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Topic: Linear energy transfer

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In the News (Wed 19 Jun 19)

  Linear energy transfer
Term in dosimetry of ionizing rays; energy transfer of an ionizing particle to the matter penetrated by radiation.
The linear energy transfer is equal to the energy dE which a charged particle loses at a distance dl.
The linear energy transfer is indicated in keV/µm.
www.euronuclear.org /info/encyclopedia/l/linearenergytransfer.htm   (108 words)

 linear energy transfer
Linear energy transfer (LET) is used to quantify the effects of ionizing radiation on biological specimens or electronic devices.
LET varies enormously depending on the speed and charge of the particle involved.
This is because high LET radiation can deposit most of its energy within the volume of one cell of the body and the chance of damage to the cell DNA is therefore larger.
www.daviddarling.info /encyclopedia/L/linear_energy_transfer.html   (147 words)

 Effects of ingesting radionuclides
The deposition of energy is called absorbed dose and is one of the factors that determines the biological effect.
For gamma rays, the linear energy transfer is very low, for as already mentioned, they mostly escape from the body leaving behind a very little bit of their energy.
Alpha particles have the highest linear energy transfer and, for any given absorbed dose, are about 20 times as effective at producing biological effects as are gamma rays.
www.hps.org /publicinformation/ate/q806.html   (856 words)

 RAF310 - Radiation Biology - Multiple choice questions
Linear energy transfer (LET) is the energy transferred to the biologic material per unit mass of the material.
LET is the quotient dE/dl, where dE is the energy that a particle lost in causing an ionization and dl is the distance that the ionizing particle travels between two ionizations.
LET is the quotient dE/dl, where dE is the average energy locally imparted to the medium by a charged particle when the particle has traversed a distance dl.
www.hep.lu.se /staff/c.jarlskog/hall/chapter7.html   (568 words)

 Kinetic energy - Encyclopedia.WorldSearch   (Site not responding. Last check: 2007-11-02)
The kinetic energy of a body is equal to the amount of work needed to establish its velocity and rotation, starting from rest.
Relativity theory states that the kinetic energy of an object grows towards infinity as its velocity approaches the speed of light, and thus that it is impossible to accelerate an object to this boundary.
The relationship between heat, temperature and kinetic energy of atoms and molecules is the subject of statistical mechanics.
encyclopedia.worldsearch.com /kinetic_energy.htm   (645 words)

 Department of Energy - Homepage
The Department of Energy is aware of suspicious activity, involving a phishing email scam, targeting the general public.
Conduct an energy audit of your home to find air leaks and to check for the proper level of insulation.
ENERGY STAR computers and monitors save energy only when the power management features are activated, so make sure power management is activated on your computer.
www.energy.gov   (3450 words)

 Nat' Academies Press, Radiation Hazards to Crews of Interplanetary Missions: Biological Issues and Research Strategies ...   (Site not responding. Last check: 2007-11-02)
Gray: SI unit of absorbed dose, equal to the energy transferred by ionizing radiation to a mass of matter corresponding to 1 J/kg (equals 100 rad).
Low linear energy transfer (LET) radiation is characterized by light charged particles such as electrons produced by x rays and gamma rays where the distance between ionizing events is large on the scale of a cellular nucleus.
High linear energy transfer (LET) radiation is characterized by heavy charged particles such as alpha particles and heavy nuclei, where the distance between ionizing events is small on the scale of a cellular nucleus.
books.nap.edu /openbook/0309056985/html/63.html   (3263 words)

Rate of energy dissipation along the path of charged particles.
The mean energy imparted to a medium by a charged particle along a small element of its path, due to collisions with energy transfers less than some specified value, divided by the length of that element.
trasferimento lineico di energia (restricted linear collision stopping power), trasferimento lineare di energia (energy locally imparted, restricted linear collision stopping power), potere frenante lineare ristretto per collisione (energy locally imparted, restricted linear collision stopping power).
www.websters-online-dictionary.org /definition/english/li/linear+energy+transfer.html   (326 words)

