## 3 Results
For a comparative evaluation of the RSF, the standard lead shielding performance was obtained under the same experimental conditions shown in Table 5.  
The shielding performance of the RSFs made of BaSO\({}_{4}\), Bi\({}_{2}\)O\({}_{3}\), and WO\({}_{3}\) are shown in Figure 4; that of the shielding product improved owing to the thicker layer, and it differed in the order of WO\({}_{3}\), Bi\({}_{2}\)O\({}_{3}\), and BaSO\({}_{4}\). Particularly, at 0.2 mm, higher energy corresponded to a larger difference in the shielding ratio of the BaSO\({}_{4}\) component. The shielding ratio refers to the degree of shielding performance, which is obtained using the formula \((1-w/w1)\times 100\), where \(w\) denotes the case with the shielding material and \(w1\) denotes the case without the shielding material. When WO\({}_{3}\) was used, it showed an almost stable shielding performance for a thickness of 0.6 mm. Shielding was not always 100%; that is, the material thickness was fixed at three different values, depending on the shielding ratio and the material used. A shielding ratio of 100% for tungsten indicates that 100% shielding is achieved with no penetration at a low energy of 60 kV. As a result, as shown in the graph, the same shielding tendency is shown by the change in the tube voltage. Figure 4 shows that the shielding ratio decreases with increasing energy. However, the difference in the ratio varies depending on the material owing to the difference in porosity. This difference is low for the low-porosity WO\({}_{3}\) composite and high for the BaSO\({}_{4}\) shield. There was a difference in the individual shielding ability of the RSF manufactured for each material, and the shielding performance also changed with the thickness. As a numerical estimate, it can be expressed by the transmission dose and lead equivalent, as presented in Table 6[16]. The RSF using BaSO\({}_{4}\)--based on the 0.6 mm RSF--corresponds to 0.5 mm Pb of the lead equivalent, 0.4 mm Pb of the Bi\({}_{2}\)O\({}_{3}\), and 0.1 mm Pb of the WO\({}_{3}\). Figure 4: Shielding ability as a function of film thickness. (**a**) Shielding performance of 0.2 mm shielding films; (**b**) shielding performance of 0.4 mm shielding films; (**c**) shielding performance of 0.6 mm shielding films. WO\({}_{3}\): tungsten oxide powder; Bi\({}_{2}\)O\({}_{3}\): bismuth trioxide; BaSO\({}_{4}\): barium sulfate. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Tube Voltage (kV)** & **Thickness (mm)** & **None** & **0.25** & **0.30** & **0.35** & **0.40** \\ \hline
60 & 15.00 & 0.10 & 0.05 & 0.01 & 0.002 \\
80 & 39.82 & 2.15 & 1.52 & 0.82 & 0.04 \\
100 & 60.04 & 5.09 & 3.86 & 2.81 & 1.95 \\
120 & 80.20 & 9.26 & 7.10 & 5.14 & 3.01 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Standard lead penetration dose (unit: mR). The individual shielding ability of the RSF prepared for each material varied, and the shielding performance also depended on the thickness. For numerical estimation, the penetration dose can be measured to show the lead equivalent. Therefore, an RSF using BaSO\({}_{4}\) based on 0.6 mm thickness corresponds to 0.5 mm Pb of lead equivalent, and the RSF using Bi\({}_{2}\)O\({}_{3}\) and WO\({}_{3}\) correspond to 0.4 and 0.1 mm Pb, respectively. It was found that the correlation between the porosity and the shielding ratio showed a decreasing trend, as seen Figure 5. However, as the strength increased, the shielding ratio improved.