Basic study for non-invasive measurement of internal function of animal body with light

为开发可视化动物体内功能信息的测量技术进行了基础研究。通过理论和实验研究，得到了如下结果. [功能信息的跨体成像]（1）发现700-900 nm范围内的波长适合于跨体成像。(2)采用钛宝石激光器和高灵敏度CCD相机研制了跨体成像系统。它使我们能够获得小鼠腹部内脏器官的透照图像。在多波长测量中，成功地可视化了肾脏中的氧合变化。(3)在大鼠脑的透照成像中，成功地测量了由颈动脉闭塞引起的血容量变化。[散射抑制和CT成像]（4）设计了抑制透射光中散射成分的技术。该技术基于激光的空间准直和光检测中的差分原理。在使用模型体模的测量中验证了该技术的有效性。(5)上述技术被证明不适用于活体动物。其原因被认为是光在空气-物体边界处的折射和反射。新发明了一种克服这个问题的技术。(6)开发了一个实验系统，使我们能够同时利用上述两种技术。利用该系统获得了小鼠腹部的CT图像。在图像中观察到肝脏和肾脏的存在。(7)一种新的技术被开发出来，它使用散射光代替通常难以测量的微弱非散射光。在计算机模拟中，验证了使用该技术获得CT图像的可行性。

A fundamental study has been conducted for the development of the measurement technique to visualize the functional information in an animal body. Through theoretical and experimental studies, the following results were obtained.[ Trans-body imaging of functional information ](1) It was found that the wavelength in the range of 700-900 nm is appropriate for the trans-body imaging.(2) Trans-body imaging system was developed with Ti-Sapphire laser and high sensitivity CCD camera. It enables us to get the transillumination image of the internal organ in a mouse abdomen. In the multi-wavelength measurement, the oxygenation change in a kidney was visualized successfully.(3) In the transillumination imaging of a rat brain, the change in blood volume caused by the occlusion of a carotid artery was measured successfully.[ Scattering suppression and CT imaging ](4) A technique to suppress the scattered component in transmitted light has been devised. This technique is based on a spatial collimation of laser light and a differential principle in light detection. The effectiveness of this technique was verified in the measurement using a model phantom.(5) The above technique turned out to be inapplicable to a living animal body. The cause was found to be the refraction and reflection of light at an air-body boundary. A technique to overcome this problem was newly devised.(6) An experimental system was developed which enables us to utilize above two techniques simultaneously. Using this system, the CT images of a mouse abdomen were obtained. The existence of a liver and kidneys were observed in the images.(7) A new technique was developed which uses scattered light instead of the weak nonscattered light which is usually difficult to measure. In a computer simulation, the feasibility to obtain a CT image using this technique was verified.