Safety and feasibility of robotic probe steering in echocardiography

Abstract Introduction Work related injury is common in medical sonographers. A robotic arm designed to assist in a (transthoracic echocardiography) TTE might be a useful alternative to alleviate the muscle strain of sonographers. Purpose In this study the feasibility and safety of a robotic device intended to improve the ergonomics of TTE is tested. Methods A CE marked robotic device (LBR iiwa 7 R800, KUKA) mounted with a transthoracic echoprobe and an echo calibration phantom (UltraiQ General Purpose fantoom, Cablon medical) were used to assess the feasibility of robotic assistance. A predefined protocol was used to acquire images of the phantom in 6 standardized viewpoints of the robotically controlled echo probe with respect to the phantom. The probe was moved from a predefined standardized starting point to the first viewpoint, perpendicular to the surface of the phantom. The probe was subsequently rotated 20° and -20° along both its long and short axis, and 90° around its central axis to reach the other 5 viewpoints. Time to and maximum contact force during acquisition was measured. The maximum contact force used during a manual standard TTE acquisition was also measured using the same force sensor. All measurements were performed 3 times. Results The average time to reach the 1st viewpoint perpendicular to the surface of the phantom from above the phantom was 4.6s, the maximum contact force was 10.1N. The time used for rotation on the short axis of the probe was 4.1 s, with a maximum force of 11.8N. The time it took to rotate the probe 20° and -20° around its long axis to reach viewpoints 4 and 5 was 4.5s with a maximum force of 9.48N. The average time to rotate the probe 90° around its axis and reach the 6th viewpoint was 5.0 s, the maximum contact force at the rotated axis was 10.3N. The maximum contact force was 11.8N throughout all movements. The reference maximum contact force by manual TTE assessment on a human was 11.5N. The contact forces of the probe controlled by a robot on the phantom did not exceed the predefined maximum force throughout standardized movements used during a TTE assessment. Conclusion Robotically assisted TTE scanning was safe in terms of the applied force throughout image acquisition in all viewpoints and comparable with forces used during manual TTE. Imaging at target viewpoints used in a regular TTE assessment was feasible as all images were acquired within a reasonable timeframe. Further studies are needed to evaluate its effectiveness in transthoracic echocardiography in volunteers and patients.