Nd∶YAG激光间质内热毁损犬和猪肝脏的实验研究

Interstitial Nd∶YAG Laser Hyperthermal Lesions in Liver:An Experimental Study

目的研究影响激光热毁损区的各种因素,包括“激光汽化兼热杀癌肿瘤理论模型”已考虑的近似简化条件、以及未考虑的复杂或可变因素,为激光手术安全操作提供参考依据。方法由理论模型计算Nd∶YAG激光功率为7W(波长1064nm)、汽化空腔直径(mm)为4.40、5.40、6.40、7.40时所需的照射时间。将Nd∶YAG激光裸光纤插入活体和离体犬肝、离体猪肝(增加8.40mm数据点)定时照射。照射后即刻沿光纤剖开标本,测量激光热毁损区域的大小,作统计学相关对比分析,建立线性回归方程。结果理论模型对汽化空腔大小的数值模拟结果在4.40～7.40mm范围内与实验数据基本符合。能用汽化空腔理论值进一步估计空腔外围瞬态凝固区域长短径的平均值。对空腔或凝固区长短径均值的Pearson积矩相关分析表明,活体与离体犬肝对比P<0.05,离体犬肝与离体猪肝对比P<0.01。汽化空腔的形状还与光纤末端侧面透光区长短、照射前初温、肝组织各向异性等有关。结论根据数学方法选择激光的功率和作用时间来实施激光间质内热毁损某一确定范围的肝肿瘤病灶是可行的。影响汽化空腔形状的复杂或可变因素有多种,临床应用中需加以注意和利用。

Objective To investigate how the various factors affect interstitial laser hyperthermal lesions in liver,including the simplex factors considered by“the theoretical models of vaporizing and heat-killing therapy of cancer with laser”and the complex or changeable factors not considered by the theoretical models.The results could be used to provide the reference data for the safety operating of laser surgery.Methods Based on the theoretical models,the irradiating times(Nd∶YAG laser wavelength1060nm,power7W)had been fixed in correspond with the sizes of vaporizing cavity which were4.40mm,5.40mm,6.40mm,7.40mm in diameters for the experiments.The experiments were performed in dog liver and liver excised from dog,and liver excised from pig(adding an datum of8.40mm)using bare fiber of Nd∶YAG laser.After interstitial irradiation,the samples had been cut open along the fiber immediately.The means of long and short diameters of lesions were measured and were statistically analyzed and compared.The linear equations had been set up.Results The predicted diameters of vaporizing cavity deduced from the theoretical models were better in accord with the experimental means of long and short diameters in the range of4.40-7.40mm.The theoretical data could further estimate the instantaneous mean of long and short diameter of coagulating area outside vaporizing cavity.Pearson correlative showed the group data of dog liver and liver excised from dog were correlative significant (P<0.05)and the group data of livers excised from dog and pig were correlative significant (P<0.01).The shape of vaporizing cavity has been in relationship with many factors,such as the side area of light-fiber tip,initial temperature before irradiation,different nature in every direction of liver.Conclusions Itˊs possible to get a defined liver cancer target of ILTT by selecting the combination of laser output power and irradiation times according to the mathematical methods.There are many factors could affect the shape of vaporizing cavity.They must be taken note and advantage of in application of laser surgery.