Ion Therapy Facility Research Articles

New accelerator designs: NIMMS

PurposeThis article summarises the presentation given at the “Hadrontherapy: status and perspectives” event.MethodsStructure, methodology, and objectives of the Next Ion Medical Machine Study collaboration are introduced. Its four Work Packages are: small synchrotrons for particle therapy, curved superconducting magnets for synchrotrons and gantries, superconducting gantry design, and high-frequency ion linacs. Synchrotrons under study include a superconducting design for carbon ion therapy, and a normal-conducting design for ions up to helium. Superconducting magnet R&D is carried out in two European projects. Within the scope of these projects, five magnet demonstrators with different technologies are in different phases of design and production. Beam optics and mechanical design of a superconducting gantry for carbon ions is being developed. A high-frequency linac design has been completed, and tests are starting on a prototype high-frequency injector.ResultsThe designs of two facilities based on NIMMS technological developments are presented. A carbon ion research and therapy facility was designed for the SEEIIST project, based on a conventional synchrotron with high beam intensity. A smaller facility aimed at cancer therapy and research with light ions, in particular helium beams has also been designed. Both facilities can produce FLASH-type beams.ConclusionsThe traditional design of carbon ion therapy facilities can be improved by adding new features as higher beam intensity and new beam extraction schemes. A cost-effective alternative to the traditional design is a compact facility for light ions, exploiting the potential for treatment with helium ions and allowing an experimental programme with different ion species.

Progress in heavy ion cancer therapy at IMP and future development

AbstractBasic research on heavy ion cancer therapy such as radiobiology, medical physics, and therapeutic technique has been conducted at the Institute of Modern Physics (IMP), Chinese Academy of Sciences since 1995. Based on the achievements acquired in the basic research and the requirements for a heavy ion accelerator for radiotherapy purposes, a dedicated heavy ion therapy facility named Heavy Ion Medical Machine (HIMM) was designed at IMP and constructed in Wuwei, China. The HIMM facility consists of two electron cyclotron resonance ion sources, one cyclotron as the injector and one synchrotron as the main accelerator, and four different treatment rooms equipped with passive or active beam delivery systems, and accelerates carbon ions up to 400 MeV/u. After the performance inspection of HIMM organized by the National Medical Device Inspection Center, preclinical tests like cell and animal radiobiological experiments and dosimetric verification using anthropomorphic phantoms for elucidating the biophysical properties of the carbon ion beams provided by HIMM were carried out. According to the Chinese medical device regulations, a clinical trial in which 46 tumor patients were recruited and two hospitals participated was conducted in the HIMM facility, aiming at evaluating the treatment safety and short‐term efficacy of the medical device. The success of the clinical trial helped the HIMM facility be authorized by the Chinese government as a class III medical device. In this paper, all the aspects mentioned above are introduced and discussed, and implications for future improvements are also given.

Commissioning and Validation of CT Number to SPR Calibration in Carbon Ion Therapy Facility

PurposeWe performed computed tomography (CT)—stopping power ratio (SPR) calibration in a carbon-ion therapy facility and evaluated SPR estimation accuracy. Materials and MethodsA polybinary tissue model method was used for the calibration of CT numbers and SPR. As a verification by dose calculation, we created a virtual phantom to which the CT-SPR calibration table was applied. Then, SPR was calculated from the change in the range of the treatment planning beam when changing to 19 different CT numbers, and the accuracy of the treatment planning system (TPS) calculation of SPR values from the CT-SPR calibration table was validated. As a verification by measurement, 5 materials (water, milk, olive oil, ethanol, 40% K2HPO4) were placed in a container, and the SPR was obtained by measurement from the change in the range of the beam that passed through the materials. ResultsThe results of the dose calculations of the TPS showed that the results agreed within 1% for the lower CT numbers up to 1000 HU, but there was a difference of 3.0% in the higher CT number volume. The difference between the SPR calculated by TPS and the SPR caused by the difference in the energy of the incident particles agreed within 0.51%. The accuracy of SPR estimation was measured, and the error was within 2% for all materials tested. ConclusionThese results indicate that the SPR estimation errors are within the range of errors that can be expected in particle therapy. From commissioning and verification results, the CT-SPR calibration table obtained during this commissioning process is clinically applicable.

