摘要
目的 探讨植入式微波在仿肝组织体模中热场的分布规律。方法 在体模实验中每次精确布 16个点 ,每点重复 5～ 9次 ,测量温度的分布 ,并求解组织的比吸收率 (specialabsorptionrate ,SAR)。在Pennes生物热方程的基础上 ,推导建立肝癌植入式微波热疗的热作用数学模型 ,借助有限元法对三种加热功率、作用时间 ( 6 0W 5min、5 0W 10min、40W 30min)下温度分布进行广泛的模拟计算和预测。结果 通过体模实验确定了SAR分布。在r方向呈指数衰减 ,θ方向为余弦拟合 ,z方向呈三次多项式拟合 ,且前向温升大于后向。三种功率下SAR分布不同 ,并且SAR与功率分布之间没有线性关系。在SAR基础上 ,计算机动态模拟重建微波热场。结论 肝体模实验证明微波热场的分布呈以天线为中心向外有规律的依次递减 ,该规律可通过计算机模拟重建 ,模拟重建的热场具有三维动态连续监测的特点。这为临床微波治疗肝癌中有效调控热场的温度奠定了理论和技术基础。
Objective To investigate thermal distribution of implanted microwave coagulation in equivalent liver phantom.Methods In equivalent phantom test of the liver, it was available to pinpoint the spots of measurement and measure the temperature precisely. Such measurements were performed in 16 sites each time and at each site were repeated 5～9 times at the same power output level. Sixteen thermocouples were used to measure the transient temperature from which the specific absorption rate (SAR) values were determined. Based on Pennes formulation of thermal biology, the thermal model of implanted microwave hyperthmia for liver cancer was deduced. Thermal distributions were widely calculated and predicted by computer simulation with finite element model (FEM) under three power output (60 W 5 min, 50 W 10 min, and 40 W 30 min).Results The SAR distributions were determined in the liver equivalent phantom test. In the r direction, microwave thermal field was fitted with an exponential decay. In θ direction, it was fitted with cosine θ. In the z direction, it corresponded to a third order polynomial. Speed of temperature rise in z >0 direction was faster than that in z <0 direction. SAR distribution was different at different power output. There was no relationship between SAR values and power outputs. Based on SAR values, thermal fields were dynamically reconstructed with computer simulation.Conclusions Temperature distributions of microwave radiation are regular, which decay from central electrode to peripheral tissue. The temperature distribution can be reconstructed with computer simulation. Computer simulation can dynamically monitor the temperature rise on three dimensions. It provides a theoretical and technical basis for precisely controlling thermal fields during the microwave hyperthermia treatment of the liver cancer.
出处
《中华超声影像学杂志》
CSCD
2002年第4期236-239,共4页
Chinese Journal of Ultrasonography
基金
国家自然科学基金项目 (39870 794)
关键词
超声检查
微波
治疗应用
计算机模拟
温度场
肝癌
Ultrasonography
Microwaves/therapeutic use
Computer simulation
Temperature field
