While the quality of mammogram testing is being debated in the UK, the US has taken the next step by having all mammography clinics accredited.

Women's groups were concerned about standards at the 30 per cent of clinics not already accredited in the US. Some clinics were giving inaccurate results and women were receiving too high doses of radiation.

Clinics have until next October to reach the standards necessary for accreditation, states the US Food and Drug Administration (FDA), and then will be inspected annually.

In addition, doctors employed to interpret mammograms will also have to be certified by an approved professional body and have continuing education in reading mammograms.

The x-ray equipment will have to be specially designed for mammography and the average dose delivered during a single view must not exceed 3.0mGy for film screen mammography.

The US National Cancer Institute is no longer recommending routine mammography for women under 50.

This new recommendation is at odds with the American Cancer Society and the American College of Radiology, which maintain that women aged over 40 should be regularly screened.