The invention relates to an X-ray detector with an array of pixels (10) that are composed of a scintillation layer (11), a coupling layer (12), and a sensitive layer (13). The coupling layer (12) comprises light guiding units (17) and shielding units (16), wherein the shielding units (16) are disposed above electronic processing circuits (15a, 15b) that are susceptible to disturbances by X-radiation. In an alternative embodiment, the coupling layer comprises a material like lead-glass that is transparent for light and absorbing for X-radiation. Preferably a wavelength-shifting material incorporated into the coupling layer (12) shifts the wavelength (.lamda..sub.1) of the photons generated in the scintillation layer (11) to values (.lamda..sub.2) at which the sensitive layer (13) has a higher sensitivity.