Robot-Assisted Automatic Ultrasound Calibration Without External Trackers

Robotic ultrasound (US)-guided system improves surgical flexibility and accuracy. US calibration is the key to obtaining spatial relationships and localization of US images. However, existing calibration methods mainly rely on an external tracker, which leads to complicated workflow and is prone to error accumulation. In this article, we proposed a robot-assisted automatic US calibration method. This method can automatically complete the US calibration without any external tracker, thus improving the calibration accuracy and simplifying the workflow. In addition, we propose an automatic image segmentation method incorporating prior knowledge. It automatically segments the features of the calibration model in the US image during the US scanning process and ensures the smooth execution of the automatic robot calibration process. Specifically, we transformed the calibration problem into a point-to-point registration problem and conducted experiments using three different registration algorithms. The results show that the calibration accuracy of our method is $0.65~\pm ~0.20$ mm. Our method significantly reduces calibration time compared to manual calibration. We also compare the proposed method with state-of-the-art methods, and the results demonstrated that the proposed method performs better.