中文摘要：

为防止激光诱导间质内热疗治疗肿瘤时激光光纤加热段周围组织的炭化，本文提出了一种采用深低温流体对激光光纤及其临近组织进行降温冷却的方法。为验证该方法的可行性，本文对采用该方法后激光间质内热疗过程中组织的传热问题进行了深入的数值研究。结果表明，深低温流体冷却方法可避免局部高温对组织的炭化，并显著扩展有效加热范围，从而对肿瘤实旋高效的热凝固。

英文摘要：

To avoid carbonization of tissues surrounding to the heating part of laser fiber during treating tumor by laser-induced interstitial thermotherapy （LITT）, a new method using ultra-low temperature fluid was proposed for cooling laser fiber and tissues in the vicinity of laser fiber in this study. To test its feasibility, the corresponding bioheat transfer process applying this cooling method during LITT was studied through extensive numerical simulations. The results indicate that the cooling method by ultra-low temperature fluid can prevent carbonization of tissues resulted by local high temperature, significantly enlarge the effective heating area and thus actualize highly efficient thermal coagulation to tumor tissues.