infrared radiation

infrared radiation,

electromagnetic radiationelectromagnetic radiation,
energy radiated in the form of a wave as a result of the motion of electric charges. A moving charge gives rise to a magnetic field, and if the motion is changing (accelerated), then the magnetic field varies and in turn produces an electric field.
..... Click the link for more information. having a wavelength in the range from c.75 × 10⁻⁶ cm to c.100,000 × 10⁻⁶ cm (0.000075–0.1 cm). Infrared rays thus occupy that part of the electromagnetic spectrumspectrum,
arrangement or display of light or other form of radiation separated according to wavelength, frequency, energy, or some other property. Beams of charged particles can be separated into a spectrum according to mass in a mass spectrometer (see mass spectrograph).
..... Click the link for more information. with a frequency less than that of visible lightlight,
visible electromagnetic radiation. Of the entire electromagnetic spectrum, the human eye is sensitive to only a tiny part, the part that is called light. The wavelengths of visible light range from about 350 or 400 nm to about 750 or 800 nm.
..... Click the link for more information. and greater than that of most radio waves, although there is some overlap. The name infrared means "below the red," i.e., beyond the red, or lower-frequency (longer wavelength), end of the visible spectrum. Infrared radiation is thermal, or heatheat,
nonmechanical energy in transit, associated with differences in temperature between a system and its surroundings or between parts of the same system. Measures of Heat
..... Click the link for more information. , radiation. It was first discovered in 1800 by Sir William Herschel, who was attempting to determine the part of the visible spectrum with the minimum associated heat in connection with astronomical observations he was making. In 1847, A. H. L. Fizeau and J. B. L. Foucault showed that infrared radiation has the same properties as visible light, being reflected, refracted, and capable of forming an interferenceinterference,
in physics, the effect produced by the combination or superposition of two systems of waves, in which these waves reinforce, neutralize, or in other ways interfere with each other.
..... Click the link for more information. pattern. Infrared radiation is typically produced by objects whose temperaturetemperature,
measure of the relative warmth or coolness of an object. Temperature is measured by means of a thermometer or other instrument having a scale calibrated in units called degrees. The size of a degree depends on the particular temperature scale being used.
..... Click the link for more information. is above 10&degK;. There are many applications of infrared radiation. A number of these are analogous to similar uses of visible light. Thus, the spectrum of a substance in the infrared range can be used in chemical analysis much as the visible spectrum is used. Radiation at discrete wavelengths in the infrared range is characteristic of many molecules. The temperature of a distant object can also be determined by analysis of the infrared radiation from the object. Radiometers operating in the infrared range serve as the basis for many instruments, including heat-seeking devices in missiles and devices for spotting and photographing persons and objects in the dark or in fog. Medical uses of infrared radiation range from the simple heat lamp to the technique of thermal imaging, or thermographythermography
, contact photocopying process that produces a direct positive image and in which infrared rays are used to expose the copy paper. In a specially designed machine the original is placed in contact with a copy paper containing a heat-sensitive substance.
..... Click the link for more information. . A thermograph of a person can show areas of the body where the temperature is much higher or lower than normal, thus indicating some medical problem. Thermography has also been used in industry and other applications. Some lasers produce infrared radiation. A recent development has been the expansion of research in infrared astronomyinfrared astronomy,
study of celestial objects by means of the infrared radiation they emit, in the wavelength range from about 1 micrometer to about 1 millimeter. All objects, from trees and buildings on the earth to distant galaxies, emit infrared (IR) radiation.
..... Click the link for more information. ; infrared sensors are sent aloft in balloons, rockets, and satellites to study the infrared radiation reaching the earth from other parts of the solar system and beyond.

Infrared radiation

Electromagnetic radiation in which wavelengths lie in the range from about 1 micrometer to 1 millimeter. This radiation therefore has wavelengths just a little longer than those of visible light and cannot be seen with the unaided eye. The radiation was discovered in 1800 by William Herschel.

