Korea Heavy Ion Medical Accelerator Research Articles

Estimation of the medical need for carbon-ion radiotherapy in Korea.

The Korea Heavy Ion Medical Accelerator project focuses on the development of medical accelerator facilities for delivering carbon-ion beams to cancer patients. The purpose of the present study was to estimate the clinical need for carbon-ion therapy in Korea. Seven tumor sites, namely head and neck, liver, lung, colon and rectum, prostate, bone and soft tissue, and pancreas were selected as eligible sites for receiving carbon-ion radiotherapy (RT) by radiation oncologists of the Korea Institute of Radiological and Medical Sciences. Cancer incidence data for the selected tumor sites were obtained from the Korea National Cancer Incidence Database in order to estimate the potential medical need for carbon-ion RT. The carbon-ion RT adaption rate was assessed based on the clinical experience of other carbon-ion therapy facilities. An estimation model was constructed for estimating the medical need for carbon-ion RT, and from this, 25 606 patients were deemed to be potential candidates for carbon-ion RT. This estimated potential need corresponded to 10% of newly diagnosed cancer patients in Korea. The realistic estimation was calculated as ranging between 4000 and 6300 patients, depending on the carbon-ion RT adaptation rate. This estimated medical need corresponded to 2–3% of newly diagnosed cancer patients in Korea. Taken together, our findings suggest that there is a clear medical need for carbon-ion RT in Korea, with at least 4000 potential patients per year.

Start-to-end simulations for beam dynamics in the injector system of the KHIMA heavy ion accelerator

The Korea Heavy Ion Medical Accelerator (KHIMA) project has been developed for cancer therapy. The injector system consists of a low energy beam transport (LEBT) line, a radio-frequency quadrupole, a drift tube linac with two tanks, and a medium energy beam transport (MEBT) line with a charge stripper section. The injector system transports and accelerates the 12C4+ beam that is produced from electron cyclotron resonance ion source up to 7MeV/u, respectively. The 12C6+ beam, which is transformed by a charge stripper from the 12C4+ beam, is injected into a synchrotron and accelerated up to 430MeV/u. The lattice for the injector system was designed to optimize the beam parameters and to meet beam requirements for the synchrotron. We performed start-to-end simulations from the LEBT line to the MEBT line to confirm that the required design goals of the beam and injector system were met. Our simulation results indicate that our design achieves the required performance and a good transmission efficiency of 90%. We present the lattice design and beam dynamics for the injector system in the KHIMA project.

Beam dynamics and error study of the medium energy beam transport line in the Korea Heavy-Ion Medical Accelerator

The Korea Heavy Ion Medical Accelerator consists of an injector and a synchrotron for an ion medical accelerator that is the first carbon-ion therapy system in Korea. The medium energy beam transport(MEBT) line connects the interdigital H-mode drift tube linac and the synchrotron. We investigated the beam conditions after the charge stripper by using the LISE++ and the SRIM codes. The beam was stripped from C4+ into C6+ by using the charge stripper. We investigated the performance of a de-buncher in optimizing the energy spread and the beam distribution in z-dW/W (direction of beam progress-beam and energy) phase. We obtained the results of the tracking simulation and the error analysis by using the TRACK code. Possible misalignments and rotations of the magnets were considered in the simulations. States of the beam were examined when errors occurred in the magnets by the applying analytic fringe field model in TRACK code. The condition for the beam orbit was optimized by using correctors and profile monitors to correct the orbit. In this paper, we focus on the beam dynamics and the error studies dedicated to the MEBT beam line and show the optimized beam parameters for the MEBT.

