First results with a novel X-ray source for dual energy angiography

In angiographic practice an iodate contrast medium is injected in patient vessels with a catheter. The iodine is used because its linear absorption coefficient shows a K-edge at 33.169 keV. In digital subtraction angiography (DSA), some images are acquired before and during the injection of the contrast medium. The vessels´ morphology is obtained by subtracting the live images from the first (mask) image. A new approach is presented where two quasimonochromatic beams, having mean energies lower and higher than the iodine K-edge, are produced simultaneously-starting from an X-ray tube-by means of a pyrolytic graphite crystal monochromator. These two thin parallel beams impinge on the phantom simulating patient vessels and are detected with solid-state array detectors. The image results as the difference between the remaining intensities of the two beams. Performance-in terms of spatial resolution, contrast and reduction of iodine concentration in an invasive perfusion medium-are presented and compared with the full spectra subtraction method in use.