Medical applications of radio frequency

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Medical applications of radio frequency (RF) energy, in the form of electromagnetic waves (radio waves) or electrical currents, have existed for over 125 years, [1] and now include diathermy, hyperthermy treatment of cancer, electrosurgery scalpels used to cut and cauterize in operations, and radiofrequency ablation. [2] Magnetic resonance imaging (MRI) uses radio frequency waves to generate images of the human body. [3]

Contents

Radio frequencies at non-ablation energy levels are commonly used as a part of aesthetic treatments that can tighten skin, reduce fat by lipolysis and also apoptosis, [4] or promote healing. [5]

RF diathermy is a medical treatment that uses RF induced heat as a form of physical therapy and in surgical procedures. It is commonly used for muscle relaxation. It is also a method of heating tissue electromagnetically for therapeutic purposes in medicine. Diathermy is used in physical therapy to deliver moderate heat directly to pathologic lesions in the deeper tissues of the body. Surgically, the extreme heat that can be produced by diathermy may be used to destroy neoplasms, warts, and infected tissues, and to cauterize blood vessels to prevent excessive bleeding. The technique is particularly valuable in neurosurgery and surgery of the eye. Diathermy equipment typically operates in the short-wave radio frequency (range 1–100 MHz) or microwave energy (range 434–915 MHz).[ citation needed ]

Pulsed electromagnetic field therapy (PEMF) is a medical treatment that purportedly helps to heal bone tissue reported in a recent NASA study. This method usually employs electromagnetic radiation of different frequencies – ranging from static magnetic fields, through extremely low frequencies (ELF) to higher radio frequencies (RF) administered in pulses.[ citation needed ]

History

The idea that high-frequency electromagnetic currents could have therapeutic effects was explored independently around the same time (1890–91) by French physician and biophysicist Jacques Arsene d'Arsonval and Serbian American engineer Nikola Tesla. [6] [7] [8] d'Arsonval had been studying medical applications for electricity in the 1880s and performed the first systematic studies in 1890 of the effect of alternating current on the body, and discovered that frequencies above 10 kHz did not cause the physiological reaction of electric shock, but warming. [7] [8] [9] [10] He also developed the three methods that have been used to apply high-frequency current to the body: contact electrodes, capacitive plates, and inductive coils. [8] Nikola Tesla first noted around 1891 the ability of high-frequency currents to produce heat in the body and suggested its use in medicine. [6]

By 1900 application of high-frequency current to the body was used experimentally to treat a wide variety of medical conditions in the quack medical field of electrotherapy . In 1899 Austrian chemist von Zaynek determined the rate of heat production in tissue as a function of frequency and current density, and first proposed using high-frequency currents for deep heating therapy. [7] In 1908 German physician Karl Franz Nagelschmidt coined the term diathermy, and performed the first extensive experiments on patients. [8]

Until the 1920s noisy spark-discharge Tesla coil and Oudin coil machines were used. These were limited to frequencies of 0.1 – 2 MHz, called "longwave" diathermy. The current was applied directly to the body with contact electrodes, which could cause skin burns. In the 1920s the development of vacuum tube machines allowed frequencies to be increased to 10 – 300 MHz, called "shortwave" diathermy. The energy was applied to the body with inductive coils of wire or capacitive plates insulated from the body, which reduced the risk of burns. By the 1940s microwaves were being used experimentally. In 1926 William T. Bovie discovered that RF currents applied to a scalpel could cut and cauterize tissue in medical operations, and electrosurgery generators or "Bovies" have been used in surgery ever since. [11]

See also

Related Research Articles

The ISM radio bands are portions of the radio spectrum reserved internationally for industrial, scientific, and medical (ISM) purposes, excluding applications in telecommunications. Examples of applications for the use of radio frequency (RF) energy in these bands include RF heating, microwave ovens, and medical diathermy machines. The powerful emissions of these devices can create electromagnetic interference and disrupt radio communication using the same frequency, so these devices are limited to certain bands of frequencies. In general, communications equipment operating in ISM bands must tolerate any interference generated by ISM applications, and users have no regulatory protection from ISM device operation in these bands.

