263 research outputs found

    Development of A Kinetic Model For Loop-Free Colonoscopy Technology

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    The colonoscope is an important tool in diagnosis and management of diseases of the colon. One of the ongoing challenges with this device is that the colonoscope may form a loop together with the colon during the procedure. The result of the loop is that further insertion of the scope in the colon may not be possible. The loop may also cause risks of perforation of the colon and pain in the patient. There are currently several existing devices to overcome loop formation in colonoscopy, some of which have been introduced in clinical work. However, empirical assessment shows that these devices do not work very well. This is the motivation for the research presented in this thesis. In this thesis, a new paradigm of thinking, “doctor-assisted colonoscopy,” is proposed to overcome loop formation. In this new approach, the physician’s role is enhanced with new information that is acquired by sensors outside the human body and inferred from the mathematical model. It is referred to as a kinetic model due to the fact that this model describes the kinetic behaviour of the scope. This thesis is devoted to development of this kinetic model. In this study, the model of the colonoscope and the model of the colon are developed based on the Timoshenko beam theory, and parameters in both models are determined by the experiments. The following conclusions then are made: (1) self-locking of the colonoscope is the most basic cause for a loop to occur, while structural instability of the colonsocope is dependent on the self-locking; (2) both the scope and the colon can be well represented with the Timoshenko beam elements and the Linear Complementary Problem (LCP) formulation derived from Signorini’s law, and Coulom’s law for representation of interactions between the colon and scope is adequate; (3) there are effects from the location, looping, and tip deflection of the scope on flexural rigidity of the scope. Approximately, the flexural rigidity of the CF-Q160L colonoscope ranges from 300 to 650 N‱cm2, and its accuracy is proven by a good agreement between the model predicted result and experimental result; (4) Rayleigh damping for the CF-Q160L colonoscope depends more on the mass matrix [M] of the colonoscope than the stiffness matrix [K], which is evident by the large coefficient value of “alpha” (0.3864) and the small coefficient value of “beta” (0.0164). The contributions of this thesis are: (1) the finding that the main cause of the loop is not structural instability of the colonoscope but rather self-locking of the colonoscope, which could lead to design of a “new-generation” colonoscope to avoid the loop; (2) a systematic evaluation of the existing colonoscopy technologies based on the well-proven Axiomatic Design Theory (ADT), which will serve as a guideline for the development of future new colonoscopes in future; (3) an approach to developing a kinetic model of the colonoscope useful to modeling similar objects such as a catheter guide-wire; (4) a novel ex-vivo colonoscopy test-bed with the kinetic and kinematic measurements useful for validation of new designs in colonoscopy technology and also useful for training physicians who perform the colonoscopy procedure; and (5) a new paradigm of thinking for colonoscopy called “doctor-assisted colonoscopy,” which has potential applications to other medical procedures such as catheter-based procedures

    Surgical Subtask Automation for Intraluminal Procedures using Deep Reinforcement Learning

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    Intraluminal procedures have opened up a new sub-field of minimally invasive surgery that use flexible instruments to navigate through complex luminal structures of the body, resulting in reduced invasiveness and improved patient benefits. One of the major challenges in this field is the accurate and precise control of the instrument inside the human body. Robotics has emerged as a promising solution to this problem. However, to achieve successful robotic intraluminal interventions, the control of the instrument needs to be automated to a large extent. The thesis first examines the state-of-the-art in intraluminal surgical robotics and identifies the key challenges in this field, which include the need for safe and effective tool manipulation, and the ability to adapt to unexpected changes in the luminal environment. To address these challenges, the thesis proposes several levels of autonomy that enable the robotic system to perform individual subtasks autonomously, while still allowing the surgeon to retain overall control of the procedure. The approach facilitates the development of specialized algorithms such as Deep Reinforcement Learning (DRL) for subtasks like navigation and tissue manipulation to produce robust surgical gestures. Additionally, the thesis proposes a safety framework that provides formal guarantees to prevent risky actions. The presented approaches are evaluated through a series of experiments using simulation and robotic platforms. The experiments demonstrate that subtask automation can improve the accuracy and efficiency of tool positioning and tissue manipulation, while also reducing the cognitive load on the surgeon. The results of this research have the potential to improve the reliability and safety of intraluminal surgical interventions, ultimately leading to better outcomes for patients and surgeons

    Nonholonomic Closed-loop Velocity Control of a Soft-tethered Magnetic Capsule Endoscope

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    In this paper, we demonstrate velocity-level closedloop control of a tethered magnetic capsule endoscope that is actuated via serial manipulator with a permanent magnet at its end-effector. Closed-loop control (2 degrees-of-freedom in position, and 2 in orientation) is made possible with the use of a real-time magnetic localization algorithm that utilizes the actuating magnetic field and thus does not require additional hardware. Velocity control is implemented to create smooth motion that is clinically necessary for colorectal cancer diagnostics. Our control algorithm generates a spline that passes through a set of input points that roughly defines the shape of the desired trajectory. The velocity controller acts in the tangential direction to the path, while a secondary position controller enforces a nonholonomic constraint on capsule motion. A soft nonholonomic constraint is naturally imposed by the lumen while we enforce a strict constraint for both more accurate estimation of tether disturbance and hypothesized intuitiveness for a clinician’s teleoperation. An integrating disturbance force estimation control term is introduced to predict the disturbance of the tether. This paper presents the theoretical formulations and experimental validation of our methodology. Results show the system’s ability to achieve a repeatable velocity step response with low steady-state error as well as ability of the tethered capsule to maneuver around a bend

