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We confirmed the effect of ion recombination using a parallel-plate ionization chamber: dose monitor for clinical use and the Advanced Markus chamber. A 290 MeV/u carbon-ion beam was irradiated using the continuous spot-scanning method in a field size of 5 cm by 5 cm with 2 mm spacing. We tested three beam intensities (1.35×10^8, 2.69×10^9, and 4.03×10^9 particle per second (pps)) at two linear energy transfers (12 keV/μm and 200 keV/μm). The charge (Q) was measured by changing the voltage of the Advanced Markus chamber and that of the dose monitor. Then, Boag’s method was used to calculate the saturated charge (Qsat ). For the Advanced Markus chamber, 300 V is a sufficient potential to collect charge. For the dose monitor, Qsat/Q at 2500 V was 1.024 for 4.03×10^9 pps, indicating that the general recombination correction cannot be ignored when high dose rate treatment is performed using a carbon-ion scanning beam.

Three-dimensional (3D) pencil-beam scanning is an ideal irradiation technique to make the best use of the characteristics of a carbon-ion beam and to provide flexible dose delivery. To suppress beam spread due to multiple scattering and nuclear reactions, we developed a full energy scanning method. In some cases, such as eye treatments, the irradiation fields are very small and short ranged. Accordingly, we prepared a minimum low-energy carbon-ion beam corresponding to water-equivalent residual ranges of less than 2 mm. We performed experimental verification for low-energy carbon-ion beams ranging from 55.6 to 96.0 MeV/u. The accuracy of 3D dose delivery with the low-energy carbon-ion beam was verified by measuring the dose distributions for different target volumes. The results confirmed that the measured dose distributions agree well with the calculated ones. Then, the first eye treatment with low-energy carbon-ion beam to a patient was performed in 2018.

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.

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 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.

Heavy ion cancer therapy with the Heavy ion Medical Accelerator synchrotron in Chiba (HIMAC) has been administered to more than 10,000 patients since 1994. We started the heavy-ion cancer therapy using a 3D scanning irradiation system in May 2011, at New Particle Therapy Research Facility in NIRS. To enhance the treatment quality by achieving a precise dose control, we have continued some R&Ds on HIMAC and its irradiation system including a superconductingrotating gantry. Since 2016, we have started developments of a compact superconducting rotating gantry and a compact superconducting synchrotron to be applied for a newly started project of a “quantum scalpel” that is a next generation of the heavy-ion cancer therapy machine. We also started R&Ds for the intensity modulated multi-ion therapy that is applied to improve outcomes of the refractory cancer treatment. This paper outlines those R&Ds as well as the present status of HIMAC accelerator facility.

放射線医学総合研究所（放医研）は、1993年に重粒子線がん治療用加速器HIMACを建設し、炭素イオンを用いた重粒子線がん治療を行ってきた。1994年の治療開始から今年で27年目を迎え、現在までの重粒子がん治療の登録患者数は延べ12000人以上となっている。2010年にはHIMACの既存施設に連結する形で新治療研究棟を建設し、複雑な腫瘍形状や治療期間中における腫瘍形状の変化にも対応可能な三次元スキャニング照射法を適用した治療を2011年から開始している。また、2017年からは超伝導電磁石を用いた回転ガントリー照射装置による治療も開始され、0-360度の角度範囲から任意の方向を選択して照射できるようになり、より良い治療成果が期待されている。 現在放医研では、レーザー駆動イオン加速技術を用いた入射器やシンクロトロンへの超伝導電磁石技術の適用などによって実現される次世代重粒子線治療装置「量子メス」の研究開発を進めている。量子メスでは、複数のイオン種を組み合わせて照射するマルチイオン照射法の確立による難治性がんの治療成績向上や治療期間の短縮などの治療高度化も目指しており、それに関連した研究開発もあわせて進められている。本発表では、最近の研究開発の概要を紹介するとともに、運用の現状について報告を行う。, 第17回日本加速器学会年会

