Energy subtraction method with filtered X-rays for the detection of contrast media

The energy subtraction method is employed for contrast media measurements focusing on tumors. An X-ray filter which had a K-edge a little higher than the one of the contrast media, was used to make X-ray spectra sensitive to the contrast media. For practical reasons, a CdZnTe detector was used for the photon detector. The thickness of the contrast media was estimated from the measured energy spectra of X-rays, even in the presence of Al, used to simulate bones.