Liu Hao-Li, Chen Heng-Wen, Kuo Zhen-Hao, Huang Wen-Cheng
Department of Electrical Engineering, and the Biomedical Engineering Center, Chang-Gung University, Taoyuan 333, Taiwan, R.O.C.
IEEE Trans Biomed Eng. 2008 Oct;55(10):2407-16. doi: 10.1109/TBME.2008.925697.
The purpose of this paper is to demonstrate a prototype design of a low-frequency multiple-channel hemispherical focused-ultrasound phased-array system for transcranial disruption of the blood-brain barrier (BBB). A 32-channel ultrasound driving system tunable in the frequency range from 200 to 400 kHz was designed for producing a suitable ultrasound output for BBB disruption. The driving system includes a microcontroller/field-programmable gate-array-based control kernel with multiple-channel driving circuits implemented by a high-voltage switching/LC-resonance/impedance-matching circuit module. Three hemispherical phased arrays comprising 22, 31, and 80 elements were fabricated and tested. The pressure distributions at the geometric center and at off-center positions were tested experimentally. The focal performance of the different hemispherical arrays was also evaluated theoretically. The results showed that the developed phased-array system can successfully drive the hemispherical array with multiple-channel ultrasound signals with independent phase control at 8-bit resolution. Good focusing abilities were evident both at the geometric center and at specific off-center target positions. Preliminary animal experiments show that the BBB in rat can be locally disrupted successfully. The system will serve as a reference platform for developing a focused-ultrasound system for clinical use in brain drug delivery applications.
本文的目的是展示一种用于经颅破坏血脑屏障（BBB）的低频多通道半球形聚焦超声相控阵系统的原型设计。设计了一种在200至400kHz频率范围内可调的32通道超声驱动系统，以产生适合破坏血脑屏障的超声输出。该驱动系统包括一个基于微控制器/现场可编程门阵列的控制内核，以及由高压开关/LC谐振/阻抗匹配电路模块实现的多通道驱动电路。制作并测试了由22、31和80个元件组成的三个半球形相控阵。对几何中心和偏心位置的压力分布进行了实验测试。还从理论上评估了不同半球形阵列的聚焦性能。结果表明，所开发的相控阵系统能够以8位分辨率独立相位控制，成功地用多通道超声信号驱动半球形阵列。在几何中心和特定偏心目标位置均表现出良好的聚焦能力。初步动物实验表明，大鼠的血脑屏障能够被成功地局部破坏。该系统将作为一个参考平台，用于开发用于脑内药物递送应用的临床聚焦超声系统。