 WPI Environmental and Occupational Safety - Radiation Safety Training and Reference Manual   (Site not responding. Last check: 2007-11-02)
The energy of the radiation emitted is a characteristic of the radionuclide.
Dose is a measure of energy deposited by radiation in a material, or of the relative biological damage produced by that amount of energy given the nature of the radiation.
For a point source gamma emitter with energies between 0.07 and 2 MeV, the exposure rate in R/hr at 1 foot is approximately 6 x C x E x n, where C is the activity in curies; E is the energy in MeV; and n is the number of gammas per disintegration.
www.wpi.edu /Admin/Safety/RSO/Training/trm.html   (11507 words)

 CT 7/97 Industrial-size photobioreactors   (Site not responding. Last check: 2007-11-02)
During the linear growth phase, the cell concentration in the photobioreactor is fairly high, so depending on the depth of the reactor, almost all the supplied light energy is absorbed by the growing cells.
s, the linear growth rate and the final cell concentration increased relative to the light supply coefficient; however, as expected, the efficiency of the cell's use of the supplied light energy decreased.
Use of solar energy is obviously desirable, because it is abundant and free.
pubs.acs.org /hotartcl/chemtech/97/jul/ind.html   (4366 words)

 LET dependence of a polymer gel dosimeter
Linear energy transfer dependence of a normoxic polymer gel dosimeter investigated using proton beam absorbed dose measurements
The purpose of this study was to investigate possible LET dependence for a polymer gel dosimeter using proton beam absorbed dose measurements.
The LET distribution for a monoenergetic proton beam was calculated as a function of depth using the Monte Carlo code PETRA.
stacks.iop.org /0031-9155/49/3847   (392 words)

 COLA Report 60   (Site not responding. Last check: 2007-11-02)
Vertically integrated kinetic energy, enstrophy, rotational non-linear interactions and the baroclinic source term are diagnosed as a function of total wave number n, and in terms of contributions of low and high frequencies.
This transfer is quite variable, with very roughly 16% of ten-day periods yielding a tendency twice the mean, and 16% showing no upscale tendency whatever.
(f) The main seasonal effects are a dramatic weakening in summer of the total energy and shifting to higher wave number of the peak, and a distinct shift to higher scales in the transition between the large-scale and synoptic-scale regimes in the energy budget.
grads.iges.org /reps/rep60/colarep60.html   (360 words)

 7_2.3 Linear Energy Transfer
The Linear Energy Transfer (LET) is similar to the stopping power except that it does not include the effects of radiative energy loss (i.e., Bremsstrahlung) or delta-rays.
The difference between LET and S is that LET is local energy deposition only and S is concerned with the total energy lost by the particle.
Positrons behave nearly the same as electrons as they lose their energy, they are simply deflected in the opposite direction.
www.med.harvard.edu /JPNM/physics/nmltd/radprin/sect7/7.2/7_2.3.html   (244 words)

 6. ACIS : Advanced CCD Imaging Spectrometer   (Site not responding. Last check: 2007-11-02)
The low energy response of ACIS has also been affected by the build-up of a contaminant on the optical blocking filters and this is discussed in Section 6.5.1.
Since the ideal focal surface depends on energy, observers, for whom such considerations may be important, are urged to make use of the MARX simulator to study the impact on their observation.
The pre-launch energy resolution as a function of energy is shown in Figure 6.10.
cxc.harvard.edu /proposer/POG/html/ACIS.html   (9924 words)

 College of Engineering VII - BU 2004/2005 Undergraduate Bulletin
These transforms are applied to the analysis of linear systems; sampled signals and systems; digital filtering; solution of partial differential equations, and antenna theory; two-dimensional systems; optics; medical imaging; mechanical systems; and statistics.
Numerical solution of systems of linear and non-linear algebraic equations, interpolation and extrapolation, computation of eigenvalues and eigenvectors, numerical integration, techniques for numerical solution of ordinary differential equations and partial differential equations.
The nucleic acids, DNA and RNA, linear formation storing structure, as well as their three-dimensional structure, are covered in relationship to their function.
www.bu.edu /bulletins/und/item19g7.html   (10543 words)

