X-ray radiation doses fall continuously

The amount of radiation to which patients are exposed when they use medical X ray machine is continuing to fall, according to the Health Protection Agency's latest five-yearly review of the National Patient Dose Database.

      There has been an average reduction in dose over the last five years in routine x-ray examinations of between 10 to 20%. This is mainly due to the ever increasing sensitivity of medical X ray machine. There is also far greater awareness of exposure levels in patient doses since the introduction of national reference doses in the early 1990s. This degree of awareness needs to be maintained, particularly in relation to digital radiography systems which are increasingly being introduced.

      The National Patient Dose Database was established in 1992 to collate the doses received by patients during routine x-ray examinations in hospitals throughout the UK. Previous reviews were published in 1995 and 2000 and the latest report looks at data collected between January 2001 and February 2006. About 288,000 dose measurements have been analyzed for medical x-ray examinations and therapeutic procedures, such as insertion of a pacemaker, in which x-rays are used. The information in the latest review has been contributed by radiology departments in 316 hospitals across the UK.

      The review provides national reference doses for 38 different x-ray procedures carried out on adults and four types of x-ray examinations on children. The aim is to enable hospitals to check where their x-ray dose levels sit on the national scale. The reference doses presented in the latest review are on average about 16% lower than those in the 2000 review, and have more than halved over the last 20 years.

      For the first time the review includes analysis of doses from dental x-ray examinations. These were gathered from more than 3000 dental practices throughout the UK. National reference doses are presented in this review for x-ray examinations of the full set of teeth and for x-rays of single teeth.

      In producing this review, the Agency has worked closely with hospital physicists and radiology department staff who supplied patient dose data, and with the dental X-ray Protection Service who supplied dental dose data.