b. Photon Action Upon Living Cells.
(1) Living cells are composed of atoms and molecules. If the structure of
the atoms and molecules is changed, the cell may be adversely affected. When cells
are exposed to ionizing radiation, the structure of some of the atoms and molecules
within the cell are changed.
These are some of the effects that ionizing radiation has upon the cell.
(a) Cell death. The x-ray photon may strike a molecule in a sensitive
area of a living cell and cause cell death.
(b) Toxic substances. The body is composed of a high percentage of
water (H2O). The ionization (gain or loss of positive and/or negative charge) of atoms
and molecules results in the breaking of the hydrogen-oxygen bond. When this occurs,
there is a reforming of hydrogen and oxygen elements and hydrogen-oxygen
compounds. One compound resulting from this restructuring of the atoms and
molecules is hydrogen peroxide (H2O2). Hydrogen peroxide is highly toxic to cells. If
large amounts of toxic substances (hydrogen-oxygen compounds) are formed, cell
death will result.
(c) Mutated cell formation. The chromosomes, which are the blueprint
for the formation of new cells, are changed by excessive radiation exposure, resulting in
mutated cells. The new mutated cells do not function properly. When a cell is changed
in this manner, the life cycle or span of the cell is changed.
HARMFUL EFFECTS OF OVEREXPOSURE TO RADIATION
a. Somatic Effects.
(1) Erythema. This is the reddening of the skin, much like that of a sunburn;
however, radiation exposure affects deeper tissue.
(2) Radiodermatitis. This refers to dry, flaky skin that doesn't heal easily.
Ulcerations may become malignant. This may be seen when dentist or tech
consistently holds film in patients' mouths during exposure.
(3) Cataracts. An overexposure to the eye could result in cataracts (a
clouding of the lens or of its surrounding transparent membrane); however, this effect
will appear long after the original exposure.
(4) Cancer. The cause of most natural occurring cancers is unknown. With
increased exposure to radiation, there is an increase in the incidence of cancer.