An infrared source can be described by the spectral distribution of power emitted by an ideal body (a blackbody curve). This distribution is characteristic of the temperature of the body. A real body is related to it by a radiation efficiency factor or emissivity which is the ratio at every wavelength of the emission of a real body to that of a blackbody under identical conditions. The illustration shows curves for these ideal blackbodies radiating at a number of different temperatures. The higher the temperature, the greater the total amount of radiation. See Emissivity

Radiation from blackbodies at different temperatures, shown on a logarithmic scale

Infrared detectors are based either on the generation of a change in voltage due to a change in the detector temperature resulting from the power focused on it, or on the generation of a change in voltage due to some photon-electron interaction in the detector material. This latter effect is sometimes called the internal photoelectric effect.

Infrared techniques have been applied in military, medical, industrial, meteorological, ecological, forestry, agricultural, chemical, and other disciplines. Weather satellites use infrared imaging devices to map cloud patterns and provide the imagery seen in many weather reports. Infrared imaging devices have also been used for breast cancer screening and other medical diagnostic applications. In most of these applications, the underlying principle is that pathology produces inflammation, and these locations of increased temperature can be found with an infrared imager. Airborne infrared imagers have been used to locate the edge of burning areas in forest fires.

infrared radiation

Electromagnetic radiation lying between the radio and the visible bands of the electromagnetic spectrum. The wavelengths range from about 0.8 micrometer (μm) to about 1000 μm. The definitions of the regions of the infrared are a little arbitrary, but are roughly as follows:

near-infrared : 0.8 to 8 μm

mid-infrared : 8.0 to 30 μm

far-infrared : 30 to 300 μm

The region around 8–13 μm has been described as far-infrared by some astronomers. Radiation above 300 μm is now called submillimeter radiation.

Infrared Radiation

electromagnetic radiation that occupies the spectral region between the red end of visible light (with a wavelength of λ = 0.74 microns [μ]) and shortwave radiation (λ ∼ 1–2 mm). The infrared region of the spectrum is usually subdivided conditionally into the near (λ ranges from 0.74 to 2.5 μ), middle, or intermediate (2.5−50μ), and far (50—2,000 μ) infrared regions.

Infrared radiation was discovered in 1800 by the British scientist W. Herschel, who observed an increase in the temperature of a thermometer placed outside the red end of the sun’s spectrum obtained with the aid of a prism (see Figure 1); that is, in the invisible part of the spectrum. It was proved in the 19th century that infrared radiation conforms to the laws of optics and consequently is of the same nature as visible light. In 1923 the Soviet physicist A. A. Glagoleva-Arkad’eva obtained radio waves with λ ∼ 80 μ, that is, waves that corresponded to the infrared range of wavelengths. Thus it was proved experimentally that there exists a continuous transition from visible radiation to infrared and radio-wave radiation, and consequently all are electromagnetic in nature.

Figure 1. Herschel’s experiment. A thermometer placed beyond the red part of the sun’s spectrum showed a higher temperature than did the control thermometers placed to the side.

The spectrum of infrared radiation, like that of visible and ultraviolet radiation, may consist of individual lines or bands or may be continuous, depending on the nature of the source of the infrared radiation. Excited atoms or ions emit infrared line spectra. For example, mercury vapors on electrical discharge emit a number of narrow lines in the interval 1.014–2.326 μ, and hydrogen atoms emit a number of lines in the interval 0.95–7.40 μ. Excited molecules emit infrared band spectra owing to their oscillations and rotations. Vibration and vibration-rotation spectra lie primarily in the middle infrared region and pure rotation spectra lie in the far infrared region. Thus, for example, in the radiation spectrum of a gas flame, a band at about 2.7 μ, emitted by water molecules, and bands at λ ≈ 2.7 μ. and λ ≈ 4.2 μ, emitted by molecules of carbon dioxide, can be observed. Heated solid and liquid, bodies emit a continuous infrared spectrum. A heated solid radiates in a very broad range of wavelengths. At low temperatures (below 800°K) the radiation of a heated solid lies almost entirely in the infrared region, and such a body seems to be dark. As the temperature rises, the part of the radiation in the visible region increases and the body first appears to be dark red, then red, then yellow, and, finally, at high temperatures (above 5000°K), white. Here, both the total energy of radiation and the energy of the infrared radiation rise.

