National indication-based diagnostic reference level values in computed tomography: Preliminary results from Ghana.

Abstract

This study was conducted to develop national indication-based DRL values for common indications of adult computed tomography (CT) examinations for clinical application in Ghana. The methodological approach recommended by the International Commission on Radiological Protection (ICRP), Publication 135, for the development of DRLs, was employed. Studies on CT infrastructure, common indications and quality control tests were first undertaken. A sample of 20 CT dose descriptor/quantity data sets were collected from each centre for each indication. Overall, 3960 data sets were collected for all identified common indications from 71.4% of the total CT scanners in Ghana (25/35). The data were collected from image folders reported and accepted by radiologists. The objective image quality was assessed through a signal to noise ratio (SNR) analysis prior to using the data and extracting DRL values. Clinical indications and their respective DRL values in terms of volume weighted CT dose index (CTDIvol) and dose length product (DLP) were cerebrovascular accident (CVA)/stroke (77mGy; 1313mGy.cm), head trauma/injury (76mGy; 1596mGy.cm), brain tumour/space occupying lesion (SOL) (77mGy; 2696mGy.cm), lung tumour/cancer (12mGy; 828mGy.cm) and chest lesion with chronic kidney disease (CKD) (13mGy; 467mGy.cm). Others were abdominopelvic lesion (17mGy; 1299mGy.cm), kidney stones (15mGy; 731mGy.cm), urothelial malignancy/CT-intravenous urogram (CT-IVU) (11mGy; 1449mGy.cm) and pulmonary embolism (PE) (14mGy; 942mGy.cm). National Indication-based DRL values developed in this study are recommended to be used to manage CT radiation dose in Ghana.