HIRFL浅层肿瘤重离子治疗终端束流配送系统性能的实验验证

详细介绍了兰州重离子研究装置(HIRFL)浅层肿瘤重离子治疗终端的被动式束流配送系统, 对该束流配送系统重要组成部件及其整体的性能进行了实验验证. Bragg峰展宽装置脊形过滤器及能量调节装置射程移位器测试结果显示该设备的性能指标达到设计要求. 为验证该被动式束流配送系统的整体性能, 进行了束流成形实验, 模拟对肿瘤靶区的三维适形照射. 结果表明: 利用该束流配送系统可实施对肿瘤的三维适形放射治疗. HIRFL浅层肿瘤治疗装置束流配送系统性能的验证为下一步开展肿瘤重离子束治疗临床试验奠定了基础.     

HIRFL辐照终端照射野均匀度与离子通量的关系

采用固体核径迹探测器聚碳酸脂膜,测定了兰州重离子研究装置提供的55MeV/u40Ar和80MeV/u20Ne离子束经辐照终端束流均匀化扫描装置后照射野均匀度与离子通量之间的关系.结果表明:对于40Ar和20Ne离子束,离子通量小于1×106和2×107ions/cm2时,横向照射野均匀度缓Ne离子束照射慢增加;当离子通量分别介于1×106—1×107和2×107—1×108ions/cm2时,40Ar和20野均匀度逐渐增加;离子通量达到1×107和1×108ions/cm2时,40Ar和20Ne离子束照射野均匀度分别约为58%和61%.从而说明,辐照终端束流扫描装置对束流的均匀化程度目前并不能满足辐照生物效应、辐射育种和重离子治癌等研究工作的需要,须对其性能做进一步的提高. Using 55 MeV/u 40Ar and 80 MeV/u20Ne ion beams delivered by the Heavy Ion Research Facility at Lanzhou (HIRFL), the relationships between the irradiation homogeneities in irradiation fields generated by the beam scanning device located at the irradiation terminal of the HIRFL and ion fluence were measured respectively with 100 μm polycarbonate films by means of nuclear track detection. The results show that the homogeneity increases when the ion fluence are lower than ........     

重离子加速器示范装置被动式束流配送系统次级中子特征的蒙特卡罗研究

在碳离子放射治疗中,碳离子束在剂量配送过程中会与束流输运线相互作用,形成以中子辐射为主的外辐射场.由于中子是高LET射线,具有较高的相对生物学效应,减少碳离子放疗中产生的次级中子有助于降低放疗后正常组织并发症几率及二次肿瘤风险.利用蒙特卡罗方法对保守情况(能量为400 MeV/u,多叶光栅完全闭合)下碳离子治疗被动式束...     

用于浅层肿瘤重离子治疗的终端束流诊断控制系统

 设计了中国科学院近代物理研究所利用兰州重离子研究装置（HIRFL）进行浅层肿瘤临床治疗试验研究中所使用的束流诊断安全控制系统。该系统包括束流强度监测及保护、剂量测量、扫描波形监测及保护3个部分。系统基于PXI系统及LabVIEW软件,给出了该系统的各部分结构。从系统建立时的多次测试结果以及实际临床治疗试验研究时的长期运行结果来看,该束流诊断控制系统在控制辐照剂量以及安全保护方面能够满足当前重离子加速器浅层肿瘤临床治疗试验的基本要求,为试验研究的顺利进行提供了可靠的保证。     

基于TPS和蒙特卡罗计算的12C肿瘤放射治疗In-beam PET剂量监测研究

In-beam PET成像是碳离子放射治疗剂量监测的有效手段,可以对碳离子放疗过程的物理剂量分布和生物剂量分布进行实时监测。结合放射治疗计划系统(TPS)和蒙特卡罗(MC)模拟分别对静态均匀水模体和腹部肿瘤CT图像进行治疗计划设计、MC计算和PET成像,比较TPS肿瘤靶区剂量分布、MC模拟剂量分布和PET成像三者之间的一致性。TPS和MC模拟中相对生物学效应(RBE)的计算均采用线性二次模型(LQ)。研究结果显示,TPS和MC计算的静态均匀水模体、单野治疗腹部肿瘤的物理剂量、RBE加权剂量在SOBP区域的平均误差均在0.5%和2%以内。碳离子束流能量为120~400 MeV/u时,束流方向剂量深度分布与PET成像在SOBP区域的位置差异均在8 mm以内。In-beam PET可作为碳离子放射治疗中位置验证和剂量验证的有效手段。     

重离子Bragg峰的研究及其应用

实验测定了由HIRFL引出的25、30MeV/u ⁴⁰Ar,离子经不同厚度降能片后的相对电离(Bragg曲线),并将实验结果同TRIM88程序的计算结果进行了比较,发现⁴⁰Ar离子贯穿深度较浅时,实验结果与程序计算符合很好. 并对中能重离子在水中贯穿深度与相对电离关系的计算,提出了一种对浅层且体积不大肿瘤的重离子治疗方案.     

