The Monte Carlo code MCML(Monte Carlo modeling of light transport in multi-layered tissue)has been the gold standard for simulations of light transport in multi-layer tissue,but it is ineffective in the presence of th...The Monte Carlo code MCML(Monte Carlo modeling of light transport in multi-layered tissue)has been the gold standard for simulations of light transport in multi-layer tissue,but it is ineffective in the presence of three-dimensional(3D)heterogeneity.New techniques have been attempted to resolve this problem,such as MCLS,which is derived from MCML,and tMCimg,which draws upon image datasets.Nevertheless,these approaches are insufficient because of their low precision or simplistic modeling.We report on the development of a novel model for photon migration in voxelized media(MCVM)with 3D heterogeneity.Voxel crossing detection and refractive-index-unmatched boundaries were considered to improve the precision and eliminate dependence on refractive-index-matched tissue.Using a semi-infinite homogeneous medium,steady-state and time-resolved simulations of MCVM agreed well with MCML,with high precision(∼100%)for the total diffuse reflectance and total fractional absorption compared to those of tMCimg(<70%).Based on a refractive-index-matched heterogeneous skin model,the results of MCVM were found to coincide with those of MCLS.Finally,MCVM was applied to a two-layered sphere with multi-inclusions,which is an example of a 3D heterogeneous media with refractive-index-unmatched boundaries.MCVM provided a reliable model for simulation of photon migration in voxelized 3D heterogeneous media,and it was developed to be a flexible and simple software tool that delivers high-precision results.展开更多
In the field of 3D model matching and retrieval,an effective method for feature extraction is spherical harmonic or its mutations,and is acted on the spherical images.But the obtainment of spherical images from 3D mod...In the field of 3D model matching and retrieval,an effective method for feature extraction is spherical harmonic or its mutations,and is acted on the spherical images.But the obtainment of spherical images from 3D models is very time-consuming,which greatly restrains the responding speed of such systems.In this paper, we propose a quantitative evaluation of the whole process and give a detailed two-sided analysis based on the comparative size between pixels and voxels.The experiments show that the resultant optimized parameters are fit for the practical application and exhibit a satisfactory performance.展开更多
以腧穴解剖研究成果为基础,将临床常用的18个危险穴位的解剖结构数据融入汉堡大学VOXEL-MAN三维数字化虚拟人体中,开发一套VOXEL-MAN 3D Navigator:Acupuncture运行软件(针灸学三维影像浏览器),动态、三维显示腧穴的层次解剖结构和不同...以腧穴解剖研究成果为基础,将临床常用的18个危险穴位的解剖结构数据融入汉堡大学VOXEL-MAN三维数字化虚拟人体中,开发一套VOXEL-MAN 3D Navigator:Acupuncture运行软件(针灸学三维影像浏览器),动态、三维显示腧穴的层次解剖结构和不同角度针刺所经过的断面解剖结构,并建立相关的知识库体系,能够加深对图像内容的理解,有利于提高临床针刺疗效和避免针刺意外事故的发生,并为针灸提供一种理想直观的多媒体教学手段和方法。展开更多
An efficient voxelization algorithm is presented for polygonal models by using the hardware support for the 2 D rasterization algorithm and the GPU programmable function to satisfy the volumetric display system. The v...An efficient voxelization algorithm is presented for polygonal models by using the hardware support for the 2 D rasterization algorithm and the GPU programmable function to satisfy the volumetric display system. The volume is sampled into slices by the rendering hardware and then slices are rasterated into a series of voxels. A composed buffer is used to record encoded voxels of the target volume to reduce the graphic memory requirement. In the algorithm, dynamic vertexes and index buffers are used to improve the voxelization efficiency. Experimental results show that the algorithm is efficient for a true 3-D display system.展开更多
Now the image display techniques have made great progress. The planar display and a fully new true 3-D volumetric display technique are rapidly researched and come into the application. A method based on the voxel mak...Now the image display techniques have made great progress. The planar display and a fully new true 3-D volumetric display technique are rapidly researched and come into the application. A method based on the voxel makes the observer able to get a true 3-D effect freely without any additional facilities. This paper introduces the basic form of the swept-volume display technique and discusses its voxelization process. By the translational motion prototype, this paper emphasizes how to get the voxel mapping matrix. The translated image data are the data of the beam source deflections. Finally the voxel ordering and the optimizing are also discussed.展开更多
