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Biomedical subjects

Megumi Nakao

Publications and source records attributed to Megumi Nakao.

8 recordsLinked to original sources

Physics-based simulation of surgical fields for preoperative strategic planning.

Although careful planning of surgical approach is a key for success of surgery, conventional planning and simulation tools cannot support detailed discussion. This issue is derived from the difficulty of estimating complex physical behavior of soft tissues provided by a series of surgical procedures like cutting and deformation. This paper proposes an adaptive physics-based framework that simulates both interactive cutting and accurate deformation on virtual bodies, and performs preoperative planning for supporting strategic discussion. We focus on limited use of the two models: A particle-based model and an FEM-based model considering required quality and performance in different situations. FEM-based deformation of incision accurately produces estimated surgical fields. Based on the framework, a strategic planning system was developed for supporting decision of surgical approach using 3D representation of the surgical fields. We applied clinical CT dataset of an aortic aneurysm case to the system. Some experiments and usability tests confirmed that the system contributes to grasping 3D shape and location of the target organs and performs detailed discussion on patient-specific surgical approaches.

Aortic Aneurysm↗

Interaction model between elastic objects for haptic feedback considering collisions of soft tissue.

The simulation of organ-organ interaction is indispensable for practical and advanced medical VR simulator such as open surgery and indirect palpation. This paper describes a method to represent real-time interaction between elastic objects for accurate force feedback in medical VR simulation. The proposed model defines boundary deformation of colliding elements based on temporary surface forces calculated by temporary deformation. The model produces accurate deformation and force feedback considering collisions of objects as well as prevents unrealistic overlap of objects. A prototype simulator of rectal palpation is constructed on general desktop PC with a haptic device, PHANToM. The system allows users to feel different stiffness of a rear elastic object located behind another elastic object. The results of experiments confirmed the method expresses organ-organ interaction in real-time and produces realistic and perceivable force feedback.

Computer Simulation↗

FEM-based soft tissue destruction model for ablation simulator.

In surgical procedures, ablation is one of the most difficult skills to train and acquire. For the risk of ablation failure, ablation training environments are desired. This paper proposes FEM-based deformation and destruction soft tissue model for ablation training simulator. The proposed model employs shearing stress hypothesis. The result of simulation experiments shows that the model can express different destruction progression by manipulation.

Catheter Ablation↗

MVL: medical VR simulation library.

In the last ten years, medical VR techniques have much progress and many simulators have been developed for education, planning, rehearsal and so on. On the other hand, developing a simulator takes much more labor and cost. In this paper, we propose MVL: Medical Virtual reality simulation Library, which supports simulation of several significant medical manipulations considering multiple organ interaction. The result of developing simulators using MVL confirmed validity about variety and developing cost.

Computer Simulation↗

Interactive 3D region extraction of volume data using deformable boundary object.

This study aims to establish an interactive and intuitive region extraction environment for volume data. A volume clipping method using deformable boundary object is proposed to support 3D region extraction task. Slice-based volume rendering of boundary elements enables to visualize clipped results in real time. Geometrical transformation and physics-based deformation support intuitive modification of 3D region of interest. Some extraction tasks are tested using CT data set on the developed system. All tests confirmed real-time visualization of clipped results is effective for interactive 3D region extraction in volume visualization and virtual object modeling.

Elasticity↗

FEM-based interaction model between elastic objects for indirect palpation simulator.

Indirect palpation is required to examine lots of cases like breast cancer and prostate malignance. This paper proposes interaction model between elastic objects to simulate indirect palpation. The interaction is simulated by displacement of colliding elements based on normal stress derived from temporary displacement. The physics-based approach represents the difference of physical properties such as stiffness of colliding objects. Deformation and haptic reproduction is possible to be carried out in real time with two organ models consisting of roughly 200 nodal points. As an example, we developed a rectal palpation simulator based on the proposed method. The experiment using rectal palpation simulator confirmed that the method enables a user to perceive difference of stiffness of prostate model located behind rectum model indirectly.

Computer Simulation↗

Physics-based preoperative approach planning using hybrid virtual bodies.

This paper proposes a hybrid model mixing geometry and volume data to improve representation of virtual bodies. This model applies object-oriented data models and rendering techniques to virtual organs, and enables both interactive VR simulation and detailed volume visualization of tissue of interest (e.g. coronary). Also, a physics-based framework interactively simulates estimated surgical fields which are used in preoperative discussion. Based on the proposed methods, a VR-based strategic planning system is developed. The system does not need high cost manual segmentation of patient dataset and efficiently supports planning of surgical approaches in cardiovascular surgery.

Humans↗

Practical haptic navigation with clickable 3D region input interface for supporting master-slave type robotic surgery.

Conventional display in robotic surgery such as flat displays or stereoscopic displays decreases obtainable information around target tissue. For supporting manipulation and performing safe surgery, this paper proposes a haptic navigation method, which enables surgeons to avoid collision with untouchable regions around target tissue by producing force feedback through a master manipulator. This paper also developed an input interface for assignment of 3D untouchable regions through 2D device. Simulator based experiment clears effectiveness of the proposed haptic navigation for improving safety of robotic surgery.

Humans↗