GE LOGIQ 500 Advanced Reference Manual page 188

Bioeffects
Mechanical Bioeffect
6–4
In a similar manner, the interaction of ultrasound energy with
tissue can produce a number of non-thermal or mechanical
effects. The most significant is cavitation which results from the
action of the oscillating ultrasound pressure on tiny gas bubbles
within the tissues. Cavitation has caused mechanical damage
on a cellular level such as microscopic tears and hemorrhage in
laboratory tests with small animals. The major contributing
factors can again be categorized as either tissue characteristics
or control parameters:
S
The physical characteristics of tissue such as the presence
and size of microscopic gas bubbles and the sensitivity of
the tissue to the effects of cavitation will influence the
potential for and magnitude of cavitation.
S
Acoustic field parameters like output frequency, peak pulse
amplitudes, and perhaps pulse length are the primary
parameters affecting the onset of cavitation. These are
controllable by the operator through appropriate equipment
selections.
Although it is generally accepted that no harmful biological
effects have been demonstrated at the frequency, intensity, and
exposure times used in diagnostic examinations, research into
the potential for harmful effects continues. The operator is
encouraged to survey the literature for future developments on
bioeffects and to become familiar with the references at the end
of this section.
LOGIQ 500 Advanced Reference Manual
2276614–100 Rev. 0