Evgeny Samsonov

C235-V3 cyclotron for a proton therapy center to be installed in the hospital complex of radiation medicine (Dimitrovgrad)

Proton therapy is an effective method of treating oncologic diseases. In Russia, construction of several centers for proton and ion therapy is slated for the years to come. A proton therapy center in Dimitrovgrad will be the first. The Joint Institute for Nuclear Research (Russia) in collaboration with Ion Beam Application (IBA) (Belgium) has designed an C235-V3 medical proton cyclotron for this center. It outperforms previous versions of commercial IBA cyclotrons, which have already been installed in 11 oncologic hospital centers in different countries. Experimental and calculation data for the beam dynamics in the C235-V3 medical cyclotron are presented. Reasons for beam losses during acceleration are considered, the influence of the magnetic field radial component in the midplane of the accelerator and main resonances is studied, and a beam extraction system is designed. In 2011–2012 in Dubna, the cyclotron was mounted, its magnetic field was properly configured, acceleration conditions were optimized, and beam extraction tests were carried out after which it was supplied to Dimitrovgrad. In the C235-V3 cyclotron, an acceleration efficiency of 72% and an extraction efficiency of 62% have been achieved without diaphragming to form a vertical profile of the beam.

Beam dynamics in a C253-V3 cyclotron for proton therapy

In recent years, oncologic diseases have become a severe issue in developed countries. Proton therapy is viewed as one of the most efficient methods of treating oncologic diseases. The results of computing the beam dynamics in a C235 medical cyclotron intended for proton therapy are presented. The cyclotron was modified by teams of researchers at the Joint Institute for Nuclear Research and Ion Beam Application (IBA Group, Belgium). Possible reasons for losses in the beam under acceleration are considered, and the influence of the magnetic field radial component in the median plane of the accelerator is studied. The results of analysis and upgrading of the beam extraction system are presented. Based on analytical data, the design of the commercial C235 cyclotron is considerably modified. A new version of the C235-V3 cyclotron will be placed in commission at the Dimitrovgrad center of radiation medicine.

Development of radiation medicine at DLNP, JINR

The Dzhelepov Laboratory of Nuclear Problems’ activity is aimed at developing three directions in radiation medicine: 3D conformal proton therapy, accelerator techniques for proton and carbon treatment of tumors, and new types of detector systems for spectrometric computed tomography (CT) and positron emission tomography (PET). JINR and IBA have developed and constructed the medical proton cyclotron C235-V3. At present, all basic cyclotron systems have been built. We plan to assemble this cyclotron at JINR in 2011 and perform tests with the extracted proton beam in 2012. A superconducting isochronous cyclotron C400 has been designed by the IBA-JINR collaboration. This cyclotron will be used for radiotherapy with proton, helium and carbon ions. The 12C6+ and 4He2+ ions will be accelerated to an energy of 400 MeV/amu, the protons will be extracted at the energy 265 MeV. The construction of the C400 cyclotron was started in 2010 within the framework of the Archarde project (France). Development of spectrometric CT tomographs may allow one to determine the chemical composition of a substance together with the density, measured using traditional CT. This may advance modern diagnostic methods significantly. JINR develops fundamentally new pixel detector systems for spectrometric CT. The time-of-flight (TOF) system installed in the positron emission tomograph (PET) permits essential reduction in the detector noise from occasional events of different positron annihilations. The micropixel avalanche photodiodes (MAPDs) developed at JINR allow a factor of 1.5 reduction in the resolution time for the PET TOF system and suppression of the noise level as compared to commercial PET. The development of a combined PET/MRI is of considerable medical interest, but it cannot be made with the existing PET tomographs based on detectors of compact photomultipliers due to strong alternating magnetic field of MRI. Change-over to detectors of micropixel avalanche photodiodes permits making a combined PET/MRI.

