System architecture of ultrasound-based real-time bone thickness determination for synergistically operated cutting tools

Cutting bone is one of the most important tasks in many surgical interventions (e.g. craniotomy, sternotomy). It is often performed close to critical structures such as central nervous structures and vessels with an inherent high risk of serious damage. One solution for cutting the bone safely is a hand-held synergistic bone cutting tool using a soft-tissue preserving saw and a sensor-controlled cutting tool, which allows an automatic adjustment of the cutting depth with respect to the local bone thickness. In this contribution an ultrasound-based concept for real-time bone thickness measurement using coded excitation and pulse compression is introduced. A first laboratory system has been implemented and evaluated in both transmission and impulse-echo mode using high attenuating bone mimicking material (40 dB/cm at 5 MHz) within the signal path. The first results have demonstrated the superiority of the system in terms of penetration depth compared to single burst technology. Furthermore, with a runtime of 11 ms for the entire signal processing chain, the system satisfies the real-time requirements of the hand-held sawing tool.