Introduction: In the 7 years since our facility opened, we have treated > 2000 patients with pencil-beam scanned carbon-ion beam therapy. Methods: To summarize treatment workflow, we evaluated the following five metrics: i) total number of treated patients; ii) treatment planning time, not including contouring procedure; iii) quality assurance (QA) time (daily and patient-specific); iv) treatment room occupancy time, including patient setup, preparation time, and beam irradiation time; and v) daily treatment hours. These were derived from the oncology information system and patient handling system log files. Results: The annual number of treated patients reached 594, 7 years from the facility startup, using two treat- ment rooms. Mean treatment planning time was 6.0 h (minimum: 3.4 h for prostate, maximum: 9.3 h for eso- phagus). Mean time devoted to daily QA and patient-specific QA were 22 min and 13.5 min per port, respec- tively, for the irradiation beam system. Room occupancy time was 14.5 min without gating for the first year, improving to 9.2 min (8.2 min without gating and 12.8 min with gating) in the second. At full capacity, the system ran for 7.5 h per day. Conclusions: We are now capable of treating approximately 600 patients per year in two treatment rooms. Accounting for the staff working time, this performance appears reasonable compared to the other facilities.

To make the best use of the characteristics of a carbon-ion beam and provide flexible dose delivery, three-dimensional (3D) pencil-beam scanning is an ideal irradiation technique. To suppress beam spread due to multiple scattering and nuclear reactions, we then developed a full energy scanning method. In some case such as eye treatment, the irradiation fields are very small and short range. Thus, we prepared a minimum low energy carbon-ion beam corresponding to the water-equivalent residual ranges less than 2 mm. In our presentation, we introduce the experimental verification for low energy carbon-ion beam., 13th European Conference on Accelerators in Applied Research and Technology (ECAART13)

Since 1984, when HIMAC project was initiated, NIRS has been leading the development of heavy ion therapy system. We have been developing cutting-edge technologies, such as fast scanning and superconducting gantry. In the development of the new treatment facility of NIRS-HIMAC, it was great challenge to realize treatment of a moving target by scanning irradiation. In order to realize this, the development of the fast scanning system is one of the most important issues in this project. The treatment with scanned ion beam was started in May 2011, and treatment of moving target was started in March 2015. In parallel with the scanning development, we developed sophisticated accelerator control, i.e. multiple energy operation, and superconducting gantry. The multiple energy operation makes it possible to deliver different beam energies in single synchrotron cycle. The time to change beam energy is suppressed within 0.3 seconds by means of this operation. In addition, this operation gives us smaller beam size, because range shifter plates are not necessary. From September 2015, we started the routine use of more than 200 energy steps. The construction of superconducting gantry was completed in 2015 and started clinical operation in 2017. Throughout these works, we have experienced a lot of acceptance tests and commissioning for therapeutic carbon ion beams. Furthermore, QA, as a verification of accepted performance constancy, should be routinely programmed. In this talk, above described progress and related practical works will be introduced., YCC - QST-NIRS Joint symposium

National Institute of Radiological Sciences (NIRS) has performed carbon-ion radiotherapy since 1994 using the Heavy Ion Medical Accelerator in Chiba (HIMAC) which is the world’s first heavy-ion accelerator facility dedicated to medical use. The treatments with the carbon-ion beams have been successfully carried out for more than 10000 patients in the NIRS. Now, the NIRS has investigated multiple-ion therapy with the energetic beams of more than two ion species to improve outcomes of the refractory cancer treatment. By appling the multiple-ion beams for treatment irradiation, we become controllable not only the dose but also the linear energy transfer (LET), which concerns with the biological effect, in the target volume. To realize multiple-ion therapy, it is required that the accelerator control system can switch the ion species, energy and intensity of the output beams quickly in the treatment session. For this purpose, we have studied the switching method of the multiple-ion beams using multiple-energy operation at the HIMAC. Since this method accelerates the multiple-ion beams with the charge-to-mass ratio Q/A of 1/2 without changing the magnetic operation pattern of the synchrotron, the irradiation ion species can be changed only by switching the ion sources and the injector parameters. Therefore, this method can perform the fast switching of the irradiation ion species. In addition, because of the use of the same magnetic operation pattern, we can reduce the time for the commissioning and daily adjustments of the multiple-ion beams. In this paper, we describe our accelerator control method for multi-ion therapy operation and the results of the beam experiments at the HIMAC., 13th European Conference on Accelerators in Applied Research and Technology (ECAART13)