Development of a robotic patient positioning system with a wide beam-angle range for fixed-beam particle therapy

This paper describes a robotic patient positioning system (PPS) for a fixed-beam heavy-ion therapy system. In order to extend the limited irradiation angle range of the fixed beam, we developed a 6-degree-of-freedom (6-DOF) serial-link robotic arm and used it as the robotic PPS for the fixed-beam heavy-ion therapy system. This research aims to develop a robotic PPS for use in the Korea Heavy Ion Medical Accelerator (KHIMA) system, which is under development at the Korea Institute of Radiological & Medical Sciences (KIRAMS). In particular, we select constraints and criteria that will be used for designing and evaluating the robotic PPS through full consultation with KIRAMS. In accordance with the constraints and criteria, we develop a 6-DOF serial-link robotic arm that consists of six revolute joints for the robotic PPS, where the robotic arm covers the upper body of a patient as a treatment area and achieves a 15 ° roll and pitch angle in the treatment area without any collision. Various preliminary experiments confirm that the robotic PPS can meet all criteria for extension of the limited irradiation angle range in the treatment area and has a positioning repeatability of 0.275 mm.

Orbit error correction on the high energy beam transport line at the KHIMA accelerator system

For the purpose of treatment of various cancer and medical research, the synchrotron based medical machine under the Korea Heavy Ion Medical Accelerator (KHIMA) project have been conducted and is going to treat the patient at the beginning of 2018. The KHIMA synchrotron is designed to accelerate and extract the carbon ion (proton) beam with various energy range, 110 up to 430 MeV/u (60 up to 230 MeV). A lattice design and beam optics studies for the High Energy Beam Transport (HEBT) line at the KHIMA accelerator system have been carried out with WinAgile and the MAD-X codes. Because the magnetic eld errors and the mis-alignments introduce to the deviations from the design parameters, these error sources should be treated explicitly and the sensitivity of the machine's lattice to di erent individual error sources is considered. Various types of errors which are static and dynamic one have been taken into account and have been consequentially corrected with a dedicated correction algorithm by using the MAD-X program. As a result, the tolerances for the diverse error contributions have been speci ed for the dedicated lattice components in the whole HEBT lines.

Modeling the biophysical effects in a carbon beam delivery line by using Monte Carlo simulations

Relative biological effectiveness (RBE) plays an important role in designing a uniform dose response for ion beam therapy. In this study the biological effectiveness of a carbon ion beam delivery system was investigated using Monte Carlo simulation. A carbon ion beam delivery line was designed for the Korea Heavy Ion Medical Accelerator (KHIMA) project. The GEANT4 simulation tool kit was used to simulate carbon beam transporting into media. An incident energy carbon ion beam in the range between 220 MeV/u and 290 MeV/u was chosen to generate secondary particles. The microdosimetric-kinetic (MK) model is applied to describe the RBE of 10% survival in human salivary gland (HSG) cells. The RBE weighted dose was estimated as a function of the penetrating depth of the water phantom along the incident beam direction. A biologically photon-equivalent Spread Out Bragg Peak (SOBP) was designed using the RBE weighted absorbed dose. Finally, the RBE of mixed beams was predicted as a function of the water phantom depth.

Optimization of the multi-turn injection efficiency for a medical synchrotron

We present a method for optimization of the multi-turn injection effciency for medical synchrotron. We show that for given injection energy the injection efficiency can be greatly enhanced by choosing transverse tunes appropriately as well as optimizing the injection bump and the number of turns required for beam injection. We verify our study by applying the method to the Korea Heavy Ion Medical Accelerator (KHIMA) synchrotron which is currently built at the campus of Dongnam Institute of Radiological and Medical Sciences (DIRAMS) in Busan, Korea. First the frequency map analysis is performed with the help of ELEGANT and ACCSIM codes. The tunes which yield the good injection efficiency are then selected. With these tunes the injection bump and the number of turns required for injection are then optimized by tracking a number of particles up to one thousand turns after injection beyond which there is no further beam loss. Results for optimization of the injection efficiency for proton ion are presented.

SU‐F‐T‐213: Commissioning Results of the Prototype Active Scanning Irradiation System of Korea Heavy Ion Medical Accelerator

