WASHINGTON -- The FDA has approved the first x-ray mammography device that provides 3-D images of the breast.

Approval of the Selenia Dimensions System was based on two studies asking radiologists to review 2-D and/or 3-D images from over 300 mammographies. Radiologists who viewed the 2-D and 3-D models were 7% more accurate in distinguishing cancerous and noncancerous cases than those who only used a 2-D image, an FDA statement said.

Combined use of the 2-D and 3-D imaging systems approximately doubles the radiation dose a patient receives, the statement said, but the combination increases cancer risk by less than 1.5% relative to natural cancer risk, and by less than 1% compared with the use of 2-D imaging alone.

The increase in accuracy of using both systems reduced the number of women recalled for a diagnostic workup, the statement added. In 10% of cases, patients who receive a 2-D scan require additional tests to work up abnormalities that are later determined to be noncancerous.

The device is an upgrade to the approved 2-D imaging system made by the company Hologic.

Healthcare professionals using the new system will require eight hours of training with the diagnostic tool before it can be used on patients as part of the Mammography Quality Standards Act. Facilities installing the machine also will be provided with a manual from the manufacturer that clearly lists required tests for initial and future quality control measures, the statement said.