基于激光激发声表面波光谱技术检测人体皮肤病变的研究

发布时间：2018-01-09 22:11

本文关键词：基于激光激发声表面波光谱技术检测人体皮肤病变的研究　出处：《天津大学》2014年硕士论文　论文类型：学位论文

【摘要】：在医学界，皮肤疾病的检测和治疗在很大程度上依靠皮肤科医生的视觉判断。一个皮肤科医生的培养需要多年的培训和临床经验，然而即使如此，有些情况下视觉判断仍无法给出准确定量的信息。因此，通过一种能够准确的检测皮肤疾病的方法来避免模棱两可的判断显得尤为重要。本课题的主要研究目的是开发一种应用激光声表面波的新型非破坏式检测系统以实现对皮肤病变的快速检测，通过应用激光激发声表面波的传播特性来检测皮肤各层的特性以及探测皮肤各层发生的机械和几何变化以判断皮肤病变。与传统超声检测方式不同，激光超声检测法采用脉冲激光光束作为非接触式激发光源在皮肤表面产生声表面波。当一个样品表面被一个高频的激光脉冲照射，由于吸收激光辐射，在局部产生热膨胀，进而产生了声表面波并沿样品表面传播。激光激发声表面波的特性很大程度上取决于激光光束的光学穿透和产生的热扩散、待测材料的弹性参数和几何特征。激光激发声表面波检测方法最大的优势在于无损激发，与检测材料不发生物理接触。本课题通过应用有限元仿真技术来理解和分析激光源与皮肤组织之间相互作用，产生声表面波的原理以及波传播过程中受到的影响和产生的变化，同时深入分析了皮肤病变尺寸不同和网格大小划分不同对仿真结果的影响。本课题的主要研究工作有：介绍了人体皮肤以及皮肤各组成结构的特性，，分析了一些皮肤病变给皮肤机械和几何参数带来的变化。简要介绍了激光激发声表面波理论和声表面波在样品上传播的原理，讨论如何模拟激光激发声表面波及其传播过程。概述有限元建模原理和用于模拟激光激发声表面波以及在表面传播过程的仿真步骤。介绍了理想人体皮肤的模型的建模，并利用激光激发声表面波去检测人体皮肤模型各层机械和几何变化以判断皮肤疾病。用Matlab程序对有限元模拟得到的结果进行数字信号处理，计算出声表面波色散曲线。通过对比色散曲线的变化判断出该检测方法能检测到的最小的皮肤肿瘤尺寸为0.03mm，以及划分网格尺寸对仿真结果的影响。最后提出了应用激光激发声表面波检测皮肤疾病的总结与展望。
[Abstract]:In medicine, the detection and treatment of skin diseases depend largely on the visual judgment of dermatologists. The cultivation of a dermatologist requires years of training and clinical experience, but even so. In some cases, visual judgment still can not give accurate quantitative information. Therefore, it is very important to avoid ambiguity through a method that can accurately detect skin diseases. The main purpose of this paper is to develop a new type of non-destructive detection system using laser surface acoustic wave (LSAW) to detect skin lesions quickly. The characteristics of each layer of skin and the mechanical and geometric changes of each layer of skin were detected by using the propagation characteristics of surface acoustic wave (saw) excited by laser to judge the skin lesions. Different from the traditional ultrasonic detection method, the laser ultrasonic detection method uses pulsed laser beam as a non-contact excitation light source to produce saw on the skin surface, when a sample surface is irradiated by a high-frequency laser pulse. Because of the absorption of laser radiation, local thermal expansion is produced. Then the surface acoustic wave is produced and propagated along the surface of the sample. The characteristics of the surface acoustic wave excited by the laser depend to a great extent on the optical penetration of the laser beam and the thermal diffusion produced by the laser beam. The biggest advantage of the laser-excited saw detection method lies in the nondestructive excitation, and there is no physical contact with the tested material. In this paper, finite element simulation technology is used to understand and analyze the interaction between laser source and skin tissue, the principle of surface acoustic wave (saw) generation, and the influence and change of wave propagation. At the same time, the effects of different skin lesion size and mesh size on the simulation results are analyzed. The main research work of this thesis is as follows: the characteristics of human skin and the structure of skin are introduced. The changes of skin mechanical and geometric parameters caused by some skin lesions are analyzed. The theory of surface acoustic wave excited by laser and the principle of surface acoustic wave propagating on the sample are briefly introduced. This paper discusses how to simulate laser-induced saw and its propagation process. The principle of finite element modeling and the simulation steps used to simulate laser-induced saw and its propagation on the surface are summarized. The model of ideal human skin is introduced. Modeling. The surface acoustic wave (saw) was used to detect the mechanical and geometric changes of human skin model in order to judge the skin disease. The results of finite element simulation were processed by Matlab program. The surface acoustic wave dispersion curve was calculated and the smallest skin tumor size detected by this method was 0.03mm by comparing the dispersion curve. The effect of mesh size on the simulation results is also discussed. Finally, the application of laser-excited saw to detect skin diseases is summarized and prospected.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：R318.51;TN249

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