Radiation image detector

Provided is a radiation image detector, including: a substrate; an optical image detector located on the substrate; and a radiation conversion layer located above the optical image detector to convert radiation into visible light. The optical image detector includes a photosensitive pixel array formed by a plurality of photosensitive pixels arranged periodically; each photosensitive pixel includes a photoelectric conversion layer which is capable of converting the visible light into electric charges. The photoelectric conversion layer includes an active region and an inactive region. The active region occupies less than 70% of the area of the photoelectric conversion layer. Each photosensitive pixel further includes a light-guide layer located between the radiation conversion layer and the photoelectric conversion layer and configured to guide the visible light to the active region.