The production of radiographs using an isotope as a source of radiation.
Radioactive isotopes have largely replaced radium and X-ray machines for inspecting welds, castings, and finished products for voids and cavities. Isotopes such as cobalt-60, cesium- 137, and iridium- 192 are used in radiographic testing of lead, steel, and iron castings.
Procedures using isotopes are similar to the techniques used with X-ray machines. A radiation source is placed on one side of the material to be tested, and photographic film on the other. After exposure, the film is developed and interpreted.
Isotope radiography has proven safe, reliable, and versatile. Inspection of complicated machinery can be made without dismantling. Radiation sources can be of any desired shape or size, and they offer high radioactivity at relatively low cost.