基于声换能器特性的磁感应磁声成像正问题分析

Forward problem of magnetoacoustic tomography with magnetic induction based on the characteristics of acoustic transducer

目的在考虑声换能器特性的基础上,对磁感应磁声成像的正问题进行研究,并探讨其声源的产生、传播及接收机制。方法参考CT的三维Phantom仿真模型建立磁感应磁声成像正问题的模型,并结合电磁场理论利用有限元软件comsol仿真分析模型内部电导率分布与磁场和磁感应电场的关系,得到模型内部的磁感应电流分布。然后再深入研究声偶极子模型,并检测分析声换能器的特性后,给出相应的仿真声信号检测结果。结果磁感应电流密度在中心位置处为0,在电导率边界处变化较大,声换能器的检测声场分布和声偶极子传播的指向性会极大的影响声换能器接收到的磁声信号的值。结论为磁感应磁声成像实验研究及由声信号重建物体内部的电导率分布提供理论基础。

Objective To investigate the forward problem of magnetoacoustic tomography with magnetic induction（MAT-MI）,and explore the generation and transmission mechanisms of acoustic source on the basis of acoustic transducer characteristics.Methods A simulation model of MAT-MI was established according to the three-dimensional CT Phantom.The relationship between the induced electric field and the conductivity inside model were conducted with the model in combination with the electromagnetic theory and finite element analysis.The acoustic dipole model was then adopted,the characteristics of the acoustic transducer were detected,and simulation of acoustic signal was implemented.Results The simulation result showed that the induced current was 0 at the centre and varied significantly at the boundary of different conductivity.The signal received by the acoustic transducer was deeply affected by the acoustic pressure field distribution of acoustic transducer and the directivity of acoustic dipole.Conclusion The presented study provides a basis for the experimental study on MAT-MI and the reconstruction of conductivity distribution.