Fundamental Study for the Non-Invasive Laser Coagulation Method

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A serial research from the fundamental to application has been conducted for developing novel method of non-invasive laser coagulation method. In the first experiment, absorption and transparency of laser in tissues and also thermal properties such as heat conductivity and diffusivity are measured for understanding and modeling the laser coagulation. The measurement was made for meats and tissues of the pig as the test material. To confirm the possibility of the present idea of coagulation, theoretical analysis of the temperature distribution in tissues when the laser irradiates and the surface of tissues is cooled by cold water. After the theoretical analysis, experiment of laser irradiation by employing meats as the test material was carried out and compared with the analytical results. In the experiments, water temperature, water flow rate, laser strength and laser irradiation time were changed to investigate the effects for the tissue coagulation. The theoretical and experimental results agree well each other. At the next stage, a prototype handy coagulation devise was designed and produced for the experiment of application. It is found that this device can apply well to the coagulation of meats. So we proceeded to the animal tests. Namely, at the last stage of the research, animal tests were conducted with an aim to apply the present method to the coagulation of stomach of the pig. The changes of the before and after laser irradiation were investigated in detail, and the size of the region of coagulated tissues was measured and the relation of the size to the experimental parameters such as laser power and irradiation time was made clear. With an aim to accumulate sufficient data and confirm the applicability of the present method, the animal tests are still conducting.