BINP SB RAS, Novosibirsk, Russia
Budker INP & NSU, Novosibirsk, Russia
NSU, Novosibirsk, Russia
A promising method of treatment of many malignant tumors is the boron neutron capture therapy (BNCT)*. It provides a selective destruction of tumor cells by prior accumulation of a stable boron-10 isotope inside them and subsequent irradiation with epithermal neutrons. It is expected that accelerator based neutron sources will be created for the clinical practice. One such source could be an original source of epithermal neutrons**, created in BINP. To obtain proton beam a new type of particle accelerator is used - tandem accelerator with vacuum insulation. Generation of neutrons is carried out as a result of the threshold reaction 7Li(p, n)7Be. During 2015-2016 in the construction of tandem accelerator with vacuum insulation several changes were made. This allowed us to suppress the unwanted flow of charged particles in the accelerator, to improve its high-voltage stability, and to increase the proton beam current from 1.6 to 5 mA. Such current value is sufficient for BNCT. The report describes in detail the modernization of the accelerator, presents and discusses the results of experiments on obtaining the proton beam and the formation of neutron flux using lithium target, and declares our prospective plans. The obtained neutron beam meets the requirements of BNCT: the irradiation of cell cultures provides the destruction of cells with boron and preservation of cells without boron. Irradiation of immunodeficient mice with grafted glioblastoma results in their recovery.
*Neutron Capture Therapy. Principles and Applications. Eds: W. Sauerwein, A. Wittig, R. Moss, Y. Nakagawa. Springer, 2012.
**S. Taskaev. Accelerator based epithermal neutron source. Physics of Particles and Nuclei 46 (2015) 956-990.
BINP SB RAS, Novosibirsk, Russia
In BINP the neutron source for BNCT based on proton accelerator was designed and built. It is necessary for the therapy to ensure a stable proton beam current of not less than 3 mA with energy 2 MeV. During the injection of negative hydrogen ion beam into the accelerator the unwanted charged particles are produced, affecting the stability of beam parameters. The article describes meth-ods of suppression of undesirable charged particles and the results of experiments.
THPSC034
BINP SB RAS, Novosibirsk, Russia
In the BINP SB RAS was created a source of epithermal neutrons for BNCT. The proton beam is obtained by stripping negative hydrogen inside gas target. Using the gas target leads to interaction of injected beam with gas and producing unwanted flow of electrons in accelerating channel. Occurred electrons are accelerated up to 1 MeV energy, bombard the electrodes and produce radiation. For suppressing of electrons, electrodes diaphragm with magnets was designed. Diaphragm was set on first electrode, where electrons have low (166 keV) energy. The field about 15 mT separate main beam particles and electrons on 2 components. Thus, the main beam passes freely through diaphragm and accelerates, and electrons beam, with low energy, land on the first electrode. This article shows that the setting of diaphragm with magnets conduct to ~30% decreasing of radiation dose. Also, we discussed negative sides and technical solutions of this modification, such as reducing of potential on first electrode by electrons or demagnetization magnets by the beam.