【作者】 马建林；

【导师】 刘波峰；

【作者基本信息】 湖南大学 ， 控制科学与工程， 2009， 硕士

【摘要】 目前乳腺癌的发病率已由女性恶性肿瘤中的第2位跃居到首位,且发病年龄趋于年轻化,乳腺癌对人类健康的严重危害已引起了世界卫生组织和医疗界人士的高度重视。乳腺癌早期发现、早期诊断、早期治疗是降低乳腺癌死亡率的关键。而传统的胶片摄影技术对于致密性乳腺及一致性密度增高病变有明显的局限性。随着计算机技术的发展,数字乳腺X线摄影技术正逐步代替传统的屏片组合,成为临床乳腺癌检查的主要手段。传统乳腺X射线机的工作频率为工频即50Hz,高压发生器及控制系统结构笨重、体积庞大、转换效率低。此外乳腺X射线机是将透视和摄影过程中的电压、电流、时间三个基本参量独立选择和控制,所使用的主要控制元件是多位选择开关、通用继电器和接触器,控制效果差,难以走向小型化、便携化及智能化。本文设计的数字式乳腺X射线机电控系统采用了现代新型的电力电子技术,设备工作频率大幅提高达数十千赫兹,因此减小了铁芯、高压线包的体积,从而减少高压发生器的重量和体积。高压发生器采用了变压器升压结合倍压整流的方式,既获得了输出直流电压的大幅提升又获得了较好的纹波效果。本文提出采用单片机结合脉宽调制技术实现系统的数字控制,由单片机对千伏、毫安实行闭环控制,精心设计了闭环控制系统,稳定性得到提高,高压发生器输出精度得到改善,在保证正常检测的前提下,患者所受X射线剂量降到较低水平。电控系统采用数字信号控制,控制器内结构模块化,保证控制器更轻便、更可靠,实现了电控系统的智能化。最后本文在ORCAD/PSPICE的仿真软件下建立了系统各个主电路部分和控制部分的模型,在分部模型的基础上建立了系统的整体模型,仿真结果分析验证了各部分电路和整体系统的可行性和正确性,为后续的项目研究奠定了基础。更多还原

【Abstract】 At present, the incidence of breast cancer have leapt to the top from the second in women malignant tumor, and tends to younger, the harm of breast cancer to human health has led to the World Health Organization and the medical profession’s high attention. Early detection, early diagnosis, early treatment of breast cancer is the key to reducing breast cancer mortality. Traditional film photography for dense breast and the consistency of dense breast lesions have obvious limitations. With the development of computer technology, digital breast X-ray photographic technique is gradually replacing the traditional film-screen combination has become the mainstream of clinical application.Traditional breast X-ray machine operating frequency are fifty hertz, this will inevitably lead to the structure of its electronic control system cumbersome、bulky、low degree of automation. In addition, the breast X-ray machine independently control three basic parameters of KV or mA or s in the process of perspective and photographic, the main control components are selector switch, general-purpose relays and contactors, control effect is bad, its hard to smaller, portable and intelligent. In this paper, the design of digital electronic control system of breast machine used modern new power electronics technology, operating frequency substantially get to several thousands hertz, therefore reduces the core, the volume of high-tension line package, reduce the weight and size of the high voltage generator. High-voltage generator using a combination of step-up voltage transformer and voltage multiplying rectifier, not only access to the output DC voltage increases and obtain a better ripple effect. In this paper, combined with the use of single-chip and pulse width modulation technology to achieve digital control system, and by the single-chip microcomputer to achieve closed-loop control of KV、mA,well-designed closed-loop control system stability compensation, obtained high-precision control, this will also greatly reduce the volume and weight of high-pressure control devices. Electronic control system used digital signal control, controller with modular structure ensure a more portable, more reliable and achieved intelligent electronic control system.Finally, in ORCAD/PSPICE simulation software to establish a system under the main circuit and control of some part of the model, establish the overall system model on the division model, through the analysis of simulation results to verify the feasibility of various parts of the circuit and the overall system, obtained better results.更多还原