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Megarad
The rad is a unit of absorbed radiation dose, defined as 1 rad = 0.01 Gy = 0.01 J/kg. It was originally defined in CGS units in 1953 as the dose causing 100 ergs of energy to be absorbed by one gram of matter. The material absorbing the radiation can be human tissue, air, water, or any other substance. It has been replaced by the gray (symbol Gy) in SI derived units, but is still used in the United States, although this is "strongly discouraged" in Chapter 5.2 of the ''Guide to the SI'', which was written and published by the U.S. National Institute of Standards and Technology. However, the numerically equivalent SI unit submultiple, the centigray (symbol cGy), is widely used to report absorbed doses within radiotherapy. The roentgen, used to quantify the radiation exposure, may be related to the corresponding absorbed dose by use of the F-factor. Health effects A dose of under 100 rad will typically produce no immediate symptoms other than blood changes. A dose of 100 to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Absorbed Dose
Absorbed dose is a dose quantity which is the measure of the energy deposited in matter by ionizing radiation per unit mass. Absorbed dose is used in the calculation of dose uptake in living tissue in both radiation protection (reduction of harmful effects), and radiology (potential beneficial effects for example in cancer treatment). It is also used to directly compare the effect of radiation on inanimate matter such as in radiation hardening. The SI unit of measure is the Gray (unit), gray (Gy), which is defined as one Joule of energy absorbed per kilogram of matter. The older, non-SI Centimetre–gram–second system of units, CGS unit rad (unit), rad, is sometimes also used, predominantly in the USA. Deterministic effects Conventionally, in radiation protection, unmodified absorbed dose is only used for indicating the immediate health effects due to high levels of acute dose. These are tissue effects, such as in acute radiation syndrome, which are also known as deterministic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
William Valentine Mayneord
William Valentine Mayneord, CBE FRS (14 February 1902 – 10 August 1988) was a British physicist and pioneer in the field of medical physics. Early life and education He was born in Redditch, Worcestershire to Walter and Elizabeth Mayneord but after the early death of his mother was adopted by an aunt in Evesham. He was educated at Prince Henry's School, Evesham and gained a Bachelor of Science at the University of Birmingham Career He entered the field of medical physics in 1924 at St Bart's Hospital in London. In 1927 he moved to the Cancer Hospital, now the Royal Marsden Hospital. There he was involved in pioneering work with Izrael Hieger. During World War II he was seconded by the government to work in Canada on the radiological aspects of atomic energy development. It has been said that such was his renown, especially for bringing in the use of the radiological unit the rad, that the SI unit may well have been called the mayneord instead of the gray (2). It was d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Louis Harold Gray
Louis Harold Gray FRS (10 November 1905 – 9 July 1965) was an English physicist who worked mainly on the effects of radiation on biological systems. He was one of the earliest contributors of the field of radiobiology. A summary of his work is given below. Amongst many other achievements, he defined a unit of radiation dosage which was later named after him as an SI unit, the gray. Career * 1933 - Hospital physicist at Mount Vernon Hospital, London * 1936 - Developed the Bragg–Gray equation, the basis for the cavity ionization method of measuring gamma-ray energy absorption by materials * 1937 - Built an early neutron generator at Mount Vernon Hospital * 1938 - Studied biological effects of neutrons using the generator * 1940 - Developed concept of RBE (Relative Biological Effectiveness) of doses of neutrons * 1952 - Initiated research into cells in hypoxic tumors and hyperbaric oxygen * 1953 - Established the British Empire Cancer Campaign Research Unit in Radiobiolo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wood River Junction, Rhode Island
Wood River Junction is a small village in the town of Richmond, Rhode Island, Washington County, Rhode Island, in the United States. It is home to the Chariho school district's main campus and is otherwise largely turf farms. Geography Wood River Junction is commonly considered by locals to be one of the coldest locations in the state of Rhode Island, due to its low-lying and flat geography. It is the home of Meadowbrook Pond, also known as Wood River Pond, a popular fishing area. It is surrounded by two rivers: the Wood River and Pawcatuck River. History Overview The village was the site of Wood River Junction station, originally known as Richmond Switch. The Wood River Branch Railroad was chartered in 1872 and completed in 1874. The name was changed in April 1874. The six-mile branch line was built to provide service from the Hope Valley to the main line of the New York, Providence and Boston Railroad and was only six miles long. The New York, New Haven and Hartford Railroad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radiotherapy
Radiation therapy or radiotherapy, often abbreviated RT, RTx, or XRT, is a therapy using ionizing radiation, generally provided as part of cancer treatment to control or kill malignant cells and normally delivered by a linear accelerator. Radiation therapy may be curative in a number of types of cancer if they are localized to one area of the body. It may also be used as part of adjuvant therapy, to prevent tumor recurrence after surgery to remove a primary malignant tumor (for example, early stages of breast cancer). Radiation therapy is synergistic with chemotherapy, and has been used before, during, and after chemotherapy in susceptible cancers. The subspecialty of oncology concerned with radiotherapy is called radiation oncology. A physician who practices in this subspecialty is a radiation oncologist. Radiation therapy is commonly applied to the cancerous tumor because of its ability to control cell growth. Ionizing radiation works by damaging the DNA of cancerous ti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Erythema
