基于声偶极辐射的磁感应磁声层析成像研究

基于声偶极辐射模型提出磁感应磁声层析成像理论来解决点声源理论所不能解释的边界信号和反相振动问题,理论分析了洛伦茨力引起的一维组织振动和自由空间的三维声偶极辐射,推导了磁声激发、磁声衍射传播和换能器磁声波形接收的解析公式。对二层柱状组织模型进行的数值模拟和实验测量结果证明声偶极传播的指向性会使磁声信号在不同传播方向上产生衰减,接收到的磁声波形在声压突变处产生反映电阻抗分布边界信息的脉冲串,重构的层析图像显示不同电阻抗组织的外形和尺寸。本研究为磁感应磁声层析成像技术在医学成像中组织电阻抗分布的重建提供了理论基础。

Investigation of magnetoacoustic tomography with magnetic induction based on acoustic dipole radiation

Based on the acoustic dipole radiation model,a new theory for Magnetoacoustic Tomography with Magnetic Induction(MAT-MI) is proposed in the paper to solve the problem of opposite acoustic vibration at the conductivity boundary.The analytic solutions of magnetoacoustic transmission and acoustic waveform collection are deduced for one dimensional vibration and three dimensional acoustic dipole radiation.The simulation results prove that the acoustic wave clusters comprise the conductivity information and the reconstructed tomographic image can present the configurations of conductive tissues without inner conductivity distribution visualization.The experimental results have good agreements with the theoretical simulations for a two layer cylindrical phantom model.The favorable results of the proposed theory provide a basis for the feasible application of MAT-MI in bio-electrical impedance imaging.