Diagnostic Reference Levels for Abdominal Computed Tomography Examinations in a South Eastern State, Nigeria
Background: The use of diagnostic reference levels has been shown to reduce the overall dose and the range of doses observed in clinical practice. Optimization of patient dose in computed tomography requires the application of examination-specific scan protocols tailored to patient age, size, region of body and clinical indication.
Objectives: To establish the computed tomography dose index (CTDI) and Dose-length product (DLP) for abdominal CT examinations in Anambra State and to ascertain the level of compliance of current practice with respect to the internationally established (DRLs) as well as the effective dose values for abdominal CT examinations.
Method: A total of 60 adult subjects presented for abdomen examinations from each of the four CT centers with a total of 240 subjects were surveyed for over a 6-month period. Data were obtained from a GE Brightspeed multidetector CT scanners, Toshiba Alexium and Siemens somaton perspective. The dose was derived from computed tomography dose index (CTDI vol), and dose length product (DLP) with the effective dose (E) calculated. Data were analyzed using SPSS version 20 software and 75th percentile of DLP and CTDIvol were adopted as a basis for DRLs.
Results: The 75th percentile values for CTDIvol and DLP were 24mGy and 962.8 mGy/cm for the abdomen. The calculated effective dose value is 14.4mSv.
Conclusion: Dose variations across CT centers have identified an urgent need for optimization to bring down center-specific and composite DRL in tandem with works done abroad
Keywords: Dose optimization, Computed Tomography, Diagnostic Reference Levels