适用于适形治疗与调强治疗的质子束流配送系统

描述一个适用于适形治疗和调强治疗的散射式质子束流配送系统.它利用双散射系统扩展质子束,利用程序控制的二进制射程调节器和搓板式调制器调节和调制质子射程,利用程序控制的多叶光阑和为每个患者特制的准直器进行束流准直.     

Development of dosimetry tools for proton therapy research

Dosimetry tools for proton therapy research have been developed to measure the properties of a therapeutic proton beam. A CCD camera–scintillation screen system, which can verify the 2D dose distribution of a scanning beam and can be used for proton radiography, was developed. Also developed were a large area parallel-plate ionization chamber and a multi-layer Faraday cup to monitor the beam current and to measure the beam energy, respectively. To investigate the feasibility of locating the distal dose falloff in real time during patient treatment, a prompt gamma measuring system composed of multi-layer shielding structures was then devised. The system worked well for a pristine proton beam. However, correlation between the distal dose falloff and the prompt gamma distribution was blurred by neutron background for a therapy beam formed by scattering method. We have also worked on the design of a Compton camera to image the 2D distribution of prompt gamma rays.     

Trends in accelerator technology for hadron therapy

Hadron therapy with protons and carbon ions is one of the most effective branches in radiation oncology. It has advantages over therapy using gamma radiation and electron beams. Fifty thousand patients a year need such treatment in Russia. A review of the main modern trends in the development of accelerators for therapy and treatment techniques concerned with respiratory gated irradiation and scanning with the intensity modulated pencil beams is given. The main stages of formation, time structure, and the main parameters of the beams used in proton therapy, as well as the requirements for medicine accelerators, are considered. The main results of testing with the beam of the C235-V3 cyclotron for the first Russian specialized hospital proton therapy center in Dimitrovgrad are presented. The use of superconducting accelerators and gantry systems for hadron therapy is considered.     

软调制双散射质子治疗束流配送系统

质子治疗是一种新兴的放射治疗方法,它的主要优点是剂量分布特性优良,可以使高辐射剂量集中于肿瘤部位,减少对周围正常组织的损伤.这一优点的实现主要依靠束流配送系统,它包含质子能量调节与调制、束流扩展和准直等功能.现提出一种新的软调制双散射质子治疗束流配送系统.其特点是利用程序控制质子能量变化以改变质子在体内的射程从而展宽Bragg峰,同时利用两次散射获得较大面积的均匀照射野.它的优点是运行可靠、调节灵活,并特别有利于实现适形治疗.     

蒙特卡罗模拟单阻止柱双散射体质子束流扩展方法

束流扩展是研究质子治疗大体积深度肿瘤的基础,利用Monte Carlo多粒子模拟软件Fluka2006.3b.10,计算质子经过单阻止柱双散射体后束流横向分布特性,与相同条件下由Highland公式经解析计算相比较.结果表明:在束流分布均匀性大于95%的范围内,Fluka计算得到的质子通量小于由Highland公式经解析计算得到的结果,膜薄的条件下二者符合好于膜厚的条件.束流扩展半径随着两个散射膜厚度的增加而增大,束流利用率先增加后减小,最大值是16.9%.     

100 MeV质子束流品质诊断及剂量测量准确性评估方法研究

质子辐射生物学效应是太空放射生物学和质子束放疗研究的重要基础,可为空间环境下人员的危险性评估以及质子治疗优化设计提供科学依据。依托加速器建立相应的生物样本辐照技术是开展此类研究的前提条件。中国原子能科学研究院最近建立的100 MeV强流质子回旋加速器提供的中能质子束流为目前国内能量最高,特别适合用于太空放射生物学和质子治疗相关研究。本研究中,利用在束和离线等多种手段建立了中能质子束流诊断和剂量测量方法,对加速器引出的100 MeV质子照射野大小、均匀性等束流品质以及剂量测量系统准确性进行了分析和评估。结果表明,对光子剂量响应好的LiF(Mg, Ti)热释光探测器,对90 MeV质子同样具有良好的剂量响应关系,可作为中能质子剂量准确性评估的手段之一。在5.0 cm×5.0 cm照射野范围内,加速器引出的100 MeV质子束流的均匀性好于90%,在线剂量测量系统准确性好于93%,束流品质和剂量测量条件基本满足辐射生物学的要求,可为质子辐射生物学效应研究的开展提供可靠保障。     

