radiation (redirected from speed of radiation)

radiation /ra·di·a·tion/ (ra″de-a´shun)

1. divergence from a common center.

2. a structure made up of divergent elements, as one of the fiber tracts in the brain.

3. energy transmitted by waves through space or through some medium; usually referring to electromagnetic radiation, when used without a modifier. By extension, a stream of particles, such as electrons or alpha particles.

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acoustic radiation  a fiber tract arising in the medial geniculate nucleus and passing laterally to terminate in the transverse temporal gyri of the temporal lobe.

radiation of corpus callosum  the fibers of the corpus callosum radiating to all parts of the neopallium.

corpuscular radiations  streams of subatomic particles emitted in nuclear disintegration, such as protons, neutrons, positrons, and deuterons.

electromagnetic radiation  see under wave.

ionizing radiation  corpuscular or electromagnetic radiation capable of producing ionization, directly or indirectly, in its passage through matter.

occipitothalamic radiation , optic radiation a fiber tract starting at the lateral geniculate body, passing through the pars retrolentiformis of the internal capsule, and terminating in the striate area on the medial surface of the occipital lobe, on either side of the calcarine sulcus.

pyramidal radiation  fibers extending from the pyramidal tract to the cortex.

tegmental radiation  fibers radiating laterally from the red nucleus.

thalamic radiations  fibers which reciprocally connect the thalamus and cerebral cortex by way of the internal capsule, usually grouped into four subradiations (peduncles): anterior, central, inferior, and posterior.

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ra·di·a·tion (rd-shn)

n.

1. The act or condition of diverging in all directions from a center.

2. The emission and propagation of energy in the form of rays or waves.

3. The energy radiated or transmitted in the form of rays, waves, or particles.

4. A stream of particles or electromagnetic waves that is emitted by the atoms and molecules of a radioactive substance as a result of nuclear decay.

5. Radiotherapy.

6. The radial arrangement of anatomical or histological parts.

7. The spread of a group of organisms into new habitats.

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radiation

[rā′dē·ā′shən]

Etymology: L, radiatio

1 the emission of energy, rays, or waves.

2 the use of a radioactive substance in the diagnosis or treatment of disease.

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radiation (rā´dēā´shn),

n 1. the process of emitting radiant energy in the form of waves or particles.
n 2. the combined processes of emission, transmission, and absorption of radiant energy.

radiation, actinic,

n radiation capable of producing chemical change (e.g., effect of light and roentgen rays on photographic emulsions).

radiation, background,

n radiation arising from radioactive material other than the one directly under consideration. Background radiation resulting from cosmic rays and natural radioactivity is always present. Background radiation may also exist because of radioactive substances in other parts of a building (e.g., building material).

Radiation.

radiation, backscatter,

n radiation that deflects off its target at an angle of deflection greater than 90°, possibly affecting those who may be off to the side of or behind the main beam. See also radiation, scattered.

radiation, biologic effectiveness of,

n the ability of a particular type of ionizing radiation to produce biologic effects on an organism with small absorbed doses. See relative biologic effectiveness.

radiation, bremsstrahlung

n (white), describes the distribution of roentgen rays from extremely low energy photons to roentgen rays originating from the highest kilovoltage applied to a radiographic tube.
Bremsstrahlung translates to “braking radiation,” referring to the sudden slowing of electrons that occurs when they encounter nuclei with a high positive charge.

radiation caries,

n a type of tooth decay caused by the reduction in saliva that may result from the use of ionizing radiation in the treatment of oral and facial malignancies. Radiation caries is an unfortunate side effect of a necessary radical procedure to cure or prevent the spread of cancer.

radiation cataract,

n a cataract that is caused by extended exposure of the eye to ionizing radiation in the course of treating facial cancers.

radiation, characteristic,

n radiation that originates from an atom after removal of an electron or excitation of the nucleus. The wavelength of the emitted radiation is specific, depending only on the element concerned and on the particular energy levels involved. Also refers to the specific type of secondary radiation resulting when rays from a radio ray tube strike another substance, such as copper.

radiation, coherent scattering,

n See coherent scattering.

radiation, Compton scatter,

n See Compton scatter radiation.

radiation, corpuscular

n subatomic particles, such as electrons, protons, neutrons, or alpha particles, that travel in streams at various velocities. All the particles have definite masses and travel at various speeds. The properties are in opposition to electromagnetic radiations, which have no mass and travel in wave forms at the speed of light. See also radiation, electromagnetic.

radiation, cosmic,

n See ray, cosmic.

radiation, cumulative effect of

n reactions vary depending on the dosage; if the radiation received is in several smaller doses, the reaction is not as severe as if the same amount of radiation is received all at once. Unless a tissue is completely destroyed by the radiation, some or all of it will be repaired, although cumulative damage may cause some irreparable conditions.

radiation, dermatitis,

n See dermatitis, radiation.