丰中子核8He在Si靶上的反应总截面的测量

利用HIRFL 50MeV/u ¹³C束流在Be靶上碎裂,RIBLL选择出丰中子放射性次级束流⁸He,实验测量了25—40MeV/u ⁸He在²⁸Si靶上的反应总截面.采用双参数HO密度分布形式,通过微观Glauber模型拟合⁸He实验数据,发现⁸He具有扩展的中子密度分布.实验结果与Warner反应总截面实验和Alkhazov弹性散射实验结果较好地符合.     

CSR的辐射防护

CSR(cooling storage ring)按计划将于2005年底建成调束,届时从¹²C到²³⁸U的重离子将可以分别被加速到900和400MeV的能量. HIRFL(兰州重离子加速器Heavy Ion Research Facility in Lanzhou)将 用作CSR的注入器. 为了CSR的屏蔽设计,本文利用现有的实验数据计算了由于束流损失产生的中子及其能谱、角分布,同时也估算了屏蔽体外表面的中子剂量、环境中子剂量及天空返照中子剂量. 在源项计算中使用了400MeV/u ¹²C+Cu反应的中子产额、能谱、角分布的实验数据. 计算表明, CSR对环境剂量影响最大的是天空返照中子.     

重离子束治癌中深度剂量分布优化

针对兰州重离子研究装置所加速的120MeV/u ¹²C离子束,利用模拟退火优化算法进行了Bragg峰展宽的剂量优化.取相同的展宽区域(30mm),4种不同的步长(2,1,0.5,0.25mm)进行Bragg峰展宽模拟.对所得到的剂量平均值,均方差,入射口剂量,峰坪比等优化结果的参数做了比较.讨论了重离子束治癌临床上最优的Bragg峰展宽模型的选取.     

碳离子束射程快速验证方法的蒙特卡罗模拟研究

可通过楔形装置把离子束(质子和重离子)纵向上的的深度剂量分布转换成横向上的剂量分布,进行离子束射程的快速测量及验证。本工作通过基于GEANT4内核的GATE蒙特卡罗模拟平台,模拟计算了不同能量碳离子束在用于制作楔形装置的铜、铝、铁和有机玻璃等材料中的深度剂量分布,得到不同能量碳离子束在不同材料中Bragg峰位所处深度与能量之间的关系;模拟计算了不同能量碳离子束穿越单楔板、双楔板和大小组合楔板等楔形装置后横向上的剂量分布,得到了横向剂量峰值出现位置与碳离子束射程之间的关系。本文蒙特卡罗模拟研究为进一步开发重离子治疗当中的射程快速验证方法与设备奠定了坚实的基础。     

几种超弹性多次碰撞的讨论

本文分析了几种超弹性碰撞多次连续碰撞的过程，以期对照弹性碰撞的进一步理解．实现这些物理过程对物理教学是相当有趣的．     

Coupling Between Spin and Gravitational Field and Equation of Motion of Spin

In general relativity, the equation of motion of the spin is given by the equation of parallel transport, which is a result of the space-time geometry. Any result of the space-time geometry cannot be directly applied to gauge theory of gravity. In gauge theory of gravity, based on the viewpoint of the coupling between the spin and gravitational field,an equation of motion of the spin is deduced. In the post Newtonian approximation, it is proved that this equation gives the same result as that of the equation of parallel transport. So, in the post Newtonian approximation, gauge theory of gravity gives out the same prediction on the precession of orbiting gyroscope as that of general relativity.     

