Does the Diagnostic Reference Level of Chest CT Scan Need to Be Updated in the Pandemic Situation?

Introduction: During the Covid-19 pandemic, CT scan has a significant role in screening and follow-up this disease. This study intended to assess the radiation effective dose (ED) and additional cancer risk (ACR) due to chest imaging and examine the differences in decision-making between different imaging centers to choose chest CT imaging protocols during the pandemic.Methods: This retrospective study assessed the ED of all chest imagings for Covid-19 during six months in four different hospitals in our country. Imaging parameters and dose area products (DLP) (mGy/cm2 ) were recorded. The EDs and ACRs from chest CT scans and chest x-ray (CXR) were calculated using an online calculator.Results: Thousand-six hundred patients were included in the study. The mean cumulative estimated dose due to chest CT and CXR was 4.065 mSv which might cause 2.62× 10-2 ACR. The mean cumulative ED in different hospitals was in the range of 1.96 to 9.51 mSv.Conclusions: The variety of mean EDs shows that different hospitals used different imaging protocols. Since there is no defined diagnostic reference level (DRL) in the pandemic situation, some centers use the routine protocols, and others try to reduce the dose but insufficiently.In pandemics such as Covid-19, when CT scan is used for screening or follow-up, DLPs can be significantly lower than normal situation. Therefore, international regularized organizations such as the international atomic energy agency (IAEA) or the international commission on radiological protection (IRCP) should provide new DRL ranges.