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Home Publications Radiation NRPB Archive Miscellaneous NRPB Reports ›  National Protocol for Patient Dose Measurements in Diagnostic Radiology

National Protocol for Patient Dose Measurements in Diagnostic Radiology


Dosimetry Working Party of the Institute of Physical Sciences in Medicine

comprising representatives from

  • Institute of Physical Sciences in Medicine (IPSM)
  • National Radiological Protection Board (NRPB)
  • College of Radiographers (CoR)


The Dosimetry Working Party was set up by the Diagnostic Radiology Topic Group of IPSM in 1990 to supervise and report on a number of national and international projects concerned with radiation dosimetry in diagnostic radiology. One of these projects, following the recommendations of a joint report by the Royal College of Radiologists and NRPB on patient dose reduction (Doc. NRPB, 1 (3), 1990), was to draw up national protocols for the routine measurement of patient doses as part of quality assurance programmes in radiology departments. This document was published by NRPB to fulfil this objective.

The potential for reducing the radiation dose to the population from medical x-ray examinations is well established and indeed the requirement to deliver the lowest possible dose consistent with the clinical purpose of the examination is formalised in UK legislation. Presently, however, there are very few diagnostic x-ray facilities where specific information is available on the doses that they deliver to their patients.

This protocol sets out nationally agreed methods for monitoring patient doses from routine x-ray examinations that can be easily carried out by radiographers with advice and assistance from medical physicists. It provides guideline reference doses, that are in line with current national and European practice, against which individual x-ray facilities can compare their performance. These measurements and comparisons will greatly improve confidence in identifying those areas where effort can be most efficiently directed towards complying with the legal requirements for minimising patient dose. They will improve the quality of information available to health service managers and clinical directors of radiology departments for assessing both diagnostic procedures and priorities for expenditure on new imaging equipment.

Radiation Protection Advisers are encouraged in this protocol to participate in a system for the national collation of patient dose data so that the impact of patient protection measures on diagnostic radiology in the UK can be assessed centrally and guideline reference doses periodically revised. Finally, since it is well recognised that there are some circumstances in which over-zealous reductions in patient dose can have deleterious effects on image quality, simple methods for monitoring image quality are outlined.

The recommended methods of patient dose measurement are suitable for use in most types of conventional radiographic or fluoroscopic x-ray examination, although a preferred selection of types of radiograph and examination is given. The methods are not suitable for mammography or computed tomography for which appropriate dosimetry techniques are described elsewhere.


Single copies are available on request free of charge  Order

PDF download:

National protocol for patient dose measurements in diagnostic radiology (PDF, 4.5 MB)  Please note that the first two pages of this document form the cover.


Last reviewed: 14 November 2013