4.6. Summary

• Tracking devices are an important component of image-guided systems as they allow us to track the position of different devices during a surgical procedure.

• There are three main types of tracking used in surgical room: mechanical, optical and electromagnetic.

• Mechanical digitisers transform a mechanical movement into a digital measurement. Widely used in the robotics field (e.g., DaVinci’s kinematic tracking).

• Optical tracking requires a line-of-sight between the camera and the object tracked but provides a high accuracy and precision (approx. 0.25 mm accuracy).

• Electromagnetic tracking does not need to have a line-of-sight but it has other sources of errors such as a field distortion due to ferromagnetic materials placed nearby (approx. 0.7 mm accuracy).

• There are also common errors such as the so-called lever-arm, static errors and dynamic errors.

• The selection of a tracking system will depend on the surgical procedure and the expected accuracy.