The main purpose of this work was to perform a rigorous computational study on scintimammography with a Mura-mask based on Monte Carlo simulation of voxelized breast phantoms. Three main objectives were addressed:(1) ...The main purpose of this work was to perform a rigorous computational study on scintimammography with a Mura-mask based on Monte Carlo simulation of voxelized breast phantoms. Three main objectives were addressed:(1) verification of Geant4 version 10.4,(2)optimization of the imaging setup, and(3) small tumor detection and localization. We successfully verified the Geant4-based imaging of a commonly used phantom in the field. We used a Mura-mask with a 41× 41 array pattern with adjustable thickness, material, and hole shape(box and cylinder);a low-energy high-resolution collimator with different hole shapes(cylinder and hexagon);and a voxelized breast phantom with different sizes(small, medium,and large) and glandularity percentages(low, medium, and high). We also compared the detector crystal outputs of CdZnTe and NaI(Tl). The simulation was followed by a deconvolution procedure, and the data(images) were statistically emphasized. Statistical metrics indicate that the Mura-mask(W material with 1.5 mm thickness and box holes) combined with a CdZnTe detector leads to the optimum point spread function. Finally, a preliminary study on small-sized tumor detection and localization was conducted with different tumor-to-background ratios(from2 to 12). Tumors with diameters of 5 and 8 mm could be detected, while those of 2 mm were undetectable. Nevertheless, this study enhances our understanding of the early detection of tumors in the field of scintimammography.展开更多
With improvements in care of at-risk neonates, more and more children survive. This makes it increasingly important to assess, soon after birth, the prognosis of children with hypoxic-ischemic encephalopathy. Computed...With improvements in care of at-risk neonates, more and more children survive. This makes it increasingly important to assess, soon after birth, the prognosis of children with hypoxic-ischemic encephalopathy. Computed tomography, ultrasound, and conventional magnetic resonance imaging are helpful to diagnose brain injury, but cannot quantify white matter damage. In this study, ten full-term infants without brain injury and twenty-two full-term neonates with hypoxic-ischemic encephalopathy （14 moderate cases and 8 severe cases） underwent diffusion tensor imaging to assess its feasibility in evaluating white matter damage in this condition. Results demonstrated that fractional anisotropy, voxel volume, and number of fiber bundles were different in some brain areas between infants with brain injury and those without brain injury. The correlation between fractional anisotropy values and neonatal behavioral neurological assessment scores was closest in the posterior limbs of the internal capsule. We conclude that diffusion tensor imaging can quantify white matter injury in neonates with hypoxic-ischemic encephalopathy.展开更多
This paper presents a voxel-based region growing method for automatic road surface extraction from mobile laser scanning point clouds in an expressway environment.The proposed method has three major steps:constructing...This paper presents a voxel-based region growing method for automatic road surface extraction from mobile laser scanning point clouds in an expressway environment.The proposed method has three major steps:constructing a voxel model;extracting the road surface points by employing the voxel-based segmentation algorithm;refining the road boundary using the curb-based segmentation algorithm.To evaluate the accuracy of the proposed method,the two-point cloud datasets of two typical test sites in an expressway environment consisting of flat and bumpy surfaces with a high slope were used.The proposed algorithm extracted the road surface successfully with high accuracy.There was an average recall of 99.5%,the precision was 96.3%,and the F1 score was 97.9%.From the extracted road surface,a framework for the estimation of road roughness was proposed.Good agreement was achieved when comparing the results of the road roughness map with the visual image,indicating the feasibility and effectiveness of the proposed framework.展开更多
基金This research was supported by the National Natural Science Foundation of China(Grant No.30727002)the National High-Tech R&D Program of China(2006AA020801)111 project,and the Program for Changjiang Scholars and Innovative Research Team in University.
