BASIC FUNDAMENTALS OF RADIOGRAPHIC INSPECTION.
This chapter will provide guidance for radiographic inspection. Additional helpful material is cited in the form of
references, primarily books and standards. The references are listed at the end of this chapter.
Basics of Radiographic Inspection.
X and gamma radiographic inspection uses the penetrating abilities of electromagnetic radiation to examine the interior
of objects. Three prime factors determine the amount of information that radiography can provide about an object.
a. The composition of the object.
b. The product of the density and the thickness of the material making up the object.
c. The energy of the X or gamma rays incident upon the object.
Discontinuities within the object can cause localized changes in the first two characteristics above and thus, become
General Nature Of X and Gamma Radiation.
X-rays and gamma rays are forms of electromagnetic radiation, as are visible light, ultraviolet light, infrared radiation,
microwaves and radio waves. All together these types of radiation make up the electromagnetic spectrum. (Figure 6-1).
Electromagnetic radiation is dualistic; that is, it exhibits some characteristics of a wave and some characteristics of a
particle. In this case the particle is called a photon, which is a quantum of light. Depending upon the application, X-
rays may exhibit more wave-like behavior or more quantum-like behavior.
Figure 6-1. Electromagnetic Spectrum.