Cell Locating with the Image Analysis System of the CAS-LIBB Single-Particle Microbeam Facility

A single-particle microbeam facility has been constructed at the Key Laboratory ofIon Beam Bioengineering (LIBB), Chinese Academy of Sciences (CAS). At the CAS-LIBB microbeam facility, we have developed protocols to place exact numbers of charged particles through nuclear centroids of cells, at defined positions in the cytoplasm relative to the nucleus, and through defined fractions of cells in a population. In this paper, we address the methods for nucleus, cytoplasm and bystander (either a single or an exact number of ions is delivered to a certain percentage of cells in a population to study the bystander effects of radiation) irradiation in detail from theprecision of target finding and cell locating in the image analysis system. Moreover, for cells touching slightly in an image, a watershed method is used to separate these touching objects;after that, the number of objects in an image is counted accurately and the irradiation points are located precisely.     

The Experiment of Obtaining Micron Beam in the Single-Particle Microbeam Facility of the Institute of Plasma Physics

The Experiments, methods and results of obtaining micron beam in the Microbeam Facility of the Institute of Plasma Physics were discussed in this paper. The H2^ beam was accelerated by the Van de Graa/f electrostatic accelerator, and the collimator at the end of the beam line is a 60μm thick stainless steel chip. And as a result, particle tracks on the solid track probes (CR39 film) etched in the solution of NaOH showed that the beam can go through the collimator with a small aperure (2000, 300, 55, 30, or 10μm) and 3.5μm thick vacuum film(Mylar). Besides the CR39 method, the beam was measured by an energy spectrum detector after the 10μm diameter aperture and the 3.5 μm thick vacuum film too.     

Consideration about the Single-neutron Microbeam Facility

A conception of the single-neutron microbeam facility was put forward in this paper. The specific particle (e.g. H^ , ^2d^ or α ) bombarding a specific target can generate neutron, when the particle energy is more than a threshold (e.g., H^ energy is more than 2 MeV). And if the specific beam spot on the target is very small, the neutron beam along the direction of the specific beam spot will be very small too. If the neutron beam is weak and a neutron detector is mounted after the specific neutron collimator, the single- neutron will be obtained. Therefore, if the specific target and the neutron detector are installed after the proton accelerator and the microbeam system, the single-neutron microbeam will probably be obtained.     

Analysis and Optimization of Stability of CAS-LIBB Single Ion Microbeam

Single ion microbeam is the most advanced technology which can emit a single ion for precise localization. A single-ion microbeam facility has been constructed at the Key Laboratory of Ion Beam Bioengineering （LIBB）, Chinese Academy of Sciences （CAS）, with a spatial resolutions of about 5 μm. Based on CAS-LIBB microbeam, three key elements affecting the quality of the system are assessed： the size of beam spot, the energy range and the counting accuracy of implanting ions. Various contributions to the ion beam stability, including the ion source, the terminal voltage of electrostatic accelerator and the components in beam pipeline, are discussed. Analysis shows that the improvement of terminal voltage stability is the most important issue for future optimization of CAS-LIBB facility. Some preliminary investigations and project aimed at optimization and development are proposed as well.     

The Progress of a Microbeam Facility in the Institute of Plasma Physics

The progress of a microbeam facility in the institute of Plasma Physics was discussed in this paper.This kind of equipment can supply single-particle beam which may be implanted into cells in micrometer-radius and measured by a new outstanding detector among global microbeam systems.Measurements by some plain targets showed that the highest current after the accelerator tube can be larger than 20μA ,the H2^ current before the second bending magnet is near 0.9μA ,the current after the second bending magnet is near 0.8μA,and the current of the beam line(after a 2-mm diameter aperture)is near 0.25nA which is enough for the single-particle microbeam experiment.It took scientists 3 months to do their microbeam experiment after setting up the qccelerator beam line and get the microbeam from this equipment.Two pre0collimators were installed between the 2-mm diameter aperture and the collimator to survey the beam.Tracks on the CR39 film ectched in the solution of NaOH showed that the beam can go through the collimator including a 10μm diameter aperture and the 3.5μm thick vacuum sealing film(Mylar).A new method,which is called optimization of the beam quality,was put forward in this paper,in order to get smaller diameter of beam-spot in microbeam system.     

