Omega 500γ相机的性能测试和质量控制

γ相机及SPECT的质量控制国际上已有许多学术团体和组织进行了系统研究,我国近年来也把这项工作从单纯常规测试转入研究课题,并有一些报道。关于质量控制和性能测试的关系应有明确的概念。从机器验收和检验机器性能变化出发,性能测试是主要的,但从临床质量保证考虑,以得到最佳诊断结果为目的,除了性能测试以外,还应有其他一些与临床有关的条件保证。本文将从临床机器质量保证出发,介绍Omega 500的质量控制,有些性能指标的测试则相应从简。     

基于Adaboost算法的核电站故障诊断方法

针对当前基于集成学习的核电站故障诊断算法大多注重提高各种机器学习算法识别精度而忽略底层基学习器整合方法,导致集成学习算法识别事故类型精度难以提高,而且存在识别结果是否可信的问题。本文基于Adaboost算法设计了一种可使核电站控制系统自主识别故障类型的机器学习算法模型,该算法模型通过为集成学习的各种故障识别算法合理分配权重系数,提升集成学习整体算法对核电站事故类型的识别精度和算法可靠性。同时测试结果表明Adaboost算法对7种典型的核电站运行或事故工况的平均识别正确率可达95%以上;而且当事故发生150 s后,识别正确率可达100%。因此基于Adaboost算法的基学习器整合方法可用于优化集成学习的算法结构,提高算法对核电站事故类型的识别精度。      

核电厂两种实时故障诊断系统的对比

分别利用模糊神经网络技术和数据融合技术,采用VB6.0编程语言开发了核电厂实时故障诊断系统,并对诊断系统中所应用的智能诊断算法进行了详细的阐述.为比较直观地对比两个诊断系统,利用数据通讯程序接口使该诊断系统与仿真机进行实时数据交互,并在仿真机上设置了4种故障对两个诊断系统进行在线测试.测试结果表明,应用模糊神经网络技术和数据融合技术均能对故障进行识别,但都存在各自的优点和不足.离线分析表明,针对不同的故障类型,当特征参量较少时,采用模糊神经网络诊断技术较好;而特征参量较多时,最好采用数据融合诊断技术.     

Biograph 16HR PET/CT性能测试与长期追踪

遵照NEMA NU2-2001标准对Siemens产的Biograph 16HR型PET/CT的性能进行了测试,给出了空间分辨率、散射分数、计数丢失及随机符合、系统灵敏度及图像质量。近三年来对机器进行跟踪,还给出了稳定性表现和总体性能。CT部分参考北京疾病控制中心"CT验收程序",给出了该机器CT部分的CT值、CT均匀性、CT空间分辨率。对于PET与CT结合后的性能指标,测试给出了两者融合精度这一指标。机器三年来性能稳定,各项指标均达到要求。     

上海光源储存环机器保护系统升级

上海光源线站工程（二期）对机器保护系统提出的高要求是现有系统无法满足的,需对机器保护系统进行升级改造。本文使用FL-net技术实现了光源储存环所有联锁可编程逻辑控制器单元间的数据共享,解决了联锁系统跨单元通信的问题。机器保护系统的远程控制基于分布式EPICS设计,扩充部分通过统一接口形式和使用层次化设计方法,避免了对原系统的改动。新系统通过测试,在线运行可靠稳定,单元间联锁响应时间小于21 ms,满足加速器运行的需求,且改造后的系统更灵活、易扩充,可满足日后不同的联锁需求。     

上海光源储存环机器保护系统升级

上海光源线站工程(二期)对机器保护系统提出的高要求是现有系统无法满足的,需对机器保护系统进行升级改造。本文使用FL-net技术实现了光源储存环所有联锁可编程逻辑控制器单元间的数据共享,解决了联锁系统跨单元通信的问题。机器保护系统的远程控制基于分布式EPICS设计,扩充部分通过统一接口形式和使用层次化设计方法,避免了对原系统的改动。新系统通过测试,在线运行可靠稳定,单元间联锁响应时间小于21 ms,满足加速器运行的需求,且改造后的系统更灵活、易扩充,可满足日后不同的联锁需求。     

FL-PFS法快速识别γ谱中低计数率核素

探讨了一种基于模糊逻辑与概率因子迭加算法识别γ谱中低计数率核素的分析方法。对²⁴¹Am、¹³³Ba、¹³⁷Cs、⁶⁰Co、¹⁵²Eu五种核素不同测试时长的多核素实测谱进行测试。结果表明,本算法随着迭加次数的增加,核素识别率迅速上升。概率因子迭加次数达到15次以上时,核素识别准确率增长趋势变缓,对不同测试样本的识别率均在98%以上。该算法比传统算法具有更高的识别率,尤其在对多核素混合的复杂核素谱识别方面表现出较强的优势。     

新型数字BPM信号处理器研制进展

介绍了采用Arm微处理器技术、FPGA数字信号处理技术、高速带通欠采样技术的新型BPM信号处理器研制进展情况;对两类主要的原理样机进行了评估测试.信号处理算法评估样机基于商业评估板搭建,用于测试包含数字下变频、低通滤波、抽取降速等信号处理算法功能模块.自主开发的硬件评估样机用于测试不同硬件功能模块及整机集成后的硬件性能...     

