# Stereotactic Positioning System: Towards a Mechanism Used in Thermal Ablation Therapy
## 5 Conclusions  
A stereotactic positioning system to locate microwave thermal ablation antennas over a human leg was developed. The standard size of the Mexican population was used to design the system. The total distance on the Z-axis was 70 cm, which can be considered large enough for most of the Mexican population. On the other hand, a diameter of  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**System** & \begin{tabular}{c} **Mean Accuracy** \\ **(mm)** \\ \end{tabular} & \
\begin{tabular}{c} **Standard** \\ **Deviation (mm)** \\ \end{tabular} &
\begin{tabular}{c} **Theta-Axis** \\ **Error (*)** \\ \end{tabular} & **Reference** \\ \hline This work & 0.85 & 0.25 & 2.71 & - \\ Cygnus PFS & 1.9 & 0.7 & - & [31] \\ SMN system & 2.61 & 0.99 & - & [31] \\ ISG viewing & 1.67 & 0.43 & - & [31] \\ \hline \hline \end{tabular}
\end{table}
Table 2: Mean accuracy comparison with commercial frameless systems.  
Figure 10: Graphical user interface implemented for preliminary tests of the stereotactic positioning system, showing the sections (1) control displacement, (2) display coordinates, and (3) data export.  
40 cm was considered. Infrared sensors were adapted to track and measure the system movements; in the Z-axis working distance, the displacement measured error was 0.85 mm to accurately position microwave antennas for the thermal ablation technique. Moreover, this system allows the operator to either locate or to keep the antenna in the same location during the whole treatment time. The stereotactic system serves for placing micro-coaxial antennas over a human leg, but it can be easily modified to other body parts by adapting the measurements to specific dimensions. It is important to address the fact that the proposed stereotactic positioning system was designed specially to be used as a tool in the thermal ablation therapy. Therefore, all the materials used to build it were chosen in order to reduce as much as possible the interference with the EM energy generated by the micro-coaxial antenna. To our understanding, because the temperature patterns, strongly related to the EM patterns, generated by the micro-coaxial antenna are really focused on the body region (\(\approx\)2 cm\({}^{2}\)) that must be treated, the antenna performance will not be modified by the few metallic components at the stereotactic system. However, to completely validate this information, some experimental tests, considered as a future work, must be done. The next step is a validation of the effect of the system on the electromagnetic field first by numerical simulations and then by measuring the electromagnetic field in conditions similar to the surgery environment. To perform communication between the computer and the stereotactic system, a graphic interface was developed. The interface controls the system's position automatically by using python and StandardFirmeta. The interface provides a method to store the system position and sensor data. The repeatability of the positioning system was tested the measured error was lower than 1%, making it comparable to the actual commercial systems.  
Conceptualization, C.J.T.-R. and J.J.A.F.C.; methodology, J.M.M. and G.L.H.; software, J.M.M., C.J.T.-R., G.L.H. and J.J.A.F.C.; validation, J.M.M., C.J.T.-R. and J.J.A.F.C.; formal analysis, C.J.T.-R., A.M.S. and J.J.A.F.C.; investigation, J.M.M. and G.L.H.; resources, C.J.T.-R., A.M.S. and J.J.A.F.C.; data curation, G.L.H. and A.M.S.; writing--original draft preparation, C.J.T.-R. and J.J.A.F.C.; writing--review and editing, J.M.M., C.J.T.-R., G.L.H. and J.J.A.F.C.; supervision, C.J.T.-R. and J.J.A.F.C. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
This work does not contain any studies with human participants performed by any of the authors.  
Data availability Statement: Data are available from the authors under request.  
We thank [PERSON] for technical support.  
The authors declare no conflict of interest.