Erythema (from the Greek , meaning red) is redness of the skin or mucous membranes, caused by hyperemia (increased blood flow) in superficial capillaries. It occurs with any skin injury, infection, or inflammation. Examples of erythema not associated with pathology include nervous blushes. Types * Erythema ab igne * Erythema chronicum migrans * Erythema induratum * Erythema infectiosum (or fifth disease) * Erythema marginatum * Erythema migrans * Erythema multiforme (EM) * Erythema nodosum * Erythema toxicum * Erythema elevatum diutinum * Erythema gyratum repens * Keratolytic winter erythema * Palmar erythema Causes It can be caused by infection, massage, electrical treatment, acne medication, allergies, exercise, solar radiation (sunburn), photosensitization, acute radiation syndrome, mercury toxicity, blister agents, niacin administration, or waxing and tweezing of the hairs—any of which can cause the capillaries to dilate, resulting in redness. Erythema i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unit Multiple
A base unit of measurement (also referred to as a base unit or fundamental unit) is a unit of measurement adopted for a ''base quantity''. A base quantity is one of a conventionally chosen subset of physical quantities, where no quantity in the subset can be expressed in terms of the others. The SI base units, or ''Systeme International d'unites'', consists of the metre, kilogram, second, ampere, kelvin, mole and candela. A unit multiple (or multiple of a unit) is an integer multiple of a given unit; likewise a unit submultiple (or submultiple of a unit) is a submultiple or a unit fraction of a given unit. ''Unit prefixes'' are common base-10 or base-2 powers multiples and submultiples of units. While a base unit is one that has been explicitly so designated, a derived unit is unit for a '' derived quantity'', involving the combination of quantities with different units; several ''SI derived units'' are specially named. A ''coherent derived unit'' involves no conversion factor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metric Prefix
A metric prefix is a unit prefix that precedes a basic unit of measure to indicate a multiple or submultiple of the unit. All metric prefixes used today are decadic. Each prefix has a unique symbol that is prepended to any unit symbol. The prefix '' kilo-'', for example, may be added to ''gram'' to indicate ''multiplication'' by one thousand: one kilogram is equal to one thousand grams. The prefix ''milli-'', likewise, may be added to ''metre'' to indicate ''division'' by one thousand; one millimetre is equal to one thousandth of a metre. Decimal multiplicative prefixes have been a feature of all forms of the metric system, with six of these dating back to the system's introduction in the 1790s. Metric prefixes have also been used with some non-metric units. The SI prefixes are metric prefixes that were standardised for use in the International System of Units (SI) by the International Bureau of Weights and Measures (BIPM) in resolutions dating from 1960 to 2022. Since 2009, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gamma Ray
A gamma ray, also known as gamma radiation (symbol γ or \gamma), is a penetrating form of electromagnetic radiation arising from the radioactive decay of atomic nucleus, atomic nuclei. It consists of the shortest wavelength electromagnetic waves, typically shorter than those of X-rays. With frequency, frequencies above 30 exahertz (), it imparts the highest photon energy. Paul Ulrich Villard, Paul Villard, a French chemist and physicist, discovered gamma radiation in 1900 while studying radiation emitted by radium. In 1903, Ernest Rutherford named this radiation ''gamma rays'' based on their relatively strong penetration of matter; in 1900 he had already named two less penetrating types of decay radiation (discovered by Henri Becquerel) alpha particle, alpha rays and beta particle, beta rays in ascending order of penetrating power. Gamma rays from radioactive decay are in the energy range from a few kiloelectronvolts (keV) to approximately 8 megaelectronvolts (MeV), corres ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X-ray
X-rays (or rarely, ''X-radiation'') are a form of high-energy electromagnetic radiation. In many languages, it is referred to as Röntgen radiation, after the German scientist Wilhelm Conrad Röntgen, who discovered it in 1895 and named it ''X-radiation'' to signify an unknown type of radiation.Novelline, Robert (1997). ''Squire's Fundamentals of Radiology''. Harvard University Press. 5th edition. . X-ray wavelengths are shorter than those of ultraviolet rays and longer than those of gamma rays. There is no universally accepted, strict definition of the bounds of the X-ray band. Roughly, X-rays have a wavelength ranging from 10 nanometers to 10 picometers, corresponding to frequencies in the range of 30 petahertz to 30 exahertz ( to ) and photon energies in the range of 100 eV to 100 keV, respectively. X-rays can penetrate many solid substances such as construction materials and living tissue, so X-ray radiography is widely used in medi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stochastic
Stochastic (, ) refers to the property of being well described by a random probability distribution. Although stochasticity and randomness are distinct in that the former refers to a modeling approach and the latter refers to phenomena themselves, these two terms are often used synonymously. Furthermore, in probability theory, the formal concept of a '' stochastic process'' is also referred to as a ''random process''. Stochasticity is used in many different fields, including the natural sciences such as biology, chemistry, ecology, neuroscience, and physics, as well as technology and engineering fields such as image processing, signal processing, information theory, computer science, cryptography, and telecommunications. It is also used in finance, due to seemingly random changes in financial markets as well as in medicine, linguistics, music, media, colour theory, botany, manufacturing, and geomorphology. Etymology The word ''stochastic'' in English was originally used as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
