Patent Number: 
Section: claims

1. A method of compensating for image faults in a digital x-ray image recorded by an x-ray system having a radiographic source, an anti-scatter grid and a digital x-ray detector, wherein the image faults result from de-centering, defocusing or defects in the anti-scatter grid or from the Heel effect, the image faults leading to an intensity reduction of primary radiation falling on the x-ray detector, the method comprising:determining a first intensity of the primary radiation before the primary radiation hits the anti-scatter grid;determining a second intensity of the primary radiation after the primary radiation has hit the anti-scatter grid;determining a reduction in intensity of the primary radiation caused by the anti-scatter grid based on the first and second intensities;determining a set of correcting parameters based on the determined reduction in intensity of the primary radiation; andcorrecting the x-ray image using the set of correcting parameters. 2. The method according to claim 1, wherein the digital x-ray detector is an image amplifier or a solid-state image detector. 3. The method in accordance with claim 1, wherein determining the first intensity of the primary radiation includes recording blank images with no object present in a radiation path between the radiographic source and the anti-scatter grid. 4. The method in accordance with claim 3, wherein a plurality of blank images corresponding to different distances between the radiographic source and the x-ray detector are recorded for determining a function related to intensity-reducing results caused by a de-centering of the anti-scatter grid depending on the different distances. 5. The method in accordance with claim 1, whereinthe x-ray image is recorded as a digital image matrix having a plurality of columns and rows, anddetermining the reduction in intensity of the primary radiation includes calculating a profile line representing the reduction in intensity reduction. 6. The method according to claim 5, wherein calculating the profile line includes summing up the columns. 7. The Method in accordance with claim 6, wherein the profile line is a one-dimensional vector having the summed columns as its vector elements. 8. The method in accordance with claim 5, wherein the profile line is smoothed by repeatedly applying a low-pass filter algorithm to the profile line. 9. The method in accordance with claim 5, wherein the profile line is a vector having vector elements scaled to values between 0 and 1. 10. The method in accordance with claim 5, wherein a center of the reduction in intensity is determined by locating a minimum of the profile line. 11. The method in accordance with claim 10, wherein a first and a second linear equation are determined, the first linear equation representing a left part of the profile line relative to the located minimum, and the second linear equation representing a right part of the profile line relative to the located minimum. 12. The method according to claim 11, wherein the first and second equations are determined using a linear regression algorithm. 13. The method in accordance with claim 12, wherein the set of correcting parameters includes the minimum of the profile line and a gradient of the first and second equations. 14. The method in accordance with claim 13, wherein an image brightness of the x-ray image is corrected using the minimum of the profile line and the gradient of the first and second equations. 15. An x-ray system for recording an x-ray image, comprising:a radiographic source;an anti-scatter grid;an x-ray detector; anda processing device for compensating for image faults resulting from de-centering, defocusing or defects in the anti-scatter grid or from the Heel effect, the image faults leading to an intensity reduction of primary radiation falling on the x-ray detector, wherein the processing device is configured to:determine a first intensity of the primary radiation before the primary radiation hits the anti-scatter grid;determine a second intensity of the primary radiation after the primary radiation has hit the anti-scatter grid;determine a reduction in intensity of the primary radiation caused by the anti-scatter grid based on the first and second intensities;determine a set of correcting parameters based on the determined reduction in intensity of the primary radiation; andcorrect the x-ray image using the set of correcting parameters.