Understanding Relative Biological Effectiveness and Clinical Outcome of Prostate Cancer Therapy Using Particle Irradiation: Analysis of Tumor Control Probability With the Modified Microdosimetric Kinetic Model

Purpose: Recent experimental studies and clinical trial results might indicate that - at least for some indications - continued use of the mechanistic model for relative biological effectiveness (RBE) applied at carbon ion therapy facilities in Europe for several decades (LEM-I) may be unwarranted. We present a novel clinical framework for prostate cancer treatment planning and tumor control probability (TCP) prediction based on the modified microdosimetric kinetic model (mMKM) for particle therapy. Methods: Treatment plans of 91 prostate tumor patients (proton: 46, carbon ions: 45) applying 66GyRBE [RBE=1.1 for protons and LEM-I, (α/β)x=2.0Gy, for carbon ions] in 20 fractions were recalculated using mMKM ((α/β)x=3.1Gy). Based solely on the response data of photon-irradiated patient groups stratified according to risk and usage of ADT, we derived parameters for an mMKM-based Poisson-TCP model. Subsequently, new carbon and helium ion plans, adhering to prescribed biological dose criteria, were generated. These were systematically compared to the clinical experience of Japanese centers employing an analogous fractionation scheme and existing proton plans. Results: mMKM predictions suggested significant biological dose deviation between proton and carbon ion arms. Patients irradiated with protons received 3.25±0.08GyRBEmMKM/Fx, while patients treated with carbon ions received 2.51±0.05GyRBEmMKM/Fx. TCP predictions were 86±3% for protons and 52±4% for carbon ions, matching the clinical outcome of 85% and 50%. Newly optimized carbon ion plans, guided by the mMKM/TCP model, effectively replicated clinical data from Japanese centers. Using mMKM, helium ions exhibited similar target coverage as proton and carbon ions and an improved rectum and bladder sparing compared to proton. Conclusions: Our mMKM-based model for prostate cancer treatment planning and TCP prediction was validated against clinical data for proton and carbon ion therapy and its application was extended to helium ion therapy. Based on the data presented in this work, mMKM seems to be a good candidate for clinical biological calculations in carbon ion therapy for prostate cancer.

An investigation of neutron shielding and activation performances of four types of concrete for carbon ion therapy facility

Carbon ions have unique physical and biological properties that allow for precise targeting of tumors while minimizing damage to surrounding healthy tissues. The emitted neutrons dominate the radiation field in the treatment room and pose challenges for radiological shielding. Concrete is extensively utilized in the construction of radiotherapy facilities due to its good shielding characteristics, and it can be easily poured into the desired shapes and thickness. The difference in composition of concrete affects the characteristics of neutron attenuation and activation performance. Therefore, the purpose of this study is to clarify the shielding properties and activation performances of four types of concrete for carbon ion therapy facilities. The Monte Carlo method is used to analyze the neutron spectra from thick targets upon carbon ion bombardment. Furthermore, the deep attenuation efficiency of the secondary neutron in different compositions of concrete is discussed. The shielding design is developed to ensure compliance with the prescribed dose limit outside the shielding during operation. Finally, the induced radioactivity in concrete is estimated for both short-term and long-term operation. The produced radionuclides inventories and depth profiling are determined. This study reveals the shielding and radioactivity issue of carbon ion therapy facilities and is expected to aid in the design or construction of similar facilities.

An international approach to estimating the indications and number of eligible patients for carbon ion radiation therapy (CIRT) in Australia

Background and purposeTo establish the treatment indications and potential patient numbers for carbon ion radiation therapy (CIRT) at the proposed national carbon ion (and proton) therapy facility in the Westmead precinct, New South Wales (NSW), Australia. MethodsAn expert panel was convened, including representatives of four operational and two proposed international carbon ion facilities, as well as NSW-based CIRT stakeholders. They met virtually to consider CIRT available evidence and experience. Information regarding Japanese CIRT was provided pre- and post- the virtual meeting. Published information for South Korea was included in discussions. ResultsThere was jurisdictional variation in the tumours treated by CIRT due to differing incidences of some tumours, referral patterns, differences in decisions regarding which tumours to prioritise, CIRT resources available and funding arrangements. The greatest level of consensus was reached that CIRT in Australia can be justified currently for patients with adenoid cystic carcinomas and mucosal melanomas of the head and neck, hepatocellular cancer and liver metastases, base of skull meningiomas, chordomas and chondrosarcomas. Almost 1400 Australian patients annually meet the consensus-derived indications now. ConclusionA conservative estimate is that 1% of cancer patients in Australia (or 2% of patients recommended for radiation therapy) may preferentially benefit from CIRT for initial therapy of radiation resistant tumours, or to boost persistently active disease after other therapies, or for re-irradiation of recurrent disease. On this basis, one national carbon ion facility with up to four treatment rooms is justified for Australian patients.

