Registration for 3D model of human atlas based on vertex information / 医用生物力学

Objective To develop a registration method for 3D human atlas models by using geometric information of the vertices so as to lay a foundation for statistical modeling of atlas. Methods Based on CT images of the normal human, thirty 3D models of human atlases were created and marked by the manual selected points, including 1 standard module, 20 training sets and 9 testing samples. The training sets were first registered with the standard module, including calculation on geometric information of the individual vertex and optimization process of weight coefficients in the registration models. By minimizing the energy function defined with the Euclidean distances between the automatic registered points and the manual selected points in training sets, the optimized weight coefficients could be obtained. The testing samples were then registered with the standard module to calculate the Euclidean distances between the automatic registered points and the manual selected points. The results were then compared with the training sets to evaluate the stability of the registration method. Results The registration function and the corresponding optimized weight coefficients were obtained, and the average errors for the training sets and testing samples were 1.983 mm and 2.045 mm, respectively. Further statistical analysis showed that there were no obvious differences in the error distributions among the training sets and testing samples. Conclusions The accuracy and stability of the proposed registration method meet the requirement in medical applications, and it can provide automatic registration of points of interest on human atlas models and be used for element classification in statistical modeling.

Six degree-of-freedom acquisition and analysis of jaw opening and closing with motion capture system / 南方医科大学学报

<p><b>OBJECTIVE</b>To explore the six degrees of freedom of jaw opening and closing movement with motion capture and analysis system to establish a quantitative method for studying mandibular movement and a digital basis for virtual reality study of mandibular movement.</p><p><b>METHODS</b>In a male adult with normal dentition without temporomandibular joint disorders, 3 fluorescent markers were pasted in the upper dentition and 4 in the lower dentition. Six cameras of the motion capture system were arranged in a semi-circular fashion. The subject sat in front of the camera at an 80-cm distance with the Frankfort plane kept parallel to the horizontal plane. The degree-of-freedom (3 linear displacement and 3 angular displacement) of jaw opening and closing movement was obtained by collecting the marker motion.</p><p><b>RESULTS</b>Six degrees of freedom of jaw opening and closing were obtained using the motion capture system. The maximum linear displacements of X, Y and Z axes were 5.888 089 cm, 0.782 269 cm, and 0.138 931 cm, and the minimum linear displacements were -3.649 83 cm, -35.961 2 cm, -5.818 63 cm, respectively. The maximum angular displacements of X, Y and Z axes were 0.760 088°, 2.803 753°, and 0.786 493°, with the minimum angular displacements of -2.526 18°, -0.625 94°, and -25.429 8°, respectively. Variations of linear displacements during jaw opening and closing occurred mainly in the Y axis, and those of angular displacement occurred mainly in the Z axis.</p><p><b>CONCLUSION</b>The six degree-of-freedom of mandibular movement can be accurately obtained with the motion capture system to allow quantitative examination of the mandibular movement.</p>

Application of three-dimensional laser scanning-based maxillofacial soft tissue reconstruction in orthodontic treatment / 南方医科大学学报

<p><b>OBJECTIVE</b>To establish a convenient and rapid method for constructing a digital model of the maxillofacial soft tissue based on three-dimensional laser surface scanning to allow direct and accurate observation of the soft tissue changes in the course of orthodontic treatment.</p><p><b>METHODS</b>The point cloud data of three-dimensional laser scanning of the maxillofacial region were acquired from a healthy woman with Angle Class I occlusion, who maintained a horizontal Frankfort plane during scanning with the scanner placed at a distance of 80 cm. The scanning was repeated twice after wearing the dental cast for an Angle Class I occlusion. The three-dimensional digital model of the maxillofacial soft tissue was constructed based on the point cloud using GeoMagic10.0 software.</p><p><b>RESULTS</b>The high-resolution three-dimensional model of the maxillofacial soft tissue reconstructed allowed accurate observation of the distinct facial anatomical landmarks and represented directly the soft tissue changes in the process of orthodontic treatment by merging the models. Using the analytic tool provided by the software, this model also allowed direct quantitative measurement of the nasolabial angle and the distances from the esthetic plane to the upper lip, labral inferior, and mentolabial sulcus, which were 111.86°, -3.57 mm, -2.54 mm, and 3.95 mm before orthodontic treatment as compared to 114.31°, -2.73 mm, -1.06 mm, and 3.46 mm during treatment, and 116.53°, -0.15 mm, 0.64 mm, and 3.11 mm after the treatment, respectively.</p><p><b>CONCLUSION</b>Three-dimensional laser surface scanning enables accurate and rapid construction of the digital model of the facial soft tissues, which may provide valuable assistance in orthodontic treatment.</p>

Three-dimensional design of surgery for mandibular retrusion / 南方医科大学学报

<p><b>OBJECTIVE</b>To explore the feasibility of surgical design for mandibular retrusion using three-dimensional software.</p><p><b>METHODS</b>Three-dimensional reconstruction was performed by Mimics software based on the preoperative CT data. The model of the maxillofacial region was imported into Rapidform software for measuring the associated parameters and Geomagic software for simulation of osteotomy. The reliability of the virtual operation was validated during the surgery.</p><p><b>RESULTS</b>The model of mandibular retrusion was reconstructed and successfully used to simulate the surgery. The simulation result was applied in subsequent actual surgery and good surgical outcomes were achieved.</p><p><b>CONCLUSION</b>The three-dimensional software can be used to simulate the surgery for mandibular retrusion and improve the predictability and accuracy of the surgery.</p>