Figure 2. Curve of atmospheric transmission in the region 0.6−14 μ. The bands are transparent “windows”: 2.0−2.5 μ, 3.2−4.2 μ, 4.5−5.2 μ, 8.0−13.5 μ. The absorption bands with maximums at λ = 0.93, 1.13, 1.40, 1.87, and 2.74 μ belong to water vapor; at λ = 2.7 and 4.26 μ. to carbon dioxide gas; and at λ = 9.5 to ozone.

Optical properties. The optical properties of substances (transparency, reflection coefficient, index of refraction) in the infrared region of the spectrum generally differ significantly from the optical properties in the visible and ultraviolet regions. Many substances that are transparent in the visible region prove to be opaque in certain areas of infrared radiation, and vice versa. For example, a layer of water several centimeters thick is opaque to infrared radiation for λ > 1 μ (therefore water is often used as a heat filter), and wafers of germanium and silicon, which are opaque in the visible region, are transparent in the infrared region (germanium for λ > 1.8 μ. and silicon for λ > 1.0 μ Black paper is transparent in the far infrared region. Substances that are transparent to infrared radiation and opaque in the visible region are used as light filters to isolate infrared radiation. A number of substances are transparent, even in thick layers (of several centimeters), over quite large regions of the infrared spectrum. Various optical components (such as prisms, lenses, and windows) of infrared devices are manufactured from such substances. For example, glass is transparent up to 2.7 μ, quartz to 4.0 μ and from 100 μ to 1,000 μ, rock salt to 15 μ., and cesium iodide to 55 μ. Polyethylene, paraffin, teflon, and diamond are transparent for λ > 100 μ. In most metals, the reflectivity is much higher for infrared radiation than for visible light and increases with the wavelength of the infrared radiation. For example, the reflection coefficient of Al, Au, Ag, and Cu reaches 98 percent when λ = 10 μ. Liquid and solid nonmetallic substances have selective reflection of infrared radiation in such a way that the position of reflection maximums depends on the chemical composition of the substance.

On passing through the earth’s atmosphere, infrared radiation is attenuated as a result of scattering and absorption. The nitrogen and oxygen in the air do not absorb infrared radiation and attenuate it only as a result of scattering, which, however, is much less for infrared radiation than for visible light. Water vapor, carbon dioxide, ozone, and other impurities present in the atmosphere selectively absorb infrared radiation. Water vapor, whose absorption bands lie throughout virtually the entire infrared region of the spectrum, and carbon dioxide in the middle infrared region absorb infrared radiation with particular intensity. In the ground layers, there is only a small number of “windows” transparent to infrared radiation in the middle infrared region (Figure 2). The presence in the atmosphere of suspended particles—smoke, dust, and fine droplets of water (mist or fog)—leads to the additional attenuation of infrared radiation as a result of its scattering on these particles. The extent of scattering depends on the correlation between the size of the particles and the wavelength of the infrared radiation. When the particles are small (distance fog), infrared radiation is scattered less than visible radiation (this fact is utilized in infrared photography), but when the drops are large (as in the case of a dense fog), the infrared radiation is scattered just as strongly as the visible radiation.

