生物组织微结构特征的变化是医疗评估的重要依据。光声成像技术是目前最具潜力的医学影像技术之一。由于分辨率受限于接受系统所获得光声信号的最小波长，基于时域参数的光声成像很难有效地反映生物组织内部微结构特征的变化。实验研究表明光声信号的频谱特性参数能够反映组织内部的微结构特征。但是，基于频域参量光声成像的机理至今没有澄清，频域成像参量与生物组织微结构特性与功能特性的对应关系也不清楚，频谱参量光声成像系统的参数选择和优化问题也没有解决。本项目将从理论分析、计算模拟、物理模型实验和生物组织实验等多个不同方面和层次研究频域参量光声成像与组织微结构的关系，阐明频域参量光声成像的机理，构建频域参量光声成像系统，并对频域参量光声成像系统的系数进行优化。在此基础上，将频域参量光声成像系统应用于实际生物组织的成像研究，探索该光声成像系统在生物医学领域中潜在的应用。本项目不仅富有学术意义，而且具有重要的应用前景。

The change of the microstructural characteristics of biological tissue is the one of the important basis of medical evaluation. Photoacoustic imaging technology is currently the most potential medical imaging technique. However, the resolution of photoacoustic imaging based on time domain parameters is limited due to the minimum wavelength of photoacoustic signal accepted by the system, which induces the difficulty to effectively reflect the microstructural characteristics of biological tissue. Now, many experimental results show that the characteristic of the frequency spectrum for photoacoustic signal can reflect the microstructural characteristics of biological tissue, which is similar to the characteristic of the frequency spectrum for ultrasonic echo signal. So far, the mechanism of photoacoustic imaging based on frequency domain parameters is not clarified, and the relationship between the frequency domain parameters of photoacoustic signal and the microstructural characteristics and functional characteristics of the biological tissue is not clear. In addition, the coefficients of photoacoustic imaging system based on frequency domain parameters should be optimized. In this project, we will make the theory analysis, computer simulation, the physical model experiments and biological experiments to clarify the relationship between the frequency domain parameters of photoacoustic imaging and the microstructural characteristics of biological tissue. On this basis, we will construct the photoacoustic imaging system based on frequency domain parameters, and optimize the coefficients of the photoacoustic imaging system. We will further apply the photoacoustic imaging system based on frequency domain parameters in actual biological tissue imaging, and explore the potential applications of the imaging system in biomedical areas.