文摘The Monte Carlo code MCML(Monte Carlo modeling of light transport in multi-layered tissue)has been the gold standard for simulations of light transport in multi-layer tissue,but it is ineffective in the presence of three-dimensional(3D)heterogeneity.New techniques have been attempted to resolve this problem,such as MCLS,which is derived from MCML,and tMCimg,which draws upon image datasets.Nevertheless,these approaches are insufficient because of their low precision or simplistic modeling.We report on the development of a novel model for photon migration in voxelized media(MCVM)with 3D heterogeneity.Voxel crossing detection and refractive-index-unmatched boundaries were considered to improve the precision and eliminate dependence on refractive-index-matched tissue.Using a semi-infinite homogeneous medium,steady-state and time-resolved simulations of MCVM agreed well with MCML,with high precision(∼100%)for the total diffuse reflectance and total fractional absorption compared to those of tMCimg(<70%).Based on a refractive-index-matched heterogeneous skin model,the results of MCVM were found to coincide with those of MCLS.Finally,MCVM was applied to a two-layered sphere with multi-inclusions,which is an example of a 3D heterogeneous media with refractive-index-unmatched boundaries.MCVM provided a reliable model for simulation of photon migration in voxelized 3D heterogeneous media,and it was developed to be a flexible and simple software tool that delivers high-precision results.
基金the National Natural Science Foundation of China(No.60903111)
文摘In the field of 3D model matching and retrieval,an effective method for feature extraction is spherical harmonic or its mutations,and is acted on the spherical images.But the obtainment of spherical images from 3D models is very time-consuming,which greatly restrains the responding speed of such systems.In this paper, we propose a quantitative evaluation of the whole process and give a detailed two-sided analysis based on the comparative size between pixels and voxels.The experiments show that the resultant optimized parameters are fit for the practical application and exhibit a satisfactory performance.
文摘以腧穴解剖研究成果为基础,将临床常用的18个危险穴位的解剖结构数据融入汉堡大学VOXEL-MAN三维数字化虚拟人体中,开发一套VOXEL-MAN 3D Navigator:Acupuncture运行软件(针灸学三维影像浏览器),动态、三维显示腧穴的层次解剖结构和不同角度针刺所经过的断面解剖结构,并建立相关的知识库体系,能够加深对图像内容的理解,有利于提高临床针刺疗效和避免针刺意外事故的发生,并为针灸提供一种理想直观的多媒体教学手段和方法。
文摘An efficient voxelization algorithm is presented for polygonal models by using the hardware support for the 2 D rasterization algorithm and the GPU programmable function to satisfy the volumetric display system. The volume is sampled into slices by the rendering hardware and then slices are rasterated into a series of voxels. A composed buffer is used to record encoded voxels of the target volume to reduce the graphic memory requirement. In the algorithm, dynamic vertexes and index buffers are used to improve the voxelization efficiency. Experimental results show that the algorithm is efficient for a true 3-D display system.
文摘Now the image display techniques have made great progress. The planar display and a fully new true 3-D volumetric display technique are rapidly researched and come into the application. A method based on the voxel makes the observer able to get a true 3-D effect freely without any additional facilities. This paper introduces the basic form of the swept-volume display technique and discusses its voxelization process. By the translational motion prototype, this paper emphasizes how to get the voxel mapping matrix. The translated image data are the data of the beam source deflections. Finally the voxel ordering and the optimizing are also discussed.
