# Medical Augmented-Reality Visualizer for Surgical Training and Education in Medicine
## 3 Results
### System Validation  
An initial validation of MARVIS was conducted as a trial involving pricing internal structures of the liver phantom (Figure 16) using either phantom image data displayed in a traditional way on an external LCD monitor (control experiment) or structures being projected (Figure 12) directly onto the phantom's surface (test experiment). Figure 16: Setup and validation of MARVIS system. (**A**)—Experimental setup showing author [PERSON] preparing the system for tests with the HdTM marker on his forehead. (**B**)—Performance of validation tests. (**C**)—Detailed projection view. The green border indicates that pose detection was paused. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \(X_{0}\) & \(Y_{0}\) & \(Z_{0}\) & \(X_{1}\) & \(Y_{1}\) & \(Z_{1}\) & \(\Delta X\) & \(\Delta Y\) & \(\Delta Z\) \\ \hline
**[mm]** & **[mm]** & **[mm]** & **[mm]** & **[mm]** & **[mm]** & **[mm]** & **[mm]** & **[mm]** \\ \hline
339.01 & \(-\)135.37 & 968.48 & 339.60 & \(-\)135.44 & 970.28 & 0.59 & 0.08 & 1.80 \\
46.13 & 174.12 & 588.10 & 46.24 & 174.62 & 592.71 & 0.11 & 0.50 & 4.61 \\
28.39 & \(-\)128.10 & 578.11 & 28.41 & \(-\)128.06 & 582.33 & 0.01 & 0.04 & 4.22 \\
204.44 & 137.02 & 632.78 & 205.57 & 137.01 & 637.43 & 1.14 & 0.01 & 4.65 \\
206.63 & \(-\)148.44 & 629.07 & 207.64 & \(-\)148.42 & 633.28 & 1.01 & 0.02 & 4.21 \\
236.37 & 19.10 & 682.92 & 237.92 & 18.94 & 687.45 & 1.55 & 0.15 & 4.53 \\
45.74 & 21.10 & 877.70 & 45.91 & 20.99 & 881.10 & 0.17 & 0.11 & 3.39 \\ \(-\)118.27 & 63.50 & 1069.90 & \(-\)118.63 & 63.38 & 1072.95 & 0.35 & 0.12 & 3.05 \\ \(-\)270.32 & 69.22 & 1234.31 & \(-\)270.96 & 69.11 & 1237.19 & 0.64 & 0.10 & 2.88 \\ \(-\)186.02 & \(-\)257.16 & 1080.75 & \(-\)186.49 & \(-\)257.02 & 1082.93 & 0.46 & 0.14 & 2.18 \\ \(-\)195.27 & 228.51 & 1040.83 & \(-\)196.05 & 228.67 & 1044.49 & 0.78 & 0.17 & 3.66 \\ \hline \multicolumn{8}{c}{Average error} & 0.69 & 0.21 & 3.37 \\ \hline \multicolumn{8}{c}{Median error} & 0.63 & 0.13 & 3.53 \\ \hline \multicolumn{8}{c}{Each row corresponds to a 3D point in the global coordinate system. (\(X_{0}\),\(Y_{0}\),\(Z_{0}\)) describes the position of the first calculation of the 3D reprojection of 2D pixels onto the global coordinate system. (\(X_{1}\),\(Y_{1}\),\(Z_{1}\)) describes the result of projecting (\(X_{0}\),\(Y_{0}\),\(Z_{0}\)) onto the camera pixels and their reprojection to the 3D coordinate system.} \\ \end{tabular}
\end{table} 
Table 3: _Cont._  
Figure 15: Part of test points to calculate the head-tracking accuracy. Presented eight points are near the edges of the calibrated volume. The total of 25 students (12 males and 13 females, mean age, 23.12 years; SD, 1.27 years) from the faculties of medicine at the Medical University of Warsaw took part in the validation. Additionally, three experienced male surgeons performed the same test (mean age, 43.66 years; SD, 7.57 years). Given the small number of participating surgeons, we analyzed the data from all the participants together. For each participant, the experiment was carried out as follows:  
1. Control experiment: Author [PERSON] selected an internal structure from the 3D model displayed on the external monitor. The 3D model was generated using CT data of the first phantom (two phantoms with different internal structure shapes were used for each participant of the experiment in order to avoid the influence of the user remembering the particular case). The participant was asked to pick the structure in the first liver phantom with a syringe probe by looking at the 3D model. The 3D model could be rotated accordingly using a computer keyboard. The time to complete the task was measured manually by the test supervisor until the participant informed task accomplishment. 2. Test experiment: Author [PERSON] selected an internal structure projected by the MARVIS system onto the second phantom. The participant was asked to pick the structure with the syringe probe.