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量研関西研では,レーザー駆動イオン加速機構によって生じる炭素ビームの横方向エミッタンスを明らかにすることに取り組んでいる。同時加速される陽子ビームから炭素ビームを弁別することが困難であるために，炭素ビームの横方向エミッタンスが評価された例はない。現在, 四重極磁石による核種の磁場弁別とダブルスリット法とを組み合わせた炭素ビーム横方向エミッタンス診断系の開発を進めている。 本発表では, 数理的な考えを診断装置に組み込むことによる, 観測誤差の低減に関して報告する予定である。, 第69回応用物理学会春季学術講演会

Heavy ion radiotherapy with the Heavy-Ion Medical Accelerator in Chiba (HIMAC) has been carried out more than 13000 patients since 1994. In 2010, a new particle therapy research facility connected to HIMAC was built, and we started heavy-ion radiotherapy using a 3D scanning irradiation system in 2011 and using a superconducting rotating gantry in 2017 at the new facility. In 2016, we began a project of "quantum scalpel", a next-generation heavy-ion radiotherapy machine that applies a compact superconducting synchrotron and rotating gantry currently under development. This paper outlines R&Ds for a new project and current facility as well as the present status of HIMAC.

Carbon-ion radiotherapy using the Heavy-Ion Medical Accelerator in Chiba (HIMAC) at the National Institute of Radiological Sciences (NIRS) has been conducted on more than 12,000 patients since 1994. We started the heavy-ion radiotherapy with a 3D scanning irradiation system in 2011 and using a superconducting rotating gantry in 2017, at a new treatment research facility in NIRS. We have continued some R&Ds on HIMAC to enhance the treatment quality and to improve the treatment results. From 2016, we have started developments of a compact superconducting rotating gantry and synchrotron to be applied for a newly started project of a “quantum scalpel” that is a next generation of the heavy-ion radiotherapy machine. This paper outlines those R&Ds as well as the present status of HIMAC facility.

We carried out repeated excitation experiments of a test magnet for accelerator applications of RE-123 coated conductors in order to study its tolerance against ac loss and the stability as well as the reproducibility of the generated magnetic field. The magnet consists of a pair of 4-stacked racetrack coils with an iron return yoke in the low temperature region. It can generate 2.4 T of dipole magnetic field at its room temperature beam duct with its rated current of 200 A, and the maximum magnetic field to which the coated conductor is exposed is about 4 T. At first, the magnet was excited repeatedly with a saw-tooth waveform to examine the tolerance against ac loss: the magnetic field was ramped up to 4 T at the conductor in 120 s and down to 0 T in 120 s. We also carried out numerical electromagnetic field analyses to estimate the ac loss in the magnet. Next, we examined the influence of shielding currents on the field stability and reproducibility at the steps during ramping down, where the current was held constant. This simulated the excitation pattern of magnets for carbon gantries.

Purpose The purpose is to verify experimentally whether application of magnetic fields longitudinal and perpendicular to a proton beam alters the biological effectiveness of the radiation. Methods and Materials Proton beams with linear energy transfer of 1.1 and 3.3 keV/μm irradiated human cancer and normal cells under a longitudinal (perpendicular) magnetic field of BL (BP) = 0, 0.3, or 0.6 T. Cell survival curves were constructed to evaluate the effects of the magnetic fields on the biological effectiveness. The ratio of dose that would result in a survival fraction of 10% without the magnetic field Dwo to the dose with the magnetic field Dw, R10 = Dwo/Dw, was determined for each cell line and magnetic field. Results For cancer cells exposed to the 1.1- (3.3-) keV/μm proton beams, R10s were increased to 1.10 ± 0.07 (1.11 ± 0.07) and 1.11 ± 0.07 (1.12 ± 0.07) by the longitudinal magnetic fields of BL = 0.3 and 0.6 T, respectively. For normal cells, R10s were increased to 1.13 ± 0.06 (1.17 ± 0.06) and 1.17 ± 0.06 (1.30 ± 0.06) by the BLs. In contrast, R10s were not changed significantly from 1 by the perpendicular magnetic fields of BP = 0.3 and 0.6 T for both cancer and normal cells exposed to 1.1- and 3.3-keV/μm proton beams. Conclusions The biological effectiveness of proton beams was significantly enhanced by longitudinal magnetic fields of BL = 0.3 and 0.6 T, whereas the biological effectiveness was not altered by perpendicular magnetic fields of the same strengths. This enhancement effect should be taken into account in magnetic resonance imaging guided proton therapy with a longitudinal magnetic field.

