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1、成都理工大学硕士学位论文基于人机界面的伽玛刀剂量仪的实现姓名:张正为申请学位级别:硕士专业:测试计量技术及仪器指导教师:侯新生20100501基于人机界面的伽玛刀剂量仪的实现 作者简介:张正为,男,1986 年 11 月生,师从于成都理工大学侯新生教授,2010 年 6 月毕业于成都理工大学测试计量技术及仪器专业,获得工学硕士学位。 摘摘 要要 “伽玛刀”名为“刀”,但实际上并不是真正的手术刀,它是一个布满准直器的半球形头盔,头盔内能射出 201 条60Co高剂量的离子射线-伽玛射线。它经过 CT 和磁共振等现代影像技术精确地定位于某一部位, 我们称之为“靶点”。它的定位准确,误差常小于 0.
2、5 毫米;每条伽玛射线剂量梯度极大,对组织几乎没有损伤。但 201 条射线从不同位置聚集在一起可致死地摧毁靶点组织。它因功能尤如一把手术刀而得名,有无创伤、不需要全麻、不开刀、不出血和无感染等优点。伽玛刀剂量如果太小则无法完全去除病灶,达不到治疗效果,过大则可能危及病人的生命。因此伽玛刀剂量与患者健康紧密关联,对于伽玛刀剂量的检测具有十分重要的意义。 近年来国内外伽玛刀设备日益增多, 由于其辐射场的剂量分布曲线边缘变化十分陡峭,而形成焦点的射束是由各方向入射等特点,因而对于伽玛刀的焦点处的剂量率等剂量学参数的测量,要求剂量仪的探头直径(灵敏区)小于2mm、方向性好、灵敏度稳定可靠,所以通常放疗
3、的测量仪器不太适合伽玛刀的测量。拥有伽玛刀的医院,基本靠伽玛刀生产厂家在调试伽玛刀时所测量的剂量学参数(或由拥有伽玛刀的医院聘请国内有关的专家进行测量)输入治疗计划系统,以便治疗中使用,绝大多数医院在以后伽玛刀的使用中,基本无能力测量剂量学参数,这显然是不科学的,同时也影响治疗的效果。 首先本设计的功能是为实现快速、精准、显示伽玛刀的当前剂量,采用人机界面使得设计更为人性化、智能化。设计中力求使得响应速度快,测量精度高,并且界面美观,从而达到市场的需求层次。 伽玛刀剂量仪主要围绕三个方面进行: 伽玛刀射线输出量的测量原理和实现途径;探测器性能研究与工作方式选择;数据采集硬件和软件系统。 首先,
4、本研究在文献和市场调研的基础上,确定了总体结构和系统要求。之后通过对不同辐射剂量探测器进行深入比较分析, 立足于诊断剂量检测技术的发展趋势和伽玛刀射线辐射场特性, 确定了以高纯硅工艺制成的 PIN 型硅光电二极管作为半导体辐射探测器5,它灵敏度高、体积小、响应快,不需高压,然后对探测器的各项性能进行了详尽的理论分析和试验研究, 通过60Co放射源研究了其灵敏度、辐射损伤及退火现象等,重点研究了能量响应特性和补偿方法使其满足设计要求,选择了最佳工作方式。并采用 0.6cc 的石墨电离室作为本剂量仪的剂量刻度的探测器,主要是利用了电离室的能量响应高的特性。 伽玛刀剂量仪具有两个测量通道,其中一个通
5、道接半导体探测器,另一个通道接 0.6CC 石墨电离室。除用于伽玛刀和 X 刀小野吸收剂量测量外,还可以用于法定计量部门对放疗设备的检定和医院放疗吸收剂量的日常监测。 智能化,人性化与直观化是这个研究的主题目标。采用人机界面使设计出来的伽马刀剂量仪不仅在外观上更简约,美观,而且在使用操作上可以更加的方便直观。伽马刀剂量仪能够直观的显示伽马刀的当前剂量,并且它的人机界面设计,使得操作更加的人性化,智能化。 采用半导体探头作为辐射探测器,将辐射信号转化成微弱电流,前置级对微弱信号进行积分,定时测量出电压值,此电压值正比于剂量值。 主板以单片机为核心,在其外部扩展了ADC ,显示模块, 2E PRO
6、M ,打印机、 键盘等,具有数据处理、显示、储存、打印、报警值设置、校正系数设置、测量时间设置以及报警等功能。 基于人机界面的伽玛刀剂量仪主要功能组成部分包括探测器前端电路(前置积分、后级放大及 A/D 转换电路) ,单片机控制电路,以及人机界面三部分。探测器前端电路主要实现将射线强度转换为数字信号。单片机控制电路是整个仪器的控制核心,起到接收与发送信息的作用。人机界面是仪器与人之间传送信息的纽带,它使得操作更加直观、人性化。 该伽玛刀剂量仪主要用于“ 辐射头部立体定向放射外科治疗辐射源”5(又称伽玛刀)的小野(小于18 18mm的野)焦点吸收剂量的测量。它是伽玛刀治疗中日常监测和依据辐射头部
7、立体定向放射外科治疗辐射源检定规程进行定期检定的必备仪器。 关键词:伽玛刀 剂量仪 人机界面 PIN 型硅光电二极管 The realization of gamma knife dosimeter which is based on Man-machine interface Introduction of the author: Zhang Zheng wei, male, was born in November 1986 whose tutor was Professor Hou Xin sheng . He graduated from Chengdu University of T
8、echnology in Measurement technology and instruments major and was granted the Master Degree in June, 2010 Abstract “Gamma Knife“ is called “knife“, but in fact it is no real scalpel, it is a device filled with quasi-hemispherical straight helmet, 201 beams of 60 high-dose cobalt ion ray can be fired
