FEASIBILITY STUDY OF X-RAY-DIFFRACTION COMPUTED-TOMOGRAPHY FOR MEDICAL IMAGING

A feasibility study of soft-tissue imaging based on x-ray wide-angle d iffraction contrast has been performed at the medical beamline of the European Synchrotron Radiation Facility (ESRF). The technique employs computed-tomography algorithms to reconstruct from one data set the sp atial distribution of several tissues differentiated by their diffract ion properties. Radial diffraction profiles are measured in parallel p rojections from the sample and decomposed into material-selective weig hting factors, which form the sinograms for the reconstructions. Atten uation effects-inherent in imaging techniques using scattered radiatio n-are efficiently corrected for by a ray-tracing method applied to the corresponding absorption image. Images of 7 cm diameter samples compo sed of fat, bone and muscle were generated at 60 and 80 keV x-ray ener gy. The highest surface-absorbed dose was 24 mGy, but substantial cont rast could still be obtained at 7 mGy, indicating potential applicabil ity in medical imaging. The dominant noise contribution in the images stems from the detection system, pointing to a possible decrease in th e surface-absorbed dose for an optimized system of more than a factor of 2.