国产直线加速器的维修维护和保养

目的:分析和总结国产直线加速器故障发生的原因、维修、维护及保养。方法:根据直线加速器故障维修记录,统计和分析直线加速器磨合期和平稳期故障率和故障特点。结果:直线加速器磨合期性能不稳定故障率高,平稳期性能稳定故障率较低,正确使用和维护保养设备,确保机器在良好的状态运行。结论:科学管理、正确使用、合理维护及保养,设备的运行状态稳定可靠。     

瓦里安Trilogy直线加速器GFIL联锁维修案例

<正>目前，放射治疗作为临床治疗肿瘤手段在肿瘤综合治疗中的使用率越来越高，而医用直线加速器是放疗领域的重要设备之一。随着患者数量的激增，医院直线加速器每天可能持续开机数十小时。因此为确保直线加速器在临床应用中正常运行，对其进行维护就显得格外重要。我院使用的瓦里安Trilogy直线加速器由于工作年限较长，GFIL联锁故障频发。     

瓦里安直线加速器常见故障分析和处理

瓦里安直线加速器是目前国内医用直线加速器使用最广泛的品牌之一,分为各种高中端型号,但基本结构相似.随着放射治疗技术的发展,许多医疗机构的加速器已使用近十年,多数设备的故障率越来越高.医用直线加速器常见故障分为机械故障 [1-2]、电路故障 [3-4]、剂量通路故障 [5-6]、冷却循环系统故障 [6]等.另外,多叶光栅...     

VARIAN 2300EX直线加速器检修四例

直线加速器作为一种远距离放疗设备在各大医院已普遍使用,但因其结构复杂,故障率高,经常会影响到临床治疗工作。现将我院VARIAN2300EX型直线加速器的四例故障及排除方法总结如下,以供大家参考。     

BJ-6M直线加速器常见故障的修理及调整

我院从北京医疗器械研究所引进的BJ-6M型直线加速器，自97年使用至今，工作基本正常。该机器在国产的机器中故障率比较低，工作参数也比较稳定，在国内医院中已有相当多的用户。由于机器中有众多的高压、大功率的器件和众多的联锁器件，使用中出现一些故障在所难免。鉴于该加速器故障有一定的共同性，笔者总结近年对该机器的维护经验，特把该机器的一些常见故障分析如下，与国内的同道们交流。     

VARIAN 2300 C／D型直线加速器枪控制部分原理剖析

CLINAC 2300C／D型直线加速器是美国VARIAN公司生产的C-Series系列加速器中比较高档的一款高能加速器，性能稳定，可靠性强，在国内受到不少用户的青睐。其电子枪驱动部分是故障率相对比较高的地方，出现GFIL联锁有很多原因，要很好地解决此问题，必须首先对原理有一清楚的了解，本文重点介绍了其基本工作原理并分析了典型故障的排除。     

医科达Precise型直线加速器剂量率的调整及故障维修4例

医科达直线加速器是目前国内使用较广的进口加速器之一。Precise型双光子加速器作为这一机型的代表，具有使用方便、故障率低、维修成本低等特点。现介绍一些常规故障的维修方法，供参考。     

Varian 23EX直线加速器真空电源故障处理

真空系统是直线加速器的重要组成部分,故障率较高。通过介绍Varian23EX直线加速器真空系统的基本构成和工作原理、对真空系统常见的联锁信号进行简要分析,以及就一例特殊的直线加速器真空电源故障现象、原因排查过程及故障解决的描述,总结了临床工程师在直线加速器的日常维护中应具备的技能和素质。     

西门子Primus E加速器故障检修二例

Siemens Primus E医用加速器是全数字化直线加速器．自动化程度高，维护方便。大功率微波传输器件、复杂的控制保护电路，故障率相对较高。剂量率故障和无射流输出（即不出束）故障时有发生．整机联锁系统为用户提供了方便的故障诊断代码。通过对相关联锁号码的分析和波形判断，即可快捷、准确地发现问题并及时排除故障。     

