Ultrasound And Its Applications - Bowles UW-7 User Manual

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Ultrasound and Its Applications

Human perception of sound waves is limited to frequencies of fewer than 20,000
vibrations per second. Higher frequency vibrations — between 0.7 and 3.3 MHz —
are used for ultrasound therapy. (Most ultrasound equipment produces an output of
between 1 and 3.3 MHz.)
An ultrasound unit produces electrical oscillations at a specified frequency that cause
the transducer in the ultrasound applicator to generate sound waves. The resulting
ultrasonic radiation is transmitted from the ultrasound applicator, or treatment head,
through a coupling medium, to the patient's tissue.
Therapeutic Use of Ultrasound
The therapeutic use of ultrasonic energy is accepted worldwide, and most modern
hospitals and clinics have ultrasound devices in their physical therapy
departments.
Ultrasound therapy is primarily used in the treatment of sports-related injuries.
Another common use is the treatment of circulatory disorders and rheumatic
diseases of the musculoskeletal system and peripheral nerves. Ultrasound has
been found to be extremely effective in treating body areas with a great deal of
scar tissue.
Physiological Effects of Ultrasound Therapy
It is well documented that ultrasound therapy heals because of thermal,
mechanical, and chemical effects. *
Thermal effects include deep tissue heating at depths to 5 cm or more. The ther-
mal effects of ultrasound differ from diathermy (the use of electrical impulses to
produce generalized vasodilation) in that the ultrasound beam heats only a small
tissue area that approximates the cross-section of the beam. This heating effect is
concentrated in muscles, ligaments, nerves, bones, and where the ultrasound beam
crosses from one type of tissue to another.
The mechanical effects are best described as micro massage, a deep stirring action
within the tissue. The benefit of this action is an increased circulation to the
damaged tissue. In addition, ultrasound is capable of separating collagen fibers
from one another and of changing the tensile strength of tendons, thereby
increasing their extensibility.
* Physical Agents for Physical Therapists, Second Edition, James E. Griffin and Terence Karselis, Charles C. Thomas
Publishing Co., 1992.
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