A rise in the number of X-rays is fuelling an increase in the amount of radiation people are exposed to each year, experts say.
There has been a 140 per cent rise in the use of computerised tomography (CT) scans over the past decade, the Health Protection Agency (HPA) said yesterday.
This has pushed up the annual radiation dose to each member of the public in the UK from all X-rays from 0.33 millisieverts (mSv) in 1997 to 0.4mSv.
However, this level is still within safe limits and is lower than in comparable countries, the HPA said.
CT scans involve taking an X-ray and using a computer to create detailed images of the inside of the body.
They can be used to diagnose or monitor a range of health problems, including bone disease and cancer.
CT scans make up about 68 per cent of the radiation dose to the public from all X-rays.
Some 1.4 million CT scans were carried out in 1997, jumping to 3.4 million in 2008, and around 20,000 of these were carried out on people with no symptoms who had opted for a private scan.
HPA experts believe about 46 million medical and dental X-ray examinations were carried out across the UK in 2008, a 10 per cent rise since 1997.
Some 67 per cent of these were performed in NHS hospitals and the rest in dental surgeries. The NHS Breast Screening Programme accounted for 2.03 million X-rays in 2008, up 45 per cent on 1997.
Medical X-rays make up about 15 per cent of the total amount of radiation people are exposed to. Other sources include radon from the ground.
The average radiation dose from all sources of ionising radiation remains about 2.7mSv per person per year.