Construction of the digital models of masseter and temporal muscles with three-dimensional laser scanning / 南方医科大学学报

<p><b>OBJECTIVE</b>To explore a new method for establishing digital models of the masseter and temporal muscles and superficial soft tissue using three-dimensional laser scanning technique.</p><p><b>METHODS</b>One adult male cadaveric head without malformation was dissected to expose the superficial portion of the masseter and temporalis. Multiple aspects of the sample were scanned with three-dimensional laser scanning system, and the point clouds of the masseter and temporal muscles were generated. The specimen was scanned again after the masseter and temporal muscles had been removed. The digital model of the muscles was reconstructed with the point clouds using Geomagic software, and the morphology of the muscle model was observed and measured.</p><p><b>RESULTS</b>The 3-D digital models of the masseter and temporal muscles with the anatomical characteristics were reconstructed based on the point clouds using Geomagic 8.0 software.</p><p><b>CONCLUSION</b>The digital model of the muscles can vividly demonstrate the muscle contours, which provides a basis for morphological study and biomechanical analysis of the muscles.</p>

2D/3D registration system based on single X ray image and CT data / 医用生物力学

Objective To build a 2D/3D registration system based on the compute unified device architecture(CUDA) frame with single X-ray image and CT data of knee joints and apply it in the research of knee motion and stability of implanted prosthesis. Method The digital radiography(DR) equipment used in the study was calibrated by the Zhang zhengyou Calibration Method, and then digitally rendered radiographs(DRR) images were generated in the CUDA frame with light tracing algorithm, and the best 2D/3D registration parameters were calculated with a similarity operator of cross correlation; finally, the results were evaluated by using the method of 3D/3D registration with data obtained from a 3D laser scanner. Results With knee specimen X-ray images and CT data, in 6 degrees of freedom, the average errors of transform were below 1 mm, and those of rotation were below 1°. Conclusions The 2D/3D registration system can meet the precision requirement of motion detection and be used to study the knee motion and prosthesis location.

Study on the three dimensional hepatic virtual operation based on the data of 64-slice helical CT scanning / 中华外科杂志

<p><b>OBJECTIVE</b>To study the surgery plan and simulation effect of the three dimensional (3D) hepatic virtual operation based on the data of 64-slice helical CT scanning and to probe the feasibility of the virtual operation based on the FreeForm Modeling System.</p><p><b>METHODS</b>The volunteer liver was scanned to collect two dimensional (2D) DICOM data of 64-slice helical CT scanning and the 3D hepatic and intrahepatic vessels model were reconstructed by MIMICS software. The reconstructed liver, the intrahepatic vessels model and the artificial tumor models were output into the FreeForm Modeling System in the STL format. The device PHANTOM with the characterization of dynamo-feedback was applied to make the operation on the 3D hepatic.</p><p><b>RESULTS</b>The spatial relationship between the tumour and the intrahepatic vessels were clearly observed by rotation and enlargement of the target. According to the operation principle, the left lobe of liver resection was simulated by manipulating the device PHANToM. Through the liver transparence surface, the intrahepatic vessels were easily distinguished. The operation procedure was accord with the clinic hepatic surgery. Meanwhile, during the operation, by adjusting the incision objective intensity, the dynamo-feedback intensity was definitely touched.</p><p><b>CONCLUSIONS</b>By using the FreeForm Modeling System,the hepatic operation procedure can be simulated ahead of time. The operation complication in the practical surgery can be anticipated and the individualization operation schema can be reasonable instituted.</p>

Establishment of a testing system of three-dimensional spinal kinematics in vivo based on two- and three-dimensional image registration / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the feasibility of using two- and three-dimensional (2D/3D) image registration for establishing a testing system of 3D kinematics of the spine in vivo.</p><p><b>METHODS</b>CT data of the adult human lumbar spine were collected and the two orthogonal images of the same specimen were captured using an X-ray fluoroscope at two different positions. The 3D computer models of L3 and L4 vertebrae were reconstructed. A virtual fluoroscope was then created with solid modeling software to reproduce the relative positions of the orthogonal images. Two virtual cameras in the software were used to represent the X-ray sources. The 3D computer models of the L3 and L4 vertebrae were then introduced into the virtual fluoroscope respectively and projected onto the orthogonal images by the two virtual cameras. By matching the projections of the 3D model to the orthogonal images of L3 and L4 vertebrae, the 3D positions of L3 and L4 were obtained. After calculation, the relative displacement and angle of L3 were determined.</p><p><b>RESULTS</b>After 2D/3D image registration, the relative displacement and angle were calculated. Compared with position I, the positional changes of L3 were represented with an extension of 5.86 degrees, left bending of 1.85 degrees and right rotation of 2.96 degrees.</p><p><b>CONCLUSION</b>2D/3D image registration allows the simulation of 3D kinematics of the spine in vivo, but the efficiency and accuracy of this technique need further evaluation.</p>

Method to transfer physiological data through carrier-current communication / 医疗卫生装备

This article describes a method totransfer physiological data through carrier-current communication.The microcontroller measures the data of heartrate and body temperature and sends them through the serial port tothe carrier-current module implementing carrier-current communication.This method can be used totransfer physiological data through short distance less than200meters.