Purpose: Three-dimensional irradiation with a scanned carbon-ion beam has been performed from 2011 at our facility. We have been developed the rotating-gantry equipped with the scanning irradiation system. The number of combinations of beam properties to measure for the commissioning is more than 7200, i.e. 201 energy steps, 3 intensities, and 12 gantry angles. To compress the commissioning time, quick and simple range verification system is required. In this work, we develop quick range verification system using scintillator and CCD (charge-coupled device) camera and estimate the accuracy of the range verification. Methods: A cylindrical plastic scintillator block and a CCD camera were installed on the black box. The optical spatial-resolution of the system is 0.2 mm/pixel. The camera control system was connected and communicates with the measurement system that is part of the scanning system. The range was determined by image processing. Reference range for each energy beam was determined by a difference of Gaussian (DOG) method and the 80 percent of distal dose of the depth dose distribution that were measured by a large parallel-plate ionization chamber. We compared a threshold method and a DOG method. Results: We found that the edge detection method (i.e., the DOG method) is best for the range detection. The accuracy of range detection using this system is within 0.2 mm, and the reproducibility of same energy measurement is within 0.1 mm without setup error. Conclusions: The results of this study demonstrate that our range check system is capable of quick and easy range verification with sufficient accuracy.

Purpose: Accurate dose measurement in radiotherapy is critically dependent on correction for gain drop, which is the difference of the measured current from the ideal saturation current due to general ion recombination. Although a correction method based on the Boag theory has been employed, the theory assumes that ionized charge density in an ionization chamber (IC) is spatially uniform throughout the irradiation volume. For particle pencil beam scanning, however, the charge density is not uniform, because the fluence distribution of a pencil beam is not uniform. The aim of this study was to verify the effect of the nonuniformity of ionized charge density on the gain drop due to general ion recombination. Methods: The authors measured the saturation curve, namely the applied voltage versus measured current, using a large plane-parallel IC and 24-channel parallel-plate IC with concentric electrodes. To verify the effect of the nonuniform ionized charge density on the measured saturation curve, we calculated the saturation curve using a method which takes into account the nonuniform ionized charge density and compared it with the measured saturation curves. Results: Measurement values of the different saturation curves in the different channels of the concentric electrodes differed, and were consistent with the calculated values. The saturation curves measured by the large plane-parallel IC were also consistent with the calculation results, including the estimation error of beam size and of setup misalignment. Although the impact of the nonuniform ionized charge density on the gain drop was clinically negligible with the conventional beam intensity, it was expected that the impact would increase with higher ionized charge density. Conclusions: For pencil beam scanning, the assumption of the conventional Boag theory is not valid. Furthermore, the nonuniform ionized charge density affects the prediction accuracy of gain drop when the ionized charge density is increased by a higher dose rate and/or lower beam size.

A superconducting magnet gantry has been used at HIMAC in NIRS, transporting beams for carbon ion radiotherapy. A second superconducting gantry, with a different design, is under construction in Yamagata University. This invited talk presents an overview of these gantry designs, their advantages for light ion radiotherapy, their operational experiences, and future perspectives for superconducting radiotherapy gantries., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

Purpose: At the National Institute of Radiological Sciences (NIRS), we have been commissioning the rotating- gantry system for the carbon-ion radiotherapy in 2015. It is world’s first rotating-gantry with super-conducting magnet and achieved a more compact, lighter rotating gantry than the typical gantry. During the commissioning of the rotating gantry, we adjusted the beam position using a steel sphere located at isocenter and verified the accuracy using a scintillation screen and CCD system. We employ the digital QA system to verify the geometrical accuracy easily and quickly. \nMethods: The 300 ton rotating gantry can deliver carbon ions having 430 MeV/u to the isocenter over 360 degrees, having the capability of performing three-dimensional scanning irradiation. the mechanical isocenter was verified using the laser tracker system. To verify the coincidence of the isocenter for irradiation system and the patient positioning system, we used a steel sphere located at isocenter. As a part of the verifying of the treatment beam position, scintillation screen viewed by a CCD camera mounted on the gantry downstream of the sphere. Total 201energy carbon beams with that were in the range from 48 to 430 MeV/u were measured sequentially. A starshot test was also performed to verify the gantry angle and beam direction visually using a scintillator block and a CCD camera. For the starshot test, 13 beam energy were selected. \nResults: From the result of the test using a sphere, the maximum displacement of the beam position was within 0.5mm at all gantry angles. The gantry starshot shows accuracy of the gantry angle was less than 0.5 degree. \nConclusion: The isocentricity of the compact super-conducting rotating gantry for carbon ion therapy dedicated to the highly precise treatment were within 1mm. Two of digital measurement system brought high-efficient beam adjusting and commissioning., 59th AnnualMeeting of American association of Physicists in Medicine (AAPM2017)

