Ray inspection is one of the earlier application of material testing methods. 1896, that is, the German physicist R?ntgen (W.K.R?ntgen) discovered Χ-ray the second year, the British Hall-Edwards (Hall-EdWards) and Radcliffe (Radcliffe) X-rays used for medical diagnosis; soon after he will be used for the inspection of metal X-rays. Gamma ray inspection began in 1925, when Pilon (H. Pilon) and Laborde (M.A. Laborde) with radium on the steam engine ray inspection. 1948, due to the emergence of artificial radioisotopes, gamma ray inspection is becoming more widely used.
Ray inspection in industry has a very wide range of applications, it is used both for metal inspection, but also for non-metallic inspection. The defects that may arise within the metal, such as porosity, inclusions, loose, cracks, unwelded and unfused, etc., can be inspected with rays. The industries where it is applied are pressurized equipment, aerospace, ships, weaponry, hydraulic sets and bridge steel structures.