## 4 In Vivo Experiment Results
### Pig Right Renal Artery  
In the case of the right renal artery selection experiment, the starting and target points were set as shown in Figure 12. The selection of the right renal artery was also performed three times for each target and for each master device per operator. Compared to the hepatic and splenic artery experiments, it was easier to approach the target points in the right renal artery experiment. The results of the measurement of the radiation exposure to operators during the conventional and robotic VI procedures for the right renal artery are shown in Figure 13. In the conventional procedure for the right renal artery target 1, the radiation exposure was measured as 2.84 \(\pm\) 0.91 eV, whereas that for the robotic procedure was 0.08 \(\pm\) 0.04 \(\upmu\)Sv. Further, for the right renal artery target 2, the radiation exposure doses of the operator were measured as 2.61 \(\pm\) 0.87 eV and 0.06 \(\pm\) 0.02 \(\upmu\)Sv for the conventional and robotic VI procedures, respectively. In the right renal artery target 1 and target 2 experiments, it \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**MASTER DEVICE**} & **Number of Retractions** & **Number of Retractions** & **Moving Distance for** & **Moving Distance for** \\  & **of Surgical Instruments** & **of Surgical Instruments** & **Target 1 [meter]** & **Target 2 [meter]** \\  & **for Target 1** & **for Target 2** & & \\ \hline
2 DOFs ergonomically & & & & \\ designed master device & 6 & 8 & 4.16 & 4.57 \\ \hline
2 DOFs joystick-type & & & & \\ master device & 15 & 21 & 5.27 & 10.51 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Moving distance and the number of retractions of surgical instruments (mean) for hepatic artery and splenic artery. Figure 12: Starting and target points of pig right renal artery experiments. was observed that the robotic VI procedure reduced the radiation exposure by about 97% compared to the conventional procedure. For the usability tests, we employed two measures in this study: NASA-TLX and SUS score. The results of the overall workload scores based on the NASA-TLX and the system integration score evaluations based on the SUS score are summarized in Table 3.  
The operators reported higher NASA-TLX scores for both target 1 and target 2 of the right renal artery when using the 2 DOFs joystick-type master device, implying that this device is physically and mentally harder to operate. Further, higher SUS scores were reported for target 1 and target 2 of the right renal artery when using the 2 DOFs ergonomically designed master device. However, the differences in the SUS scores of the right renal artery experiments were smaller than those of the SUS scores in the hepatic artery experiments. Fewer differences were observed between the NASA-TLX score of each target on the right renal artery. In the case of the 2 DOFs joystick-type master device, the mean score was about 72 points for target 1 and target 2. In the SUS score evaluation criterion, the 2 DOFs joystick-type master device was scored as \"acceptable\". In addition, in the case of the 2 DOFs ergonomically designed master device, SUS scores of about 76 points were obtained for both target 1 and target 2 of the right renal artery. Thus, the scores of the 2 DOFs ergonomically designed master device were also \"acceptable\". Thus, the 2 DOFs ergonomically designed master device outperformed the 2 DOFs joystick-type device in terms of user work intensity and system integration. In addition, Table 4 shows the average of moving distances of the two master devices and the number of retractions of surgical instruments during the process of selecting blood vessels to reach the targets. Figure 13: Measurement results of the radiation exposure to operators during conventional and robotic VI procedures. The measured radiation exposure during the procedure for (**a**) right renal artery target 1; and (**b**) right renal artery target 2.