For our particle therapy society, this 10-20 years was transition phase form the passive delivery to the scanning delivery. In this transition from passive delivery, scanning delivery needs to keep specifications of 1) capability to treat moving tumor, 2) same or better dose rate, and 3) better dose conformation. Thus, the development of scanning system has been focused on faster scanning and smaller beam size. As a result of development, our scanning system has been treating the patients including moving target in both NIRS and KCC. Treating moving tumor with fast rescanning was one of important milestone in our society. However, next step of the development is strongly required, which means compact system with lower cost while keeping system performance. For this purpose, we have developed ultra-compact scanning magnet, which is really revolutionary device. This brand-new magnet makes the scanning system amazingly compact from 8 m to 3.5 m. Further, this new scanning system can deliver the field size of 34 cm x 34 cm. Not only a conceptual design, a prototype of this magnet is already manufactured and tested with carbon ion beam. Results of the beam test were successful and suitable for clinical use. Since smaller beam size is also important issue, we newly designed the irradiation port having a movable nozzle for further reduction of beam size, cooperating with the range shifter-less system. In this presentation, we will report this brand-new scanning system, which will be installed upcoming facilities., 56th Annual Conference of the Particle Therapy Co-operative Group (PTCOG56)

An isocentric superconducting rotating-gantry for heavy-ion therapy is being developed. This rotating gantry can transport heavy ions having 430 MeV/u to an isocenter with irradiation angles of over +- 180 , and is further capable of performing fast raster-scanning irradiation. For the magnets, combined- function superconducting-magnets are to be employed. All of the superconducting magnets have been designed, and their magnetic-field distributions were calculated by using a 3D electromagnetic-field solver. With the calculated magnetic-fields, beam-tracking simulations were performed to evaluate the field quality of the superconducting magnets. Beam profiles as well as phase-space distributions at the isocenter, as calculated by simulations, agreed well with those of linear beam-optics calculations, proving validity of the final design for the magnets. Three superconducting magnets were manufactured, and are being tested. In this paper, results of tracking simulations as well as test results for the superconducting magnets are presented.

A superconducting rotating-gantry for carbon radiotherapy was developed. This isocentric rotating gantry can transport carbon ions with the maximum energy of 430 MeV/u to an isocenter with irradiation angles of over 0-360 degrees, and is further capable of performing three-dimensional raster-scanning irradiation. The combined-function superconducting magnets were employed for the rotating gantry. The superconducting magnets with optimized beam optics allowed a compact gantry design with a large scan size at the isocenter; the length and the radius of the gantry are approximately 13 and 5.5 m, respectively, which are comparable to those for the existing proton gantries. The total weight of the gantry is estimated to be approximately 300 tons, which is roughly half of the existing gantry for carbon radiotherapy. A construction of the gantry structure begun since early 2014, and the installation of the entire gantry system to the Heavy Ion Medical Accelerator in Chiba (HIMAC) complex at National Institute of Radiological Sciences (NIRS) completed by the end of September, 2015. Beam commissioning subsequently begun since October, 2015, and carbon beams, as accelerated by the HIMAC upper synchrotron, having kinetic energy of between 430-48 MeV/u were successfully transported with the rotating gantry to the isocenter. The size and shape of the beam spots at the isocenter were finely tuned over various combinations of the beam energies and the gantry angle. We will present the recent progress as well as the current status of the superconducting rotating-gantry., The Workshop on Accelerator Operations 2016 (WAO2016)

