Imaging characterization of an experimental apparatus for dual energy angiography

An angiographic practice an iodate contrast medium is injected in patient vessels with catheters. The absorption of X-rays rises immediately above the Iodine K-edge energy (33.17 keV), permitting to distinguish human soft tissues characterized by similar absorption's coefficients. Conventional image subtraction technique uses two images, acquired before and after the injection of the contrast medium, respectively. The vessels' morphology results from the difference of images so obtained. A different approach is presented: two quasimonochromatic peaks, having mean energies lower and higher than the Iodine K-edge, are produced with a pyrolytic graphite crystal monochromator and split in two thin parallel beams, respectively. These two beams impinge on phantoms simulating patient vessels and are detected with solid-state array detectors. The image results as the difference between the intensities of the two beams emerging from patient tissues and Iodine. In this work, we show results and first image of a phantom, characterized by calibrated vessels inside, obtained with an experimental apparatus to perform a double energy scanning in a 120 mm /spl times/ 120 mm field of view.