... International Symposium on Medical Robotics. International Symposium on Medical Robotics最新文献

This paper presents a flexible needle guidance system and its workflow that enables registration of computed tomography (CT) and electromagnetic (EM) tracking systems with a finite element (FE) simulator for needle-based percutaneous spinal injections. CT is used only pre- and postoperatively for surgical planning and confirmation, while EM tracking is combined intraoperatively with an FE-based needle controller to track the planned needle trajectory and avoid obstacles. Evaluation of the proposed system using a multi-layer soft tissue phantom shows an average targeting accuracy of 0.4mm.

Optical coherence tomography (OCT) is an indispensable imaging modality for the diagnosis and management of many common eye diseases. We previously presented a fixed-base robotic OCT system to enable automated imaging and alleviate the necessity for restricted patient posture required by traditional clinical OCT. To adapt our system to diverse clinic environments, we introduce a mobile robotic OCT system designed for imaging patients in diverse clinical configurations. Our system includes a robot arm, a vertical motorized lift, and a wheeled cart housing essential components for the entire system, and is equipped with real-time motion planning algorithms for head movement tracking and obstacle avoidance during imaging sessions. We validate the system's workspace through robot kinematics and clinical simulation, evaluate dynamic tracking accuracy in real world experiments, and demonstrate obstacle avoidance capability in both simulation and real world. These features will allow us to perform OCT imaging in real clinical settings in the near future.

Exudative (wet) age-related macular degeneration (AMD) is a leading cause of vision loss in older adults, typically treated with intravitreal injections. Emerging therapies, such as subretinal injections of stem cells, gene therapy, small molecules and RPE cells require precise delivery to avoid damaging delicate retinal structures. Robotic systems can potentially offer the necessary precision for these procedures. This paper presents a novel approach for motion compensation in robotic subretinal injections, utilizing real time Optical Coherence Tomography (OCT). The proposed method leverages B⁵-scans, a rapid acquisition of small-volume OCT data, for dynamic tracking of retinal motion along the Z-axis, compensating for physiological movements such as breathing and heartbeat. Validation experiments on ex vivo porcine eyes revealed challenges in maintaining a consistent tool-to-retina distance, with deviations of up to 200 μm for 100 μm amplitude motions and over 80 μm for 25 μm amplitude motions over one minute. Subretinal injections faced additional difficulties, with phase shifts causing the needle to move off-target and inject into the vitreous. These results highlight the need for improved motion prediction and horizontal stability to enhance the accuracy and safety of robotic subretinal procedures.

Vertebral compression fractures are estimated to affect over 200 million people globally. Percutaneous vertebroplasty is a widely accepted minimally invasive treatment, but it has limitations including prolonged radiation exposure for providers and a steep learning curve. To address these challenges, we present two cannula-mounted robot designs for semi-autonomous, high-precision cannula insertion. Both designs are based on an inchworm mechanism, with one using an amplified piezoelectric actuator and the other using a linear actuator inspired approach. Each design is designed to generate at least 150 N of thrust force with submillimeter accuracy to reliably insert the cannula into the vertebral body. Finite element analysis shows that the material deformations of the baseplates, 42 ± 12 μm for the piezo inchworm design and 7.7±3.2 μm for the screw inchworm design, are substantially lower than the corresponding stroke lengths, confirming the feasibility of generating linear motion. An in silico imaging trial reveals the screw inchworm design's 44.4% smaller surgical footprint enables superior cannula insertion trajectory visualization compared to the piezo inchworm design. These results indicate that while both designs meet clinical design requirements for cannula insertion, the screw inchworm robot is better suited for a semi-autonomous approach to vertebroplasty.

In this paper, we evaluate the performance of our controller for flexible needle manipulation for percutaneous interventions in a finite element (FE) simulator. We investigate the use of electromagnetic (EM) tracking as needle tip pose feedback, and how artificial sensor noises can affect tracking performance of the controller. In our simulated study, the control system shows high targeting accuracy and robustness with an overall tip position error of 0.49mm. The addition of needle tip orientation feedback further improves the targeting accuracy for deeper targets, with average error of 0.81mm when only using position feedback, and 0.55mm when using additional orientation feedback.

