American Physical Society,
Austin, Texas, March, 2003

Better breast cancer screens?
3D X-ray mammograms could reduce false positives.
11 March 2003

ED GERSTNER

Breast cancer is highly treatable if detected early.
© SPL

A new three-dimensional breast imaging technique could increase the detection of early-stage cancers and reduce the number of unnecessary biopsies.

Called full-field digital mammography tomosynthesis, the technique is the first to use X-rays to produce 3-D breast scans, Jeffrey Eberhard of GE Global Research told last week's American Physical Society meeting in Austin, Texas.

Conventional mammography projects X-rays through the breast onto a sheet of photographic film or detector screen. Tumours, being more dense than most healthy tissues, show up as a shadow on the exposed film or screen.

This detects only 65-70% of breast cancers - small tumours can be obscured by other breast structures. Moreover, only 10-20% of women who have a biopsy turn out to have cancer, as overlapping images of healthy bits of tissue can sometimes look like a possible tumour.

Instead of keeping the X-ray source stationary, Eberhard's team scans the breast in an arc and collects a sequence of 10 to 20 images in a digital detector. They then use a computer to turn these images into a series of 2-D cross-sections. In this way they build up a much sharper and more detailed picture of the breast tissue.

Several 3-D imaging techniques are currently being developed - including ultrasound and magnetic resonance imaging. But X-rays could prove cheaper, faster and give better resolution.

"Even relatively small clinics have standard X-ray mammography equipment", says Eberhard. Tweaking it for 3D, he suggests, "would enable them to move into 3-D without the big investment of magnetic resonance imaging".

Preliminary clinical studies involving 200 patients at Massachusetts General Hospital look promising, Eberhard told the meeting: "People are pretty excited about this technology."

Each year in the United States alone, 44 million women are screened for breast cancer and 46,000 women die of the disease. In contrast to many other cancers, breast cancer is highly treatable if detected early.

Mammography tomosynthesis is also being looked into for lung-cancer screening, as it uses a 25% lower X-ray dose than conventional computer tomography scanning.

Ed Gerstner is the editor of the Nature Publishing Group's Physics Portal and Materials Portal.


© Nature News Service / Macmillan Magazines Ltd 2003