注入电流式磁声耦合成像实验研究

发布时间：2018-03-30 16:39

本文选题：注入式　切入点：磁声耦合　出处：《北京协和医学院》2012年硕士论文

【摘要】：长期以来,生物组织电特性研究引起了多个领域专家的广泛关注。研究显示,不仅生物组织电特性差异大,且组织和器官的电特性随其功能状态而改变,故组织电特性成像可反映人体生理、病理状态及其变化。利用无损技术检测生物组织的电特性对临床诊断,尤其是癌症的早期诊断具有重要意义。注入式磁声耦合成像是对组织电特性无损检测的一种方法,其原理为将被测生物组织置于稳恒磁场中,并对其施加脉冲电场,组织内的离子在正交的磁场和电场作用下将受到洛伦兹力作用,力致振动发射声波,在组织周围放置声传感器检测声响应信号即可了解组织内部的电特性信息。本文旨在对注入式磁声耦合成像进行简单模型仿真和实验研究。在仿真研究中分别建立了圆形环、同心圆环、有孔圆片模型,借助有限元分析软件仿真模型中施加于其上的电流密度分布,并计算求得声振动源分布及空间声场分布。实验研究中,本文首先对不同激励脉冲作用下产生的磁声信号进行研究,选定正弦脉冲信号为实验研究的激励信号。当探头在某一位置沿不同角度采集磁声信号时,信号强度存在差异,探头旋转一定角度后信号较为微弱。对不同形状模型下产生的声信号进行检测和分析,证明了磁声耦合效应用于组织电特性成像的可行性。选用电特性与生物组织接近的凝胶作为实验对象,产生的声信号较为微弱但可反映出样本边界信息。声信号采集实验中信号频段为1MHz量级,能有效避免外界低频噪声干扰,信号的信噪比较高。在成像实验研究中,通过旋转探头和沿圆周运动扫描样本采集数据,用直接反投影方法重建图像可以反映出样本的基本形状。本文通过不同实验模型对磁声耦合成像进行声信号检测及初步成像研究,取得较好实验结果,对磁声耦合成像的深入研究也具有重要意义。
[Abstract]:For a long time, the study of electrical properties of biological tissue has attracted wide attention of many experts.Nondestructive detection of electrical properties of biological tissues is of great significance for clinical diagnosis, especially for early diagnosis of cancer.Injection magnetoacoustic coupling imaging is a method for nondestructive detection of the electrical properties of tissues. The principle is to place the tested biological tissue in a steady magnetic field and to apply a pulsed electric field to it.The ions in the tissue will be subjected to Lorentz force under the action of orthogonal magnetic field and electric field. The acoustic response signals can be detected by placing sound sensors around the tissue to understand the electrical characteristics of the tissue.In this paper, the simple model simulation and experimental study of injection magnetoacoustic coupling imaging are carried out.In the simulation research, the circular ring, the concentric ring and the perforated disk model are established respectively. The distribution of the current density applied to the circular ring, the concentric ring and the perforated circular ring is obtained by means of the finite element analysis software, and the distribution of the acoustic vibration source and the spatial sound field are obtained by means of the finite element analysis software.In the experimental research, the magnetoacoustic signals produced by different excitation pulses are studied firstly, and the sinusoidal pulse signals are selected as the excitation signals in the experiment.When the probe collects the magnetoacoustic signal at different angles at a certain position, the signal intensity is different, and the signal is weak after the probe rotates at a certain angle.The acoustic signals generated by different shape models are detected and analyzed, which proves the feasibility of magnetoacoustic coupling effect in the imaging of tissue electrical characteristics.The gel which is close to the biological tissue is chosen as the experimental object. The acoustic signal produced is weak but it can reflect the sample boundary information.In the acoustic signal acquisition experiment, the signal frequency band is of the order of 1MHz, which can effectively avoid the external low-frequency noise interference, and the signal-to-noise ratio of the signal is high.In this paper, the sound signal detection and preliminary imaging of magnetoacoustic coupling imaging are studied by different experimental models, and good experimental results are obtained, which is also of great significance to the further study of magnetoacoustic coupling imaging.
【学位授予单位】：北京协和医学院
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：R310

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