A Hydraulic Haptic Actuator for Simulation of Cardiac Catheters.

This article presents a haptic actuator made of silicone rubber to provide both passive and active haptic forces for catheter simulations. The haptic actuator has a torus outer shape with an ellipse-shaped inside chamber which is actuated by hydraulic pressure. Expansion of the chamber by providing positive pressure can squeeze the inside passage to resist the catheter traveling through.

Scaling behavior and text cohesion in Korean texts.

This study examines whether different types of texts, particularly in Korean, can be distinguished by the scaling exponent and degree of text cohesion. We use the controlled growth process model to incorporate the interaction effect into a power-law distribution and estimate the implied parameter explaining the degree of text cohesiveness in a word distribution. We find that the word distributions of Korean languages differ from English regarding the range of scaling exponents.

Effects of a Fluoroscopy Agent on Radio Opacity and Steering Performance of Pressure-Driven Steerable Micro Guidewire.

This paper presents experimental results of effects of a fluoroscopy agent on the radio opacity and steering performance of the steerable micro guidewire. The guidewire is driven by internal pressure, and made of the silicone polymer mixed with the barium sulfate, BaSO, masterbatch. Steerable distal tips with different BaSO densities up to 30 % are fabricated.

Adaptive surface representation based on homogeneous hexahedrons for interactive simulation of soft tissue cutting.

Background And Objective: Interactive simulation of cutting soft tissues is essential in simulation of surgery and medical procedures. Cutting simulation involves topological and geometrical changes of the finite elements, and requires significant additional computational burden. This problem is handled, in this paper, by approximating a small gap between the model boundaries and the volumetric finite elements.

Hydraulically Steerable Micro Guidewire Capable of Distal Sharp Steering.

Current steerable catheters or guidewires often cannot advance into small diameter vessels due to their large diameters or lack of sharp steering capacity. This paper proposes a hydraulically steerable guidewire with 400 μm diameter, which can access 1 mm diameter vessels whose branching angle is larger than 90 degrees. The designed steering mechanism consists of a flexible eccentric tube with inner micro patterns, which can bend in two different curvatures when pressurized.

Deformable objects modeling with iterative updates of local positions.

Background And Objective: Deformation of elastic material such as soft tissues of human body in the virtual environment is computed based on actual material properties. But this often leads to computational overhead hindering real-time simulation. This paper proposes a new modeling method of deformable objects for real-time simulation, using iterative updates of local positions, and control of the desired behavior by material properties.

Investigation on energy bandgap states of amorphous SiZnSnO thin films.

The variation in energy bandgaps of amorphous oxide semiconducting SiZnSnO (a-SZTO) has been investigated by controlling the oxygen partial pressure (O). The systematic change in O during deposition has been used to control the electrical characteristics and energy bandgap of a-SZTO. As O increased, the electrical properties degraded, while the energy bandgap increased systematically.

Grid Generation for Rendering Realistic X-ray Images of Narrow Blood Vessels in Real-time Angiography Simulation.

This paper proposes a method to generate grids to render realistic X-ray images of the narrow blood vessels in real-time angiography simulation. The vertexes of the narrow blood vessels are projected onto the image-rendering plane. The grids aligned in the vessel direction are generated using the projected boundary vertexes on the image-rendering plane.

A one-dimensional fluid simulation method of branching narrow vessel for real-time angiography simulation.

This paper proposes a one-dimensional fluid simulation method for real-time simulation of the contrast medium in a narrow blood vessel. A narrow vessel is modeled with the branches organized in a hierarchy. The density of the contrast medium on each branch is computed using the one-dimensional fluid model.

A hybrid contact model for cannulation simulation of ERCP.

This paper proposes a hybrid contact model, which enables an efficient simulation of cannulation procedure of ERCP. Meshless model and mass-spring model are employed together to construct the major papilla model. This method divides contact cases into visible and invisible contacts.

Markerless tracking for augmented reality for image-guided Endoscopic Retrograde Cholangiopancreatography.

This paper proposes a markerless tracking method with adaptive pose estimation for augmenting 3D organ models on top of the endoscopic image for Endoscopic Retrograde Cholangiopancreatography (ERCP). While many applications of augmented reality (AR) to surgeries need special markers to track the camera's position and orientation in the live video, our method employs the feature detection techniques to track the endoscopic camera. One of the most difficult problems when applying feature-based method to AR for ERCP is the lack of texture & highly specular reflection surface of duodenum in the endoscopic images, which does not provide a stable number of keypoints to track in the endoscopic video sequence.

Dynamic cylindrical free-form deformation for interactive simulation of tool-tissue interaction.

