1. A method of x-ray imaging a patient's breast comprising: immobilizing the breast between a breast platform and a compression paddle, which in turn are between an x-ray source and a digital imaging receptor; imaging the immobilized breast with x-rays from the source that pass through the breast and impinge on the receptor, from a number of different positions of the source and receptor relative to the breast, to derive image data for the respective positions; said imaging comprising moving the receptor relative to the immobilized breast while remaining substantially parallel to the same plane and moving the source around the immobilized breast for imaging from each of said different positions; and using said image data to form images of the breast, wherein each of at least some of said images is formed from image data acquired for two or more of said different positions.