Retinal microsurgery is a high-precision surgery performed on a delicate tissue requiring the skill of highly trained surgeons. Given the restricted range of instrument motion in the confined intraocular space, snake-like robots may prove to be a promising technology to provide surgeons with greater flexibility, dexterity, and positioning accuracy during retinal procedures such as retinal vein cannulation and epiretinal membrane peeling. Kinematics modeling of these robots is an essential step toward accurate position control. Unlike conventional manipulators, modeling these robots does not follow a straightforward method due to their complex mechanical structure and actuation mechanisms. The hysteresis problem can especially impact the positioning accuracy significantly in wire-driven snake-like robots. In this paper, we propose a data-driven kinematics model using a probabilistic Gaussian mixture model (GMM) and Gaussian mixture regression (GMR) approach with a hysteresis compensation algorithm. Experimental results on the two-degree-of-freedom (DOF) integrated robotic intraocular snake (I²RIS) show that the proposed model with the hysteresis compensation can predict the snake tip bending angle for pitch and yaw with 0.45° and 0.39° root mean square error (RMSE), respectively. This results in overall 60% and 70% improvements of accuracy for yaw and pitch over the same model without the hysteresis compensation.

In this paper, we present a robotically steerable laser ablation probe with application to interstitial thermal therapy. Existing laser interstitial thermal therapy (LITT) methods utilize a straight probe to deliver laser energy around the tip or to the side of the tip. These methods are inadequate to provide effective treatment for large, irregularly shaped tumors. Our robotic probe can be manipulated inside soft tissue to perform ablation at multiple locations, thus enabling conformable ablation for large and complicated tumors. Instead of directly firing laser into soft tissue, a Polydimethylsiloxane (PDMS)/Carbon nanoparticles (CNPs) mixture hosts a multi-mode optical fiber at the probe tip to work as a heater when laser is activated to improve the procedural safety. This paper presents the design and fabrication of the robotic ablation probe, simulation of laser thermal transformation using finite element analysis, and experimental studies that characterize the robot motion and heating effects and demonstrate in vitro ablation.

Left atrial appendage occlusion is a procedure to reduce the risk of thromboembolism in atrial fibrillation patients by blocking the left atrial appendage ostium using an occlusion device implanted by an intra-vascular delivery catheter. The preprocedural planning of the left atrial appendage occlusion procedure aims to identify an optimal implantation trajectory for a successful occlusion implant delivery from a structural understanding of the left atrial appendage. In this paper, a Bayesian Optimization based preprocedural planning approach is proposed for the robotic left atrial appendage occlusion procedure. The preprocedural planner efficiently samples transseptal puncture positions over the fossa ovalis and sequentially optimizes the transseptal puncture location. The iterative linear-quadratic-regulator is employed by the Bayesian Optimization planner for locally optimizing the occlusion trajectory for a given transseptal puncture location. The performance of the proposed Bayesian Optimization based preprocedural planner is evaluated in a simulation environment using a real cardiac anatomy model.

Optical coherence tomography (OCT) is a preferred imaging technology in ophthalmology for diagnosis and management of eye disease. Standard-of-care clinical OCT systems require patients to sit upright, brace their head against the instrument, and fix their gaze into its sensing aperture. These limitations exclude those with involuntary head and eye movements, such as those present in Parkinson's disease and nystagmus, respectively, from undergoing OCT imaging. To overcome these restrictions, we combine our robotic OCT paradigm, which allows flexible patient positioning during imaging, with active cancellation of periodic motion to reduce image artifact during acquisition. We accomplish this by measuring eye motion with on-board pupil cameras, fitting the movement profile in real-time, and augmenting OCT scan waveforms using the predicted eye position. We evaluate this predictive imaging scheme with eye phantoms to precisely simulate motions typical of head and eye movement disorders and compare it to real-time scan aiming. Using registration shift in captured OCT images to quantify residual motion artifact, we demonstrate motion reduction by up to 98.5 % for typical nystagmus frequencies and an average 3.4 × reduction in residual motion compared to scan aiming alone. This approach may provide access to accurate OCT imaging for those with involuntary eye and head movement.

The performance of concentric push-pull robots passing through endoscopes is best if their laser-cut transmission tubes exhibit high axial stiffness, high torsional stiffness, and low bending stiffness. In this paper we simultaneously consider all three output stiffness values in the design problem, explicitly considering axial stiffness, whereas prior work has focused on the bending/torsional stiffness ratio. We show that it is very challenging for existing laser-cut patterns to simultaneously achieve high axial stiffness and low bending stiffness because these stiffnesses are tightly coupled. To break this coupling and balance all three stiffness factors independently, we propose a new laser material removal design approach that leverages local stiffness asymmetry $\left(E{I}_x\ne E{I}_y\right)$ in discrete bending segments separated by segments of solid tube. These discrete asymmetric segments are then rifled down the tube to achieve global stiffness symmetry. We parameterize the design and provide a study of the properties through finite-element analysis. We also consider the effect of interference between the tubes when the discrete segments are not aligned. Results show that our discrete asymmetric segment concept can achieve high axial stiffness and torsional stiffness better than previously suggested laser patterns while maintaining equally low bending stiffness.