Sanghyun Joung

Dual surgical navigation using augmented and virtual environment techniques

To obtain additional depth and visual information in endoscopic surgery, a dual surgical navigation system using virtual reality (VR) and augmented reality (AR) techniques complementarily was developed. A VR environment was constructed in the default 3-D view of the navigation software and an AR environment was developed as a plug-in module. The spatial relationships among the target organ, endoscope, and surgical tools were visualized, and the visual information superimposing invisible organs on the endoscopic images was supplied using the AR environment. Phantom experiments and preliminary clinical application showed promising results for surgical navigation.

A Robot Assisted Hip Fracture Reduction with a Navigation System

A fracture reduction robot is described as assisting in safe and precise fracture reduction. The robot is connected with pins that are inserted into the patients bone fragments, together with a customized jig. The robot has six degrees of freedom with high precision, so that precise fracture reduction can be conducted. The failsafe unit of the fracture reduction robot can mitigate excessive reduction force that may cause complications such as avascular necrosis. We have integrated the fracture reduction robot with a navigation system that tracks the relative position of the bone fragments and generates the reduction path. The integrated system is evaluated with the simulated fracture reduction of a hip fracture model (n = 8). Three-dimensional parameters related to the mechanical axis--the proximal femur angle, the distal femur angle, and the length of the mechanical axis--were evaluated by comparing the normal values with those after reduction; these average differences are 1.76 degrees , 0.28 degrees and 0.76mm, respectively. The automated fracture reduction feature makes it possible for medical staff to work at a distance from radiation sources; for patients, the integrated fracture reduction system has the potential to reduce fractures with high precision.

Hazard analysis of fracture-reduction robot and its application to safety design of fracture-reduction assisting robotic system

In this paper, we discuss the issue of safety in robot-assisted fracture reduction. We define the hazards of robot-assisted fracture reduction and design safety control methods. Although a large reduction force is required to reduce femoral neck fractures, an unexpectedly large force produced by a robot may cause injury to the patient. We have designed two mechanical failsafe units and a software force limiter; this along with velocity control can guarantee a safe operation in reduction force. In addition, to reduce the movement of bone fragments as much as possible, we devised spatially constrained control methods for fracture-reduction robots. The fracture-reduction system was evaluated using simulated fracture reductions.

Safe and minially invasive palpaiton device for detection of lung tumor during thoracoscopic Surgery

Though palpation is useful method to detect pulmonary nodules with open thoracotomy, it is very difficult in case of thoracoscopic surgery. We have developed a palpation device to this end. A pressure sensitive conductive rubber is used to measure hardness of tissue. The diameter of sensor units is small enough to pass thorough a trocar. The pressure-output property of the sensor unit was evaluated at laboratory. We could detect the tumor model in lung from in vivo experiments. Safety mechanism that limits the pressure applied by the palpation device was proposed. We are plan to apply the palpation device to endoscopic based navigation system.

Real-time Visualized Vessel and Catheter Path Reconstruction for Intravascular Intervention

Minimally invasive intravascular intervention is performed with the aid of catheters for therapy. We apply intra-operative freehand ultrasound and tracked catheter for guiding intravascular intervention. Current freehand 3D ultrasound techniques separate the scanning or acquisition step from the visualization step. This leads to no feedback during image acquisition. The reconstruction quality is highly dependent on scanning experience. A low-quality imaging even causes re-scanning and prolongs the time of image acquisition. In addition, the catheter path is important information implying the skeleton of the target vessel. It also helps doctor understand the catheter position relative to vessels for reducing the risk of vessel injuries. We developed a catheter navigation system that will allow real-time visualizing the scanned vessel volume as well as catheter path. The system consists of a freehand US for vessel reconstruction, an electromagnetic tracking system for locating the position and orientation of the ultrasound probe and catheter tip, a video frame grabber for capturing ultrasound frames, and a typical PC for performing real-time reconstruction and scene rendering. The system incorporates novel methods for visualizing data acquisition of image guided intravascular intervention in real time. This paper reports on current work in progress, and focuses on methods to achieving real-time visualizing reconstructions of freehand 3D ultrasound and catheter path. We demonstrate the system on a vessel phantom. The results suggest the system could visualize the reconstruction in real-time.

Direct minimally invasive intraoperative electrophysiological mapping of the heart

Abstract Introduction: Cardiac electrophysiology aims to describe and treat the electrical activity of the heart. Although an epicardial approach is valuable in many surgical treatments such as coronary artery bypass grafting, maze ablation, and cell transplantation, very few techniques suited for minimally invasive surgery are available for measurement of epicardial electrophysiology. Material and methods: We developed a novel endoscopically-deployable expanding electrode array that can be applied for minimally invasive surgery. Our device consists of a flexible electrode array attached to arms which open and close the electrode sheet. Furthermore, we also developed a computer program to overlay an epicardial electrophysiological map on an endoscopic image. We performed both laboratory and in vivo experiments to examine the feasibility in clinical situations. Results: Evaluation experiments demonstrated that our novel mapping process that assumes spherical deformation of the electrode array enables us to overlay each electrode position with an accuracy of < 1 mm. Results of animal experiments using large animals (one dog and two pigs) demonstrated that our system enables construction of epicardial electrophysiological maps. Conclusion: A novel endoscopically deployable expanding electrode array was developed. Evaluation experiments demonstrated that our device can be manipulated in simulated minimally invasive surgery, and enables construction of epicardial electrophysiological maps.

Electrode array tracking and manipulating for robot assisted epicardial electrophysiological mapping

A small electrode array manipulable by a surgical robot was developed and evaluated through an in vivo experiment. And this paper proposes a new tracking method for locating an electrode array in a robot assisted arrhythmia surgery using an endoscopic stream. Tracking accuracy was also evaluated by a computer simulation and a preliminary laboratory performance test. Consequently, this new small electrode array and our proposed electrode array tracking method enable the global epicardial electrophysiological mapping system to be integrated with a robot assisted arrhythmia surgery.

A spherical bone cutting system for Rotational Acetabular Osteotomy

We have developed a spherical bone cutting system to assist Rotational Acetabular Osteotomy (RAO), which is efficient treatment of hip dysplasia. The system consisted of two units: a bone cutting device and a device manipulation system for controlling the position and posture of the bone cutting device. Clinical usefulness of the bone cutting device was evaluated from the cutting experiments of porcine pelves. Using water-irrigation of 10ml/min fluid during the bone cutting procedure, maximum temperature was lower than 40 degrees centigrade, which is enough to avoid heat-induced bone necrosis. The resected width, 2.0–2.2mm, is also acceptable for the bone regeneration. And we validated that intended cutting was performed by measuring 3-dimensional surface position of the cut porcine pelves. Cutting experiment using the bone cutting system was performed at human pelvis model to estimate the movable extant of the system.