radiation detector,

n a device for converting radiant energy to a form more suitable for observation and recording. Examples include radiograph films and radiometers.

radiation, direct,

n (primary radiation), radiation emanating from a tube aperture and comprising the useful beam, as compared with any stray radiation, such as that which comes from the tube container.

radiation, electromagnetic,

n forms of energy propagated by wave motion, such as photons or discrete quanta. The radiations have no matter associated with them, as opposed to corpuscular radiations, which have definite masses. They differ widely in wavelength, frequency, and photon energy and have strikingly different properties. Covering an enormous range of wavelengths (from 10⁻⁶ to 10¹⁷ Å), they include radio waves, infrared waves, visible light, ultraviolet radiation, gamma rays, and cosmic radiation. See also radiation, corpuscular.

radiation exposure,

n a measure of the ionization produced in air by roentgen rays or gamma rays. It is the sum of the electric charges on all ions of one sign that are produced when all electrons liberated by photons in a volume of air are completely stopped, divided by the mass of air in the volume element. The unit of exposure is the roentgen.

radiation field,

n See radiographic beam, field size.

radiation, gamma,

n See ray, gamma.

radiation, genetic effects of,

n See genetic effects of radiation.

radiation, grenz,

n See ray, grenz.

radiation, hard,

radiation consisting of the short wavelengths (higher kilovolt peak equals greater penetration).

radiation hazard,

n See hazard, radiation.

radiation, heterogeneous

n a beam or “bundle” of radiation containing photons of many wavelengths.

radiation, homogeneous,

n a beam of radiation consisting of photons that all have the same wavelength.

radiation hygiene,

n See hygiene, radiation.

radiation intensity,

n See intensity, radiation.

radiation, ionizing,

n electomagnetic radiation such as roentgen rays and gamma rays; particulate radiation such as alpha particles, beta particles, protons, and neutrons; all other types of radiations that produce ionization directly or indirectly.

radiation leakage,

n (stray radiation), the escape of radiation through the protective shielding of the radiography unit tube head. This radiation is detected at the sides, top, bottom, or back of the tube head; it does not include the useful beam.

radiation, monochromatic,

n See radiation, homogeneous.

radiation necrosis,

n See necrosis, radiation.

radiation, neutron,

n See ray, neutron.

radiation oncology,

n the study of the treatment of cancer using ionizing radiation

radiation osteomyelitis/osteonecrosis

n an infection of the bone that occurs after exposure to radiation. Most commonly seen in cancer patients when radiation therapy damages healthy tissue surrounding the targeted tumor.

radiation, primary,

n all radiation produced directly from the target in a radiographic tube. See also radiation, direct.

radiation protection,

n provision designed to reduce exposure to radiation. For external radiation, this provision consists of using protective barriers of radiation-absorbing material, ensuring adequate distances from the radiation sources, reducing exposure time, and combinations of these measures. For internal radiation, it involves measures to restrict inhalation, ingestion, or other modes of entry of radioactive material into the body.

radiation quality,

n the ability of a beam of radiographs to allow the production of diagnostically useful radiographs. Usually measured in half-value layers of aluminum and controlled by the kilovolt peak.

radiation quantity,

n amount of radiation. The amount of exposure is expressed in roentgens (R), whereas quantity of dose is expressed in rads.

radiation, relative biologic effectiveness of (RBE),

n a comparison between various types of ionizing radiation with respect to the ability to produce biologic effects with small doses.

radiation, remnant,

n the radiation passing through an object or part being examined that is available either for recording on a radiographic film or for measurement.

radiation, scattered,

n (backscatter radiation), radiation whose direction has been altered. It may include secondary and stray radiation.

radiation, secondary,

n the new radiation created by primary radiation acting on or passing through matter.

radiation shield,

n See shield, radiation.

radiation sickness,

n a self-limited syndrome characterized by varying degrees of nausea, vomiting, diarrhea, and psychic depression after exposure to very large doses of ionizing radiation, particularly doses to the abdominal region. Its mechanism is not completely understood. It usually occurs a few hours after treatment and may subside within a day. It may be sufficiently severe to necessitate interrupting the treatment series, or it may incapacitate the patient.

radiation, soft,

n radiation consisting of the long wavelengths (lower kilovolt peak results in less penetration).

radiation, speed of,

n the speed of light, or approximately 186,000 miles per second.

radiation, stray,

n See radiation leakage.

radiation survey,

n See survey, radiation.

radiation therapy,

n See therapy, radiation.

radiation, total body,

n the exposure of the entire body to penetrating radiation. In theory, all cells in the body receive the same overall dose.

radiation treatment,

n a cancer treatment method that uses roentgen rays to modify or destroy cancer cells; dental patients who are undergoing radiation therapy may exhibit an increased need for certain nutrients. See also therapy, radiation.

radiation, useful,

n the part of the primary radiation that is permitted to pass from the tube housing through the tube head port, aperture, or collimating device. See beam, useful.

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radiation

1. divergence from a common center.