Quasi-Alvarez drift-tube linac structures for heavy ion therapy accelerator facilities

Next generation heavy ion therapy and research facilities require efficient accelerating structures. Particularly, at low beam energies, right after the standard scheme of the ion source, low-energy beam transfer, and radio-frequency quadrupole (RFQ), several options for accelerating structures are available including the classic drift-tube linac (DTL), the interdigital H-mode DTL (IH-DTL), and superconducting quarter-wave resonators. These structures need to integrate the beam acceleration with the focusing channel, nowadays typically provided by permanent-magnet quadrupoles (PMQs). The frequency of operation needs to be in line with that of the RFQ structure, and it has been chosen at 750 MHz for practical considerations for the Next Ion Medical Machine Study (NIMMS) that is the application focus of this manuscript. While classic DTL structures at low ion beam energies do not provide enough space for PMQs at that frequency within a single $\ensuremath{\beta}\ensuremath{\lambda}$ period, IH-DTL structures do not provide the regular focusing channel with consequences on the beam quality. For these reasons, quasi-Alvarez drift-tube linac (QA-DTL) structures are reevaluated in this manuscript as they might fill this gap. They have not received much attention in the literature so far and therefore their design is described in detail. The design procedure presented here may serve as a blueprint for DTL design in general. In addition to the overall rf design, axial field stabilization with a new technique and multiphysics studies of the rf structure are described. A cost estimation completes the NIMMS QA-DTL study.

Induced radiation studies and personnel dose assessment in a carbon ion therapy facility

Carbon ions have become the most widely used particles in heavy-ion tumor therapy due to favorable physical and biological characteristics. The beam delivery system (BDS) and tumor tissues are directly bombarded with accelerated carbon ions, resulting in activation products in the components and the patient’s body. The results of an experimental study and a Monte-Carlo simulation for the radioactivity induced in a treatment room under a uniform scanning mode were presented in this study. They indicated that the multi-leaf collimator (MLC) and the patient’s body were the main sources of induced radioactivity. The half-lives of the main produced radionuclides ranged from a few minutes to tens of minutes for single irradiation and from dozens of days to hundreds of days for long-term irradiation. The personal dose of medical staff working in the treatment room and the additional dose of the patient from the induced radioactivity were estimated. Finally, some suggestions were made to reduce the unwanted radiation exposure of the medical staff, patients, and carers.

Flourish of Proton and Carbon Ion Radiotherapy in China.

Proton and heavy ion therapy offer superior relative biological effectiveness (RBE) in the treatment of deep-seated tumors compared with conventional photon radiotherapy due to its Bragg-peak feature of energy deposition in organs. Many proton and carbon ion therapy centers are active all over the world. At present, five particle radiotherapy institutes have been built and are receiving patient in China, mainly including Wanjie Proton Therapy Center (WPTC), Shanghai Proton Heavy Ion Center (SPHIC), Heavy Ion Cancer Treatment Center (HIMM), Chang Gung Memorial Hospital (CGMH), and Ruijin Hospital affiliated with Jiao Tong University. Many cancer patients have benefited from ion therapy, showing unique advantages over surgery and chemotherapy. By the end of 2020, nearly 8,000 patients had been treated with proton, carbon ion or carbon ion combined with proton therapy. So far, there is no systemic review for proton and carbon ion therapy facility and clinical outcome in China. We reviewed the development of proton and heavy ion therapy, as well as providing the representative clinical data and future directions for particle therapy in China. It has important guiding significance for the design and construction of new particle therapy center and patients’ choice of treatment equipment.

Implementation of a rapid response system at an isolated radiotherapy facility through simulation training

A rapid response system is required in a radiotherapy department for patients experiencing a critical event when access to an emergency department is poor due to geographic location and the...

