高强度聚焦超声声场的时域有限差分法仿真研究
发布时间：2018-11-06 20:45
【摘要】：目的：高强度聚焦超声(High-intensity Focused Ultrasound, HIFU)治疗技术具有非侵入性、微创伤等优点,已成为众多研究者关注和研究的热点,并应用于体外冲击波碎石疗法(Extracorporeal shock wave lithotripisy, ESWL)、HIFU肿瘤治疗等临床治疗之中。但这些治疗中都有可能引发并发症,如体外冲击波碎石治疗中可能出现尿血、肾血肿、肾破裂等,HIFU肿瘤治疗中可能引起皮肤烧伤、神经损伤等对人体正常组织的伤害。影响HIFU疗法疗效和引发这些并发症的主要因素之一为高强度超声波聚焦传播过程中,在人体内形成的焦点区域位置、形状、大小、声压分布和焦点前浅层区域能量分布。研究HIFU治疗中形成的焦点区域、能量密度分布及人体组织对焦点区域声压、实际形成焦点位置的影响,为ESWL治疗计划的制定提供理论依据；研究降低焦点前非靶区能量密度和提高聚焦效率的聚焦方法,为目前ESWL治疗、HIFU肿瘤治疗中对人体正常组织伤害的解决提供新途径和方法。 方法：森田长吉等人提出了时域有限差分(Finite Difference Time Domain, FDTD)超声波非线性传播的仿真方法,并以Reichenberger的ESWL水中实验为例,对水体内高强度超声波非线性传播进行了仿真研究,得到了与实验测得波形完全一致的仿真结果。 本论文利用森田长吉等人提出的高强度超声波非线性传播的FDTD仿真方法,以Reichenberger的ESWL水中实验为例,(1)参照实际人体组织结构建立单一人体组织和复合人体组织仿真模型,研究ESWL治疗过程中超声波在人体组织内非线性传播特性和人体组织对超声波聚焦传播所形成的焦点区域位置、大小、形状、声压分布影响。(2)研究解决ESWL治疗和HIFU肿瘤治疗过程中并发症问题,应用FDTD仿真的方法,研究并提出一种可以减小浅层区域能量密度和提高超声能量向焦点聚焦效果的新型相位控制圆环状聚焦方法。结果：1.以Reichenberger的ESWL水中实验为例,建立水体仿真模型进行仿真,仿真得到ESWL治疗中在三维空间上所形成的焦点区域近似为橄榄球体,但其所形成的焦距(最大声压位置)与设备的几何焦距并不一致。 2.在Reichenberger水体实验仿真模型的基础上,加一定厚度人体脂肪或肌肉组织建立仿真模型,讨论不同厚度的不同人体组织对所形成焦点区域、最大声压、焦距的影响。仿真结果表明,最大声压随脂肪厚度增厚而增大,随肌肉增厚而减小；焦距随人体脂肪和肌肉厚度增加而减小；形成的橄榄球体状焦点区域的长、短轴长度随脂肪厚度的增厚变小,随肌肉厚度增厚长轴增大,短轴变化不大。 3.参照ESWL临床治疗时B超图像显示的人体结构层次及厚度,建立包括皮下脂肪、肌肉、肾周脂肪、肾脏的复合人体组织仿真模型,数值仿真ESWL治疗过程中超声波非线性传播过程。仿真结果为焦距为118.94mm,其值小于几何焦距120mm,最大声压34.19MPa,其值小于水中实测声压44.56MPa。 4.提出新型相位控制环状聚焦方法,其FDTD方法数值仿真结果表明,在阵列阵元相同条件下,圆环聚集法在焦点处获得的最大能量密度比相控点聚焦法高大约30%,但焦点前的非靶区域的最大能量密度相同；如在焦点处获得的最大能量密度相同的条件下,圆环聚集法在焦点前的断面上的最大能量密度比点聚焦下降大约10%。 结论：本论文的仿真研究是以Reichenberger水中实验为例建立水体模型和含有人体组织的模型,利用FDTD法数值仿真法研究了高强度聚焦超声治疗过程中的所形成焦点区域以及最大声压、焦点位置,焦点区域的大小以及随人体组织厚度变化的规律,为ESWL临床治疗计划的制定提供理论依据；同时提出了一种可以降低焦点前非靶区能量密度和提高聚焦效率的圆环状聚焦方法,改聚焦方法的提出为目前ESWL治疗、HIFU肿瘤治疗中对人体正常组织伤害的解决提供新途径和方法。本研究建立的仿真模型,仅以规则无方向性差异组织的设定条件下进行仿真研究,与实际人体组织结构、组织的特性仍有一定差异,实际人体组织结构、组织特性的三维模型有待进一步仿真研究。
[Abstract]:Objective: The high-intensity focused ultrasound (HIFU) treatment technology has the advantages of non-invasive, microtrauma and so on. It has become the focus of many researchers' attention and research, and is applied to the clinical treatment of extracorporeal shock wave lithotripsy (ESWL) and HIFU tumor treatment. However, there are possible complications in these treatment, such as the possibility of urine blood, renal hematoma, and kidney rupture in the treatment of extracorporeal shock wave lithotripsy. In the treatment of HIFU tumor, the injury to the normal tissues of the human body can be caused by skin burn, nerve injury and the like. The focus area, shape, size, sound pressure distribution and the energy distribution of the shallow area in the focal area, which are formed in the human body, are the main factors that affect the curative effect of the HIFU therapy and the complications. The focus area, energy density distribution and the influence of human body tissue on the focal area sound pressure and the actual focus position were studied in the study of HIFU treatment, and the theoretical basis for the development of the ESWL treatment plan was provided. The focus of the energy density and the focusing efficiency of the non-target area before the focus was studied. The invention provides a new way and a method for solving the normal tissue injury of the human body in the treatment of the ESWL and the treatment of the HIFU tumor. Methods: The finite difference time domain (FDTD) method for nonlinear propagation of the time domain was proposed, and the nonlinear propagation of high-intensity ultrasonic waves in water was simulated with the experiment of Reichenberger's ESWL water. The simulation of the waveform is obtained in the same way as the measured waveform. The results of this paper are as follows: (1) To establish a single body tissue and a compound body group with reference to the actual human tissue structure, using the high-intensity ultrasonic non-linear propagation (FDTD) simulation method proposed by the son Tian Changji, et al., in the case of Reichenberger's ESWL water experiment. In the study of the non-linear propagation characteristics of the ultrasound in the human tissue and the focal region position, size, shape, sound, Effect of pressure distribution. (2) To study the problems of complications during the treatment of ESWL and HIFU, the method of FDTD simulation is applied to study and propose a new phase control ring which can reduce the energy density of the shallow region and improve the focusing effect of ultrasonic energy to the focus. shape-focusing method The results are as follows: 1. The simulation of the water body simulation model is carried out in the ESWL water experiment of Reichenberger, and the focal area formed in the three-dimensional space of the ESWL treatment is approximated as a football body, but the focal length (the maximum sound pressure position) and the geometric focus of the device are obtained. 