Purpose:A prototype actives scanning beam delivery system was designed, manufactured and installed as a part of the Korea Heavy Ion Medical Accelerator Project. The prototype system includes the most components for steering, modulating, detecting incident beam to patient. The system was installed in MC‐50 cyclotron beam line and tested to extract the normal operation conditions.Methods:The commissioning process was completed by using 45 MeV of proton beam. To measure the beam position accuracy along the scanning magnet power supply current, 25 different spots were scanning and measured. The scanning results on GaF film were compared with the irradiation plan. Also, the beam size variation and the intensity reduction using range shifter were measured and analyzed. The results will be used for creating a conversion factors for asymmetric behavior of scanning magnets and a dose compensation factor for longitudinal direction.Results:The results show asymmetry operations on both scanning × and y magnet. In case of scanning magnet × operation, the current to position conversion factors were measured 1.69 mm/A for positive direction and 1.74 mm/A for negative direction. The scanning magnet y operation shows 1.38mm/A and 1.48 mm/A for both directions. The size of incoming beam which was 18 mm as sigma becomes larger up to 55 mm as sigma while using 10 mm of the range shifter plate. As the beam size becomes large, the maximum intensity of the was decreased. In case of using 10 mm of range shifter, the maximum intensity was only 52% compared with no range shifter insertion.Conclusion:For the appropriate operation of the prototype active scanning system, the commissioning process were performed to measure the beam characteristics variation. The obtained results would be applied on the irradiation planning software for more precise dose delivery using the active scanning system.

SU‐F‐T‐149: Development of the Monte Carlo Simulation Platform Using Geant4 for Designing Heavy Ion Therapy Beam Nozzle

Purpose:The significant issue of particle therapy such as proton and carbon ion was a accurate dose delivery from beam line to patient. For designing the complex delivery system, Monte Carlo simulation can be used for the simulation of various physical interaction in scatters and filters. In this report, we present the development of Monte Carlo simulation platform to help design the prototype of particle therapy nozzle and performed the Monte Carlo simulation using Geant4. Also we show the prototype design of particle therapy beam nozzle for Korea Heavy Ion Medical Accelerator (KHIMA) project in Korea Institute of Radiological and Medical Science(KIRAMS) at Republic of Korea.Methods:We developed a simulation platform for particle therapy beam nozzle using Geant4. In this platform, the prototype nozzle design of Scanning system for carbon was simply designed. For comparison with theoretic beam optics, the beam profile on lateral distribution at isocenter is compared with Mont Carlo simulation result. From the result of this analysis, we can expected the beam spot property of KHIMA system and implement the spot size optimization for our spot scanning system.Results:For characteristics study of scanning system, various combination of the spot size from accerlator with ridge filter and beam monitor was tested as simple design for KHIMA dose delivery system.Conclusion:In this report, we presented the part of simulation platform and the characteristics study. This study is now on‐going in order to develop the simulation platform including the beam nozzle and the dose verification tool with treatment planning system. This will be presented as soon as it is become available.

Design Study of Main Dipole Magnets for Korea Heavy Ion Medical Accelerator Synchrotron

The Korea Institute of Radiological and Medical Science launched a project to construct an accelerator facility for carbon ion therapy, known as the Korea Heavy Ion Medical Accelerator (KHIMA), in April 2011. The development of the synchrotron for this facility began in 2014, and its main dipole magnets are currently in the design phase. In the study described herein, a simulation model of a main dipole magnet was created based on the Proton-Ion Medical Machine Study, and the basic parameters of the dipole magnets and their magnetic field requirements were investigated. The coil specifications were considered, and the pole profile was optimized to achieve the necessary magnetic field quality. Furthermore, the dynamic behavior of the modeled magnet was studied to estimate the effects of the eddy current and the driving voltage. The results of this design study are presented in this paper.

Design study of the KIRAMS-430 superconducting cyclotron magnet

Design study of superconducting cyclotron magnet for the carbon therapy was performed at the Korea Institute of Radiological and Medical Science (KIRAMS). The name of this project is The Korea Heavy Ion Medical Accelerator (KHIMA) project and a fixed frequency cyclotron with four spiral sector magnet was one of the candidate for the accelerator type. Basic parameters of the cyclotron magnet and its characteristics were studied. The isochronous magnetic field which can guide the 12C6+ ions up to 430MeV/u was designed and used for the single particle tracking simulation. The isochronous condition of magnetic field was achieved by optimization of sector gap and width along the radius. Operating range of superconducting coil current was calculated and changing of the magnetic field caused by mechanical deformations of yokes was considered. From the result of magnetic field design, structure of the magnet yoke was planned.