<span class="mw-page-title-main">Microwave</span> Electromagnetic radiation with wavelengths from 1 m to 1 mm

Microwave is a form of electromagnetic radiation with wavelengths shorter than other radio waves but longer than infrared waves. Its wavelength ranges from about one meter to one millimeter, corresponding to frequencies between 300 MHz and 300 GHz, broadly construed. A more common definition in radio-frequency engineering is the range between 1 and 100 GHz, or between 1 and 3000 GHz . The prefix micro- in microwave is not meant to suggest a wavelength in the micrometer range; rather, it indicates that microwaves are small, compared to the radio waves used in prior radio technology.

<span class="mw-page-title-main">Tesla coil</span> Electrical resonant transformer circuit invented by Nikola Tesla

A Tesla coil is an electrical resonant transformer circuit designed by inventor Nikola Tesla in 1891. It is used to produce high-voltage, low-current, high-frequency alternating-current electricity. Tesla experimented with a number of different configurations consisting of two, or sometimes three, coupled resonant electric circuits.

<span class="mw-page-title-main">Electromagnetic radiation and health</span> Aspect of public health

Electromagnetic radiation can be classified into two types: ionizing radiation and non-ionizing radiation, based on the capability of a single photon with more than 10 eV energy to ionize atoms or break chemical bonds. Extreme ultraviolet and higher frequencies, such as X-rays or gamma rays are ionizing, and these pose their own special hazards: see radiation poisoning. The field strength of electromagnetic radiation is measured in volts per meter (V/m).

Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around 20 kHz to around 300 GHz. This is roughly between the upper limit of audio frequencies and the lower limit of infrared frequencies, and also encompasses the microwave range, though other definitions treat microwaves as a separate band from RF. These are the frequencies at which energy from an oscillating current can radiate off a conductor into space as radio waves, so they are used in radio technology, among other uses. Different sources specify different upper and lower bounds for the frequency range.

<span class="mw-page-title-main">Radio wave</span> Type of electromagnetic radiation

Radio waves are a type of electromagnetic radiation with the lowest frequencies and the longest wavelengths in the electromagnetic spectrum, typically with frequencies below 300 gigahertz (GHz) and wavelengths greater than 1 millimeter, about the diameter of a grain of rice. Like all electromagnetic waves, radio waves in a vacuum travel at the speed of light, and in the Earth's atmosphere at a slightly slower speed. Radio waves are generated by charged particles undergoing acceleration, such as time-varying electric currents. Naturally occurring radio waves are emitted by lightning and astronomical objects, and are part of the blackbody radiation emitted by all warm objects.

Cauterization is a medical practice or technique of burning a part of a body to remove or close off a part of it. It destroys some tissue in an attempt to mitigate bleeding and damage, remove an undesired growth, or minimize other potential medical harm, such as infections when antibiotics are unavailable.

<span class="mw-page-title-main">Wireless power transfer</span> Transmission of electrical energy without wires as a physical link

Wireless power transfer (WPT), wireless power transmission, wireless energy transmission (WET), or electromagnetic power transfer is the transmission of electrical energy without wires as a physical link. In a wireless power transmission system, an electrically powered transmitter device generates a time-varying electromagnetic field that transmits power across space to a receiver device; the receiver device extracts power from the field and supplies it to an electrical load. The technology of wireless power transmission can eliminate the use of the wires and batteries, thereby increasing the mobility, convenience, and safety of an electronic device for all users. Wireless power transfer is useful to power electrical devices where interconnecting wires are inconvenient, hazardous, or are not possible.

Diathermy is electrically induced heat or the use of high-frequency electromagnetic currents as a form of physical therapy and in surgical procedures. The earliest observations on the reactions of the human organism to high-frequency electromagnetic currents were made by Jacques Arsene d'Arsonval. The field was pioneered in 1907 by German physician Karl Franz Nagelschmidt, who coined the term diathermy from the Greek words διά dia and θέρμη thermē, literally meaning "heating through".

