Connected with this physical half-life of the isotope is another kind
of half-life called the "biological half-life" which is the amount of time
it takes for one-half of the radioisotope to be removed from the body,
elimination of waste matter.
through
A furtner aspect of radiation that is of interest
in the present context is that charged particles lose energy along their path
to the mediums
they are nenetrating.
even produce radioactivity.
This energy may break up molecules or
For the energetic rarticles of interest here,
thousands of molecules may he affected along the track of the particle.
Because of the positive-negative electrical charges,
tear electrons from atoms they strike.
these particles can
It takes anywhere from ten to one
hundred electron volts of energy to tear an electron from an atom,
the radiation energy of particles is measured in the thousands
volts -- kev)
or millions
(million electron volts -- mev).
Usually
(kilo electron
Consequently,
particles in the kev or mev can disrupt or ionize thousands of other atoms
before their energy is used up and they stop.
Measurement
The amount of radiation may be measured in a number of different ways.
Of particular interest here are measures that indicate the interaction of
the radiation with various types of material.
The “Roentgen”
is a unit for exposure whicn indicates tne ability of the
X or gamma radiation to produce ionization in air.
The "Rad" is a unit of absorbed dose which indicates the amount of energy
absorbed in a material per unit mass of material.
The "Rem"
is the unit of dose equivalent.
The dose equivalent is for
for assessing the
radiation protection purposes and provides a common frame
body.
combined effects of different kinds of radiation on the human
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