Needle Tip Pose Estimation for Ultrasound-Guided Steerable Flexible Needle With a Complicated Trajectory in Soft Tissue

Visualization of the surgical needle is critical for an image guided insertion. However, it is difficult to obtain a 3D tip pose of a steerable flexible needle under 2D US images. In this letter, an image processing method is used to extract the needle shaft radial cross-sectional centroid coordinates (NSRCCCs). Based on the NSRCCCs, two methods are proposed to estimate the needle tip pose in real-time, which are based on Rodrigues’ rotation formula, and Fourier expansion with three-terms and linear interpolation algorithm (FEWT&LIA), respectively. In order to validate the methods proposed in this letter, the insertion experiments with different depths are conducted in phantom tissues, and the results show that the mean errors are 0.68 mm and 0.65 mm with using the Rodrigues’ rotation formula based method and the FEWT&LIA based method, respectively, showing clinically acceptable accuracy.