Neutron Therapy Planning System
Development of a Treatment Planning System for the Snezhinsk Neutron Therapy Center
Tech Area / Field
- INF-SOF/Software/Information and Communications
- MED-DID/Diagnostics & Devices/Medicine
8 Project completed
Senior Project Manager
Novozhilov V V
State Unitary Enterprise STRELA, Russia, Chelyabinsk reg., Snezhinsk
- Lawrence Livermore National Laboratory, USA, CA, Livermore
Project summaryUp-to-date progress in clinical radiobiology and radiation oncology and development of high-tech medical equipment have significantly increased the quality and effectiveness of beam therapy, though have not yet resolved all problems pertaining to the treatment of malignant tumors resistant to photon radiation. In such cases the use of neutron therapy using fast neutron beams seems to be rather promising.
Since July 1999 Neutron Therapy Center has been operating at RFNC-VNIITF, Snezhinsk. The Center exploits neutron generator NG-12I /1/ producing 14-MeV neutrons with the flux of 1012 n/s. Medical support to the Center is provided by the experts of Cancer Detection and Treatment Center in Chelyabinsk, where they perform primary examination of the patients, diagnostic studies, collection of topological and metrical information about the patients and treatment planning. The photon therapy phase of the treatment is also provided at Chelyabinsk Center and after that the patients are transported to Snezhinsk for the neutron therapy stage at the Neutron Therapy Center. Analysis of the patients already treated shows that the combined photon-neutron therapy is 1.5 times more effective than mere photon therapy. /2/.
In radiation oncology an urgent problem is beam therapy quality assurance /3,4/ since deviation of focal dose from the planned one for more than 5% causes unfavorable clinical consequences /5/. An important role in solving this problem is played by dosimetric planning /6/ - determining such irradiation conditions, under which the focal dose will correspond to the planned one and the dose absorbed by healthy tissue will be within the tolerance dose. Dosimetric planning is based on the simulation of the absorbed dose distribution over the patient’s body under the given irradiation conditions /7/. A modern tool for the dosimetric planning is an interactive treatment planning system, a code for absorbed dose calculation being its kernel.
The objective of the proposed project is to develop a treatment planning system for the Neutron Therapy Center in Snezhinsk. Such system, if used in the medical practice, would improve the dosimetric planning of the treatment and would facilitate neutron therapy quality assurance. This shows a significant social value of the proposed project.
The term of the planning system development is of importance for the Neutron Therapy Center, which is already in operation. Lawrence Livermore National Laboratory (LLNL) and Idaho National Engineering and Environmental Laboratory (INEEL), foreign collaborators of the Project, have proposed that the development is speeded up by using the existing neutron therapy planning system SERA /8,9/ developed at INEEL. The INEEL has been involved in neutron radiotherapy research and in the development of advanced neutron radiotherapy planning software for almost 15 years. The result of this developmental effort led to the introduction of the completely new SERA (Simulation Environment for Radiotherapy Applications) treatment planning software in 1998.
SERA system provides a qualitatively new level of dosimetric planning due to the accurate simulation of the whole process of irradiation. To obtain topological and metrical information about the patient, multi-layered scanning of the tumor area is done at CT and a novel method is used to reconstruct patient geometry from these medical images. This information and a detailed description of the radiation source and the beam modifying system are the input data for the Monte Carlo calculation of the absorbed dose distribution. Calculation correctness is ensured by the use of the recent nuclear data and detailed simulation of the whole process of radiation propagation in the source-patient system. Though Monte Carlo calculations are time-consuming, the original algorithms ensure practical effectiveness of calculations.
In the course of Project implementation the following basic results are expected:
· The Project participant will study and master the up-to-date neutron therapy planning system SERA which will be used as a basis for the creation of the treatment planning system for the Neutron Therapy Center in Snezhinsk.
· Experimental data will be obtained characterizing the neutron beam at the outlet of neutron facility NG-12I for a number of typical collimators. Based on these experimental and calculated data, a model for SERA code will be developed to describe the source of neutron facility NG-12I.
· In compliance with the source model the NG-12I neutron facility will be modeled in the data format of SERA code. To check the accuracy of irradiation simulation, measurements will be taken of the absorbed dose, beam pergence and neutron spectrum in tissue-equivalent phantoms for a number of NG-12I typical collimators.
· Treatment planning system SERA will be adapted for the needs of Snezhinsk Neutron Therapy Center.
The success of the project will be based on the high expertise of RFNC-VNIITF employees in development of Monte Carlo simulation codes for transport of particles. A general-purpose code PRIZMA /10-14/ has been evolving for 30 years. It calculates the linear problems of combined transport of neutrons, photons, electrons, positrons and heavy charged particles. PRIZMA code was used to select a biological shielding for the neutron generator and facilitate measurements of the neutron field of the generator. Experts from the laboratory “Development and maintenance of the visualization systems” will also contribute to the efforts under the Project. The every-day task of the laboratory’s staff is to develop user-friendly interfaces and different structures of data representation /15,16/. Expertise of the Experimental Division employees, the measuring equipment and dosimetric techniques they have /17,18/ will facilitate the project implementation in the part of experimental activities at the neutron generator and verification of numerical simulation. Activities under the project will be done in close cooperation with the experts of Cancer Detection and Treatment Center in Chelyabinsk.
The Project will provide an opportunity to the scientists working for RFNC-VNIITF, a leading Russian nuclear weapons development center, to participate in the peaceful medical activities that are of great social value. Activities in this area will expand and deepen cooperation of the Russian scientists with their foreign colleagues.
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8. D.W. Nigg, C.A. Wemple, D.E. Wessol, F.J. Wheeler, et. Al., “SERA-An Advanced Treatment Planning System for Neutron Therapy and BNCT”, Trans. ANS, Bio. Med. Div. 80:66-68 (1999).
9. D.E. Wessol, C.A. Wemple, F.J. Wheeler, M.T. Cohen, M.B. Rossmeier, J. Cogliati, “SERA: Simulation Environment for Radiotherapy Applications Users Manual Version 1B0”, http://www.cs.montana.edu/~bnst, INEEL External Report, October, 1999.
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14. Kandiev Ya.Z., Malyshkin G.N. Modeling by Value Implemented in PRIZMA Code. V Joint Russian-American Computational Mathematics Conference // Sandia Report. SAN98-1591, 1998, P. 149-158.
15. V.M. Kryukov, D.V. Mogilenskikh, V.V. Fedorov. 2D and 3D visualization of the results of numerical simulation of complex physical systems. Proceedings of the Conference “Graphicon’95”. St.-Petersburg, July 3-7, 1995, V.2. and Proceedings of Joint Computational Mathematics Conference May 20-25, 1996, Snezhinsk (in Russian).
16. D. V. Mogilenskikh, I.V. Pavlov, V.V. Fedorov, S.N. Melnikova, E.E. Sapozhnikova. Structure and functions of visualization system for analysis of scalar and vector fields specified on 2D regular mesh. Preprint RFNC-VNIITF #172, Snezhinsk, 2000. http:www.sci.urc.ac.ru/news.
17. Magda E.P., Litvin V.I., Kandiev Ya.Z., et al. “Dosimetric parameters of the beam generated by NG-12 facility” Collection of papers “Neutron Application in Oncology”, Tomsk: NTP, 1998, p. 28 (in Russian).
18. Litvin V.I., Lukin A.V., Sokolov Yu.A., et al. “Critical benchmark experiments and reaction number measurements in cylindrical systems of uranium, plutonium and polyethylene at FKBN test-bed. Preprint #159, RFNC-VNIITF, 1999 (in Russian).