Virtual brain surgery simulation system based on haptic interaction

To improve the accuracy and interactivity of soft tissue delormatlon simulation, a new plate spring model based on physics is proposed. The model is parameterized and thus can be adapted to simulate different organs. Different soft tissues are modeled by changing the width, number of pieces, thickness, and length of a single plate spring. In this paper, the structural design, calcula- tion of soft tissue deformation and real-time feedback operations of our system are also introduced. To evaluate the feasibility of the system and validate the model, an experimental system of haptic in- teraction, in which users can use virtual hands to pull virtual brain tissues, is built using PHANTOM OMNI devices. Experimental results show that the proposed system is stable, accurate and promising for modeling instantaneous soft tissue deformation.

A Novel Twist Deformation Model of Soft Tissue in Surgery Simulation

Real-time performance and accuracy are two most challenging requirements in virtual surgery training.These difficulties limit the promotion of advanced models in virtual surgery,including many geometric and physical models.This paper proposes a physical model of virtual soft tissue,which is a twist model based on the Kriging interpolation and membrane analogy.The proposed model can quickly locate spatial position through Kriging interpolation method and accurately compute the force change on the soft tissue through membrane analogy method.The virtual surgery simulation system is built with a PHANTOM OMNI haptic interaction device to simulate the torsion of virtual stomach and arm,and further verifies the real-time performance and simulation accuracy of the proposed model.The experimental results show that the proposed soft tissue model has high speed and accuracy,realistic deformation,and reliable haptic feedback.

Application of a medical image processing system in liver transplantation

BACKGROUND: At present, imaging is used not only to show the form of images, but also to make three-dimensional (3D) reconstructions and visual simulations based on original data to guide clinical surgery. This study aimed to assess the use of a medical image-processing system in liver transplantation surgery. METHODS: The data of abdominal 64-slice spiral CT scan were collected from 200 healthy volunteers and 37 liver cancer patients in terms of hepatic arterial phase, portal phase, and hepatic venous phase. A 3D model of abdominal blood vessels including the abdominal aorta system, portal vein system, and inferior vena cava system was reconstructed by an abdominal image processing system to identify vascular variations. Then, a 3D model of the liver was reconstructed in terms of hepatic segmentation and liver volume was calculated. The Free Form modeling system with a PHANTOM force feedback device was used to simulate the real liver transplantation environment, in which the total process of liver transplantation was completed. RESULTS: The reconstructed model of the abdominal blood vessels and the liver was clearly demonstrated to be three-dimensionally consistent with the anatomy of the liver, in which the variations of abdominal blood vessels were identified and liver segmentation was performed digitally. In the model, liver transplantation was simulated subsequently, and different modus operandi were selected successfully. CONCLUSION: The digitized medical image processing system may be valuable for liver transplantation.

A virtual reality based surgical skills training simulator for catheter ablation with real-time and robust interaction

Background Atrial fibrillation(AF)is the most common sustained cardiac arrhythmia that can cause severe heart problems.Catheter ablation is one of the most ideal procedures for the treatment of AF.Physicians qualified to perform this procedure need to be highly skilled in manipulating the relevant surgical devices.This study proposes an interactive surgical simulator with high fidelity to facilitate efficient training and low-cost medical education.Methods We used a shared centerline model to simulate the interaction between multiple surgical devices.An improved adaptive deviation-feedback approach is proposed to accelerate the convergence of each iteration.The periodical beating of the human heart was also simulated in real time using the position-based dynamics(PBD)framework to achieve higher fidelity.We then present a novel method for handling the interaction between the devices and the beating heart mesh model.Experiments were conducted in a homemade simulator prototype to evaluate the robustness,performance,and flexibility of the proposed method.Preliminary evaluation of the simulator was performed by medical students,residents,and surgeons.Results The interaction between surgical devices,static vascular meshes,and beating heart mesh was stably simulated in a frame rate suitable for interaction.Conclusion Our simulator is capable of simulating the procedure of catheter ablation with high fidelity and provides immersive visual experiences and haptic feedback.

