Motion Estimation and Reconstruction of a Heart Surface by Means of 2D-/3D-Membrane Models

In order to assist surgeons during minimally invasive interventions on the beating heart, it would be helpful to develop a robotic surgery system, which synchronizes the instruments with the heart surface, so that their positions do not change relative to the point of interest (POI). The synchronization of the robotic manipulators requires an estimation of the heart surface motion. In this paper, a modelbased motion estimation of the heart surface is presented. The motion of a partition of the heart surface is modelled by means of a thin or thick vibrating membrane in order to represent the epicardial surface or the connected epicard and myocard. The membrane motion is described by means of a system of coupled linear partial differential equations (PDEs), whose 3D-input function is assumed to be known. After spatial discretization of the PDE solution space by the Finite Spectral Element Method, a bank of lumped systems is obtained. A Kalman filter is used to estimate the state of the lumped systems by incorporating noisy measurements of the heart surface. Measurements can be the position or velocity of sonomicrometry-based sensors or of certain landmarks, which are tracked by optical sensors. With the model-based estimation it is possible to reconstruct the entire partition of the heart surface even at non-measurement points and thus at each POI

Gaze-contingent Soft Tissue Deformation Tracking for Minimally Invasive Robotic Surgery

The introduction of surgical robots in Minimally Invasive Surgery (MIS) has allowed enhanced manual dexterity through the use of microprocessor controlled mechanical wrists. Although fully autonomous robots are attractive, both ethical and legal barriers can prohibit their practical use in surgery. The purpose of this paper is to demonstrate that it is possible to use real-time binocular eye tracking for empowering robots with human vision by using knowledge acquired in situ. By utilizing the close relationship between the horizontal disparity and the depth perception varying with the viewing distance, it is possible to use ocular vergence for recovering 3D motion and deformation of the soft tissue during MIS procedures. Both phantom and in vivo experiments were carried out to assess the potential frequency limit of the system and its intrinsic depth recovery accuracy. The potential applications of the technique include motion stabilization and intra-operative planning in the presence of large tissue deformation

Activity profiling for minimally invasive surgery

Imperial Users onl

A flexible access platform for robot-assisted minimally invasive surgery

Advances in Minimally Invasive Surgery (MIS) are driven by the clinical demand to reduce the invasiveness of surgical procedures so patients undergo less trauma and experience faster recoveries. These well documented benefits of MIS have been achieved through parallel advances in the technology and instrumentation used during procedures. The new and evolving field of Flexible Access Surgery (FAS), where surgeons access the operative site through a single incision or a natural orifice incision, is being promoted as the next potential step in the evolution of surgery. In order to achieve similar levels of success and adoption as MIS, technology again has its role to play in developing new instruments to solve the unmet clinical challenges of FAS. As procedures become less invasive, these instruments should not just address the challenges presented by the complex access routes of FAS, but should also build on the recent advances in pre- and intraoperative imaging techniques to provide surgeons with new diagnostic and interventional decision making capabilities. The main focus of this thesis is the development and applications of a flexible robotic device that is capable of providing controlled flexibility along curved pathways inside the body. The principal component of the device is its modular mechatronic joint design which utilises an embedded micromotor-tendon actuation scheme to provide independently addressable degrees of freedom and three internal working channels. Connecting multiple modules together allows a seven degree-of-freedom (DoF) flexible access platform to be constructed. The platform is intended for use as a research test-bed to explore engineering and surgical challenges of FAS. Navigation of the platform is realised using a handheld controller optimised for functionality and ergonomics, or in a "hands-free" manner via a gaze contingent control framework. Under this framework, the operator's gaze fixation point is used as feedback to close the servo control loop. The feasibility and potential of integrating multi-spectral imaging capabilities into flexible robotic devices is also demonstrated. A force adaptive servoing mechanism is developed to simplify the deployment, and improve the consistency of probe-based optical imaging techniques by automatically controlling the contact force between the probe tip and target tissue. The thesis concludes with the description of two FAS case studies performed with the platform during in-vivo porcine experiments. These studies demonstrate the ability of the platform to perform large area explorations within the peritoneal cavity and to provide a stable base for the deployment of interventional instruments and imaging probes