重离子微束装置中真空窗的研究

中国科学院近代物理研究所（IMP）正在兰州重离子加速器（HIRFL）系统中研制中能重离子微束终端,以对重离子进行准确定位和精确计数。应用有限元分析软件对不同结构、不同材料的真空窗进行受力分析,模拟真空窗的形变和等效应力,运用强度理论考察候选真空窗的安全性;运用SRIM程序模拟离子的小角散射、横向射程,详细计算入射离子的能量、真空窗材料和厚度及空气层对束斑展宽的影响;最后提出真空窗适宜的结构、材料及厚度范围。     

Single-Ion Microbeam for Applications in Radiobiology： State of the Art

Single-Ion Microbeam (SIM) is uniquely capable of precisely delivering a predefined number of charged particles (precise doses of radiation) to individual cells or sub-cellular targets in situ. Since the early 1990‘s, there has been an ever-increasing interest in developing and applying the SIM technique to problems in radiobiology for studies of cell and tissue damaged by ionizing radiations. Potential applications for SIM in radiobiology continues to grow and have been diversified. There are currently more than 14 SIM facilities worldwide, and they have been in a constant state of evolution. This paper reviews the current state of SIM research worldwide and the related pivotal technological developments in the fields of both biophysics and radiobiology. Representative applications and the perspective of SIM are also introduced and discussed.     

Improvement of the Energy Stability of the Single Ion Microbeam

Energy instability strongly affects the state and the beam size of the single ion microbeam. A facility based on the Generating Voltmeter was developed to improve the energy stability of the CAS-LIBB （Chinese Academy of Sciences, key laboratory of ion beam bioengineering） single ion microbeam. This paper presents the analysis of the energy＇ instability of the single ion microbeam. A simplified theoretical model is set up to calculate the relationship between the energy instability and the beam spot size. By using this technique, the energy instability is adjusted to about 1%. Stable run-time is over 6 hours. The radius of the single ion beam is reduced by 10% compared to the previous olin.     

图像分割在肺部计数器虚拟刻度中的应用

基于边缘检测及阈值分割算法,采用Matlab编程对一物理体模的CT图片进行了自动分割,区分出肺、肌肉、骨骼3种组织,并对分割出的数据进行了三维重建,实现了体素模型的快速建立。将自动分割出的器官的体积与实际器官的比较,相对偏差小于2%。将体素模型用于肺部计数器的虚拟刻度,结果显示,虚拟刻度与实验结果的相对偏差小于10%。     

Dosimetric Analyses of Single Particle Microbeam in Cell Irradiation Experiment

Single particle microbeam （SPM） is uniquely capable of delivering precisely the predefined number of charged particles to determined individual cells or sub-cellular targets in situ. It has been recognized as a powerful technique for unveiling ionization irradiation mechanisms of organism. This article describes some investigations on the irradiation quality of SPM of major world laboratories by means of Monte Carlo method based on dosimetry and microdosimetry. Those parameters are helpful not only to improve SPM irradiating cell experiments but also to study the biological effects of cells irradiated by SPM.     

应用Ecolego软件计算低、中放固体废物处置场核素在地下水中的迁移

以国内某低、中放固体废物处置场为例,应用Ecolego软件,计算处置场关闭后核素在地下水中的迁移以及对公众造成的照射。通过计算表明,该处置场对于处置含有短寿命核素的废物有较好的效果(3H除外),该处置场对公众造成影响较大的核素为3H和14C,以及长寿命核素。因此,在进行废物处置时,要限制长寿命核素以及3H和14C的量。     

某核设施退役中241Am现场防护方法和评估

在某核设施退役的施工过程中,对²⁴¹Am气溶胶的防护采取了佩戴呼吸器的方式,因此,呼吸器的防护效果至关重要。本文根据工程实践中获得的数据对呼吸器的防护效果进行了计算和评估。结果表明,防护效果能达到目标管理要求,佩戴呼吸器进行现场防护的方法安全有效,可在其他核设施退役工程中推广应用。     

核设施实物保护技术探究

实物保护系统(PPS)是核工程技术领域中一个综合多学科的系统工程,包括探测、延迟、响应三大要素。系统介绍了实物保护系统(PPS)设计与分析的过程和方法以及实物保护系统网络集成,旨在通过采用先进的技术方法来提高实物保护系统的功能性、稳定性与可靠性,使其在保护核材料和核设施安全方面发挥更有效的作用。     

