National Physical Laboratory

Diagnostic and mammographic X-ray dosemeters

NPL's diagnostic and mammographic calibration service is for ionisation chambers to be used intentionally as secondary standards or instruments required for measurement of the greatest accuracy. Calibration of either an ionisation chamber alone or of a complete instrument is available.

Service Delivery

NPL's accurate measurements of delivered patient radiation dose are traceable to national standards. These measurements, used in diagnostic examinations, ensure:

  • Effective, low doses are used;
  • Potential hazards in relation to regulation and Codes of Practice are identified.


  • Calibrated directly against the NPL air kerma primary standards.
  • X-ray qualities in accordance with BS IEC 61267:2006 Medical Diagnostic X-ray Equipment - radiation conditions for use in the determination of characteristics.
  • Air kerma rates in the range 5 mGy/hr to 50 mGy/hr.

Calibration Service Specification and Availability

Calibrations are normally carried out between October and December each year, and are undertaken with X-ray qualities in accordance with BS IEC 61267:2006 as follows:

Diagnostic and Mammographic Air Kerma X-ray Dosemeters


Technical Advice:
Martin Kelly
Tel: +44 20 8943 8502

Customer Measurement Services:
Radiation Dosimetry Team
Tel: +44 20 8943 8695

Last Updated: 9 Aug 2016
Created: 17 Apr 2007


Please note that the information will not be divulged to third parties, or used without your permission