Physical design of scanning gantry for proton therapy facility

A proton therapy facility based on a linac injector and a slow cycling synchrotron is proposed. To achieve effective treatment of cancer, a scanning gantry is required. The flexible transmission of beam and high beam position accuracy are the most basic requirements for a gantry. The designed gantry optics and scanning system are presented. Great efforts are put into studying the sensitivity of the beam position in the isocenter to the element misalignments. It shows that quadrupole shift makes the largest contribution and special attention should be paid to it.     

Irradiation methods and nozzle design for the advanced proton therapy facility

A conception design of the Advanced Proton Therapy Facility (APTF) has been carried out. The system intentionally employs a slow-cycling synchrotron with a maximum energy of 250 MeV, two rotating gantries and two fixed beam nozzles for the treatment. In this paper, we try to compare the strength and weaknesses between the two treatment methods: the beam spreading and the pencil beam scanning. The application of the pencil beam scanning method and the double-scattering method together with the related nozzle design at APTF is also given. The simulation results of employing the double-scattering method have been given during the preliminary design.     

Irradiation methods and nozzle design for the advanced proton therapy facility

A conception design of the Advanced Proton Therapy Facility （APTF） has been carried out. The system intentionally employs a slow-cycling synchrotron with a maximum energy of 250 MeV, two rotating gantries and two fixed beam nozzles for the treatment. In this paper, we try to compare the strength and weaknesses between the two treatment methods： the beam spreading and the pencil beam scanning. The application of the pencil beam scanning method and the double-scattering method together with the related nozzle design at APTF is also given. The simulation results of employing the double-scattering method have been given during the preliminary design.     

ATPF–a dedicated proton therapy facility

A proton therapy facility based on a linac injector and a slow-cycling synchrotron is proposed. To obtain good treatments for different cancer types, both the spot scanning method and the double-scattering method are adopted in the facility, whereas the nozzles include both gantry and fixed beam types. The proton accelerator chain includes a synchrotron of 250 MeV in maximum energy, an injector of 7 MeV consisting of an RFQ and a DTL linac, with a repetition rate of 0.5 Hz. The slow extraction using the third-order resonance and together with the RFKO method is considered to be a good method to obtain a stable and more-or-less homogenous beam spill. To benefit the spot scanning method, the extraction energy can be as many as about 200 between 60 MeV and 230 MeV. A new method – the emittance balancing technique of using a solenoid or a quadrupole rotator is proposed to solve the problem of unequal emittance in the two transverse planes with a beam slowly extracted from a synchrotron. The facility has been designed to keep the potential to be upgraded to include the carbon therapy in the future.     

ATPF—a dedicated proton therapy facility

A proton therapy facility based on a linac injector and a slow-cycling synchrotron is proposed. To obtain good treatments for different cancer types, both the spot scanning method and the double-scattering method are adopted in the facility, whereas the nozzles include both gantry and fixed beam types. The proton accelerator chain includes a synchrotron of 250 MeV in maximum energy, an injector of 7 MeV consisting of an RFQ and a DTL linac, with a repetition rate of 0.5 Hz. The slow extraction using the third-order resonance and together with the RFKO method is considered to be a good method to obtain a stable and more-or-less homogenous beam spill. To benefit the spot scanning 200 between 60 MeV and 230 MeV. A new method method, the extraction energy can be as many as about - the emittance balancing technique of using a solenoid or a quadrupole rotator is proposed to solve the problem of unequal emittance in the two transverse planes with a beam slowly extracted from a synchrotron. The facility has been designed to keep the potential to be upgraded to include the carbon therapy in the future.     

质子治疗装置动态电源控制系统研发

针对质子治疗装置中主环动态电源多平台能量的引出需求,研制了基于开源平台的高速实时动态电源控制系统,该控制系统以开源平台Beaglebone作为顶层硬件接口,以现场可编程逻辑门阵列（FPGA）为核心的控制器作为底层硬件接口,采用分布式的实验物理及工业控制系统（EPICS）进行远程控制。该系统可实时传输任意动态电源的输出参考电流波形数据,并结合定时系统与联锁系统,控制动态电源按预设电流波形进行输出,并实现多平台能量的引出。实验结果显示该控制系统能实现每秒最高十万条指令传输,百万次数据传输零误码率。同时,该系统结构灵活、扩展性强,可作为通用控制平台。     

