体表面接触を考慮した超音波治療デバイスの位置制御システムの開発

抄録

Ultrasonic thrapy such as high intensity focused ultrasound and acoustic drug/gene delivery has a potential to provide minimal invasive and safe procedure. However, positioning of an ultrasound transducer accurately on a patient body is required. This paper provides a robotic approach to control position of a transducer and contact condition with a body surface. The robot which consists of three parallel links has six degrees of freedom. To control contact force with body surface, a six-axis force sensor is attached at the robot end-effector. The system has following three features: 1) measurement of body surface position and shape by using an optical tracking system, 2) collision avoidance path generation to automatically approach the robot to body surface, 3) contact force control between the transducer and the body surface, and 4) transducer direction control with keeping of contact force to a target in an intraoperative echogram. To valildate the system feasibility, corectness of body surcace reconstruction, positioning accuracy of the robot without contact, applied force to body surface using contact force control, and positioning accuracy to a target defined on an intraoperative echogram plane with contact force control. From the results, contact force is kept in appropriate range (1–6[N]) to emit ultrasound in the body and positioning accuracy in normal breathing is 0.5 ± 0.27[mm] and 1.6[mm] in the worst. The results demonstrated that the system has a great potential to realize accurate transducer positioning with contact to body surface.