本文利用模擬真實情況的數值模型，研究脈衝雷射照射活 體組織的影響。文章初始比對現有文獻的實驗資料，驗證 本模型的精確度，所得結果發現在燒灼及熱凝結的預測深 度上，在低入射雷射能量，與實際實驗值相當吻合，而在 高入射雷射能量的分析上發現，在能量超過30 J/cm2時， 實驗和模擬間的誤差值會隨著能量的增大而變大。之後進 一步研究在組織燒蝕的臨床治療中脈衝時間，入射能量和 脈衝頻率等參數，發現入射能量和燒灼的深度成正比，而 脈衝頻率會因能量集中的效果，對燒灼深度會有影響，但 幅度變化並不大，在脈衝時間的研究指出，此參數的變化 並不會產生明顯的效果。 在分析低能量雷射對皮膚組織溫升的效應方面，模型中利 用將皮膚組織分層設定的方式，觀察出皮膚表面和真皮層 的溫差相當高，臨床治療需要有效的控制脈衝的時間。在 光動力治療方面，分析內部能量的分佈對治療效果的影響，發現在各項的參數中，提高腫瘤的吸收係數可有效的 增加療效，且當腫瘤的深度增加時，治療的的困難度會大 幅的提升。同時發現組織的等效衰減係數對腫瘤吸收能量 大小的影響最大，故在臨床上的改善應以此方面為主。由 上述的研究提供於臨床應用，具有增加效能並降低可能產 生之副作用的貢獻。 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.