低能质子束脉冲踢束器的物理设计

电子回旋共振(ECR)质子源产生的脉冲质子束脉宽通常在ms或亚ms量级,高梯度加速结构要求注入的质子束脉宽为100 ns或更短,需要一个脉冲踢束器将大部分不需要的束流踢开,留下所需的短脉冲质子束。设计的踢束器采用静电偏转方法,针对在研ECR质子源的束流参数,设计了脉冲踢束器的结构尺寸,使用ANSYS软件计算了踢束器的静电场分布情况,利用软件内置的CMATRIX宏提取了结构电容的数据,给出了对脉冲踢束电源的参数要求,讨论了踢束脉冲上升沿和产生的束流脉冲上升沿的对应关系。     

Design of a multi-cusp ion source for proton therapy

The permanent magnets of the discharge chamber in a multi-cusp proton source are studied and designed. The three electrode extraction system is adopted and simulated. A method to extract different amounts of current while keeping the beam emittance unchanged is proposed.     

The study on changes of rectum area in proton prostate cancer therapy

The purpose of this study is to determine the changes in the rectum area during treatment and to identify the rectum area within the given field of view in order to reproduce the same pose as that presented during therapy planning to properly deliver the planned dose to the prostate. We obtained digitally reconstructed radiographs after planning treatment for 30 patients out of all patients who had been subjected to proton prostate cancer therapy from August 2012 to November 2014 at this hospital. We then obtained an image using a digital imaging positioning system (DIPS) on the first day of treatment. When planning the digitally reconstructed radiograph treatment, we determined the change in size of the rectum between the actual treatment and treatment planning by measuring the cross section of the rectum and the cross section on the image from the DIPS. The results indicated that the rectum area in the digitally reconstructed radiograph taken during treatment planning and the rectum area obtained from the DIPS image during treatment were different. As a consequence, when region targeted for proton treatment of prostate cancer does not maintain a constant volume, the position of the prostate does not receive an adequate dose due to such changes. Therefore, the results of this study will be useful to determine the corresponding volume during a prostate treatment plan.     

Design of a multi cusp ion source for proton therapy

The permanent magnets of the discharge chamber in a multi-cusp proton source are studied and designed.The three electrode extraction system is adopted and simulated.A method to extract different amounts of current while keeping the beam emittance unchanged is proposed.     

扫描质子微探针质子束刻写

质子束刻写技术利用MeV能量的聚焦质子束对抗蚀剂材料直接刻写m甚至nm尺度微结构。研究了质子束刻写中抗蚀剂胶层样品厚度与涂层机旋转速度的关系以及曝光对抗蚀剂的影响,解决了质子束刻写中抗蚀剂厚胶层样品的制备、固化、显影等技术问题,利用扫描质子微探针系统,在正型抗蚀剂胶层上刻写出m尺度的海宝图形、 双矩形结构,在负型抗蚀剂上刻写出m尺度的平行线条、十字形微结构。     

扫描质子微探针质子束刻写

质子束刻写技术利用MeV能量的聚焦质子束对抗蚀剂材料直接刻写m甚至nm尺度微结构。研究了质子束刻写中抗蚀剂胶层样品厚度与涂层机旋转速度的关系以及曝光对抗蚀剂的影响,解决了质子束刻写中抗蚀剂厚胶层样品的制备、固化、显影等技术问题,利用扫描质子微探针系统,在正型抗蚀剂胶层上刻写出m尺度的海宝图形、 双矩形结构,在负型抗蚀剂上刻写出m尺度的平行线条、十字形微结构。     

医用质子加速器注入器7 MeV漂移管直线加速器的设计

针对质子治癌直线加速器功耗少、长度短的要求,设计了一台工作频率为324 MHz的漂移管型质子直线加速器(DTL)。该DTL把粒子从2.5 MeV加速到7 MeV,功耗为265 kW, 总长1.9 m。横向聚焦采用FODO结构,漂移管内放置永磁铁。提出一种新的束流匹配方案,在射频四极场加速器(RFQ)与DTL之间不设束运线,而是以 DTL入口处的4个单元为匹配段,把RFQ出口处相椭圆匹配到DTL周期结构入口处的相椭圆。 用PARMILA程序对该DTL进行了动力学模拟,结果表明该方案的束流发射度增长很小。     

