# Simulation Study of Microwave Ablation of Porous Lung Tissue
## 3 Results
### Effect of Tumor Porosity  
Since the human body is a thermostatic regulating system, the temperature of the blood is automatically regulated during microwave ablation to maintain a stable value of body temperature [27]. On the one hand, the core temperature of the arterial blood is changed to achieve the purpose of regulating the blood temperature, and on the other hand, the porosity of the biological tissue is changed. This is achieved by increasing the porosity of biological tissues at higher temperatures and decreasing the porosity of biological tissues at lower temperatures. The change in the porosity of biological tissues further affects the change in their effective thermal conductivity, thus achieving the purpose of regulating body temperature [26]. Meanwhile, tissues under different physiological conditions have different porosities, which can affect the temperature of tissues during microwave ablation and influence the final ablation effect. Therefore, it is of great practical significance to study the effect of tumor tissue porosity on ablation.  
Figure 4a-c show the temperature distribution of porous lung tissue with tumor tissue porosities of 0.5, 0.6, and 0.7, at P = 10 W and t = 360 s, respectively [21]. It can be seen from the figure that tumor tissues with different porosities have the same temperature distribution, but there are some temperature differences. As the tumor porosity increases, the maximum temperature reached by the ablated tissue gradually decreases. From the figure, we can see that the transverse diameter of the ablation area is decreasing. We also noticed that when the tumor was 2.0 cm in diameter, the tumor could not be completely ablated, regardless of the porosity (0.5,0.6, or 0.7, P = 10 W, t = 360 s).  
Table 6 shows the maximum temperature, ablation zone transverse and longitudinal diameter, and ablation volume of tumors with different porosities. The maximum temperature decreased from 95.3 \({}^{\circ}\)C to 83.9 \({}^{\circ}\)C when the tumor porosity increased from 0.5 to 0.7, the transverse and longitudinal diameter of the ablation zone both decreased; the transverse diameter from 1.23 cm to 0.62 cm, and the longitudinal diameter from 2.02 cm to 1.82 cm. At the same time, the transverse diameter decreased more than the longitudinal diameter.  
Figure 4: Temperature distribution of porous lung tissue at different porosity of tumor (P = 10 W, t = 300 s, d = 2.0 cm, \(\phi_{l}\) = 0.7): (a) \(\phi_{l}\) = 0.5 (b) \(\phi_{l}\) = 0.6 (c) \(\phi_{l}\) = 0.7.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Tumor Diameter (cm)**} & \multirow{2}{*}{**Maximum Temperature (\({}^{\circ}\)C)**} & \multicolumn{2}{c}{**Ablation Zone (cm)**} & \multirow{2}{*}{**Ablation Volume (cm\({}^{3}\))**} \\ \cline{3-3} \cline{5-5}  & & **Tansverse Diameter (cm)** & & **Longitudinal Diameter (cm)** \\ \hline
1.4 & 89.4 & 1.30 & 1.82 & 2.34 \\
2.0 & 87.3 & 0.92 & 1.88 & 2.40 \\
2.6 & 86.1 & 0.76 & 2.19 & 2.52 \\ \hline \hline \end{tabular}
\end{table}
Table 5: Ablation temperature, ablation area and ablation volume for different diameter tumors.  
The ablation volume decreased from 2.94 cm\({}^{3}\) to 1.80 cm\({}^{3}\). The greater the porosity is, the greater the risk of incomplete ablation of the tumor. Therefore, when tissue lesions exist, the effect of the tissue porosity change on the ablation effect should be considered and the ablation parameters should be adjusted in time.