依据组织学特征,构建静脉及其周围组织三维模型,通过扩散近似理论模拟激光腔内辐照静脉的光分布,采用有限元法求解生物热方程,获得组织各处温度分布,并根据Arrhenius方程计算激光辐照引起的损伤。比较研究了放射状光纤与放射状二环光纤的光热响应,探讨了激光功率、回拉速度、线性静脉内能量密度、静脉直径对放射状二环光纤治疗效果的影响。结果表明:采用放射状二环光纤辐照组织,各处温度较放射状光纤低,可减少光纤与血管壁的粘附;同样的线性静脉内能量密度辐照组织,激光功率较低的治疗方案安全性较高;静脉直径越大,需更高的线性静脉内能量密度才能达到治疗效果。提出的模型有利于更好地理解激光腔内治疗的作用机理。

Based on the histological characteristics, a three-dimensional model of the vein and its surrounding tissues was constructed. The light distribution of the irradiated vein was simulated by diffusion approximation theory, the biological thermal equation was solved by finite element method to obtain the temperature distribution throughout the tissue, and the damage caused by laser irradiation was calculated according to the Arrhenius equation. The photothermal response of a radial fiber and a radial 2ring fiber was compared. The effects of laser power, pull-back speed, linear endovenous energy density and venous diameter on the therapeutic effect of the radial 2ring optical fiber were discussed. The results show that the temperature of the tissue irradiated by the radial 2ring fiber is lower than that by the radial fiber, and the adhesion between the fiber and vascular wall could be reduced. When the tissue is irradiated by the same linear endovenous energy density, it is more secure in the lower laser power treatment. The larger the vein diameter, the higher the linear endovenous energy density is required to achieve the therapeutic effect. The proposed model is helpful to better understand the action mechanism of the endovenous laser ablation.