A 3D deformable surface model for segmentation of objects from volumetric data in medical images

Type A Clostridium botulinum, the causative agent of the food poisoning botulism disease, secretes botulinum neurotoxins along with seven neurotoxin associated proteins (NAPs). The function of NAPs has been shown to protect the neurotoxin from acidity, heat, and proteolytic attack in the environmental and gastrointestinal tract during the toxicogenesis of the botulism disease. One of the NAPs, purified from type A botulinum neurotoxin complex, showed hemagglutination activity. A direct interaction has been demonstrated between purified NAP, a 33-kDa hemagglutinin or Hn-33, and the neurotoxin by using Sephadex G-200 column chromatography. Furthermore, Hn-33 has complete resistance against proteolytic attack at pH 2.0 as well as at normal physiological pH. We have investigated digestion of the neurotoxin in the presence and absence of Hn-33. The neurotoxin alone has been found to be more susceptible to the enzymatic digestion than neurotoxin with Hn-33. The presence of Hn-33 changes the proteolytic fragmentation pattern of the neurotoxin. It seems that Hn-33 protects the neurotoxin from proteolysis either by structural modification of the neurotoxin or by blocking the protease accessible sites of the neurotoxin.     

高炉炉缸三维侵蚀形状的可视化技术

首先采用二维传热模型和神经网络模型,根据现场采集的炉缸热电偶数据,用VC 编程计算出高炉炉缸6个典型轴向剖面各个节点的温度,再以每个剖面的节点温度为基础,采用切片合成法构造更多的空间散乱节点,用Matlab编程,采用三维插值法求出整个高炉炉缸任何一点的温度。取出高炉炉缸内温度为1150℃的空间等温节点作为控制点,绘制双三次Bernstein B啨zier(B B)三角光滑插值曲面,此光滑曲面即为炉缸侵蚀形状。通过Matlab与VC 的混合编程,开发出具有良好的用户界面、强大数据处理能力的应用软件,实现了炉缸炉底三维侵蚀形状的可视化。所开发的软件已经纳入高炉专家系统软件中,丰富了高炉专家系统功能。     

基于Web3D技术的矿床三维可视化系统及应用

基于Web3D技术,研究了在B/S环境下实现矿床三维可视化的方法.通过建立矿床地质数据库及对原始数据的预处理、坐标计算及插值处理,在所建立的系统软件、硬件总体架构之下,实现了Web环境下矿床的整体显示、分层显示、剖切显示和品位区间显示.结合某金矿的实际数据对该系统进行了验证,表明了系统的可靠性及准确性.     

三维可视化技术在矿山开采设计中的应用

在矿山开采设计中,科学合理的应用三维可视化技术,可实现数字化矿山、虚拟化矿山管理。本文结合实际案例,在简要阐述三维可视化技术相关概述的基础上,分析了该技术在矿山开采设计中的具体应用,希望对构建数字化、智慧化矿山管理体系有一定参考价值。     

冶金模具三维可视化及其模型检测

目前,利用计算机视觉和近景摄影测量的理论和方法对冶金模具进行三维可视化和模型检测是一个重要的研究热点.冶金模具的表面一般光滑连续,灰度分布均匀,缺乏可用于匹配的纹理特征.本文针对冶金模具的表面纹理缺乏的特点,在传统用数码相机摄取影像数据的基础上,引入了投影器设备.投影器能够人为地给冶金模具表面添加纹理特征,这些纹理特征清晰稳定,相对容易提取和匹配,成功地解决了纹理缺乏的困难.利用投影器的虚拟影像和数码相机拍摄的带有投影纹理特征的目标物体影像构成立体像对,通过空间前方交会的方法解算纹理特征的空间坐标.连接相邻的空间纹理特征点,形成冶金模具的三维立体模型.直接对三维模型进行测量,能够得到相关的数据参数.根据模型测量数据与冶金模具的设计数据进行比较分析,得到相应的模型检测结果,模型检测的精度能够达到0.2～0.4 mm.整个方法快速、有效,全自动采集各种数据和进行处理,且无破坏性,是非接触式的,几乎不受时空的影响,适应性很强.实验及其结果证明基于投影器的冶金模具三维可视化与模型检测的有效性、正确性和实用性.     

Image guidance of breast cancer surgery using 3-D ultrasound images and augmented reality visualization

This paper describes augmented reality visualization for the guidance of breast-conservative cancer surgery using ultrasonic images acquired in the operating room just before surgical resection. By combining an optical three-dimensional (3-D) position sensor, the position and orientation of each ultrasonic cross section are precisely measured to reconstruct geometrically accurate 3-D tumor models from the acquired ultrasonic images. Similarly, the 3-D position and orientation of a video camera are obtained to integrate video and ultrasonic images in a geometrically accurate manner. Superimposing the 3-D tumor models onto live video images of the patient's breast enables the surgeon to perceive the exact 3-D position of the tumor, including irregular cancer invasions which cannot be perceived by touch, as if it were visible through the breast skin. Using the resultant visualization, the surgeon can determine the region for surgical resection in a more objective and accurate manner, thereby minimizing the risk of a relapse and maximizing breast conservation. The system was shown to be effective in experiments using phantom and clinical data.     

