1. An apparatus for improved angiographic X ray imaging of a subject's body infused with contrast agent, said apparatus comprising: an x ray source adapted to emit X rays directed to pass through the subject's body wherein said X ray beam is polychromatic; a sensor system adapted to receive attenuated X rays that passed through the subject's body, wherein said sensor comprises detection means divided into a plurality of detector elements, wherein each one of said plurality of detection elements is adapted to convert photon energy of a portion of said attenuated X rays into electric charges; at least one readout chip divided into a plurality of channels wherein each one of said plurality of channels is electronically connected to one of said plurality of detection elements and wherein each one of said plurality of channels is adapted to convert said electric charges into digital data; acquisition system adapted to receive said digital data from said sensor and generate at least two electronic representations wherein one of said at least two electronic representations is attained from low energy photons and another one of said at least two electronic representations is attained from high energy photons wherein said at least two electronic representations are measured simultaneously at the subject and at a certain position of said X ray source; processing means adapted to manipulate said at least two electronic representations into at least one image; displaying means adapted to display said at least one image; whereby said at least one image attained from at least two energy bins amplify the appearance of the contrast agent in the blood vessels in respect with the surrounding tissues of the subject's body.