P2. Diagnostic reference levels for common CT examinations in the Radiology Department at the CMJAH

Abstract

Introduction Diagnostic reference levels (DRLs) are a form of investigation/monitoring level used as a simple test to identify situations where patient dose is unusually high and they apply to medical exposures, not to occupational and public exposures. If it is found that procedures are consistently causing the relevant DRLs to be exceeded, there should be a local review of procedures and the equipment in order to determine whether the imaging system and techniques have been adequately optimized. If not, measures aimed at reduction of doses should be taken. The purpose of this study was to establish DRLs by collecting radiation doses for the Head, Abdomen/Pelvis and Chest Computed Tomography (CT) examinations in adult patients, as the most frequently performed procedures, and then compare the results with the DRLs in other countries. The data were collected from studies performed on the Philips Brilliance 64-slice CT scanner installed in the Radiology Department. Materials and methods The CTDIvol and the DLP used in this study are average values which are displayed on the monitor of the CT scanner. These DRLs are based on the sample of 308 patients of mass 75 ± 15 kg for both genders. Results The DRLs found using CTDIvol (mGy) and DLP (mGy·cm) were for head (32.0 and 774.7), abdomen/pelvis (13.3 and 742.0) and Chest (11.9 and 521.8). These values are lower than the DRLs published by the EU (2000), UK (2003), EU (2004) and IAEA (2006) except for the abdomen/pelvis which was found to be 2.5% above the EU (2004) data. Conclusion The findings from this study are recommended for use as baseline local DRLs in the Radiology department at CMJAH for this CT scanner. CT protocol optimization is necessary for the abdomen/pelvic examinations. The other CT scanners in the department should also be studied and compared.