| BackgroundIn recent years, with the three-dimensional medical imaging technology and computer technology and the mutual penetration, three-dimensional reconstruction of the simulation surgery to become a research focus. He is a medical, bio-mechanics, mechanics and computer graphics such as a cross-disciplinary research in the field, the purpose is to apply computer technology to simulate and guide medical surgical processes involved, the scope of application in medicine is increasingly wide.The images from CT and MRI can be managed to reconstruct three dimensional moulds of human tissues and organs by three dimensional visualization techniques. Doctor can visualize the interested part and show the three dimensional structures, and can observe from any view angles and measures these anatomical structures. Doctor also can make sure of the space location and size and shape of fracture and accurately determine the type of fracture, geometric shape and structure with the relationship between each other. Surgical design and virtual surgery also can be carried out by virtual reality techniques on the three dimensional moulds.Virtual reality is an integrated human and information science, the core is by some computer-generated three-dimensional interactive environment, whose purpose is through the experience to that of synthetic information. With virtual reality technology, complex or abstract systems and the concept of the system through the various sub-components represented in some way with the exact meaning of the symbols possible. We name it virtual surgery to apply virtual reality techniques in surgery. Treating medical images is the first step for virtual surgery. And then the human tissues and organs moulds are reconstructed in computer. A virtual environment is established and doctor immerses in it through a variety of sensing equipment which providing watching,listening,speaking,force,touching,acting,and so on. Doctor can achieve surgical design and do operative training and induct operating in true surgery with the help of the information providing by virtual environment.Although virtual surgery system has great clinical importance, it wasnt widely equipped in hospital in the past. Two deficiencies of it restrict its application. The first is that the result of visualization in the system was not precise enough and the speed of visualization is too slow for interaction. The second is the difficulty of simulation of section, while without section it is impossible to inspect organs under the surfaces. It need a long time to build the Chinese VR preoperative program data bank.In this study, image segmentation and 3D reconstruction methods to improve and perfect, by 64-slice spiral CT scan data from the hip fracture procedures for image segmentation and three-dimensional computer reconstruction, and clinical data, various common visual hip fracture Application of simulation surgery. Through this study, we can construct a fracture site can display three-dimensional geometric model of the structure will fracture the skin and blood vessels can form three-dimensional "reality" show up, you can visualization. The innovation of this study is accurate in space in the fracture site with three-dimensional positioning, three-dimensional from all angles can be observed fracture of anatomical structure, measuring a variety of data, can be simulated fractures, and fracture patients can use a variety of images (CT, MRI, etc.) scan data for image fusion and updated so that surgeons can easily to various computers on the femur fracture risk prediction, individual surgical program development, operation and clinical Shi process simulation exercises to teach, to enhance the surgical skills and surgical safety to reduce the complications.ObjectiveTo study the methods of three dimensional reconstruction on femur and soft tissue based on 64-slice spiral CT scanning data;To establish femur fracture hepatic surgery training system based on the moulds of femur and soft tissue;To investigate the clinical significances of surgical design and virtual surgery before fracture surgery based on femur fracture hepatic surgery training system.Methods1. Study on three dimention and visualization of femur and soft tissue based on 64-slice spiral CT scanning data(1) Subject:One male patient was suffered by right Intertrochanteric fracture I B type(Evans-Jensen classification),with 1.74 meters tall and 66 kg weight. Another male patient was suffered by left femur supracondylar fracture Cl type(AO classification).(2)64-slice CT raw data collection:The data was from 64-slice spiral CT-PHILIPS Brilliance 64(Netherlands). Scanning conditions:voltage 120KV, thickness 0.625mm, matrix 512×512. Image post-processing workstations was PHILIPS Brilliance 64-slice CT onboard Mxview workstations. Plain thin and dynamic enhanced CT scan on the fracture were carried out, and the CT scaning data was burned with discs for standby. (3)Image segmentation and 3D reconstruction:DICOM browser was used to read the CT data, and the CT data was converted to format JPEG. And then they were converted to format BMP from JPEG by ACDSee 9.0. Segmentation and reconstruction were completeted in Mimics10.0 software through successive steps. Algoritlhm of auto adapted region growing was applied for segmentation. It was set for the gray scale threshold generally ranging from 5 to 10 according to the gray scale homogenicity of object tissue in Mimics10.0. A send point was selected as an initial point in region of interest(ROI) and the contour line of tissue was segmentated. The contour lines of tissues segmentated were reconstructed for three dimension moulds by surface based rendering, and moulds were exported and saved with format STL. The images datas were imported to FreeForm Modeling System for smoothing and decorating. Key "Select" was used to build the three dimensional moulds of transverse section,coronal section, Y axes section and oblique section.2. Setting up the femur fracture surgery training system based on the moulds of femur(1) Modeling surgical instrumentsIn UG4.0 modeling module, the use of modeling the characteristics of the module operation and forming characteristics of functions and features using sketches, using vernier caliper original measurement data modeling, to prt file suffix save. Dynamic hip screw (dynamic hip screw, DHS) system built instruments are guided needle, guide, DHS triple reamer, tap, plate, screws and so on. AO invasive stabilization system (less invasive stable system, LISS) System Construction of instruments sleeve, locking screw, bolts, screws, etc.. LISS plate and a guide number of hand-made by Shanghai Science and Technology Co., Ltd.3DSS binocular series of three-dimensional optical scanner access. Retrograde intramedullary nail system (GSH nail) nail in need of renewal, guide, locator, on poles, guide rods and screws, etc., all equipment can require different levels of simplified or exaggerated to meet different requirements. The above figures are the output STL file format. (Surgical instruments provided by the Shanghai synthes company)(2)Setting up the femur fracture hepatic surgery training systemThe three dimensional moulds of femur and soft tissue used in this part were from the