Rox Margaret, Emerson Maxwell, Ertop Tayfun Efe, Fried Inbar, Fu Mengyu, Hoelscher Janine, Kuntz Alan, Granna Josephine, Mitchell Jason, Lester Michael, Maldonado Fabien, Gillaspie Erin A, Akulian Jason A, Alterovitz Ron, Webster Robert J
Department of Mechanical Engineering and the Vanderbilt Institute for Surgery and Engineering at Vanderbilt University, Nashville, TN 37203, USA.
Department of Computer Science at the University of North Carolina at Chapel Hill, NC 27599, USA.
IEEE Access. 2020;8:181411-181419. doi: 10.1109/access.2020.3028374. Epub 2020 Oct 2.
The maximum curvature of a steerable needle in soft tissue is highly sensitive to needle shaft stiffness, which has motivated use of small diameter needles in the past. However, desired needle payloads constrain minimum shaft diameters, and shearing along the needle shaft can occur at small diameters and high curvatures. We provide a new way to adjust needle shaft stiffness (thereby enhancing maximum curvature, i.e. "steerability") at diameters selected based on needle payload requirements. We propose helical dovetail laser patterning to increase needle steerability without reducing shaft diameter. Experiments in phantoms and ex vivo animal muscle, brain, liver, and inflated lung tissues demonstrate high steerability in soft tissues. These experiments use needle diameters suitable for various clinical scenarios, and which have been previously limited by steering challenges without helical dovetail patterning. We show that steerable needle targeting remains accurate with established controllers and demonstrate interventional payload delivery (brachytherapy seeds and radiofrequency ablation) through the needle. Helical dovetail patterning decouples steerability from diameter in needle design. It enables diameter to be selected based on clinical requirements rather than being carefully tuned to tissue properties. These results pave the way for new sensors and interventional tools to be integrated into high-curvature steerable needles.
在软组织中，可操纵针的最大曲率对针杆刚度高度敏感，这促使过去使用小直径针。然而，所需的针负载限制了最小杆直径，并且在小直径和高曲率下可能会沿着针杆发生剪切。我们提供了一种新方法来调整基于针负载要求选择的直径下的针杆刚度（从而提高最大曲率，即“可操纵性”）。我们提出螺旋燕尾激光图案化，以在不减小杆直径的情况下提高针的可操纵性。在仿体以及离体动物肌肉、大脑、肝脏和充气肺组织中的实验证明了在软组织中的高可操纵性。这些实验使用了适用于各种临床场景的针直径，而这些直径在没有螺旋燕尾图案化的情况下，以前受到转向挑战的限制。我们表明，使用既定的控制器，可操纵针的靶向仍然准确，并展示了通过针进行介入性负载递送（近距离放射治疗种子和射频消融）。螺旋燕尾图案化在针的设计中使可操纵性与直径脱钩。它能够根据临床要求选择直径，而不是根据组织特性进行精细调整。这些结果为将新的传感器和介入工具集成到高曲率可操纵针中铺平了道路。