<span class="mw-page-title-main">Jacques-Arsène d'Arsonval</span>

Jacques-Arsène d'Arsonval was a French physician, physicist and inventor of the moving-coil D'Arsonval galvanometer and the thermocouple ammeter. D'Arsonval was an important contributor to the emerging field of electrophysiology, the study of the effects of electricity on biological organisms, in the nineteenth century.

<span class="mw-page-title-main">Oudin coil</span> Resonant transformer circuit

An Oudin coil, also called an Oudin oscillator or Oudin resonator, is a resonant transformer circuit that generates very high voltage, high frequency alternating current (AC) electricity at low current levels, used in the obsolete forms of electrotherapy around the turn of the 20th century. It is very similar to the Tesla coil, with the difference being that the Oudin coil was connected as an autotransformer. It was invented in 1893 by French physician Paul Marie Oudin as a modification of physician Jacques Arsene d'Arsonval's electrotherapy equipment and used in medical diathermy therapy as well as quack medicine until perhaps 1940. The high voltage output terminal of the coil was connected to an insulated handheld electrode which produced luminous brush discharges, which were applied to the patient's body to treat various medical conditions in electrotherapy.

<span class="mw-page-title-main">Dielectric heating</span> Heating using radio waves

Dielectric heating, also known as electronic heating, radio frequency heating, and high-frequency heating, is the process in which a radio frequency (RF) alternating electric field, or radio wave or microwave electromagnetic radiation heats a dielectric material. At higher frequencies, this heating is caused by molecular dipole rotation within the dielectric.

Paul Marie Oudin (1851–1923) was a French physician and medical researcher. He was born, and later died, in Épinal. He conducted research in the Victorian era medical field of high frequency electrotherapy, the application of radio frequency electric currents to the body, and collaborated with the founder of the field, pioneering physiologist and biophysicist Dr. Jacques Arsene d'Arsonval. In 1893 he modified d'Arsonval's electrotherapy equipment by the addition of a wire coil resonator to produce higher potentials, inventing the Oudin coil. This device, very similar to a Tesla coil, could produce very high voltages from several hundred thousand to a million volts. In use, the brush discharges from a pointed electrode attached to the high voltage terminal of the coil would be played over various parts of the body to treat a variety of medical conditions. The Oudin coil was used in electrotherapy and diathermy through the 1920s.

Bioelectromagnetics, also known as bioelectromagnetism, is the study of the interaction between electromagnetic fields and biological entities. Areas of study include electromagnetic fields produced by living cells, tissues or organisms, the effects of man-made sources of electromagnetic fields like mobile phones, and the application of electromagnetic radiation toward therapies for the treatment of various conditions.

<span class="mw-page-title-main">Electrosurgery</span> Use of high-frequency, alternating polarity, electrical current in medical operations

Electrosurgery is the application of a high-frequency alternating polarity, electrical current to biological tissue as a means to cut, coagulate, desiccate, or fulgurate tissue. Its benefits include the ability to make precise cuts with limited blood loss. Electrosurgical devices are frequently used during surgical operations helping to prevent blood loss in hospital operating rooms or in outpatient procedures.

Georges Lakhovsky was a Russian-French engineer, author, and inventor.

Pulsed radiofrequency is the technique whereby radio frequency (RF) oscillations are gated at a rate of pulses (cycles) per second (one cycle per second is known as a hertz (Hz)). Radio frequency energies occupy 1.0×104 Hz to 3.0×1011 Hz of the electromagnetic spectrum. Radio frequency electromagnetic energy is routinely produced by RF electrical circuits connected to a transducer, usually an antenna.

Microwave burns are burn injuries caused by thermal effects of microwave radiation absorbed in a living organism.

