## 3 Results
### Radiation Dose Received by Organs at Risk (OARs)  
The dose distributions of the 3D-Plan, 4D-Plan, and MF-Plan on CT images in radiotherapy are shown in Figure 3. The relative volume of the lung receiving a dose above 5 (V\({}_{5}\)), 10 (V\({}_{10}\)), and 20 (V\({}_{20}\)) Gy; the mean radiation dose of the heart; and the maximum radiation dose of the spinal cord were used to evaluate the radiation dose received by OARs. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Patient Number**} & \multicolumn{4}{c}{**Homogeneity Index**} & \multicolumn{4}{c}{**Conformity Index**} \\ \cline{2-7}  & **3D-Plan** & **4D-Plan** & **MF-Plan** & **3D-Plan** & **4D-Plan** & **MF-Plan** \\ \hline
1 & 1.05 & 1.06 & 1.05 & 1.00 & 0.99 & 1.00 \\
2 & 1.05 & 1.05 & 1.05 & 1.00 & 1.00 & 1.00 \\
3 & 1.05 & 1.04 & 1.05 & 1.00 & 1.00 & 1.00 \\
4 & 1.05 & 1.05 & 1.05 & 1.00 & 1.00 & 0.99 \\
5 & 1.07 & 1.06 & 1.07 & 0.99 & 0.99 & 0.99 \\
6 & 1.05 & 1.05 & 1.04 & 1.00 & 1.00 & 1.00 \\
7 & 1.05 & 1.05 & 1.05 & 1.00 & 1.00 & 1.00 \\
8 & 1.05 & 1.05 & 1.05 & 1.00 & 0.99 & 1.00 \\
9 & 1.05 & 1.05 & 1.05 & 1.00 & 1.00 & 1.00 \\
10 & 1.05 & 1.05 & 1.04 & 1.00 & 1.00 & 1.00 \\
11 & 1.04 & 1.05 & 1.05 & 1.00 & 1.00 & 1.00 \\
12 & 1.05 & 1.05 & 1.04 & 0.90 & 1.00 & 1.00 \\
13 & 1.05 & 1.05 & 1.04 & 1.00 & 1.00 & 1.00 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Homogeneity index (HI) and conformity index (CI) of individual patients under different treatment plans. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Patient Number**} & \multicolumn{4}{c}{**V\({}_{95\%}\) (\%)**} & \multicolumn{4}{c}{**D\({}_{\text{max}}\) (\%)**} \\ \cline{2-7}  & **3D-Plan** & **4D-Plan** & **MF-Plan** & **3D-Plan** & **4D-Plan** & **MF-Plan** \\ \hline
1 & 99.8 & 99.8 & 99.9 & 104.8 & 104.7 & 104.8 \\
2 & 99.7 & 98.9 & 99.9 & 104.9 & 104.7 & 105 \\
3 & 99.9 & 99.9 & 99.9 & 104.9 & 104.4 & 104.8 \\
4 & 99.9 & 99.9 & 99 & 105 & 105 & 104.6 \\
5 & 99.4 & 99.3 & 98.6 & 104.9 & 104.8 & 104.6 \\
6 & 99.9 & 99.8 & 99.9 & 104.8 & 104.9 & 104.4 \\
7 & 99.9 & 99.9 & 99.9 & 104.5 & 104.5 & 104.4 \\
8 & 99.8 & 99.3 & 99.6 & 104.7 & 104.5 & 104.6 \\
9 & 99.9 & 99.8 & 99.8 & 104.4 & 104.4 & 104.1 \\
10 & 99.3 & 99.8 & 99.9 & 104.4 & 104.3 & 104.1 \\
11 & 99.9 & 99.9 & 99.8 & 103.6 & 104.9 & 104.9 \\
12 & 99.9 & 99.9 & 99.8 & 104.6 & 104.7 & 104.5 \\
13 & 99.9 & 99.8 & 99.9 & 104.6 & 104.5 & 104.4 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Percentage volume that received at least 95% of the prescription dose (V\({}_{95\%}\)) and the maximum target dose (D\({}_{\text{max}}\)) of the patients under the different treatment plans for respiratory-gated radiation therapy. Among the three plans, the radiation dose received by the lung was of the order 3D Plan > 4D Plan > MF Plan, and the phenomenon was seen when V\({}_{5}\), V\({}_{10}\), or V\({}_{20}\) were used as the criterion (Figure 4). For the 3D Plan, 4D Plan, and MF Plan, the median values (and ranges) of the V\({}_{5}\) were 30.6% (56.6-11.5%), 26.1% (54.4-8.1%), and 21.6% (5.2-6.9%), respectively; those of the V\({}_{10}\) were 20.6% (41.8-7.8%), 16.2% (36.4-5.6%), and 14.1% (37.8-5.2%), respectively; and those of the V\({}_{20}\) were 15.6% (30.3-5.5%), 13% (28.1-3.8%), and 10.5% (27.4-3.2%), respectively. The MF Plan had the lowest mean radiation dose received by the lung, followed by the 4D Plan (Figure 5). For the 3D Plan, 4D Plan, and MF Plan, the median values (and ranges) were 810 cGy (1554-348 cGy), 622 cGy (1396-238 cGy), and 540.4 cGy (1353-223 cGy), respectively. Comparison of the three plans revealed that the MF Plan resulted in the lowest mean radiation dose of the heart, followed by the 4D Plan (Figure 6). For the 3D Plan, 4D Plan, and MF Plan, the median values (and ranges) were 906 cGy (1648-30 cGy), 722 cGy (1593-15 cGy), and 616 cGy (1618-11 cGy), respectively.