2. Based on the experimental simulation model of the Reichenberger water body, a simulation model of human body fat or muscle tissue with a certain thickness is added, and different human body tissues with different thicknesses are used for forming the focal area, and the maximum The simulation results show that the maximum sound pressure increases with the thickness of the fat and decreases with the thickening of the muscle; the focal length decreases with the increase of the body fat and the thickness of the muscle; the length of the formed football body-shaped focal area and the length of the short axis vary with the fat The thickening of the thickness of the skin becomes small, and the long axis is increased with the thickness of the muscle. The change of the short axis is not great. 3. With reference to the structure level and thickness of the human body displayed by the B-ultrasound image in the clinical treatment of ESWL, the complex human tissue simulation model including the subcutaneous fat, the muscle, the kidney and the fat and the kidney is established, and the numerical simulation ESWL treatment process The simulation result is that the focal length is 118.94mm, its value is less than 120mm of the geometric focal length and the maximum sound pressure is 340.19MPa, its value is less than that of the water A new phase-controlled cyclic focusing method is proposed. The numerical simulation results of FDTD method show that the maximum energy density obtained at the focal point is the same as the array element. The degree of focus is about 30% higher than the phase control point focus method, but the maximum energy density of the non-target area before the focus is the same; if the maximum energy density obtained at the focal point is the same, the maximum energy of the ring aggregation method on the section before the focus Conclusion: The simulation of this paper is to establish a water body model and a model containing human tissue in Reichenberger's water experiment. The numerical simulation of this paper is used to study the effect of high intensity focused ultrasound in the treatment of high intensity focused ultrasound. The focal area and the maximum sound pressure, the focal position, the size of the focal area and the change of the thickness of the tissue of the human body are formed, and the theoretical basis for the development of the ESWL clinical treatment plan is provided. At the same time, the energy of the non-target area before the focus can be reduced The invention relates to an annular focusing method for improving the density and improving the focusing efficiency, A new approach and a method for solving the problem of normal tissue injury are provided. The simulation model established in the study is only simulated under the set conditions of the regular non-directional difference organization, and the structure of the actual human body and the characteristics of the tissue still have a certain difference, and the actual human body structure and the group
【学位授予单位】：天津医科大学
【学位级别】：硕士
【学位授予年份】：2007
【分类号】：R312
本文编号：2315421
[Abstract]:Objective: The high-intensity focused ultrasound (HIFU) treatment technology has the advantages of non-invasive, microtrauma and so on. It has become the focus of many researchers' attention and research, and is applied to the clinical treatment of extracorporeal shock wave lithotripsy (ESWL) and HIFU tumor treatment. However, there are possible complications in these treatment, such as the possibility of urine blood, renal hematoma, and kidney rupture in the treatment of extracorporeal shock wave lithotripsy. In the treatment of HIFU tumor, the injury to the normal tissues of the human body can be caused by skin burn, nerve injury and the like. The focus area, shape, size, sound pressure distribution and the energy distribution of the shallow area in the focal area, which are formed in the human body, are the main factors that affect the curative effect of the HIFU therapy and the complications. The focus area, energy density distribution and the influence of human body tissue on the focal area sound pressure and the actual focus position were studied in the study of HIFU treatment, and the theoretical basis for the development of the ESWL treatment plan was provided. The focus of the energy density and the focusing efficiency of the non-target area before the focus was studied. The invention provides a new way and a method for solving the normal tissue injury of the human body in the treatment of the ESWL and the treatment of the HIFU tumor. Methods: The finite difference time domain (FDTD) method for nonlinear propagation of the time domain was proposed, and the nonlinear propagation of high-intensity ultrasonic waves in water was simulated with the experiment of Reichenberger's ESWL water. The simulation of the waveform is obtained in the same way as the measured waveform. The results of this paper are as follows: (1) To establish a single body tissue and a compound body group with reference to the actual human tissue structure, using the high-intensity ultrasonic non-linear propagation (FDTD) simulation method proposed by the son Tian Changji, et al., in the case of Reichenberger's ESWL water experiment. In the study of the non-linear propagation characteristics of the ultrasound in the human tissue and the focal region position, size, shape, sound, Effect of pressure distribution. (2) To study the problems of complications during the treatment of ESWL and HIFU, the method of FDTD simulation is applied to study and propose a new phase control ring which can reduce the energy density of the shallow region and improve the focusing effect of ultrasonic energy to the focus. shape-focusing method The results are as follows: 1. The simulation of the water body simulation model is carried out in the ESWL water experiment of Reichenberger, and the focal area formed in the three-dimensional space of the ESWL treatment is approximated as a football body, but the focal length (the maximum sound pressure position) and the geometric focus of the device are obtained. 2. Based on the experimental simulation model of the Reichenberger water body, a simulation model of human body fat or muscle tissue with a certain thickness is added, and different human body tissues with different thicknesses are used for forming the focal area, and the maximum The simulation results show that the maximum sound pressure increases with the thickness of the fat and decreases with the thickening of the muscle; the focal length decreases with the increase of the body fat and the thickness of the muscle; the length of the formed football body-shaped focal area and the length of the short axis vary with the fat The thickening of the thickness of the skin becomes small, and the long axis is increased with the thickness of the muscle. The change of the short axis is not great. 3. With reference to the structure level and thickness of the human body displayed by the B-ultrasound image in the clinical treatment of ESWL, the complex human tissue simulation model including the subcutaneous fat, the muscle, the kidney and the fat and the kidney is established, and the numerical simulation ESWL treatment process The simulation result is that the focal length is 118.94mm, its value is less than 120mm of the geometric focal length and the maximum sound pressure is 340.19MPa, its value is less than that of the water A new phase-controlled cyclic focusing method is proposed. The numerical simulation results of FDTD method show that the maximum energy density obtained at the focal point is the same as the array element. The degree of focus is about 30% higher than the phase control point focus method, but the maximum energy density of the non-target area before the focus is the same; if the maximum energy density obtained at the focal point is the same, the maximum energy of the ring aggregation method on the section before the focus Conclusion: The simulation of this paper is to establish a water body model and a model containing human tissue in Reichenberger's water experiment. The numerical simulation of this paper is used to study the effect of high intensity focused ultrasound in the treatment of high intensity focused ultrasound. The focal area and the maximum sound pressure, the focal position, the size of the focal area and the change of the thickness of the tissue of the human body are formed, and the theoretical basis for the development of the ESWL clinical treatment plan is provided. At the same time, the energy of the non-target area before the focus can be reduced The invention relates to an annular focusing method for improving the density and improving the focusing efficiency, A new approach and a method for solving the problem of normal tissue injury are provided. The simulation model established in the study is only simulated under the set conditions of the regular non-directional difference organization, and the structure of the actual human body and the characteristics of the tissue still have a certain difference, and the actual human body structure and the group
【学位授予单位】：天津医科大学
【学位级别】：硕士
【学位授予年份】：2007
【分类号】：R312
【引证文献】
相关硕士学位论文 前1条
1 张焕春;基于FDTD的黏热流体介质中超声波传播数值仿真[D];青岛大学;2012年
，本文编号：2315421
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