| 释义 |
radiation
ra·di·a·tion R0011700 (rā′dē-ā′shən)n.1. The act or process of radiating: the radiation of heat and light from a fire.2. Physics a. Emission or propagation of energy in the form of waves or particles.b. Energy radiated or transmitted in the form of waves or particles.c. A stream of particles or electromagnetic waves emitted by the atoms and molecules of a radioactive substance as a result of nuclear decay.3. a. The act of exposing or the condition of being exposed to such energy.b. The application of such energy, as in medical treatment.4. Anatomy Radial arrangement of parts, as of a group of nerve fibers connecting different areas of the brain.5. Adaptive radiation
ra′di·a′tion·al, ra′di·a′tive adj.radiation (ˌreɪdɪˈeɪʃən) n1. (General Physics) physics a. the emission or transfer of radiant energy as particles, electromagnetic waves, sound, etcb. the particles, etc, emitted, esp the particles and gamma rays emitted in nuclear decay2. (Medicine) med Also called: radiation therapy treatment using a radioactive substance3. (Anatomy) anatomy a group of nerve fibres that diverge from their common source4. (Biology) See adaptive radiation5. the act, state, or process of radiating or being radiated6. (Surveying) surveying the fixing of points around a central plane table by using an alidade and measuring tape ˌradiˈational adjra•di•a•tion (ˌreɪ diˈeɪ ʃən)
n. 1. a. the process in which energy is emitted as particles or waves. b. the complete process in which energy is emitted by one body, transmitted through an intervening medium or space, and absorbed by another body. c. the energy transferred by these processes. 2. the act or process of radiating. 3. something that is radiated. 4. radial arrangement of parts. [1545–55; < Latin radiātiō gleam. See radiate, -tion] ra`di•a′tion•al, adj. ![]() radiationAs the nucleus of a radioactive element decays, it releases alpha particles, beta particles, or gamma rays. Alpha rays (a stream of alpha particles) are the weakest form of radiation and can be stopped by paper. Beta rays (a stream of beta particles) are able to pass through paper but not through aluminum. Gamma rays (a form of electromagnetic radiation) are the strongest. They are able to pass through paper and aluminum, but not through a block of lead or concrete.ra·di·a·tion (rā′dē-ā′shən)1. a. Energy in the form of electromagnetic waves or streams of particles, such as photons or electrons. Radiation is given off by nuclear reactions (as in fission) and by radioactive decay.b. The emission or movement of such energy through space or a medium, such as air. See Notes at conduction, electromagnetic radiation.2. The use of such energy, especially x-rays, in medical diagnosis and treatment.RadiationSee also physics.
actinotherapyradiotherapy.bolographthe record produced by a bolometer.bolometera device used in bolometry.bolometrythe measurement of minute amounts of radiant energy, especially infrared spectra. — bolometrist, n. — bolometric, adj.curiescopyradioscopy.diathermancythe capacity to transmit infrared radiation. — diathermanous, adj.dosimetera device, carried or worn by people working near radiation for measuring the amount of radiation to which they are exposed.dosimetrythe measurement by a dosimeter of the dosage of radiation a person might have received. See also drugs. — dosimetrist, n. — dosimetric, dosimetrical adj.fluorometeran instrument for measuring the emission of radiation in the form of visible light and identifying the substance that is its source. — fluorometric, adj.fluorometrythe measurement of fluorescence, or visible radiation, by means of a fluorometer. — fluorometric, adj.fluoroscopyan examination by means of a screen coated with a fluorescent substance responsive to radiation from x rays. — fluoroscopic, adj.metallographythe study of metals and their structures and properties by the use of microscopy and x rays.pyelographythe science or technique of making x-ray photographs of the kidneys, renal pelves, and ureters, using injection of opaque solutions or radiopaque dyes. — pyelographic, adj.radiesthesiathe sensitivity of some humans to radiation of various kinds, as in water divining or nonmedical diagnosis. — radiesthetic, adj.radioactivitythe state, property, or process of being radioactive.radiographythe production of photographic images on film using radiation from other radioactive substances instead of light. Also called x-ray scotography, shadowgraphy. — radiograph, radiographer, n. — radiographic, radiographical, adj.radiology1. the science that studies x rays or radiation from radioactive substances, esp. for medical purposes.
2. the examination or photographing of parts of the body with such rays.
