共查询到19条相似文献,搜索用时 78 毫秒
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肿瘤治疗的重离子束物理性质研究 总被引:2,自引:0,他引:2
重离子在肿瘤治疗方面的优势主要是由于其优越的物理性质,因此,研究其与生物体相互作用也就成为肿瘤治疗中的基本课题,介绍一些研究结果来解决人们关心的问题.The advance of tumor therapy with heavy ions beam is due to the physics quality of heavy ions.So,the investigation of heavy ions action with biological materials will be a basic task. In the paper, the investigated results show a picture to resolve some problems which attract people's attention. 相似文献
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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 相似文献
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12C离子束的剂量学研究 总被引:1,自引:0,他引:1
研究了L-α-丙氨酸剂量计测量^12C离子辐射的剂量学特性,实验证明丙氨酸剂量计适用于^12C离子辐射的剂量学测量。另外,还研究了^12C离子照射人外周血诱发的染色体畸变(双着丝粒+着丝粒环)的剂量效应,在0-8.0Gy范围内拟合的最佳回归方程为Y=0.858503D+0.3615×10^-2D^2。Dosimetric characteristics of L-α-alanine dosemeter used for dosimetry of ^12C ion radiation have been studied. The experimental results indicate that the alanine dosemeter can be used to measure the ^12C ion radiation. In addition, dose effects of chromosome aberration dicentrics and cenric rings were studied after human peripheral blood being irradiated by ^12C ions; the best regression equation, Y = 0. 858 503D + 0. 361 5 ×10^-2D^2, was obtained within 8.0 Gy. 相似文献
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C离子束放射治疗肿瘤的进展 总被引:2,自引:1,他引:2
重离子(C离子)用于肿瘤放射治疗具有物理学和生物学两方面的优势, 被誉为面向21世纪最佳放疗用射线。 综合论述了世界各国重离子束治癌的发展历史, 在日本国立放射医学综合研究所(NIRS)提供的临床试验数据基础上分析了C离子束治疗的适应症以及对正常组织的放射损伤。 此外, 通过分析潜在患者人数和治疗相关硬件与软件设备, 对C离子束治癌的运用前景做了初步评估。Heavy ions (carbon ions) were considered currently as the best radiation in radiotherapy for their two superiorities in the physical and biological properties. This paper firstly put the focus on the history of development of heavy ion radiotherapy in the world, then a comprehensive analysis of the indications and radiation damages of normal tissues in clinical trails of heavy ion therapy was made based on the published data by NIRS. Moreover, the prospect of using carbon ions in radiotherapy was estimated by analyzing the potential patients’ number, its related instruments and etc. 相似文献
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准晶的对称性和物理性质 总被引:9,自引:0,他引:9
本文较系统地论述了准晶的对称性和物理性质,内容涉及准晶的对称性与点群,群的表示理论与准晶的弹性性质,准晶的平衡性质热力学与物理性质张量等诸多方面,其中也包含了本研究小组近年来在这方面的工作和所取得的重要成果 相似文献
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摘要:ICl作为一种强氧化剂并广泛用于生产农产品,自身具有毒性并且严重破坏大气臭氧层,本文通过外加电场研究其物理特性和解离特性。本文采用Hartree-Fook的方法在GDZVP基组水平上增加不同外电场( -0.020- 0.020a. u.) 对ICl分子的基态稳定电子结构进行了计算,研究了外电场对ICl分子的分子结构、键长、偶极矩、总能量、能隙以及红外光谱、势能面的影响规律。结果显示在外电场的作用下分子结构变化显著,随着Z(I-Cl键)方向的外电场的增大,ICl分子键长一直减小,总能量先增大后减小,电偶极矩先减小后增大,能隙EG先增大后减小,同时ICl红外光谱的最强峰先发生蓝移再发生红移,另一方面当电场强度为-0.04a.u.时外电场使I-Cl键断裂,这也证实了研究ICl分子在外电场物理性质是有意义的 相似文献
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质子与重离子肿瘤治疗的进展 总被引:4,自引:2,他引:2
简要介绍了质子与重离子肿瘤治疗的历史和现状.现在,全世界有质子治疗中心23家,治疗肿瘤患者总数为39 612人;重离子治疗设备有3台,治疗肿瘤患者4 511人(包括He离子治疗2 054例病人). 相似文献
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对HIRFL浅层肿瘤治疗终端提供的碳离子束的物理特性进行了首次测量. 结果显示, 能量为80.55MeV/u的12C离子束, 其束流强度在0.001—0.1nA范围时, 直径50mm照射野的均匀性为73.48%, 束流强度在一段时间内的稳定性为80.87%. 测得了束流在治疗装置等中心处的深度剂量分布, 其高剂量的Bragg峰位处在13.866mm的水等效深度, 反推出碳离子束在等中心处对应的能量为71.71MeV/u, 与计算值基本吻合. 对自由空气电离室的读数进行了吸收剂量的标定. 测量结果显示, HIRFL浅层肿瘤治疗装置性能与临床治疗的要求相比稍有差距, 为了达到治疗终端进行临床试验的要求, 须对治癌装置性能做进一步的优化. 相似文献
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硫属玻璃是具有优良红外透过性质的光学材料.为了便于硫属玻璃系统的研究和设计,采用现有的玻璃性质计算理论,运用Delphi语言编程设计实现了硫属玻璃的物理性质计算及配方设计程序. 相似文献
