搜索结果：... International Symposium on Medical Robotics. International Symposium on Medical Robotics

Automated laser surgery with sensor fusion is an important problem in medical robotics since it requires precise control of mirrors used to steer the laser systems. The propagation of the laser beam should satisfy the geometric constraints of the surgical site but the relation between the number of mirrors and the design of the optical path remains an unsolved problem. Furthermore, different types of surgery (e.g. endoscopic vs open surgery) can require different optical designs with varying number of mirrors to successfully steer the laser beam to the tissue. A generalized method for controlling the laser beam in such systems remains an open research question. This paper proposes an analytical model for a laser-based surgical system with an arbitrary number of mirrors, which is referred as an "N-mirror" robotic system. This system consists of three laser inputs to transmit the laser beam to the tissue surface through N number of mirrors, which can achieve surface scanning, tissue resection and tissue classification separately. For sensor information alignment, the forward and inverse kinematics of the N-mirror robot system are derived and used to calculate the mirror angles for laser steering at the target surface. We propose a system calibration method to determine the laser input configuration that is required in the kinematic modelling. We conduct simulation experiments for a simulated 3-mirror system of an actual robotic laser platform and a 6-mirror simulated robot, both with 3-laser inputs. The simulation experiments for system calibration show results of maximum position offset smaller than 0.127 mm and maximum angle offset smaller than 0.05° for the optimal laser input predictions.

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.

Lumbar epidural injection requires precise needle placement to ensure efficient drug delivery into the epidural space. MRI-compatible robotic systems offer unique advantages for this procedure by combining the advantages of intraoperative MRI guidance with the precision and dexterity of robotic assistance. This paper presents a 4-degree-of-freedom (DOF) MRI-compatible robotic system designed to assist surgeons in performing lumbar injections with improved accuracy and consistency. The proposed system features a modular architecture comprising an actuation unit, a two-layer linkage mechanism, and a needle placer. The kinematics of the system were derived, and a control framework incorporating backlash compensation was implemented. A workspace analysis was conducted, with the effective workspace found to be ±72.9 mm (medial-lateral) and ±32.5 mm (superior-inferior), and a tilting range exceeding 25°. As a proof of concept, the prototype was experimentally evaluated to validate its mechanical performance. The results demonstrated sub-millimeter precision with an average deviation from a mean location of 0.33 mm, confirming the feasibility of accurate and repeatable needle guidance, and marking a step toward clinical translation of robot-assisted MRI-guided lumbar injection procedures.

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.

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.

Retinal surgery can be performed only by surgeons possessing advanced surgical skills because of the small, confined intraocular space, and the restricted free motion of instruments in contact with the sclera. Snake-like robots could be essential for use in retinal surgery to overcome this problem. Such robots can approach from suitable directions and operate delicate tissues when performing retinal vein cannulation, epiretinal membrane peeling and so on. In this study, we propose an improved integrated robotic intraocular snake (I2RIS), which is a new version of our previous IRIS. This update focuses on the dexterous distal unit design and the drive unit design. The proposed dexterous distal unit consists of small elements with reduced contact stress. The proposed drive unit includes a new wire drive mechanism where the drive pulley is mounted at a right angle relative to the actuation direction (also, relative to the conventional direction). A geometric analysis and mechanical design show that the proposed drive mechanism is simpler and easier to assemble and yields higher accuracy than the conventional drive mechanism. Furthermore, considering clinical use, the instrument of the I2RIS is detachable from the motor unit for cleaning, sterilization, and attachment of various surgical tools. Weighing merely 31.3 g, the proposed mechanism is only one third of the weight of the conventional IRIS. The basic functions and effectiveness of the proposed mechanism are verified by experiments on 5:1 scaled-up models of the dexterous distal unit and actual-size models of the instrument and motor units.

Surgeon hand tremor limits human capability during microsurgical procedures such as those that treat the eye. In contrast, elimination of hand tremor through the introduction of microsurgical robots diminishes the surgeons tactile perception of useful and familiar tool-to-sclera forces. While the large mass and inertia of eye surgical robot prevents surgeon microtremor, loss of perception of small scleral forces may put the sclera at risk of injury. In this paper, we have applied and compared two different methods to assure the safety of sclera tissue during robot-assisted eye surgery. In the active control method, an adaptive force control strategy is implemented on the Steady-Hand Eye Robot in order to control the magnitude of scleral forces when they exceed safe boundaries. This autonomous force compensation is then compared to a passive force control method in which the surgeon performs manual adjustments in response to the provided audio feedback proportional to the magnitude of sclera force. A pilot study with three users indicate that the active control method is potentially more efficient.

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.

Vitrectomy is that portion of retinal surgery in which the vitreous gel is removed either as a definitive treatment or to provide direct tool access to the retina. This procedure should be conducted prior to several eye surgeries in order to provide better access to the eyeball posterior. It is a relatively repeatable and straight forward procedure that lends itself to robotic assistance or potentially autonomous performance if tool contact with critical structures can be avoided. One of the detrimental incidences that can occur during the robot-assisted vitrectomy is when the robot penetrates the tool more than allowed boundaries into the eyeball toward retina. In this paper, we provide filtering and control to guide instrument insertion depth in order to avoid tool-to-retina contact. For this purpose, first the tool insertion depth measurement is improved using a Kalman filtering (KF) algorithm. This improved measurement is then used in an adaptive control strategy by which the robot reduces the tool insertion depth based on a predefined and safe trajectory for it, when safe boundaries are overstepped. The performance of the insertion depth safety control system is then compared to one in which the insertion depth is not passed through a Kalman filter prior to being fed to the control system. Our results indicate that applying KF in the adaptive control of the robot enhances procedure safety and enables the robot to always keep the tool insertion depth under the safe levels.