国产首台交变相位聚焦漂移管加速器的冷测与试运行

质子直线注入器是质子治癌系统的重要组成部分。出于项目进度的考虑,上海先进质子治癌示范装置APTRON采用了进口自美国的直线注入器。为了加快质子治癌产业进程,掌握质子放疗关键技术,保证产业链安全可控,注入器团队研发了国产医用质子直线注入器。该直线注入器采用了电子回旋共振（ECR）离子源和四翼型射频四极加速器（RFQ）的技术方案,并在漂移管加速器（DTL）段创新性地采用了交变相位聚焦（APF）结构。在这个过程中,通过研究APF DTL的束流运动规律和设计思想,自主开发了APF DTL的底层物理设计软件,相继完成了物理设计、电磁设计、机械设计、加工建造、腔体冷测、高频老练和载束实验等多个阶段的工作,最终成功引出了7 MeV、7 mA的质子束流。经过束诊系统的测量分析,认定束流中心能量为6.975 MeV,动量分散在±0.35%以内的束流流强为6.07 mA。成为国产首台医用质子直线注入器和首个实现成功载束的APF加速腔。     

A system for proton beam control during radiotherapy

A system for the on-line control of proton beam profiles and track has been designed and constructed to guarantee the quality assurance of radiotherapy carried out in the Medical-Technical Complex of the Joint Institute for Nuclear Research. To measure the horizontal and vertical profiles of the beam in the treatment room, a multiwire ionization chamber has been designed and constructed. The chamber consists of two anode and three cathode electrodes. Each anode electrode contains 30 wires 0.1 mm in diameter separated by 3 mm. To control the beam track, four industrial semiconductor diodes 2D212A designed for radio engineering application were used. The system is installed in front of the first collimator in the peripheral part of the beam, so that it does not disturb the operated part of the beam. Output signals from the ionization chamber and the diodes are processed by a specially constructed electronic device connected to a personal computer. It utilizes 64-channel 16-bit charge-current converters (TERA chip). One-years’s experience of the operation of the system in proton therapy treatment sessions has shown its high reliability and sensitivity to proton beam parameters. The accuracy of controlling the asymmetry of the beam profiles is 2% and the track deviations are equivalent to 0.2 mm of water.     

基于磁场调制的质子放疗新方法及其调制机制

提出一种基于磁场调制的质子放射治疗新方法, 探索肿瘤剂量、正常器官剂量与磁场调制方法之间的关联机制, 研究磁场调制质子放疗在器官环绕型肿瘤(肿瘤被正常器官环绕或包围)治疗中的应用。基于蒙特卡罗粒子输运程序Geant4,分别建立了理想器官环绕结构（由若干平行六面体结构组成）和含胰腺肿瘤人体腹部解剖结构两种几何构型。分别对两种几何构型内部施加磁场, 通过改变磁场强度和方向,调制质子束布拉格峰几何位置, 利用质子径迹的磁致偏转效应使质子束绕开正常器官对肿瘤进行照射。 对于理想器官环绕型构型, 磁场调制质子放疗可在保证95%剂量覆盖肿瘤情况下将受质子照射正常器官体积控制在接近于零的极低水平。对于胰腺肿瘤解剖构型, 磁场调制方法可使质子束在调制磁场作用下, 绕过脊髓和肾脏照射肿瘤, 并使肿瘤被95%剂量较好地覆盖。通过磁场调制, 可对质子束布拉格峰几何位置和质子径迹弯曲程度进行调制, 绕过正常器官对肿瘤进行照射,从而最大限度地减少正常器官的受照体积和剂量。     

治癌离子同步加速器的物理设计

根据国际放射疗法的现状和发展, 为了进一步提升国内的肿瘤放射疗法, 研究设计了1台由两个完全相同的超周期组成的治癌专用离子同步加速器, 包括LATTICE、多圈注入系统、RF加速及三阶共振慢引出系统. 该加速器可以把质子加速到250MeV及碳离子加速到400MeV/u.     

