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Auger therapy
Auger therapy (AT) is a form of radiation therapy for the treatment of cancer which relies on a large number of low-energy electrons (emitted by the Auger effect) to damage cancer cells, rather than the high-energy radiation used in traditional radiation therapy.〔〔Persson, L. The Auger Electron Effect in Radiation Dosimetry – A Review. Swedish Radiation Protection Institute, S-17116 Stockholm, Sweden.〕 Similar to other forms of radiation therapy, Auger therapy relies on radiation-induced damage to cancer cells (particularly DNA damage) to arrest cell division, stop tumor growth and metastasis and kill cancerous cells. It differs from other types of radiation therapy in that electrons emitted via the Auger effect (Auger electrons) are released in large numbers with low kinetic energy. Because of their low energy, these electrons damage cells over a very short range: less than the size of a single cell, on the order of nanometers.〔 This very short-range delivery of energy permits highly targeted therapies, since the radiation-emitting nuclide is required to be inside the cell to cause damage to its nucleus. However, this is a technical challenge; Auger therapeutics must enter their cellular targets to be most effective.〔〔 Auger therapeutics are small molecules, capable of entering cells of interest and binding to specific sub-cellular components, which contain one (or more) heavy atoms capable of emitting Auger electrons by radioactive decay or external excitation.〔
==Auger dose ==
The electron energy in a vacuum may be accurately measured with an electron detector in a Faraday cage, where the bias placed on the cage will accurately define the particle energy reaching the detector. The range of low-energy electrons in tissue or water, particularly electrons at the nm scale, cannot be easily measured; it must be inferred, since low-energy electrons scatter at large angles and travel in a zigzag path whose termination distance must be considered statistically and from differential measurements of higher-energy electrons at a much higher range. A 20-electronvolt (eV) electron in water, for example, could have a range of 20 nm for 103 gray or 5 nm for 104.7 gray. For a group of 9-12 Auger electrons with energies at 12-18 eV in water (including the effect of water ionization at approximately 10 eV), an estimate of 106 gray is probably sufficiently accurate. The illustration shows the simulated dose calculation in water for an electron using a Monte Carlo random walk〔J.Messungnoenab et al, Radiation Research 158, 657-660; 2002〕 which gives up to 0.1 MGy. For a moderately-heavy atom to yield a dozen or more Auger electrons from its inner-shell ionization, the Auger dose becomes 106 gray per event.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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