Development of optical CT imaging system using multi-wavelength and short pulse of light

为了实现光学CT，本研究旨在开发一种先进的测量技术，利用多波长和超短脉冲的光来获取生理信息。通过本论文的研究，取得了以下成果：1)提出了抑制生物组织中强散射的原理。利用这一原理，我们可以检测到通常隐藏在强散射分量中的弱近轴散射光分量。2)将超短脉冲时间分辨测量技术应用于近轴散射光的检测。发展了一种获得入射光束沿光轴方向吸收积分的技术。3)研制了一套应用该技术的实验系统。在该系统的实验中，得到了散射介质中的吸收分布。利用这种技术，重建图像的空间分辨率有了显著的提高。…更贴切地说。此外，定量测量吸收分布成为可能，这在没有这项技术的情况下是困难的。4)针对无法检测到透射光的身体部位，提出了一种利用背向散射光进行断层成像的原理。为了利用这一原理，开发了一种测量技术。在仿真研究中，阐明了该技术的有效性和特点。5)开发了一个使用该技术的实验系统。重建了生物组织模型中的吸收分布。结果表明，重建图像与给定的分布有很好的一致性。然而，在定量测量方面还需要进一步改进。研究还发现，测量误差的影响是不可忽略的。为了克服这些问题，提出了一种新的利用多波长超短脉冲光的重建算法。在仿真和实验中，验证了该方法的有效性。较少

With a view toward the realization of an optical CT, this study was conducted to develop an advanced measurement technique to obtain physiological information using multi wavelength and ultra-short pulse of light. Through this study, the following results were obtained.1) A principle to suppress the strong scattering in biological tissue was developed. With this principle, we can detect a weak near-axis scattered component of light which is usually buried in a strong scattered component.2) A time-resolved measurement technique with an ultra-short pulse was applied to the detection of the near-axis scattered light. A technique to obtain the integral of absorption along the optical axis of the incident beam of light was developed.3) An experimental system was developed to use the above technique. In the experiment with this system, the absorption distribution in a scattering medium was obtained. With this technique, the spatial resolution of the reconstructed image was improved significa … More ntly. In addition, the quantitative measurement of absorption distribution became possible, which had been difficult without this technique.4) A principle of cross-sectional imaging using backscattered light was newly developed for the body part in which transmitted light could not be detected. To utilize this principle, a measurement technique was developed. In a simulation study, the effectiveness and the property of this technique were clarified.5) An experimental system was developed to use this technique. The absorption distribution in a model phantom of biological tissue was reconstructed. As a result, the reconstructed image agreed well qualitatively with the given distribution. However, further improvement was required for the quantitative measurement. It was also found that the effect of measurement error was not negligible. A new reconstruction algorithm was developed to overcome these problems by the use of multi-wavelength and ultra-short pulse of light. In the simulation and experiment, the effectiveness of this new technique was verified. Less