1. A breast x-ray imaging method comprising: concurrently x-ray imaging a first pattern of markers on or in a breast compression paddle and a patient's breast immobilized between the paddle and an x-ray imaging receptor to thereby form a composite x-ray image in which both markers of the first pattern of markers and the breast are imaged, wherein an x-ray image of at least a part of the first pattern of markers is superimposed on an image of the breast in said composite x-ray image and some of the markers are above a noise level of their spatial environment; computer-processing the composite x-ray image by (a) searching for image signals that are below a noise level of their spatial environment to thereby find locations in the composite x-ray image of markers of said first pattern of markers, and (b) removing contributions to the composite image of image markers at locations found in said searching but leaving, at said found locations, contributions of the breast that had been present at the found locations before said removing of marker contributions; computer-processing information related to found locations of markers to derive geometric information regarding markers of the first pattern of markers imaged in said composite x-ray image; computer-processing the geometric information to derive thickness information related to a thickness of the immobilized breast; and using the thickness information for at least one of assessment of the imaged breast and further x-ray imaging of the breast.