摘要
利用声光信号测量了组织的散射系数,理论上分析了组织散射系数与声光信号峰峰值和相对强度的定量关系,并通过有限元仿真进行了验证。搭建了声光成像实验系统,分别采用固定入射强度和改变入射强度两种方法获得了声光信号的峰峰值和相对强度,对组织模拟液的散射系数进行了测量。实验结果显示这两种测量方法的精度相当:在相同条件下,利用声光信号峰峰值测量的散射系数最大相对误差为3.34%,平均相对误差为1.35%;利用声光信号相对强度测量的散射系数最大相对误差为3.88%,平均相对误差为1.32%。在实际操作中,前者测量速度更快,而后者测量的散射系数范围更大。
Objective The optical parameters of biological tissues can reflect their physiological state to a certain extent and provide an important reference basis for clinical diagnosis. Therefore, it is of great significance to measure the optical parameters of biological tissues. The commonly used methods for measuring the optical parameters of biological tissues have problems. Diffusion optical tomography has a deep imaging depth, but it relies on the depth learning algorithm of the simulated dataset, and its accuracy in practical applications is debatable. Optical coherence tomography, which has a high measurement accuracy, is only applicable to the measurement of optical parameters of shallow tissues. The direct measurement of scattering coefficients using a transmission model leads to a large error, and it cannot meet the requirements for measurement accuracy. Acoustooptictomography (AOT) effectively combines the advantages of optical and acoustic technologies, and is expected to realize highprecisionquantitative measurement of scattering coefficients of thick tissues. In this study, the feasibility of using acoustoopticsignals to measure the scattering coefficients of tissues is confirmed by theory, finite element simulation, and experiment, and the advantages and disadvantages of the two types of measurement methods based on acoustoopticsignals are compared.Methods Combining the diffuse theory of light propagation in biological tissues with the intensity modulation mechanism of acoustoopticinteraction, the relationship between acoustoopticsignals and the scattering coefficient is obtained. The finite element software COMSOL Multiphysics is used to simulate the acoustoopticprocess in the tissue to verify the correctness of the theoretical analysis results. In the AOT experiment, the peaktopeakvalue and relative intensity of the acoustoopticsignals are obtained by fixing the incident intensity and changing the incident intensity, respectively. Combining the relationship between acoustoopticsignals and the scattering coefficient, the quantitative measurement of the scattering coefficient of the simulated tissue fluid is realized.Results and Discussions In the COMSOL Multiphysics simulation and AOT experiment, the peaktopeakvalue of the acoustoopticsignal shows a linear increasing relationship with the incident intensity (Fig. 5 and Fig. 10), and reveals an exponential decay trend with the scattering coefficient [Fig. 6(b) and Fig. 11(b)]. The relative intensity of the acoustoopticsignal does not change with the change of the incident intensity (Fig. 5 and Fig. 10), and shows the same exponential decay relationship with the scattering coefficient [Fig. 6(a) and Fig. 11(a)]. The scattering coefficient of the medium is measured by the peaktopeakvalue and relative intensity of the acoustoopticsignal obtained by the simulation. The relative errors of the scattering coefficients obtained by both methods are within 0.5% (Fig. 7). The measurement accuracy of the former method is slightly better than that of the latter in the COMSOL Multiphysics simulation. In the AOT experiments, the maximum absolute error obtained using the relative intensity measurement method is 0.26 cm-1, the average absolute error is 0.10 cm-1, the maximum relative error is 3.88%, and the average relative error is 1.32% [Fig. 12(a)]. The maximum absolute error obtained using the peaktopeakmeasurement method is 0.31 cm-1, the average absolute error is 0.12 cm-1, the maximum relative error is 3.34%, and the average relative error is 1.35% [Fig. 12(b)]. Under the same conditions, the measurement range of medium scattering coefficients using the relative intensities of acoustoopticsignals is larger than that using the peaktopeakvalues of acoustoopticsignals [Fig. 13(a)].Conclusions In this study, the quantitative relationships between the peaktopeakvalue and relative intensity of acoustoopticsignals and the scattering coefficient of tissues are obtained. The peaktopeakvalues of the acoustoopticsignals show a linear incremental relationship with the incident intensity, but the relative intensity remains unchanged with the change in incident intensity. The relative intensity and peaktopeakvalues of the acoustoopticsignals show the same exponential decay trend with the increment of the scattering coefficient. The theoretical conclusions are verified through a COMSOL Multiphysics simulation and experiment. In the COMSOL Multiphysics simulation, the relative errors of the scattering coefficients based on the peaktopeakvalues and relative intensities of the acoustoopticsignals are both within 0.5%. In the AOT experiment, the maximum relative error of the scattering coefficient measured using the relative intensity of the acoustoopticsignal is 3.88%, and the average relative error is 1.32%. The maximum relative error of the scattering coefficient measured using the peaktopeakvalue of the acoustoopticsignal is 3.34%, and the average relative error is 1.35%. It can be observed that the measurement accuracies of the two methods are comparable. In practice, the peaktopeakvalue measurement method is fast, but the relative intensity measurement method can measure a larger range of the scattering coefficient. The above conclusions initially indicate the feasibility of highprecisionquantitative measurement of scattering coefficients of biological tissues using acoustoopticsignals. This is expected to provide a novel and noninvasivetechnical means for detecting biochemical attributes such as blood glucose, triglyceride, and total cholesterol concentrations in human blood tissues and can provide a certain reference for the clinical diagnosis of related diseases.
作者
张畅
覃诗译
刘遥
孔繁玉
朱莉莉
Zhang Chang;Qin Shiyi;Liu Yao;Kong Fanyu;Zhu Lili(Key Laboratory of OptoElectronic Science and Technology for Medicine of Ministry of Education,College of Photonic and Electronic Engineering,Fujian Normal University,Fuzhou 350117,Fujian,China;Fujian Provincial Key Laboratory of Photonics Technology,College of Photonic and Electronic Engineering,Fujian Normal University,Fuzhou 350117,Fujian,China)
出处
《中国激光》
北大核心
2025年第3期33-44,共12页
Chinese Journal of Lasers
基金
国家自然科学基金青年科学基金(11804051)
福建省自然科学基金(2022J01171,2017J01742)。
关键词
生物光学
声光信号
散射系数
超声调制
biooptics
acoustooptic signal
scattering coefficient
ultrasound modulation
作者简介
通信作者:朱莉莉,llzhu@fjnu.edu.cn。
