An adaptive gating approach for X-ray dose reduction during cardiac interventional procedures

The increasing number of cardiac interventional procedures has resulted in a tremendous increase in the absorbed X-ray dose by radiologists as well as patients. A new method is presented for X-ray dose reduction which utilizes adaptive tube pulse-rate scheduling in pulsed fluoroscopic systems. In current pulsed systems, the X-ray tube is pulsed at a fixed rate of 30 pulses/sec (or higher) and an image is formed at the end of each pulse. In the proposed system, pulse-rate scheduling depends on the heart muscle activity phase determined through continuous guided segmentation of the patient's electrocardiogram (ECG). Displaying images generated at the proposed adaptive nonuniform rate is visually unacceptable; therefore, a frame-filling approach is devised to ensure a 30 frame/sec display rate. The authors adopted two approaches for the frame-filling portion of the system depending on the imaging mode used in the procedure. During cine-mode imaging (high X-ray dose), collected image frame-to-frame pixel motion is estimated using a pel-recursive algorithm followed by motion-based pixel interpolation to estimate the frames necessary to increase the rate to 30 frames/sec. The other frame-filling approach is adopted during fluoro-mode imaging (low X-ray dose), characterized by low signal-to-noise ratio images. This approach consists of simply holding the last collected frame for as many frames as necessary to maintain the real-time display rate. Results of simulated system performance on an image sequence from a diagnostic study of left ventricular volume produced an average of approximately 3:1 dose reduction without compromising the diagnostic quality of the generated images. The adaptive pulsed-progressive system concept is viewed as the next evolutionary step in X-ray fluoroscopic systems.     

Collaborative work during interventional radiological procedures based on a multicast satellite-terrestrial network.

Collaboration is a key requirement in several contemporary interventional radiology procedures (IRPs). This work proposes a multicast hybrid satellite system capable of supporting advanced IRP collaboration, and evaluates its feasibility and applicability. Following a detailed IRP requirements study, we have developed a system which supports IRP collaboration through the employment of a hybrid satellite-terrestrial network, a prototype multicast version of wavelet based interactive communication system (WinVicos) application, and a partition aggregation and conditional coding (PACC) wavelet codec. A semistructured questionnaire was also used to receive evaluative feedback from collaborating participants. The departments of interventional radiology of University Hospital of Patras, Greece and of Charite Hospital of Berlin, Germany have been connected on the system. Eight interventional radiologists and a vascular surgeon participated periodically in three satellite-terrestrial "fully collaborative" IRPs (average time 90 min) of high complexity and in four terrestrial educational sessions with great success, evidenced by considerable improving the IRP outcomes (clinical and educational). In case of high complexity, where the simultaneous presence of remote interventional expert and/or surgeon is required, advanced collaboration among staff of geographically dispersed international centers is feasible via integration of existing networking and other technologies.     

精确定点环境信息探测的可移动装置设计

近几年来,人们对环境信息的要求越来越多,单一的温度信息已无法满足人们的需求。根据现有方案的不足,文中设计分析了一种利用可遥控的智能小车来精确定点探测环境信息的设计。设计以单片机STC89C52为核心部件,通过单片机、GPS探测模块和温、湿度检测模块之间的无线通讯,实现对定点环境信息的获取。操作简便,有良好的人机交互界面。     

位置信息约束的SMT料盘X射线图像检测方法

SMT封装物料盘的X射线透视图像发生局部粘连,导致分割准确性降低影响物料的检测与计数统计。提出了基于位置信息约束的分割检测方法,利用器件位置信息对分割区域进行约束提高分割与检测的准确率。首先依据元器件呈螺旋状排列规则,拟合物料盘中心点并计算最内环排列中起点器件位置信息;然后基于中心点与各元器件的位置约束模型,进行法向位置信息与先验位置信息双重约束,对目标器件所在区域进行限定;最后划分分割界限,完成对粘连目标的分割和对元器件的检测与统计。实验结果表明:该方法能够提高物料盘X射线透视图像粘连区域分割与检测的准确率,在有效像元素9 216 pixel,细节解析度110 1p/cm成像环境之下,对不同规格物料盘进行实测,检测误差率控制在0.15%之内。     

