Researchers have built a prototype CT scanner for breast imaging that takes 300 sectional X-ray images through the breast. These are assembled into a single, three-dimensional composite picture that provides a clearer view through all tissues of the breast than is possible with conventional mammography, which takes two X-ray images from two vantage points.

"It's the difference between taking a picture of a crowd from across the street, versus circling the crowd and shooting hundreds of separate photos along the way, each photo only two or three people deep," said John Boone, Ph.D., professor of radiology and biomedical engineering at the University of California, Davis. "Your chances of finding a particular person in the crowd are going to be a lot better with more photos."

With CT, it may be possible to detect tumours about 5 millimeters across, about the size of a garden pea and less than half of the diameter of malignancies that generally show up in standard mammograms, said Boone, who presented preliminary results.

"The earlier and smaller a cancer is when it is detected, the less the chance that it has spread to the lymph nodes, lungs or bones, and the greater the chance for a permanent cure and for breast preservation," said Lydia Howell, professor of pathology at UC Davis and a volunteer in early testing of the CT scanner.

Boone and his colleagues revisited the issue and discovered that earlier estimates of radiation exposure assumed the breast and entire chest would be subjected to X rays from standard CT machines. When Boone recalculated the exposure rates based on imaging the breasts alone, the radiation dosage was no more than that of a standard mammogram.

"Don't put off getting mammograms, because it will take some time to develop this newer technology," said Karen Lindfors, a UC Davis radiologist and collaborator with Boone in developing the scanner.; Source: Whitaker Foundation