聚焦超声换能器的频率和曲率半径对生物学焦域的影响  

Effects of Frequency and Curvature Radius of HIFU Transducer on Biological Focal Region

作　　者：李发琪[1] 张樯[2] 马平[1] 王智彪[1] 白晋[1] 伍烽[1] 冯若[2] 

机构地区：[1]重庆医科大学医学超声工程研究所省部共建国家重点实验室,重庆市400016 [2]南京大学近代声学国家重点实验室声学研究所,南京210093

出　　处：《中国超声医学杂志》2004年第2期157-160,共4页Chinese Journal of Ultrasound in Medicine

基　　金：国家自然科学基金项目资助 (No.30 0 70 2 1 7)

摘　　要：目的　探讨聚焦超声换能器的物理参数——频率 (f)、曲率半径 (R)对生物学焦域的影响 ,为优化设计适合临床应用的聚焦超声换能器提供实验依据。方法　运用 JC- A型 Haifu聚焦超声肿瘤治疗系统 ,使用 3种聚焦超声换能器 ,以一定的超声剂量定点辐照新鲜离体牛肝脏 ,辐照结束后沿凝固性坏死最大面剖开 ,测量生物学焦域的长、短轴和体积。结果　对于任一种聚焦超声换能器 ,辐照深度一定时 ,生物学焦域的体积随换能器辐射声功率、辐照时间的增大而增大。在一定的换能器辐射声功率和辐照时间下 ,辐照深度一定时 ,当聚焦超声换能器其他物理参数固定时 ,生物学焦域的体积随换能器频率的增大而增大 ,而生物学焦域的形态指数随频率的增大而减小 ;而当聚焦超声换能器的其他物理参数固定时 ,生物学焦域的体积和形态指数随透镜曲率半径的增大而增大。结论　生物学焦域除了与声功率、辐照时间、辐照深度以及组织结构、功能状态有关外 ,还与聚焦超声换能器的物理参数如频率 (f)、曲率半径 (R)有关。在临床运用中 ,应根据临床方案优化设计适合临床应用的一定频率 (f)和曲率半径 (R)的聚焦超声换能器。Objective:The biological focal region(BFR) of HIFU(High Intensity Focused Ultrasound,HIFU) was defined as individual ellipsoid-shaped coagulative necroses produced by the ultrasound energy deposition of a single exposure. BFR namely knifepoint of HIFU is the foundation for HIFU ablation of tumor volume. Previous results have shown that for a specific transducer BFR induced by HIFU in specific organ or tissue correlated with corresponding acoustic intensity,exposure time,focal depth,tissue structure and its functional status. How do physical parameters of HIFU transducer(focused by lens) influence BFR when other parameters such as acoustic intensity,exposure time,focal depth,tissue structure and its functional status are fixed? So this paper studied the effects of HIFU transducer with frequency(f) and curvature radius(R) on BFR and attempted to provide experimental basis for optimization designing HIFU transducer adapted to clinic.Methods:Fresh bovine liver was irradiated with different HIFU dosage for HIFU transducer No.1,2,3. The sample was dissected immediately after exposure and the maximal section of coagulative necrosis obtained,and the transverse and lengthways diameters and the volumes of the BFR was determined and compared. The ratio of lengthways and transverse diameters of BFR were calculated and termed as the shape index(K) of BFR.Results:At a constant focal depth,the volume of BFR was increased with the increase of acoustic power and exposure time for anyone HIFU transducer. The volume of BFR was increased with the increase of frequency(f) of HIFU when other parameters were fixed,and increased along with the increase of curvature radius(R) of lens when other parameters were fixed. At a constant focal depth and a fixed acoustic power,the shape index(K) of BFR was decreased along with the increase of exposure time. However,when the frequency was constant,the shape index(K) of BFR was increased with the increase of the curvature radius,where as the curvature radius was constant,the shape index(K) of BFR

关 键 词：聚焦超声换能器 频率 曲率半径 生物学焦域 肿瘤 HIFU技术 

分 类 号：TB552[理学—物理]