Which NDT method might employ X-rays or gamma rays?

Radiographic Testing employs X-rays or gamma rays to detect internal flaws within materials. This non-destructive testing method works by directing radiation towards a test specimen and capturing the resulting images on film or digital detectors. When the radiation passes through the material, any internal imperfections will absorb the radiation differently, producing varying densities on the film or image. This allows for the identification and characterization of flaws such as cracks, voids, or inclusions, providing a clear visualization of the internal structure.

In contrast, the other methods listed focus on different principles: Liquid Penetrant Testing involves applying a penetrating liquid to reveal surface defects, Magnetic Particle Testing uses magnetism to detect surface and near-surface flaws in ferromagnetic materials, and Visual Testing is based on the inspector's visual assessment of the surface for any obvious defects. These methods do not utilize radiation as a means of flaw detection, which is a critical distinguishing factor.