质子束治疗中非均匀组织的等效水厚度修正研究

非均匀组织等效水厚度修正是研究质子放射治疗的重要组成部分, 利用蒙特卡罗Fluka2011.2程序模拟了不同能量(50–250 MeV)的质子束入射到不同介质中的输运过程, 总结出了在不同介质中质子束初始能量与质子束Bragg峰深度关系, 并拟合出质子束在介质中的等效水厚度修正公式. 结果表明, 对不同能量的质子束入射到非均匀组织中, 通过拟合公式计算出Bragg峰深度值与Fluka模拟的质子束Bragg峰的位置相差在1 mm 之内. 如果建立起介质和水的Bragg峰比与电子密度比关系的数据库, 该公式有可能用于临床上的质子放射治疗的剂量计算中. 关键词： 蒙特卡罗 质子治疗 等效水厚度 Bragg 峰     

重离子治癌装置研究

介绍了重离子治癌装置的最新发展状况 ,比较了两类典型的旋转机架的结构及光学特性 ,给出了离子光学的限制条件 .设计了一台桶形机架 ,为兰州重离子冷却储存环应用于医学治疗进行了预研. A simple plane rotating gantry is proposed at the Heavy Ion Research Facility in Lanzhou (HIRFL), where a new project named Cooling Storage Ring is under construction. The gantry is 18 metre long, 5 metre high from upper beam axes to rotation axes. It consists of eight quadruples, two 45° and one large aperture 90° dipole magnets. It is equipped with a two direction magnetic raster scanning system. A beam spot of radii between 2 to 5 mm can be achieved at∶...     

Individual patient shielding for a proton eye therapy facility

The first proton ocular radiotherapy facility in Poland has been developed at the Institute of Nuclear Physics (IFJ PAN), Kraków, in collaboration with the Clinic of Ophthalmology and Ocular Oncology of the Collegium Medicum of the Jagiellonian University in Kraków and the Centre of Oncology of the Maria Sk?odowska–Curie Memorial Institute Kraków Branch. For the proton beam from the AIC-144 isochronous cyclotron the unwanted patient dose due to secondary radiation - predominantly neutrons - has been evaluated using the MCNPX code. Optimisation of the beam forming elements and designing of the additional patient shielding has been performed to minimize the unwanted patient’s dose.     

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。     

扫描透射离子显微成像系统的建立和实验研究

 基于上海应用物理研究所的扫描质子微探针系统,对扫描透射离子显微成像（STIM）技术进行了仿真分析和实验研究,建立了基于中值滤波方法的数据处理程序,获得了大鼠股骨切片的面密度分布和薄壁小球的离轴STIM图像。理论分析和实验结果显示：由在轴探测数据的中值滤波结果可以计算出定量的面密度分布信息,由能量窗滤波的离轴探测数据则可以给出高分辨的定性图像,这在薄样品、强束流、以及质子激发X荧光（PIXE）分析同时进行的STIM分析中尤为有用;增加获取的事件数、选择合适的滤波方法可以使测量误差远小于阻止本领计算带来的误差。该方法可以用于测量几十μm尺度样品的绝对质量以及辅助PIXE技术进行元素定量分布分析。     

A design study of a magnifying magnetic lens for proton radiography

Magnifying magnetic lenses can be used in high-energy proton microscopes. The -I lens suggested by Zumbro is analyzed in this paper, and a new type of magnetic lens called a lengthened lens is introduced. Theoretical analysis shows that the lengthened lens can form a magnifying lens, and at the same time the main advantages of a Zumbro lens are inherited. Using the My-BOC beam dynamics code, an example of the design is shown. The results show that the method of designing magnifying magnetic lenses is effective.     

重离子治疗肿瘤点扫描控制系统

为了实现重离子治疗肿瘤点扫描,对扫描磁铁进行相应的控制。治疗计划进行剂量与肿瘤适形数据的生成,并传输至点扫描控制器与剂量控制器。同时也向点扫描控制器中存入事例数据,以纳入整个加速器控制时序,等待同步时间事例系统的事例触发。点扫描控制器根据剂量控制器的脉冲控制换点治疗操作以及进行换点治疗的扫描磁铁插值算法平滑处理。剂量控制器对气体电离室前端电子学已经刻度的剂量脉冲进行计数。当达到治疗剂量时,控制法拉第筒来阻挡束流,实现点扫描安全治疗。实验证明在现有的电源与磁铁等设备条件以及束流品质下,点扫描控制系统能实现2 mm点间距扫描。