Paul C. Shrimpton PhD, Presenter: Nothing to Disclose

David Hart PhD, Abstract Co-Author: Nothing to Disclose

Review trends in UK national diagnostic reference levels (DRLs) for x-ray examinations since the 1980s.

National DRLs for some common x-ray examinations were first suggested for the UK in 1989 following a previous national survey that demonstrated wide variations in practice between hospitals for similar procedures. These reference values were set pragmatically at the third quartiles of the distributions of mean values for each x-ray room of the practical dose quantities entrance surface dose (ESD) and dose-area product (DAP), in order to promote improvements in patient protection. Since 1992, the results of local patient dose surveys following a nationally agreed protocol have been voluntarily submitted to the Health Protection Agency in support of periodic review and updates on national trends and DRLs for 1995, 2000 and 2005. National DRLs for computed tomography (CT) were first published in 1999, following a UK survey in 1991 and the subsequent development of the practical monitoring quantities: volume CT dose index (CTDIVol) and dose-length product (DLP). Reference levels for CT were updated following a second UK survey in 2003.

The 2005 UK national DRLs for conventional x-ray examinations were typically lower by a factor of 2 for adults relative to 1995 and 1.3 for children relative to 2000, reflecting significant improvements in patient protection. In contrast, national reference doses for CT have typically fallen by only 10-40% between the national surveys for 1991 and 2003.

The concept of DRLs is now firmly established and widely implemented as a useful tool for promoting patient protection. In our experience, their informed application in the UK over the last 20 years has provided a practical focus for the management of patient dose and, as part of a coherent framework for patient protection, has facilitated significant reduction of unnecessary patient exposures.

This study highlights the rise over the last 20 years in the use of DRLs as a practical tool for promoting patient protection and the fall in national levels set for the UK following periodic reviews.

Shrimpton, P, Hart, D, The Rise and Fall of National Diagnostic Reference Levels in the UK: A 20- year Review.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11034279.html