【作者】 高文帅；

【导师】 陈海辉；

【作者基本信息】 南华大学 ， 机械制造及其自动化， 2008， 硕士

【摘要】 1895年伦琴发现X射线,为医学影像学奠定了基础。X射线管经历了离子X射线管、电子X射线管、旋转阳极X射线管三个阶段。随着电力电子技术和微机技术的发展,X射线机正朝着高性能、低成本化的方向发展。高压发生电路从传统的工频(50Hz)向中频(400～20KHz)、高频(20KHz以上)的方向发展,减少了高压发生器体积;控制电路采用了单片机技术,可实现高精度闭环控制管电流、管电压,精确控制曝光时间;采用高频逆变可输出直流的管电压、管电流,减少软X射线对人体的伤害。本文自主研制了高频直流牙科X射线机,高压发生电路频率40 KHz,瞬时功率1600W,输出管电压可在50～100kV范围内调整,输出管电流可在3～8mA范围内调整,功率因数不小于0.92,整机效率不低于90%,球管尺寸小(50×120×125)。该机高频逆变电源采用先进的IGBT开关器件和高频谐振逆变器技术,输出直流管电压、管电流,效率及可靠性极高,阳极高压稳定。采用微处理器控制管电流、管电压。保护措施完善,具有过输入电压、过管电流、过灯丝电流、过功率保护;能自我诊断系统各部分的连接状态,并显示状态。人机界面友好,采用超大汉字或英文液晶显示。多点曝光按键选择,最大限度保证操作者的人身安全与方便。可以采用球管曝光按键近距离曝光、可以采用有线远距离曝光、可以采用远距离红外曝光。另外还设计了运动机架,通过平衡设计使球管能够在拍摄图片时保持静止;通过机械设计保证组合机头在水平面上作360°回转,在垂直面上作大于280°回转,并有分度值为10°指示相对转角的标尺。在底盘配备滚轮,可以移动,便于图像拍摄。共制作了5套样机,进行了电路老化试验、抗干扰试验、介电强度试验,实验结果表明性能优良。样机以每3分钟曝光1次,进行了100小时的连续实验之后,依然可以正常工作。用CCD成像系统可以清晰地看到约20微米的集成电路内部线路,可以清晰地看到牙齿髓腔。用牙科胶片也可以清晰地看到牙齿髓腔。发明一个测量牙科X光机焦皮距的新方法,用牙科X光机拍摄实物,将图像通过CCD图像传感器传输到计算机,经过图像处理软件测量出图像与实物实际尺寸之比,通过相似三角形原理来推导出焦皮距。该方法在放大倍数1.93倍时测得的焦皮距为213mm,只比实际焦皮距205mm多8mm。该方法简易、快速,有实用价值。更多还原

【Abstract】 X-ray was discovered by Roentgen in 1895,which establishes foundation of Medical Imaging.X-ray machine experiences three phase:ion X-ray tube,electron X-ray tube and rotating anode X-ray tube.with the development of power electronic technology and microcomputer technology, the development direction of X-ray machine is high performance and low cost. High voltage generator is processing from power-frequency to middle frequency(400-20KHz)and High Frequency(more than 20KHz),the bulk of high voltage generator is reduced.Control circuit adopts microcomputer technology,high precision close-loop control is used to control tube current and tube voltage,and time of exposure is controlled accurately.High frequency technology was used,direct tube current and tube voltage are acquired and the damage to human is reduced.In this paper,high frequency direct current dental X-ray machine is manufactured,frequency of high-voltage circuit is 40KHz,instantaneous power is 1600W,output tube voltage can be adjusted in 50～100KV,output tube current can be adjusted in3～8mA,power factor is not less than 0.92,the whole efficiency is not less than 90%,tube size is 50×120×125.The high frequency power of this machine adopts advance IGBT switch apparatus and high frequency syntony inverter,dependability of output tube voltage and tube current is high,anode voltage is stable.Microprocessor are used to control tube voltage and tube current.Safeguard is perfect,and it has over input voltage,over tube current,over filament and over power protect;can self-diagnoses the connect station of system parts,and displays the status. Man-machine interface is friendly,and a large liquid crystal display are used to display Chinese characters or English.More spots exposing keys are used to guarantee the personal safety mostly and operating convenience.X-ray exposure can use close tube keys exposure,long-distance cable exposure,and remote infrared exposure.In addition,the movement rack is designed,through the balance design, the assemble head can keep still while shooting pictures;through machinery design,the assemble head can make 360°rotation on the level of the surface, and make 280°rotation on the vertical level,and ruler with 10°degrees value is also designed to show relative rotation;equipped with rollers,the chassis can be fixed and also can be moved,and it is convenient to acquire picture.Five sets of prototype are manufactured,circuit aging test, anti-interference test,dielectric strength test are made,tests results show that performance is excellent.Prototype exposures every three minutes,after 100 hours of continuous experiments,it can still work properly.Using CCD imaging system,the 20μm micron integrated circuits interior lines can be seen clearly,the teeth marrow can be seen clearly.Using dental film,the teeth marrow can also be seen clearly.A new way to measure the focal spot to skin distance of dental X-ray Machine was developed,using dental X-ray machine to get the image of material object,and the image is transmitted to the computer through CCD image sensor,after the measure of image and material object size ratio, through similar Triangle principle to derive the focal spot to skin distance. focal spot to skin distance got by this method is only 8mm longer than the real focal spot to skin distance,which is 205mm.This method is simple,fast,and has practical value.更多还原