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A pulse pressure was imposed on the melt in the injection molding cavity during the injection and holding pressure stages, called vibration-assisted injection molding (VAIM) technology. With the VAIM technology, biaxially self-reinforced high-density polyethylene (HDPE) samples were prepared and the physical properties affected by the vibration processing conditions were studied. The tensile properties can be improved in both the machine direction (MD) and the transverse direction (TD) by changing the vibration frequency and vibration pressure amplitude, respectively. The elongation at break increased with increasing the vibration frequency for the VAIM sample processed at constant low vibration pressure amplitude; the yield strength increased with increasing the vibration pressure amplitude for the VAIM sample prepared at constant low vibration frequency. The softening point temperature for the VAIM sample increased by 8°C compared with a conventional injection-molded (CIM) sample. 相似文献
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全球气候变化是一个复杂的科学问题,它涉及到气候系统或地球系统的变化,不但需要考虑它们所包含的这些系统内各部分本身的变化,以及它们之间复杂的相互作用,而且还需考虑物理与地球生物化学等许多过程.文章主要讨论全球气候变化中的物理问题,主要有三个方面:(1)辐射传输和全球辐射平衡:不论是由于自然的原因或人类活动(如太阳活动与火山爆发以及温室气体排放增加导致的温室效应加强)一旦破坏全球的辐射平衡,则会引起气候变化,这是气候变化的主要原因与驱动力;(2)大气波动和气候变化的内部变率:除上述外强迫的作用外,气候变化还可由气候系统内部的变率引起,这包括大气内部变率和耦合气候变率.它们主要是通过产生各种大气的波动而实现的.其中最重要的是罗斯贝(Rossby)波.它们的传播和不稳定发展是造成气候变化的另一个原因;(3)气候系统的混沌性质和可预报性:数值预报模式的预报结果对初始场很敏感,即初始场的微小误差可导致完全不同的预报结果,同时模式中物理过程描述的真实程度也影响预报的结果.大气的这种混沌性质限制了天气的可预报性在2周以内.但气候预测由于明显受外强迫的作用,可使大气的混沌时效延长到月、季、年、几十年甚至上百年.为了减少由初始场误差和模式不完善而造成的预报误差,目前气候预报是采用多初值和多模式的集合预报方法,因而气候预测实际上是一种概率预报. 相似文献
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Using the crystal structure prediction method based on particle swarm optimization algorithm, three phases(P nnm, C2/m and Pm-3 m) for InS are predicted. The new phase Pm-3m of InS under high pressure is firstly reported in the work. The structural features and electronic structure under high pressure of InS are fully investigated. We predicted the stable ground-state structure of InS was the P nnm phase and phase transformation of InS from P nnm phase to P m-3 m phase is firstly found at the pressure of about 29.5 GPa. According to the calculated enthalpies of InS with four structures in the pressure range from 20 GPa to 45 GPa, we find the C2/m phase is a metastable phase. The calculated band gap value of about 2.08 eV for InS with P nnm structure at 0 GPa agrees well with the experimental value. Moreover, the electronic structure suggests that the C2/m and P m-3m phase are metallic phases. 相似文献
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A general principle of causal duality for physical systems, lying at the base of representation theorems for both compound and evolving systems, is proved; formally it is encoded in a quantaloidal setting. Other particular examples of quantaloids and quantaloidal morphisms appear naturally within this setting; as in the case of causal duality, they originate from primitive physical reasonings on the lattices of properties of physical systems. Furthermore, an essentially dynamical operational foundation for studying physical systems is outlined; complementary as it is to the existing static operational foundation, it leads to the natural axiomatization of causal duality in operational quantum logic. 相似文献