Laser Interaction With The Gastric Tissue Of Monte Carlo Simulation Study

Laser technology has been used for clinical diagnosis and treatment in recent years as a new means.As the basic research,we are interested in the mechanisms on the interaction of light and the tissues and the transmission properties.In this dissertation,the transmission properties of the laser in gastric tissue were studied with the Monte Carlo method.It gave the certain theoretical basis for the clinical diagnosis and treatment using the laser technology.Main contents of the dissertation included:The studies were demonstrated under the infinite incident beam that:1) The diffuse reflection increases with g decreasing,the transmittance increases with g increasing;2) The diffuse reflection and transmission at 632nm exciting wavelength are significantly higher than the ones at 337 nm and 405 nm exciting wavelength;3) The diffuse reflection and transmission of the normal gastric tissue are higher than the ones of the abnormal gastric tissue at 405nm exciting wavelength.The diffuse reflection and transmission of the normal gastric tissue and the abnormal gastric tissue ate nearly equally;4) The diffuse reflection is invariable within 0°～60°,and the one is decreasing beyond 60°;5)The fluence rate is decreasing exponent at 337nm and 405nm exciting wavelength.The fluence rate is basic invariable at 632nm exciting wavelength when the thickness of the gastric tissue is 0.1cm.The studies were demonstrated under the finite incident beam that:1) The diffuse reflection and transmission of the gastric tissue by Gaussian beam are similar to Gaussian distribution,The diffuse reflection and transmission of the gastric tissue by flat beam have a small platform when r is small.The diffuse reflection and transmission increase as r decreasing;2)The peak value of the fluence rate by the Gaussian beam is higher than the one by the flat beam,and the peak by the Gaussian beam is sharper;3) The penetration depth by Gaussian beam in the abnormal and normal tissue is less than the one by flat beam in the tissue in the abnormal tissue and normal tissue.When the normal and abnormal tissue were irradiated at 632 nm wavelength Gaussian beam,the penetration depth by Gaussian beam is less than the one by flat beam in the tissue,and the penetration depth in the normal tissue is less than the one in the abnormal tissue.