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Basic studies on optical imaging of biological tissue using ultrasound-modulated near-infrared light

利用超声调制近红外光进行生物组织光学成像的基础研究

基本信息

批准号：
10480238
负责人：
YAMAMOTO Katsuyuki
金额：
$ 2.24万
依托单位：
HOKKAIDO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-10480238/
关键词：
Ultrasound Modulation of light Optical imaging Spatial resolution Detection of weak light Transmitted light Pulsed light Pulsed ultrasound 後方散乱光ドプラ効果屈折干渉計

项目摘要

In this study, a new technique to improve a spatial resolution of optical imaging of biological tissues using ultrasound-modulated light was developed, and the following results were obtained.Study on mechanisms of light modulation by ultrasoundTwo high-sensitivity detection systems of ultrasound-modulated light using a photomultiplier or an interferometer were developed. Relationships between a signal intensity of ultrasound-modulated light and a scattering coefficient of a turbid medium were obtained from experiments on a tissue phantom. Based on these relationships, the mechanisms of light modulation by ultrasound and the attenuation of modulated component due to scattering were systematically studied.Feasibility of utilizing back-scattered lightIn optical imaging using transmitted light, a source and a detector must be separately placed on a line, and thickness of an object is restricted by great attenuation of light. Therefore, the feasibility of utilizing back-scattered light was studied using the optical interferometry system that can detect a phase shift of light caused by vibration of scatterers. It was found that an ultrasound-modulated signal can be extracted from back-scattered light by employing the optical interferometry.Highly sensitive detection of ultrasound-modulated light using a 2-D optical sensorThe interferometry system was further improved so as to collect scattered light and extract a modulated signal from a speckle pattern observed by a 2-D optical sensor. A pulsed laser beam synchronized with ultrasound enabled to use a conventional CCD camera. An attenuation rate of the modulated signal with increase in a scattering coefficient was ten times less than that of the conventional method that detected near-axis transmitted light. It was concluded that this is a promising technique to realize optical imaging of biological tissues with a high spatial resolution.

本研究开发了利用超声波调制光提高生物组织光学成像的空间分辨率的新技术，并取得了以下成果。超声波调制光的机理研究开发了利用光电倍增管和干涉仪的超声波调制光的两种高灵敏度检测系统。根据对组织模型的实验，获得了超声调制光的信号强度与混浊介质的散射系数之间的关系。在此基础上，系统地研究了超声对光的调制机理和散射对调制分量的衰减。利用后向散射光的可行性在透射光光学成像中，光源和探测器必须分开放置在一条线上，而且由于光的衰减很大，物体的厚度受到限制。因此，使用可以检测由散射体的振动引起的光的相移的光学干涉测量系统来研究利用后向散射光的可行性。利用光学干涉技术可以从背向散射光中提取出超声调制信号。利用二维光学传感器实现超声调制光的高灵敏度检测进一步改进了干涉系统，使其能够收集散射光，并从二维光学传感器观察到的散斑图中提取出调制信号。与超声同步的脉冲激光束能够使用传统的CCD相机。随着散射系数的增加，调制信号的衰减率比检测近轴透射光的传统方法的衰减率小十倍。结果表明，这是一种很有前途的技术，以实现具有高空间分辨率的生物组织的光学成像。