Section I. IONIZING AND NONIONIZING RADIATION
The earth is full of radiation, some natural and some man-made. Radiation is in
the air we breathe, the water we drink, and the ground we walk on. Man has added to
the natural radiation in the form of medical and dental x-rays, the mining of uranium,
and nuclear weapons and power plants. With the increasing use of radiation in all
phases of our lives--in peacetime and war--it is essential to understand the
fundamentals of radiation and to be prepared to treat the victims of the misuse of
radiation or radiation accident.
a. Radiation is the transmission of energy in the form of waves or particles. Two
forms of radiation which are not usually harmful to the body are visible light and sound
(nonionizing radiation). Ionizing radiation, radiation which has the ability to change
atoms in the body into their basic charged particles (ions), causes problems in the
molecules of various body tissues. Depending on the extent of exposure, a person may
die early or suffer complications such as leukemia.
b. Of the four basic types of nuclear particles, three are ionizing radiation: alpha
particles, beta particles, and gamma rays. A neutron, an uncharged atomic particle
found in the center of all atoms except hydrogen, is the fourth basic type of nuclear
(1) Alpha particles. These particles represent the nucleus of the atom and
are rather large, slow moving, positively charged particles. Alpha particles have a
minimal penetrating ability and a very short range. A sheet of paper or skin can stop
these particles. Unless they are inhaled or ingested, alpha particles probably will not
damage the human body.
(2) Beta particles. These particles have a negative charge and correspond
to the electron of an atom. Beta particles move a little faster than alpha particles and
can, therefore, penetrate a little more than alpha particles. Heavy clothing can stop
these particles. Beta particles would have to enter the body through the nose, mouth,
or an open wound to cause damage.
(3) Gamma rays. Gamma rays are waves of energy with a velocity of the
speed of light. They have high penetration power into the body and lead to gene
mutations in humans. Gamma rays can only be stopped by substances such as thick
concrete or lead shielding.