The construction of the inner ion source for SC200 compact superconducting cyclotron

The SC200 compact superconducting cyclotron is supposed to contribute on the proton therapy under the collaboration of the Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP) and the Joint Institute for Nuclear Research (JINR). The energy of cyclotron is 200 MeV with the maximum proton beam current of ∼400 nA from the cyclotron outlet. The hot cathode Penning Ionization Gauge (PIG) type proton source will be used in the cyclotron. The purpose of the article is to introduce the inner ion source from the design, simulation and dedicated test. Through the analysis and bench experiment results, the ion source shows a good performance which can provide enough protons to reach the cyclotron beam current. The lifetime of filament can reach more than 50 hours and the source operates at least 1h continuously. A layer-to-layer intensity modulation of the scanned beam is realized with the filament current and the arc voltage that need to vary the extracted beam current between maximum and zero. For the ...

The trajectory simulation and optimization of ion source chimney for SC200 cyclotron

SC200 is an isochronous cyclotron which generate 200 MeV, 500 nA proton for particle therapy. As an important component of the cyclotron, the ion source chimney needs to be tested and optimized. Th...

Hadron Therapy Research and Applications at JINR

JINR has the unique experience in cancer treatment with proton beam during about 50 years. In 2005 the collaboration with IBA (Belgium) was established. During these years, the technical design of the first carbon superconducting cyclotron C400 was successfully created, the construction of serial proton cyclotron C235 was significantly improved and the fist modernized cyclotron C235 was assembled, debugged and put in the test operation in Dubna in 2011. This C235 will be used soon in the first Russian medical center with proton therapy in Dimitrovgrad. In 2015 the joint project with ASIPP (Hefei, China) on design and construction of superconducting proton cyclotron SC202 was started. Two copies of SC202 shall be produced, according to the Collaboration Agreement between JINR and ASIPP. One will be used for proton therapy in Hefei and the second one will replace the Phasotron to continue the proton therapy at JINR. PROTON THERAPY IN JINR The history of proton therapy in JINR began 50 years ago: • 1967 – the beginning of the research on proton therapy; • 1968 –1974 – first 84 patients treated with protons; • 1975 –1986 – upgrading of accelerator and construction of a multi -room Medico -Technical Complex (MTC); • 1987 -1996 – treating of 40 patients with protons; • 1999– inauguration of a radiological department of the Dubna hospital; • Since 2000 regular treating of patients with tumors seated in the head, neck and thorax. The modern technique of conformal three-dimensional proton therapy was realized firstly in the JINR Medicaltechnical accelerator complex which includes the Phasotron, the beam delivery systems and medical cabins. Now JINR is the leading research centers of proton therapy in Russia. About 100 patients take a course of fractionated treatment in Dubna every year. During last 14 years from the startup of the Dubna radiological department more than 1000 patients were treated with proton beams [1]. The initial operation of the accelerator took place in 1949. In 1979-1984, the synchrocyclotron was converted into azimuthally varying field Phasotron. Now it is heavily depreciated and out of date, so it is important to replace it with the modern accelerator. JINR (DUBNA) –IBA (BELGIUM) COLLABORATION Superconducting C400 Cyclotron IBA, the world’s industrial leader in equipment of the proton therapy centers, in collaboration with JINR has designed the first superconducting carbon C400 cyclotron [2]. Most of the operating parameters (particle energy, magnetic field, RF frequency) of the C400 cyclotron are fixed. Small main field and RF frequency variation are necessary for the switching from one element to another. It is relatively small (6.6 m in diameter) and cost effective. It offers very good beam intensity control for ultra-fast pencil beam scanning (PBS). But it requires an energy selection system (ESS) in order to vary the beam energy. The efficiency of the ESS for carbon is better than for protons due to lower scattering and straggling of carbon ions in the degrader. The key parameters of the 400MeV/u superconducting cyclotron are listed in Table 1. The view of the cyclotron is presented in Fig.1. Table 1. Main Parameters of the C400 Cyclotron