Development of a laser-driven proton accelerator for cancer therapy

Recent advances in laser technology have made proton (light ion) acceleration possible using laser-induced plasmas. In this work, we report our work for the last few years on the investigation of a new proton therapy system for radiation oncology, which employs laser-accelerated protons. If successfully developed, the new system will be compact, cost-effective, and capable of delivering energy-and intensity-modulated proton therapy (EIMPT). We have focused our research on three major aspects: (1) target design for laser-proton acceleration, (2) system design for particle/energy selection and beam collimation, and (3) dosimetric studies on the use of laser-accelerated protons for cancer therapy. We have performed particle-in-cell (PIC) simulations to investigate optimal target configurations for proton/ion acceleration. We also performed Monte Carlo simulations to study the beam characteristics and the feasibility of using such beams for cancer treatment. Since laser-accelerated protons have broad energy and angular distributions, which are not suitable for radiotherapy applications directly, we have designed a compact particle selection and beam collimating system for EIMPT beam delivery. We also proposed a new gantry design to make the whole system compact to retrofit existing linac vaults. We have compared Monte Carlo calculated dose distributions using X-ray IMRT and laser-proton EIMPT. Our results show that EIMPT using laser protons produces superior target coverage and much reduced critical structure dose and integral dose compared to X-ray IMRT.     

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

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

APTR质子同步加速器RFQ直线注入器的优化设计

为实现质子治疗装置的国产化和小型化,基于已完成安装调试的上海先进质子治疗装置(APTR),开展质子治疗注入器系统的升级设计研究,利用PARMTEQM设计软件和快聚束策略,针对APTR同步加速器RFQ直线注入器进行动力学设计模拟。RFQ工作频率为325 MHz,流强18 mA,对从离子源引出的低能质子束流进行匹配俘获、横向聚焦、纵向聚束和预加速,引出能量为3.0 MeV。通过优化预注入器RFQ动力学设计方案和极头参数,有效避免参数共振,减小束流损失,使其整体传输效率达到98.0%,在水平和垂直方向上的发射度增长分别为1.2%和3.3%,出口束流满足下一级腔体的注入需求,开展设计模拟验证和相关冗余度分析,为质子同步加速器的治疗设备和直线注入系统提供参照依据。     

Investigation of chromosome damage in human cells irradiated by beam for proton therapy produced by phasotron at the joint institute for nuclear research

The physical characteristics of the proton beam produced by a phasotron at JINR for radiation therapy are given. Chromosome damage in cells on the model of human blood lymphocytes irradiated by the initial proton beam with an energy of 170 MeV at the entrance to the object and in the Bragg peak region is studied, which corresponds to the irradiation of surrounding tissues along the beam path and tumor tissues. High proton efficiency in the Bragg peak is shown. RBE in the Bragg peak is ～1.25 in the dose range 1–4 Gy, while the proton efficiency of the initial beam is the same as that of standard γ radiation. Since delivering a dose to a tumor is performed by irradiating the patient from several directions (up to 7), the level of cytogenetic damage to cells of the surrounding tissues on the path of the initial beam is reduced by approximately an order of magnitude. Thus, for a dose of 3 Gy in a tumor, up to 80% of its cells are damaged, while the level of damage in the surrounding tissues does not exceed 10%. The results of investigations confirm the high efficiency of proton beams for radiation therapy.     