achievement of the first part. The three dimensional moulds of femur and soft tissue were imported into FreeForm Modeling System. Then the surgery instruments were imported into FreeForm Modeling System developed by software UG4.0.2. Setting up the femur fracture surgery training system based on the moulds of femurFemur fracture surgery training system used in this part was from the achievement of the second part.Surgical design and Virtual surgery for femur intertrochanteric fractureThe femur fracture surgery training system was switched on in FreeForm Modeling System. The space relationships of the fractures were observed by seeing through and turning and magnifying three dimensional moulds. According to the operative plan, select the appropriate surgical approach. According to fracture displacement situation, design reduct method. After reduction, using LISS plate and GHS nail virtual fixation.Surgical design and Virtual surgery for femur supracondylar fractureThe femur fracture surgery training system was switched on in FreeForm Modeling System. The space relationships of the fractures were observed by seeing through and turning and magnifying three dimensional moulds. According to the operative plan, select the appropriate surgical approach. According to fracture displacement situation, design reduct method. After reduction, using DHS nail virtual fixation.Results1. The results of data collectionThe data collection for 64 thin-slice CT scanning of femur:the femur intertrochanteric fracture got 457 piece of scanning images, with a total of 332MB of data; femur supracondylar fracture got 431 piece of scanning images,with a total of 479 MB of data.2. The results of three dimensional reconstructionTwo subjects of data through self-developed image segmentation medical image processing software Mimics10.0 three-dimensional reconstruction and smooth through the FreeForm Modeling System, micromachining, The three-dimensional model of fracture section and the surrounding muscle and skin are clear, realistic, stereoscopic can be from a different angle zoom, and full rotation and perspective to observe the fracture section of the surrounding skin and muscles between the three-dimensional structure of relations. In the three-dimensional model, we can find a lot of CT images can not display the important information. For example, the fracture of three-dimensional anatomical relationship between paragraphs. These important information that can guide us in the risk assessment procedure before surgery, reduction assessment.3. The results of femur fracture surgery training systemThe femur fracture surgery model and the actual the femur structure is very similar, each fracture segment and their organizations such as skin and muscle are morphology realistic, three-dimensional. The internal fixation device model three-dimensional structure is very realistic. We can manipulate surgical instruments to perform procedures by PHANTOM. Femur fracture in a virtual surgery system, the operator can manipulate surgical instruments, simulated cutting, drilling, inserting and stitching and other activities. In the surgical operation, the operator can get to a certain extent the actual operation of the handle, that is, the intensity of feeling. The use of virtual surgical environment, through the manipulation of surgical instruments, to simulate the internal fixation of the operation, including the cutting operation, the assembly of internal fixation, intramedullary nail plate and screw the screw into the implant and so on. Fracture fixation accurate simulation, realistic and have a strong presence. The system will also "undo" button, the operator can always return to correct the error, but also repeat the exercise.4. Surgical design and Virtual surgery for femur fractureAccording to the design of the surgical approach, all operations take the appropriate operation plan. In the femur fracture surgery system, the virtual the proximal femur with dynamic hip screw surgery surgical procedure, LISS plate surgery and retrograde intramedullary nailing. In the FreeForm Modeling System, create a virtual surgery environment with a strong sense of immersion, interaction and force feedback functionality. PHANTOM force feedback device controlle the surgical instruments to simulate the process of fixation of the entire operation; surgical process visualization; actual surgical procedure, and can have "power" feel.Explore the virtual surgery in fracture treatment of the general process and key issues, the establishment of three-dimensional model of some orthopedic equipment library and three-dimensional model of fracture. We established a orthopedic virtual surgery process, assessed the advantages and disadvantages of clinical application of virtual surgical.Conclusions1. We can use self-developed medical image processing system Mimics10.0, input CT sequence image to generate three-dimensional model of the many links on quality control, two-dimensional images can be edited and morphological operations, can be three-dimensional reconstruction by setting the parameters of control model reconstruction quality, direct two-dimensional image in three-dimensional view, edit, set the optimal parameter optimization model grid, which was smooth and precise anatomic structure of three-dimensional model. Three-dimensional visualization of the femur model for clinical doctors to provide accurate three-dimensional structural information will help the disease diagnosis and correct assessment of the disease. Three-dimensional visualization of the femur as a medical model of human anatomy teaching tools. In this study, three-dimensional graphics based on three-dimensional reconstruction of fracture model can output a variety of three-dimensional software, a common format for subsequent computer-aided design, finite element analysis, virtual reality and computer-aided surgical plan of use.2. The femur fracture surgery simulation training system is very similar to real surgery environment. In the virtual surgery environment, the operator can manipulate internal fixation device for cutting, drilling, insertion and suturing of the simulation training, with a strong sense of reality, immersion and presence. Young and less experienced orthopedic surgeon can be train orthopedic surgical skills. Orthopedic technology can be a virtual simulation training.3. In the femur fracture surgery simulation operating system, we can plan the fracture surgery preoperative and virtual surgery. Surgical planning can establish the best surgical approach, reduce bleeding and surgical trauma; we can get before and after fracture reduction of the fracture fragment position, size, flip angle and the fracture line to contribute to a better fracture reduction; help in developing strategies and surgical treatment, early selection of suitable fixation devices, specifically the length of implant direction. Repeated before surgery virtual surgery training allows surgery with more skill, greatly reducing the operative time and improve the success rate of surgery, reduce complications, teaching anatomy and surgical training to provide a platform, and can serve as a bridge between Doctors and Patients. |
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