3. the interpretation of the resulting photographs. — radiologist, n. — radiologie, radiological, adj.radiometallographythe study of metals and their structures by the use of x rays.radioscopythe study or observation of the inner structure of opaque materials by means of x rays or other radioactive substances. Also called curiescopy.radiosensibilitysensitivity to the effects of radiation, as of parts of the body. Also called radiosensitivity.radiosensitivityradiosensibility. — radiosensitive, adj.radiotechnologythe science and technology of applying radiation and x rays to industrial use. See also radio.radiotherapya method of treating diseases with x rays or the radiation from other radioactive substances. Also called actinotherapy. — radiotherapist, n. — radiotherapeutic, adj.roentgenism, röntgenism1. the treatment of disease with x rays or roentgen rays.
2. the effect of misuse or overexposure to these rays.roentgenogram, röntgenograman x-ray photograph.roentgenography, röntgenographyx-ray photography.scotographa radiograph.shadowgraphyradiography.tomographyx-ray photography of a selected plane of the body by a method that eliminates the outline of structures in other planes. — tomographic, adj.xeroradiographya process of recording x-ray images by electrostatic means. — xeroradiographic, adj.x-ray scotographyradiography.radiationElectromagnetic and radioactive energy emitted as rays, waves, or particles.Thesaurus| Noun | 1. |  radiation - energy that is radiated or transmitted in the form of rays or waves or particlesionizing radiation - high-energy radiation capable of producing ionization in substances through which it passescosmic radiation - radiation coming from outside the solar systemelectromagnetic radiation, electromagnetic wave, nonparticulate radiation - radiation consisting of waves of energy associated with electric and magnetic fields resulting from the acceleration of an electric chargeenergy, free energy - (physics) a thermodynamic quantity equivalent to the capacity of a physical system to do work; the units of energy are joules or ergs; "energy can take a wide variety of forms"solar radiation - radiation from the sun | | 2. | radiation - the act of spreading outward from a central sourcebombardment - the act (or an instance) of subjecting a body or substance to the impact of high-energy particles (as electrons or alpha rays)emission, emanation - the act of emitting; causing to flow forth | | 3. | radiation - syndrome resulting from exposure to ionizing radiation (e.g., exposure to radioactive chemicals or to nuclear explosions); low doses cause diarrhea and nausea and vomiting and sometimes loss of hair; greater exposure can cause sterility and cataracts and some forms of cancer and other diseases; severe exposure can cause death within hours; "he was suffering from radiation"radiation sickness, radiation syndromesyndrome - a pattern of symptoms indicative of some disease | | 4. | radiation - the spontaneous emission of a stream of particles or electromagnetic rays in nuclear decayradioactivitycorpuscular radiation, particulate radiation - a stream of atomic or subatomic particles that may be charged positively (e.g. alpha particles) or negatively (e.g. beta particles) or not at all (e.g. neutrons)emission - the release of electrons from parent atoms | | 5. | radiation - the spread of a group of organisms into new habitatsadaptive radiation - the development of many different forms from an originally homogeneous group of organisms as they fill different ecological nichesspread, spreading - process or result of distributing or extending over a wide expanse of spacenatural action, natural process, action, activity - a process existing in or produced by nature (rather than by the intent of human beings); "the action of natural forces"; "volcanic activity" | | 6. | radiation - a radial arrangement of nerve fibers connecting different parts of the brainneural structure - a structure that is part of the nervous system | | 7. |  radiation - (medicine) the treatment of disease (especially cancer) by exposure to a radioactive substanceactinotherapy, radiation therapy, radiotherapy, irradiationtherapy - (medicine) the act of caring for someone (as by medication or remedial training etc.); "the quarterback is undergoing treatment for a knee injury"; "he tried every treatment the doctors suggested"; "heat therapy gave the best relief"phototherapy - the use of strong light to treat acne or hyperbilirubinemia of the newbornCurietherapy, radium therapy - the use of radium in radiation therapyX-ray therapy - the therapeutic use of X raysmedical specialty, medicine - the branches of medical science that deal with nonsurgical techniques |
radiationnoun emission, rays, emanation They study energy radiation from the most violent stars in the universe.Translationsradiate (ˈreidieit) verb1. to send out rays of (light, heat etc). A fire radiates heat. 射出(光或熱) 辐射（热或光） 2. to go out or be sent out in rays, or in many directions from a central point. Heat radiates from a fire; All the roads radiate from the centre of the town. 四散 发散ˌradiˈation noun rays of light, heat etc or of any radioactive substance. 輻射 辐射ˈradiator noun1. a type of apparatus for heating a room. 暖氣裝置 暖气装置, ，散热器, ，暖气片 2. an apparatus in a car which, with a fan, cools the engine. 汽車引擎散熱器 （汽车引擎的）冷却器
radiation
radiation (rā'dēā`shən), term applied to the emission and transmission of energy through space or through a material medium and also to the radiated energy itself. In its widest sense the term includes electromagnetic, acoustic, and particle radiation, and all forms of ionizing radiation. Commonly radiation refers to 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. , which, in order of decreasing wavelength, includes radio, microwave, infrared, visible-light, ultraviolet, X-ray, and gamma-ray emissions. All of these travel through space at the speed of light (c.300,000 km/186,000 mi per sec) but differ in wavelength and frequency. According to the quantum theoryquantum theory,
modern physical theory concerned with the emission and absorption of energy by matter and with the motion of material particles; the quantum theory and the theory of relativity together form the theoretical basis of modern physics.
