跑道式医用电子回旋加速器的原理

带电粒子加速器是核物理实验研究的重要工具，在恶性肿瘤的放射治疗中占有重要的地位。着重介绍了电子回旋加速器原理，重点介绍了跑道式电子回旋加速器的工作原理，并对电子回旋加速器和电子直线加速器的特点进行了比较。     

医用电子直线加速器工作原理与故障排除

医用电子直线加速器是一种应用于肿瘤治疗的大型放疗设备，其作用机理是利用高能X射线照射病灶部位以消灭病变细胞。本文以WDVE6／100型驻波电子直线加速器为例，对医用电子直线加速器的工作原理进行简单描述，然后用实例详述了故障检修方法，并对部分电路原理进行分析。     

医用电子直线加速器的技术应用与研究

目的：分析研究医用电子直线加速器的设计原理，定性、定量地解析研究加速器的技术关键，深入探索加速器的核心细节。方法：应用总分类的逻辑思路，从国内肿瘤情势的分布、行业的需求及放射治疗设备本身的技术发展，研究分析医用加速器的工作原理、技术应用、设计细节。结果：医用电子加速器电子的获得、微波加速及内部环境支撑，其核心是微波类型的应用，而且加速管的结构至关重要。结论：驻波电子直线加速器较行波电子直线加速器的发展晚，是由于稳定的加速电子结构和技术不成熟所致。巧妙的新型边耦合加速结构，为加速器的研究提供了技术支持与保障。     

HM-J-16-I型医用电子直线加速器自动频率控制系统

自动频率控制系统（简称AFC系统）是医用电子直线加速器中微波功率源输出的微波频率的控制系统，其性能的优劣直接影响到微波频率的准确性和稳定性，从而影响加速器输出射线的物理指标，是一直受关注的关键部件之一。本文阐述了江苏海明医疗器械有限公司HM-J-16-I型医用电子直线加速器AFC系统的工作原理和设计方法。     

BJ—6B医用加速器剂量控制原理及故障分析

ＢＪ—６Ｂ医用加速器剂量控制原理及故障分析解放军第三○四医院张永敏ＢＪ—６Ｂ医用加速器是北京医疗器械研究所生产的新一代机种。它采用全微机控制，自动化程度较高，是目前国内比较先进的放疗设备。它在剂量控制方面采用了三级保护措施，即两道剂量通道保护，一道时...     

瓦里安23EX加速器内循环水系统及其常见故障的分析

为保证医用直线加速器工作性能稳定的水循环恒温系统是加速器的重要组成部分,尽管不同加速器的内循环水系统不完全一样,但其原理相通、结构大同小异。对于加速器的维护人员来说,熟知内循环水系统的原理和结构,准确、快速判断并修复系统经常出现的故障,对提高加速器的开机率、延长其使用寿命具有一定的重要意义。     

PRECISE医用加速器温度传感器故障的鉴别和维修

PRECISE医用直线加速器中的温度传感器安装在机头内电离室附近，共2个，分别用于监测输出束流剂量通道1和剂量通道2的实时温度。其功能是根据感应出现场的温度变化对医用加速器的绝对输出放射剂量进行修正补偿。该元件与加速器的输出剂量直接相关，故主系统将其纳入故障联锁。基本工作原理和过程是：通过加速器12区的AI12A和SCCA电路板读取25区机头电离室附近的温度传感器1的数据：     

浅析医用加速器辐射剂量测量仪的现状及发展

医用加速器是放射治疗肿瘤的主要仪器,其输出剂量的准确性对临床治疗肿瘤具有重要意义。本文分析比较几种国内常用的医用加速器的辐射剂量测量仪,论述了不同辐射剂量测量仪的工作原理、功能特性及优缺点,不同辐射剂量测量仪的综合应用与研究进展,为放疗基础和临床治疗的安全准确性提供了理论依据。     

医科达COMPACT加速器AFC系统的工作原理与维修

医科达公司COMPACT直线加速器是6MV单光子的入门级加速器，性价比高，应用前景广泛。AFC（微波频率自动控制）系统是使加速器正常工作的重要组成部分。本文主要介绍COMPACT加速器AFC系统的工作原理与故障检修。     

