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Ultrasound has been a part of medical practice since the early 50s and remains a popular and proven method for diagnosing a wide range of clinical problems.
There are various therapeutic ultrasound devices. The list starts with small portable devices, often used in cosmetology, and ends with whole complexes – multimodal machines that use ultrasound in medical practice.
Ultrasonic devices differ in their technical characteristics, although their purpose is the same. However, more powerful devices can pinpoint existing problems, speeding up patient care.
What is an ultrasound therapy machine?
The operation of the device is based on ultrasonic frequencies, which affect the patient’s body. Ultrasound is a form of mechanical energy, which means that this method does not belong to electrotherapy, but falls into the group of electrophysical ones. Mechanical vibration as frequency increases is known as sound energy.
The normal sound range for humans is 16 Hz to 15-20 Hz (in children and young adults).
Above the upper limit, mechanical vibration is known as ultrasonic. Frequencies used in therapy are typically between 1,0 and 3,0 MHz (1 MHz = 1 million cycles per second).
How do ultrasound machines work?
The basis of ultrasound therapy is the impact of waves. Waves affect body tissues in two ways – thermal and mechanical. Sound waves are long-term waves that do two things: compress and propagate. Particles of material, when exposed to a sound wave, will oscillate around a fixed point, and not move with the wave itself. As the energy in the sound wave is transferred to the material, it causes its particles to vibrate.
Obviously, any increase in molecular vibration in tissue can generate heat, and ultrasound can be used to produce thermal changes in tissues. In addition to thermal changes, tissue vibration appears to have effects that are generally considered non-thermal in nature. As the machine wave passes through the material (tissues), the energy levels within the wave will decrease as it is transmitted.
What is the difference between ultrasonic therapy devices?
There are several criteria by which these devices differ:
- frequency of ultrasonic waves;
- wave range;
- transmission speed.
Typically, these three indicators determine the power and novelty of the device, as well as its ability to provide a therapeutic effect. The frequency indicates the number of times a particle experiences a complete contraction/expansion cycle in 1 second. Usually 1 or 3 MHz (although there are devices that operate in the kHz-cm range).
The range or wavelength is the second indicator that shows the distance between two equivalent points in a particular medium. In “medium tissue”, the wavelength of 1 MHz is 1,5 mm, and 3 MHz is 0,5 mm. The speed with which it passes through the tissue is also important. In a saline solution, the wave speed is approximately 1500 m/s compared to approximately 350 m/s in air (sound waves can travel faster in a denser medium).
These three factors are related, but are not appropriate for the examination and treatment of all tissue types. Most often, averages are used. The doctor who conducts the examination selects the special parameters of the device individually for each patient.
Typical frequencies in therapeutic equipment are 1 and 3 MHz, although additional frequencies are produced on some devices (for example, 0,75 and 1,5 MHz), and individual ultrasonic devices operate within a few tens of kHz (typically 40-50 Hz – more lower frequency than conventional apparatus, but still beyond human hearing).
To whom is ultrasound contraindicated?
Like any other treatment, ultrasound therapy can be contraindicated for a number of reasons. Since ultrasound has a very strong effect on the body, “reinsurance” will never be superfluous. In order not to harm your body, you must first consult with your doctor and discuss all the possible consequences of future therapy.
Women should be especially careful during pregnancy, as powerful ultrasonic waves can harm the fetus. This does not apply to conventional ultrasound examinations. Every patient should understand that ultrasound therapy and diagnostics are two different things.
The first is high power waves for treatment, the second is a light effect that helps to detect an existing problem. Below is a complete list of contraindications for ultrasound treatment.
You will not be able to receive therapy if you have one of the following:
- pregnancy (do not expose the embryo or fetus to therapeutic level ultrasonic waves when treating the uterus during pregnancy);
- malignant tumor (do not treat tissue that is currently considered malignant);
- tissues in which bleeding occurs or those that are prone to bleeding;
- significant vascular anomalies, including deep vein thrombosis, embolism, and severe arteriosclerosis/atherosclerosis.
When treating with ultrasound, precautions must be taken. This guarantees a more effective and safer treatment. Always use the lowest intensity that produces the therapeutic effect. Make sure the applicator is moved during treatment (speed and direction are not a problem).
Ask your doctor to tell you about this method again. You must be aware of the nature of the treatment and the expected outcome. If heat treatment is contemplated, ensure that all contraindications have been considered.
Caution is advised in the immediate vicinity of a pacemaker or other implanted electronic device.
Continuous ultrasound is considered unreasonable over metal implants – this is also worth considering before starting treatment.
The effectiveness of the ultrasound therapy device
One of the therapeutic effects for which ultrasound is used is to improve tissue healing. It is expected that applying the action of the device to damaged tissues, among other things, will accelerate the rate of healing and improve the quality of tissue repair. The therapeutic effects of an ultrasound machine are thermal and non-thermal.
In thermal mode, the devices are most efficient at heating dense collagen tissues and require a relatively high intensity, preferably continuous, to achieve this effect.
Many therapies focus on the thermal efficiency of ultrasound, and therefore it can be effectively applied when the appropriate dose is selected (continuous mode >0,5 W cm-2). It is too general to assume that there may be either thermal or non-thermal effects when using a particular treatment. The dominant effect will be influenced by the treatment parameters, especially the method of application, i.e. pulsed or continuous therapy.
The effect is not always positive. Failure to comply with the rules for using the device, violation of the dose of ultrasound or its parameters can lead to undesirable consequences. The appearance of reversible blood cells is manifested in small blood vessels if a standing wave occurs during treatment with a reflector, for example, the surface of soft tissue/bone when using a stationary applicator. The continuous movement of the processing head reduces this danger.
Before starting the procedure, the medical officer must inspect the device. It is necessary to set its correct parameters: frequency, intensity, time, pulse parameters. It is important to prepare the surface of the body that is being treated. Also, the doctor must conduct this procedure in such a way as to eliminate any immediate or adverse effects.