Bevel-tip needles are commonly utilized in percutaneous medical interventions where a curved insertion trajectory is required. To avoid deviation from the intended trajectory, needle shape sensing and tip localization is crucial in providing the operator with feedback. There is an abundance of previous work that investigate the medical application of fiber Bragg grating (FBG) sensors, but most works select only one specific type of fiber among the many available sensor options to integrate into their hardware designs. In this work, we compare two different types of FBG sensors under identical conditions and application, namely, acting as the sensor for needle insertion shape reconstruction. We built a three-channel single core needle and a seven-channel multicore fiber (MCF) needle and discuss the pros and cons of both constructions for shape sensing experiments into constant curvature jigs. The overall needle tip error is 1.23 mm for the single core needle and 2.08 mm for the multicore needle.

In this paper we introduce a remotely actuated MRI-compatible needle driving device for pain injections in the lower back. This device is able to manipulate the needle inside the closed-bore MRI scanner under the control of the interventional radiologist inside both the scanner room and the console room. The device consists of a 2 degrees of freedom (DOF) needle driver and an actuation box. The 2-DOF needle driver is placed inside the scanner bore and driven by the actuation box settled at the end of the table through a beaded chain transmission. This novel remote actuation design could reduce the weight and profile of the needle driver that is mounted on the patient, as well as minimize the potential imaging noise introduced by the actuation electronics. The actuation box is designed to perform needle intervention in both manual and motorized fashion by utilizing a mode switch mechanism. A mechanical hard stop is also incorporated to improve the device's safety. The bench-top accuracy evaluation of the device demonstrated a small mean needle placement error (< 1 mm) in a phantom study.

Mechanics-based models have been developed to describe the shape of tendon-actuated continuum robots. Models have also been developed to describe the shape of concentric tube robots, i.e., nested combinations of precurved superelastic tubes. While an important class of continuum robots used in endoscopic and intracardiac medical applications combines these two designs, existing models do not cover this combination. Tendon-actuated models are limited to a single tube while concentric tube models do not include tendon-produced forces and moments. This paper derives a mechanics-based model for this hybrid design and assesses it using numerical and physical experiments involving a pair of tendon-actuated tubes. It is demonstrated that, similar to concentric tube robots, relative twisting between the tendon-actuated tubes is an important factor in determining overall robot shape.

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.

While the use of tissue-mimicking (TM) phantoms has been ubiquitous in surgical robotics, the translation of technology from laboratory experiments to equivalent intraoperative tissue conditions has been a challenge. The increasing use of lasers for surgical tumor resection has introduced the need to develop a modular, low-cost, functionally relevant TM phantom to model the complex laser-tissue interaction. In this paper, a TM phantom with mechanically and thermally similar properties as human brain tissue suited for photoablation studies and subsequent visualization is developed. The proposed study demonstrates the tuned phantom response to laser ablation for fixed laser power, time, and angle. Additionally, the ablated crater profile is visualized using optical coherence tomography (OCT), enabling high-resolution surface profile generation.

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.

The dominant visual servoing approaches in Minimally Invasive Surgery (MIS) follow single points or adapt the endoscope's field of view based on the surgical tools' distance. These methods rely on point positions with respect to the camera frame to infer a control policy. Deviating from the dominant methods, we formulate a robotic controller that allows for image-based visual servoing that requires neither explicit tool and camera positions nor any explicit image depth information. The proposed method relies on homography-based image registration, which changes the automation paradigm from point-centric towards surgical-scene-centric approach. It simultaneously respects a programmable Remote Center of Motion (RCM). Our approach allows a surgeon to build a graph of desired views, from which, once built, views can be manually selected and automatically servoed to irrespective of robot-patient frame transformation changes. We evaluate our method on an abdominal phantom and provide an open source ROS Moveit integration for use with any serial manipulator. A video is provided.

Vitreoretinal surgery requires dexterity and force sensitivity from the clinician. A system to cooperatively control an integrated surgical robot for high dexterity manipulation within the eye's vitreous space was developed and validated in simulation. The system is composed of a 2 degrees of freedom (DoF) snake-like continuum manipulator that is attached to the end-effector of a 5-DoF rigid robot arm. It is capable of receiving position and orientation commands from a 5-DoF input device in real-time, as well as following pre-planned trajectories. The manipulator is moved to each target pose in real-time, using an optimization method to calculate the inverse kinematics solution. Constraints on the position and orientation ensure the target pose does not harm the patient within the vitreous space, enabling the robot to safely assist the clinician with vitreoretinal surgery when operating in real-time. The simulation demonstrates the system's feasibility and benefits over the existing non-dexterous system.

Retinal vein cannulation (RVC) is a potential treatment for retinal vein occlusion (RVO). Manual surgery has limitations in RVC due to extremely small vessels and instruments involved, as well as the presence of physiological hand tremor. Robot-assisted retinal surgery may be a better approach to smooth and accurate instrument manipulation during this procedure. Motion of the retina and cornea related to heartbeat may be associated with unexpected forces between the tool and eyeball. In this paper, we propose a force-based control strategy to automatically compensate for the movement of the retina maintaining the tip force and sclera force in a predetermined small range. A dual force-sensing tool is used to monitor the tip force, sclera force and tool insertion depth, which will be used to derive a desired joint velocity for the robot via a modified admittance controller. Then the tool is manipulated to compensate for the movement of the retina as well as reduce the tip force and sclera force. Quantitative experiments are conducted to verify the efficacy of the control strategy and a user study is also conducted by a retinal surgeon to demonstrate the advantages of our automatic compensation approach.

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.