Background and Purpose The purpose is to verify experimentally whether application of magnetic fields longitudinal and perpendicular to a proton beam alters the biological effectiveness of the radiation. Methods and Materials Proton beams with linear energy transfer (LET) of 1.1 and 3.3 keV/μm were irradiated onto human cancer and normal cells under the longitudinal (perpendicular) magnetic field of BL (BP) = 0, 0.3, or 0.6 T. Cell survival curves were constructed to evaluate the effects of the magnetic fields on the biological effectiveness. The ratio of dose that would result in a survival fraction of 10% without the magnetic field Dwo to the dose with the magnetic field Dw, R10 = Dwo / Dw, was determined for each cell line and magnetic field. Results For cancer cells exposed to the 1.1- (3.3-) keV/μm proton beams, R10s were increased to 1.10±0.07 (1.11±0.07) and 1.11±0.07 (1.12±0.07) by the longitudinal magnetic fields of BL = 0.3 and 0.6 T, respectively. For normal cells, R10s were increased to 1.13±0.06 (1.17±0.06) and 1.17±0.06 (1.30±0.06) by the BLs. In contrast, R10s were not changed significantly from 1 by the perpendicular magnetic fields of BP = 0.3 and 0.6 T for both cancer and normal cells exposed to 1.1- and 3.3-keV/μm proton beams. Conclusions The biological effectiveness of proton beams was significantly enhanced by the longitudinal magnetic fields of BL = 0.3 and 0.6 T, while the biological effectiveness was not altered by the perpendicular magnetic fields of the same strengths. This enhancement effect should be taken into account in MRI guided proton therapy with a longitudinal magnetic field.

Previous studies have revealed application of a magnetic field longitudinal to a carbon-ion beam enhances its biological effectiveness. This communication investigated how timing of the magnetic field application with respect to beam irradiation influenced this effect. Human cancer cells were exposed to carbon-ion beams with linear energy transfer (LET) of 12 and 50 keV/μm. The longitudinal magnetic field of 0.3 T was applied to the cells just before, during, or right after the beam irradiation. The effects of the timing on the biological effectiveness were evaluated by cell survival. The biological effectiveness increased only if the magnetic field was applied during beam irradiation for both LET beams.

A study of multiple-ion therapy with charged heavy-ion beams was performed to improve outcomes of refractory cancer treatments. We proposed the accelerator operation method for applying the multiple-ion therapy, to quickly switch the ion species and energies of the output beams. In this method, the irradiation ion species can be changed only by switching the selected ion source and the injector parameters, and the output beam energies can be varied without changing the magnetic operation patterns of the synchrotron. We verified the effectiveness of our approach by conducting experiments at the Heavy Ion Medical Accelerator in Chiba (HIMAC) and confirmed that the approach can provide the fast switching of both the ion species and the beam energies. The experimental results also demonstrated that our approach will greatly reduce the commissioning time and the routine adjustments for multiple-ion beams.

A project to develop a compact heavy ion therapy device has been initiated at the National Institutes for Quantum and Radiological Science and Technology . The therapy device uses a 430 MeV/u synchrotron with superconducting bending magnets as a main accelerator. In order to reach the required output of the heavy ion beam, the bending magnets have been designed to be operate d alternately from 0.3 T (for to 3.5 T maximum (for extraction) at the ramping rate of 0.6 T/s. The 3D electromagnetic design of the synchrotron bending magnet has been performed. The magnetic length is 1.49 m for 45 degree bending angle, and curvature radius is 1.89 m. The superconducting coil consists of a low loss NbTi wire with a 1 mm diameter , and t he maximum operating current is 265A. To suppress the magnetomotive force, t he cross sectional coil design adopt ed an elliptical shaped arrangement. The coil and iron yoke designs were optimized for the uniformity of the magnetic field in the required area In addition, a short straight model with a magnetic length of 400 mm w as fabricated for the feasibility demonstration. The results of the excitation test as well as the electromagnetic design will be reported., 27th International Conference on Magnet Technology

National Institute of Radiological Sciences (NIRS) promotes multiple ion therapies that form LET and dose distribution with ideal relative biological effectiveness in cancer treatment by irradiating several types of ions to the target. We are developing a compact ECR ion source of all permanent magnets that produces four ions (He2+, C4+, O3+, Ne7+) used in multiple ion therapy. We produced four ions with NIRS-HEC in a fixed magnetic field. As a result, it was obtained ion beam with sufficient intensity for multi-ion treatment. At present, there is a request of high energy beams for biological/physical experiments in addition to therapeutic use in heavy ion radiotherapy facilities. Also, considering cost reduction of the injector, it is necessary to produce ions other than carbon in the ion source and to produce an ion beam having a higher charge than that during treatment supply. Therefore, it is confirmed whether the new ion source can be applied to applications other than treatment supply. We performed C4+ and C5+ production tests in a fixed magnetic field with NIRS-HEC. As a result of using two gases and afterglow tuning, it was obtained that sufficient ion beam of 800 μA for C4+ and 500 μA for C5+.