A cryptologic based trust center for medical images

OBJECTIVE: To investigate practical solutions that can integrate cryptographic techniques and picture archiving and communication systems (PACS) to improve the security of medical images. DESIGN: The PACS at the University of California San Francisco Medical Center consolidate images and associated data from various scanners into a centralized data archive and transmit them to remote display stations for review and consultation purposes. The purpose of this study is to investigate the model of a digital trust center that integrates cryptographic algorithms and protocols seamlessly into such a digital radiology environment to improve the security of medical images. MEASUREMENTS: The timing performance of encryption, decryption, and transmission of the cryptographic protocols over 81 volumetric PACS datasets has been measured. Lossless data compression is also applied before the encryption. The transmission performance is measured against three types of networks of different bandwidths: narrow-band Integrated Services Digital Network, Ethernet, and OC-3c Asynchronous Transfer Mode. RESULTS: The proposed digital trust center provides a cryptosystem solution to protect the confidentiality and to determine the authenticity of digital images in hospitals. The results of this study indicate that diagnostic images such as x-rays and magnetic resonance images could be routinely encrypted in PACS. However, applying encryption in teleradiology and PACS is a tradeoff between communications performance and security measures. CONCLUSION: Many people are uncertain about how to integrate cryptographic algorithms coherently into existing operations of the clinical enterprise. This paper describes a centralized cryptosystem architecture to ensure image data authenticity in a digital radiology department. The system performance has been evaluated in a hospital-integrated PACS environment.     

Graphical 3D medical image registration and quantification

We present a graphical three-dimensional method that facilitates image registration and fusion, and provides quantitative geometric and volume information. In particular it enhances the use of functional (radiopharmaceutical) imaging (SPECT, PET) which, though a powerful clinical tool, has the disadvantage of low spatial resolution and ill-defined boundaries. Registration between functional images and structural images (MRI, CT) can augment the anatomical context of these functional images.     

3D reconstruction of tomographic images applied to largely spaced slices

This paper presents a full reconstruction process of magnetic resonance images. The first step is to bring the acquired data from the frequency domain, using a Fast Fourier Transform algorithm. A Tomographic Image Interpolation is then used to transform a sequence of tomographic slices in an isotropic volume data set, a process also called 3D Reconstruction. This work describes an automatic method whose interpolation stage is based on a previous matching stage using Delaunay Triangulation. The reconstruction approach uses an extrapolation procedure that permits appropriate treatment of the boundaries of the object under analysis.     

采空区三维激光扫描信息可视化集成系统设计及应用

为了更好地对采空区三维数据进行有效建模分析,开展采空区三维激光扫描信息可视化集成系统研发.在核心算法的基础上对点云进行过滤分析处理,保证建模的精度和速度.采用CVIS这一专门用于采空区三维激光扫描空间信息处理的系统,Windows开发平台,Visual C++开发环境,以及OpenGL开放性接口进行开发.通过对研发的系...     

基于B/S模式的矿井及典型灾害仿真系统框架与原型

针对数字矿山的发展与建设需要,以面向对象的思想,设计了一个基于Web的矿井及典型灾害三维仿真系统的框架结构.该系统框架包括核心功能模块、数据管理模块和辅助模块等三个功能模块.基于Web技术和可视化技术,形成了一套面向浏览器/服务器(B/S)模式的矿井及典型灾害三维仿真系统实现技术.运用这些技术,通过对某金矿实际数据的采集和处理,实现了基于B/S模式的地表地形、矿体及井巷工程仿真.     

Recovery of 3D volume from 2-tone images of novel objects

In 2-tone images (e.g., Dallenbach's cow), only two levels of brightness are used to convey image structure-dark object regions and shadows are turned to black and light regions are light regions are turned white. Despite a lack of shading, hue and texture information, many 2-tone images of familiar objects and scenes are accurately interpreted, even by naive observers. Objects frequently appear fully volumetric and are distinct from their shadows. If perceptual interpretation of 2-tone images is accomplished via bottom-up processes on the basis of geometrical structure projected to the image (e.g., volumetric parts, contour and junction information) novel objects should appear volumetric as readily as their familiar counterparts. We demonstrate that accurate volumetric representations are rarely extracted from 2-tone images of novel objects, even when these objects are constructed from volumetric primitives such as generalized cones (Marr, D., Nishihara, H.K., 1978. Proceedings of the Royal Society London 200, 269-294; Biederman, I. 1985. Computer Vision, Graphics, and Image Processing 32, 29-73), or from the rearranged components of a familiar object which is itself recognizable as a 2-tone image. Even familiar volumes such as canonical bricks and cylinders require scenes with redundant structure (e.g., rows of cylinders) or explicit lighting (a lamp in the image) for recovery of global volumetric shape. We conclude that 2-tone image perception is not mediated by bottom-up extraction of geometrical features such as junctions or volumetric parts, but may rely on previously stored representations in memory and a model of the illumination of the scene. The success of this top-down strategy implies it is available for general object recognition in natural scenes.     

