Experimental and numerical study of microwave ablation on ex-vivo porcine lung

Microwave ablation is used to treat lung tumors by releasing microwave magnetic field to produce high temperature of more than 60 ℃ in the tumor tissues, thus causing tissue coagulation, dehydration and necrosis to achieve the purpose of treatment. However, the lack of appropriate power and time parameters for microwave ablation in clinical treatment of lung tumors leads to poor ablation or excessive ablation. In this paper, a two-dimensional simulation model of microwave antenna and ideal lung was established to realize the simulation of microwave ablation process. Meanwhile, microwave ablation experiments were carried out in ex-vivo porcine lung under different power and time. The temperature distribution was obtained by thermocouples and compared with the simulation calculation. Set 60℃ as boundary of the ablation area and the ablation time was 360 s. The length of the ablation area parallel to the antenna direction is longitudinal, and the length perpendicular to the antenna direction is transverse. From the simulation results, with the increase of ablation power (20 W to 60 W), the transverse diameter of ablation area increased from 32.5 mm to 55.6 mm, and the longitudinal diameter increased from 47.8 mm to 69.1 mm. From the results of ex-vivo experiments, with the increase of ablation power (30 W to 50 W), the transverse diameter of ablation area increased from 29.5 mm to 48.9 mm, the longitudinal diameter increased from 41.1 mm to 66.3 mm, and the maximum slot temperature increased from 75.6 ℃ to 106.7 ℃. The results of numerical simulation are slightly larger than those of ex-vivo experiments under the same parameters. When the average diameter of lung tumors is less than 40 mm, 30 W and 40 W ablation power can be selected. The ablation time is limited to 360 s. 50 W ablation power can be used to ablate the lesion quickly in a shorter time to achieve the same purpose. Although there are differences between ex-vivo and in vivo, the validity of the lung model and the influence of ablation parameters in the simulation are verified in this paper. The ablation area under different parameters was obtained, which served as a reference data for clinical practice. A basic study was made to consider the complex lung model and the changes of parameters with temperature in the future.