The X-ray technique is a non-destructive method of detecting surface and subsurface defects in a part or assembly. X-rays are produced when electrons traveling at a high speed in a vacuum are stopped by matter. Some of the radiation will be absorbed and scattered as it passes through the part. When the beam of penetrating radiation is directed through the part then the amount of radiation passing through the part is observed or recorded on a photographic type film called X-ray film. After the film is processed, a shadow picture of the internal structure of the part is obtained. This technique is used to inspect castings, welds, wrought structures, adhesive bonds composites, aircraft structure and instruments.