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DRL for abdomen and thorax CT scan examinations in northern Nigeria , utilizing research for this region and comparing to global values . The results for the chest DRLs are 17.25 mGy for CTDI vol and 735 mGy cm for DLP , while the results for the abdomen are 19.25 mGy for CTDI vol and 1670.75 mGy cm for DLP .
In addition , DRLs for specific radiological examinations are established through studies . ( Dambele et al ., 2021 ) established DRLs for bone scintigraphy , whereas ( Salama et al ., 2017 ) conducted a research to establish a national diagnostic reference levels ( DRLs ) for computed tomography in Egypt . Comparing the Egypt DRL to a study in the UK , in their study , it was noted that the CTDI vol values for brain were approximately half that of the UK study . In conclusion , optimizing medical imaging is crucial for improving patient outcomes and preventing unnecessary radiation exposure ( Karim et al ., 2016a ; Muhammad et al ., 2022 ). Nigeria still requires extensive nationwide dose surveys in order to establish a national reference dose that will be followed in the future to ensure that patients receive the optimal radiation dose while maintaining image quality in medical imaging . One notable example of monitoring the DRL of computed tomography is evident in France , as well as in other countries ( Benamar et al ., 2023 ; Habib Geryes et al ., 2019 ; Hakme et al ., 2023 ). Good regulatory guidelines , additional training , and constant encouragement from the healthcare system to its personnel are required to increase the use of DRLs in Nigeria .
1.1 CT scan services in Sokoto state , Nigeria
To address the requirements of its population of over five million , the Sokoto State Government has established an Advanced Medical Diagnostics Centre to provide medical diagnostic services . The ancient city of Sokoto , situated in northern Nigeria , has two CT scan machines , one of which is situated at Usmanu Danfodiyo University Teaching Hospital ( UDUTH ) and the other at the Sokoto State Advanced Medical Diagnostic Center ( SSAMDC ). Unfortunately , the scanning machine in UDUTH is currently not functioning due to maintenance . Therefore , both public and private healthcare facilities in the state are heavily dependent on SSAMDC for CT scans .
2 Methodology
The SSAMDC Research Ethics Committee approved this retrospective study , with the ethical number SSREC / ID- 0091-22 , and no consent was required . All data was taken from the Picture Archiving and Communication System ( PACS ) system of 16 multi-slice CT scan ( CT Revolution , GE Healthcare , USA ). The scanner able to reconstruct 16 slices , each measuring either 0.63 mm or 1.25 mm in rotation . Regarded as state-of-the-art in Nigeria , the upgraded version of GE ’ s Light Speed CT series produces high-resolution 3D images which are better than other single slice CT scans . The data was collected from June 2021 to June 2023 . This research observed and evaluated the results of 190 patients .
2.1 CT dosimetry
CTDI ( measured in mGy ) is a standard measure used to compare the radiation dose output of different CT scanners . It is important to note that the CTDI value does not represent the actual dose to the patient , as they are neither cylindrical nor made of plastic . Two useful types of CTDI are CTDI w and CTDI vol . CTDI w is the weighted average of CTDI 100 measurements taken at two locations in a given phantom , one central and one peripheral , and mathematically expressed as
CTDI w ¼ 1 3 CTDI c þ 2
3 CTDI p :
CTDI vol is a measure of the dose for a scan protocol that takes into account the radiation dose profile from successive rotations of the X-ray source , including any gaps and overlaps . Mathematically , it is expressed as :
CTDI vol ¼ CTDI W pitch :
The dose-length product ( DLP ) is ultimately determined and provided by the console , taking into account the duration of the scan to calculate the total dose output . The DLP represents the entire dose absorbed by a phantom over the course of a scan . DLP , measured in milligray-centimeter ( mGy cm ), is advantageous for evaluating exam dose if the scan lengths are equal . This is mathematically expressed as :
DLP ¼ CTDI vol Scan length :
2.2 Data collection
We collected data from 190 cases to conduct our research , which included essential parameters such as effective tube current ( mAs ), tube voltage ( kVp ), exposure time ( s ), table feed ( TF ), pitch factor , scan range , and slice thickness . To acquire this information , we accessed the Digital Imaging and Communications in Medicine ( DICOM ) system of the hospital and obtained data regarding CTDI vol and DLP from the Picture Archiving Communication System ( PACS ) console , specifically for CT brain , CT thorax , and CT abdominal-pelvis examinations .
2.3 Statistical analysis
All the data related to scans , patient details and dose reports , was taken from the console and organized in a Microsoft Excel spreadsheet for further analysis . Boxplots were generated to visually display the median and third quartile of the CTDI vol and DLP values , which had been categorized according to anatomical regions and protocols , in order to assess the data and gain a clear understanding of the central tendency and distribution of the dataset . Furthermore , a student ’ s t-test was conducted to compare the means between groups and determine any statistically significant differences .