医用诊断X线机防护改装效果浅析

本文介绍了对医用诊断 X 线机进行防护改装的方法及其防护性能的测试结果。从渡口市不同容量和类型的20台医用诊断 X 线机改装前后的测试结果可以看出,防护改装的方法是可行的,改装的效果比较好。     

基于CUDA的大型γ辐照装置通用并行排源算法

本文利用CUDA执行模型实现了植物模拟生长算法的完全并行化,结合标准排源质量评价数学模型,得到了一种高效率的并行排源算法,对应的代码能运行在GPU上。在此基础上,利用若干不同规模的排源算例对新版本算法进行了测试。测试结果表明,在保持已有版本算法优点的基础上,新算法的计算效率相对CPU版本提升了500倍以上,相对CPU+GPU混合版本,也提升了30倍以上。对111 PBq以下装置,新算法的计算时间小于10 min。利用单GTX275 GPU,新算法的计算性能上限为167 PBq左右,时间不超过25 min,利用多GPU还可提高计算能力。综上所述,基于GPU的新版本算法可满足目前国内任意规模γ辐照装置的高质量排源需要,具有高度的竞争力。     

Identification of radiation treatment of wheat （Triticum aestivum. L）and rice （Oryza sativa. L） samples using thermoluminescence of contaminating minerals

Food irradiation is gaining popularity worldwide and this technology is important to improve quality and reduce the post harvest losses of food. Because of the rapid commercialization of irradiated foods throughout the world, compliance of different regulations relating to use of technology in different countries and demand of consumers for clear labelling of irradiated foods, there is need for the development of analytical methods to detect radiation treatment of food. Among several methods studied so far, thermoluminescence （TL） is an important method that can be used to find out the irradiation history of food that contain even a very minute amount of dust particles. In this study, the irradiated and unirradiated wheat and rice samples were analyzed using the TL method. The samples were purchased from the local market of Peshawar and irradiated to radiation doses of 0.5 and 1.0 kGy using Co-60 gamma irradiator at the Nuclear Institute for Food and Agriculture （NIFA）, Peshawar. The mineral contaminants were isolated by jet water, ultrasonic treatment, and density gradient. TL glow curves of the isolated minerals from irradiated and unirradiated samples were recorded between the temperature ranges of 50-500℃ using a TL reader. Generally, the glow curves for irradiated samples showed much higher TL intensities （TL1） than the unirradiated samples. The results were normalized by rerradiation of mineral samples to gamma-ray dose of 1.0 kGy followed by determination of the second glow curves （TL2）. The ratio of the area of first glow curve to that of second glow curve （TL1/TL2） was calculated for selected temperature intervals and compared with the recommended values for unirradiated and irradiated samples. Finally, the shapes of the glow curves for irradiated and unirradiated samples were also analyzed. On the basis of these results （comparison of TL-intensities, TL1/TL2 ratios and shapes of the glow curves）, all the irradiated and unirradiated samples of wheat and rice were unequivocally identified.     

有效探测面积大于1000 cm2的正比计数器测量系统性能测试

为对自制的活性面积高达1 000 cm²的大面积源进行表面发射率定值,同时作为现有2πα、2πβ表面发射率标准装置能力的扩充,研制了一套内置式大面积2π多丝正比计数器测量系统,并利用活性区直径为8 mm的²⁴¹Am点源及活性区面积为10 cm×15 cm的大面积²⁴¹Am和⁹⁰Sr-⁹⁰Y源对其进行计量学性能测试。结果表明：计数器内计数响应均匀性优于±0.4%,有效探测面积达1 400 cm²;所得²⁴¹Am源高压坪曲线的坪长为1 400 V,坪斜为0.27%/100 V,坪区内计数变化为0.87%;⁹⁰Sr-⁹⁰Y源高压坪曲线的坪长为300 V,坪斜为0.75%/100 V,坪区内计数变化为0.80%;10次测量重复性好于0.4%,8 h内短期稳定性好于0.3%,1 a内长期稳定性好于0.8%。     

Preparation of Zn/TiO2 powder and its photocatalytic performance for oxidation of P-nitrophenol

Zn-doped TiO2 catalysts were prepared using a sol-gel method and characterized by XPS,UV-Vis, BET, XRD in this study. Under the irradiation of simulant sunlight, the photocatalytic activity for the degradation of p-nitrophenol was studied too. After irradiation for 2.5 h, the degradation percentage of p-nitrophenol could rise to more than 80 %. The results showed that the spectrum absorption band edge of Zn/TiO2 powder does not broaden obviously comparing with pure TiO2 powder. Zinc exists as Zn （11）. When calcined at 973 K, there is a new phase as ZnTiO3 in Zn/TiO2 catalyst. The order of photocatalytic activity of Zn/TiO2 catalysts calcined at different temperatures for p-nitrophenol is 773 K 〉 673 K 〉 873 K 〉 573 K 〉 973 K and the photocatalytic activity of Zn/TiO2 catalyst calcined at 773 K is better than TiO2 catalysts heated at the same temperature, and outclasses that of commercial TiO2 catalyst. It also showed that the photocatalytic degradation of p-nitrophenol follows first-order kinetics under the irradiation of simulant sunlight.     