The National Institute of Radiological Sciences in Japan started clinical studies of carbon-ion radiotherapy (CIRT) in 1994. Due to the high linear energy transfer (LET) of highly charged particles, carbon-ion beams show high relative biological effectiveness in cell killing, especially at the Bragg peak of dose near the beam range, which is controlled to conform to a tumor. Recent technological developments for CIRT include fast pencil-beam scanning, fluoroscopic respiratory motion management, advanced beam modeling for treatment planning, and a superconducting rotating gantry, which have contributed to accuracy, precision, and conformation of dose, operational efficiency, and patient comfort. With technological maturity, CIRT facilities are rapidly increasing in Asia and Europe. Ongoing developments include extension to multiple ion species and facility downsizing to raise the quality and availability of ion-beam therapy in medical care.

A cryocooler-cooled high-temperature superconducting magnet was constructed, and it was tested on the beam line of the heavy ion medial accelerator in Chiba (HIMAC). The magnet consists of a pair of four-stacked racetrack coils wound with RE-123 coated conductor that are plated with 41- μ m copper for protection. The magnet has a room temperature beam duct, at which 2.4 T of magnetic field is generated, whereas the maximum magnetic field to which coated conductors are exposed is approximately 4 T. The magnetic field in the beam duct was measured and calculated to examine its stability, which might have been affected by shielding currents in the coated conductors. On the beam line of the HIMAC, at first, the beam guiding by the magnet was demonstrated. The measured beam-guiding characteristics were compared with the beam tracking calculations. Next, a carbon ion beam was injected intentionally into the RE-123 coils of the magnet to simulate the incidents of uncontrolled beam injection into accelerator magnets. Prior to this test, the possible heat deposition to the coil by the beam injection was calculated, and the feasibility of quench protection using a dump resistor was studied through quench experiments using short pieces of the RE-123 coated conductors.

An R&D project funded by the Japan Science and Technology Agency under its S-Innovation Program is currently in progress. The purpose of this project is to develop fundamental technologies for accelerator magnets with REBCO coils. In the first step of this project, winding technology for fabricating REBCO coils required for HTS accelerator magnets was developed. At the last stage of this project, there are plans to fabricate cryocooler-cooled REBCO magnets and evaluate the beam guiding characteristics and stability against beam injection to the magnets at the beam line of Heavy Ion Medical Accelerator in Chiba (HIMAC). This paper describes the design of an HTS magnet fabricated for this evaluation and presents fabrication results of this magnet. The magnet had a room-temperature beam duct with dimensions 264× 40 mm for beam guiding. The magnet consisted of a pair of racetrack coil stacks each containing four coils, and a cold iron was adopted to increase the magnetic field strength. It could generate a dipole field of 2.4 T at the beam duct by 200 A excitation. Furthermore, beam windows were placed on the side of the cryostat for beam injection tests, allowing the beam to irradiate the REBCO coil directly.

Purpose: Our previous study revealed that the application of a magnetic field longitudinal to a carbon-ion beam of 0.1 ≤ B//≤ 0.6 T enhances the biological effectiveness of the radiation. T...

Purpose: A magnetic field longitudinal to an ion beam will potentially affect the biological effectiveness of the radiation. The purpose of this study is to experimentally verify the significance o...

2020年度量子医科学研究所 重粒子線がん治療装置等共同利用研究報告書

量研・ 関西研では 、超電導シンクロトロンとレーザー駆動炭素インジェクターを組み合わせた重粒子線治療装置の量子メスの開発を進めている。この開発では、 TNSA 法 により、4MeV/ 核子の炭素を発生させ入射することを目標としているが、レーザー駆動加速イオンの特徴であるピコ秒領域の極短パルス大電流という炭素ビームが「ビーム輸送系を介して超伝導 シンクロトロン のアクセプタンスに入射できるのか」という点については十分な検討がされていない。そこで、ビーム診断系および輸送系コンポーネント（磁石、静電レンズ）通過時 に生じる磁場および電場（空間電荷効果以外の外力）による 非線形性の増大に関して計算できるように整備した。今回はそれらの 結果と、量子メス実験用プラットホームでペッパーポット式のエミッタンスモニタで求めた数十keV級低エネルギーのイオンビームのエミッタンス量の結果を比較検討したので報告する。, 日本物理学会第76回年次大会

