The concept of national reference doses was first introduced in the United Kingdom in 1980s,
after a national survey of doses from some common X-ray procedures [1].
The International Commission on Radiologic Protection (ICRP) introduced diagnostic reference levels in 1990 and further developed
the concept in publications 73,
105 and 135 [2].
The International Basic Safety Standards from 1996 defined "guidance level",
the term that has been replaced with "diagnostic reference level" (DRL) in the latest International Basic Safety Standards published in 2014 in the IAEA General Safety Requirement (GSR) Part 3 [3].
GSR Part 3 defines DRL as "a level used in medical imaging to indicate whether,
in routine conditions,
the dose to the patient or the amount of radiopharmaceuticals administered in a specified radiological procedure for medical imaging is unusually high or unusually low for that procedure." The concept of DRL applies to X ray medical imaging,
image guided interventional procedures and diagnostic nuclear medicine,
for which DRL is used to indicate the need for an investigation.
GSR Part 3 also requires periodic assessments to be performed of typical doses or activity of the radiopharmaceuticals administered in a medical facility.
"If comparison with established diagnostic reference levels shows that the typical doses or activity of the radiopharmaceuticals administered are either too high or unusually low,
a local review is to be initiated to ascertain whether protection and safety has been optimized and whether any corrective action is required [3].
GSR Part 3 defines the responsibilities for establishing and using DRLs as a tool for optimization of radiation protection of patients.
For the establishment of DRLs,
the government of each country shall ensure that "as a result of consultation between the health authority,
relevant professional bodies and the regulatory body,
a set of diagnostic reference levels is established for medical exposures incurred in medical imaging,
including image guided interventional procedures.
In setting such diagnostic reference levels,
account shall be taken of the need for adequate image quality.
Such diagnostic reference levels shall be based,
as far as possible,
on wide scale surveys or on published values that are appropriate for the local circumstances."
In a medical facility,
registrants and licensees shall ensure that periodic local assessments are performed of typical doses or activity of the radiopharmaceuticals administered for those radiological procedures for which DRLs have been established." If comparison with established diagnostic reference levels shows that the typical doses or activity of the radiopharmaceuticals administered are either too high or unusually low,
a local review is to be initiated to ascertain whether protection and safety has been optimized and whether any corrective action is required [3].
The IAEA has been supporting its Member States in implementing the requirements of the International Basic Safety Standard by a series of actions briefly described in this paper.