9、 in the helmet - gamma rays.Through CT and MRI of the modern imaging technology ,it can accurately locate a particular area, we call it “target.“ It is extremely accurate positioning, the error is usually less than 0.5 mm; each dose of gamma-ray has a great gradient, there is almost no damage to the
10、 organization. But the 201 rays come together from different locations can be lethal to destroy the target tissue. Its functions just like a scalpel because of its name.There are advantages just like no trauma, no anesthesia, no surgery, no bleeding and no infection and so on. The lesion can not be
11、completely removed if the dose of Gamma Knife is too less, then its not effective, if the does is too more it may endanger the patients life. Therefore the dose of Gamma Knife is closely related to patients health, the detection of gamma knife dose is of great significance. The equipments of Gamma K
12、nife are increasing at home and abroad in recent years, due to its marginal changes in the distribution curve of the dose of radiation field is very steep, the direction of the beam which is formed by the the focus is incident and so on, so Therefore the focus of Department for Gamma Knife dose rate
13、 of measured dose parameters, required dosimeter probe diameter (sensitive area) which is less than 2mm, directional, sensitive and reliable, therefore radiation measuring instruments are usually not suitable for measurement of gamma knife. The hospital which has a Gamma Knife, is mainly helped by k
14、nife manufacturers in debugging when measured gamma knife dose parameters (or Gamma Knife Hospital has hired national experts in the measurement) input treatment planning system for the treatment of the use of the vast majority of hospitals in the use of Gamma Knife in the future, no ability to meas
15、ure the basic dosimetric parameters, which is obviously not scientific, but also affect the effectiveness of therapy. First of all, this design feature is the fast, accurate display of the current dose of gamma knife, using man-machine interface makes the design more humane and intelligent. Design s
16、eeks to make fast response, high accuracy, and attractive interface to achieve the demand of the market. Gamma dosimeter mainly focused on three aspects: the measurement principle of Gamma-ray output and implementation approach; Detector research and work options; data acquisition hardware and software systems. First, this study has determined the overall structure and system requirements in the literature and on the basis of market research. After the rad