## 3 Results
### Radiation Dose of the Operating Staff  
The radiation doses of the neurosurgeon, operating nurse, and anesthesiologist were evaluated by assessing the ED via personal dosimeters that were always worn on top of the lead apron during surgery. The median ED of the surgeon was 11.00 (5.00-42.00) eVs during surgeries with iCT and 151.00 (77.00-329.00) eVs with C-arm fluoroscopy. Statistical analysis confirmed a significant difference in the surgeon's radiation dose between surgeries with iCT and C-arm fluoroscopy (Figure 2). In summary, the surgeon was exposed to a thirteenthd lower radiation dose on average when iCT was used instead of C-arm fluoroscopy.  
Figure 2: Effective dose of the surgeon during an MI-PLIF procedure. The ED of the surgeon (in eV) compared between surgeries assisted by iCT (\(n=23\)) or C-arm fluoroscopy (\(n=41\)). Extreme values are marked as “\(\bigstar\)” and outliers are marked as “\(\circ\)” on the boxplot. Significance (\(p<0.001\)) is indicated with “***” above the two boxplots.  
Similar to the ED of the surgeon, the ED of the operating nurse was significantly reduced during surgeries with iCT, compared to C-arm fluoroscopy (Figure 3). The median ED was 2.00 (1.00-6.75) \(\upmu\)Sv during surgeries with iCT and 8.00 (3.00-15.25) \(\upmu\)Sv during surgeries with C-arm fluoroscopy.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline  & **iCT (_n_ = 30)** & **C-Arm Fluoroscopy (_n_ = 45)** & _p-Value_ \\ \hline Age, in years (median (IQR)) & 58 (56–65) & 59 (49–72) & 0.701 \\ \hline BMI (median (IQR)) & 27 (23–30) & 26.5 (24.25–30) & 0.623 \\ \hline Gender (M/F) (\% male) & 11/19 (36.7) & 21/24 (46.7) & 0.391 \\ \hline Surgical indications (\% of patients) & & & 0.335 \\ \hline Discopathy & 3 (10.0) & 4 (8.9) & \\ \hline Listhesis & 16 (53.3) & 16 (35.6) & \\ \hline Stenosis & 0 (0.0) & 3 (6.7) & \\ \hline Hernia & 2 (6.7) & 1 (2.3) & \\ \hline Severe osteoarthritis of discs & 2 (6.7) & 1 (2.3) & \\ \hline Facet arthrosis & 0 (0.0) & 1 (2.2) & \\ \hline Other & 0 (0) & 1 (2.2) & \\ \hline Multiple disorders & 7 (23.3) & 18 (40.0) & \\ \hline Level fusion (no. [\% of patients]) & & & 0.093 \\ \hline Single level & 29 (96.7) & 38 (84.4) & \\ \hline Multi-level & 1 (3.3) & 7 (15.6) & \\ \hline Surgeon no. (\% of patients) & & & 0.000 \\ \hline Surgeon 1 & 19 (63.3) & 2 (4.4) & \\ \hline Surgeon 2 & 10 (33.3) & 9 (20.0) & \\ \hline Surgeon 3 & 1 (3.3) & 34 (75.6) & \\ \hline \hline \end{tabular}
\end{table}
Table 1: Basic characteristics of the study population per group.  
Figure 3: Effective dose (ED) of the operating nurse during an MI-PLIF procedure. The ED of the operating nurse (\(\upmu\)Sv) compared between surgeries assisted by iCT (_n_ = 24) or C-arm fluoroscopy (_n_ = 42). Extreme values are marked as “\(\star\)” and outliers are marked as “\({}^{\alpha_{0}}\)” on the boxplot. Significance (_p_ < 0.001) is indicated with “\({}^{***}\)” above the two boxplots.  
Furthermore, the ED of the anesthesiologist was also significantly lower during surgeries with iCT, compared to C-arm fluoroscopy (Figure 4). The median ED of the anesthesiologist was 0.00 (0.00-1.00) \(\upmu\)Sv with iCT and 1.00 (0.00-3.00) \(\upmu\)Sv with C-arm fluoroscopy.