摘要
肿瘤热疗(Hyperthermia)是一种利用热能引起的生物效应来治疗肿瘤的方法,该技术已在临床治疗中得到较为广泛的应用。在肿瘤热疗中常用的电磁能量有微波、射频和超声波等。其中,微波加热技术过热问题比较少,更安全有效,且具有并发症少、副作用小等优势。而微波热疗的核心问题在于设计辐射效率高且安全的天线。
本文借助于基于时域有限积分(FIT)方法的CST MWS软件,研究、设计和制作了一种适合于局部肿瘤热疗需求的辐射天线,并展开了部分实验研究。论文分为三部分:
第一部分,介绍了微波热疗的作用机理、医用微波辐射天线基本理论及其设计方法,为热疗天线的研制提供了理论依据。
第二部分,设计了用于腔外式辐射的加脊圆波导热疗天线。通过介质填充和口面加载多层介质等方式,优化天线结构,减少天线的能量反射,改善了体模中的电场分布,增加了有效加温深度,提高了天线的辐射效率,并在热疗模型中仿真验证了热疗天线对工作频率的波动和结构参数变化的不敏感性。
第三部分,设计并制作了天线,测量了其阻抗特性。在此基础上搭建了热疗模型,开展了体模实验得到了热疗模型的温升特性,实测数据接近仿真数据,结果表明,所设计的天线满足热疗天线的应用要求。
Hyperthermia has been widely used in tumor cure. It is a tumor therapy which is using biological heat effect. Microwaves, radiofrequency, ultrasonic are commonly used in hyperthermia treatment. Microwave heating technology has less problems of overheat, and is more safety. Furthermore, it has little side effect and other disadvantages. Designing high effective and secure microwave hyperthermia antennas is the key issue for improving of microwave hyperthermia.
In this paper, an antenna for a local tumor hyperthermia is designed using the CAD software CST MWS which is based on Finite Integration Technique. The thesis is composed of three parts.
In the first part, the mechanism of microwave hyperthermia, the basic theory and design methods of microwave medical radiation antennas are introduced, which provided a theoretical foundation for the choice of antenna in microwave hyperthermia field.
In the second part, a ridged circular waveguide is designed as an external radiator. The structure of the antenna is optimized by filling the waveguide with dielectric and loading multilayer dielectric at the radiation surface, which can reduce the reflected energy, make the electric field more concentrated and the increase effective heating depth, as the same time, the radiation efficiency will be improved too. The simulation data shows that the radiation antenna is not sensitive to its working frequency and structure parameters.
In the third part, the process of manufacturing needed antenna is showed, the reflection coefficient of the antenna is measured, and the characteristic of temperature rising is measured by building a hyperthermia model. The results show that the measured data fit close to the simulated data, and it meets the requirement of microwave hyperthermia antenna.
引文
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