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Neutron Source for Boron Neutron Capture Therapy

#2569


Accelerator Based Neutron Source for Boron Neutron Capture Therapy

Tech Area / Field

  • PHY-PFA/Particles, Fields and Accelerator Physics/Physics
  • BIO-RAD/Radiobiology/Biotechnology
  • MED-RAD/Radiomedicine/Medicine

Status
8 Project completed

Registration date
29.07.2002

Completion date
21.09.2007

Senior Project Manager
Novozhilov V V

Leading Institute
Budker Institute of Nuclear Physics, Russia, Novosibirsk reg., Akademgorodok

Supporting institutes

  • VNIITF, Russia, Chelyabinsk reg., Snezhinsk\nMedical Radiological Scientific Center, Russia, Kaluga reg., Obninsk\nFEI (IPPE), Russia, Kaluga reg., Obninsk

Collaborators

  • Forschungszentrum Karlsruhe Technik und Umwelt / Institut für Hochleistungsimpuls und Mikrowellentechnik, Germany, Karlsruhe

Project summary

The goal of the project is construction of demonstrational compact accelerator based neutron source for neutron capture therapy in an oncologic hospital. An innovative accelerator concept permits transport of very high current beam with exceptionally high reliability in a compact, low cost system. Innovative mode of neutron generation allows to obtain kinematically collimated beam of epithermal neutrons without using complex system of moderators, collimators and reflectors.

The concept of neutron capture therapy (NCT) is simple and elegant. A tumor-seeking compound containing stable isotope 10B is introduced into blood and given time to be accumulated in the tumor. The tumor is then irradiated with epithermal neutrons, which are captured by 10B isotope. Capturing neutrons causes the boron nuclei to break apart, resulting in the emission of a-radiation and recoiling 7Li nuclei. Both a-particles and lithium are high in energy but short in range and high relative biological effectiveness, which means that they destroy the malignant cells in which boron is embedded without hurting the adjacent healthy cells. Therefore, boron neutron capture therapy (BNCT) will make it possible to destroy selectively tumor cells at higher 10B concentration than in normal ones.

At present, the boron neutron capture therapy is very attractive method for curing malignant tumors, especially therapy for glioblastoma multiforme and melanoma, that are resistant to other methods of treatment.

Progress in BNCT at clinical trials at reactors and prospects of the technique led to intensive discussion of development and construction of neutron source based on compact and inexpensive accelerator available for every oncologic hospital. A new approach in accelerator design is needed to produce the required epithermal neutron spectrum and flux in a reliable compact system and at an acceptable overall cost. The approach we propose is based upon tandem electrostatic accelerator with vacuum insulation and near threshold neutron generation. A high current negative hydrogen ion beam is injected into vacuum insulation tandem. After charge-exchange of negative hydrogen ion to proton inside charge-exchange tube in the center of high voltage electrode, a proton beam is formed at the outlet of the tandem, which is accelerated to double voltage of high voltage electrode. Neutron generation is proposed to be carried out by dropping proton beam onto lithium target using 7Li(p,n)7Be threshold reaction. This innovative accelerator which is named vacuum insulation tandem accelerator (VITA) will have two modes of operation. The most efficient innovative operating mode of the facility is at proton energy of 1.889-1.9 MeV that is 10-20 keV higher than the threshold of the 7Li(p,n)7Be reaction. In this mode, neutron beam is provided kinematically collimated in a cone with opening angle of ~25° and average energy of 30 keV, directly applicable for boron neutron capture therapy. The second mode at proton energy of 2.5 MeV produces a more complex neutron spectrum that extends to 790 keV that may be used for neutron capture therapy after moderation. Creation of accelerator with proton beam intensity of tens milliamperes will decrease exposure time for necessary therapeutic dose to tens minutes.

Development of conception project of accelerator based neutron source for the neutron-capture and fast neutron therapy at hospital was supported by International Sciences and Technology Center (Project #1484) on 1999. During the project realization period (May 1, 2000 - April 30, 2002) experimental modelling and investigation of the most important elements of the whole facility we carried out. As a result of investigations according to the ISTC project #1484, conceptual project of accelerator based neutron source was prepared available for BNCT and fast neutron therapy in an oncology hospital.

Natural continuation of work on compact neutron source for NCT is construction of demo neutron source in a special radiation shielding hall basing on tandem-accelerator developed according to ISTC project #1484.

The institutions and direct executors of the project have the unique qualification, investigation and design works were carried out on all the components of the proposed neutron source, and rich experience was stored and schools were formed in the number of cases. At BINP original electrostatic vacuum insulation tandem accelerator was developed which used sectionalized rectifier from electron accelerator of ELV type as a powerful source of high voltage. A surface plasma technique for negative ion generation was proposed and realized in BINP, basic modifications of surface plasma sources operating at most of the large proton accelerators all over the world were developed. Cylindrical lenses with solid or liquid lithium and liquid metal targets (lithium, gallium, plumbum) applied in high energy physics for secondary particles beam generation were produced. Great experience has been accumulated in experimental and theoretical investigations of the spatial-energy distribution of neutrons produced in 7Li(p,n)7Be reaction and neutron calculations of spatial distribution of the absorbed doze at IPPE. New fundamental knowledge on the nature of biological effect of neutrons was obtained at IPPE in collaboration with MRRC, physical and dozimetrical characteristics of neutron beams of reactor and accelerators were studied and treatment by neutron radiation therapy was carried out. Rich experience of many years of work with neutrons, with lithium hydride, radioactive materials, of simulations of charged particle beam transporting was accumulated at VNIITF.

Expected Results. In course of implementation of the project:

– stationary source of hydrogen negative ions will be developed, and 10 mA beam will be obtained;


– stable operation of tandem accelerator will be provided, and 2 MeV proton beam will be obtained;
– neutron producing target will be developed, and neutron generation will be realized;
– preparation will be made for theraupetic use of neutron beam;
– work of future improvement of neutron source will be carried out.

As a result, successful realization of the project will demonstrate possibility of compact and low cost solution for BNCT.

It should be emphasized that this work serves one of the most important purposes that is people’s health. There is no material estimation for the incipient possibility to cure people exposed to dreadful disease.


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