In general, RT is method of inspecting materials for hidden flaws by
using the ability of short wavelength electromagnetic radiation
(high energy photons) to penetrate various materials. The intensity
of the radiation that penetrates and passes through the material is
either captured by a radiation sensitive film (Film Radiography) or
by a planer array of radiation sensitive sensors (Real-time
Radiography). Film radiography is the oldest approach, yet it is still
the most widely used in NDT.