..... Click the link for more information. , the energy carried in the form of 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. may be viewed as made up of tiny bundles or packets, each bundle being known as a photonphoton
, the particle composing light and other forms of electromagnetic radiation, sometimes called light quantum. The photon has no charge and no mass. About the beginning of the 20th cent.
..... Click the link for more information. . The sun is the source of much radiant energy in the form of sunlight and heat. Heat radiation is infrared radiationinfrared radiation,
electromagnetic radiation having a wavelength in the range from c.75 × 10−6 cm to c.100,000 × 10−6 cm (0.000075–0.1 cm).
..... Click the link for more information. . All types of electromagnetic radiation can be reflected and absorbed in the same manner as is visible light. Acoustic radiation, propagated as sound waves, may be sonic (in the frequency range from 16 to 20,000 cycles per sec), infrasonic, or subsonic (frequency less than 16 cycles per sec), and ultrasonic (frequency greater than 20,000 cycles per sec). Examples of particle radiation are alpha and beta rays in radioactivityradioactivity,
spontaneous disintegration or decay of the nucleus of an atom by emission of particles, usually accompanied by electromagnetic radiation. The energy produced by radioactivity has important military and industrial applications.
..... Click the link for more information. , and many kinds of atomic and subatomic particles such as electrons, mesons, neutrons, protons, and heavier nuclei (see cosmic rayscosmic rays,
charged particles moving at nearly the speed of light reaching the earth from outer space. Primary cosmic rays consist mostly of protons (nuclei of hydrogen atoms), some alpha particles (helium nuclei), and lesser amounts of nuclei of carbon, nitrogen, oxygen, and
..... Click the link for more information. ). Radiation is usually considered to travel from a source in straight lines, but its path may be affected by external factors; for instance, charged particles travel in curved paths in magnetic fields. The Van Allen radiation beltsVan Allen radiation belts,
belts of radiation outside the earth's atmosphere, extending from c.400 to c.40,000 mi (c.650–c.65,000 km) above the earth. The existence of two belts, sometimes considered as a single belt of varying intensity, was confirmed from information
..... Click the link for more information. consist of charged particles trapped in the earth's magnetic field.Radiation The emission and propagation of energy; also, the emitted energy itself. The etymology of the word implies that the energy propagates rectilinearly, and in a limited sense, this holds for the many different types of radiation encountered. The major types of radiation may be described as electromagnetic, acoustic, and particle, and within these major divisions there are many subdivisions. Electromagnetic radiation is classified roughly in order of decreasing wavelength as radio, microwave, visible, ultraviolet, x-rays, and γ-rays. Acoustic or sound radiation may be classified by frequency as infrasonic, sonic, or ultrasonic in order of increasing frequency, with sonic being between about 16 and 20,000 Hz. The traditional examples of particle radiation are the α‒ and β-rays of radioactivity. See Electromagnetic radiation, Radioactivity, Sound radiation (ray-dee-ay -shŏn) See electromagnetic radiation; energy transport.radiation[‚rād·ē′ā·shən] (engineering) A method of surveying in which points are located by knowledge of their distances and directions from a central point. (physics) The emission and propagation of waves transmitting energy through space or through some medium; for example, the emission and propagation of electromagnetic, sound, or elastic waves. The energy transmitted by waves through space or some medium; when unqualified, usually refers to electromagnetic radiation. Also known as radiant energy. A stream of particles, such as electrons, neutrons, protons, α-particles, or high-energy photons, or a mixture of these. radiationThe transmission of heat through space by means of electromagnetic waves; the heat energy passes through the air between the source and the heated body without heating the intervening air appreciably.radiationi. The process of heat transfer in wave form without the use or necessity of a transmitting medium. The insolation, or radiant energy, received by the earth from the sun is an example of radiation.
