中文摘要：

为了确保超声热疗与高强度聚焦超声的疗效,需要严格控制温度,因此在治疗的温度测量是必要的.热电偶通常用于临床热疗,虽然它是一个高准确的技术,但需要插入器官,这给病人带来痛苦,因此没有被广泛使用.已提出一些无损测量温度的方法,如电阻抗断层成像,X-CT,磁共振成像,超声,微波,热温度补偿方法和计算机模拟,其中的温度场的计算机模拟是Pennes生物热方程,考虑血流量,超声波源的强度和测量的皮肤外的温度.由于生物组织是多层结构,其形状是不规则的,因此必须采用数值方法来获得组织的温度场分布.在本文中,首先,采用Khokhlov-Zabolotaskaya-Kuznetsov（KZK）方程用于多层组织的声场分布,用有限元软件求解Pennes方程,获得多层组织在不同条件下的轴向温度分布.实验结果与理论对比表明实验和理论符合得很好.当样品厚度增加,部分能量被前部的组织吸收,因此焦点处将得到较少的能量,最高温度升高会降低,最高温度的位置也将向后移动.在增加换能器表面声压时,样品的最高温度的升高也将增加,但最高温度的位置保持不变,因此,换能器的表面声压对温度场有很大的影响.样品向后移动时,更少的能量将由前部的组织吸收,所以焦点将获得更多的能量,最高温度升高会增加,最高温度的位置也将向前移动.对于两层组织（脂肪-肝）和三层组织（脂肪-肌肉-肝脏）,一部分能量被脂肪和肌肉所吸收,更少的能量在焦点被吸收,最高温度升高也将下降,最高温度的位置也将向后移动.研究表明,厚度和组织参数对热疗有非常重要的影响,在超声热疗中必须考虑在内.本研究结果将对超声热疗提供有用的信息.

英文摘要：

In order to ensure the efficacy of ultrasound hyperthermia and HIFU,it is needed to control the temperature,therefore the temperature measurement in the treatment is necessary.Thermocouple is often used in clinical hyperthermia.Although it is a high accurate technique,it is needed to insert into the organ,which gives the patient pain,and therefore is not widely used.This non-destructive temperature measurement methods have been proposed,such as electrical impedance tomography,X-CT,MRI imaging,ultrasound,microwave,hot temperature compensation method and computer simulation,in which a computer simulation of temperature field is based on the Pennes bio-heat equation,considering the blood flow,the ultrasonic source strength and the measured temperature outside the skin.Because the biological tissues are multi-layer structures and their shapes are irregular,therefore the numerical method must be used to obtain the temperature field distribution.In this paper,firstly,Khokhlov-Zabolotaskaya-Kuznetsov（KZK） equation is used to get the sound field distribution of multi-layer tissue,a finite element software is used to calculate the Pennes equation,and axial-temperature distribution for multi-layer tissues is obtained under different conditions.The experimental results are compared with theoretical prediction and show that the experiments fit the theoretical results well.When the thickness of samples increase,a part of energy is absorbed by the anterior part of tissue compared with before,so the focus will get less energy,and the maximum temperature elevation will decrease,and the position of maximum temperature will also move backward.When the sound pressure at the surface of the transducer increase,the maximum temperature elevation of the sample will also increase,but the position of maximum temperature remain the same,therefore,the sound pressure at the surface of the transducer has a great influence on the temperature field.When the samples move backward,less energy will be absorbed by the anterior part of tissue,so