Stereotactic Positioning System: Towards a Mechanism Used in Thermal Ablation Therapy

Abstract

In microwave thermal ablation, placing the antenna on a specific coordinate is one of the most critical steps. Several stereotactic systems can place an instrument on a specific point with great accuracy. However, these systems are developed for neurosurgery; moreover, a stereotactic system used in microwave thermal ablation must not disturb the electromagnetic (EM) pattern generated by the antenna. A stereotactic positioning system was designed, built, and tested. Different types of materials were proposed to manufacture the proposed stereotactic system to locate the microwave antennas. The stereotactic system can displace the microwave antenna around the Z-axis and Theta-axis. Displacements were generated by stepper motors and controlled by the user through a graphical interface. The system tests consist of programming displacements along the two axes in steps of 5 mm on the Z-axis and 5 degrees on the Theta-axis. Results showed that the system is capable of moving using cylindrical coordinates over a 70 mm displacement with an average error of ±0.85 mm for sensors on the Z-axis, while in the Theta-axis it reaches 180∘ displacement with an error of ±2.64∘. A stereotactic microwave antenna positioning system was developed and preliminarily tested. This first system can already be used to evaluate antenna performance either in phantoms or ex-vivo tissue. Moreover, this system can be extrapolated to different parts of the human body and be adapted to the required dimensions.