Current status of radiation therapy for prostate cancer

Radiotherapy for the treatment of prostate cancer has been extensively explored in the past. Along with the comprehensive understanding of the biology of prostate cancer and rapid advances in terms of technology, the out- come of treatment for the patients with prostate cancer has improved. The authors review radiotherapy as the primary treatment for the disease, with particular emphasis on the technological advances from both the radiobiological and radiophysics aspects. Nonconventional fractionated irradiation like hyper- or hypo-fractionation has been imple- mented in the clinic, the final results still need to be confirmed in the future. Technological advances like IMRT, IGRT, in the last two decades have significantly improved the delivery of external radiotherapy to the prostate. This has re- sulted in an overall increase in the total dose that can be safely delivered to the prostate, which has led to modest im- provements in the biochemical outcome. However, establishing the standard therapy for prostate cancer remains con- troversial. It is hoped that the next decades will bring continued advances in the development of biologicals that will further improve current clinical outcomes.     

The control system for SSRF injection and extraction

This paper introduces the injection and extraction control system design for SSRF,which is a distributed control system aimed at stability and reliability of the pulse power supplies,PPS(Personnel Protection System)and MPS(Machine Protection System).The hardware environment is mainly based on PLC(Programmable Logic Con- troller),and ARM(Advanced RISC Machine)is also applied for studying stability of the power supplies.WinCC and EPICS(Experimental Physics and Industrial Control System)have been selected as the platforms of SCADA(Super- visory Control and Data Acquisition).For unifying the interfacing to the control computer,all front-end equipments are connected via Industrial Ethemet.     

Interaction between uranium and humic acid (Ⅰ): Adsorption behaviors of U(Ⅵ) in soil humic acids

The adsorption behaviors of uranium on three soil humic acids (HAs), which were extracted from soils of different depths at the same site, were investigated under various experimental conditions. The adsorption results showed that U(Ⅵ) in solutions can be adsorbed by the three soil HAs, with the order of FHA (HA from 5 m depth of soil) ＞SHA (HA from the surface) ＞THA (HA from 10 m depth of soil) for adsorption efficiency in each desirable condition, and the adsorption reached equilibrium in about 240 min. Although the maximum adsorption efficiency was adsorption could be described with Langmiur isotherm or Freundlich isotherm equation. The L/S (liquid/solid, mL/g)ratio and pH were important factors influencing the adsorption in our adsorption system besides uranium concentration. The adsorption efficiency decreased with the increase of the L/S ratio and pH at the pH range of 2.0-3.0 for SHA and THA or 2.5 - 6.0 for FHA. However, no significant difference in adsorption of U(Ⅵ) was observed at the experimental temperature. All the results implied that humic substances have different characteristics in samples even collected at the same site.     

水平管内含空气蒸汽强制对流冷凝换热模型研究

为研究含空气蒸汽在水平管内强制对流冷凝换热特性,基于对传热传质过程的分析,建立了管内为环状流与波状流条件下的流动冷凝换热模型。从潜热、显热和液膜3个环节对整个换热过程进行建模,最终得到计算局部冷凝换热系数的理论关系式。模型预测结果与实验数据的对比表明,二者相对偏差在±20%以内,验证了该换热模型的准确性与适用性。通过进一步的研究发现：从换热管入口至出口,随着冷凝的进行,管内换热主要热阻由液膜热阻向气液界面的凝结热阻转变;主流气体对流换热过程基本可忽略。     

Information for authors

<正>1.NUCLEAR SCIENCE AND TECHNIQUES(NST),a bimonthly journal,is devoted to all aspects of nuclear science and technology,theoretical or experimental.Its special interest lies in the subjects of synchrotron radiation science and technology;low energy accelerators,radiation technology and applications;radiochemistry,radiopharmaceuticals and nuclear medicine;nuclear electronics and instrumen-     

PLASMA SCIENCE AND TECHNOLOGY AUTHOR INDEX TO VOLUME 16(2014)

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Web Services interface of SSRF archive data analysis system

Accelerator database stores various static parameters and real-time data of accelerator. SSRF (Shanghai Synchrotron Radiation Facility) adopts relational database to save the data. We developed a data retrieval system based on XML Web Services for accessing the archive data. It includes a bottom layer interface and an interface applicable for accelerator physics. Client samples exemplifying how to consume the interface are given. The users can browse, retrieve and plot data by the client samples. Also, we give a method to test its stability. The test result and performance are described.