# RF Exposure Assessment for Various Poses of Patient Assistant in Open MRI Environment
## 3 Results and Discussion
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Scenario** & \multicolumn{2}{c}{**Patient ([PERSON])**} & \multicolumn{2}{c}{**Patient Assistant (Duke)**} \\ \hline  & 1 g & 10 g & 1 g & 10 g \\ \hline S\({}_{\text{ab}}\) & 1.6500 & 0.8279 & - & - \\
1 & 1.6663 & 0.8361 & 0.00048 & 0.00024 \\
2 & 1.6263 & 0.8477 & 0.00019 & 0.00009 \\
3 & 1.5992 & 0.8336 & 0.00264 & 0.00141 \\
4 & 1.5811 & 0.8242 & 0.26537 & 0.082449 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Peak spatially averaged SAR (W/kg) in Thelonious (patient) and Duke (patient assistant) according to head RF coil (input power = 1 W). patient assistant and (2) the lack of electrical contact points between the patient assistant and patient. Meanwhile, when the patient assistant made direct contact with the patient as in scenarios 3-5 (see Figure 5c-e), the hot-spots were clearly observed at the patient assistant's hand because a substantially induced electrical current was driven through the patient assistant's arms, forming electrical closed loops. For this reason, compared with scenarios 1 and 2, the overall SAR levels of the patient assistant were significantly increased in scenarios 3-5. The external magnetic field generated by the RF coils was coupled to the \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Scenario** & \multicolumn{2}{c}{**Patient ([PERSON])**} & \multicolumn{2}{c}{**Patient Assistant ([PERSON])**} \\ \hline  & 1 g & 10 g & 1 g & 10 g \\ \hline S\({}_{\text{ab}}\) & 0.8649 & 0.5684 & - & - \\
1 & 0.8744 & 0.5746 & 0.00017 & 0.00007 \\
2 & 0.8752 & 0.5752 & 0.00007 & 0.00003 \\
3 & 0.8713 & 0.5726 & 0.03635 & 0.01294 \\
5 & 0.8592 & 0.5665 & 0.227301 & 0.15065 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Peak spatially averaged SAR (W/kg) in [PERSON] (patient) and [PERSON] (patient assistant) according to body RF coil (input power = 1 W). Figure 6: The 1 g SAR distributions of the patient assistant ([PERSON]) when [PERSON] was the patient for different scenarios: (**a**) 1, (**b**) 2, (**c**) 3, (**d**) 4, (**e**) 5 (same dB and color scale). \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Scenario** & \multicolumn{2}{c}{**Patient ([PERSON])**} & \multicolumn{2}{c}{**Patient Assistant ([PERSON])**} \\ \hline  & 1 g & 10 g & 1 g & 10 g \\ \hline S\({}_{\text{ab}}\) & 1.2795 & 0.7457 & - & - \\
1 & 1.1311 & 0.7638 & 0.00029 & 0.00016 \\
2 & 1.2887 & 0.7564 & 0.00012 & 0.00006 \\
3 & 1.1000 & 0.6771 & 0.06978 & 0.03815 \\
5 & 1.0445 & 0.6828 & 0.94568 & 0.41197 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Peak spatially averaged SAR (W/kg) in [PERSON] (patient) and [PERSON] (patient assistant) according to RF body coil (input power = 1 W). closed induction loop formed by the arms of the patient assistant. This therefore caused an induction current along the patient assistant's arm, and thus a notably increased SAR in the patient assistant's body was observed. The level of hot-spot tended to have a relationship depending on the formation of the loops formed by the body parts of the patient assistant and patient or gaps between them. According to [PERSON]'s law, the magnetic field induced an electromotive force in these effective conduction loops, thereby generating an electrical current proportional to the area of the loop and magnetic flux. Larger loops result in a higher induction current. Therefore, scenario 5 produced higher SAR levels in the patient assistant than scenarios 4 and 3, because the largest loop size was formed under scenario 5. In most cases, the SAR levels of the patient assistant were much lower than those of the patient's head or body, except under scenario 5, which had the largest loop formed by the patient assistant's arm.