Jingsi Zhang

Virtual Surgery Deformable Modelling Employing GPU Based Computation

The development of Virtual Environment (VE) systems is a challenging endeavor with a complex problem domain. The experience in the past decade has helped contribute significantly to various measures of software quality of the resulting VE systems. However, the resulting solutions remain monolithic in nature without addressing successfully the issue of system interoperability and software aging. This paper argues that the problem resides in the traditional system centric approach and that an alternative approach based on system of systems engineering is necessary. As a result, the paper presents a reference architecture based on layers, where only the core is required for deployment and all others are optional. The paper also presents an evaluation methodology to assess the validity of the resulting architecture, which was applied to the proposed core layer and involving individual sessions with 12 experts in developing VE systems.To achieve the real-time requirement of realistic deformable modelling, it is necessary to use the acceleration techniques such as GPU computing for FEM and employ the feasible hybrid structures in a virtual surgery simulation system. In this paper, we present a linear or nonlinear deformable model of soft tissue. In addition to the efficient meshing and basic finite element method, the high computation rate is achieved through two novel methods. Firstly, the major calculation work in the conjugate gradient solver for deformation is moved from the CPU to GPU in order to promote the calculation. Secondly, we apply the hybrid structures of deformable models, by fully calculating the volumetric deformation in the local operation part while only calculating the global deformation by medial representation method. Experiments have been given to show the feasibility and efficiency of the model.

An advanced hybrid cutting method with an improved state machine for surgical simulation

In this work, a novel hybrid cutting method combining non-progressive cutting with progressive cutting is proposed, where progressive cutting is applied on the outer hull while non-progressive cutting is applied in the inner core. Therefore it keeps the visual reality while significantly increases the efficiency and stability for consequent soft-tissue simulation. In addition, we combined the nearest node snapping with the subdivision patterns in topology reconstruction to avoid degeneracy which is disastrous to soft-tissue simulation stability. Furthermore, an improved state-machine with shortcut transition is used to improve efficiency. The approach has been integrated into a virtual laparoscopic surgery training system.

Hierarchical spatial hashing-based collision detection and hybrid collision response in a haptic surgery simulator

Collision detection and response are two crucial aspects in a virtual surgery simulator, which significantly affect the output in real‐time response and simulation realism.

Computer-assisted Preoperative Planning and Surgical Navigation System in Dental Implantology

This paper presents a construction of a computer assisted system in dental implantology. Preoperative planning and surgical navigation are two main sub-systems in our proposed system. In the preoperative planning subsystem, we provide different kinds of views to the surgeons based on CT data scanned for a specific patient. And the surgical navigation subsystem uses an infra-red light based navigation camera to locate the precise position of the surgical instrument. The two subsystems will combine together to form a seamless linked all-in-one system for dental implantological surgery. Due to the tight connection between the two subsystems, the depth and orientation of drilling will be tracked under the same coordinate space, which will guarantee the accuracy of match between the preoperative planned position and the realtime navigated position. The main objective of this paper is to present how to build such a system under the direct clinical requirement from dentists. At last, the experiments in phantom study demonstrate that the mean errors of the depth and the angle are 0.772 (mm) and 0.554 (degree) respectively

Simulation of organ deformation using boundary element method and meshless shape matching

In this paper, a novel approach to perform real-time simulation of the deformation of anatomical organs is proposed for virtual surgery study. The method, which is both physics and interactivity motivated, is composed of two algorithms: boundary element method and meshless shape matching. We employ boundary element method to simulate a precise global deformation, and use meshless shape matching method to achieve low latency. In addition, a state machine is applied to control the computation patterns of deformation. The initial experiment reveals that the proposed approach can simulate organ deformations both efficiently and accurately.

Real-time virtual surgery simulation employing MM-model and adaptive spatial hash

In this paper, MM-Model is presented for real-time simulation of 3D deformable objects on both global level and local region. This model consists of a deformable centerline and dynamic surface reconstruction mechanism based on Mass-Spring and Medial-Representation respectively. When a relatively small force is applied on the object the model works in the same way as the traditional Mass-Spring. Otherwise the force is directly transferred to the centerline and the surface is dynamically recreated according to the position of the centerline. This model works more effectively and efficiently than traditional elastic ones on the global level due to the advantages of the Medial-Representation reflecting the internal information and the Mass-Spring reducing the response time. A novel collision detection algorithm based on adaptive spatial hash, a cutting approach and suture method are also articulated. An artificial blood vessel’s deformation effect and surgery processes are presented in our case study.

A novel laparoscopic surgery simulator: System and evaluation

A full-fledged surgery simulator should provide functions which really train and improve surgeonspsila skill. In this work, we comprehensively illustrate our surgery simulation system from its function, architecture and methods. Next, we evaluated our system from the doctorspsila perspective. Surveys are carried out to investigate doctorspsila experience of the system. Experiments are conducted to record their skill improvement during a certain period of time of training using our system. From the evaluation, some valuable points were concluded for future research direction.

Image-guided surgery planning for breast reconstruction flap design

In this paper, a computer aided breast reconstruction surgery planning method is proposed, computing the breast shape after excision of one for some diseases such as cancer. In order to achieve a reasonable result, we calculate shape, area, volume and depth of the skin and muscle for the reconstruction, based on another wholesome breast. The solution is described as follows: firstly, the breasts MRI data of patient is input; then, the region of interest is obtained from healthy breast employing balloon segmentation algorithm and retrieve surface mesh data; thirdly, the dimensional surface skin mesh is mapped onto the plane, in order to attain the shape and volume of the flap for breast reconstruction, by the help of deformable model; finally the approximate curve volume shape of flap is calculated. Other contributing methods such as mesh smoothing and cutting of triangulated surface are also discussed. The doctors validation and evaluation process are also provided to ensure the robust and stable result of virtual surgery planning.

A Method for Collision Response between Deformable Objects in Virtual Surgery

Virtual surgery has drawn a lot of attention during the past few years for its repeatability and low cost. In a virtual surgical environment, collision between organs or between organs and surgical instruments occurs frequently. Therefore, an efficient and stable method is needed to simulate these collision processes. Nevertheless, contrary to rigid solid animation where complete analytical solutions have been found, simulating colliding response process between deformable objects still remains a challenge. In this paper, we present an advanced method to model collision response between tissues. It computes response force and generates an exact contact surface between colliding objects. Our method considers both geometric features such as penetration depth and physical properties such as relative velocity and friction to compute proper collision forces. Further, a breadth-first searching algorithm is applied in distributing these calculated reaction forces in different parts of the object in order to generate exact contact surface between interacting objects. Its application in a minimal invasion virtual surgery is used for case study.

A Hybrid Collision Response in a Haptic Virtual Surgery System

Collision response is an important component in a virtual surgery system, due to the requirements of realtime response and simulation realism. In this paper, we propose a novel hybrid collision response algorithm for generating a smooth feedback force. This algorithm takes the advantages of three traditional methods as well as gets rids of drawbacks of them. It also provides an approach to generate a reasonable feedback force. After collision response processing the variance of feedback force has been reduced from 30026 to 0.0003, form 39095 to 0.06 and from 5455 to 0.008 in x, y and z dimension respectively. The result shows that our methods can be used in a real-time response and simulation realism required haptic surgery simulator.