Fig. 12.

Closed-loop needle steering results. Example of failed needle steering: (a) Orthogonal views of successive incremental scans during needle steering in ex vivo tissue, with the output from the steering planner after each scan below. The needle base was inserted 5 mm between each scan, with rotational orientation and duty-cycle setting determined by the steering planner outputs. Error in placing the tip at the target bead was 8.14 mm after the final insertion. The needle failed to reach the target due to interference from internal vessels that could be visualized in the ultrasound images. (b) Section of tissue sample with example vessels and approximate direction of needle insertion indicated.