Positioning System of Therapeutic Device by Ultrasound Image Guide for Minimally Invasive Surgery

Ultrasound has been widely applied to clinical purpose of therapy as well as diagnosis. For ultrasound therapy, accurate positioning of therapeutic ultrasound field is required. To address the issue, we will propose a robotic system for sound field positioning for an ultrasound guidance. The system consists of an ultrasound probe, a 6-dof robot grasping a therapeutic device, an optical tracking device, and intra-operative planning software. The robot, which was designed to form a compact parallel link structure, was composed of three serial-link manipulators and a device grasping parts. In addition, respective links and the grasping part were connected using magnetic ball joints for safety. The system enables the therapeutic device follows to a probe based on intra-operative plan on an echogram. In this paper, basic performance of the developed system was validated. The following errors and latency to the probe were 2.24 mm, 0.76 degree, and 50 ms, respectively. Also, the positioning errors between the plans and actual positions based on echograms were 2.22 mm and 0.06 degree. The results demonstrate the system has a great potential for targeting a therapeutic device under the ultrasound guidance for ultrasound therapy.