激光医学的内容包括用激光新技术去研究、诊断、预防和治疗疾病。激光溶栓是用激光爆破、分解和破裂的方法将血管中的血栓消融，达到溶栓的目的，是治疗血栓病的潜在的有效方法。激光诱导间质热疗（LITT）是将激光导入人体通过热效应杀死肿瘤的一种新型手术方法，具有微创、快捷、痛苦小和止血等优点。激光溶栓与激光诱导间质热疗都基于激光与生物组织的热相互作用机理，是激光医学的重要组成部分。本文将非傅立叶传热理论应用于脉冲激光与生物组织相互作用的研究，解出了球形热源作用下组织中的温度分布。并根据Arrhenius损伤的速率理论，分析了损伤阈值温度与激光脉宽的关系。指出了为了避免激光溶栓中热损伤的激光参数的优化原则。针对现有溶栓激光光源的不足，提出可主动控制的被动调Q激光器。首先实现了以Cr4+:YAG为可饱和吸收体的可主动控制的被动调Q Nd:YVO4 激光器。将该脉冲激光进行放大和倍频，进而实现了可主动控制的被动调Q绿光激光器。进行了绿激光溶栓实验，证实了理论分析结果的正确性。建立了包含大血管的LITT模型，对于激光和热量在生物组织中的传输进行了数值模拟。采用Monte Carlo模拟方法计算组织内激光能量的分布时，考虑了肿瘤组织和正常组织光学性质的差异，以及激光能量在两层组织界面处的反射。然后将Pennes生物传热方程和血流换热能量方程相结合，求解出含有血管局部冷却效应的组织温度场。最后由Arrhenius方程得到组织损伤度随时间的变化。定量比较了无血管及三种不同血管直径的情况下，血流局部冷却效应对LITT疗效的影响。建立了含大血管的LITT实验系统，利用红外测温仪进行了包含大血管的体模、离体组织及活体组织激光肿瘤热疗模拟实验，第一次从实验角度考察证明了大血管对于LITT治疗的影响，并做了详细的分析和讨论。实验结果对LITT研究有指导意义。根据激光溶栓研究与生物传感器研究的需要，首次设计制作了Tm3+/Yb3+共掺杂的TiBa玻璃微球谐振腔。利用此微球腔实现了从633nm到478nm的光上转换，并观察到了型貌共振现象，实验结果与理论结果相符。
Laser medicine is an interdisciplinary field that grew out of the integration of medical science and laser technology. It applies new laser technologies to research, diagnosis, prevent and treat diseases. Laser thrombolysis, which falls into the same category of laser surgery with laser thrombolysis, is an interventional procedure that removes clots in the vessels through the formation and collapse of the bubbles by the laser heating. It is a potential mean for clearing blood clots in occluded vessels. Laser-induced Interstitial Thermotherapy（LITT） is a new type of tumor therapy method, which has the advantages of minimal invasive, quick, relatively painless and good homeostasis. Laser throbolysis and LITT, both based on the thermal interaction of laser and tissue, are the important component parts of laser medicine.Non-Fourier heat transfer theory was applied to the study of interactions of pulsed laser and tissues in this dissertation. The temperature distribution stimulated by a spherical heat source was worked out analytically. Meanwhile, the relation of tissue thermal damage threshold and laser pulse width was derived from Arrhenius rate process equation. The optimization method was pointed out to prevent laser damage during laser thrombolysis. To meet the needs of laser thrombolysis, this dissertation presented a novel kind of laser named controllable passively Q-switched laser (CPQL). Nd:YVO4 CPQL with Cr4+:YAG as saturable absorber was analyzed and demonstrated for first time. Then the laser was amplified and frequency-doubled into green laser. After that, the experiments of laser thrombolysis were performed with the green laser. The theoretical analysis was validated by the experiments results.The principles of photon transportation and heat transfer in biological tissues including large vessels were simulated based on the physical and mathematical models for LITT, in which the difference of optical characteristics of tissue and tumor was involved, as well as the light reflection at the border of tumor. The laser energy distribution was simulated by the Monte Carlo method. The Pennes bio-heat equation and the energy equation for the blood vessel were utilized to numerically calculate the temperature distribution. The corresponding thermal damage distribution was determined by the Arrhenius rate process formulation. The situations with three different sizes of blood vessels were simulated to compare their cooling effects during LITT.A LITT experimental system with large blood vessel was set up, in which an infrared thermometer was introduced to map the surface temperature of the sample, aiming to clearly grasp the contribution of large blood vessels on the heat transfer in living tissues during a LITT. Moreover, an in vivo test on the laser heating effects on the temperature responses was also made at several selected sites of human hand either with or without large veins underneath the skin. According to the necessities of the researches on laser thrombolysis and biosensors, a TiBa glass microsphere oscillator co-doped with Tm3+/Yb3+ was designed and fabricated. The optical up-conversion was measured and discussed and the morphology-dependent resonance of the up-conversion light was observed. The experimental result was found to be in line with the theoretical analysis. Fast temperature sensor and high sensitivity biosensor based on the microsphere oscillator could be achieved through further study.