WDVE-6/100型医用加速器微波系统原理及故障维修一例

医用电子直线加速器是应用于肿瘤治疗的大型医疗设备,其主要作用原理是利用高能X线杀灭病变细胞。本文对WDVE-6/100型电子直线加速器的微波系统原理进行了阐述,并结合实例详述具体检修方法。     

Calcium intake in the elderly: validation of a dietary questionnaire

Epidemiological studies of calcium and osteoporosis have been hampered by the lack of a suitable tool for assessing calcium intake. This report describes a new frequency and amount questionnaire for measuring present and past calcium intake in the elderly. The validity of the questionnaire was tested against two commonly used standards of dietary assessment, five-day duplicate diets and seven-day weighed dietary inventories. The resulting correlation coefficients were, respectively, r = 0.76 and r = 0.69, while that for repeatability was r = 0.84. Furthermore, the questionnaire categorized subjects into thirds of the distribution of intake with almost no gross misclassification. It is suggested that the present findings may be extended to the majority of normal, healthy elderly subjects, implying wide application for the questionnaire in the assessment of calcium intake in the elderly.     

The occurrence of antimicrobial substances in toilet,sink and shower drainpipes of clinical units: A neglected source of antibiotic residues

Antibiotics represent one of the most important drug groups used in the management of bacterial infections in humans and animals. Due to the increasing problem of antibiotic resistance, assurance of the antibacterial effectiveness of these substances has moved into the focus of public health. The reduction in antibiotic residues in wastewater and the environment may play a decisive role in the development of increasing rates of antibiotic resistance. The present study examines the wastewater of 31 patient rooms of various German clinics for possible residues of antibiotics, as well as the wastewater of five private households as a reference.To the best of our knowledge, this study shows for the first time that in hospitals with high antibiotic consumption rates, residues of these drugs can be regularly detected in toilets, sink siphons and shower drains at concentrations ranging from 0.02?μg·L^?1 to a maximum of 79?mg·L^?1. After complete flushing of the wastewater siphons, antibiotics are no longer detectable, but after temporal stagnation, the concentration of the active substances in the water phases of respective siphons increases again, suggesting that antibiotics persist through the washing process in biofilms. This study demonstrates that clinical wastewater systems offer further possibilities for the optimization of antibiotic resistance surveillance.     

Self-reported health problems among Swedish miners one year after unemployment

Unemployment is considered to be a public health concern sincedeterioration in the health of the unemployed is often anticipated.However, for some groups, such as miners, unemployment mightimprove health due to a cessation of potentially harmful occupationalexposures. This study evaluates the health of 79 miners in oneSwedish iron-ore mine, and 226 age-matched controls from thegeneral population, during one year after the closure of themine. The participants received a questionnaire regarding medicalhistory and subjective symptoms at the beginning of the studyperiod, and after one year. Statistically significant negativeeffects on self-reported health attributable to unemploymentwere not found, although neuropsychiatric symptoms were morecommon among the unemployed miners. The miners reported a statisticallysignificant improvement in grip force (p=0.031). They had asignificantly higher prevalence of symptoms associated withmining related exposures when compared with the population controls;pain in the upper extremities [relative risk (RR)=2.27, 95%confidence interval (Cl)=1.44–3.59), back pain (RR=1.84;Cl=1.237–2.75), vasospastic disease of the fingers (RR=2.05;Cl=1.18–3.57) and obstructive respiratory symptoms (attacksof dyspnea and wheezing: RR=3.67; Cl=1.167–11.6).     

Excès de cas humains et animaux de tularémie en France au cours de l’hiver 2007–2008 : émergence ou phénomène isolé ?

Context

Tularemia is a zoonosis affecting humans and hares in France. We describe the results of surveillance in both species, in 2007 and 2008.

Methods

Human tularemia cases are mandatorily notifiable in France since 2003. In hares, surveillance relies on volunteer hunter associations in all districts of the country. Data from mandatory reports and volunteer surveillance in 2007/2008 were analyzed and compared with previous results.

Results

In 2007/2008, 144 cases were reported in humans and 117 cases in hares. This was a 100% increase compared to previous years. Human cases differed from those of previous years only by the frequency of contact with breeding animals. Human cases without any documented risk exposure were also more frequent.

