Tomography x-ray detector

A small but very efficient X-ray detector operating in a current integrating mode for use in high speed tomography apparatus comprises a scintillator that is entirely coated with a highly reflective matte material except for a relatively small-area window. A PIN photodiode is juxtaposed with the scintillator opposite the window and the two are secured together at an optical interface comprising a transparent adherent material preferably having an index of refraction between the indices of the scintillator and the photo-diode. The ratio of the active surface area of the photo-diode to the area of the scintillator coated with reflective material is appreciably less than unity. 11 claims.