Ultrasound (US) calibration is the process of determining the unknown transformation from a coordinate frame such as the robot’s tooltip to the US image frame and is a necessary task for any robotic or tracked US system. US calibration requires submillimeter-range accuracy for most applications, but it is a time-consuming and repetitive task. We provide a new framework for automatic US calibration with robot assistance and without the need for temporal calibration.US calibration based on active echo (AE) phantom was previously proposed, and its superiority over conventional cross-wire phantom-based calibration was shown. In this work, we use AE to guide the robotic arm motion through the process of data collection; we combine the capability of the AE point to localize itself in the frame of the US image with the automatic motion of the robotic arm to provide a framework for calibrating the arm to the US image automatically.
 Aalamifar, Fereshteh, Alexis Cheng, Younsu Kim, Xiao Hu, Haichong K. Zhang, Xiaoyu Guo, and Emad M. Boctor. “Robot-assisted automatic ultrasound calibration.” International journal of computer assisted radiology and surgery (2016): 1-9.