Patent ID: 7778383

Claim:
A method for measuring dual-energy X-ray attenuation data of an object under examination by means of a computed tomography system, the tomography system comprising a rotatable holder being rotatable around a rotation axis, an X-ray source comprising a first X-ray focus point and a second X-ray focus point, the X-ray source being mounted at the rotatable holder, and an X-ray detection device comprising a plurality of detector elements, the detector elements being divided into a first group of first detector elements and a second group of second detector elements, wherein the first and the second detector elements exhibit different spectral sensitivities, and the X-ray detection device being mounted at the rotatable holder opposite to the X-ray source with respect to the rotation axis, the method comprising the steps of: adjusting the X-ray source such that it emits X-rays originating from the first X-ray focus point, acquiring first X-ray attenuation data separately with the first detector elements and with the second detector elements, moving the X-ray focus from the first X-ray focus point to the second X-ray focus point, and acquiring second X-ray attenuation data separately with the first detector elements and with the second detector elements, wherein the two X-ray focus points are spatially separated from each other such that a first beam path originating from the first X-ray focus point penetrates a certain voxel within the object and impinges on a first detector element and a second beam path originating from the second X-ray focus point penetrates the same voxel and impinges on a second detector element, and wherein the X-ray focus is moved in a discrete manner from the first X-ray focus point to the second X-ray focus point.