Scientists at the University of North Carolina – Chapel Hill (UNC-CH) are attempting to develop new technology to enhance the way images of the breast are acquired. The technology is called diffraction enhanced imaging (DEI) and currently involves using synchrotron radiation. A synchrotron is a particle accelerator and works by moving electrons in a circle to get them to emit electromagnetic waves (x-rays). The scientists say the DEI technology has the potential to produce significantly clearer images of the breast, greatly improving the way in which women are screened for breast cancer .
“It's extremely exciting,” said Etta Pisano, MD, Chief of Breast Imaging at UNC-CH. “If we solve this puzzle, we've basically developed a new way to use x-rays.” With conventional mammography, x-ray beams are absorbed by breast tissue. The more tissue present, the more x-ray radiation that is absorbed. A lump or abnormality in the breast is thicker and more dense than the surrounding tissue and will absorb more radiation. These abnormalities will show up as white regions on a mammogram film, and it is at these spots that radiologists will concentrate to determine whether the abnormalities are suspicious.
Though the radiation emitted during a conventional mammogram is minimal and not harmful, the scientists at UNC-CH are developing technology that involves absorbing a much lower amount of x-ray radiation than is absorbed by a normal mammogram. With the DEI technology, almost all of the x-ray radiation will go through the breast. Since the scientists are studying at what points the x-ray beams bend instead of which areas absorb the most radiation, most of the beam can travel through the patient, without being absorbed. All radiation passes through and out of the breast.
When capturing an image of the breast with DEI technology, a silicon crystal the size of a small mirror is placed directly in the path of the x-ray beams between the breast and the mammogram plate holding the film cassette. As the x-ray beams pass through the breast tissue, they bend as they encounter different tissue characteristics. When the x-ray beams exit the breast tissue back through the silicon crystal and onto the film, the spots where the beams were bent are recorded.
Since a mammogram with DEI technology involves absorbing less x-ray radiation, the scientists found that they could increase the radiation dosage to obtain clearer images of the breast without putting the patient at risk of radiation damage. A clearer image of the breast makes it easier to detect cancer.
Though the new technique is promising, the DEI technology is still in developmental stages and the necessary equipment not yet clinically available. In fact, the scientists conducted a substantial portion of their research at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France and other locations. There are only approximately 40 synchrotrons in the world; nearly 25% of those are located in the U.S. The scientists have been experimenting with the technology using breast tissue samples that have already been removed from mastectomy patients. When they need larger samples, the scientists use breast tissue from deceased patients in the morgue.
Two major obstacles for the scientists will be:
- proving that the DEI technology will be effective on full-size, live breasts
- determining whether breast compression is necessary
- and moving the technology from the synchrotron so that it is available in devices that can be placed in clinics.
With conventional mammography, the breast is compressed (flattened) to help spread out the tissue and make abnormalities easier to see. Preliminary tests have shown that compression may not be necessary with DEI technology, but extensive studies are still needed before the scientists can definitively say that x-ray images of the breast can be captured without breast compression.
Eugene Johnston, a physicist at UNC-CH, is excited about the possibilities of the DEI technology but is careful not to become overly optimistic. The project has the potential to be very exciting or fall apart, said Johnston in an interview published in the Raleigh, North Carolina News & Observer.
According to Dr. Pisano, the DEI technology could be used in any medical and nonmedical applications involving x-rays, once the researchers overcome technology difficulties and adapt DEI for use in clinical trials .
- The April 17, 2000 News & Observer report by
Carlene Hempel, “Bright Idea: Scientist Seek a Better Look at
Cancer,” is available at
http://search.nando.net/plweb-cgi/fastweb?getdoc+nao_public_archive
+nao_00+16617+0++%28diffraction%20x-rays%29%3AText- To learn more about mammography, please visit http://www.imaginis.com/breasthealth/mammography.asp
