Proposed national diagnostic reference levels for computed tomography examinations based on clinical indication, patient gender and size and the use of contrast in Lebanon

This study aims to propose national diagnostic reference levels (DRLs) for computed tomography (CT) scans performed on adult patients based on clinical indication (CI), patient gender and size and the use of contrast in Lebanon. The volume CT dose index (CTDIvol), size-specific dose estimate (SSDE) and dose length product (DLP) were collected between July 2017 and May 2022 from 14 Lebanese hospitals. The data were collected from at least 20 patients for 15 common group of CIs (GCIs) in the head, thorax, abdomen (AB), abdomen-pelvis (ABP) and thorax-abdomen-pelvis (TABP) regions. National DRLs were calculated for each GCIs, patient gender and size and depending on the use of contrast as the third quartile of the CT units' median values of CTDIvol, SSDE and DLP. The proposed national DRLs in term of CTDIvol (DLP) were 65, 15, 9, 9 and 13 mGy (1104, 483, 520, 442 and 611 mGy.cm), respectively, for Head/Hemorrhage, ABP/Appendicitis, AB/Abdominal pain, Thorax/Covid-19 and TABP/Trauma. The proposed national DRLs were higher than those from the literature pointing up the need for a dose optimization strategy to protect the patient from the harmful effects of radiation.