A superconducting rotating-gantry for carbon radiotherapy was developed. This isocentric rotating gantry can transport carbon ions with the maximum energy of 430 MeV/u to an isocenter with irradiation angles of over ±180 degrees, and is further capable of performing three-dimensional raster-scanning irradiation. The combined-function superconducting magnets were employed for the rotating gantry. The superconducting magnets with optimized beam optics allowed a compact gantry design with a large scan size at the isocenter; the length and the radius of the gantry are approximately 13 and 5.5 m, respectively, which are comparable to those for the existing proton gantries. The total weight of the gantry was estimated to be approximately 300 tons, which is roughly half of the existing gantry for carbon radiotherapy. A construction of the gantry structure begun by 2014, and the installation of the entire gantry system to the Heavy Ion Medical Accelerator in Chiba (HIMAC) complex at National Institute of Radiological Sciences (NIRS) completed by the end of September, 2015. Beam turning begun by October, 2015, and carbon beams, as accelerated by the HIMAC synchrotron, having maximum energy of 430 MeV/u are transported with the rotating gantry to the isocenter. The size and shape of the beam spots at the isocenter were finely tuned over various combinations of the beam energies and the gantry angle. We will present the recent progress as well as the current status of the superconducting rotating-gantry., The 12th European Conference on Accelerators in Applied Research and Technology (ECAART12)

Control of the beam position for three-dimensional pencil-beam scanning is important because the position accuracy of the beam significantly impacts the alignment of the irradiation field. To suppress this effect, we have developed a simple procedure for beamline tuning. At first, beamline tuning is performed with steering magnets and fluorescent screen monitors to converge beam’s trajectory to central orbit. Misalignment between beam position and reference axis is checked by the verification system, which consists of the screen monitor and acrylic phantom. If the beam position is deviated from the reference axis, two pairs of steering magnets which are placed on downstream of the beam transport line will be corrected. These adjustments are iterated until the deviations for eleven energies of the beam are within 0.5 mm of the reference axis. To demonstrate the success of our procedure, we performed beam commissioning at the Kanagawa Cancer Center using our procedure., The 12th European Conference on Accelerators in Applied Research and Technology (ECAART12)

The National Institute of Radiological Sciences (NIRS) has performed carbon-ion radiotherapy on more than 9000 patients since 1994 and began the treatment with pencil beam scanning from 2011. Multiple-energy synchrotron operation was developed to realize fast 3D scanning irradiation at the Heavy Ion Medical Accelerator in Chia (HIMAC) in NIRS. It can provide carbon-ion beams with various energies ranging from 48 to 430 MeV/n in a single synchrotron cycle. To make use of its advantage, a fast beam chopper system has been installed in the high-energy beam transport (HEBT). This system is used to prevent uncontrollable spilled beams, which is caused by varying the beam energy, being delivered to the irradiation port. The changes of the beam energy can be performed quickly and reliably by using the HEBT chopper system. In addition, the intensity control system of the extracted beam has been equipped to save the irradiation time. It can lead a fast scanning sequence by keeping the beam intensity high within the limits determined by the performance of the magnet power supplies and so on. The irradiation tests were carried out to verify the performance of the beam control system using multiple-energy operation. The system could output the beams of more than 140 different energies in 60 seconds. The output beam intensity could be controlled for their energies without large ripple and overshoot. Experimental irradiation for prostate cancer treatment was also successfully performed, and its result proved that our system can greatly reduce the irradiation time., The 12th European Conference on Accelerators in Applied Research and Technology (ECAART12)

To make the best use of the characteristics of a carbon-ion beam and provide flexible dose delivery, three-dimensional (3D) pencil-beam scanning is an ideal irradiation technique. As part of the efforts to achieve ion-scanning therapy, a new treatment facility equipped with a 3D scanning irradiation system was constructed as an extension to the existing HIMAC. The 3D scanning irradiation system has been utilized for treatment since 2011. At present, for depth direction, the hybrid depth scanning method has been employed, in which 11 beam energies ranging from 140 to 430 MeV/u are used in conjunction with the range shifter. To suppress the beam spread due the multiple scattering and the nuclear reaction, we have developed a full energy scanning method (FES). In FES, we prepared more than 200 energy steps with 1 or 2 mm intervals. To obtain the range of less than 1 mm without using an energy absorber such as a range shifter, the minimum energy is chosen as 55.6 MeV/u. Generally, a long time is required for accelerator tuning and beam commissioning tests for treatment by FES. In our presentation, we introduce the beam commissioning for FES in a short period of time and the performance of FES is evaluated., The 12th European Conference on Accelerators in Applied Research and Technology (ECAART12)

