Whelan W M, Wyman D R
Ryerson Polytechnic University, Toronto, Ontario, Canada.
Lasers Surg Med. 1999;24(3):202-8. doi: 10.1002/(sici)1096-9101(1999)24:3<202::aid-lsm5>3.0.co;2-8.
Interstitial Laser Photocoagulation (ILP) is a minimally invasive cancer treatment technique, whereby optical energy from implanted optical fibers is used to therapeutically heat small, solid tumors. In this work, the potential of ILP without tissue charring is investigated.
STUDY DESIGN/MATERIALS AND METHODS: Optical diffusion and bio-heat transfer equations were used to develop dynamic models of interstitial laser heating in liver in vivo. Modifications in the optical properties due to tissue coagulation (T > or = 60 degrees C) were incorporated into the physical description. In addition, the effect of three different blood perfusion patterns on temperature distributions was explored. Model-predicted temperatures were used as an index for thermal damage based on an accumulated temperature injury (Arrhenius) model. Thermal damage dimensions were determined with tissue temperatures constrained to remain below 100 degrees C, so as to minimize the potential for tissue charring and smoke production.
The model predicts that increases in scattering due to coagulation and choice of perfusion pattern affect substantially thermal damage dimensions. The results indicate that, for single fiber ILP at 2.55 W for 600 s, the maximum achievable thermal damage diameter in liver, without charring, is 9.6 mm. In addition, ILP performed with high-low power ramping may have an advantage over constant power treatments, in that, larger volumes of thermal damage can be realized earlier in an irradiation.
For ILP performed with a single spherical emitting fiber, optimal irradiation parameters exist such that thermal lesions in liver up to approximately 10 mm in diameter can be induced while the maximum tissue temperature remains below 100 degrees C, avoiding tissue charring.
间质激光光凝术（ILP）是一种微创癌症治疗技术，通过植入光纤的光能来治疗性加热小型实体肿瘤。在本研究中，对无组织炭化的间质激光光凝术的潜力进行了研究。
研究设计/材料与方法：利用光扩散和生物热传递方程建立了肝脏体内间质激光加热的动态模型。将组织凝固（T≥60℃）引起的光学特性变化纳入物理描述中。此外，还探讨了三种不同血液灌注模式对温度分布的影响。基于累积温度损伤（阿累尼乌斯）模型，将模型预测的温度用作热损伤的指标。通过将组织温度限制在100℃以下来确定热损伤尺寸，以尽量减少组织炭化和烟雾产生的可能性。
模型预测，凝固引起的散射增加以及灌注模式的选择对热损伤尺寸有显著影响。结果表明，对于2.55W持续600s的单光纤间质激光光凝术，在不产生炭化的情况下，肝脏中可实现的最大热损伤直径为9.6mm。此外，高低功率斜坡式间质激光光凝术可能比恒功率治疗具有优势，因为在照射早期可以实现更大体积的热损伤。
对于使用单个球形发射光纤进行的间质激光光凝术，存在最佳照射参数，可在最大组织温度保持在100℃以下的情况下，在肝脏中诱导出直径约10mm的热损伤，避免组织炭化。