Radiation Protection Study for the First Korea Heavy-Ion Medical Accelerator Facility

Because of the encouraging results obtained at worldwide heavy-ion therapy facilities, the first hospital-based heavy-ion accelerator therapy facility is under construction in Busan, Korea, at the Korea Institute of Radiological and Medical Sciences. The compact accelerator will deliver beams of heavy ions, specifically carbon ions of energy 430MeV/u. This study focuses on radiation protection aspects concerning materials activation and facility shielding. Radiation shielding was evaluated with two different Monte Carlo codes (MCNPX and FLUKA), and materials activation studies were performed using FLUKA and a combination of MCNPX+CINDER’90 codes.

Design of the KHIMA synchrotron

The Korea Heavy Ion Medical Accelerator project (KHIMA) has been proposed as an ion-beam synchrotron facility for cancer therapy. The facility will be installed at Gijang, Busan with completion in 2017. The proposed maximum energy of the ions is 430 MeV/u (for carbon) to cover various tumor depths up to 30 cm. For the synchrotron design, we optimized the lattice configuration to fit the therapy. We discuss here the status of the synchrotron’s design.

Preliminary results, obtained by using a proton beam, for an active scanning system to installed on the KHIMA

The active scanning technique is a pencil beam delivery method in particle therapy. The active scanning beam delivery system consists of a beam scanner, beam monitor, energy modulator, and related programs, such as the irradiation control and planning programs. A proposed prototype active scanning system was designed and installed on MC-50 at the Korea Institute of Radiological and Medical Science (KIRAMS) with a 45-MeV proton beam. The laminated magnetic yoke of the scanning magnet supported fast ramping. The beam intensity and the beam profile monitors were designed for measuring the beam’s properties. Both the range shifter and the ridge filter modulate the incoming beam energy. The LabVIEW®-based beam-irradiation-control program operates the system in a sequential operation manner for use with the MC-50 cyclotron. In addition, an in-housecoded irradiation-planning program generates an optimal irradiation path. A scanning experiment was successfully completed to print the logo of the Korea Heavy Ion Medical Accelerator (KHIMA) on GaF film. Moreover, the beam’s position accuracy was measured as 0.62 mm in the x-direction and as 0.83 mm in the y-direction.

IH-DTL design with KONUS beam dynamics for KHIMA project

The Kombinierte Null Grad Struktur (KONUS) beam dynamics design of the interdigit H-mode drift tube linac (IH-DTL) for the Korea Heavy Ion Medical Accelerator (KHIMA) project is presented. We performed a KONUS beam dynamics simulation for a carbon beam (12C4+) with the LORASR code. The 12C4+ beam was accelerated from an input energy of 0.4MeV/u to an output energy of 7MeV/u by the IH-DTL operated at 200MHz. The optimization aims were to increase the transmission efficiency and to minimize the beam emittance growth, beam loss, and project costs. The buncher with two gaps and two quadrupole doublets were placed between the RFQ and the IH-DTL. The whole IH-DTL consists of two tanks, 56 acceleration gaps, and four quadrupole triplets. It achieves a transmission efficiency of 100%. The total length from the exit of the RFQ to the exit of the IH-DTL is approximately 507.7cm.

Development of a patient positioning error compensation tool for Korea Heavy-Ion Medical Accelerator Treatment Center

In this study, a potential validation tool for compensating for the patient positioning error was developed by using 2D/3D and 3D/3D image registration. For 2D/3D registration, digitallyreconstructed radiography (DRR) and three-dimensional computed tomography (3D-CT) images were applied. The ray-casting algorithm is the most straightforward method for generating DRR, so we adopted the traditional ray-casting method, which finds the intersections of a ray with all objects, voxels of the 3D-CT volume in the scene. The similarity between the extracted DRR and the orthogonal image was measured by using a normalized mutual information method. Two orthogonal images were acquired from a Cyber-knife system from the anterior-posterior (AP) and right lateral (RL) views. The 3D-CT and the two orthogonal images of an anthropomorphic phantom and of the head and neck of a cancer patient were used in this study. For 3D/3D registration, planning CT and in-room CT images were applied. After registration, the translation and the rotation factors were calculated to position a couch to be movable in six dimensions. Registration accuracies and average errors of 2.12 mm ± 0.50 mm for transformations and 1.23 ° ± 0.40 ° for rotations were acquired by using 2D/3D registration with the anthropomorphic Alderson-Rando phantom. In addition, registration accuracies and average errors of 0.90 mm ± 0.30 mm for transformations and 1.00 ° ± 0.2 ° for rotations were acquired by using CT image sets. We demonstrated that this validation tool could compensate for patient positioning errors. In addition, this research could be a fundamental step in compensating for patient positioning errors at the Korea Heavy-ion Medical Accelerator Treatment Center.

