Michael Onoriode Akpochafor, Akintayo Daniel Omojola, Samuel Olaolu Adeneye, Victor Ekpo, Nusirat Adeola Adedewe, Aderonke Rashidat Adedokun, Dare Joseph Adewa, Moses Adebayo Aweda, Mary-Ann Etim Ekpo


Background: The use of computed tomography (CT) has further taken imaging a step forward but at higher dose to the patient. This has made relevant bodies to create dose reference level (DRL) as an investigational tool to identify unusually high radiation dose associated with the use of CTs. Aims and Objectives: This study intends to verify the current state of dose level of Volume CT Dose Index (CTDIvol) and Dose Length Product (DLP) for common CT examinations in South-West Nigeria, it also seek to compare differences for non-contrast and contrast examination and to compare and correlate its findings with International and national DRL for CTDIvol and DLP at 50th and 75th percentile. Materials and Methods: The study used 13 CT units which represent over 60% of functional CT facilities across Lagos. All scanners were multi-detector CT (MDCT) technology, with 2 to 128 slices with four different vendor: General Electric, Toshiba, Siemens and Philips. More than half of the CT used were 16-slice scanners. This retrospective study collected data from 702 male (317 non-contrast and 385 contrast agent) and 937 female (403 non-contrast and 534 contrast agent) respectively. Results: There was no difference in mean age, CTDIvol and DLP for non-contrast and contrast examinations for the 3 body regions. There was no difference in CT dose outputs (CTDIvol and DLP) with media at 50th (P = 0.956) and 75th (P = 0.963) percentile. Comparison of CTDIvol and DLP at 75th percentile for the 3 body region for non-contrast agent between this study and other studies were not statistically different. However, significant difference in DLP was seen in Kenya and Nigeria (P = 0.028 and P = 0.039).Comparison of CTDIvol at 75th percentile with contrast agent between this study and USA was different (P = 0.038), however, there was no difference in CTDIvol and DLP between this study and United Kingdom, Ireland and European Commission. Conclusion: CTDIvol and DLP were lower compared to other studies. CTDIvol and DLP in this study was in line with other studies for non-contrast examinations at 75th percentile.

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