## 3 Results
### Numerical Simulation  
The heat transfer equation used in numerical simulation is Pennes heat transfer equation. The temperature distribution and ablation area under different ablation power (40 W, 50 W, 60 W) were studied. The calculation time is 300 s. Taking the 60 \({}^{\circ}\)C isotherm as the boundary of the ablation region, the long diameter (along the antenna direction) and short diameter (perpendicular to the antenna direction) of the ablation region were calculated. The simulation data are shown in Tables 9-11, and the temperature distribution is shown in Figures 8-10. Figure 7: Temperature curve of lung tissue at different locations of slot. (**a**) antenna slot (**b**) 5 mm away from the slot (**c**) 10 mm away from the slot (**d**) 15 mm away from the slot). \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Time/s**} & \multicolumn{2}{c}{**D/mm**} & \multicolumn{2}{c}{**Ds/mm**} \\ \cline{2-5}  & **Deflated** & **Inflated** & **Deflated** & **Inflated** \\ \hline
100 & 41.2 & 40.7 & 25.1 & 20.9 \\ \hline
200 & 45.1 & 43.4 & 29.0 & 23.7 \\ \hline
300 & 45.9 & 44.2 & 30.3 & 24.4 \\ \hline \hline \end{tabular}
\end{table} 
Table 10: Simulation data (ablation power 50 W). \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Time/s**} & \multicolumn{2}{c}{**D/mm**} & \multicolumn{2}{c}{**Ds/mm**} \\ \cline{2-5}  & **Deflated** & **Inflated** & **Deflated** & **Inflated** \\ \hline
100 & 44.9 & 44.9 & 26.8 & 23.2 \\ \hline
200 & 48.9 & 48.1 & 31.3 & 26.4 \\ \hline
300 & 50.9 & 48.7 & 32.9 & 27.2 \\ \hline \hline \end{tabular}
\end{table} 
Table 11: Simulation data (ablation power 60 W). Figure 8: Thermal field distribution of microwave ablation Power = 40 W, (a) inflated group; (b) deflated group. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Time/s**} & \multicolumn{2}{c}{**D/mm**} & \multicolumn{2}{c}{**Ds/mm**} \\ \cline{2-5}  & **Deflated** & **Inflated** & **Deflated** & **Inflated** \\ \hline
100 & 36.1 & 35.0 & 22.5 & 18.3 \\ \hline
200 & 39.9 & 37.8 & 26.1 & 20.9 \\ \hline
300 & 41.1 & 38.3 & 27.4 & 21.4 \\ \hline \hline \end{tabular}
\end{table} 
Table 9: Simulation data (ablation power 40 W). Figure 10: Thermal field distribution of microwave ablation (Power = 60 W, (**a**) inflated group; (**b**) deflated group). Figure 9: Thermal field distribution of microwave ablation (Power = 50 W, (**a**) inflated group; (**b**) deflated group). From the data in Tables 9-11, it can be seen that with the increase of ablation power and ablation time, the long and short diameters of the ablation area continue to expand, and the maximum temperature continues to rise. Under the same ablation power and ablation time, the long diameter, short diameter and maximum temperature of the deflated group were larger than those in the inflated group. From Figures 8-10, it can be seen intuitively that the shape of the microwave ablation area in the inflated group and the deflated group is elliptical, and the tissue temperature reaches the maximum value near the antenna slot. With increasing distance, tissue temperature gradually decreases and is eventually maintained at normothermia. In addition, it can be seen from the figure that under the same ablation parameters, the difference in the long diameter of the ablation area between the two experimental groups is not large, but the short diameter of the ablation area in the control group is significantly larger than that in the gas-filled group, resulting in a larger area and a better shape of the ablation area. tends to be circular, while the shape of the ablation area of the inflatable group tends to be elongated and oblate. Figure 11 shows the variation of the temperature at the slot of microwave antenna with ablation time under different ablation power. The tissue temperature at the slot increased rapidly in a short time, and decreased after about 60 s, and gradually became flat.