Firstly, the system architecture based on the current medical workflow was a challenge. It needed to minimize the barriers to being used by the doctor, both literally and figuratively. A second challenge was the design factor. The entire system, including arm and head, needed to fit in the (tight) space between the patient and the CT scanner’s ring.

However, the biggest hurdle was CT compatibility. The bulk of the system would enter the scanner’s X-ray field but should not disrupt the imaging. That meant that the usual materials like steel, copper and titanium were not an option. We worked with several suppliers including Ceratec (ceramics) and Futura Composites to develop alternatives. Varieties of materials were used in the components, such as composites (for rigid construction parts and flexible elements), ceramics (for highly stressed precision parts and ball bearings), Dyneema fibers (for rotating cable drives), carbon nanotubes (for power wires and switches) and plastic optic fibers (to read out encoder positions remotely).

These solutions imparted high rigidity to the construction, minimizing any transmission play. The result is a system which can guide the needle correctly and precisely, with a margin of error of less than 2 mm at a depth of 25 cm. This means the patient suffers only minimal tissue damage, the medical team can complete the procedure more quickly (and thus more economically), and the doctor remains ‘in control’.