An imaging system is provided for various non-invasive medical and non-medical imaging. The imaging system includes a tunable X-ray source for emitting X-rays having a substantially monoenergetic spectrum and an energy discriminating detector for generating a detector output signal in response to the X-rays incident on the energy discriminating detector. The imaging system also includes a system controller comprising an X-ray controller for operating the tunable X-ray source and data acquisition circuitry for acquiring the detector output signal from the energy discriminating detector.