ESR News July 2014

Diagnostic Reference Levels: An optimisation tool for managing
patient radiation doses

John Damilakis, Professor of Medical Physics

The concept of Diagnostic Reference Levels (DRLs) has been introduced to indicate unusually high or low patient radiation doses from medical imaging examinations and procedures. In 1999 the European Commission (EC) issued the Radiation Protection 109 (RP 109) publication on „Guidance on diagnostic reference levels DRLs for medical exposure“ (1). This document highlights the importance of establishing DRLs for high-dose medical examinations, in particular computed tomography and interventional radiology procedures. The newly published ‘Euratom BSS’ (2) states that ‘Diagnostic reference levels means dose levels in medical radiodiagnostic or interventional radiology practices, or, in the case of radio-pharmaceuticals, levels of activity, for typical examinations for groups of standard-sized patients or standard phantoms for broadly defined types of equipment’.  Moreover, the BSS states that ‘Member States shall ensure the establishment, regular review and use of diagnostic reference levels for radiodiagnostic examinations, having regard to the recommended European diagnostic reference levels where available, and when appropriate, for interventional radiology procedures, and the availability of guidance for this purpose’. A common approach for setting DRLs has been the use of the 75th percentile (third quartile) of the spread of the median doses of common protocols from a survey for groups of standardized patients or phantoms.

There is little information on DRLs for paediatric examinations and procedures. The main reasons for this lack of information are listed below:

  • The number of examinations carried out in children is lower compared to adults
  • Data need to be categorised into subgroups of age, weight, body size, etc
  • Difficulties in conducting patient dose surveys


There is a need to establish DRLs for radiological examinations and procedures where DRLs are not available, consolidate available information, and provide guidance on what actions are needed in using DRLs to further enhance radiation protection of children. The ‘European DRLs for Paediatric Imaging’ project (abbreviation: PiDRL) is a new EC project which aims to a) develop a methodology for establishing and using DRLs for paediatric medical imaging and b) update and extend the European DRLs to cover as many procedures as possible. The professional organisations involved include the ESR as coordinator as well as the European Federation of Organisations in Medical Physics (EFOMP), the European Federation of Radiographer Societies (EFRS), and the European Society of Paediatric Radiology (ESPR), covering the key European stakeholders and professional groups with relevance to radiation protection of paediatric patients. More information about this project can be found here.

1. EC, RP 109. Guidance on diagnostic reference levels DRLs for medical exposure. Directorate-General Environment, Luxembourg.
2. Council of the European Union. (2013). Council Directive 2013/59/Euratom laying down basic safety standards for protection against the dangers arising from exposure to ionising radiation, and repealing Directives 89/618/Euratom, 90/641/Euratom, 96/29/Euratom, 97/43/Euratom and 2003/122/Euratom. Official Journal L-13 of 17.01.2014.