Methods for measuring small displacements of television images

Various techniques are described to measure, small displacements of television images. If two successive video frames are considered, their differences are approximately a linear combination of the components of the displacement of the object. If all the points of the frame undergo the same movement, then the velocity estimation problem is solved using linear estimation. However, if some points belong to the moving object and the others to the background, the problem can be stated in the same way only if an algorithm is available to segment the image into fixed and moving areas. Afterwards, linear estimation can be applied to the moving area only. In this paper a segmentation algorithm is proposed which uses dynamic programming (Viterbi algorithm with three states). A more complex situation arises when the points belonging to the moving area are subjected to different movements. The problem can be solved once more using dynamic programming if the displacement components are quantized into(2M + 1) (2M + 1)values, and the number of states of the Viterbi algorithm is augmented to(2M + 1)^{2}. To reduce the technical difficulties of this approach, a simpler method that makes possible the estimation of thenmost probable displacements is proposed. Then the image is segmented into n moving areas with different displacements and a background area using a Viterbi algorithm withn + 1states. Experimental results show that the precision obtainable is about 0.1 pel when the displacements are up to 2-3 pels, the object had approximate dimensions of90 times 90pels, and the signal-to-noise ratio was higher than 33 dB.     

构成“直接读出”温度探头的IC和DMM

对于电子线路的故障排除和调试,图1中的简单温度测量探头可充当一种不可缺的工具。如需测量几个点的温度,可为IC1(Maxim MAX6610)配备一个探头,或者可以永久地将一个或多个器件整合到印制电路板上,或把它们连接到各个元件。电阻器R1、R2、R3把电路的温度定标电压输出设定为各个值(表1)。图2展示了电路在各个温度的代表性输出。     

基于邻域信息的SAR图像变化检测

为了减少合成孔径雷达(SAR)图像中乘性斑点噪声对变化检测结果的影响,充分地利用了像素的邻域信息。首先使用邻域比值(NR)方法构造差异图像,然后提出基于邻域信息的模糊C均值聚类(FCM)算法。NR算子在构造差异图像时能够较好地保留图像信息并抑制噪声的干扰。同时将邻域信息引入到FCM算法的目标函数,以邻域加权距离改进了FCM算法在欧式距离计算中的不足,并约束了隶属度函数,减少了噪声对邻域中心像素的干扰。通过以上考虑像素邻域信息的算法,得到了差异图像的聚类结果,从而实现了SAR图像的变化检测。实验结果表明,所提算法较传统的FCM和K-means聚类算法,可以较好地保留图像变化区域的信息,同时提高了SAR图像变化检测的准确度。     

一种修正平面近场测量中探头位置误差的有效算法

该文提出了一种修正平面近场测量中探头位置误差的算法,并进行了计算机模拟。计算结果表明,所提出的修正算法收敛速度快、数值稳定性好、计算精度高,是一种实用而有效的修正平面近场测量中探头位置误差的方法。     

Methods for digital analysis of AVHRR sea ice images

Algorithms for obtaining information on sea ice conditions from Advanced Very High Resolution Radiometer (AVHRR) digital imagery are presented. These algorithms comprise three steps: discrimination of cloud-covered areas from ice-covered and open water areas, estimation of ice concentration, and measurement of the sizes of ice floes and open water areas (polynyas) within the ice field. For ice-water-cloud discrimination, a dynamic threshold technique is applied to six combinations of the five spectral channels of the AVHRR. This results in an image that is useful for ice analyses. To derive ice concentration estimates, a simple linear relationship between pixel intensity values and amount of ice cover is applied to the visible channel reflectance data. The method for obtaining size frequency distributions is based on a size transform of binary realizations of the ice concentration result and is equally applicable to measuring polynyas and ice floes     

Wall position and thickness estimation from sequences of echocardiographic images

Presents a new method for endocardial (inner) and epicardial (outer) contour estimation from sequences of echocardiographic images. The framework herein introduced is fine-tuned for parasternal short axis views at the papillary muscle level. The underlying model is probabilistic; it captures the relevant features of the image generation physical mechanisms and of the heart morphology. Contour sequences are assumed to be two-dimensional noncausal first-order Markov random processes; each variable has a spatial index and a temporal index. The image pixels are modeled as Rayleigh distributed random variables with means depending on their positions (inside endocardium, between endocardium and pericardium, or outside pericardium). The complete probabilistic model is built under the Bayesian framework. As estimation criterion the maximum a posteriori (MAP) is adopted. To solve the optimization problem, one is led to (joint estimation of contours and distributions' parameters), the authors introduce an algorithm herein named iterative multigrid dynamic programming (IMDP). It is a fully data-driven scheme with no ad-hoc parameters. The method is implemented on an ordinary workstation, leading to computation times compatible with operational use. Experiments with simulated and real images are presented.     

