Output Power; Penetration Of Ultrasound Waves; Coupling - Dynatronics Dynatron 850 Plus Service Manual

Burns can be avoided as long as the treatment causes no pain, tingling, excess heat or aching
(for patients with normal skin sensation). Use sufficient coupling agent and make sure there
are no bubbles in the gel. When treating in water, clear the bubbles off the soundhead and off
the patient's skin.
An uncalibrated or faulty ultrasound unit can cause shear waves and standing waves that can
also cause burns.

Output Power

Higher output levels have a greater potential for patient discomfort. Output power may be
reduced by simply choosing a lower watt setting. Output power is also effectively reduced by
selecting a pulsed duty cycle.

Penetration of Ultrasound Waves

The correct frequency should be selected for the depth of penetration desired: 1 MHz
provides deeper penetration, 2 MHz provides moderate penetration, and 3 MHz provides
more shallow penetration. The amount of penetration needed is determined by the density of
tissue and the depth of the site to be treated. Care should be taken to select a penetration
level that does not cause periosteal (bone) pain.

Coupling

The term "coupling" refers to the ability to deliver ultrasonic waves from the soundhead to
the skin surface with as little impedance or dissipation of power as possible. The best
coupling is achieved when the ultrasound head has full, direct contact over the treatment site
or when the treatment site and soundhead are separated only by a substance that provides
excellent conductance.
For example, water is an excellent conductor of ultrasonic waves. Therefore, ultrasound
treatment in water provides excellent coupling.
Air is a poor conductor of ultrasonic waves. If any part of the soundhead is exposed to air
during the treatment, coupling is decreased. When treating a patient outside of water, the
soundhead must maintain good contact with the patient skin at all times. In addition, a good
conductive gel or lotion should be used to ensure the best possible coupling. Many such
products are commercially available specifically for ultrasound therapy.
Since air is a poor conductor of ultrasound, it is not advisable to introduce air into the water
during an ultrasound treatment. The air bubbles in a whirlpool, for example, can decrease the
effective ultrasound therapy to the patient.
Dynatron 850plus & 550plus
®
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Ultrasound Technical Information