Patent ID: 7920735

Claim:
A method for automatically differentiating at least one of bones and other calcium-containing materials and contrast agent in soft tissue of an object area, in which the method comprising: recording two computed tomography pictures of the object area at different spectral distribution of X-radiation, reconstructing from raw data of the two computed tomography pictures two image data records of the object area that include X-ray attenuation values of voxels of the object area at the respective spectral distribution of the X-radiation, each voxel including two X-ray attenuation values corresponding to the two image data records, calculating from the two image data records, for voxels of at least one slice of the object area, a ratio r, said ratio r resulting from at least one of the two X-ray attenuation values of the respective voxel and two averaged X-ray attenuation values obtained by averaging the X-ray attenuation values of voxels inside a volume around the respective voxel in the respective image data record, and X-ray attenuation values o1, o2 of soft tissue or blood at the respective spectral distribution of the X-radiation, using the following equation, r = x 1 - o 1 x 2 - o 2 x1, x2 being the X-ray attenuation values or averaged X-ray attenuation values at the respective spectral distribution of the X-radiation; and assigning to the respective voxel, upon overshooting of a threshold value for at least one of the ratio r and a value r′ derived therefrom, the contrast agent or calcium-containing material as a function of a magnitude of at least one of r and r′.