| In this paper the new technology in Biomedical Photonics-----diffusion photondensity wave(DPDW) was studied in theory and simulation. The circumstance when anabnormal object was contained in tissue was also discussed.On the basics of DPDW's theory, we have made theoretical improvement on thephysical model that has been had. Second-order analytical solutions of diffusionequation of DPDW are presented, which were solved in three kinds ofboundaries----infinite, half-infinite and finite cube. And the relationship between theabsorption coefficient and the flux is derived, for the flux can be easily obtained inpractical experimentsThe analysis solution of diffusion equation is too complex to carry out thesimulation directly, it isn't adapted to experiment and engineering application. So theanalysis solutions in three boundaries were predigested by using matrix transformmethod. And the simulation velocity was improved much. Using this relationship andthe optical properties of typical forearm tissue, the second-order computation results aregiven in simulation. Compared with the results of first-order solution, second-ordersolution is more accurate and the precision in calculation is greatly improved.Using the presented typical optical parameter of human being's forearm tissue, thesimulation result of the analysis resolution was shown. The site of abnormal object canbe judged from the lowest site of photon density. Just when detector and the abnormalobject are in the same line, photon density is the lowest. These results validate thetheory have been provided, and we found that the basic optical parameters can be gotfrom the analysis to the intensity and wave shape of photon density. We also found thatthe analysis resolution is not applicable for the conditions that diffusion coefficient islarge.The research consequences may offer a theoretical and experimental reference toknow the property of DPDW transmitting through Bio-Tissue and Bio-Tissue imagingand clinical diagnose and therapy. |
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