稀土发光和光谱理论的研究进展

简述了近20多年以来我们在稀土发光和光谱理论方面所做的主要工作、取得的进展和成果。包括:(1)关于(4f)^N组态内单光子跃迁强度:推广Judd-Ofelt三参量公式,在其中计入"J混合"(偶宇称晶场成分造成的)导致的修正;澄清了国际上关于Judd-Ofelt全参量公式中"静力学项"和"动力学项"相对正负号的争论(仍为负号)。(2)关于(4f)^N组态内双光子过程强度:提出直接计算强度方法(放弃缔合近似,利用Ce³⁺的5d和左邻RE³⁺的(4f)^N能级-波函资料,近似模拟出最重要的虚中间组态(4f)^N-15d的能级-波函结构)来讨论和改进Judd-Ofelt缔合近似。(3)固体中声子辅助的稀土离子间能量传输理论:发现HLO理论关于单声子过程中的"干涉相消"实际只适合于对角过程,而非对角过程则是"干涉相加",因而,后者首要的是单声子而非双声子过程;同时,用"晶体格波模"取代"Debye模"描述能量传输中的声子,给出了新模型下计算对角和非对角过程速率等物理量的整套公式。并由之看出:波矢q=0和对应色散曲线扁平段的光学声子对单声子非对角过程速率有完全不能忽略的贡献,这些都不同于或超出于HLO理论。(4)提出和发展了分析指认4f-5d跃迁光谱的简单理论模型,用能量和跃迁强度同时进行近似拟合,成功地分析指认了从(4f)³到(4f)¹³离子在几种基质中的4f→5d吸收(激发)谱,也成功用于若干5d→4f辐射谱。(5)对跃迁的初末晶场态同时引用有效自旋哈密顿描述稀土离子间超交换作用,成功地解释了低温10 K时立方结构的纯稀土冰晶石晶体Cs₂NaLnCl₆(Ln=Er,Yb)等的吸收谱中0声子线(量级为几个cm^-1)的精细分裂。     

迈克尔逊干涉仪实验中的三个问题

本文对在大学物理实验迈克尔逊干涉仪调节和使用题目中被教师忽略却常被学生提出的三个问题进行了细致分析和讨论，并给出了解决建议。     

Luminescence of silver chloride microcrystals upon photoexcitation by different methods

The luminescence spectra of AgCl microcrystals were measured in two different regimes: in the regime of excitation of stationary luminescence and in the regime of photostimulated burst of luminescence. Differences between the spectra of stationary luminescence and the spectra of photostimulated-luminescence burst in the range between 430 and 590 nm have been found. The luminescence spectra are complex; the ratio of intensities for elementary components changes with the technique of excitation. Differences in the form and composition of complex luminescence bands obtained under different conditions of registration are attributed to the recombination interaction of the luminescence centers. It is shown that analysis of the dependences of intensity ratios for the elementary components of a complex luminescence band on the exciting-radiation intensity allows one to evaluate the mechanism of recombination in elementary bands provided that the mechanism is known for at least one luminescence band.__________Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 1, pp. 85–89. January–February, 2005.     

The Antikythera mechanism and the mechanical universe

Astronomers have two approaches to trying to determine the age of the Universe. They can estimate the ages of individual objects in the Universe and specifically in our Galaxy. These estimates use either the observed properties of stars and theoretical ideas concerning stellar evolution or the abundances of long-lived radioactive isotopes and their decay products. Alternatively they can use cosmological theories and observations to try to determine the age of the entire Universe. Obviously the Universe must be older than its component parts but neither of the above methods is sufficiently reliable that this is true of the deduced ages. As a result, it is from time to time reported that some object in the Universe is older than the Universe itself. In this article we discuss the methods that are currently being used to determine the age and we emphasize the problems in obtaining reliable results. It is not at present possible to provide a definite value for the age of the Universe.     

对质点系角动量定理的讨论

对理论力学教材中角动量定理的各种不同表达式进行了归纳、比较、讨论、明确了它们之间的区别、联系及其适用条件。     

First approximation to the Hugoniot equation of state of the lanthanides

Summary The semi-empirical Hugoniot equation of state is obtained by using the third-order tangency between the isentropic and the Hugoniot curves at the origin of coordinates. The results of this model are in good agreement with Carter’s experimental data for fourteen elements from the lanthanides series in the lower phase only. Due to postal troubles with Lebanon, it was impossible to send proffs to the author as he requested.     

正态分布随机数发生器及其在模拟光传输软件中的应用

 利用计算机高级语言提供的伪随机数发生器,通过“高斯筛选”和“求平均值”两种方法,开发出满足正态分布的随机数发生器。将其应用于分析大型激光装置光路稳定性的模拟软件中,成功地完成了对“神光Ⅲ原型装置四程放大器”的光路稳定性分析。     

Coupling Between Spin and Gravitational Field and Equation of Motion of Spin

In general relativity, the equation of motion of the spin is given by the equation of parallel transport, which is a result of the space-time geometry. Any result of the space-time geometry cannog be directly applied to gauge theory of gravity. In gauge theory of gravity, based on the viewpoint of the coupling between the spin and gravitational field, an equation of motlon of the spin is deduced. In the post Newtonian approximation, it is proved that this equation gives the same result as that of the equation of parallel transport. So, in the post Newtonian approximation, gauge theory of gravity gives out the same prediction on the precession of orbiting gyroscope as that of general relativity.