计算机在超声医学图像处理中的应用

介绍了计算机在超声医学图像处理领域的应用,着重讨论了超声医学成像和超声医学图像管理的方法与应用,具体分析了医院医学图像存档及通信系统(PACS)中B超影像工作站的结构与功能。     

数字化医院中的PACS系统定位

在数字化医院中如何定位PACS系统，涉及到建设数字化医院的软硬件架构及未来的应用基础。本文主要描述数字化医院的框架结构，提出数字化医院的管理层面(传统HIS等)和业务层面(PACS、RIS、诊疗工作站等)的研究内容，分析了PACS系统建立过程中的重点，并结合公司研发机构对医学影像应用方面的研究，临床PACS(Clinical-PACS)将是以后PACS建设的方向，提出以影像应用为核心建立Angelplan-eH3MPACS系统的思想，就如何突出和延伸PACS系统中影像资料价值及临床应用价值提出自己的看法。作者认为，PACS系统是建设数字化医院的核心工作之一，也是医院信息系统建设中投资较大的系统，只有具备影像临床应用功能，能为诊疗提供服务，符合国际标准的PACS才能在未来的数字化医院建设中发挥更大的作用，也是数字化医院建设的基础与关键。     

医学影像存档与通信系统存储系统的探讨

由于PACS系统需要一个高性能的存储系统的支撑，本文重点讨论了PACS的存储管理系统方案、PACS对计算机存储体系的要求、如何选择适当的存储架构以及PACS设计原则和分析方法.     

PACS系统在超声影像学临床教学中的应用

超声影像学的临床教学过去主要依赖对超声检查的实时观摩,缺乏丰富多样的图像资料和详细全面的病例资料[1]。随着PACS(P ictures arch iving and Commun ications System)系统的投入使用,这个问题得到明显改善。现就PACS系统在超声影像学临床教学中的应用作一探讨。1提供了丰富多样的高质量影像资料PACS系统及图像存储与传输系统,是应用于医院的数字医疗设备如CT、MR、US、DSA、CR等所产生的数字化医学图像信息的采集、存储、管理、诊断、信息处理的综合应用系统。它以高速计算机设备为基础,以高速网络连接各种影像设备和相关设…     

一种基于B/S模式的PACS的研究与实现

我们采用 B/ S模式及其构建技术 ,给出了一个完整 PACS体系结构的设计方案 ,并介绍了在此体系结构基础上实现的 PACS各部分的功能应用。此 B/ S模式的 PACS具备安全、稳定、易维护、易升级等优点 ,可方便的实现远程医疗     

医学CBIR系统与PACS的集成平台研究

随着在临床中应用的数字影像设备越来越多,CBIR对于PACS变得越来重要。若使强大的算法变得可能,医学CBIR系统必须被整合和集成到PACS中,才能更好地为医生所应用。考虑到医生检索习惯,本文提出了一个基于现有的标准协议把医学CBIR系统整合到PACS中的平台模型,并保证两系统的自主性,为真正实现在PACS中基于内容的检索提供了理论基础和方法指导。     

HL7与DICOM之间数据交换的分析与实现

本文分析了HL7和DICOM共同关心的四种数据信息。进而阐述了通过HL7事务和消息在HIS和PACS之间进行这四种数据信息交换的机制。最后使用面向对象的方法建立了一个HL7-DICOM网关，并且实现了其中两种数据信息的交换。说明了如何构造HL7消息来实现HIS和PACS之间的数据交换。     

PACS系统的Web访问方案设计

本文结合PACS系统的特点,分析了PACS系统Web方式浏览的体系结构和实现模式．确立了一种在B／S模式下用Java Applet技术实现PACS系统的Web访问的设计方案,并给出了实现过程。此方案具有平台独立、稳定、易维护、易升级等优点,对构筑远程医疗系统具有一定的实用价值。     

PACS中的DICOM标准分析及应用

DICOM是PACS系统中被国际认可的医学图像标准。本文分析了DICOM标准的主要部分，特别是信息对象定义、服务类和服务对象、数据组织格式、通讯机制等部分。结合广州医学院附属第二医院的实际情况，阐述了DICOM标准如何在PACS中应用。     

PACS在核医学中的应用研究

PACS在核医学领域可实现资源共享,让各种影像设备和资料有机结合在一起,实现资料和数据的一体化发展,在核医学中有重要的作用。PACS在信息采集、材料分析、和数据处理等方面有重要的作用。本文将以PACS的作用为基本点,对其在核医学中应用进行系统的分析。     

DICOM医学图像的存储与管理

随着数字化医学成像设备在医院的广泛使用,对医学图像及相关数据的存档管理以及在不同科室之间的数据共享的要求越来越迫切,这就需要建立PACS(图像存档和通讯系统),这方面国外已经发展了很多年,我国目前处于起步阶段.本文参照PACS系统的一个已经被国际认可的医学图像标准即医学成像和通讯标准DICOM(digital imaging and communication in medicine),研究了标准的各个部分,特别是兼容性、信息对象定义(IOD)、服务对象对类(SOP)、数据编码等部分,就具体实现PACS系统的一个重要方面即医学图像的存档和管理做了深入的探讨,在此基础上建立了医学图像数据库系统,为实现医学图像信息的网络共享打下了基础.     