 Transfer Factor Scientific Studies -- 1990
Aggregation of the epidermal growth factor receptor was measured by determining the increase in fluorescence energy transfer between receptor-bound fluorescein and tetramethylrhodamine-labeled epidermal growth factor.
Energy transfer between receptor-bound fluorescent derivatives was reversibly greater at 37 than 4 degrees C, indicating temperature-dependent aggregation of the receptor.
The transfer by the suckling rat jejunum and ileum was significantly inhibited by the presence of dinitrophenol and sodium azide or by the replacement of sodium with potassium or choline, RP-HPLC analysis detected carboxy-terminal processing of 125I-mEGF in suckling and adult rat jejunum and ileum.
www.emmessar.com /colostrum/0/A/Research/research25.htm   (9008 words)

 Radiation Therapy Facts and Information
Ionizing radiation deposits energy that injures or destroys cells in the area being treated (the "target tissue") by damaging their genetic material, making it impossible for these cells to continue to grow.
Depending on the amount of energy they possess, the rays can be used to destroy cancer cells on the surface of or deeper in the body.
Linear accelerators and betatrons are machines that produce x-rays of increasingly greater energy.
www.cancercompass.com /cancer-news/1,515,00.htm   (879 words)

 Nuclear Radiation and its Biological Effects: Linear Energy Transfer (LET), from "No Immediate Danger, Prognosis for a ...
Measurement of the number of ionisations which radiation causes per unit distance as it traverses the living cell or tissue is called the linear energy transfer of the radiation.
The density of ionisation causes special problems in sperm and ova because the damage (protein breakage) is concentrated within a few cells.
A comparable 1 rad exposure to neutrons which have higher linear energy transfer (LET) would be expected to cause more cell deaths and more mutations.
www.ratical.org /radiation/NRBE/NRBE7.html   (961 words)

 ICRU News
In conclusion, the mentioned physical dimension analysis is correct, but with regard to the proposed change of the term "stopping power" into "stopping force" it is a weak argument compared with the sum of the opposite linguistic, physical and organisational arguments and should therefore be given second priority.
What is really done in radiobiology and radiation protection is different: "linear energy transfer" is identified with the collision stopping power of water, and "restricted linear energy transfer" is identified with the restricted collision stopping power of water.
Therefore, ICRU's definition of "linear energy transfer", although thoughtfully coined and not illogic in itself, is in a long-standing contradiction to the established worldwide terminology in the field.
www.icru.org /n_002_5.htm   (691 words)

 What Types of Radiation Treatment are Available   (Site not responding. Last check: 2007-11-02)
Photon and Electron radiation are produced with a linear accelerator, a betatron or from radioactive sources such as cobalt.
Gamma ray is a form of photons produced from the decay of certain elements or radioactive isotopes such as radium, uranium and cobalt 60.
Neutrons, pions and heavy ions (such as carbon, neon and argon) deposit more energy along their path than x-rays or gamma rays, thus causing more damage to the cells they hit.
www.orgsites.com /ca/acco/WhatTypesofRadiationTreatmentareAvailable.htm   (382 words)

 MSN Encarta - Search Results - linear energy transfer
Heat Transfer, in physics, process by which energy in the form of heat is exchanged between bodies or parts of the same body at different...
Energy : energy and physics: rate of transfer
Power (physics), in physics and engineering, the rate of performing work or transferring energy.
encarta.msn.com /linear%2benergy%2btransfer.html   (183 words)

 Glossary J - L
is the sum of the initial kinetic energies of all charged ionizing particles liberated by uncharged ionizing particles in a material of mass dm.
where dE is the energy lost in traversing distance dl and D is an upper bound on the energy transferred in any single collision.
A measure of how, as a function of distance, energy is transferred from radiation to the exposed matter.
www-ns.iaea.org /tutorials/regcontrol/intro/glossaryj_l.htm   (1743 words)

