微波热声成像和光声成像技术具有高对比度、高分辨率、无电离辐射等优点，近年来受到了广泛的关注。但通常光声成像技术的探测深度浅，微波热声成像不能较好地区分高含水量的正常组织和肿瘤组织。本项目拟开展的VHF脉冲热声成像技术利用VHF频段电磁脉冲对生物组织进行激励，并采集所激发的热声信号进行成像，该技术可弥补光声成像穿透深度不够和微波热声成像对于高含水量生物组织和肿瘤对比度不足的问题。本项目从电磁仿真和声学仿真两个物理过程对热声效应进行建模，构建多物理场一体化仿真平台；研制VHF脉冲热声成像实验平台，对高含水量、多种离子浓度的组织的热声响应进行比对分析；根据电导率模型及VHF频段的热声信号和成像之间的关系，开展基于模型的电磁-声学高效精确反演方法研究；最后，对仿体组织及真实的离体生物组织进行成像实验研究，验证VHF热声成像技术的可行性。项目的研究可为VHF脉冲热声技术的发展提供理论和实验数据支持。

Microwave thermo-acoustic imaging and photoacoustic imaging have many advantages, such as high contrast, high resolution, non-ionizing radiation, etc., which have attracted lots of attentions in recent years. However, photoacoustic imaging has the drawback of low detection depth. And microwave thermo-acoustic imaging cannot well distinguish tumors and normal biological tissues with high water content. The technique of VHF pulse induced thermo-acoustic imaging which will be studied in this project utilizes VHF band electromagnetic pulse to illuminate on biological tissue, collects stimulated thermo-acoustic signal and carries on image processing. This technique can make up the shortage of low penetration depth for photoacoustic imaging technique and the shortage of low contrast between tumors and biological tissues with high water content for thermo-acoustic imaging technique. This project will build a multi physical field integration simulation platform based on thermo-acoustic effects modeling with two physical processes, i.e., electromagnetic modeling and acoustic modeling. An experimental platform for VHF pulse thermo-acoustic imaging will be developed, based on which, thermo-acoustic effects for tissues with high water content and different ion concentrations will be compared and analyzed. Based on the conductivity model and the relationship between thermo-acoustic signal and image, model based electromagnetics-acoustics inversion algorithm will be researched, which has high accuracy and efficiency. Finally, in order to demonstrate the feasibility of the technique of VHF pulse thermo-acoustic imaging, experiments with imitating tissues and real in vitro biological tissues will be conducted. The research of this project will provide the supports in theory and experimental data for the development of the technique of VHF pulse thermo-acoustic imaging.