HIFU治疗中生物组织对声学焦域及声的非线性影响的研究  

Effect of biologic layered tissue on acoustic focal region and acoustic nonlinearity during HIFU treatment

作　　者：徐遨璇 王月兵 郑慧峰 曹永刚 陈璐 XU Aoxuan;WANG Yuebing;ZHENG Huifeng;CAO Yonggang;CHEN Lu(College of Metrology&Measurement Engineering,China Jiliang University,Hangzhou 310018,Zhejiang,China)

机构地区：[1]中国计量大学计量测试工程学院,浙江杭州310018

出　　处：《声学技术》2020年第6期686-692,共7页Technical Acoustics

基　　金：国家重点研发计划(2016YFF0201006);浙江省自然科学基金(LQ20A040007);浙江省基本科研业务费资助项目(2020YW43)。

摘　　要：生物分层组织是高强度聚焦超声治疗中最常见的声通道组织。通过研究生物组织对声学焦域的影响,可以为高强度聚焦超声(High Intensity Focused Ultrasound,HIFU)治疗安全性和可靠性提供理论依据。基于Westervelt方程,利用频域和时域有限元算法仿真HIFU治疗过程中超声透过分层组织后的焦域变化,并用新鲜离体猪肉组织进行实验验证。结果表明:生物组织声学特性的差异性和结构的不均一性使HIFU的声学焦域位置发生改变,尤其在声焦平面内,相对2.5 mm的焦域宽度,1 mm的偏移量将会对HIFU治疗精准性产生影响;声通道中存在生物组织,超声声束不会发生扩散,没有散焦现象,焦域宽度维持在2.38~2.79 mm范围内;HIFU透射生物组织,声学焦域的非线性有明显的减弱,谐波次数越高,衰减程度越大,实验中基波声衰减值为9.97 dB,二次谐波声衰减值为22.33 dB,三次谐波声衰减值为28.05 dB,四次谐波声衰减值为31.06 dB,五次谐波已衰减消失。Biologic layered tissue is the most common acoustic channel in high intensity focused ultrasound(HIFU)treatment.The effect of biological tissue on acoustic focal region is studied to provide a theoretical basis for the safety and reliability of HIFU treatment.Based on Westervelt equation,the finite element algorithms in frequency domain and time domain are used to simulate the focal region changes when ultrasound penetrates layered tissue during HIFU treatment.And experiments are carried out with fresh pork tissue in vitro.The results show that:The differences in acoustic characteristics and structural heterogeneity of biological tissues change the acoustic focal position of HIFU,especially in the acoustic focal plane,the deviation of 1mm relative to the focal field width of 2.5 mm affects the accuracy of HIFU treatment;when there is biological tissue in the acoustic channel,the ultrasonic beam does not spread,no defocusing phenomenon appears,and the focal width maintains in the range of 2.38-2.79 mm;when HIFU penetrates biological tissue,the nonlinearity of acoustic focal region is obviously weakened;The higher the harmonic order,the greater the attenuation is.In the experiment,the acoustic attenuation values of the fundamental wave,the second harmonic,the third harmonic and the fourth harmonic are 9.97,22.33,28.05 and 31.06 dB respectively,and the fifth harmonic disappears due to severe attenuation.

关 键 词：生物分层组织 高强度聚焦超声 声学焦域 有限元 非线性 

分 类 号：TB559[理学—物理]