Patent ID: 7780351
Filing Date: 2010-08-24
Classification: A61B

Abstract:
1. A method for acquiring and applying a calibration with a calibration body to determine gray-scale values for volume elements of a second body to be mapped using an x-ray image recording system, comprising: providing an x-ray image recording system comprising a C-arm including an x-ray source and an x-ray detector positionable about an arc so that the source can be sequentially positioned in multiple focal positions along the arc wherein each focal position corresponds to an origin of x-ray radiation; with a first focal position as a center of rotation for the source, positioning the source at multiple rotational positions to generate radiation along different paths to create a first series of different projection images, with each projection image in the first series based on generation of radiation from the same origin; with the source in the first focal position, recording in the first series of projection images at least two different projection images of the calibration body and a further projection image of the calibration body, each projection image corresponding to a different rotational orientation about the first position, wherein individual features of the calibration body are predetermined and known; determining a mapping rule for mapping the at least two different projection images onto the further projection image; applying the mapping rule to calculate a virtual projection image, portions of which cannot be shown by individual recordings in the first series; and applying the virtual projection image, on the basis of the mapping rule, to derive a mathematical rule for the back projection of the virtual projection image onto the volume elements of the calibration body based on the individual features mapped between the two different projection images and the further projection image to generate the virtual projection image; and applying the mapping rule and the mathematical rule to determine gray scale values for the volume elements of the second body in a back projection of a virtual image of the second body.