2. a structure made up of diverging elements, especially a tract of the central nervous system made up of diverging fibers.

3. energy carried by waves or a stream of particles. One type is electromagnetic radiation, which consists of wave motion of electric and magnetic fields. The quantum theory is based on the fact that electromagnetic waves consist of discrete particles, called photons, that 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, which are emitted by radioisotopes of heavy elements, such as uranium. Beta particles are high-energy electrons, which are emitted by radioisotopes of lighter elements. Gamma rays are high-energy photons, which are emitted along with alpha and beta particles and are 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 ionizing radiation. This includes alpha and beta particles and x-rays and gamma rays.

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radiation biology

study of the effects of ionizing radiation on living tissues.

corpuscular radiation

particles emitted in nuclear disintegration, including alpha and beta particles, protons, neutrons, positrons and deuterons.

radiation detection

special equipment, including Geiger-Müller tubes and a scintillation crystal, is available to detect radiation which may be accidental, or detect small amounts where this is expected but it needs to be measured in terms of accumulated dose.

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.

radiation exposure

means more than the patient being exposed intentionally to an x-ray beam. Technical persons in the vicinity will also be exposed to a much less dangerous but perniciously cumulative load of radiation.

infrared radiation

the portion of the spectrum of electromagnetic radiation of wavelengths ranging between 0.75 and 1000 μm. See also infrared.

radiation injury

is caused by exposure to radioactive material. High doses cause intense diarrhea and dehydration and extensive skin necrosis. Median doses cause initial anorexia, lethargy and vomiting then normality for several weeks followed by vomiting, nasal discharge, dysentery, recumbency, septicemia and a profound pancytopenia. Death is the most common outcome. Chronic doses cause cataract in a few. Congenital defects occur rarely.

interstitial radiation

energy emitted by radium or radon inserted directly into the tissue.

ionizing radiation

corpuscular or electromagnetic radiation that is capable of producing ions, directly or indirectly, in its passage through matter. Used in treatment of radiosensitive cancer, in sterilization of animal products and food for experimental use.

radiation necrosis

see radionecrosis.

radiation physicist

the person responsible for the administration of radiation therapy including estimating the dose required for a treatment, arranging for the dose to be delivered and making arrangements for safety of the patient and staff, and disposing of any residual radioactive material. Technical aspects of the work include computer estimations, preparation of isodose curves, preparation of wedge and compensating filters, and calibration of teletherapy equipment.

primary radiation

radiation emanating from the x-ray tube which is absorbed by the subject or passes on through the subject without any change in photon energy.

radiation protection

includes proper control of emissions from the x-ray machines, proper protective clothing for staff, keeping unnecessary people out of the way while the tube is actually generating its beam, the wearing and regular examination of a dosimeter and the proper storage of radioactive materials or residues.

pyramidal radiation

fibers extending from the pyramidal tract to the cortex.

radiation sensitivity

tissues vary in their sensitivity to the damaging effects of irradiation. The rapidly growing tissues are most susceptible, e.g. the embryo, rapidly growing cancer, gonads, alimentary tract, skin and blood-forming organs.

radiation sickness

see radiation injury (above).

solar radiation

see solar.

radiation striothalamica

a fiber system joining the thalamus and the hypothalamic region.

tegmental radiation

fibers radiating laterally from the nucleus ruber.

thalamic radiation

fibers streaming out through the lateral surface of the thalamus, through the internal capsule to the cerebral cortex.

radiation therapist

a person skilled in radiotherapy. See also radiation therapy (below).

radiation therapy

see radiotherapy.

ultraviolet radiation

the portion of the spectrum of electromagnetic radiation of wavelengths ranging between 0.39 and 0.18 μm. See also ultraviolet rays.

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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.

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radiation

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

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Patient discussion about speed of radiation.

Q. I have a low back pain that radiates to my leg when i pick up stuff. Is it a disc herniation? I am a 43 years old bank teller. During the past 5 months I've suffered from a low back pain. The pain is not very strong, but it gets much worse while doing physical activity. When i walk or lift heavy things the pain is even stronger, and it radiates to my left leg. Can it be signs for disc herniation?

A. You can't tell for sure that your symptoms are due to a specific disc pathology.
When i had similar symptoms i went to the GP and he told me to lay down on your back. Then he slowly raised my left leg while the knee is kept in extension.
He said that If raising the leg over 60 degree exacerbates the pain its very likely to be disc herniation. But you should go to your GP and have him examine you.

Q. what does a sun block cream do? and what are a UV rays?

A. It blocks out harmful Ultra violet rays from the skin as the previous entries have related; however it can also block your ability to produce vitamin D. If you live in a northerly area or one that receives limited sunlight, its recommended to get at least 15 minutes of sun a day (this is probably best done with minimal sunblock) and according to personnal sun sensitivity. Another thing to keep in mind is that sunblock works best if applied 20 minutes before sun exposure.

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.