A “shadow picture” or image produced by passing radiation, such as X-rays, gamma rays, or high-energy neutrons, through an object and recording the variations in the intensity of the emerging radiation on a sensitized film or screen.
A radiograph shows the gross structure of a metal or weld, such as the presence of blowholes, slag, high- or low-density inclusions, porous spots, cracks, or other defects or abnormalities which could not otherwise be found except by cutting through the material.