注入电流式热声成像方法和实验研究

Imaging Method and Experimental Research on Thermoacoustic Imaging with Current Injection

注入电流式热声成像是一种电磁场与声场耦合新型成像技术,融合了传统电阻抗成像高对比度和超声成像高分辨率的优势,具有早期诊断的潜力。为了提高注入电流式热声成像质量,开展了成像方法和实验研究。分析了注入电流式热声成像方法基本理论。开展了安全性评估,对注入电流式热声成像安全电流及安全热效应进行了评估分析。分析了注入电流式热声成像原理及声源和声场分布特性,以低电导率含电导率异常体模型为例,开展了电磁场和声场耦合分析,得到电场强度及声压的分布情况,给出了热吸收分布、声压随电导率分布变化曲线。同时,在安全性前提下,利用搭建的注入电流式热声成像系统,进行低电导率目标体热声成像研究,开展图像分辨率及电导率分辨能力实验。实验结果表明:注入电流式热声成像分辨率达0.8 mm,电导率分辨能力达0.1 S/m。

Thermo-acoustic imaging with current injection(TAI-CI) is a novel coupling imaging technology with electromagnetic field and sound field, which combines the advantages of high contrast of the electrical impedance tomography and the high spatial resolution of sonography, and has the potential of early diagnosis. In order to improve the image quality of TAI-CI, the imaging method and experimental research are carried out in this paper. The principle of thermo-acoustic imaging with current injection is analyzed. A safety assessment is conducted, and the safety current and safety thermal effect are evaluated and analyzed. The principle of TAI-CI and the characteristics of acoustic source and acoustic field are analyzed. Moreover, by taking the model of low conductivity including abnormal conductivity for example, the coupling analysis of electromagnetic field and acoustic field is carried out, and the distributions of electric field intensity and acoustic pressure are obtained. Meanwhile, the curves of heat absorption distribution and acoustic pressure changing with the conductivity distribution are given. On the premise of safety, the thermoacoustic imaging of low conductivity object is studied by using the system of TAI-CI, and the image resolution and conductivity resolution experiments are carried out. The experimental results show that the resolution and the conductivity difference resolution are 0.8 mm and 0.1 S/m, respectively.