National diagnostic reference levels: What they are, why we need them and what's next

Diagnostic reference levels (DRLs) are an optimisation tool for medical imaging procedures using ionising radiation. They give an indication of the expected radiation dose received by an average-sized patient undergoing a given imaging procedure. Comparison of typical (median) exposure levels for common imaging procedures with DRLs helps imaging facilities identify procedures that may be amenable to further optimisation. Undertaking comparisons with published DRLs is a requirement for medical imaging facilities under the Code for Radiation Protection in Medical Exposure and for their access to Medicare rebates under the Diagnostic Imaging Accreditation Scheme (DIAS). The Australian Radiation Protection and Nuclear Safety Agency has created the National Diagnostic Reference Level Service to facilitate the collection of data for the establishment of national DRLs in Australia and to assist imaging facilities in comparing their typical doses with the national DRLs. National DRLs have been established in computed tomography, nuclear medicine, and for image-guided and interventional procedures. DRLs must be subject to ongoing review and revision by the national authority to ensure they reflect current practice. This ongoing cycle of assessment and review helps to ensure that the ratio of benefit to risk for patients is maximised.