WASHINGTON -- The Food and Drug Administration said Friday it has approved the first mammography device that generates 3-D images of the breast, potentially helping doctors spot more cancerous tumors.

The Selenia Dimensions System from Hologic Inc. offers both 2-D and 3-D X-ray images, providing additional viewpoints of the breast.

The FDA says the new system doubles the radiation exposure for patients, but also increases the accuracy of diagnosis. As a result, fewer women are expected to undergo additional scans.

"Physicians can now access this unique and innovative 3-D technology that could significantly enhance diagnosis and treatment approaches," said Jeffrey Shuren, director of the FDA's device division, in a statement.

The FDA approved the device based on two studies in which X-ray specialists demonstrated a 7 percent improvement in spotting cancerous tumors when viewing images from Hologic's device, compared with traditional 2-D images. Such images can cause visibility problems due to overlapping skin, which can hide tumors or create the appearance of tumors where there are none.

Approximately one in eight women will be diagnosed with breast cancer in her lifetime, according to the National Cancer Institute. The institute recommends women ages 40 and older have a mammogram every one to two years.

The Selenia device is already approved in Europe, Latin America and Asia.