In a minimally invasive percutaneous procedure like biopsy, brachytherapy, and tissue ablation, the inner soft tissue is accessed through surgical needle-puncture of the skin. This process reduces tissue damage and risk of infection and improves patient recovery time. However, its effectiveness depends on the needle’s ability to travel on a curved path, avoid obstacles, and maintain high targeting accuracy. Conventional needles are passive and have limited steerability and trajectory correction capability. This has motivated researchers to develop actuation mechanisms to create active needles. In this study, an innovative active steerable needle with a single shape memory alloy (SMA) wire actuator is designed, fabricated, and tested for maneuver. A closed-loop Proportional Integral Derivative (PID) controller with position feedback is developed to control needle tip deflection in air and tissue-mimicking gels. The needle tip is deflected up to 5.75 mm in the air medium. In tissue-mimicking gel, it is deflected up to 15 mm in a predefined trajectory during a 100 mm insertion depth. Our results show that needle tip deflection control has an average root mean square error (RMSE) of 0.72 mm in the air and 1.26 mm in the tissue-mimicking gel. The trajectory tracking performance of the designed SMA actuated needle and its control system show the effectiveness of the active needle in the percutaneous procedures. Future work includes testing the needle’s performance in the biological tissues.
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Steerable Needle Trajectory Following in the Lung: Torsional Deadband Compensation and Full Pose Estimation With 5DOF Feedback for Needles Passing Through Flexible Endoscopes
Bronchoscopic diagnosis and intervention in the lung is a new frontier for steerable needles, where they have the potential to enable minimally invasive, accurate access to small nodules that cannot be reliably accessed today. However, the curved, flexible bronchoscope requires a much longer needle than prior work has considered, with complex interactions between the needle and bronchoscope channel, introducing new challenges in steerable needle control. In particular, friction between the working channel and needle causes torsional windup along the bronchoscope, the effects of which cannot be directly measured at the tip of thin needles embedded with 5 degree-of-freedom magnetic tracking coils. To compensate for these effects, we propose a new torsional deadband-aware Extended Kalman Filter to estimate the full needle tip pose including the axial angle, which defines its steering direction. We use the Kalman Filter estimates with an established sliding mode controller to steer along desired trajectories in lung tissue. We demonstrate that this simple torsional deadband model is sufficient to account for the complex interactions between the needle and endoscope channel for control purposes. We measure mean final targeting error of 1.36 mm in phantom tissue and 1.84 mm in ex-vivo porcine lung, with mean trajectory following error of 1.28 mm and 1.10 mm, respectively.
more » « less- Award ID(s):
- 1652588
- NSF-PAR ID:
- 10278825
- Date Published:
- Journal Name:
- Proceedings of the ASME 2020 Dynamic Systems and Control Conference
- Page Range / eLocation ID:
- V001T05A003
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Steerable needles are capable of accurately targeting difficult-to-reach clinical sites in the body. By bending around sensitive anatomical structures, steerable needles have the potential to reduce the invasiveness of many medical procedures. However, inserting these needles with curved trajectories increases the risk of tissue damage due to perpendicular forces exerted on the surrounding tissue by the needle’s shaft, potentially resulting in lateral shearing through tissue. Such forces can cause significant tissue damage, negatively affecting patient outcomes. In this work, we derive a tissue and needle force model based on a Cosserat string formulation, which describes the normal forces and frictional forces along the shaft as a function of the planned needle path, friction model and parameters, and tip piercing force. We propose this new force model and associated cost function as a safer and more clinically relevant metric than those currently used in motion planning for steerable needles. We fit and validate our model through physical needle robot experiments in a gel phantom. We use this force model to define a bottleneck cost function for motion planning and evaluate it against the commonly used path-length cost function in hundreds of randomly generated three-dimensional (3D) environments. Plans generated with our force-based cost show a 62% reduction in the peak modeled tissue force with only a 0.07% increase in length on average compared to using the path-length cost in planning. Additionally, we demonstrate planning with our force-based cost function in a lung tumor biopsy scenario from a segmented computed tomography (CT) scan. By directly minimizing the modeled needle-to-tissue force, our method may reduce patient risk and improve medical outcomes from steerable needle interventions.
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Abstract Enhanced understanding of neuropathologies has created a need for more advanced tools. Current neural implants result in extensive glial scarring and are not able to highly localize drug delivery due to their size. Smaller implants reduce surgical trauma and improve spatial resolution, but such a reduction requires improvements in device design to enable accurate and chronic implantation in subcortical structures. Flexible needle steering techniques offer improved control over implant placement, but often require complex closed‐loop control for accurate implantation. This study reports the development of steerable microinvasive neural implants (S‐MINIs) constructed from borosilicate capillaries (OD = 60 µm, ID = 20 µm) that do not require closed‐loop guidance or guide tubes. S‐MINIs reduce glial scarring 3.5‐fold compared to prior implants. Bevel steered needles are utilized for open‐loop targeting of deep‐brain structures. This study demonstrates a sinusoidal relationship between implant bevel angle and the trajectory radius of curvature both in vitro and ex vivo. This relationship allows for bevel‐tipped capillaries to be steered to a target with an average error of 0.23 mm ± 0.19 without closed‐loop control. Polished microcapillaries present a new microinvasive tool for chronic, predictable targeting of pathophysiological structures without the need for closed‐loop feedback and complex imaging.
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Abstract Active needles demonstrate improved accuracy and tip deflection compared to their passive needle counterparts, a crucial advantage in percutaneous procedures. However, the ability of these needles to effectively navigate through tissues is governed by needle-tissue interaction, which depends on the tip shape, the cannula surface geometry, and the needle insertion method. In this research, we evaluated the effect of cannula surface modifications and the application of a vibrational insertion technique on the performance of shape memory alloy (SMA)-actuated active needles. These features were inspired by the mosquito proboscis’ unique design and skin-piercing technique that decreased the needle tissue interaction force, thus enhancing tip deflection and steering accuracy. The bioinspired features, i.e., mosquito-inspired cannula design and vibrational insertion method, in an active needle reduced the insertion force by 26.24% and increased the tip deflection by 37.11% in prostate-mimicking gel. In addition, trajectory tracking error was reduced by 48%, and control effort was reduced by 23.25%, pointing towards improved needle placement accuracy. The research highlights the promising potential of bioinspired SMA-actuated active needles. Better tracking control and increased tip deflection are anticipated, potentially leading to improved patient outcomes and minimized risk of complications during percutaneous procedures.
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Abstract Active needles obtain more significant tip deflection and improved accuracy over passive needles for percutaneous procedures. However, their ability to navigate through tissues to reach targets depends upon the actuation mechanism, the tip shape, and the surface geometry of the shaft. In this study, we investigate the benefits of changing the surface geometry of the active needle shaft in a) needle tip deflection and b) trajectory tracking during tissue insertion. The modifications in passive needle surface geometry have been proven to reduce friction force, tissue displacement, and tissue damage. This study incorporates the effect of modifying the regular smooth cannula with a mosquito proboscis-inspired design in the active needles. The changes in insertion force, tip deflection, and trajectory tracking control during insertion into a prostate-mimicking phantom are measured. Results show that insertion force is reduced by up to 10.67% in passive bevel-tip needles. In active needles, tip deflection increased by 12.91% at 150mm when the cannula is modified. The bioinspired cannula improved trajectory tracking error in the active needle by 39% while utilizing up to 17.65% lower control duty cycle. Improving tip deflection and tracking control would lead to better patient outcomes and reduced risk of complications during percutaneous procedures.
- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1115/DSCC2020-3163
