Scientists have developed a three-dimensional (3D) breast radiography that uses a radiation dose much lower than the 2D radiography currently used in clinics. The new method produces 3D diagnostic computed tomography (CT) images with a spatial resolution that is two or three times higher than present hospital scanners, but has a radiation dose that is 25x lower.
This breakthrough can potentially overcome the main obstacle that limits conventional CT imaging of breast, which is the high radiosensitivity of the breast glandular tissue. The current breast cancer screening method is typically dual-view digital mammography, which only provides two images of breast tissue. Therefore, 10% to 20% of breast tumors are not detectable on mammograms, and mammograms can sometimes appear abnormal, even when no breast cancers are actually present. The technique of CT, which uses x-rays for precise 3D visualization of body organs, cannot be routinely used in breast cancer diagnosis. The breast is radiosensitive and so the risk of long-term effects from CT is considered too high.
Considering these limitations, the scientists combined high-energy x-rays, phase contrast imaging, and the sophisticated mathematical algorithm of equally sloped tomography (EST). Because tissues are more transparent to high-energy x-rays, fewer doses are deposited, with a 6x reduction in radiation dose. Also, phase contrast imaging uses much fewer x-rays to obtain the same image contrast. Finally, EST needs 4x less radiation to obtain the same image quality.
Five independent radiologists did a blind evaluation of the images and ranked them as having the highest sharpness, contrast, and overall image quality compared to 3D images of breast tissue created by other standard methods.
“This new technique can open up the doors to the clinical use of computed tomography in the breast diagnosis, which would be a powerful tool to fight even better and earlier against breast cancer,” says Prof. Maximilian Reiser, director of the Radiology Department of the Ludwig Maximilians University in Munich, which provided the medical expertise for this research.
This new technology is still in the research phase, and it will not be available to patients for some time. Before it can be implemented in clinics, it needs an x-ray source small enough to become commonly used for breast cancer screening.
“Many research groups are actively working to develop this device and once this hurdle is cleared, the new x-ray technique is poised to make a big impact on society,” concludes co-author Emmanuel Brun, PhD, of the European Radiation Synchrotron Facility.
The results of this method were published in Proceedings of the National Academy of Sciences (PNAS) (2012; doi:10.1073/pnas.1204460109).