Sources. The sun, about 50 percent of whose radiation lies in the infrared region, is a powerful source of infrared radiation. Infrared radiation accounts for a large part (70–80 percent) of the radiated energy of incandescent lamps with a tungsten filament (Figure 3). For photography in the dark and in some infrared sight equipment, the illuminating lamps are fitted with an infrared light filter, which passes only infrared radiation. A carbon electric arc with a temperature of ∼3900°K, whose radiation is close to the radiation of a blackbody, as well as various gas discharge tubes (pulse and continuous-action) are powerful sources of infrared radiation. Spirals of nichrome wire, heated to a temperature of ∼950°K, are used for radiative room heating. Such heaters are fitted with reflectors to provide better concentration of the infrared radiation. In scientific research, special sources of infrared radiation, such as tungsten ribbon filament lamps, Nernst lamps, globars, and high-pressure mercury lamps, are used, for example, to obtain infrared absorption spectra in different parts of the spectrum. The radiatioi of some optical quantum generators—lasers—also lies in the infrared region of the spectrum; for example, the radiation of a neodymium glass laser has a wavelength of 1.06 u.; the radiation of a neon-helium laser, 1.15μ. and 3.39μ; the radiation of a carbon-dioxide-gas laser, 10.6 μ; and the radiation of a InSb semiconductor laser, 5 μ.

Figure 3. Radiation curves of an ideal blackbody A and tungsten B at a temperature of 2450°K. Shaded area is tungsten’s radiation in the infrared region; the interval 0.40–0.74 μ is the visible region.

Infrared detectors are based on the conversion of the energy of infrared radiation into other types of energy that can be measured by ordinary methods. There are thermal and photoelectric infrared detectors. In the former, the absorbed infrared radiation effects an increase in the temperature of the heat-sensitive element of the detector, and this rise is registered. In photoelectric detectors, the absorbed infrared radiation leads to the appearance of or a change in an electric current or voltage. Photoelectric detectors, in contrast to thermal detectors, are selective, that is, sensitive only in a certain region of the spectrum. Special photographic films and plates—infrared plates—are also sensitive to infrared radiation (up to λ = 1.2 μ), and therefore photographs can be made in infrared radiation.

Applications. Infrared radiation finds broad application in scientific research, in the solution of a large number of practical problems, in the military, and elsewhere. The investigation of emission and absorption spectra in the infrared region is used in the study of the structure of the electron shell of atoms, for the determination of the structure of molecules, and for qualitative and quantitative analysis of mixtures of substances of complex molecular composition, such as engine fuel.

Because of the difference in the scattering, reflection, and transmission coefficients by substances in visible and infrared radiation, a photograph made by infrared radiation has a number of properties not possessed by an ordinary photograph. For example, details invisible in an ordinary photograph are often visible in infrared photographs.

In industry, infrared radiation is used to dry and heat materials and products upon irradiation and also to detect concealed flaws in products.

Special devices—image converters, in which the infrared image of an object at the photocathode, which is invisible to the eye, is converted into a visible image—have been developed on the basis of photocathodes that are sensitive to infrared radiation (for λ < 1.3 μ). Various infrared sight equipment (such as binoculars and sighting devices), which make it possible by irradiating the observed objects with infrared radiation from special sources to view or sight in total darkness, have been constructed on the basis of this principle. The development of highly sensitive infrared detectors has made it possible to build special devices—thermal direction finders for detecting and finding the direction to objects whose temperature is greater than the background temperature (such as the heated smokestacks of ships, aircraft engines, and the exhaust pipes of tanks) on the basis of their thermal infrared radiation. Guidance systems for projectiles and missiles have also been developed on the basis of the principle of thermal radiation. The special optical system and infrared detector located in the nose cone of a missile receive infrared radiation from a target whose temperature is higher than that of the surrounding medium (for example, the infrared radiation of aircraft, ships, plants, and thermal electric power stations), while the automatic servomechanism connected to the controls guides the missile precisely to the target. Infrared radars and range finders make it possible to detect any objects in the dark and to measure the distance to them.

Optical quantum generators, which radiate in the infrared region, are also used in ground and space communications.

