Establishment of diagnostic reference levels for common multi-detector computed tomography examinations in Iran

In order to establish diagnostic reference levels (DRLs) for multi-detector computed tomography (MDCT), four routine CT examinations were identified and a computer program was developed to collect data from 19 MDCT scanners in Iran. Mean values of Volume computed tomography dose index (CTDIvol) and dose-length product (DLP) in each site were calculated and the DRLs were defined as the 75th percentile of the distribution of the CTDIvol/DLP values for each examination. In terms of DLP, the DRLs of adult age group are 700, 290, 330, and 550 mGy cm for the Brain, Sinus, Chest, and Abdomen and Pelvis protocols, respectively. Although DRLs of this study are comparable to other international DRLs and in most cases are less than the international reference values, the great extent of dose distributions indicates that the CT imaging procedures in Iran should be optimized by applying diagnostic reference levels in order to decrease the radiation dose to patient undergoing CT examination.