ii. The transfer of energy in the form of electromagnetic waves through either a vacuum or air.radiation1. Physicsa. the emission or transfer of radiant energy as particles, electromagnetic waves, sound, etc. b. the particles, etc., emitted, esp the particles and gamma rays emitted in nuclear decay 2. Med treatment using a radioactive substance 3. Anatomy a group of nerve fibres that diverge from their common source 4. See adaptive radiationradiation
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.ra·di·a·tionradiophobia.
ra·di·a·tion (rā'dē-ā'shŭn), 1. The act or condition of diverging in all directions from a center. 2. The sending forth of light, short radio waves, ultraviolet rays or x-rays, or any other rays for treatment, diagnosis, or another purpose. Compare: irradiation (2). 3. Synonym(s): radiatio4. A ray. 5. Radiant energy or a radiant beam. [L. radiatio, fr. radius, ray, beam] radiation (rā′dē-ā′shən)n.1. The act or process of radiating: the radiation of heat and light from a fire.2. Physics a. Emission or propagation of energy in the form of waves or particles.b. Energy radiated or transmitted in the form of waves or particles.c. A stream of particles or electromagnetic waves emitted by the atoms and molecules of a radioactive substance as a result of nuclear decay.3. a. The act of exposing or the condition of being exposed to such energy.b. The application of such energy, as in medical treatment.4. Anatomy Radial arrangement of parts, as of a group of nerve fibers connecting different areas of the brain.5. Adaptive radiation
ra′di·a′tion·al, ra′di·a′tive adj.The combined processes of emission, transmission and absorption of highly energetic waves and particles on the electromagnetic spectrum; well-known effects of radiation include changes in cells, especially those with rapid turnover—e.g., colon, haematopoietic tissues
Medspeak The direct, band-like extension of a sensation, in particular of pain, from a point of origin to another region of the body
Oncology The administration of ionizing radiation to kill malignant tumour cells
Physics An emission of energy in the form of photons—gamma, x-rays; particles—alpha, beta, positrons, neutrons or waves—heat, light, radio waves and microwavesradiation The combined processes of emission, transmission and absorption of highly energetic waves and particles on the electromagnetic spectrum treatment to kill cancer cells. See Acute radiation injury, Alpha radiation, Background radiation, Chemoradiation, Coherent radiation, Corpuscular radiation, Definitive radiation, Electromagnetic radiation, External radiation, Gamma radiation, Grenz radiation, Implant radiation, Internal radiation, Ionizing radiation, Non-ionizing radiation, Remnant radiation, Scattered radiation, Synchrotron radiation, Total body irradiation Clinical practice The direct, band-like extension of a sensation, in particular of pain, from a point of origin to another region of the body. Cf Referred pain Oncology The administration of ionizing radiation to kill malignant tumor cells. See Radiation fibrosis, Radiation therapy. Radiation
Alpha radiation 2 protons and 2 neutrons, eg plutonium, radon; α radiation travels 15 cm in air and is stopped by a piece of paper; proven role in soft tissue malignancy–see Radium Dial company, relationship with epithelial malignancy is uncertain; it is present in cigarette smoke and may have an additive effect to the known carcinogenic effect of tar; emitted by radium, thorium, uranium. Beta radiation Electrons, eg strontium-90, tritium–3H; β radiation travels at the speed of light, is stopped by wood and thin metals and is carcinogenic to skin Gamma radiation Gamma photon A quantum of electromagnetic radiation of ≤ 1 nm, which is generated by unstable nuclei eg 60Co; γ radiation is stopped by several feet of heavy concrete or 10-40 cm of lead and is linked to cancer, inducing mutations at the glycophorin A locus in survivors of atomic blasts; 183/105 excess deaths in survivors of the Hiroshima and Nagasaki blasts, with a 13-fold ↑ in non-lymphocytic leukemia–peaking at 6 yrs post-blast, thyroid nodules and tumors–peaking at 15-20 years post-blast and multiple myeloma 6-fold ↑–peaking 30 yrs post-blast ra·di·a·tion (rā'dē-ā'shŭn) 1. The act or condition of diverging in all directions from a center. 2. The sending forth of light, short radio waves, ultraviolet or x-rays, or any other rays for treatment or diagnosis or for other purpose.
