1. An apparatus for x-ray imaging of a subject, comprising: an x ray source emitting a spectrum of radiation of low energy component as well as high energy component to be attenuated by the subject; at least one CR plate adapted to absorb mainly said radiation of low energy component that was attenuated by the subject, wherein low energy x rays image can be attained on said at least one CR plate; a DR plate adapted to absorb said high energy component, wherein said DR plate is placed further to said CR plate relative to the subject, so as to attain image from higher energy x rays; and a processor adapted to process CR and DR images obtained in a single irradiation of the subject so as to obtain a third combined processed image.