 How particles can be therapeutic (August 2003) - Physics World - PhysicsWeb
Moreover, by combining protons with different energies in a single beam, the Bragg peak can be modulated into a plateau that dumps a high dose of radiation throughout the depth of the tumour.
This is because the rate at which a charged particle loses energy in a material - which is quantified by its linear energy transfer (LET) - increases with the mass of the particle.
Neutrons therefore have a higher linear energy transfer than charged particles, and can produce a RBE that is up to three times that of protons or ions.
www.physicsweb.org /article/world/16/8/9   (1656 words)

 Faculty: Jay LaVerne (Radiation Laboratory - University of Notre Dame)   (Site not responding. Last check: 2007-11-02)
The yields of excited states are found to decrease with increasing particle linear energy transfer, LET, because of intratrack quenching.
Heavy Ion Radiolysis of Water at Very High LET — Radical yields in the radiolysis of water with very high linear energy transfer (LET) 58Ni and 238U ions are substantially higher than previously expected from extrapolation of data with lower LET particles.
Even though these particles have LET of up to 104 eV/nm they also have a relatively high velocity which tends to expand the particle track and more radicals are able to escape intratrack combination reactions.
www.rad.nd.edu /faculty/laverne.htm   (335 words)

 SEI: Workshop Descriptions
With a focus on how-to build energy efficient, sustainable solar homes, everyone from the serious owner-builder to the professional contractor, will learn up-to-date strategies for sustainable new home construction and remodels.
Effective technology transfer methods will be presented, as well as setting up infrastructure and the economics and financing of renewable energy projects.
These workshops are for teachers and educators who want to learn how to implement renewable energy curriculum into their classrooms.
www.solarenergy.org /workshops   (3082 words)

 High-Linear Energy Transfer Irradiation Targeted to Skeletal Metastases by the {alpha}-Emitter 223Ra: Adjuvant or ...
High-Linear Energy Transfer Irradiation Targeted to Skeletal Metastases by the {alpha}-Emitter 223Ra: Adjuvant or Alternative to Conventional Modalities?
High-Linear Energy Transfer Irradiation Targeted to Skeletal Metastases by the
Copyright © 2006 by the American Association for Cancer Research.
clincancerres.aacrjournals.org /cgi/content/abstract/12/20/6250s   (287 words)

 Systems Biology at PNNL - Mechanisms of 3D Intercellular Signaling   (Site not responding. Last check: 2007-11-02)
Using this novel imaging tool, the team investigating the Mechanisms of Three-Dimensional Intercellular Signaling in Mammary Epithelial Cells in Response to Low Dose, Low Linear Energy Transfer (LET) Radiation is visualizing radiation-induced bystander signaling in 3-D cell cultures in situ.
The long-term consequences of the low LET RIBE in both 2- and 3-D culture will be examined by mixing irradiated and non-irradiated cells.
The effect of dose and the proportion of irradiated cells on cell survival and growth, cell differentiation, activation of signaling pathways, and the pattern of gene induction will be determined.
www.sysbio.org /sysbio/stress/3dsignaling.stm   (552 words)

 Synthesis, electron and energy transfer in triarylamines with linear and dendritic structure   (Site not responding. Last check: 2007-11-02)
The aim of the project is the synthesis of linear or branched pi-electron systems that have two or more triarylamine redox centres.
The energies of the redox centres are tuned so as to allow a directed electron or energy transfer, respectively.
Using linear model compounds we could show that the energy of the bridge connecting two redox centres is decisive for the electron transfer.
www.zv.uni-wuerzburg.de /forschungsbericht/FOBE-akt/LS-80032300/Triarylamine-E.htm   (97 words)

 [No title]   (Site not responding. Last check: 2007-11-02)
Experiments utilizing both aerated and deaerated solutions indicate that at the very high values of linear energy transfer (LET) exhibited by these ions in water (a maximum of 5000 and 17 000 eV/nm, respectively) a significant fraction of radicals escape from the track.
The radiation chemical yield of H atoms for both ions is found to be ~10% of the value with fast electrons.
A comparison of the results with particles of lower LET is made.
allen.rad.nd.edu /new_pubs/ndrl3937.htm   (145 words)

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