REFERENCES

Lecomte, J. Infrakrasnoe izluchenie. Moscow, 1958. (Translated from French.)
Déribéré, M. Prakticheskie primeneniia infrakrasnykh luchei. Moscow-Leningrad, 1959. (Translated from French.)
Kozelkin, V. V., and I. F. Usol’tsev. Osnovy infrakrasnoi tekhniki. Moscow, 1967.
Solov’ev, S. M. Infrakrasnaia fotografiia. Moscow, 1960.
Lebedev, P. D. Sushka infrakrasnymi luchami. Moscow-Leningrad, 1955.

V. I. MALYSHEV

infrared radiation

[¦in·frə¦red ‚rād·ē′ā·shən] (electromagnetism) Electromagnetic radiation whose wavelengths lie in the range from 0.75 or 0.8 micrometer (the long-wavelength limit of visible red light) to 1000 micrometers (the shortest microwaves).

infrared radiation

radiation

[ra″de-a´shun] 1. a proceeding outward from a common center.2. a structure made up of parts that go outward from a center, especially a tract of the central nervous system made up of fibers that go out in different dfirections.3. energy carried by waves or a stream of particles. One type is radiation" >electromagnetic radiation, which consists of wave motion of electric and magnetic fields. The theory" >quantum theory is based on the fact that electromagnetic waves consist of discrete “packets” of electromagnetic radiation, called photons, which have neither mass nor charge and have an energy inversely proportional to the wavelength of the wave. In order of increasing photon energy and decreasing wavelength, the electromagnetic spectrum is divided into radio waves, infrared light, visible light, ultraviolet light, and x-rays.
Another type is the radiation emitted by radioactive materials. alpha particles are high-energy helium-4 nuclei consisting of two protons and two neutrons, emitted by radioisotopes of heavy elements such as uranium. beta particles are high-energy electrons emitted by radioisotopes of lighter elements. gamma rays are high-energy photons emitted along with alpha and beta particles and also emitted alone by metastable radionuclides, such as technetium-99m. Gamma rays have energies in the x-ray region of the spectrum and differ from x-rays only in that they are produced by radioactive decay rather than by x-ray machines.
Radiation with enough energy to knock electrons out of atoms and produce ions is called radiation" >ionizing radiation and includes alpha particles, beta particles, x-rays, and gamma rays. This kind of radiation can produce tissue damage directly by striking a vital molecule, such as DNA, or indirectly by striking a water molecule and producing highly reactive free radicals that chemically attack vital molecules. The effects of radiation can kill cells, make them unable to reproduce, or cause nonlethal mutations, producing cancer cells or birth defects in offspring. The radiosensitivity of normal tissues or cancer cells increases with their rate of cell division and decreases with their rate of cell specialization. Highly radiosensitive cells include lymphocytes, bone marrow hematopoietic cells, germ cells, and intestinal epithelial cells. Radiosensitive cancers include leukemias and lymphomas, seminoma, dysgerminoma, granulosa cell carcinoma, adenocarcinoma of the gastric epithelium, and squamous cell carcinoma of skin, mouth, nose and throat, cervix, and bladder.
The application of radiation, whether by x-ray or radioactive substances, for treatment of various illnesses is called radiation therapy or radiotherapy.
Three types of units are used to measure ionizing radiation. The roentgen (R) is a unit of exposure dose applicable only to x-rays and gamma rays. It is the amount of radiation that produces 2.58 × 10⁻⁴ coulomb of positive and negative ions passing through 1 kilogram of dry air. The rad is a unit of absorbed dose equal to 100 ergs of energy absorbed per 1 g of absorbing material; the absorbed dose depends both on the type of radiation and on the material in which it is absorbed. The rem is a unit of absorbed dose equivalent that produces the same biologic effect as 1 rad of high-energy x-rays. For beta and gamma radiation, 1 rem is approximately equal to 1 rad; for alpha radiation, 1 rad is approximately 20 rem.
Previously, doses administered in radiation therapy were commonly specified as measured exposure doses in roentgens. The current practice is to specify the absorbed dose in the tissue or organ of interest in rads. Many personnel monitoring devices read out in rems. Eventually, the rad and rem may be replaced by the new SI units, the gray and sievert; 1 gray equals 100 rad, and 1 sievert equals 100 rem.Radiation Hazards. Harmful effects of radiation include serious disturbances of bone marrow and other blood-forming organs, burns, and sterility. There may be permanent damage to genes, which results in genetic mutations. The mutations can be transmitted to future generations. Radiation also may produce harmful effects on the embryo or fetus, bringing about fetal death or malformations. Long-term studies of groups of persons exposed to radiation have shown that radiation acts as a carcinogen; that is, it can produce cancer, especially leukemia. It also may predispose persons to the development of cataracts.
Exposure to large doses of radiation over a short period of time produces a group of symptoms known as the acute radiation syndrome. These symptoms include general malaise, nausea, and vomiting, followed by a period of remission of symptoms. Later, the patient develops more severe symptoms such as fever, hemorrhage, fluid loss, anemia, and central nervous system involvement. The symptoms then gradually subside or become more severe, and may lead to death.Radiation Protection. In order to avoid the radiation hazards mentioned above, one must be aware of the three basic principles of time, distance, and shielding involved in protection from radiation. Obviously, the longer one stays near a source of radiation the greater will be the exposure. The same is true of proximity to the source; the closer one gets to a source of radiation the greater the exposure.
Shielding is of special importance when time and distance cannot be completely utilized as safety factors. In such instances lead, which is an extremely dense material, is used as a protective device. The walls of diagnostic x-ray rooms are lined with lead, and lead containers are used for radium, cobalt-60, and other radioactive materials used in radiotherapy.
Monitoring devices such as the film badge, thermoluminescent dosimeter, or pocket monitor are worn by persons working near sources of radiation. These devices contain special detectors that are sensitive to radiation and thus serve as guides to the amount of radiation to which a person has been exposed. For monitoring large areas in which radiation hazards may pose a problem, survey meters such as the Geiger counter may be used. The survey meter also is useful in finding sources of radiation such as a radium implant, which might be lost.
Sensible use of these protective and monitoring devices can greatly reduce unnecessary exposure to radiation and allow for full realization of the many benefits of radiation.