Thanks to its characteristic depth-dose distribution with a Bragg peak, particle radiotherapy provides high dose localization to a tumor and is an effective tool for cancer therapy. The National Institute of Radiological Sciences (NIRS) in Japan has provided the particle radiotherapy with carbon-ion beam since 1994 using the Heavy-Ion Medical Accelerator in Chiba (HIMAC). To maximize characteristic advantage of the carbon-ion beams, the NIRS introduced a three-dimensional (3D) pencil beam scanning system in 2011. The pencil beam scanning system achieves conformal dose distribution to the tumor by superposing a dose deposit of the individual pencil beam. Since the high irradiation accuracy of beam position is required due to the sharpness of the Bragg peak, a device called as ridge filter is usually used to spread the Bragg peak size. The ridge filter has periodic stepped structure in one direction and a unit of the stepped structure called as a ridge bar. Since the energy loss of the scanned pencil beam depends on the thickness of the ridge bar the beam passed through, the energy distribution of the beam is spread. When the lateral pencil beam size is constant, the ridge filter with densely packed ridge bars is preferred because the particles with different energy is more mixed and the Bragg peak spread as planned. Since the pencil beam with smaller lateral beam size provides higher dose conformation the tumor, the pencil beam size has been improved to be small approximately 1-2 mm. Recently, it is difficult to pack the sufficient number of ridge bar within the lateral pencil beam region due to manufacturing limitation and a new designed ridge filter is required to realize more accurate irradiation by using the pencil beam with smaller beam size. We have designed the new ridge filter with honeycomb geometry. The new ridge bar has a structure stacked a hexagonal plate and periodically arranged the ridge bar to be honeycomb geometry. Since the packed density of the new ridge bar is higher than that of the conventional ridge bar, it is expected that the new ridge filter with honeycomb geometry gives the spread Bragg peak as planned when the beam size is below 1 mm. We have verified the advantages of the new ridge filter with honeycomb geometry by the calculation using particle tracking and the measurement of dose distribution. We will show the measurement and calculation results and that the new ridge filter is more useful for the pencil beam scanning with the smaller beam size., The 12th European Conference on Accelerators in Applied Research and Technology (ECAART12)

Three-dimensional (3D) pencil-beam scanning technique has been utilized since 2011 at the Heavy Ion Medical Accelerator in Chiba (HIMAC). At present, for depth direction, the hybrid depth scanning method has been employed, in which 11 beam energies ranging from 140 to 430 MeV/u are used in conjunction with the range shifter. To suppress the beam spread due the multiple scattering and the nuclear reaction, we have developed a full energy scanning method (FES). In FES, we prepared more than 200 energy steps with 1 or 2 mm intervals. To obtain the range of less than 1 mm without using an energy absorber such as a range shifter, the minimum energy is chosen as 55.6 MeV/u. Generally, a long time is required for accelerator tuning and beam commissioning tests for treatment by FES. In our presentation, we introduce the beam commissioning for FES in a short period of time and the performance of FES is evaluated., The 55th Annual Conference of the Particle Therapy Co-operative Group (PTCOG55)

In moving target irradiation with a scanned ion beam, the interplay effect between the target motion and scanned beams is a major and well-known problem, which can result in over or under dosage in the target volume. To overcome this problem, we developed fast scanning irradiation system with gating system for moving target. We started the treatment of a moving target by scanning irradiation to the first patient as a clinical study on March 4, 2015. In our presentation, the commissioning of moving target irradiation with pencil beam scanning are reported. To ensure the validity of both the delivered dose and the gating system, patient-specific quality assurance (QA) for moving target irradiation requires an additional procedure. We describe a new patient-specific QA procedure for moving target irradiation and experience with patient-specific QA., The 55th Annual Conference of the Particle Therapy Co-operative Group (PTCOG55)

We have developed a verification tool of a 2D fluence distribution for evaluation of scanned beam accuracy. The 2D fluence distributions of all slices are measured and recorded with a beam position monitor using a multi-wire proportional chamber during irradiation. Using a beam irradiation pattern file, the verification tool calculates the 2D fluence distributions on the plane that the beam position monitor is located. Moreover, the tool evaluates the effect of the accuracy of scanned beam delivery on the 2D fluence distributions by comparing the measured fluence distributions with calculated ones. Fig. 1 shows an example result of the 2D fluence based verification. For the patient-specific QA of this irradiation, it was difficult to evaluate the dose distribution measured by the conventional method using a 2D ionization chamber and a water phantom, since the number of evaluated point was less than 10. We tried to apply the 2D fluence based verification as additional check of scanned beam delivery. The γ-analysis of the 2D fluence distribution of each slice passed the acceptable pass rate of 90% and the result helped us to confirm the beam irradiation accuracy for this patient. The verification tool of 2D fluence distribution is a useful to ensure accurate beam delivery for pencil beam scanning. We will present the method for utilization of this tool in more detail, which includes the calculation method using a pencil beam profile measured with the beam position monitor and the verification method of the measured fluence distribution accuracy., The 55th Annual Conference of the Particle Therapy Co-operative Group (PTCOG55)