Physical characterization of 3He ion beams for radiotherapy and comparison with 4He

There is increasing interest in using helium ions for radiotherapy, complementary to protons and carbon ions. A large number of patients were treated with 4He ions in the US heavy ion therapy project and novel 4He ion treatment programs are under preparation, for instance in Germany and Japan. 3He ions have been proposed as an alternative to 4He ions because the acceleration of 3He is technically less difficult than 4He. In particular, beam contaminations have been pointed out as a potential safety issue for 4He ion beams. This motivated a series of experiments with 3He ion beams at Gesellschaft für Schwerionenforschung (GSI), Darmstadt. Measured 3He Bragg curves and fragmentation data in water are presented in this work. Those experimental data are compared with FLUKA Monte Carlo simulations. The physical characteristics of 3He ion beams are compared to those of 4He, for which a large set of data became available in recent years from the preparation work at the Heidelberger Ionenstrahl-Therapiezentrum (HIT). The dose distributions (spread out Bragg peaks, lateral profiles) that can be achieved with 3He ions are found to be competitive to 4He dose distributions. The effect of beam contaminations on 4He depth dose distribution is also addressed. It is concluded that 3He ions can be a viable alternative to 4He, especially for future compact therapy accelerator designs and upgrades of existing ion therapy facilities.

Latest developments in in-vivo imaging for proton therapy.

Owing to the favorable physical and biological properties of swift ions in matter, their application to radiation therapy for highly selective cancer treatment is rapidly spreading worldwide. To date, over 90 ion therapy facilities are operational, predominantly with proton beams, and about the same amount is under construction or planning.Over the last decades, considerable developments have been achieved in accelerator technology, beam delivery and medical physics to enhance conformation of the dose delivery to complex shaped tumor volumes, with excellent sparing of surrounding normal tissue and critical organs. Nevertheless, full clinical exploitation of the ion beam advantages is still challenged, especially by uncertainties in the knowledge of the beam range in the actual patient anatomy during the fractionated course of treatment, thus calling for continued multidisciplinary research in this rapidly emerging field.This contribution will review latest developments aiming to image the patient with the same beam quality as for therapy prior to treatment, and to visualize in-vivo the treatment delivery by exploiting irradiation-induced physical emissions, with different level of maturity from proof-of-concept studies in phantoms and first in-silico studies up to clinical testing and initial clinical evaluation.

Developments towards an Advanced Ion Therapy Research Center in the US

The purpose of these developments is to establish an Advanced Ion Therapy Research Center in the US. The proposed center will be the first linac-based ion therapy facility in the world, with the advantage of much desired fast energy and ion beam species switching capability. Such a facility would prove a unique platform to stage the development of pre-clinical studies to prepare for FDA clearance for carbon and other ion beam therapies in the US, and pave the way to establishing clinical ion therapy facilities in this country. The proposed center will enable a breadth of research and applications such as cellular radiobiology, comparative studies of different ion beam therapies and the development of real-time imaging for precise and accurate dose delivery. A multi-institutional collaboration is proposing an innovative center for ion therapy research that will combine an advanced compact carbon ion linac, a compact superconducting carbon beam gantry and real-time MRI-guided beam delivery for therapy. Research and Development towards the realization of the proposed center is underway along three major axes. First, the development of high-gradient accelerating structures for the linac, second, the development of compact curved, combined-function bending magnets and beam scanning magnets for the gantry, and third, the development to combine real-time MRI imaging with ion beam delivery systems. A conceptual design for a compact carbon ion therapy linac has been recently developed. The linac is 45 meters long and capable of accelerating ion beams from proton to neon up to an energy of 450 MeV/u. Prototypes of high-gradient accelerating structures required for the linac are being fabricated and tested. A design of a compact superconducting carbon gantry was also developed and a compact carbon beam scanner magnet is being prototyped. A preliminary concept for MRI-guided ion beam delivery was most recently developed. Other imaging options and range verification techniques, including prompt gamma, positron emission tomography, ionoacoustics and ion beam CT are being considered. Progress made in these areas of development will be presented. Linac-based technology for ion therapy allows more flexibility in beam tuning than synchrotron-based technology with much faster energy modulation and ion beam switching. The reported developments will enable this technology and pave the way to establishing the proposed therapy research center as a national and international resource.