Penetrating capacity of different types of radiation. From Ignatavicius and Workman, 2002.

Radiation is emitted by radioactive material. Radiation quantity is measured in roentgens, rads, or rems, depending on precise use. From Bushong, 2001.corpuscular radiation particles emitted in nuclear disintegration, including alpha and beta particles, protons, neutrons, positrons, and deuterons.electromagnetic radiation energy, unassociated with matter, that is transmitted through space by means of waves (electromagnetic waves) traveling in all instances at 3×10¹⁰ cm or 186,284 miles per second, but ranging in length from 10¹¹ cm (electrical waves) to 10⁻¹² cm (cosmic rays) and including radio waves, infrared, visible light and ultraviolet, x-rays, and gamma rays.extrafocal radiation radiation that arises from a source other than the focal spot of the x-ray tube.infrared radiation the portion of the spectrum of electromagnetic radiation of wavelengths between 0.75 and 1000 μm; see also infrared.interstitial radiation energy emitted by radium, radon, or some other radiopharmaceutical inserted directly into the tissue; see also radiation therapy.ionizing radiation corpuscular or electromagnetic radiation that is capable of producing ions, directly or indirectly, in its passage through matter. See also radiation.optic radiation either of two large fan-shaped fiber tracts in the brain extending from the lateral geniculate body on either side to the striate cortexprimary radiation that coming directly from a source, such as a radioactive substance or an x-ray tube, without interactions with matter.pyramidal radiation fibers extending from the pyramidal tract to the cortex.scatter radiation (secondary radiation) that generated by the interaction of radiation" >primary radiation with matter. See illustration.

