Patent ID: 7583784

Claim:
A method for reconstructing computed tomography pictures from detector data of a CT that includes at least two radiation sources to generate conical beams, comprising: scanning an object, using at least two conical beams with fan angles of different sizes and measuring fields of different sizes, in at least one of a circular and spiral fashion, a first conical beam is larger than a second conical beam; measuring integral attenuation values of the first conical beam; reconstructing spatial attenuation values of the object by convolution and back projection using the measured integral attenuation values of at least the first conical beam that completely surrounds the object; scanning the object with the second conical beam, a measuring field of the second conical beam not completely surrounding the object; measuring integral attenuation values of the second conical beam; calculating an integral attenuation of virtual rays at least in an area outside of the measuring field of the second conical beam from the reconstructed spatial attenuation values of the area reconstructed using the measured integral attenuation values of the first conical beam; supplementing the measured integral attenuation values of the second conical beam with the calculated integral attenuation of the virtual rays at an edge of the second conical beam to provide a supplemented data set; reconstructing the spatial attenuation values of the object, at least in the measuring field of the second conical beam, based on the supplemented data set, to reconstruct the computed tomography pictures, wherein the at least two conical beams used, include different energy spectra, and the difference is considered when calculating the integral attenuation values of the virtual rays.