Gradual increase in leakage current introduced by heavy ions irradiation was observed for silicon carbide metal-oxide-semiconductor (SiC MOS) capacitors under the negative bias voltage condition. In contrast, abrupt increase was observed for positive biased condition as previously observed for Si MOS devices. It was identified that the degradation sites introduced under negative bias have a rectifying I–V characteristic, which were too small to cause a clear shift of the C–V curve. It was inferred that the hetero junction formed in SiC MOS capacitors was the key structure for suppressing catastrophic failures mode observed in Si MOS structures., Nuclear & Space Radiation Effects Conference 2020( NSREC 2020)

A development project for hypo-fractionated multi-ion therapy has been initiated at the National Institute of Radiological Sciences in Japan. In the treatment, helium, carbon, oxygen, and neon ions will be used as primary beams with pencil beam scanning. A ripple filter (RiFi), consisting of a thin plastic or aluminum plate with a fine periodic ridge and groove structure, has been used to broaden the Bragg peak of heavy-ion beams in the beam direction. To sufficiently broaden the Bragg peak of helium-, carbon-, oxygen-, and neon-ion beams with suppressed lateral scattering and surface dose inhomogeneity, in this study, we tested a plate made of a lung substitute material, Gammex LN300, as the RiFi. The planar integrated dose distribution of a 183.5 MeV u−1 neon-ion beam was measured behind a 3 cm thick LN300 plate in water. The Bragg peak of the pristine beam was broadened following the normal distribution with the standard deviation σ value of 1.29 mm, while the range of the beam was reduced by 8.8 mm by the plate. To verify the LN300 performance as the RiFi in multi-ion therapy, we measured the pencil beam data of helium-, carbon-, oxygen- and neon-ion beams penetrating the 3 cm thick LN300 plate. The data were then modeled and used in a treatment planning system to achieve a uniform 10% survival of human undifferentiated carcinoma cells within a cuboid target by the beam for each of the different ion species. The measured survival fractions were reasonably reproduced by the planned ones for all the ion species. No surface dose inhomogeneity was observed for any ion species even when the plate was placed close to the phantom surface. The plate made of lung substitute material, Gammex LN300, is applicable as the RiFi in multi-ion therapy with helium-, carbon-, oxygen- and neon-ion beams.

The multi-ion radiotherapy with dose distribution and Liner Energy Transfer optimization is being studied at QST. Helium, carbon, oxygen and neon ions are considered as ion species for multi-ion therapy. A basic experiment using these ion beams has been carried out at the HIMAC. For heavy-ion radiotherapy facility, it is desirable to operate with only one ECR ion source with permanent magnets from the viewpoint of cost and maintenance. We considered the operating method with only one ion source for multi-ion radiotherapy. Ionization gases were helium, methane, oxygen, and neon to produce He2+, C4+, O6+ and Ne7+ ions. Requirement values of beam current were 940 μA correspond to He2+, 290 μA to C4+, 330 μA to O6+, and 245 μA to Ne7+, respectively. This value was obtained from the number of particles required for the cancer treatment and the transmission efficiency of the accelerator in the HIMAC. We performed some beam tests for design of a new compact ion source with the existing 18 GHz ECR ion source (NIRS-HEC). From the results of the beam tests, we estimate the mirror magnetic field of NIRS-HEC by using POISSON/SUPERFISH code. Then, the structure of the permanent magnets for new ECR ion source is determined so that they reproduce the values of the upstream mirror peak (Binj), B minimum (Bmin) and the downstream mirror peak (Bext) at the NIRS-HEC. The magnetic field of Binj, Bmin and Bext at NIRS-HEC were 1.14 T, 0.475 T and 0.9 T, respectively.

