Medical diathermy is based on the use of high-frequency currents for the generation of heat in the tissues of the body for therapeutic purposes. The frequencies of the currents used are sufficiently high so that nerves or muscles are not stimulated. The intensity used is sufficiently low so that the temperature developed in the tissue is below that required to destroy the tissue or impair its vitality. The high-frequency currents used for diathermy can be applied locally for the purpose of heating the superficial and deep tissues.
Medical diathermy can be classified in the following 3 main divisions, based on differences in wavelengths and on the sources of the high-frequency current: (1) microwave diathermy; (2) short-wave diathermy and (3) long-wave diathermy. The table indicates the range and frequencies of wavelengths employed in the various divisions of the electromagnetic spectrum as it applies to diathermy. The Federal Communications Commission has assigned