RF cavity design for KIRAMS-430 superconducting cyclotron

The Korea Heavy Ion Medical Accelerator (KHIMA) has developed a superconducting cyclotron for the carbon therapy, which is called KIRAMS-430. The cyclotron is designed to accelerate only 12C6+ ions up to the energy of 430MeV/u. It uses two normal conducting RF cavities. The RF frequency is about 70.76MHz. The nominal dee voltage is 70kV at the center and 160kV at the extraction. The RF cavity was designed with 4 stems by using CST microwave studio (MWS). In this paper, we represent the simulation results and the optimized design of the RF cavity for the KIRAMS-430.

Current design status of high energy beam transfer line for KHIMA project

The Korea heavy ion medical accelerator (KHIMA) project is developing and constructing the heavy ion medical accelerator for the first time in Korea since 2010. This paper describes the status of high energy beam transfer line (HEBT), which connects the superconducting cyclotron to the treatment rooms. The HEBT provides a patient with 145–430 MeV/u carbon (12C6+) beam to cure cancer. The HEBT is consisted of 6 beam lines (4 horizontal, 1 vertical and 1 oblique). The size of the design HEBT is 41 m in length, 11 m in width and 17 m in height. Total number of magnets is 53 for focusing magnets and 22 for bending magnets. In the description, the current design status of the HEBT is described.

Development of a control system for the 14.5 GHz ECR ion source

A control system of the 14.5 GHz electron cyclotron resonance (ECR) ion source has been designed and developed in KHIMA(Korea Heavy Ion Medical Accelerator) project which will use C6+ ions for heavy ion therapy. Production of the selected ion beam in stable operation with safety is a development goal with flexibility by easy access and modification which are necessary during development process with an accelerator. The control system of the ECR ion source system consists of electric control cabinet (ECC) as hardware and main control program (MCP) as software, respectively. ECC developed to manage power and control flow with electric components and controllers controls the injection system, RF system, high voltage & extraction system, analyzing system, vacuum system, cooling system, diagnosis system and safety system. MCP is the supervisory program developed for effective automation and data acquisition by LabVIEW-based graphical programming. The isolated network from a control computer to ECC and bleeder resistors in a steel plate box composed by the simulation result for high voltage power supplies increase reliability and safety. The performance of the developed control system has been verified successfully by beam extraction of C4+ ion from CO2 as main gas and He as support gas through an analyzing magnet and a faraday cup with the acquired spectrum at the control system. After optimization with C4+ ions, measurement of characteristics of C6+ ions including emittance of the ion beam will be planned early 2013. Also, quantity of C6+ ions in the same charge to mass ratio will be estimated by using 13CO2 as main gas and He as support gas.

Radio-frequency system of the KIRAMS-30 cyclotron for RI mass production

The KHIMA (Korea Heavy Ion Medical Accelerator) had developed the KIRAMS-30 cyclotron in collaboration with the ARTI (Advanced Radiation Technology Institute). This cyclotron is able to accelerate proton for the mass production of radioisotopes. It is designed to use two normal conduct RF cavities. The resonant frequency of the ion is 15.99 MHz because of the magnet design and the beam dynamics. The RF frequency is 63.96 MHz because of the 4th harmonic number. By using computer simulation codes, we estimated the principle design parameters of the RF system, we simulated the electric field distribution. In this paper, we present the design features, the results of quality assessment tests for the RF system, and important issues taken into consideration when designing such a cyclotron.