Strategies for 3-D visualization of ocular structures

Bacteriochlorin a (BCA), a new photosensitizer for photodynamic therapy, was labelled with 99mTc-pertechnetate following a method for the irreversible coupling of 99mTc-pertechnetate to proteins. Biodistribution studies were conducted in male Syrian Golden hamsters with hamster Greene melanoma implanted s.c. on both sides of the abdomen. After i.v. administration of 99mTc-pertechnetate-labelled BCA 17 tissue and fluid samples were analysed at time intervals ranging from 1 to 24 h. Technetium-labelled BCA showed a pronounced affinity for tissues belonging to the reticuloendothelial system. Peak activities, 1 h post-injection, were distributed as follows: lung, liver, spleen, urine > small intestine, kidney, blood, heart, stomach, large intestine > thyroid, tumour, bone, skin, muscle, eye > brain. It is concluded that the technetium-labelled photosensitizer BCA does not accumulate selectively in neoplastic tissue.     

A review of compression methods for medical images in PACS

As an introduction to Section C2 (medical imaging) of track C (Images and PACS) of MIE '97, an appropriate and timely topic concerns the coding for the transmission of medical images in PACS. Speed limitations of existing networks along with the explosive growth of image modalities with extremely high volume outputs have combined to make the issue of medical image coding one of the key considerations in the design of future PACS systems. Both lossless and lossy compression schemes are reviewed and compared, and the compression demands are presented of the main digital medical image modalities.     

A reproducible method for automated extraction of brain volumes from 3D human head MR images

PURPOSE: To assess the frequency and prognosis of skin recurrences after breast-conserving therapy (BCT) compared with other breast recurrences. MATERIALS AND METHODS: From 1968 to 1986, 1,624 patients with unilateral stage I or II breast cancer treated with BCT at the Joint Center for Radiation Therapy (Boston, MA) underwent gross tumor excision and received a dose of > or = 60 Gy to the tumor bed. Skin recurrences (SR) were defined as breast recurrences without associated parenchymal disease. An invasive breast recurrence with any parenchymal disease noted clinically or radiographically was scored as an other breast recurrence (OBR). Median follow-up for survivors was 137 months. RESULTS: SR represented 8% (18 of 229) of all breast recurrences and occurred in 1.1% of all patients. The outcome after local recurrence was different for patients with SR and invasive OBR. Patients with SR more frequently had uncontrolled local failure (50%; 9 of 18) than did patients with OBR (14%; 26 of 188) (P = .0007). Forty-four percent (8 of 18) of patients with SR had distant metastasis simultaneously or within 2 months of the recurrence compared with 5% (9 of 188) of invasive OBR patients (P < .0001). For patients without distant metastasis at the time of recurrence, the 5-year actuarial rate of development of distant metastasis was 60% for SR patients compared with 39% for invasive OBR patients (P = .07), and the corresponding 5-year actuarial survival rates beyond the time of local failure were 51% and 79%, respectively (P = .06). CONCLUSION: In contrast to other types of invasive breast recurrence after breast-conserving therapy, skin recurrences are rare and are associated with a significantly higher rate of distant metastasis and uncontrolled local disease as well as a lower rate of survival.     

Morphologic image processing operators: reduction of partial volume effects for improved 3D visualization of CT data

AIM: The quality of segmentation and three-dimensional reconstruction of anatomical structures in tomographic slices is often impaired by disturbances due to partial volume effects (PVE). The potential for artefact reduction by use of the morphological image processing operators (MO) erosion and dilation is investigated. DESIGN: The CT examinations of 31 patients with pathological alterations in lung or brain were segmented using automatic region growing and the MO were applied in a different number of iterations. The processed regions were 3D-reconstructed (shaded surface display, MIP, volume rendering) and the occurrence of PVE-related artefacts using the signal-to-background ratio (SBR) prior to and after MO application was compared. RESULTS: For all patients under review, the artefacts caused by PVE were significantly reduced by erosion (lung: mean SBRpre = 1.67, SBRpost = 4.83; brain: SBRpre = 1.06, SBRpost = 1.29) even with only a small number of iterations. Region dilation was applied to integrate further structures (e.g. at tumor borders) into a configurable neighbourhood for segmentation and quantitative analysis. CONCLUSIONS: The MO represent an efficient approach for the reduction of PVE artefacts in 3D-CT reconstructions and allow optimized visualization of individual objects.     

三维可视化物探技术在矿山地质勘查中的应用研究

针对传统地质勘查方法具有较高的一致性误差,这次利用钻探技术采集矿山地质三维数据,将数据进行文件转换,同时矫正不合理数据,将处理后的数据以表格的形式进行统一存储,并且采用GeoIPAS V3.2软件对数据进行网格化,形成矿山三维可视化模型,清晰的表现出矿山地质情况,以此实现三维可视化物探技术在矿山地质勘查中的应用。经试验证明,此次提出的方法平均一致性误差为±0.01,远远低于传统方法,满足矿山地质勘查要求。