<span class="mw-page-title-main">Non-ionizing radiation</span> Harmless low-frequency radiation

Non-ionizingradiation refers to any type of electromagnetic radiation that does not carry enough energy per quantum to ionize atoms or molecules—that is, to completely remove an electron from an atom or molecule. Instead of producing charged ions when passing through matter, non-ionizing electromagnetic radiation has sufficient energy only for excitation. Non-ionizing radiation is not a significant health risk. In contrast, ionizing radiation has a higher frequency and shorter wavelength than non-ionizing radiation, and can be a serious health hazard: exposure to it can cause burns, radiation sickness, many kinds of cancer, and genetic damage. Using ionizing radiation requires elaborate radiological protection measures, which in general are not required with non-ionizing radiation.

<span class="mw-page-title-main">History of the Tesla coil</span> An electric circuit which produces very high voltage alternating current

Nikola Tesla patented the Tesla coil circuit on April 25, 1891. and first publicly demonstrated it May 20, 1891 in his lecture "Experiments with Alternate Currents of Very High Frequency and Their Application to Methods of Artificial Illumination" before the American Institute of Electrical Engineers at Columbia College, New York. Although Tesla patented many similar circuits during this period, this was the first that contained all the elements of the Tesla coil: high voltage primary transformer, capacitor, spark gap, and air core "oscillation transformer".

References

  1. ↑ Ruey J. Sung & Michael R. Lauer (2000). Fundamental approaches to the management of cardiac arrhythmias. Springer. p. 153. ISBN   978-0-7923-6559-4. Archived from the original on 2015-09-05.
  2. ↑ Melvin A. Shiffman; Sid J. Mirrafati; Samuel M. Lam; Chelso G. Cueteaux (2007). Simplified Facial Rejuvenation. Springer. p. 157. ISBN   978-3-540-71096-7.
  3. ↑ Bethge, K. (2004-04-27). Medical Applications of Nuclear Physics. Springer Science & Business Media. ISBN   9783540208051. Archived from the original on 2018-05-01.
  4. ↑ McDaniel, David; Lozanova, Paula (2015–2016). "Human Adipocyte Apoptosis Immediately Following High Frequency Focused Field Radio Frequency: Case Study". Journal of Drugs in Dermatology. 14 (6): 622–623. ISSN   1545-9616. PMID   26091389.
  5. ↑ "Noninvasive Radio Frequency for Skin Tightening and Body Contouring, Frontline Medical Communications, 2013" (PDF). skinandallergynews.com. Archived from the original (PDF) on 29 October 2013. Retrieved 16 March 2018.
  6. 1 2 Rhees, David J. (July 1999). "Electricity – "The greatest of all doctors": An introduction to "High Frequency Oscillators for Electro-therapeutic and Other Purposes"". Proceedings of the IEEE. 87 (7). Inst. of Electrical and Electronic Engineers: 1277–1281. doi:10.1109/jproc.1999.771078.
  7. 1 2 3 Ho, Mae-Wan; Popp, Fritz Albert; Warnke, Ulrich (1994). Bioelectrodynamics and Biocommunication. World Scientific. pp. 10–11. ISBN   978-9810216658.
  8. 1 2 3 4 J. W. Hand,"Biophysics and Technology of Electromagnetic Hyperthermia" in Gautherie, Michel, Ed. (2012). Methods of External Hyperthermic Heating. Springer Science & Business Media. pp. 4–8. ISBN   978-3642746338.{{cite book}}: CS1 maint: multiple names: authors list (link)
  9. ↑ D'Arsonval, A. (August 1893). "Physiological action of currents of great frequency". Modern Medicine and Bacteriological World. 2 (8). Modern Medicine Publishing Co.: 200–203. Retrieved November 22, 2015., translated by J. H. Kellogg
  10. ↑ Kovács, Richard (1945). Electrotherapy and Light Therapy, 5th Ed. Philadelphia: Lea and Febiger. pp. 187–188, 197–200.
  11. ↑ Carr, Joseph J. (May 1990). "Early radio transmitters" (PDF). Popular Electronics. 7 (5): 43–46. Retrieved 21 March 2018.
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