CHAPEL HILL - Studies of a new X-ray imaging method show the technique produces significantly better pictures of breast tissue than conventional X-rays and could make mammography more effective in revealing tumors, University of North Carolina at Chapel Hill scientists say.
If further work on it succeeds, the technology could be used widely, the researchers say.
A team led by Drs. Etta Pisano, professor of radiology at the UNC-CH School of Medicine, and Dale Sayers, professor of physics at N.C. State University, is developing what it calls Diffraction Enhanced Imaging, or DEI. Other institutions involved include Brookhaven National Laboratory's National Synchrotron Light Source, the Illinois Institute of Technology and the European Synchrotron Radiation Facility in Grenoble, France.
"The images we have, which are the first to be published using this new DEI technology, are just spectacular," said Pisano, also chief of breast imaging and a member of the UNC Lineberger Comprehensive Cancer Center. "Once we've overcome some technical challenges and adapted it for clinical use, DEI conceivably could be used not only in breast imaging, but in any medical and non-medical application involving X-rays. The sky's really the limit."
A report on the latest research appears in the March issue of Radiology, a top medical journal. Besides Pisano and Sayers, authors are Drs. R. Eugene Johnston, David B. Washburn, Mary V. Iacocca and Chad Livasy of radiology and pathology at UNC-CH, as well as graduate student Miklas Z. Kiss of N.C. State. Others are Drs. Dean Chapman of IIT, Joseph Geradts, formerly of UNC-CH but now at Oxford University in England, Zhong Zhong of Brookhaven and William Tomlinson of the European Synchrotron Radiation Facility.
The new research involved creating images of seven breast cancer tissue specimens at Brookhaven using the DEI technique and conventional digital X-ray images at UNC-CH. Researchers then carefully compared the images and found tumor visibility was superior with DEI in six of the seven specimens. Pathologic studies, showing that the increased detail reflected real structural information about tumors and was not manufactured by the technique itself, confirmed the results.
DEI differs from traditional X-ray radiography in that an "analyzing" crystal is placed in the X-ray beam between the object being studied and an image-creating medium such as film, X-ray plate or digital detector, Sayers said. The silicon crystal diffracts a particular wavelength of X-ray through a physics principle known as Bragg's law.
When the crystal is adjusted and two images taken and processed, the result is one image based on X-ray absorption that is similar to a standard X-ray and a new image based on refraction, he said. Refraction is a process where light, including X-rays, deviates in angle slightly -- something like a ricochet -- because of differences in the atomic density of the materials it passes through.
"In a tissue sample, if a tumor is embedded in normal tissue there's usually a density difference that results in the defraction, which is detected and imaged and has now been shown to be more sensitive in some cases for features diagnostic of cancer, " Sayers said.
Pisano said the team still has a long way to go before they have a practical machine that can be used clinically but the researchers believe they are closing in on a big advance in medicine.
"Obviously we can't bring everybody to the world's few synchrotrons for routine mammography, and so we have to make this technology clinically portable," she said. "Right now we think that's doable."
Synchrotrons, like the one at Brookhaven, are large accelerator machines that speed up atomic particles such as electrons and positrons to create electromagnetic radiation useful in various ways.
"From a personal perspective, I've been excited by the potential for DEI to revolutionize X-ray imaging," Sayers said. "If the next phases of our work are successful, then in 10 to 20 years, it is possible that almost every X-ray imaging apparatus in the world would be replaced by a DEI apparatus. This feeling of excitement is magnified by the fact that we have such an outstanding team, not only in scientific ability but also as colleagues and friends."
The U.S. Army, the U.S. Department of Energy and the State of Illinois Higher Education Cooperation Agreement have supported the research, which began more than seven years ago.
Note: Pisano can best be reached at etpisano@med.unc.edu . Her number is (919) 966-6957.
Contact: David Williamson, (919) 962-8596.
Journal
Radiology