Light And Temperature Distribution By Laser Ablation Under1064nm

Laser ablation of tumor is generated through thermal effects betweenorganizations by laser irradiation. The transmission and distribution oflaser in biological tissues and the interaction effect between laser andtissues are the photoluminescence theoretical basis of the thermaleffects.Laser distribution in tissues is an important prerequisite for specialtissue of choosing laser treatment parameters, and it also has significantimportance to analyze the photothermolysis response characteristics ofbiological tissues from clinical perspective.The1064nm laser can cure thebiological tissues that contain more moisture better because of the selectivephotothermolysis between biological tissue and laser. The interactionbetween the1064nm laser and biological tissue is studied in this article.At present, for simulating the optical transmission problems inbiological tissue, the light volatility character was ignored. From lightparticles, photon transmission theory was studied. There are lots ofresearch on the photo transmission theoretical model, but some of themhave their limitations. As Monte Carlo is the only randomized algorithms that is applicable for a variety of complex biological tissue andmulti-layered organizational structure, the method is used widely. Finiteelement method (FEM) and finite difference method(FDM) is the mostcommon numerical analysis method to solve biological tissue heatconduction equation. The biological tissue thermal parameters changingalong with temperature is most overlooked at the present research thatrelated to biological tissue photothermolysis effect of laser irradiation. Infact, biological tissue thermal parameters change with the temperature.Based on the description of the basis of biological tissue structure, thispaper firstly introduce laser transmission theory in the biological tissuefollowed by the interaction between laser and biological tissue. Beamdiffusion and Monte Carlo method are analyzed to describe transmissionand distribution of laser respectively. Apart from that, the transmission offinite-diameter Gaussian laser in the internal biological tissues is giventhough convolution calculation based on the analysis of the infinite thinbeam distribution though Monte Carlo method. The result show that thescattering characteristics of light were relatively obvious by using MonteCarlo calculation method, and energy distribution of light is moredispersed than beam diffusion method.Secondly, on the basis of the optical transmission problem, this paper analyzes the biological tissue heat conduction mechanism and give the heattransfer equation solution conditions that include thermal parameters of theorganization, boundary conditions and initial conditions. Light distributionresults including beam diffusion method and Monte Carlo method, areused as heat source in bioheat equation. And the calculation model isdivided reasonably to two dimension in the cylinder coordinate of axialsymmetry. Heat transfer model on tissue surface of cattle liver irradiatedby laser is established. Matlab and Ansys finite element software is utilizedto solve the nonlinear partial differential equation of biological heattransfer though finite element methods. And this paper also discusses thetemperature distribution of biological tissues for laser of low powerirradiating for a long time. This paper establishes the dynamic thermalparameters model about biological tissue. The response of biological tissueto dynamic thermal parameters is analyzed compared with the constantthermal parameters conditions.In addition, this paper develops visualization software of numericalanalysis for tissue temperature distribution, simplifying the tedioussimulation process...