Real Time and Efficient Haptic Feedback Framework for Deformable Objects

On account of the high computational speed required for force feedback and the detailed graphic required for deformation feedback, this paper presents a real time and efficient haptic feedback framework by subdividing the area of interest on a relatively coarse triangular mesh. When a contact is detected, a portion of the colliding surface is subdivided and a particle system produced, which is used for deformation based on the approximate velocity cone theory. Simultaneously, a spring\|damper model is used ...

A novel progress of leg tissue properties modeling based on biomechanics

To describe strategies for addressing technical aspects of computational modeling of leg tissue with the finite element （FE） method, a patient＇s leg sample was selected and scanned by CT at the direction parallel to the Frankfort Horizontal plane. A three-dimensional （3D） finite element model of the human leg was developed using the actual geometry of the leg skeleton and soft tissues, which were obtained from 3D reconstruction of CT images. All joints were defined as contact surfaces, which allow relative articulating movement. The major ligaments were simulated using tension-only truss elements by connecting the corresponding attachment points on the bone surfaces. The bony and ligamentous structures were embedded in a volume of soft tissues. The muscles were defined as non-linear viscoelastic material, and the skin, ligaments and tendons were defined as hyperelastic, while the bony structures were assumed to be linearly elastic. The muhilayer FEM model containing thighbone, tibia, fibula, kneecap, soft tissue was formed after meshing. Diverse forces were imposed on the FEM model. The results show that the multilayer FEM model can represent tissue deformation more accurately.

Computer-Aided Simulation of Mastoidectomy

Objective To establish a three-dimensional model of the temporal bone using CT scan images for study of temporal bone structures and simulation of mastoidectomy procedures. Methods CT scan images from 6 individuals (12 temporal bones) were used to reconstruct the Fallopian canal, internal auditory canal, cochlea, semicircular canals, sigmoid sinus, posterior fossa floor and jugular bulb on a computer platform. Their anatomical relations within the temporal bone were restored in the computed model. The same model was used to simulate mastoidectomy procedures. Results The reconstructed computer model provided accurate and clear three-dimensional images of temporal bone structures. Simulation of mastoidectomy using these images provided procedural experiences closely mimicking the real surgical procedure. Conclusion Computer-aided three dimensional reconstruction of temporal bone structures using CT scan images is a useful tool in surgical simulation and can aid surgical procedure planning.

Digital medical technology based on 64-slice computed tomography in hepatic surgery

Background With the rapid development of computer technology, digital medicine has become a new direction in surgery. The application of digital medicine in hepatic surgery is still at the early stage and less reported in the literature. The aim of this study was to apply digital medical technology in the context of hepatic surgery. Methods Data from 64-slice helical computed tomography of 17 patients, including 13 with hepatocellular carcinoma and 4 with hepatic hemangioma, were imported into independently developed medical image software program, segmentation and three-dimensional reconstruction were performed. The three-dimensional models were then processed with the FreeForm Modeling System. We used virtual surgical instruments to perform surgery on the models. Simulated surgeries included six hepatic segmentectomies, four left hemihepatectomies, three right hemihepatectomies for hepatocellular carcinoma, one hepatic segmentectomy, two stripping surgeries, and one irregular segmentectomy combined with stripping surgery for hemangioma. For resections involving more than three hepatic segments, total and residual functional hepatic volumes were measured before and after simulation surgery, and the resection ratio was calculated.Results The anatomy of the models was distinct and was used to localize lesions. We used virtual surgical instruments to perform simulated surgeries and used the models to optimize actual surgeries. We were able to minimize resection volume as well as surgical risk.Conclusions Digital medical technology is helpful in the diagnosis of hepatic disease and in optimizing surgical plans. Three-dimensional models can decrease surgical risk and help prevent postoperative hepatic failure.