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Neutrons Against Cancer

Bombardment of a tumor with neutron flux is one of the most promising methods of radiation therapy. Wide application of fast neutron therapy (FNT) is complicated by the fact that it uses large neutron sources, requiring construction of individual facilities (nuclear reactors, accelerators, generators). Specialists of the Dukhov All-Russian Scientific Research Institute of Automation (VNIIA)have developed a neutron generator with the length of 1 m. The device is installed in any radiationproof room, which means that all major cities in Russia may be secured with this equipment. Coordination of the project involves Rosatom-owned AtomMed LLC, created to commercialize the knowledge-based development organizations of nuclear and allied industries in the field of nuclear medicine and radiation technologies. The State Atomic Energy Corporation Rosatom deals with financing, and all experimental studies are conducted on the basis of the Medical Radiological Research Center (MRRC) in Obninsk. On Thursday, March 3, 2011, the MRRC held a ceremony of the first physical launch of the compact neutron generator for teleirradiation FNT.

Two white rats were the first who experienced FNT. The very launch was implemented by Sergei Syromukov, head of the laboratory of the Dukhov All-Russian Scientific Research Institute of Automation. The process of tumor irradiation did not last more than a minute.

In the near future it is planned to organize dosimetric and radiobiological research. In particular, parameters of neutron irradiation and its effectiveness in destruction of tumors will be tested on biological objects. "The main advantage of this generator is its in-clinic placement, the generator can be placed in any radiation therapy clinic, allowing the FNT conducted for a larger number of patients needing this type of treatment," - head of department of Radiation Biophysics MRRC Stepan Ulyanenko said. According to S. Ulyanenko each year in Russia around half a million people become cancer carriers, and about 15-20% of them have neglected radioresistant cancers, which are very poorly amenable to traditional methods of treatment and require combined methods. "Fast neutron therapy is 3-4 times more efficient than conventional therapy" - he stressed. "There are three aspects of this event, three levels of challenges facing the nuclear industry of Russia," Deputy Director General of Rosatom Peter Shchedrovitsky said. Firstly, there are some forms of cancer, which can be treated only with FNT. The second level of objectives is creation of such hardware systems that would be at a level that even surpasses world counterparts. The third level - creation of services infrastructure through such facilities, Deputy Director General of Rosatom said. According to the director of AtomMed LLC Alexander Kuznetsov, today's launch is a point of shift from scientific development to experimental work." We will develop a strategy for entering global markets and abroad ", - he said. According to experts, serial sample will cost $1.3-1.5 million. It is hoped that many major medical centers will be able to acquire the neutron generator. Operation of the generator is based on the interaction of deuterium and tritium (2H and 3H), heavy isotopes of hydrogen. Under the action of powerful electric discharge deuterium molecules are ionized - disintegrate into an electron and deuteron, a particle consisting of a

proton and a neutron. "The reaction is using a deuteron, which strikes tritium, Anatoly Lychagin, Head of Laboratory of Medical Radiation Physics MRRC explains. - Dayton plus tritium give 5He, which quickly decays, emitting a neutron and atom of helium. The reaction proceeds with heat emission, so a neutron is emitted with energy, depending on the angle from 13 to 15.5 MeV". Such a reaction is used in many neutron generators. The feature of the new device is that gaseous tritium is received by the titanium target, therefore, to remove excess of tritium constructing an unwieldy system of pumping does not needed. "This generator has a tube which is completely sealed. In fact, even if you start hammering it, eject from there, from the generator and smash, anyway tritium will not get out because it is in the solid state there, - Sergey Syromukov, Head of Laboratory VNIIA says. - This solution allows you to drastically reduce the size of the neutron generator, and to increase its safety." During the FNT cancer cells are damaged due to high linear energy transfer of neutrons. Flying at high speed particles collide with molecules contained in cancer cells and damage them. For example, a stream of particles can lead to the disintegration of water molecules into protons and hydroxyl radicals, which, in turn, react with biopolymers and cause cell death. Developers of the generator suggest that in future it can be used for other types of treatment neutron capture therapy. This method involves the use of thermal neutrons with low energy (about 0.025 eV). Such neutrons can be absorbed by the boron atoms previously introduced into the tumor, with the release of large amounts of energy and the formation of alpha particles and lithium nucleus. This kind of therapy is highly effective and almost harmless to healthy tissue surrounding the tumor, but today it almost never used because of technical difficulties associated with obtaining neutrons with the needed energy. Trials of the new neutron generator, like any new device or drug will start from work on cell cultures. At this point, you can assess how well radiation is generated by the installation, kills tumor cells, and explores how it can affect healthy cells. The next phase of the project implementation will start within a year, when construction of the medical installations for FNT, including a system of local defense delivery system of the neutron beam to the patient, the patient positioning system and treatment planning will begin on the basis of modified during the assay compact neutron generator, and preparing to release a prototype of a therapeutic installation, which will become the prototype of the series. Scientists plan to study how effective a combination of FNT with gamma radiation particles will be. "Thus, it is possible to avoid skin reactions, which are characteristic for the pure neutron radiation, but because neutrons can treat radioresistant tumors, in which "the only gamma" does not give such an effect", - Sergey Koryakin, Senior Researcher, Laboratory of Radiation Biophysics MRRC says. Medical-biological trials will improve the compact neutron generator. After that it will be staffed by security systems of the surrounding tissues from radiation and other auxiliary equipment, and after testing on larger animals clinical trials can get started. "Creating a fully-fledged system - is a matter of a year, maybe one and a half year" - Peter Shchedrovitsky, deputy director of the corporation Rosatom says. Sourses:


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