摘要
脑卒中是致残和致死的首因,经颅脑卒中治疗具有无创和颅内出血风险低等优势,目前经颅聚焦超声治疗血栓性缺血脑卒中时使用参数尚不明确。基于志愿者头颅CT图像和82阵元相控换能器建立三维数值仿真模型,利用时域有限差分法数值解析Westervelt声波非线性传播方程,对0.5~1.0 MHz超声激励频率和输入声功率等参数进行数值仿真筛选。结果表明:频率相同时焦点处形成的负压越大所需输入声功率越大,经颅所需输入声功率约为开颅的1.5倍;频率越高焦域面积越小但焦域处的旁瓣增多;频率相同时经颅和开颅模型的焦域形状和大小相近但经颅时的旁瓣较强;焦点处负压达到具有溶栓效果的-6 MPa和具有显著溶栓效果的-8 MPa时所需声功率随频率的提高先减少后增加且频率为0.8 MHz时最小;辐照时间和占空比对焦点位置和焦域面积没有影响。
Stroke is the leading cause of disability and death. Transcranial stroke treatment has the advantages in noninvasiveness and low risk of intracranial hemorrhage. However, the parameters of transcranial focused ultrasound for the treatment of thrombotic ischemic stroke are still not clear at present. In this paper, a 3-D numerical simulation model is established based on head CT images of volunteers and an 82-element phase-controlled transducers array,and the time-domain finite difference method is used to analyze the Westervelt nonlinear acoustic propagation equation. The parameters such as ultrasonic excitation frequency and input sound power are selected by numerical simulation. The results show that when the frequency is the same, the greater the negative pressure formed at the focus,the greater the required input sound power, and the required input sound power for transcranial model is about 1.5times that for craniotomy;And, the higher the frequency, the smaller the focal area, but the more the side lobes at the focal area. When the frequency is the same, the shape and size of the focal area for transcranial and craniotomy models are similar, but the side lobes for transcranial model are stronger. When the negative pressure formed at the focus reaches-6 MPa with thrombolytic effect and-8 MPa with significant thrombolytic effect, the required sound power first decreases and then increases with the increase of frequency, and the minimum appears at 0.8 MHz;Irradiation time and duty cycle have no effect on focal position and focal area.
作者
孙天宇
张艳秋
潘婷
张默涵
凌子超
菅喜岐
SUN Tianyu;ZHANG Yanqiu;PAN Ting;ZHANG Mohan;LING Zichao;JIAN Xiqi(Department of Biomedical Engineering and Technology,Tianjin Medical University,Tianjin 300070,China)
出处
《声学技术》
CSCD
北大核心
2022年第5期664-669,共6页
Technical Acoustics
关键词
经颅
超声溶栓
聚焦超声
数值仿真
transcranial
ultrasonic thrombolysis
focused ultrasound
numerical simulation
