Tobias Fürtjes

Concept and evaluation of a synergistic controlled robotic instrument for trepanation in neurosurgery

A robotic instrument which synergistically cooperates with the surgeon for opening the skull in neurosurgery is proposed. To reduce frequent complications of this intervention, tear of the dura mater and bad reintegration of the skull bone a soft tissue preserving saw is combined with automatic depth regulation on the basis of a priori acquired medical imaging data (CT/MRI). By fusing the individual capabilities of the surgeon and a robotic device, it is possible to design an instrument which is significantly smaller than a fully autonomous system. The acceptance is enhanced by the integration of the surgeon into the process with direct control over the procedure. During the intervention, the instrument is manually guided by the surgeon on a freely defined trajectory. To be able to control this instrument, a method for real-time depth regulation, medical imaging data pre-processing and reduction as well as appropriate interfaces for the surgeon have been developed. In an experimental setup with phantom skull caps the system has been evaluated and has shown promising results, with a mean error of 0.62mm. Future work will include a detailed analysis of the persisting errors, integration of different sensors to control the instrument and preclinical trials.

Evaluation of a synergistically controlled semiautomatic trepanation system for neurosurgery

One of the most common procedures in neurosurgery is the trepanation of the skull. In this paper, a synergistically controlled handheld tool for trepanation is introduced. This instrument is envisioned to reduce problems of dural tears and wide cutting gaps by combining a soft tissue preserving saw with an automatic regulation of the cutting depth. Since usability and safety of the semi-automatic handheld device are of utmost importance, the complex interaction between the user and the system has been analyzed extensively. Based on prospective usability evaluation the user interaction design and the corresponding user-interface were developed. The compliance with the relevant factors effectiveness, efficiency, error tolerance, learnability and user satisfaction was measured in user-centered experiments to evaluate the usability of the semiautomatic trepanation system. The results confirm the user interaction design of the semiautomatic trepanation system and the corresponding safety strategy. The system seems to integrate itself smoothly into the existing workflow and keeps the surgeon aware of the process.

Optical sensors for a synergistically controlled osteotomy system

Cutting bone is an important task in many surgical interventions (e.g. orthopedic surgery, neurosurgery). However it is often performed close to critical structures such as vessels or central nervous structures with an inherent high risk of serious damage. In this paper a concept for improving the safety of these surgical procedures is presented, by combining a soft tissue preserving saw with optical sensors in a semiautomatic controlled instrument. A real-time system acquires and analyses the data from an optical sensor and allows a indirect detection of the actual local bone thickness and the automatic adjustment of the sawing depth. To determine material characteristics (e.g. soft tissue, bone) a color sensor has been used in combination with a hysteresis controller. To show the feasibility of this concept a simple prototype has been built and evaluated with bone samples and parts of an artificial Sawbones skullcap. The system performed well with different materials and geometries, but further research has to be directed towards sensor integration and dynamic performance.