Approaches to Establishing National Diagnostic Reference Levels for Computed Tomography: A Systematic Review

Abstract

Background: The international commission on radiation protection (ICRP) publican 135 recommends that Diagnostic Reference Levels (DRLs) should be tied to defined technical and patient parameters for the imaging task. Whereas for computed tomography (CT) examinations, DRLs are defined in terms of two established technical parameters namely, Volume-based Computed Tomography Dose Index (CTDIvol) and Dose Length Product (DLP), a debate has ensued as to whether patient size, age and weight or clinical indication should be used as patient parameters. The objective of diagnostic reference levels (DRLs) is to assist in the optimisation of radiation dose to the patients while maintaining diagnostic image quality. It is generally accepted that each country requires having national DRLs to guide the practice of radiography regarding dose optimization as a prerequisite to good radiation protection practice. Objective: This review aimed to establish commonly used approaches to establishing national diagnostic reference levels for computed tomography. Methods: A systematic literature search in databases containing leading journals in radiography, radiology and medical physics was performed aided by the use of carefully selected search terms that relate to CT and DRLs. The literature search was achieved by the use of the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) flow chart. A total of 109 studies were screened out of which 54 were excluded and 55 sought for retrieval. After further assessment for quality, 20 studies were included in this study for review. Key Findings: 95% of the studies in this review used CTDIvol and DLP as technical parameters indicating dose. 70% of the studies reviewed used patient size, age and weight while 30% used clinical indication as patient parameters. 30% of the reviewed articles did indicate that the surveys to establish NDRLs employed a retrospective approach, while 35% employed a prospective approach and 35% did ..