Background: Dynamic lattice-based free-form deformation (FFD) allows efficient simulation of global deformation of complex geometric objects. However, directly imposing a number of position constraints due to contact with a tool is non-trivial since it is an over-determined problem.

Method: This paper extends the FFD to directly impose a number of position constraints for the objects to be embedded in (rounded) cylindrical lattice structures.

Real-time deformation of colon and endoscope for colonoscopy simulation.

Background: Colonoscopy simulation has been increasingly applied as a method of training, which can supplement the traditional patient-based training in recent years. However, the current level of realism of the simulation is insufficient. One of the main difficulties degrading the realism is real-time simulation of colon deformation involving multi-contact interaction with the endoscope.

A design of hardware haptic interface for gastrointestinal endoscopy simulation.

Gastrointestinal endoscopy simulations have been developed to train endoscopic procedures which require hundreds of practices to be competent in the skills. Even though realistic haptic feedback is important to provide realistic sensation to the user, most of previous simulations including commercialized simulation have mainly focused on providing realistic visual feedback. In this paper, we propose a novel design of portable haptic interface, which provides 2DOF force feedback, for the gastrointestinal endoscopy simulation.

Real-time resolution of self-intersection in dynamic cylindrical free-form deformation.

This paper presents a method of self-intersection detection and resolution for dynamic cylindrical-lattice-based free-form deformation (FFD). The lattice-based approach allows efficient computation of deformation of complex geometries. But excessive deformation can cause visual anomalies such as surface infiltration and distortion.

GPU-based real-time soft tissue deformation with cutting and haptic feedback.

This article describes a series of contributions in the field of real-time simulation of soft tissue biomechanics. These contributions address various requirements for interactive simulation of complex surgical procedures. In particular, this article presents results in the areas of soft tissue deformation, contact modelling, simulation of cutting, and haptic rendering, which are all relevant to a variety of medical interventions.

Estimation of environmental force for the haptic interface of robotic surgery.

Background: The success of a telerobotic surgery system with haptic feedback requires accurate force-tracking and position-tracking capacity of the slave robot. The two-channel force-position control architecture is widely used in teleoperation systems with haptic feedback for its better force-tracking characteristics and superior position-tracking capacity for the maximum stability margin. This control architecture, however, requires force sensors at the end-effector of the slave robot to measure the environment force.

Sectional Analysis of Learning on the KAIST-Ewha Colonoscopy Simulation II.

The goal of this study is to validate the KAIST-Ewha Colonoscopy Simulation II as a training tool by examining the sectional learning curve of the trainees' performance on the simulation. Nine subjects including three fellows and six residents in the internal medicine participated in this study. All the subjects practiced the colonoscopy on the simulation until their performance surpasses the criteria preset by colonoscopy experts.

Haptic control with environment force estimation for telesurgery.

Success of telesurgical operations depends on better position tracking ability of the slave device. Improved position tracking of the slave device can lead to safer and less strenuous telesurgical operations. The two-channel force-position control architecture is widely used for better position tracking ability.

Enhancement of kinesthetic perception for microsurgical teleoperation using impedance-shaping.

A new control scheme is developed in this paper for a bilateral teleoperation system for microsurgical applications. The main objective of the proposed control scheme is to enhance the kinesthetic perception of the operator. First, the kinesthetic perception, based on psychophysics, is classified into three metrics of detection, sensitivity of detection, and discrimination.

Haptic interface of the KAIST-Ewha colonoscopy simulator II.

This paper presents an improved haptic interface for the Korea Advanced Institute of Science and Technology Ewha Colonoscopy Simulator II. The haptic interface enables the distal portion of the colonoscope to be freely bent while guaranteeing sufficient workspace and reflective forces for colonoscopy simulation. Its force-torque sensor measures the profiles of the user.

Improvement of colonoscopy skills through simulation-based training.

The objective of this study is to determine whether targeted colonoscopy skills are acquired through simulation-based training using the KAIST-Ewha Colonoscopy Simulator II, and the acquired skills can be transferred to colonoscopy to actual patients. Eleven subjects consisting of six fellows and five residents participated in the study. The fellows and residents were divided into two groups, simulation-trained group and control group.

Novel virtual Lap-Band simulator could promote patient safety.

This paper presents, for the first time, a physics-based modeling technique for the Lap-Band (Inamed Health) used in laparoscopic gastric banding (LAGB) operations for treating the morbidly obese. A virtual LAGB simulator can help train medical students as well as surgeons who embark at learning this relatively new operation. The Lap-Band has different thickness and curvature along the centerline, and therefore leads to different deformation behaviors.