| Summary: | 碩士 === 國立中央大學 === 機械工程研究所 === 91 ===
The physical processes of laser-tissue interactions are investigated theoretically. The radiative transfer equation (RTE) is used to
simulate the laser propagation in tissues. The model includes emission, absorption and
anisotropic scattering mechanisms. The RTE is
solved by using the discrete — ordinates method.
The energy equation is solved by the control volume based finite different method. The resulting numerical code, written in Fortran, is
validated by comparing the results with available
experimental measurements.
The effects of several important parameters on
the coagulation and ablation depths of tissue are
studied. Results show that the ablation depth
increases with the incidence fluence. The pulse
frequency of the laser has small influence on the
ablation depth. On the other hand, the ablation
depth is not affected by t he pulse duration.
Laser energy lasers are also used in thermal
treatment of skins. In this work, skins are
separated into four layers, namely, stratum
corneum, epidermis, dermis, and subcutaneous
tissue. The results show that, under laser
irradiation, the temperature difference between
the skin surface and the dermis layer is very
large. For better control of affected area,
appropriate pulse duration should be used.
For applications in photodynamic therapy (PDT), the energy distribution in tissue during the
treatment period is investigated. Increasing the
absorption coefficient of the tumor leads to
higher energy density in the tumor region, this
is beneficial fort PDT. The effective attenuation coefficient of the surrounding tissue has
profound in influence on the treatment results.
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