Freehand ultrasound guided robotic needle steering
As postdoc fellow at Stanford University I am working within a National Health Institute (NIH) funded project for the development of a clinically transferable platform for percutaneous ablations of liver tumors.
Percutaneous tumor ablation is one of the least invasive methods for the treatment of liver cancer, but its application is limited by the linear path of straight ablation probes (needles) and the poor targeting accuracy of manual insertion. Robotic steerable needles can be inserted along controlled curved paths. This enables accessing challenging tumor locations and can potentially improve tumor targeting accuracy thanks to the ability to course-correct the needle during insertion. However, barriers to clinical adoption of steerable needles remain. These include low steering perfomances in biological tissue, lack of integrated clinical therapy, and the need for a practical method to localize curved needles using freehand 2D ultrasound imaging.
To improve the steering performances in biological tissue (liver tissue), we use the so called “exaggerated asymmetric tip” needle steering principle. In particular, our needle design features a flexure joint which allows having full control of the tip asymmetry and therefore of the curvature in biological tissue upon needle insertion. This allows increasing the steering performance without compromising its safety and control reliability, since the tip articulation is released during any needle base rotation from the base, or needle spinning. The needle spinning is necessary to steer the needle in 3D. The tip design also enables therapy delivery at the target site. In this work the needle shaft is insulated and used for conveying radio frequency current to the tip. In a real scenario, the needle tip will be firstly placed at the tumor location, and then the radio frequency ablation will be initiated in order to destroy (by heat) the surrounding cancer tissue.
The control of the robotic steerable needle in liver tissue is based on feedback from freehand 2D ultrasound imaging. Ultrasound is the most ubiquitous and safest (no harmful radiations) imaging system for percutaneus interventions. Technology challenges are related to the real time and automatic needle segmentation and the 2D nature of ultrasound imaging (the needle moves on trajectories in 3D). We implemented a human-in-the-loop control strategy and a customized estimation algorithm that allows using a coarse needle localization from expert ultrasound users (interventional radiologists).
I am currently performing in-vivo liver experimentation to assess the targeting accuracy of the needle steering platform control.
This work has not been published yet, but a brief overview is presented in .
 Gerboni, G., Greer, J. D., Laeseke, P. F., Hwang, G. L., Okamura, A. M. (2017). Highly Articulated Robotic Needle Achieves Distributed Ablation of Liver Tissue. IEEE Robotics and Automation Letters.
 Gerboni, G., A. Diodato, Greer, J. D., Laeseke, P. F., Hwang, G. L., Okamura, A. M. IEEERSJ IROS2018 International Conference on Intelligent Robots. Workshop on Soft and Continuous robots for surgery. Madrid, October 1-5, 2018. Robotic needle steering platform enabling effective clinical tests.