借助CFD方法的燃料转运通道热工水力实验的台架设计

核电厂安全设计中,需要考虑燃料转运过程中的热工安全问题。具体而言,需要研究复杂几何结构内发生于狭窄水平流道的有加热源的自然循环流动传热过程。借助计算流体力学(CFD)方法,对流动传热过程进行了预研,并据此选定了重点研究区域和关键物理现象。结合实验需求,设计了专用的热工水力实验台架,并根据相似理论分析了实验段与原型之间的差异,以及由此引入的误差,为开展进一步的实验研究奠定了基础。     

利用MCNPX模拟钴-60辐照装置研发样品吸收剂量的研究

本文采用高能粒子输运程序MCNPX2.5.0对钴-60辐照装置建立几何模型,对位于辐照室中垂直于双板源架中心点3 m处的研发样品的吸收剂量（率）进行模拟计算。根据实际生产,选择辐照室有或无辐照产品两种工况,一是分别模拟12种不同包装规格且不同质量研发样品在不同辐照时间的吸收剂量;二是模拟计算包装规格相同且质量不同的10种样品的吸收剂量率;三是模拟计算包装规格不同但质量相同的9种样品的吸收剂量率。结果表明,在辐照室有或无辐照产品两种工况下,后者的值比前者平均大4.19倍;三类研发样品的吸收剂量（率）及变化规律可以作为实际生产研发的参考。MCNPX理论模拟计算对于辐照新产品具有重要的实际指导意义。     

核反应堆试验台架比例分析方法的发展和应用

比例分析方法为建立合理的反应堆安全系统缩比试验台架提供了理论基础。本文结合比例分析方法的发展,探讨了不同比例方法的特点,并总结了部分已有台架的比例设计概念及评价,为反应堆系统试验台架比例方法的选取提供了参考。结果表明,线性比例方法中的加速度比例项使其应用受到限制;功率-体积法是一种简单有效的比例方法,但瘦高台架的特点也使此方法存在不可避免的弱点;H2TS（HierarchicalTwo-TieredScaling）方法以PIRT（PhenomenaIdentificationRankingTable）表为基础,对系统中重要整体过程和局部过程均进行了比例分析,其发展的相似准则中含有流体物性比例项,为台架比例概念的发展提供了条件。我国将以H2TS方法为指导建立非能动堆芯冷却系统试验台架ACME。     

使用MCNP程序调整和优化启明星实验装置设计方案

用蒙特卡罗程序(MCNP)对验证ADS系统的启明星实验装置的设计方案进行了有效增殖因数(Keff)计算,并对与Keff密切相关的热区燃料元件栅距和热区厚度进行了最优参数的计算。结果表明,启明星实验装置的Keff能够达到设计的目标。     

聚乙烯材料自动图像处理检测软件系统研制

聚乙烯材料自动图像处理检测软件系统由电机控制．图像采集、图像拼接和图像处理与分析部分组成本文介绍了该系统的设计制作,并将其应用于试件内部缺陷的检验分析中,结果表明,该系统原理正确,结构可行,性能可靠。     

MCNP模拟钴-60辐照装置空间剂量场

为模拟辐照室中辐照工位外的周围空间剂量场分布,采用蒙特卡罗粒子输运程序MCNP建立钴-60辐照装置模型。以单板源架中心点为坐标原点的笛卡尔坐标系,考虑钴-60源的γ射线非自吸收和自吸收两种情况,研究坐标轴方向上每隔10 cm间距的空气平面的剂量率和坐标轴上剂量率的变化规律。结果表明,辐照室中辐照产品占满辐照工位的情况下,周围空间剂量场空气面剂量率整体较小;单板源架中心坐标轴上的剂量率变化规律更符合二项式拟合函数。在钴-60源γ射线自吸收情况下,单板源架端面坐标轴附近的空气面剂量率明显偏小,且随着空气面远离单板源架,空气面上的高剂量率区域向两侧移动;在钴-60源γ射线非自吸收情况下,单板源架端面处的空气面高剂量区域始终位于坐标轴附近。MCNP理论模拟计算分析对于利用钴-60辐照装置辐照工位外的周围空间剂量场具有重要的实际指导意义。     

核设施退役土壤中氚允许残留量限值推定的一种方法

本文应用美国能源部的程序ＲＥＳＲＡＤ５．０对我国某氚实验设施场址给出了土壤中残留氚容许限值与年有效剂量目标的关系。介绍了所用方法,主要计算公式和最后结果。