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BNCTBoron neutron capture therapy (BNCT) is an experimental form of radiosurgerythat utilizes a neutronbeam that interacts with boroninjected to a patient. BNCT depends on the interaction of slow neutrons with boron-10 to produce alpha particles, another type of radiation. Patients are first given an intravenous injection of a boron-10 tagged chemical that preferentially binds tumor cells. The neutrons are created either in a nuclear reactoror by colliding high-energy protons into a Lithium target. The neutrons pass through a moderator, which shapes the neutron energy spectrum suitable for BNCT treatment. Before entering the patient the neutron beam is shaped by a beam collimator. While passing through the tissue of the patient, the neutrons are slowed by collisions and become low energy thermal neutrons. The thermal neutrons undergo reaction with the boron-10 nuclei, forming an unstable boron-11 nucleus which then undergoes spontaneous decay to lithium-7 and an alpha particle. Both the alpha particle and the lithium ion produce closely spaced ionizations in the immediate vicinity of the reaction, with a range of approximately 10 micrometres, or one cell diameter. This technique is advantageous since the radiation damage occurs over a short range and thus normal tissues can be spared. Also, there are two mechanisms for tumor selectivity, since both the boron compound is made to bind to tumor cells and the neutron beam is aimed at the location of the tumor. BNCT has been experimentaly tested primarily as an alternative treatment for malignant brain tumors called glioblastomas. Although there are reports of some successful outcomes, this approach has not yet been shown to be superior to other current therapies. Hence, BNCT has not entered routine clinical use. External links
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