    A Biomimetic steering robot for Minimally invasive surgery application

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    International audienceMinimally Invasive Surgery represents the future of many types of medical inter- ventions such as keyhole neurosurgey or transluminal endoscopic surgery. These procedures involve insertion of surgical instruments such as needles and endoscopes into human body through small incision/ body cavity for biopsy and drug delivery. However, nearly all surgical instruments for these procedures are inserted manually and there is a long learning curve for surgeons to use them properly. Many research efforts have been made to design active instruments (endoscope, needles) to improve this procedure during last decades. New robot mechanisms have been designed and used to improve the dexterity of current endoscope. Usually these robots are flexible and can pass the constrained space for fine manipulations. In recent years, a con- tinuum robotic mechanism has been investigated and designed for medical surgery. Those robots are characterized by the fact that their mechanical components do not have rigid links and discrete joints in contrast with traditional robot manipula- tors. The design of these robots is inspired by movements of natural animals such as tongues, elephant trunks and tentacles. The unusual compliance and redundant degrees of freedom of these robots provide strong potential to achieve delicate tasks successfully even in cluttered and unstructured environments. This chapter will present a complete application of a continuum robot for Mini- mally Invasive Surgery of colonoscopy. This system is composed of a micro-robotic tip, a set of position sensors and a real-time control system for guiding the explo- ration of colon. Details will be described on the modeling of the used pneumatic actuators, the design of the mechanical component, the kinematic model analysis and the control strategy for automatically guiding the progression of the device inside the human colon. Experimental results will be presented to check the perfor- mances of the whole system within a transparent tube

    A. Training Simulators for Gastrointestinal Endoscopy: Current and Future Perspectives

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    Over the last decades, visual endoscopy has become a gold standard for the detection and treatment of gastrointestinal cancers. However, mastering endoscopic procedures is complex and requires long hours of practice. In this context, simulation-based training represents a valuable opportunity for acquiring technical and cognitive skills, suiting the different trainees’ learning pace and limiting the risks for the patients. In this regard, the present contribution aims to present a critical and comprehensive review of the current technology for gastrointestinal (GI) endoscopy training, including both commercial products and platforms at a research stage. Not limited to it, the recent revolution played by the technological advancements in the fields of robotics, artificial intelligence, virtual/augmented reality, and computational tools on simulation-based learning is documented and discussed. Finally, considerations on the future trend of this application field are drawn, highlighting the impact of the most recent pandemic and the current demographic trends

    Image-Based Flexible Endoscope Steering

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    Manually steering the tip of a flexible endoscope to navigate through an endoluminal path relies on the physician’s dexterity and experience. In this paper we present the realization of a robotic flexible endoscope steering system that uses the endoscopic images to control the tip orientation towards the direction of the lumen. Two image-based control algorithms are investigated, one is based on the optical flow and the other is based on the image intensity. Both are evaluated using simulations in which the endoscope was steered through the lumen. The RMS distance to the lumen center was less than 25% of the lumen width. An experimental setup was built using a standard flexible endoscope, and the image-based control algorithms were used to actuate the wheels of the endoscope for tip steering. Experiments were conducted in an anatomical model to simulate gastroscopy. The image intensity- based algorithm was capable of steering the endoscope tip through an endoluminal path from the mouth to the duodenum accurately. Compared to manual control, the robotically steered endoscope performed 68% better in terms of keeping the lumen centered in the image

    Preliminary development of the Active Colonoscopy Training Model

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    Closed Loop Control of a Tethered Magnetic Capsule Endoscope

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    Magnetic field gradients have repeatedly been shown to be the most feasible mechanism for gastrointestinal capsule endoscope actuation. An inverse quartic magnetic force variation with distance results in large force gradients induced by small movements of a driving magnet; this necessitates robotic actuation of magnets to implement stable control of the device. A typical system consists of a serial robot with a permanent magnet at its end effector that actuates a capsule with an embedded permanent magnet. We present a tethered capsule system where a capsule with an embedded magnet is closed loop controlled in 2 degree-of-freedom in position and 2 degree-offreedom in orientation. Capitalizing on the magnetic field of the external driving permanent magnet, the capsule is localized in 6- D allowing for both position and orientation feedback to be used in a control scheme. We developed a relationship between the serial robot’s joint parameters and the magnetic force and torque that is exerted onto the capsule. Our methodology was validated both in a dynamic simulation environment where a custom plug-in for magnetic interaction was written, as well as on an experimental platform. The tethered capsule was demonstrated to follow desired trajectories in both position and orientation with accuracy that is acceptable for colonoscopy

    Photometric single-view dense 3D reconstruction in endoscopy

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    Visual SLAM inside the human body will open the way to computer-assisted navigation in endoscopy. However, due to space limitations, medical endoscopes only provide monocular images, leading to systems lacking true scale. In this paper, we exploit the controlled lighting in colonoscopy to achieve the first in-vivo 3D reconstruction of the human colon using photometric stereo on a calibrated monocular endoscope. Our method works in a real medical environment, providing both a suitable in-place calibration procedure and a depth estimation technique adapted to the colon's tubular geometry. We validate our method on simulated colonoscopies, obtaining a mean error of 7% on depth estimation, which is below 3 mm on average. Our qualitative results on the EndoMapper dataset show that the method is able to correctly estimate the colon shape in real human colonoscopies, paving the ground for truescale monocular SLAM in endoscopy
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