Compare: irradiation (2) 3. Synonym(s): radiatio. 4. A ray. 5. Radiant energy or a radiant beam. [L. radiatio, fr. radius, ray, beam]radiation The emission and almost instantaneous propagation of electromagnetic waves ranging in wavelength from thousands of metres (radio waves) to millionths of millionths of millimetres (gamma rays). Radiation of long wavelength may cause body atoms and molecules to vibrate but does not, so far as is known, significantly damage them (non-ionizing radiation). Very short wavelength radiation, such as X-rays and gamma rays (ionizing radiation), however, can knock out linking electrons from molecules, causing them to separate into smaller charged bodies or chemical groups called ions, or FREE RADICALS. Ionizing radiation can damage any body molecules, including DNA, and this may kill cells or alter their genetic structure. Such mutations in surviving cells may lead to cancer. At the same time, rapidly dividing cancer cells are more susceptible to the effects of ionizing radiation than normal cells. This is the basis of RADIOTHERAPY.radiation the electromagnetic energy that travels through empty space with the speed of light (2×108 ms -1). All objects emit radiation, at room temperature mostly in the infrared range, whereas at high temperatures visible radiation is produced. See ELECTROMAGNETIC SPECTRUM, ULTRAVIOLET LIGHT, X-RAY.radiation 1. Emission or transfer of energy in the form of electromagnetic waves or particles. 2. A group of nerve fibres that diverge in all directions from a point of origin. Example: the optic radiations. See electromagnetic spectrum.ra·di·a·tion (rā'dē-ā'shŭn) 1. Sending forth light, short radio waves, ultraviolet rays or x-rays, or any other rays for treatment, diagnosis, or another purpose. 2. Act or condition of diverging in all directions from a center. [L. radiatio, fr. radius, ray, beam]Patient discussion about radiationQ. Is an X- Ray dangerous to my fetus? I fell down while I am pregnant and was sent to the ER. I was given an x- ray there, is the radiation dangerous to my fetus?A. As far as I know one x-ray cannot harm your fetus since there is not enough radiation there to harm it. If you are worried consult a Doctor. Q. What does radiation do for cancer patients? We found out today that my grandmother has cancer and my mother said that the oncologist is planning on using radiation to ease her pain. My question is, what does radiation do? I know, eases pain, but how?A. hello;radiation therapy/an anticancer drugs are used to suppress or arrest the rate of cell division in any tumor cells, the rad also kills good cells also. Q. Is it proven that cellular radiation can damage health? A. it was proven that people that talk a lot with cellular phones tend to develop problems in their salivary gland (the Parotid gland, right under the ear)that is on the side they speak the most.
http://www.newsinferno.com/archives/2163
could be that in 15 years from now the amount of brain cancer will increase and they will know for sure it's from cellular phones. , why take a chance- use as less as possible, use an earphone and don't give a cellular phone to your children until they are 17.
you can never know what will they find next... More discussions about radiationSee RADN
See RADNradiation
Related to radiation: electromagnetic radiation, Radiation poisoningSynonyms for radiationnoun emissionSynonymsSynonyms for radiationnoun energy that is radiated or transmitted in the form of rays or waves or particlesRelated Words- ionizing radiation
- cosmic radiation
- electromagnetic radiation
- electromagnetic wave
- nonparticulate radiation
- energy
- free energy
- solar radiation
noun the act of spreading outward from a central sourceRelated Words- bombardment
- emission
- emanation
noun syndrome resulting from exposure to ionizing radiation (e.g., exposure to radioactive chemicals or to nuclear explosions)Synonyms- radiation sickness
- radiation syndrome
Related Wordsnoun the spontaneous emission of a stream of particles or electromagnetic rays in nuclear decaySynonymsRelated Words- corpuscular radiation
- particulate radiation
- emission
noun the spread of a group of organisms into new habitatsRelated Words- adaptive radiation
- spread
- spreading
- natural action
- natural process
- action
- activity
noun a radial arrangement of nerve fibers connecting different parts of the brainRelated Wordsnoun (medicine) the treatment of disease (especially cancer) by exposure to a radioactive substanceSynonyms- actinotherapy
- radiation therapy
- radiotherapy
- irradiation
Related Words- therapy
- phototherapy
- Curietherapy
- radium therapy
- X-ray therapy
- medical specialty
- medicine
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