The National Radiological Protection Board hopes that the radiation doses received by patients from medical diagnostic X-rays will fall by half over the next few years, as a result of stricter procedures which it proposed yesterday.
Medical X-rays form 90 per cent of the dose which most people receive from 'artificial' sources of radiation, according to the board's secretary, Geoffrey Webb. A modest reduction in the doses from diagnostic X-rays could make a major difference to the public's radiation exposure.
He added: 'If the average dose in a department is high, there's probably something wrong with the department's procedures as a whole. They may be using older equipment or procedures, but something is causing them to use higher doses to get the same diagnostic information as the best hospitals.'
The new rules are part of sweeping recommendations on reducing radiation exposure which the board is putting forward following an international review, in 1990, which determined that radiation was about three times more hazardous than had been thought. But Britain will be introducing restrictions on the nuclear industry and on other users of radiation - such as industrial radiographers - that are tighter than the international norm if the Government follows the board's advice, as it is expected to do.
In addition, by making its position public now, Britain may be able to influence a European Community directive on radiation safety standards due in 1995.
The board is recommending that the legal dose limit for registered radiation workers should be reduced to 20 mSv a year from the existing 50 mSv a year. Doses to the public should come down from 5 mSv to 1 mSv, it says. The international recommendation is laxer: a worker could be exposed up to 50 mSv in any one year, provided the average over five years did not exceed 100 mSv (ie an average of 20 mSv a year over five years).