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     * Monte Carlo Simulations to Measure Light Dosimetry in Biological Tissue
In a PDT treatment, accurate light dosimetry is specially important as it is to be expected that applying too little light or too much light could result in inadequate tumor cell kill. The basic theory of this method is statistical iteration of simulation at phantom medium and can model any complex condition in biological tissues without any kind of tool. We performed Monte Carlo simulation with phantom layer having the optical properties of biological tissues. In this result, we could obtained the acceptable light dosimetry in biological phantom. Monte Carlo simulation is very powerful approaching model in radiation transfer for solving a variety of physical and mathematical problems.
* Measurement of the Oxygen of Biological Tissue using Optical Methode
* Signal Processing Method in Frequency Domain for Measuring Oxygen Saturation in Biological Tissue
For measurement of the oxygen saturation and blood volume in biological tissue it is very important to get information about diagnosis of peripheral vascular disease in lower extremity. In order to assessment the tissue microcirculation status, we used noninvasive optical techniques to considerably enhance the small changes in the light scattering by the changes of oxygenation level of tissue. We presented the measuring device and experimental results in human tissue.

* Measurements of Optical Coefficients of Biological Tissue

We measured the absorption coefficient of the biological tissues and compared with each other to use them to develop medical applications using light. The optical coefficient is representative of the characteristics of the materials. So, we can characterize the biological tissue with the optical coefficients. Because the optical coefficient is concerned with the conformation and biochemical component of the biological tissue, we experimented as the wavelength between 500 nm - 900 nm on the normal and tumor samples of the animal and human. For the mouse, there are differences of the absorption coefficients between normal tissues and tumor. The absorption coefficient of the normal tissue has similar values as the wavelength. But, the absorption coefficient of the tumor is changed as the wavelength. In the nuclei of the tumor, the DNA increase rapidly. So there are differences of the absorption coefficient of the tumor at each wavelength. The absorption coefficients we measured can be a useful implement to demonstrate indirectly the biochemical component and internal structure of the biological tissues.