High-energy carbon-ion radiotherapy is being carried out at Heavy Ion Medical Accelerator in Chiba (HIMAC). Over 12000 cancer patients have been treated with carbon beams having energies of between 56-430 MeV/u since 1994. There are two injectors in the HIMAC for medical and experimental use. First injector consists of two ECR ion sources and one PIG ion source, the RFQ linac and the DTL. Usually, this injector suppling the carbon ion for cancer therapy and various ion such as H, He, Fe, Xe are accelerated for biological and physical experiment. The 10 GHz NIRS-ECR ion source produce the carbon ion for cancer therapy. The 18 GHz NIRS-HEC ion source produce He to Xe ions for experimental use. Second injector consists of the compact ECR ion source with all permanent magnet, the RFQ linac and the APF IH-DTL. This injector supplies the carbon ion for experimental use. Additionally, we tried production of the Indium and the Tin ions by using the In(C5H5) and the Sn(i-C3H7)4 at the NIRS-HEC. Beam current of the 115In20+ and 120Sn18+ were 90 and 15 microA, respectively., 24th International Workshop on ECR Ion Sources

The National Institute of Radiological Sciences has investigated multiple-ion therapy using energetic beams of helium, carbon, oxygen, and neon ions, to improve treatment outcomes of refractory cancer. For this therapy, it is necessary to ensure the helium-ion beam purity to avoid irradiation by unwanted ions. Here, we develop a measurement method for monitoring beam purity. This method can measure the charge number of the ions in a high-purity beam using an ionization chamber and Faraday cup. In addition, it can be used to detect the contamination of the clinical helium-ion beam. We perform beam experiments to evaluate our beam-purity monitoring method and predict that our method is capable of detecting contamination below 1%.

形態: カラー図版あり, Physical characteristics: Original contains color illustrations, Accepted: 2018-03-12, 資料番号: PA1810051000

Radiotherapy using high-energy carbon beams from the Heavy Ion Medical Accelerator in Chiba has been carried out at the National Institute of Radiological Sciences (NIRS) since June 1994, and more than 10 000 patients have been treated to date. With the prospective clinical results for the first ten years, we designed a compact accelerator facility for carbon-ion radiotherapy (CIRT), and performed related Research and Development (RD two of them have both horizontal and vertical fixed-irradiation-ports, and the other is a rotating-gantry port. For all ports, fast three-dimensional raster-scanning irradiation technology is employed. The rotating gantry equips ten combined-function superconducting magnets, and can deliver carbon ions having the energy of between E = 430 and 50 MeV/ u to an isocenter with irradiation angles of over ±180°. Construction as well as installation of the superconducting gantry was completed by the end of September 2015, and treatments using the gantry began since May 2015. Presently, we are further designing a next-generation compact facility as a future project; superconducting and laser technologies are to be used for accelerator design. In this paper, we report development of carbon-ion accelerator facilities as well as the future project.

Multiple-energy synchrotron operation was developed to realize fast 3D scanning irradiation for carbon-ion radiotherapy. This type of operation can output various carbon-ion beams with different energies in a single synchrotron cycle. The beam control system used in this kind of operation was developed to quickly provide the beam energy and intensity required from the irradiation control system. The performance of the system was verified by experimental tests. The system could output beams of 197 different energies in 63 s. The beam intensity could be controlled for all the output beams without large ripples or overshooting. The experimental test of irradiation for prostate cancer treatment was also successfully performed, and the test results proved that our system can greatly reduce the irradiation time.

The introduction of a heavy-ion rotating gantry is in progress at the Heavy Ion Medical Accelerator in Chiba (HIMAC) for realizing high-precision cancer therapy using heavy ions. A scanning irradiation method will be applied to this gantry course with 48–430 MeV/u beam energy. In the rotating gantry, the horizontal and vertical beam parameters are coupled by its rotation. To maintain a circular spot shape at the isocenter irrespective of the gantry angle, achieving symmetric phase space distribution of the horizontal and vertical beam at the entrance of the rotating gantry is necessary. Therefore, compensating the horizontal and vertical emittance is necessary. We consider using a thin scatterer method to compensate the emittance. After considering the optical design for emittance matching, the scatterer device is located in the high-energy beam transport line. In the beam commissioning, we confirm that the symmetrical spot shape is obtained at the isocenter without depending on the gantry angle.

At Heavy Ion Medical Accelerator in Chiba (HIMAC) in National Institute of Radiological Sciences (NIRS), more than 9000 patients have been successfully treated by carbon ion beams since 1994. The successful results of treatments have led us to construct a new treatment facility equipped with a three-dimensional pencil beam scanning irradiation system, which is one of sophisticated techniques for cancer therapy with high energetic ion beam. This new facility comprises two treatment rooms having fixed beam lines and one treatment room having rotating gantry line. The challenge of this project is to realize treatment of a moving target by scanning irradiation. Thus, to realize this, the development of the fast scanning system is one of the most important issues in this project. After intense commissioning and quality assurance tests, the treatment with scanned ion beam was started in May 2011. After treatment of static target starts, we have developed related technologies. As a result, we can start treatment of moving target and treatment without range shifter plates since 2015. In this paper, the developments of the scanning irradiation system are described.