Three types of radiation—the useful beam, leakage radiation, and scatter radiation. From Bushong, 2001.striothalamic radiation a fiber system joining the thalamus and the hypothalamic region.tegmental radiation fibers radiating laterally from the nucleus ruber.thalamic r's fibers streaming out through the lateral surface of the thalamus, through the internal capsule to the cerebral cortex.ultraviolet radiation the portion of the spectrum of electromagnetic radiation of wavelengths between 0.39 and 0.18 μm; see also ultraviolet rays.

radiation

(rad-e-a'shon) [L. radiatio, a shining] 1. The process by which energy is propagated through space or matter.2. The emission of rays in all directions from a common center.3. Ionizing rays used for diagnostic or therapeutic purposes. Two types of radiation therapy are commonly used for patients with cancer: teletherapy and brachytherapy. See: brachytherapy4. Any form of radiant energy emission or divergence, as of energy in all directions from luminous bodies, radiographical tubes, particle accelerators, radioactive elements, and fluorescent substances.5. In neurology, a group of fibers that diverge from a common origin.

acoustic radiation

Auditory radiation.

actinic radiation

Ionizing electromagnetic radiation that can produce chemical changes, e.g., the damage done to skin by ultraviolet sunlight.

auditory radiation

A band of fibers that connect auditory areas of the cerebral cortex with the medial geniculate body of the thalamus. Synonym: acoustic radiation

background radiation

Total radioactivity from cosmic rays, natural radioactive materials, and other radiation that is present in a specific area.

braking radiation

Synonym: bremsstrahlung radiation

bremsstrahlung radiation

Diagnostic radiation produced at the target of the anode in an x-ray tube. An electron is accelerated at high speed from the x-ray tube cathode filament. It interacts with the nuclear field of a target atom, changing direction and losing energy that is emitted in the form of an ionizing radiation photon. The result is a heterogeneous beam. Synonym: braking radiation

characteristic radiation

In radiology, the production of radiation in an anode caused by an interaction between an electron from the electron stream and an inner-shell electron of the target material. The result is an ejected electron, a positive atom, and an x-ray photon characteristic of the difference in binding energies between the atomic shells.

radiation of corpus callosum

All the fibers emanating from the corpus callosum into each cerebral hemisphere.

corpuscular radiation

Radiation composed of discrete elements or particles such as elements of atomic nuclei, i.e., alpha, beta, neutron, positron, or proton particles.

cosmic radiation

Ionizing radiation from the sun and other extraterrestrial sources. It has a short wavelength, high velocity, and an exceptional ability to penetrate tissue. It accounts for about one tenth of the yearly total of ionizing radiation exposure for each person. Colloquially, it is known as “cosmic rays.”

electromagnetic radiation

Photons that travel at the speed of light. They exhibit both magnetic and electrical properties. See: electromagnetic spectrum for table

heterogeneous radiation

Radiation containing waves of various wavelengths.

homogeneous radiation

Radiation containing photons of similar wavelength.

infrared radiation

Infrared ray.

interstitial radiation

Radiation treatment accomplished by inserting sealed sources of a particle emitter directly into tissues.

ionizing radiation

Electromagnetic waves capable of producing ions after interaction with matter. Examples include x-rays, gamma rays, and beta particles. See: ionizing radiation injury

irritative radiation

An overdose of ultraviolet irradiation resulting in erythema and, in exceptional cases, blister formation.

low-level radiation

Electromagnetic waves at intensity levels below that known to cause obvious damage to living things. Low-level radiation includes that emitted by power lines, nuclear power plants, and appliances such as electric blankets, television sets, and computer terminals.

nonionizing radiation

Abbreviation: NIR
Electromagnetic radiation that does not readily ionize atoms such as that in visible light, ultraviolet light, infrared light, microwaves, ultrasound, and radiofrequency emissions.