Measurement of the magnetic-field parameters of the NICA Booster dipole magnet

Serial assembly and tests of dipole and quadrupole magnets of the NICA Booster have started at the Laboratory of High Energy Physics of the Joint Institute for Nuclear Research (JINR). The accelerator is fitted with Nuclotron-type magnets with a superconducting winding and an iron yoke for shaping the needed magnetic field. The design of magnets for NICA was optimized (based on the experience gained in constructing and operating the JINR Nuclotron) for the production of magnetic fields of the required configuration in terms of the beam dynamics in the accelerator and the collider. Measurements of parameters of the field of each magnet are expected to be performed in the process of assembly and testing of each module of the magnet-cryostat system of the NICA Booster and Collider. The results of magnetic measurements for the NICA Booster dipole magnet are presented.

Effect of imperfections of the radial component of a magnetic field on beam dynamics in medical cyclotron C235-V3

This paper presents numerical simulations and experimental results related to the effect of imperfections of the radial component of a magnetic field on the beam dynamics in the medical cyclotron C235-V3 of the Dimitrovgrad Proton Therapy Center. These imperfections in the region of the minimal axial betatron frequency lead to a transformation of coherent motion of the center of gravity of the beam to the incoherent motion of separate particles. The radial component increases the axial size of the beam by a factor of 2 at a radius of 20 cm, which produces additional losses of protons. To reduce undesirable actions of the radial component on the axial motion, the magnetic system in the central region has been optimized using two procedures: the positioning of shim correctors on sectors and selecting a special asymmetric arrangement of the upper and lower central plugs. This led to a twofold reduction in the axial size of the beam and a decrease in proton losses. Eventually, the beam transmission in C235-V3 has been increased to 72% without a limiting aperture diaphragm, which is commonly used in cyclotrons of this type. This makes it possible to reduce the irradiation dose of machine elements and increase the beam current at a deflector entrance of the cyclotron C235-V3 by a factor of 1.5 when compared to a serial C235 cyclotron.

Correction of vertical displacement of extracted beam during commissioning tests of the DC-110 cyclotron

The specialized DC-110 heavy ion cyclotron has been developed and created at the Laboratory of Nuclear Reactions of the Joint Institute for Nuclear Research for the BETA research and production complex in Dubna (Russia), which allows producing intense accelerated Ar, Kr, and Xe ion beams with a fixed energy of 2.5 MeV/nucleon. Commissioning works on the cyclotron complex, during which the design parameters were obtained, were carried out at the end of 2012. During commissioning of the accelerator, vertical displacement of the beam was found at the final acceleration radii and during its extraction. It is shown that the main cause of this displacement was the occurrence of a radial component of the magnetic field in the median plane of the magnet caused by asymmetry of the magnetic circuit. Vertical beam displacement was corrected by creating asymmetry of the current in the main electromagnet winding of the DC-110 cyclotron.

Numerical simulation of ions acceleration and extraction in cyclotron DC-110

In Flerov’s Laboratory of Nuclear Reactions of JINR in the framework of project “Beta” a cyclotron complex for a wide range of applied research in nanotechnology (track membranes, surface modification, etc.) is created. The complex includes a dedicated heavy-ion cyclotron DC-110, which yields intense beams of accelerated ions Ar, Kr and Xe with a fixed energy of 2.5 MeV/A. The cyclotron is equipped with external injection on the base of ECR ion source, a spiral inflector and the system of ions extraction consisting of an electrostatic deflector and a passive magnetic channel. The results of calculations of the beam dynamics in measured magnetic field from the exit of spiral inflector to correcting magnet located outside the accelerator vacuum chamber are presented. It is shown that the design parameters of ion beams at the entrance of correcting magnet will be obtained using false channel, which is a copy of the passive channel, located on the opposite side of the magnetic system. Extraction efficiency of ions will reach 75%.