Figure 2-24. Laser beam strength.
Laser radiation should not be confused with ionizing radiation (radiation such as
X-rays and gamma rays produce a change in neutral atoms or molecules). The biologic
effects of laser radiation are essentially those of visible, ultraviolet, or infrared radiation
upon tissues. Radiant intensities typically produced by lasers are as strong as the
radiation previously only produced by the sun, nuclear weapons, burning magnesium, or
arc lights. This is one of the important properties that make lasers potentially
hazardous. Laser radiation which hits biologic tissue will be reflected, transmitted,
and/or absorbed. The degree to which each of these effects takes place depends on
the various properties of the tissue involved. For example, laser radiation is more
readily absorbed by darker pigmented tissue and the dark brown or black pigment found
in the skin, hair, and retina.
a. Skin Effects. Adverse effects from laser radiation vary depending on the
exposure dose rate (amount of energy) transferred, and the conduction of heat away
from the absorption site. Overradiation from lasers can have these ill effects on the
(1) Erythema. Erythema of the skin is an abnormal redness caused from
damaged or killed cells. This coloration may be temporary or last for years.
Surface charring. The surface of the skin looks as though it has been
Deep tissue damage. The body cells for several layers have been