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 clement 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 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 the focus will get more energy, and the maximum temperature elevation will increase,and the position of maximum temperature will also move forward. For two-layer tissue(fat- liver) and threrlaycr tissue(fat-muscle-liver),a part of energy is absorbed by fat sample and muscle sample,less energy will be absorbed at the focus, and themaximum temperature elevation will decrease, and the position of maximum temperature will also move backward. Our research show that the influence of the thickness and tissue parameters are very important to the hyperthermia,they must be taken into consideration during the hyperthermia with ultrasound. We hope our study can provide some useful information for the hyperthermia.
Zhang Fei ,Liu Xiao Zhou**,Gong Xiu- Fen.
Study of the temperature field in multilayer biological tissue using finite element method*[J]. Journal of Nanjing University(Natural Sciences), 2012, 48(5): 572-581
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参考文献
[1]Feng R.China focused ultrasound technology, the rapid rise and prospects. Acoustics technol ogy, 2011,30(1):17一20. [2]Feng R. High-strength focused ultrasound( HIFU) norrinvasivc surgery一the 21st century, a new cancer treatment technology.Acoustics. 2001,20(2):38一42. [3]Feng R,Zhang Q, Li F Q, et al. Study of the dosage of high intensity focused ultrasound trea- ting tumors. Journal of Nanjing University ( Natural Sciences),2011,47(2),141一146. (冯若,张墙,李发琪等,高强聚焦超声治疗肿瘤的剂量学研究.南京大学学报(自然科学),2011 , 47(2),141一146). [4]Jiang X T,Xi Q J. High intensity focused ul- trasound technology development and applica- tion.The international Journal of Biomedical Engineering, 2006,29(6):379一381. [5]Sun F C,Tang J M. Higlrintensity focused ul trasound in the field of medical ultrasound in the development and application. Physics, 2007,36 (9):708一714. [6]EAZabolotskaya R. Quasi-plane waves in the nonlinear acoustics of confined beams. Soviet Physics Acoust,1969,15:35一40. [7]Kuznctsov V P. Equations of nonlinear acous tics. Soviet Physics Acoust,1971,16: 467一470. [8]Khokhlova V A,Souchon R,J.TavakkoliJ,et al. Numerical modeling of finitramplitude sound beams:Shock formation in the near field of a cw plane piston source. Journal of the A- coustical Society of America, 2001,110: 95一108. [9]Pennes H H. Analysis of tissue and arterial blood temperatures in the resting human fore- arm. Apply Physiology, 1948,1:9一122. [10]Karaa S, Zhang J,Yang F Q, et al. A numerical study of a 3D biohcat transfer problem with dif- ferent spatial heating. Mathematics and Com- puters in Simulation, 2005,68(4):375一388. [11]Samaras T,Christ A,Kustcr N, et al. Physics in Medicine and Biology, 2006,51(11):N221. [12]Ma H,Wang G. COMSOL Multiphysics basic operating instructions and FAQs. Beijing, Peo- ple’s Communications Press,2009,10.(马 慧,土刚.COMSOL Multiphysics 基木操作指南和常见问题解答.北京:人民交通出版社,2009,10). [13]Lang J,Erdmann B, Seebass M, impact of non linear heat transfer on temperature control in re gional hyperthermia. IEEE Transactions on Bio medical Engineering, 1999,46(9) 1129一1138.
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脚注
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基金
National Basic Research Program of China (2012CB921504, 2011CB707902),National Natural Science Foundation of China(11274166),State Key Laboratory o1 Acoustics, Chinese Academy o1 Sciences (SKLA201207)