SUMMARY. Diffraction enhanced imaging (DEI) is a new x-ray radiographic imaging modality using synchrotron x-rays which produces images of thick absorbing objects that are almost completely free of scatter. They show dramatically improved contrast over standard imaging applied to the same phantoms. The contrast is based not only on attenuation but also the refraction and diffraction properties of the sample. The diffraction component and the apparent absorption component (absorption plus extinction contrast) can each be determined independently. This imaging method may improve the image quality for medical applications such as mammography.

Seven breast cancer specimens were examined with diffraction-enhanced imaging at 18 keV with a silicon crystal with use of the silicon 333 reflection in Bragg mode. Images were compared with digital radiographs of the specimen, and regions of increased detail were identified. Six of the seven cases (86%) showed enhanced visibility of surface spiculation that correlated with histopathologic information, including extension of tumor into surrounding tissue.

Synchrotron based mammography imaging experiments have been performed with monochromatic x-rays in which a laue crystal placed after the object being imaged has been used to split the beam transmitted through the object. The X27C R&D beamline at the National Synchrotron Light Source was used with the white beam monochromatized by a double crystal Si(1 11) monochromator tuned to 18keV. The imaging beam was a thin horizontal line approximately 0.5mm high by 100-wide. Images were acquired in line scan mode with the phantom and detector both scanned together. The detector for these experiments was an image plate. A thin Si(1 1 1) laue analyzer was used to diffi.act a portion of the beam transmitted through the phantom before the image plate detector. This "scatter fiee" diffracted beam was then recorded on the image plate during the phantom scan. Since the thin laue crystal also transmitted a hction of the incident beam, this beam was also simultaneously recorded on the image plate. The imaging results are interpreted in terms of an x-ray schliere or rehctive index inhomogeneities. The analyzer images taken at various points in the rocking curve will be presented.