At Heavy Ion Medical Accelerator in Chiba (HIMAC), 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 (PBS) irradiation system. After the construction of fixed beam lines, we start design and construction of a superconducting rotating gantry. The construction of rotating gantry is completed in September 2015. This gantry can provide the beam energy ranging from 50 to 430 MeV/u. Since the rotating gantry system requires that the beam profiles at the iso-center have no correlation between the rotation angles, we employ thin scatter method. After the commissioning of beam transport line, we have started the commissioning of PBS system. Our PBS system is designed to treat moving target with fast rescanning as same as that of fixed beam line. In this presentation, we will report the present status of commissioning of our gantry and related beam tests., The 55th Annual Conference of the Particle Therapy Co-operative Group (PTCOG55)

As part of the Kanagawa "Challenge-10-year strategy to cancer" it was decided in March 2005 to establish a carbon-ion therapy system at the Kanagawa Cancer Center (KCC). From around 2009, the basic design and the foundational planning of the facility were considered and in January 2012 a contract was made with the Toshiba Corp. In December of the same year, construction of the main building for the acceleration and treatment devices has been started and completed in October 2014. Currently, the KCC is in a commissioning phase with the aim to start treatment in December this year. Various treatments for cancer, which include four present photon LINAC for the radiation therapy, will be provided to patients in cooperation with our cancer center hospital. In addition, we will combine a compact dissemination treatment system of carbon-ion therapy to the pencil beam 3D scanning technique designed by the National Institute of Radiological Sciences (NIRS). The treatment experience with the carbon-ion scanning technique is expected to be the second in the country following NIRS. In this presentation, we will report on the progress of the beam commissioning of the scanning system., Proceedings of the 13th Heavy Ion Accelerator Technology Conference, HIAT2015, Yokohama, Japan

It's important to control the beam position for the 3D pencil-beam scanning because the position accuracy of the beam has a serious matter on the alignment of the irradiation field. In order to suppress this matter, we have been developed a simple procedure for the beam tuning. The fluctuation of the beam position is tuned with the steering magnets (ST) and the fluorescent screen monitors (SCN). At first, the beam positions are measured by two SCN and the kick angles of two ST are calculated using deviates from the center of the beam position measured by SCN and the transfer matrix. After the tuning, the beam position at the isocenter is checked on the verification system for the alignment of the beam consists of the SCN and the iron sphere phantom. If the beam position is deviated from the center, one of ST placed on most downstream of the beam transport line will be corrected. These adjustments are iterated until the deviation for all energies of the beam are within 0.5 mm. We have been performed the beam commissioning using our procedure in Kanagawa Cancer Center. In this presentation, we will report on the result of these measurements., Proceedings of the 13th Heavy Ion Accelerator Technology Conference, HIAT2015, Yokohama, Japan

A superconducting rotating-gantry for carbon therapy is being developed. This isocentric rotating gantry can transport carbon ions with the maximum energy of 430 MeV/u to an isocenter with irradiation angles of over 0-360 degrees, and is further capable of performing three-dimensional raster-scanning irradiation. The combined-function superconducting magnets were employed for the rotating gantry. The superconducting magnets with optimized beam optics allowed a compact gantry design with a large scan size at the isocenter; the length and the radius of the gantry are approximately 13 and 5.5 m, respectively, which are comparable to those for the existing proton gantries. Furthermore, the maximum scan size at the isocenter is calculated to be as large as approximately 200 mm square for heavy-ion beams at the maximum energy of 430 MeV/u. A construction and installation of the superconducting gantry is in progress, and beam commissioning will begin from this autumn. We will present a status of the superconducting rotating-gantry., Proceedings of the 13th Heavy Ion Accelerator Technology Conference, HIAT2015, Yokohama, Japan