A basic understanding of radiation biology is necessary for the dental x-ray
specialist. In the next few paragraphs, a review of some basic concepts will be
discussed along with diagrams representing atomic and molecular configurations. This
lesson discusses the interaction and factors influencing cells, tissue, and matter when
exposed to ionizing radiation.
TERMS RELATING TO RADIATION BIOLOGY
a. Ionization. The gain or loss of electrons from an electrically neutral atomic or
molecular configuration caused by radiation. There are other ways whereby electrons
may be gained or lost, but we are most concerned with changes brought about by
b. Element. A simple substance that cannot be broken down by chemical
means. An example of an element is oxygen.
c. Atom. The smallest unit of an element that still retains the properties of that
d. Compound. A complex substance formed by a chemical union of two or
more elements. An example of a compound is water (H2O).
e. Molecule. The smallest unit of a compound.
COMPONENTS OF THE ATOM
The atom is comprised of protons, neutrons, and electrons. The nucleus of an
atom contains protons, which have a positive charge. The nucleus also contains
neutrons, which are neutral. Electrons, which are negatively charged, revolve or orbit
about the nucleus. Generally, protons and electrons in an atom are equal in number.
Figure 2-1 represents an atom with one proton, one neutron, and one orbiting electron.
Figure 2-1. Components of the atom.