Radiation linear energy transfer

This chapter will focus on the influence of two essential parameters on the chemical mechanism of water under radiation Linear Energy Transfer and temperature. 

Modulation of the Killing of Mammalian Cells by Thiols. Important aspects of the effects of exogenous thiols on clonogenic cell survival following exposure to low linear energy transfer (LET) radiations include the following. 

Quality Factor (Q)—The linear-energy-transfer-dependent factor by which absorbed doses are multiplied to obtain (for radiation protection purposes) a quantity that expresses - on a common scale for all ionizing radiation - the approximate biological effectiveness of the absorbed dose. 

The range in tissues and linear energy transfer (LET) depend on the type of radiation emitted and its energy. The potent lethality of Auger and low-energy conversion electrons is demonstrated by intranuclear localization of the radioisotope due to their short ranges (about one cell nucleus in diameter). Alpha particles have ranges of several cell diameters (40-90 pm) and are effective in... 

Linear energy transfer (LET) A function of the capacity of the radiation to produce ionization. LET is the rate at which charged particles transfer their energies to the atoms in a medium and a function of the energy and velocity of the charged particle. See Radiation dose. 

Linear Energy Transfer. The concept of linear energy transfer (LET) has been a useful one in rationalising the variation in radiolytic yields found for different types of radiation. It is still widely... 

Because of the high linear energy transfer (LET) of the particles produced by the 10B(n,a)7Li reaction, the production of secondary ions is not enhanced in the presence of oxygen with low-LET radiation such as external photon irradiation, tissues... 

E = 137keV). The accompanying emission of 7-radiation can be used for scintigraphic imaging but also makes patient isolation necessary. The different half-lifes and /3 -energies allow individual therapeutic demands such as the pharmacokinetics of the tracer molecule, the linear energy transfer of the nuclides or the biodistribution and clearance of the radiolabeled drug to be met. The principles of the application of radioactive materials for therapy are summarized in an excellent review. ... 

Radiation quality is defined by the nature, charge, and energy spectrum of the particles and can be characterized by the linear energy transfer (LET) or, alternatively, by the micro-dosimetric spectra at the point of interest under the actual irradiation conditions. 

The radiobiological rationale for introducing high linear energy transfer (LET) radiation in cancer therapy, as proposed in the 1960s, is still valid and has not been contradicted by more recent radiobiological findings [3]. 

The National Coimdl on Radiation Protection and Measurements (NCRP) has been concerned from its inception with assessment of the risks of low-level irradiation. In recent years, this concern has prompted increasingly detailed efforts to quantify the influence of dose, dose rate, and linear energy transfer (LET) on the biomedical effects of radiation, with particular reference to the carcinogenic risks of low-level exposure (NCRP, 1980) and the work-in-progress of NCRP Sdentific Committee 40 on LET and relative biological effectiveness. 

The stopping power of a material for a particular radiation is commonly expressed as the rate of energy loss (R.E.L.) or the linear energy transfer (L.E.T.) of the radiation in the material. These quantities are assumed to be proportional to the linear ion density and the specific ionization. Stopping powers range from approximately 106 e.v./cm. for fast electrons (1 Mev.) in water to 1011 e.v./cm. for fission recoils. The ranges of particles are frequently expressed in mg./cm.2, which when multiplied by the density of the material yields the range. 

Then, a major part of these radicals would be consumed by chain termination to form corresponding alcohols and ketones. Yokohata and Tsuda (23, 24, 25) have suggested that the silent discharge reaction can well be interpreted in terms of radiolysis caused by the ionizing radiation of high LET (Linear Energy Transfer), and this would help explain the short chains of this oxidation. 

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