电极间距与电极直径对恒功率下双极射频熔脂效果影响的研究

在双极射频应用于局部脂肪堆积的无创治疗的过程中,关于双极射频设备的部分设计参数目前还没有形成统一的规范。采用有限元方法和离体实验,分析双极射频熔脂时不同参数对组织熔脂效果的影响,寻求在双极射频尽量不会对皮肤层造成热损伤的同时,实现较大范围熔脂效果的熔脂参数配置。采用COMSOLMultiphysics进行生物组织热电耦合的有限元分析;为验证模型有效性,采用一种自研的单路双极射频输出设备,对离体猪腹部组织进行实验。有限元分析结果显示:经双极射频加热30min后,在功率为10W,电极球直径分别为3、5、8mm,电极间距分别为2和3cm的熔脂参数配置下,皮肤层的最终温度低于热损伤阈值温度,且部分脂肪层在热损伤区域内;域点探针所显示的脂肪层热损伤区域内的温度变化曲线满足熔脂温度要求。不同熔脂参数配置,对双极射频加热下组织内的温度分布具有显著影响。在10W功率下,采用直径为8mm的球型电极,电极按压皮肤的深度为1mm,在电极间距分别为2和3cm的条件下,脂肪层内产生最大面积的连续热损伤区域和点状热损伤区域,热损伤区域的面积分别为2.84和2.55cm²。相同熔脂参数配置的离体实验表明,与组织模型相同位置处的热电偶探针的最终温度和对应的域点探针相差0.92℃±0.43℃。有限元分析结果和实验结果基本一致。由仿真结果和实验结果可知,上述熔脂参数配置可使双极射频不会对皮肤层造成热损伤,同时在脂肪层内产生有效的热损伤区域,并且热损伤区域内的温度达到了熔脂要求。合理的熔脂参数配置是决定双极射频熔脂是否成功的一项关键因素。

Study on the Effect of Electrode Spacing and Electrode Diameter on Bipolar Radiofrequency Fat Melting at Constant Power

So far there is no uniform specification for some design parameters of bipolar radiofrequency (RF) devices for noninvasive treatment of local fat accumulation. In this work,the finite element method and external experiment were used to analyze the influence of different parameters on the fat melting effect of tissues in bipolar RF,seeking for the fat melting configuration with a large range of fat melting effect without causing thermal damage to skin layer as far as possible. The finite element analysis of thermoelectric coupling of biological tissues was carried out by COMSOL Multiphysics. To verify the validity of the model,a self-developed single-channel bipolar RF output device was used to perform RF output of pig abdominal tissues. The results of finite element analysis showed that the final temperature of the skin layer was lower than the thermal damage threshold temperature and part of the fat layer was in the thermal damage area under the fat melting configuration with the power of 10 W,the diameter of the electrode sphere of 3,5,8 mm and electrode spacing of 2 and 3 cm after 30 min heating with bipolar RF;the domain point probe showed that the temperature curve in the thermal damage area of the fat layer met the requirement of the fat melting temperature. The temperature distribution in tissues under bipolar RF heating was significantly affected by different fat melting configurations. At a power of 10 W,when using a spherical electrode with a diameter of 8 mm and pressing the skin to a depth of 1 mm,under the condition of electrode spacing of 2 and 3 cm,the largest area of continuous thermal damage area and spot-shaped thermal damage area within the fat layer will be generated,and the area of thermal damage area is 2.84 and 2.55 cm²,respectively.External experiments with the same fat melting configuration showed that the final temperature of the thermocouple probe at the same position as the tissue model was 0.92±0.43℃ different from that of the corresponding domain point probe. The finite element analysis results were consistent with the experimental results. According to the results of simulation and experimental validation,the above configuration made the bipolar RF not cause thermal damage to the skin layer,at the same time while generate effective thermal damage area in the fat layer. The temperature in the thermal damage area could meet the requirement of the fat melting temperature. The reasonableconfiguration is a critical factor for the success of bipolar RF fat melting.