[Development of the personalized finite element model of the adolescent idiopathic scoliosis and its significance].

This study was aimed to develop the personalized finite element model (FEM) of spine of a scoliotic adolescent. We derived the data of spine of a scoliotic adolescent using spiral computed tomography. Then by using a series of computer aided design (CAD) software, the patient-specific 3D finite element model of spine of a scoliotic adolescent was developed.

[A method for extracting landmark geometric data from X-ray images].

Extracting landmark geometric data in C-arm X-ray images is a key technique of camera calibration process in a fluoroscopic-image-based surgical navigation system. The geometric data is the basis of X-ray image distortion correction and C-arm camera calibration. In this paper we present an integrated clustering algorithm for landmark geometric data extraction.

[Current progress of fabricating tissue engineering scaffold using rapid prototyping techniques].

As one of the key factors for tissue engineering, scaffolds affect the spread and proliferation of seeded cells and the formation of new tissue. Although conventional methods can produce porous scaffolds with different porosities, they are lack controls the porous structures of the scaffolds. In recent years, rapid prototyping (RP) techniques have been developed and have successfully applied to fabricate TE scaffolds.

[Application of computer assisted navigation in the treatment of temporomandibular joint ankylosis].

Purpose: The aim of this study is to evaluate the effect of image-guided navigation on gap arthroplasty in the treatment of temporomandibular joint (TMJ) ankylosis.

Methods: Four patients with unilateral TMJ ankylosis underwent gap arthroplasty with the guide of computer-assisted navigation. With preoperative planning and 3-dimensional simulation, normal anatomical structures of the TMJ were created by superimposing and comparing the unaffected and the affected side.

Image guided oral implantology and its application in the placement of zygoma implants.

The application of zygoma implants proposes a successful treatment for functional reconstruction of maxillary defects. However, the placement of zygoma implants is not without risk due to anatomically complex operation sites. Aiming at minimizing the risks and improving the precision of the surgery, an image guided oral implantology system (IGOIS) is presented in this study to transfer the preoperative plan accurately to the operating theatre.

Real-time motion tracking in image-guided oral implantology.

Background: As a crucial part of an image-guided oral implantology system (IGOIS), intra-operative motion tracking is important in terms of accuracy and efficiency. The tracking method, including the relevant algorithms, is described in detail.

Methods: The conventional CAD method is proposed to build the three-dimensional (3D) surgical instrument models.

[An improved design of calibration target used in C-arm-based surgical navigation system].

Seeing that there are several defects in the calibration target currently used in C-arm-based surgical navigation system, we propose an improved design of calibration target based on the theory of generalized mapping. The method of design is introduced, the analysis is made, and the results are reported. The newly designed calibration target is of low manufacturing difficulty and cost; with the new calibration target, the running efficiency and the image quality of the whole navigation system could be improved.

Biomechanical analysis of rapid maxillary expansion in the UCLP patient.

This study was designed to investigate the biomechanical effects of rapid maxillary expansion (RME) in the patient with unilateral cleft lip and palate (UCLP). A finite element model of a patient's craniofacial complex with UCLP was created using data from spiral computed tomographic (CT) scanning. A transversal displacement with a magnitude of 5mm was applied on the maxillary premolar and first permanent molar crown of the model simulating the clinical situation.

[Biomechanical evaluation of zygomatic implant in unilateral maxillary defect restoration].

Purpose: To establish a standardized and modularized finite element model of a normal human skull to simulate the unilateral defect pattern of the maxilla and the stress distribution of craniofacial skeleton with repair subject to the bite force, and to make biomechanical evaluation and functional design of the unilateral maxillary reconstruction method using the microsurgery bone graft and zygomatic implant.

Methods: Based on CT scan and image process technology, a modularized geometrical and finite element model of the human skull was built to simulate unilateral defect pattern of the maxilla and design of the position, direction, length of the zygoma fixture, and the number of the conventional fixtures. Biomechanical properties of the design were evaluated using finite element analysis (FEA) method.

[Research on the development of image guided oral implant system].

In this paper is introduced an image guided oral implant system (IGOIS), including the 3D surface-model generation through Marching Cubes algorithm and large-scale triangular mesh simplification, the realization of pre-operative planning module with computer graphics and image processing technology, the non-invasive point-to-point registration with the fabrication of tooth-supported polymer resin templates and ICP algorithm, and the development of the real-time navigation system software by programming in VTK and VC+ +6.0. The experimental test for a patient's rapid prototype model shows that with the support of IGOIS, the precision achieved in the planning phase can be transferred to the patient so that the accuracy of the oral implant surgery under difficult conditions is improved.

[Effects of ligaments and plantar fascia on the foot finite element analysis].

Some 3D finite element systemic models are currently established and used to simulate the foot biomechanical state. However, during most of these 3D foot finite element static analyses, ligaments and plantar fascia are generally defined by connecting the corresponding attachment points on the bones, and the spaces between the bones are fused together by solid elements with given cartilage stiffness to simulate the connection of bones. This "connection of bones" takes the place of the real interactions between neighbored bones and enhances the structure of foot, which possibly leads to the result that the effects of ligaments and other soft tissues are completely replaced by the effect of articular cartilages.

[Correlation of imaging-based staging to prognosis of nasopharyngeal carcinoma: computed tomography versus magnetic resonance imaging].

Background & Objective: Imaging results are important for clinical staging and irradiation target planning of nasopharyngeal carcinoma (NPC). This study tried to analyze the correlations of staging based on computed tomography (CT) and magnetic resonance imaging (MRI) before radiotherapy to prognosis of NPC.

