Radiography is the use of ionizing radiations to view objects in a way that can't be seen otherwise. It is not to be confused with the use of ionizing radiation to change or modify objects; radiography's purpose is strictly for viewing. Industrial radiography has grown out of engineering, and is a major element of nondestructive testing (NDT). It is a method of inspecting materials for hidden flaws by using the ability of short X-rays and Gamma rays to penetrate various materials. In simple terms, a radiograph is a photographic record produced by the passage of X-rays or gamma rays through an object onto a film or other recording medium (see Figure 1). The developing, fixing and washing of the film after exposure can be performed manually or by automated processing equipment. The development process begins after the film is exposed to the radiation and an invisible change called a latent image develops on the film emulsion.

These exposed areas become dark when the film is placed in a developing solution. The degree of darkening that occurs during this process depends on the amount of exposure that occurred. The next step is to place the film into a special bath and rinse it to stop the development process. Lastly, the film is put into a fixing bath and then washed to remove the fixer solution. At this point the film is fully developed, the process is complete and the radiograph is ready to be handled and analyzed.As the digital world has evolved, a quicker and much more efficient alternative to the meticulous film development process has also emerged to benefit the radiography NDT community. Computed radiography, which is described in the related article entitled “Computed Radiography in the Pacific Northwest: Benefits, Drawbacks and Requirements”, makes use of an alternative image capturing media and development process.

»	Either an X-ray machine or a radioactive source (Ir-192, Co-60, or in rare cases Cs-137) can be used as a source.
»	Iridium-192 (symbol Ir192) is an isotope of iridium. Its half-life is 73.83 days. It decays by emitting beta particles and gamma radiation.
»	Iridium-192 is used as a gamma ray source in industrial radiography to locate flaws in metal components. It is also used in radiotherapy as a radiation source.
»	Cobalt-60 (60Co) is a radioactive isotope of cobalt. Due to its short half life of 5.27 years 60Co is not found in nature. It is produced artificially.

An X-ray generator is a device used to generate X-rays. These devices are commonly used by radiographers to acquire an x-ray image of the inside of an object. A homogeneous beam of X-rays is produced by an X-ray generator and is sent to an object. According to the density and composition of the different areas of the objects, X-rays are more or less absorbed. They are then captured behind the object by a detector (film sensitive to X-ray, digital detector) which give a 2D image of this as if it was transparent.