1. A method for producing an x-ray image, comprising the steps of: at respective time-separated times, generating a first x-ray image dataset containing image information of a body region of a subject and generating a second x-ray image dataset containing image information of substantially the same body region, at a same projection for each of said first and second x-ray image datasets; subtracting the image information in one of said first and second x-ray image datasets from the image information in the other of said first and second x-ray image datasets to produce a subtraction dataset containing image information; emphasizing the image information in said subtracted image dataset to obtain emphasized image information; and superimposing the emphasized image information of said subtraction image dataset on said image information of said second x-ray image dataset.