Conclusion

An increase of tularemia cases occurred in 2007/2008 in both species. Complementary studies are needed to identify the species reservoir in France to understand the causes of this peak of cases.     

Occupational health hazards in mining: an overview

This review article outlines the physical, chemical, biological, ergonomic and psychosocial occupational health hazards of mining and associated metallurgical processes. Mining remains an important industrial sector in many parts of the world and although substantial progress has been made in the control of occupational health hazards, there remains room for further risk reduction. This applies particularly to traumatic injury hazards, ergonomic hazards and noise. Vigilance is also required to ensure exposures to coal dust and crystalline silica remain effectively controlled.     

Manufacture and use of nanomaterials: current status in the UK and global trends

This paper provides an overview of the production and use of nanomaterials (NMs), particularly in the UK. Currently, relatively few companies in the UK are identifiable as NM manufacturers, the main emphasis being the bulk markets in metals and metal oxides, and some niche markets such as carbon nanotubes and quantum dots. NM manufacturing in the UK does not reflect the global emphasis on fullerenes, nanotubes and fibres. Some assumptions have been made about the types of NM that are likely to be imported into the UK, which currently include fullerenes, modified fullerenes and other carbon-based NMs including nanotubes. Many university departments, spin-offs and private companies have developed processes for the manufacture of NMs but may only be producing small quantities for research and development (R&D) purposes. However, some have the potential to scale up to produce large quantities. The nanotechnology industry in the UK has strong R&D backup from universities and related institutions. This review has covered R&D trends at such institutions, and appropriate information has been added to a searchable database. While several companies are including NMs in their products, only a few (e.g. manufacturers of paints, coatings, cosmetics, catalysts, polymer composites) are using nanoparticles (NPs) in any significant quantities. However, this situation is likely to change rapidly. There is a need to collect more information about exposure to NPs in both manufacturing and user scenarios. As the market grows, and as manufacturers switch from the micro- to the nanoscale, the potential for exposure will increase. More research is required to quantify any risks to workers and consumers.     

深圳公立医院管理体制改革制度设计

深圳公立医院管理体制改革实行政事分开、管办分开,在理事会架构下按法定机构模式组建市医管中心,落实公立医院运营管理自主权.作者从当前公立医院管理体制的弊端入手,介绍了深圳市进行公立医院管理体制改革的基本思路及改革方案设计的主要举措,深入剖析了的改革方案的特点,并对改革效果进行了预测.     

Effects of nitrogen dioxide on red blood cells of rats: Changes in components of red cell membranes during in vivo exposure to NO2

Red cell membranes, prepared from red blood cells of rats exposed to 4, 10, or 20 ppm nitrogen dioxide (NO₂) for 1 to 10 days, were examined for evidence of changes in membrane components. Appreciable changes were not found in contents of phospholipid and cholesterol during exposure to 10 ppm NO₂. By contrast, protein content altered with the time of exposure. Moreover, changes in protein composition were observed by employing sodium dodecyl sulfate — polyacrylamide gel electrophoresis. Twenty-four-hour exposure to NO₂ at the concentration above 10 ppm resulted in a marked increase in the percentage of lysophosphatidylethanolamine (LysoPE) to the total phospholipids. The prolonged exposure to 10 ppm NO₂ gave rise to a further increase in LysoPE, whereas the percentage of phosphatidylethanolamine (PE) showed a gradual decrease. A 1-day exposure to 4.0 ppm NO₂ also caused an increase in sialic acid content and decreases in those of PE and hexose. In addition to contents of these components the percentage of LysoPE increased 5 days after exposure and the elevated values were maintained up to the end of exposure period. These results demonstrate that red blood cells in circulation exhibit different membrane properties in terms of lipid and carbohydrate composition during 10 days of exposure to 4.0 ppm NO₂.     

Investigating clusters in the workplace and beyond

Clusters of disease are common and occur in the workplace and in the general community. They often arouse considerable concern among the population. Investigations have sometimes lead to exciting new knowledge, but in general the investigation of clusters is difficult and often unrewarding, especially for community clusters. In the workplace, investigations are more likely to find associations and even new causes, but still many clusters remain enigmatic. Despite this, there are many reasons for investigating clusters, including allaying community concern and identifying uncontrolled exposures. A structure for investigating clusters in the workplace is suggested.