Using edge direction information for measuring blocking artifacts of images

Block-based transform coding is the most popular approach for image and video compression. The objective measurement of blocking artifacts plays an important role in the design, optimization, and assessment of image and video coding systems. This paper presents a new algorithm for measuring blocking artifacts in images and videos. Instead of using the traditional pixel discontinuity along the block boundary, we use the edge directional information of the images. The new algorithm does not need the exact location of the block boundary thus is invariant to the displacement, rotation and scaling of the images. Experiments on various still images and videos show that the new blockiness measure is very efficient in terms of computational complexity and memory usage, and can produce blocking artifacts measurement consistent with subjective rating.     

《信息安全管理体系审核认证机构的要求》标准解读

在分析《信息安全管理体系审核认证机构的要求》标准产生背景的基础上,介绍了标准的结构和主要内容,并重点阐释了原则部分和要求部分。供有关人员在实施和贯彻标准时参考。     

基于邻域统计信息的红外与可见光图像融合

针对红外图像与可见光图像的融合问题,提出了一种基于邻域统计信息的图像融合新算法。首先对图像进行多尺度分解,得到一系列子带系数,然后针对各子带系数的物理特性,提出了高低频规则不同的图像融合算法。对于图像低频部分,首先定义基于邻域统计信息的目标和场景特征参数,然后设计了加权系数自适应变化的加权平均融合策略;对于图像高频部分,首先定义邻域系数分布特征参数,然后设计了受邻域统计信息调制的系数比较取大融合策略。实验结果表明该算法能够很好地将红外图像与可见光图像进行融合,且融合效果优于其他一些算法。     

五维信息同时测量的激光方法

发展同时测量多维信息的激光系统是计量和工业等许多领域普遍提出并有待发展的技术问题。介绍了国内外现有激光五维信息同时测量系统,分析了其优缺点,给出了其发展趋势。     

Methods for engine supervision and control based on cylinderpressure information

The increasing demands for low emissions and low fuel consumption in modern combustion engines require improved methods for online diagnosis and best possible control of the combustion process. It is demonstrated that the cylinder pressure signal can successfully be used for this task. After introduction of some theoretical background, several application examples are presented: an online supervision of fuel injection, some results on feedforward emission control, and a concept for feedback control of spark timing. Experimental results obtained from stock car diesel and spark ignition engines are included to support the automation concepts     

A ghostfree contrast enhancement method for multiview images without depth information

High dynamic range (HDR) images greatly improve visual content quality, but pose challenges in processing, acquisition, and display. Images captured in real-world scenarios with multiple nonlinear cameras, extremely short unknown exposure time, and a shared light source present the additional challenges of incremental baseline and angle deviation amongst the cameras. The disparity maps in such conditions are not reliable; therefore, we propose a method that relies on the accurate detection and matching of feature points across adjacent viewpoints. We determine the exposure gain among the matched feature points in the involved views and design an image restoration method to restore multiview low dynamic range (MVLDR) images for each viewpoint. Finally, the fusion of these restored MVLDR images produces high-quality images for each viewpoint without capturing a series of bracketed exposure. Extensive experiments are conducted in controlled and uncontrolled conditions, and results prove that the proposed method competes for the state-of-the-arts.     

深空通信中结合位置与相位信息的调制方法

随着人类空间探测的距离越来越远, 传统的相移键控(Phase-Shift Keying, PSK)调制信息传输方式面临着发端功率受限、收端解调门限高的挑战.结合远距离光学通信中常用的位置调制, 提出了一种深空通信中基于位置信息的PSK调制方法, 并给出了收发机的实现框图.理论分析与仿真结果均表明, 该调制方法与传统PSK调制相比具有解调门限低的特点, 同等发射功率下, 可为深空通信带来更远的传输距离以及更好的传输质量.     

Proposal for a new tomographic device providing information on the chemical properties of a body section

A system to analyze the chemical properties of a region of tissue located deep inside the human body without having to access it is proposed. The method is based on a high precision detection of X-rays or gamma-rays (photons) from an external source Compton scattered from the tissue under inspection. The method provides chemical information of plane regions lying not too deep inside the body (<6 cm). The amount of radiation absorbed by the body is about the same as needed for a standard X-ray tomography. The exposure time is estimated to be shorter than 10 min.     

基于边缘信息的运动模糊图像的鲁棒盲复原

为获得适用于不同模糊图像且简捷的图像盲复原方法,提出了一种稳健的从单幅模糊图像中求取模糊核并对图像去模糊的图像盲复原方法。根据模糊图像与非模糊图之间的边缘关系求模糊核,并在多尺度框架下针对各个子算法设定自适应参数,从而构建一个稳健的图像盲复原方法。对复原结果用4种无参考的图像质量评价方法的评价结果显示,本文方法在噪声和...