National diagnostic reference levels have a lot of potential but a long way to go. A systematic review on the current status of adult diagnostic reference levels in head, chest and abdominopelvic Computed Tomography.

Head and body computed tomography (CT) is a routinely employed diagnostic tool for the detection and diagnosis of disease processes. With the chief focus of radiation dose reduction and improvements in CT scanners, radiation dose exposure still remains an ever-increasing concern. However, scanning protocol optimization relative to body weight and scanner manufacturer still lags behind Diagnostic Reference Levels (DRL) that are set on an international scale. The aim of this systematic review is to evaluate the current status of DRL over time on a global scale. A search was carried out in early 2019 using the Medline, PubMed, EMBASE, SCOPUS and manual databases. Reference lists of published articles were also assessed to identify further articles. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology was employed to evaluate articles for relevance. Articles were included if they assessed DRL in head, chest and abdominopelvic scans. The search resulted in 6079 articles, of which, 67 were included after a thorough screening process. The literature demonstrates a wide dose variation in reported head, chest and abdominopelvic DLP DRL ranging from 700-1359, 330-707, and 550-1486 mGy*cm, respectively. Where reported, CTDIvol DRL in the head, chest and abdominopelvic ranged from 30.4-85.5, 9-15, and 12.3-31 mGy*cm, respectively. The global means were shown to be slightly lower than the reported values in DLP and CTDIvol values for American College of Radiology and European Commission, respectively. This current review emphasizes the need for an international standardization for head and body DRL establishment methods, to provide a more comparable global measurement of dose variations across CT sites as well as regular monitoring in delivered radiation dose to patients.