Design study for a 500 MeV proton synchrotron with CSNS linac as an injector

Using the China Spallation Neutron Source(CSNS) linac as the injector, a 500 MeV proton synchrotron is proposed for multidisciplinary applications, such as biology, material science and proton therapy. The synchrotron will deliver proton beam with energy from 80 MeV to 500 MeV. A compact lattice design has been worked out, and all the important beam dynamics issues have been investigated. The 80 MeV H-beam is stripped and injected into the synchrotron by using multi-turn injection. In order to continuously extraction the proton with small beam loss,an achromatic structure is proposed and a slow extraction method with RF knock-out is adopted and optimized.     

A Proton Beam Delivery System Variant for the Oncological Ophthalmological Center for Proton Radiation Therapy at the NRC “Kurchatov Institute”—PNPI

Physics of Atomic Nuclei - A variant of the proton beam delivery system with an energy of 60 MeV for the future oncological ophthalmological center for proton radiation therapy at the isochronous...     

医用质子直线加速器的设计研究

讨论用于治癌的低束流高能量质子直线加速器的初步物理设计.采用短脉冲和高重复频率的S波段的加速结构,类似于医用电子直线加速器.总长26m,由离子源、RFQ、DTL、SCDTL及SCL组成,能量经70—200MeV有八档可调,平均束流强度10—40nA.     

粒子束团状态对测量束流发射度及能量的影响

为了验证国产质子注入器的参数是否满足需求,注入器团队设计了束流测量系统用于测量国产质子直线注入器束流的流强、发射度、能量以及能散等关键指标。此测量系统包含了采用变聚焦法测量发散度、采用分析磁铁测量束流能量和能散的主要功能。利用束流输运线设计软件Tracewin(版本2.11.4.1)进行了系统束线的物理设计,对束测系统测量质子束流的发散度和能量的精度进行了模拟计算。由于经过RFQ-(APF)DTL加速后的粒子束团为“拖尾”的非理想粒子束团,需要针对非理想束团对束测系统测量发射度和能量产生的影响进行分析。通过对模拟计算结果的分析,发现相对于测量理想粒子束团的结果非理想粒子束团对束测系统测量发射度精度影响较大;非理想粒子束团对束测系统测量能量精度影响较小。     

A new approach to produce spread-out Bragg peak using the MINUIT fit

A new approach to obtain a spread-out Bragg peak (SOBP) using the MINUIT fit is presented. The SOBP has been adopted in proton therapy in order to irradiate a proton beam equally over the tumor along the beam direction. In principle, an SOBP can be easily obtained by using several Bragg peaks from different beam energies, since the position of the peak varies with the energy. However, this is not practical in real medical situations, because the beam energy is fixed by the accelerator. Thus, a modulation method has been employed to obtain an SOBP, where the position of Bragg peak is controlled by a modulator with varying thickness. In this study, we use the GEANT4 package to simulate a generic proton therapy apparatus. A modulator with thickness control is assumed in the proton therapy setup and a set of Bragg peaks is obtained from the GEANT4 simulation. Assuming that the position and the size of the tumor are known, we first determine which Bragg peaks should be used in the fit. Then a MINUIT fit is applied to calculate the weights of each Bragg peak in order to maximize the flatness of the SOBP while minimizing the dose in the normal tissue area, thus maximizing the dose in the tumor. The fit has turned out to be very robust and converges quickly. Since the MINUIT is a small size library and the proposed SOBP fit shows stable behavior, this method can be readily applied to the real therapy.     

Simulation of beam extraction from C235 cyclotron for proton therapy

The extraction of an accelerated beam from C235 cyclotron (IBA, Belgium) for proton therapy is simulated. The results of optimizing the parameters of the extraction system to increase the beam extraction efficiency are presented. Our theoretical results agree well with the experimental data. A new configuration of electrostatic deflector is proposed based on the numerical results; using this configuration essentially increases the efficiency of the cyclotron extraction system.