Abstract: The x-ray imaging system comprises an x-ray source for producing an x-ray beam and an x-ray detector. The x-ray detector comprises a solid state integrated circuit having a silicon substrate. The detector is constructed as a PiN diode with the voltage bias direction parallel to the direction of incident radiation. A tissue sample, such as a breast, is positioned between the x-ray source and x-ray detector. The x-ray detector directly receives the x-ray photons transmitted through the tissue and produces electrical signals. The detector signals are processed to provide a digital image of the tissue sample.