西门子Primus H直线加速器脉冲调制系统原理与故障分析

西门子Primus H直线加速器是能对肿瘤进行适形调强放疗的高能电子直线加速器,脉冲调制系统是直线加速器的重要组成部分.在加速器的日常使用过程中,该系统的故障率较高,如果能详细了解系统的原理、构造,将有助于及时地排除设备故障. 1 脉冲调制系统原理与分析 在电子直线加速器中,为了得到尽可能高的加速电场,进而产生大功率的微波源,就需要脉冲调制系统来完成这一工作,脉冲调制系统基本原理框图如图1所示.由触发器电路触发脉冲调制器,产生一定功率的、一定重复频率的和一定宽度、波形合适的高压脉冲电压,经过微波传输系统进入加速管[1].因此加速器的性能和工作的可靠性与脉冲调整器产生的脉冲质量有直接关系.     

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.     

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.     

Assessing occupational and environmental exposure

Exposure assessment is a poorly understood component of the science of epidemiology. The relationship between exposure to chemicals and ill-health outcomes is often calculated using crude exposure measures such as ever/never exposed or duration. When investigating subtle effects, exposures need to be characterized much more fully in terms of intensity, frequency, duration and route. While occupational exposures tend to be much greater than those experienced from the wider environment there is a need to remember that, for many chemicals, exposure can occur occupationally, environmentally and through consumer use of products containing the material of interest. Inhalation exposure has generally been the traditional focus for most epidemiological investigations but there is now growing awareness of the importance of the dermal and ingested routes of contact and internalization. Quantification of the exposure also needs to be related to a biological mechanism of action and exposure metrics need to be selected accordingly. Occupational exposures can generally be measured using simple well-validated techniques. Environmental exposures require much more sensitive instruments and are more difficult to assess. Exposure modelling, particularly for the environmental fate of chemicals has undergone many recent developments and Monte Carlo techniques can be used to characterize model uncertainty and variability. This approach to exposure assessment can now be used in the setting of the wider environment and will enable a far better understanding of the relationship between exposure and disease.     

Mercury toxicity due to the smelting of placer gold recovered by mercury amalgam

A 19-year-old man developed tremor in both hands and fatigue after starting work at a placer gold mine where he was exposed to mercury-gold amalgam. Examination revealed an intention tremor, dysdiadochokinesis and mild rigidity. The 24-h urinary mercury concentration reached a peak of 715 nmol/l (143 ug/l) shortly before the clinical examination, after which he was removed from working in the gold room [Mercury No. Adverse Effect Level: 250 nmol/l (50 ug/l)]. On review 7 weeks later his tremor had almost resolved and the dysdiadochokinesis and rigidity had gone. The 24-h urinary mercury concentration had fallen to 160 nmol/l (32 ug/l). The principal exposure to mercury was considered to be the smelting of retorted gold with previously unrecognized residual mercury in it. The peak air concentration of mercury vapour during gold smelting was 0.533 mg/m3 (Mercury Vapour ACGIH TLV: 0.05 mg/m3 TWA). Several engineering and procedural controls were instituted. This episode occurred at another mine site, unrelated to Mount Isa Mines Limited.     

How Adults with Acquired Brain Damage Perceive Computer Training as a Rehabilitation Tool: A Focus-group Study

The aim of this study was to explore and describe how adult outpatients with acquired brain damage and referred to occupational therapy perceive computer training with the RehaCom programs, in order to evaluate the method of treatment as a tool in the rehabilitation of persons with cognitive disorders. By using focus-group discussions as a qualitative method of research when analysing the result, five themes with corresponding categories emerged, describing a development of understanding and learning about capacities. Themes describing how the participants could apply strategies to overcome shortcomings in daily occupations and the therapeutic role of the occupational therapist were identified as well. The result shows that a computer training program such as RehaCom can be used as an educational tool, for example, to guide a person who is trying to adopt compensatory strategies to avoid overload by taking pauses. It was found that anything the participants learned was also applicable to occupational performance in daily life.