基金supported by The National Plan for Science,Technology and Innovation(MAARIFAH)King Abdulaziz City for Science and Technology,Kingdom of Saudi Arabia,Award Number(12-MED2516-02)
文摘The main purpose of this work was to perform a rigorous computational study on scintimammography with a Mura-mask based on Monte Carlo simulation of voxelized breast phantoms. Three main objectives were addressed:(1) verification of Geant4 version 10.4,(2)optimization of the imaging setup, and(3) small tumor detection and localization. We successfully verified the Geant4-based imaging of a commonly used phantom in the field. We used a Mura-mask with a 41× 41 array pattern with adjustable thickness, material, and hole shape(box and cylinder);a low-energy high-resolution collimator with different hole shapes(cylinder and hexagon);and a voxelized breast phantom with different sizes(small, medium,and large) and glandularity percentages(low, medium, and high). We also compared the detector crystal outputs of CdZnTe and NaI(Tl). The simulation was followed by a deconvolution procedure, and the data(images) were statistically emphasized. Statistical metrics indicate that the Mura-mask(W material with 1.5 mm thickness and box holes) combined with a CdZnTe detector leads to the optimum point spread function. Finally, a preliminary study on small-sized tumor detection and localization was conducted with different tumor-to-background ratios(from2 to 12). Tumors with diameters of 5 and 8 mm could be detected, while those of 2 mm were undetectable. Nevertheless, this study enhances our understanding of the early detection of tumors in the field of scintimammography.
基金supported by a grant from the Clinical Medicine Science and Technology Projects in Jiangsu Province of China,No.BL2014037a grant from the Changzhou City Science and Technology Support Plan in China,No.CE20165027+1 种基金a grant from the Changzhou Health Development Planning Commission Major Projects in China,No.ZD201515the Changzhou High-Level Health Personnel Training Project Funding
文摘With improvements in care of at-risk neonates, more and more children survive. This makes it increasingly important to assess, soon after birth, the prognosis of children with hypoxic-ischemic encephalopathy. Computed tomography, ultrasound, and conventional magnetic resonance imaging are helpful to diagnose brain injury, but cannot quantify white matter damage. In this study, ten full-term infants without brain injury and twenty-two full-term neonates with hypoxic-ischemic encephalopathy （14 moderate cases and 8 severe cases） underwent diffusion tensor imaging to assess its feasibility in evaluating white matter damage in this condition. Results demonstrated that fractional anisotropy, voxel volume, and number of fiber bundles were different in some brain areas between infants with brain injury and those without brain injury. The correlation between fractional anisotropy values and neonatal behavioral neurological assessment scores was closest in the posterior limbs of the internal capsule. We conclude that diffusion tensor imaging can quantify white matter injury in neonates with hypoxic-ischemic encephalopathy.
基金Project(SIIT-AUN/SEED-Net-G-S1 Y16/018)supported by the Doctoral Asean University Network ProgramProject supported by the Metropolitan Expressway Co.,Ltd.,Japan+2 种基金Project supported by Elysium Co.Ltd.Project supported by Aero Asahi Corporation,Co.,Ltd.Project supported by the Expressway Authority of Thailand。
文摘This paper presents a voxel-based region growing method for automatic road surface extraction from mobile laser scanning point clouds in an expressway environment.The proposed method has three major steps:constructing a voxel model;extracting the road surface points by employing the voxel-based segmentation algorithm;refining the road boundary using the curb-based segmentation algorithm.To evaluate the accuracy of the proposed method,the two-point cloud datasets of two typical test sites in an expressway environment consisting of flat and bumpy surfaces with a high slope were used.The proposed algorithm extracted the road surface successfully with high accuracy.There was an average recall of 99.5%,the precision was 96.3%,and the F1 score was 97.9%.From the extracted road surface,a framework for the estimation of road roughness was proposed.Good agreement was achieved when comparing the results of the road roughness map with the visual image,indicating the feasibility and effectiveness of the proposed framework.
