## 3 Results  
CT studies were performed in accordance with the parameters outlined in Table 1-the total examination time was: 30 min \(\pm\) 5 min. The average segmentation time, together with virtual planning and optimization of the 3D model, was 180 min \(\pm\) 11 min. The models were then printed according to the parameters outlined in Table 2. The average printing time was 600 min \(\pm\) 60 min (10 h \(\pm\) 1 h)-The printing was carried out overnight to make the best use of the available time. Removal of support materials required 180 min. \(\pm\) 10 min and the pre-contouring stage was 30 min \(\pm\) 5 min. Model cleaning and sterilization lasted 120 min. Sterile plates were delivered to the operating room on the morning of the operation. Total time from CT scan to sterile pre-contoured plate (details provided in Table 3), \begin{table}
\begin{tabular}{c c} \hline \hline \multicolumn{2}{c}{**Computed Tomography Scanning Protocol**} \\ \hline
**NECT** & Non-contrast Enhanced Computed Tomography \\ \hline
**Region** & Pelvis \\ \hline \multirow{5}{*}{**Image reconstruction**} & Reconstruction algorithms (Kernels): \\  & Used in the study \\  & GE: Standard, Bone, Bone Plus; \\  & Siemens: B30f, B30s, B60s, B70s; \\  & Recommended for other CT scanners \\  & Philips: Standard, Sharp, Detail (B, C, D, E, L); \\  & Toshiba: FC08, FC18, FC30, Fc35; \\ \hline
**Slice Thickness** & \(\leq\)1.0 mm (isometric voxel) \\ \hline
**Resolution** & 512 \(\times\) 512 \\ \hline
**Pitch** & \(\leq\)1.0 \\ \hline
**Gantry Tilt Angle** & 0 \\ \hline
**Data Format** & Uncompressed DICOM files \\ \hline \hline \end{tabular}
\end{table} 
Table 2: CT scan parameters. Figure 5: (Patient 3) (**a**) Mirrored uninjured hemipelvis with reconstruction plates (**b**) (Patient 4) Post-operative X-ray image (scale bar = 200 mm). \begin{table} \begin{tabular}{c c} \hline \hline \multicolumn{2}{c}{**3D Printing Parameters**} \\ \hline
**Printing temperature** & 205 \({}^{\circ}\)C \\ \hline
**Build plate temperature** & 60 \({}^{\circ}\)C \\ \hline
**Layer high** & 0.2 mm \\ \hline
**Infill** & 60\% \\ \hline
**Support material** & Polyvinyl alcohol (PVA) \\  & (Ultimaker B.V, Utrecht, The Netherlands) \\ \hline \hline \end{tabular}   
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models. Essentially 3D printers can be divided into two groups-high-end industrial printers and budget, desktop printers. Industrial 3D printers are expensive and usually require specialized personnel and infrastructure to operate them. At the same time, budget printers have not always been capable of printing accurate three-dimensional models. However, a large number of manufacturers active in this industry sector and recent advances, have resulted in low-cost 3D printers that can produce relatively high-quality models. The Fast-Track-Protocol assumes that medical staff, in the form of a multidisciplinary team, will take a Do It Yourself (DIY) approach and create 3D objects using open source, software for converting CT data and then build them using a low-cost FFF/FDM 3D printer, within 2 working days. This will not delay any surgical treatment, as on average patients are operated on 3-5 days from the moment of injury (optimal time is up to 7 days following trauma). Data from the literature [19] show two basic approaches to preparing and using 3D printed templates for pre-contouring fixation plates (Figures 3-5). The first approach focuses on 3D printing only, whilst the second uses virtual planning and fragment reduction, followed by 3D printing. The 3D printing only method greatly reduces the number of procedures required; as a result, it is a much faster process. However, such an approach assumes that the human bony pelvis is symmetric [23] and that the mirrored _uninjured_ contralateral hemipelvis can serve as a template for pre-contouring reconstruction plates [14,24]. On the other hand, virtual fracture reduction that consists of repositioning virtual bone fragments is inaccurate and unpredictable.