice that, the majority of CT exams are performed with a slice thickness of 5 mm, although the pitch for all CT acquisitions under review range from 0.55 to 1.5. The CTDI vol( mGy) and DLP( mGy. cm) quantities obtained in this investigation for all CT procedures are shown in Table 2 as the lowest, mean, maximum, 50th, and 75th results.
For a CT of the head, the DLP varies from 1281 mGy. cm to 1724 mGy. cm, with a mean of 1422 mGy. cm, while the CTDI vol varied from 34 mGy to 40 mGy, with a mean of 38 mGy, the CTDI vol and DLP at the 75th percentiles are 40 mGy and 1445 mGy. cm, respectively. Figure 1 shows the frequency distribution of DLP( mGy. cm) of the head CT. It is clear that a minor group of patients have a higher DPL value on head CT. This could mean that, in some cases, a different protocol is used.
The comparison between our DRL and various countries proposed standards are shown in Table 2. Except for research reported by Sudan in 2018( Bashier et al., 2018) and Ethiopia in 2021( Zewdu et al., 2021), the DRL of our CTDI vol in this paper is lower than all numbers reported internationally. However, it was discovered that the established DLP at the head CT’ s 75th percentile was superior to all of the DRL stated in worldwide reference dosages. One possible explanation for these high dosimetric situations might be the usage of mAs and