An X-ray sensitive coating (22) for a flat panel direct conversion X-ray detector for medical or industrial imaging. A composite particle-in-binder (PIB) material (22) may contain X-ray photoconductive particles (23) such as PbO (lead monoxide) in a binder of polyimide (23). This PIB material may be prepared in precursor paste form, and applied as a coating (22) onto a thin film transistor array (26) having a storage capacitor (31) at each pixel (30). The coating (22) is cured, and an electrically conducting layer (34) is applied to the exposed surface of the coating (22), to provide a bias voltage. X-ray photons striking the photoconductive particles (23) cause localized electrical conduction proportional to the number of photons. This charges respective capacitors (31) that provide image data input to a computer.