Study of the charge sensing node in the MAPS for therapeutic carbon ion beams

Beam monitoring system in heavy ion therapy facilities ensures the beam energy deposition can accurately cover the dedicated tumour region. For the purpose of building a high-precision beam monitoring system, a Monolithic Active Pixel Sensor (MAPS) is under development. The charge sensing node in the MAPS is formed by an n-well −p− epitaxial layer junction and it collects charge by drift and diffusion. In order to optimize the performance of the charge sensing node, the depletion region, the diode capacitance, the charge collection efficiency and the charge collection time have been studied with TCAD simulations. This paper discusses the simulation results with different bias voltage, node structures and heavy ion hitting locations.

I207] Ion-based imaging and in-vivo range verification in ion beam therapy: Status and perspectives

Swift ions in matter exhibit favorable physical and biological properties, particularly owing to the ability of concentrating their energy deposition at a well-localized depth at their end of range, so-called Bragg peak. Compared to conventional external beam radiotherapy modalities, ion beams thus promise superior tumour-dose conformality and optimal sparing of surrounding critical organs and healthy tissue, with expected benefits for deep-seated, inoperable tumour sites as well as pediatric patients. Hence, interest in this emerging technology has rapidly increased worldwide in the last decade(s). To date, about 70 ion therapy facilities (of which ∼20 in Europe) are operational, predominantly with proton beams, and about the same amount is under construction or planning. Despite considerable recent technological advances, particularly regarding ion accelerators and scanning beam delivery systems, along with integration of in-room volumetric X-ray imaging, full clinical exploitation of the favorable ballistic properties of ion beams is still hampered by the yet unsolved problem of range uncertainties, preventing an exact localization of the Bragg peak (hence dose maximum) in tissue. Although these uncertainties can be mitigated by the introduction of cautious safety margins and careful choice of beam directions, new approaches are being extensively investigated to tackle this issue at the stage of treatment planning or treatment delivery. Here, emphasis will be given to unconventional imaging modalities exploiting energetic ion beams for refined assessment of the tissue stopping properties pre-treatment, as well as to online/post-treatment detection of acoustic and nuclear-based emissions induced by ion interaction in tissue for in vivo verification of the beam range. This contribution will critically review the main ongoing developments and initial pre-clinical or clinical experience, discussing the prospects of unconventional imaging modalities for eventually harnessing the ballistic selectivity of ion beam therapy in the clinical practice.

A silicon strip detector array for energy verification and quality assurance in heavy ion therapy.

The measurement of depth dose profiles for range and energy verification of heavy ion beams is an important aspect of quality assurance procedures for heavy ion therapy facilities. The steep dose gradients in the Bragg peak region of these profiles require the use of detectors with high spatial resolution. The aim of this work is to characterize a one dimensional monolithic silicon detector array called the "serial Dose Magnifying Glass" (sDMG) as an independent ion beam energy and range verification system used for quality assurance conducted for ion beams used in heavy ion therapy. The sDMG detector consists of two linear arrays of 128 silicon sensitive volumes each with an effective size of 2mm × 50μm × 100μm fabricated on a p-type substrate at a pitch of 200 μm along a single axis of detection. The detector was characterized for beam energy and range verification by measuring the response of the detector when irradiated with a 290 MeV/u 12 C ion broad beam incident along the single axis of the detector embedded in a PMMA phantom. The energy of the 12 C ion beam incident on the detector and the residual energy of an ion beam incident on the phantom was determined from the measured Bragg peak position in the sDMG. Ad hoc Monte Carlo simulations of the experimental setup were also performed to give further insight into the detector response. The relative response profiles along the single axis measured with the sDMG detector were found to have good agreement between experiment and simulation with the position of the Bragg peak determined to fall within 0.2 mm or 1.1% of the range in the detector for the two cases. The energy of the beam incident on the detector was found to vary less than 1% between experiment and simulation. The beam energy incident on the phantom was determined to be (280.9 ± 0.8) MeV/u from the experimental and (280.9 ± 0.2) MeV/u from the simulated profiles. These values coincide with the expected energy of 281 MeV/u. The sDMG detector response was studied experimentally and characterized using a Monte Carlo simulation. The sDMG detector was found to accurately determine the 12 C beam energy and is suited for fast energy and range verification quality assurance. It is proposed that the sDMG is also applicable for verification of treatment planning systems that rely on particle range.

