Thermopulse is medical short wave diathermy equipment which generates radio frequency energy (high frequency at 27.12 MHz) in the form of intentional electromagnetic radiation for treatment of various pathologies. This kind of therapeutic heating has become popular because the high frequency currents can penetrate more deeply into the tissues showing superior advantages when compared with other methods which heat the tissues superficially.
THERMOPULSE short wave diathermy is produced by the application of the electromagnetic energy through the corporal tissues. The shortwave diathermy equipment consists of a circuit generator of sinusoidal wave which produces a current with a frequency of 27.12 MHz and a resonant circuit which can be tuned to exactly the same frequency. THERMOPULSE produces electrical and magnetic fields with high-frequency oscillating currents that produce the electromagnetic field generating physiological effects and therapeutic benefits. In these frequencies, the electromagnetic energy is converted into thermal energy by induction of circulating currents in insulating tissue. The heating effect produced by short wave diathermy helps the healing process generating deep heat into the tissues, resulting in numerous beneficial effects. The application mode of THERMOPULSE can be also pulsed, that is, it allows shots of electromagnetic energy to be emitted at pre-programmed time intervals minimizing the thermal effect to control the pain, edema and to speed the healing process.
Electromagnetic radiation used for electro medical equipment is within the range of RF used for communications. This way it could interfere with signals and, to avoid this interference, the Federal Communication Commission (FCC), which regulates all forms of telecommunication, has established specific frequencies for medical applications. The allowed ranges are centered in 13,56 MHz, 27,12 MHz and 40,68 MHz. The frequency of 27.12MHz is the most used because it has the widest range and, in addition, it is the easiest and the least expensive to be built, therefore, it is the most studied.
Differences between capacitive short waves, inductive and microwaves and their potential of heating tissues:
Diathermy applicators in capacitive plates are made of metal encased in plastic compartment or carbon rubber electrodes that are located in felt blocks.
A high frequency alternating current passes from one board to the other through the patient, producing an electric field and a current flow in the body tissue which is between the plates. As the current passes through the tissue, the charged particles oscillate causing an increase in the tissue temperature.
In inductive diathermy applicators, the amount of heat generated in a tissue area depends on the strength and current density and the highest heating occurs in tissues with the highest conductivity, such as the muscles. As the current always goes through the path with least resistance and because of that when a type of capacitive plate applicator is used, the current is generally concentrated on the tissue surface and does not penetrate so effectively in deeper tissues if these tissues are slightly conductive, such as subcutaneous fat.
Thus, the capacitive plates generally produce more heat into the skin and less heat into the deeper structures, in contrast to inductive applicators which heat the deepest structures with effectiveness because the incidence of the magnetic field can reach greater penetration to induce the electric field and the current within the target tissue.
In this same context, microwave diathermy equipment produces a high frequency alternating current in an antenna. This alternating current produces an electromagnetic field which is differentiated through the tissue by a encircled curve reflection near the antenna. Diathermy equipment is useful when only small areas of tissue are involved. Microwaves produce more heat in the tissues with high electric conductivity (muscles); however this radiation penetrates less deeply than the inductive short wave diathermy.