A broad survey of direct and indirect modalities for x-ray detectors is provided. A review of the current state of research is critical to understanding worthwhile R and D efforts with the goal of pushing state of the art. The objective here is to survey relevant materials under investigation for both direct and indirect detectors for radiographic non destructive testing using x-rays. Ensuring that the warfighter has the best materials requires state of the art non-destructive testing equipment. Detectors play a crucial role in non-destructive testing and advances should be noted and pursued when applicable to radiographic inspection.