optic radiation

A system of fibers extending from the lateral geniculate body of the thalamus through the sublenticular portion of the internal capsule to the calcarine occipital cortex (striate area). Synonym: geniculocalcarine tract

photochemical radiation

Light rays that penetrate tissues only fractions of a millimeter, are absorbed by cells, and cause physical and biological changes. This type of radiation causes surface heating.

photothermal radiation

Radiation of heat by a source of light, as that from an electric bulb.

primary radiation

That radiation being emitted directly to the patient from an x-ray source.

pyramidal radiation

The radiation of fibers from the cerebral cortex to the pyramidal tract.

remnant radiation

Ionizing radiation that passes through the part being examined to make the radiographical image.

scattered radiation

X-rays that have changed direction because of a collision with matter.

secondary radiation

X-rays produced by the interaction between primary radiation and the substance being radiated.

solar radiation

Radiation from the sun; 60% is infrared and 40% is visible and ultraviolet.

spatially fractionated radiation

Abbreviation: SFR
Radiation treatment applied in high doses to a large tumor through a grid designed to direct energy into multiple discrete regions of the mass.

striatomesencephalic radiation

Fibers originating in the corpus striatum and terminating principally in the substantia nigra of the midbrain.

striatosubthalamic radiation

A system of fibers consisting of three groups that emerge from the medial aspect of the lentiform nucleus and enter the subthalamic region, most terminating there but some continuing into the midbrain. Synonym: ansa lenticularis

striatothalamic radiation

Groups of fibers connecting the corpus striatum with the thalamus and subthalamus.

synchrotron radiation

Radiation released by charged particles accelerated by a synchrotron. It may be used to obtain noninvasive images of body structures (e.g., the coronary arteries) or to study the structure of proteins, tissue samples, or other objects of biological or medical interest.

thalamic radiation

Groups of fibers connecting the thalamus with the cerebral hemispheres. These include frontal, centroparietal, occipital, and optic radiations.

thermal radiation

Heat radiation.

ultraviolet radiation

Radiant energy extending from 3900 to 200 angstrom units (A.U.) Divided into near ultraviolet, which extends from 3900 to 2900 A.U., and far ultraviolet, which extends from 2900 to 200 A.U.

visible radiation

The radiation of the visible spectrum, which may be broken up into different wavelengths representing different colors:

Violet, 3900–4550 angstrom units (A.U.)

Blue, 4550–4920 A.U.

Green, 4920–5770 A.U.

Yellow, 5770–5970 A.U.

Orange, 5970–6220 A.U.

Red, 6220–7700 A.U.

x radiation

1. A form of electromagnetic radiation with wavelengths in the range of 0.01 to 10 nm, frequencies from 3 × 10¹⁶ Hz to 3 × 10¹⁹ Hz, and energies in the range 120 eV to 120 keV. 2. Treatment with or exposure to x-rays.

infrared radiation

infrared radiation

infrared radiation

infrared radiation

infrared radiation,

Infrared radiation

infrared radiation

Infrared Radiation

REFERENCES

infrared radiation

infrared radiation

radiation

radiation

acoustic radiation

actinic radiation

auditory radiation

background radiation

braking radiation

bremsstrahlung radiation

characteristic radiation

radiation of corpus callosum

corpuscular radiation

cosmic radiation

electromagnetic radiation

heterogeneous radiation

homogeneous radiation

infrared radiation

interstitial radiation

ionizing radiation

irritative radiation

low-level radiation

nonionizing radiation

optic radiation

photochemical radiation

photothermal radiation

primary radiation

pyramidal radiation

remnant radiation

scattered radiation

secondary radiation

solar radiation

spatially fractionated radiation

striatomesencephalic radiation

striatosubthalamic radiation

striatothalamic radiation

synchrotron radiation

thalamic radiation

thermal radiation

ultraviolet radiation

visible radiation

x radiation

infrared radiation

Synonyms for infrared radiation

noun electromagnetic radiation with wavelengths longer than visible light but shorter than radio waves

Synonyms

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