Full-beam performances of a PET detector with synchrotron therapeutic proton beams

Treatment quality assessment is a crucial feature for both present and next-generation ion therapy facilities. Several approaches are being explored, based on prompt radiation emission or on PET signals by -decaying isotopes generated by beam interactions with the body.In-beam PET monitoring at synchrotron-based ion therapy facilities has already been performed, either based on inter-spill data only, to avoid the influence of the prompt radiation, or including both in-spill and inter-spill data. However, the PET images either suffer of poor statistics (inter-spill) or are more influenced by the background induced by prompt radiation (in-spill). Both those problems are expected to worsen for accelerators with improved duty cycle where the inter-spill interval is reduced to shorten the treatment time. With the aim of assessing the detector performance and developing techniques for background reduction, a test of an in-beam PET detector prototype was performed at the CNAO synchrotron-based ion therapy facility in full-beam acquisition modality.Data taken with proton beams impinging on PMMA phantoms showed the system acquisition capability and the resulting activity distribution, separately reconstructed for the in-spill and the inter-spill data. The coincidence time resolution for in-spill and inter-spill data shows a good agreement, with a slight deterioration during the spill. The data selection technique allows the identification and rejection of most of the background originated during the beam delivery. The activity range difference between two different proton beam energies (68 and 72 MeV) was measured and found to be in sub-millimeter agreement with the expected result.However, a slightly longer (2 mm) absolute profile length is obtained for in-spill data when compared to inter-spill data.

WE‐H‐BRA‐06: Experimental Investigation of RBE for Lung Cancer Cell Lines as a Function of Dose and LET in Proton, Helium and Carbon Beams

Purpose:Investigate and quantify the effect of dose and LET on the RBE of protons, helium and carbon ions.Methods:High throughput, high accuracy experimental setups were custom designed to investigate the Relative Biological Effectiveness (RBE) dependence on the dose and Linear Energy Transfer (LET) values for proton, helium and carbon ion beams. The experiment was conducted at the HIT facility in collaboration with the DKFZ in Heidelberg/Germany. Clonogenic assays of two human lung cancer cell lines, H460 and H1437, were investigated in this study. γH2AX foci staining on the H460 cell line was also undertaken to facilitate the study of differential DNA double‐strand break induction and repair between low‐design available at the HIT facility. Specific points along the Bragg curve corresponding to well‐defined doses and LET values were chosen by appropriate selection of the pre‐absorber thicknesses. With a setup design for horizontal beam lines we were able to minimize ion scattering in the cell plate, resulting in narrower energy spectra and hence LET distributions in the Bragg peak and in the distal falloff regions, compared to the earlier experiments.Results:Approximately 16,000 samples of cancer cells were irradiated during 23 hours of beam time. The preliminary results of the survival curves for both cell lines show a distinct dependence on LET for a given dose with decreased survival fractions at increasing LET values, encountered at the Bragg peak and in the distal falloff.Conclusion:Our preliminary findings are indicative of the importance of novel variable‐RBE models for proton therapy and provide insight into the RBE of heavy ions for possible future heavy ion therapy facilities in the US.Funding support: SINF 2015/16

Scanning Properties of Dipole Bending Magnets used in Ion-Therapy Gantries

In modern ion-therapy facilities, there is a trend to develop and use scanning beam delivery systems. One of the most important advantages of scanning systems is that the field-shaping material devices in the beam path are minimized or removed entirely. Scanning systems inherently provide the intensity modulated radiation fields of ion beams that allow for a much greater flexibility in tailoring the dose distribution than in the case of passive delivery systems. A study of scanning properties of dipole bending magnets is published in order to provide engineers the theoretical tool for the early stage of a scanning-system design. This study is focused on scanning properties of dipole bending magnets with pure dipole fields without any gradient. The 90°, 60°, 45° and 30° bending magnets are studied. A two-directional magnetic scanning system with two scanners, one in the horizontal and another one in the vertical plane, is considered. This 2D magnetic scanning system ensures a parallel scanning mode in both transverse planes. The ion-optical properties of 2D magnetic scanning system and the study results for dipole bending magnets mentioned above are discussed.

The Development of HITFiL Cyclotron Magnet

A recently constructed cyclotron magnet at the Institute of Modern Physics of Chinese Academy of Sciences (IMPCAS) will be used as the injector of Heavy Ion Therapy Facility in Lanzhou (HITFiL). The diameter of the magnet is 2.92 m and its height is 1.52 m. The total weight of the magnet is 70 tons. The isochronous magnetic field for q/m = 5/12 is achieved by appropriate pole edge profile. The paper discusses the various design and fabrication aspects of the magnet. The paper also presents the field measurement results and its comparison with simulation.