相控阵HIFU系统中换能器阵的研制
文献类型：学位论文
| 作者 | 王君琳 |
| 学位类别 | 博士 |
| 答辩日期 | 2009-05-13 |
| 授予单位 | 中国科学院声学研究所 |
| 授予地点 | 声学研究所 |
| 关键词 | 高强聚焦超声 相控阵 凹球面 栅瓣 指向性 相位差 |
| 其他题名 | Study on transducer array of phased-array high intensity focused ultrasound |
| 学位专业 | 信号与信息处理 |
| 中文摘要 | 相控式高强聚焦超声（High Intensity Focused Ultrasound-HIFU）由于具有焦点可以自动控制以及多焦点同时聚焦的特点，使肿瘤治疗手术时间缩短，减轻了病人的痛苦，提高了治疗效率。但是在HIFU手术中，除了要达到高功率的能量聚积，安全性也是非常重要的，不能使正常组织受到损伤，也就是聚焦区域内不能有大的栅瓣出现。本文的核心内容就是研制一套这样的换能器阵：既能提供高强度的功率输出，又要使焦点外的区域内不出现大的能量聚积。论文的主要工作和相关结果如下： 1、 首先介绍了HIFU技术的特点、优势和发展历史以及相控阵HIFU的原理和优势，并根据本文所涉及到的内容，简单介绍了相控HIFU源的分类，阵列设计以及目前主要用的计算方法。 2、 从材料选择、频率确定、阵元形状、大小、间距、数量和排列方式、凹球面尺寸等几个方面出发，确定了一种聚焦结果较好的不规则凹球面阵列，并在此基础上，针对激励信号的不同相位精度和幅值，比较了时间反转法和伪逆矩阵算法的优缺点。 3、 由于阵元尺寸大、发射频率高，导致聚焦声场中的焦点动态移动范围不大。本文分别对凸球面阵元表面涂环氧树脂和平面阵元加铝透镜两种不同方法进行了研究，发现两种方法都能实现对指向性开角进行扩展的目标。 4、 针对锁相环电路初始工作时频率有震荡的特点，提出了一种计算相位差的方法，可以实时显示相位差的变化，根据保持稳定后的数据得到发射和接收信号之间的相位差，获得了相控阵HIFU各阵元的初始相位。 5、 由于阵元尺寸大，且阵元之间的相对位置难以确定，本文采用时间反转法，实现了自适应聚焦，实验结果证明了这种方法的可行性。 |
| 英文摘要 | Ultrasound phased arrays show increasing promise as versatile applicators for hyperthermia therapy applied to deep-seated tumors. Phased arrays can generate complex focal patterns, efficiently raising the temperature inside tumors with electronic scanning. Therefore, the interface between patient and ultrasound applicator is less complex than in mechanical scanning focused systems. However，phased arrays have disadvantages include the unwanted presence of grating lobes and other secondary intensity maxima, which will lead to awful surgery accident in clinic. An ultrasound phased-array system that can not only offer high power but also weaken the unwanted grating lobes will be studied in this paper. The main work and the results are as follows: 1、 This paper introduces the characteristic, predominance, development of high intensity focused ultrasound, especially in phased-array systems. Surrounding with the phased-array system, different sorts of applicators, different distribution of elements and the main calculate methods are presented. 2、 From the material, frequency, shape, size, number of elements, the transducer distribution and the shell size, we find a kind of randomly distributed array with lower grating lobes. We compare the characteristic of this applicator using two different techniques such as the time reversal method and the pseudoinverse pattern synthesis method. 3、 Because of the big size and the high frequency of elements, the focus in focusing plane has small dynamic move range. In order to get broader element direction we study two kinds of ways such as adding Epoxy Resin on the surface of protuberant spherical element and gluing the plane piezoelectric slice with aluminum lens. These two ways all can enlarge the element direction. 4、 Because of the frequency shifting when the phase lock loop is initiated, we present a new algorithm that can compute the phase difference in real time and based on the steady phase difference we get the initial phase of the sources. 5、 Because of the big size and the high frequency of elements, the comparative positions between them are difficult to obtain. Time reversal technique is used to achieve self-adaptive focusing and the experiments show the feasibility of this method. |
| 语种 | 中文 |
| 公开日期 | 2011-05-07 |
| 页码 | 94 |
| 源URL | [http://159.226.59.140/handle/311008/528]  |
| 专题 | 声学研究所_声学所博硕士学位论文_1981-2009博硕士学位论文 |
| 推荐引用方式 GB/T 7714 | 王君琳. 相控阵HIFU系统中换能器阵的研制[D]. 声学研究所. 中国科学院声学研究所. 2009. |
入库方式： OAI收割
来源：声学研究所
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