Methods: Clinical data of 445 pathologically confirmed NPC patients with no metastasis were analyzed.

[Three-dimensional reconstruction of temporomandibular joint with CT and MRI medical image fusion technology].

Objective: To investigate the method of the three-dimensional reconstruction of temporomandibular joint (TMJ) on the basis of CT and MRI medical image fusion technology, which establishes good foundation for a series biomechanical studies and clinical analysis.

Methods: The geometric data for the TMJ model were obtained from a young and healthy male volunteer. Twelve spherical markers were located on the regions of both TMJ and mental tubercles, where CT and MRI scans can reach.

[Bionic design of articular cartilage].

Natural articular cartilage is well known as a special connective tissue with multiple effects and functions, which are important and irreplaceable, in human synovial joints. Biomedical, histological and pathological characteristics of articular cartilage, as well as biomaterial, biomechanical and bio-tribological properties thereof, are summarized from a novel aspect of bionics. Bionic design of articualr cartilage at macro-level and micro-level is carried out from three aspects, i.

[Design and biomechanical evaluation of obturator prostheses with removable partial denture].

The closed palate and obturator prostheses with bar clasp and attachment retention were designed and modeled for repairing the unilateral defect maxillary, and then they were analyzed using finite element method. Under simulated muscle restriction and masticating force boundary, the strength of four maxillary prostheses, the attachment, base plate, bar clasp, denture, obturator et cetera, were considered, and the stress dimension and tendency of the rest living teeth and prostheses were studied. According to the studies on stress, the optimized structure and biomechanical evaluation have a role in the repairs to maxillary defect.

[Digital medicine and computer-aided surgery].

Digital medicine is an important development of the modern medicine and the computer-aided surgery is an important part of the digital medicine. Applications of digital techniques in the computer aided preoperative planning are elucidated in the paper. Techniques of computer-aided design and computer aided manufacture have been widely used in the fields of customized prosthesis replacement, design and manufacture of customized surgical tools and medical auxiliary instruments and here some clinical cases are introduced.

A method based on moving least squares for XRII image distortion correction.

This paper presents a novel integrated method to correct geometric distortions of XRII (x-ray image intensifier) images. The method has been compared, in terms of mean-squared residual error measured at control and intermediate points, with two traditional local methods and a traditional global methods. The proposed method is based on the methods of moving least squares (MLS) and polynomial fitting.

[A mathematical model of 3-dimensional excursive movement of the mandible on Hanau articulator].

Aiming at filling the vacancy in the study about mandibular movement, which mainly focuses on the field of biology at present, this study builds a mathematical model of 3-dimensional excursive movement of the mandible on Hanau articulator from the viewpoint of spatial mechanisms and analytical geometry. On the basis of the theory of spatial mechanisms, the freedom of motion of Hanau articulator is analyzed, and a hypothesis of constraints is presented, the objective of which is to restrict the mandibular movement. Based on the theory of analytical geometry, a series of mathematical expressions are derived to describe the 3-dimensional movement of the mandible mounted on the articulator.

[A three-dimensional analysis of measuring occlusal contacts of complete denture].

Purpose: This study was designed to analyze the complete denture occlusal contacts by three-dimensional digital technique.

Methods: The artificial teeth occlusal surfaces of ten complete dentures were scanned by noncontact laser scanner and were reconstructed by three-dimensional technique. The locations and the numbers of occlusal contacts between the upper and lower full dentures were studied and measured in centric occlusal position, and further compared with the T-Scan system results by paired t test.

[Three-dimensional simulation of protrusive movement for complete denture on articulator].

Purpose: This study was designed to investigate an algorithm model, which can simulate the protrusive movement for complete denture on articulator.

Methods: A typical edentulous case with one-year complete denture was selected for this study. A new complete denture remounted on articulator Hanau H2 was scanned and reconstructed by three-dimensional technique.

[Prognosis analysis of nasopharyngeal carcinoma patients with distant metastasis].

Background & Objective: The incidence of distant metastasis is high in nasopharyngeal carcinoma (NPC). It is the most important cause of death for NPC patients. This study was to investigate prognostic factors of NPC patients with distant metastasis.

A computer-aided oral implantology system.

In order to optimize the position of oral implants and make the best possible use of the available bone volume in the oral implant therapy, a computer-aided oral implantology system including the framework, modeling, preoperative 3D planning, registration method, optical tracking systems and real-time navigation is introduced in this study. With the support of this system, the precision achieved in the planning phase can be transferred to the patient so that the accuracy of the oral implant surgery is improved.

Primary analysis of the first ray using a 3-dimension finite element foot model.

A three-dimensional accurate foot model including bones, cartilages, ligaments and tendons was developed from 3D reconstruction of CT images. The model was used to analyze stress-strain of the joint between the first metatarsal and the medial cuneiform and to study the relationship of the range of motion of the first ray and hallux valgus.

A novel method for creating a 2-d parameterized finite element model of the human femur with matching artificial hip joint based on x-ray image.

There is a novel method for creating a 2-d parameterized finite element model of the human femur with matching artificial hip joint based on X-ray image before the hip joint replacement surgery. It can help us to evaluate the selected appropriate hip joint prosthesis.

Proposal for Conceptual designing of An Innovative C-arm Calibration Target.

In the existing fluoroscopic-image-based orthopedic surgical navigation system, C-arm calibration target has several shortcomings. In order to overcome these shortcomings, an innovative conceptual design for calibration target is proposed. If the redesigned calibration target can be materialized and substituted for the existing one, and relevant software can be adapted accordingly, performance of surgical navigation system is hopefully to be promoted, and development-running cost be decreased.