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Home Publications Radiation NRPB Archive Documents of the NRPB ›  Documents of the NRPB: Volume 10, No. 1

Documents of the NRPB: Volume 10, No. 1

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Publication date: 1999

ISBN: 0-85951-425-0



Guidelines on Patient Dose to Promote the Optimisation of Protection for Diagnostic Medical Exposures: Report of an Advisory Group on Ionising Radiation


Summary of recommendations

Please note that the paragraph numbering from the full published document has been retained but that the references cited have not been included here and a number of minor editorial changes have been made.


  1. All departments of diagnostic imaging should have in place a mechanism for the regular measurement of patient dose. Indeed, this will be a statutory requirement under implementation of the recent EC Directive. Such dose measurements should be collated in a national database in order to allow monitoring of practice and periodic revision of advice on patient protection.
  2. Agencies considering the introduction of departmental accreditation should include compliance with dose guidelines for a core set of examinations; these might include, for example, lumbar spine, abdomen, barium enema, CT (computed tomography) of the head, dental panoramic radiography and mammography in adults, and skull, pelvis and chest radiography on patients aged 5 years.
  3. Reference doses should remain the priority target for all departments in which typical doses are above current reference dose values, and their use should be extended to other areas of diagnostic investigation.
  4. Achievable doses based on operational and technological factors should be gradually introduced to supplant reference doses so as to encourage departments already below current reference dose values to optimise patient protection.

Conventional radiography

  1. Achievable doses should be used as a supplement to the existing reference dose values of entrance surface dose per radiograph when departments are assessing the results of local dose surveys conducted for the purposes of reviewing patient protection.
  2. Existing national reference dose values should be reset periodically in consultation with appropriate bodies. Further national reviews of radiographic practice should be conducted in order to extend both reference and achievable doses so as to continue to promote the optimisation of patient protection.


  1. All mammography systems should have regular measurements of MGD S (mean glandular dose for a standard breast model) on a 6 monthly basis; those involved in population screening should have daily monitoring of the radiographic exposure (mA s) setting required for a standard phantom (such as 40 mm thickness of polymethylmethacrylate, PMMA).
  2. All mammography systems with values of MGD S above 3 mGy should be subject to an immediate review of practice in order to justify their continued operation.
  3. Measurement of the doses to sample populations of women undergoing mammography should be introduced.
  4. When mammography equipment is replaced, consideration should be given to the selection of those machines capable of using larger (24 ?? 30 cm) cassettes.

Dental radiography

  1. It has previously been recommended that all dental x-ray sets should be assessed at least once in every 3 years. The Advisory Group now recommends this should be done annually.
  2. All dentists should employ a system of quality assurance to ensure that radiographic images are consistently of a high standard.
  3. Reference doses should be established in collaboration with appropriate professional bodies on the basis of published dose data from wide-scale surveys of dental practice.
  4. The concept of dose-width product should be further developed so as to provide a practical means for monitoring patient exposure during panoramic radiography.
  5. Achievable doses should be developed on the basis of the lowest exposure factors that produce acceptable diagnostic images, following recommendations on simple, cost-effective changes in radiographic technique.

Fluoroscopic examinations

  1. The present national reference dose values of dose-area product for common fluoroscopic procedures are unlikely to promote further improvements in current dosimetric performance and, accordingly, they should be revised in collaboration with professional bodies so as to help identify potentially unacceptable practice.
  2. Further advice should be developed concerning the establishment of achievable doses for fluoroscopic procedures on the basis of recommendations on practice.
  3. Methods should be developed for assessing the dose rate at the entrance surface of the patient and for the collection of such data during common fluoroscopic procedures.

Angiographic and complex interventional examinations

  1. All departments conducting angiographic and complex interventional examinations should undertake dose-area product monitoring.
  2. Methods should be developed for assessing the dose rate at the entrance surface of the patient and for the collection of such data during the more common procedures that involve prolonged fluoroscopy.
  3. In view of the significant potential for damage to skin, methods should be developed to allow the reliable estimation of absorbed dose to skin from complex radiological procedures.
  4. There should be central collation of dose-area product data from local patient dose surveys of angiography and interventional procedures in order to allow the establishment of national reference dose values.
  5. It is too early at present to address the concept of achievable doses for angiographic and interventional procedures owing to the complexity of techniques employed.

Computed tomography

  1. Further wide-scale review of dosimetric practice in CT is required in order to assess the suitability for promoting patient protection in the UK of both the dose descriptors and the initial reference dose values proposed by the EC on the basis of limited data.
  2. Monitoring of national practice in CT would be facilitated by the introduction of a national dosimetry protocol for CT and the central collation of local survey data, in parallel with the system in successful operation for conventional x-ray examinations.
  3. Consideration should be given to the feasibility of establishing achievable doses on the basis of general recommendations for CT procedures.

Paediatric examinations

  1. Further wide-scale review of dosimetric practice in paediatric radiology is required in order to assess the suitability of the initial reference dose values proposed by the EC for promoting patient protection in the UK.
  2. Consideration should be given to the feasibility of establishing achievable doses on the basis of general recommendations for paediatric procedures.

Nuclear medicine

  1. A more formal system of audit is required in order to monitor effectively national practice in diagnostic nuclear medicine.
  2. The Administration of Radioactive Substances Advisory Committee (ARSAC) should continue to review and update on a regular basis the appropriateness of the recommended DRLs (diagnostic reference levels) as an essential element of the optimisation of protection for patients undergoing diagnostic nuclear medicine procedures.
  3. Further consideration should be given to the potential role of achievable doses in relation to diagnostic nuclear medicine procedures.


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Last reviewed: 1 August 2013