高帧率超声成像系统中一种高信噪比扇形成像模式的实现

基于有限衍射波束的高帧率（High frame rate，HFR）成像系统能实现快速成像，但成像区域为矩形，使得远区成像的信息量受到一定的限制；同时由于通过一次发射事件成像，信噪比较低。本文提出一种方案有效地解决了这些问题。方案采用Golay互补序列作为激励信号及两次发射与接收过程，每个发射事件同时发射两个不同角度的平面波。在对接收信号进行处理时。利用Golay互补序列良好的正交性及其相关函数为冲击函数特征，不仅显著地提高了接收信号的信噪比，而且有效地分离出相对于不同发射角度的两个平面波的回波信号。然后分别用HFR成像方法重建不同区域图像，最后合成一帧扇形成像。     

A compression and transmission system of ultrasonic image sequence for telemedicine.

OBJECTIVE: A newly developed compression and transmission system of ultrasound image sequence for telemedicine is proposed for transmitting ultrasonic image sequence in real time via IP-connected computers for telemedicine. MATERIALS AND METHODS: In the compression method, the characteristics of ultrasound images were taken into account. Only sound data were essential, and the histogram of the images had two narrow distributions around black-and-white areas. The sound data, therefore, were run length encoded and then transmitted. In the transmission, UDP/IP was employed with a time weight insertion among the packets so as not to overflow the data buffers of computers in this system to derive the maximum transmission performance up to the network capacity. The decompression method was the same as the generation of the sector scan images from the sound data, so that natural ultrasound image sequence could be obtained. RESULTS: This system was evaluated by transmitting the ultrasonic image sequence of the heart via ISDN (1. 5 mbps). Although this system completely specialized in compression and transmission of the ultrasound sector scan image sequence, a relatively good performance in the frame rate and the image quality was achieved, compared with the previous systems (H.260, JPEG, and MPEG-1).     

Image sampling in static telepathology for frozen section diagnosis

BACKGROUND: A frozen section diagnostic service is often not directly available in small rural or mountain hospitals. In these cases, it could be possible to provide frozen section diagnosis through telepathology systems. Telepathology is based on two main methods: static and dynamic. The former is less expensive, but involves the crucial problem of image sampling. AIMS: To characterise the differences in image sampling for static telepathology when undertaken by pathologists with different experience. METHODS: As a test field, a previously studied telepathology method based on multimedia email was adopted. Using this method, three pathologists with different levels of experience sampled images from 155 routine frozen sections and sent them to a distant pathology institute, where diagnoses were made on digital images. After the telepathology diagnoses, the glass slides of both the frozen sections and the definitive sections were sent to the remote pathologists for review. RESULTS: Four of 155 transmissions were considered inadequate by the remote pathologist. In the remaining 151 cases, the telepathology diagnosis agreed with the gold standard in 146 (96.7%). There was no significant divergence between the three pathologists in their sampling of the images. Each case comprised five images on average, acquired in four minutes. The overall time for transmission was about 19 minutes. CONCLUSIONS: The results suggest that in routine frozen section diagnosis an inexperienced pathologist can sample images sufficiently well to permit remote diagnosis. However, as expected, the internet is too unreliable for such a time dependent task. An improvement in the system would involve integrated real time features, so that there could be interaction between the two pathologists.     

Study of direct and indirect parametric estimation methods of linear models in dynamic positron emission tomography

In dynamic positron emission tomography (PET) studies, the time changing activity of the radiotracer is measured through multiple consecutive frames. Subsequent pixel-by-pixel application of the appropriate kinetic model provides quantitative information in terms of images of the distribution of the physiological parameter of interest. In this context, iterative reconstruction methods may be used to reconstruct for each time frame a static image of appreciable higher quality than the analytical algorithms, especially in low-count cases. Furthermore, if the reconstruction algorithm also models the kinetics of the measured counts, the parametric image is expected to be of even higher quality. In this work, we investigate the methodology to directly reconstruct parametric images in three-dimensional PET when the kinetic model is linear in its parameters (Patlak plot) and compare with indirectly estimated parametric maps, where the radioactivity distribution was estimated by the filtered back projection and ordered subsets expectation maximization algorithms. Both real and simulated data for tracers with irreversible kinetics in brain studies are included. The results demonstrate appreciable smaller standard deviation and mean squared error characteristics for the direct reconstruction. However, some regions may converge slowly. The FBP and ordered subsets expectation maximization (OSEM) indirect estimations have a similar level of bias after matching their resolutions, but OSEM has smaller standard deviation.     

基于图像对比度分析的自适应超声声速优化

本文提出一种基于图像对比度分析的自适应声速优化技术,从而实时得到对比度增强、组织结构清晰可见的超声影像。论文首先描述超声系统动态延迟聚焦的波束形成过程,并引入系统声速以及组织真实声速等概念,进而讨论其两者不匹配对图像品质的影响。介绍图像灰度值表示的对比度之后,论文阐述了准确估计与组织声速一致的系统声速的基本原理。最后,论文通过已知声速的仿人体组织体模和真实人体组织超声影像来验证,并与已有声速优化方法进行比较。实验结果不仅表明本研究所估计的声速是准确的,而且算法运算速度亦适用于超声系统的实时应用。     

一种在PC上实现三维医学图像实时旋转的方法

实时旋转是三维医学图示中的一个重要环节，但巨大的显示数据量使旋转在普通微机上成为一个难以解决的问题，本文提出的旋转与显示分离技术，采用先旋转，而后再显示的方法，巧妙解决了该问题，使得大数据量的三维学图像在普通微机上实时旋转成为可能。     

A real time collaboration system for teleradiology consultation

Real time collaboration systems, in which participants share multimedia data and applications in real time, have attracted many researchers in recent years. A teleradiology consultation system based on the real time collaboration technology is presented in this paper. Under the platform-independence consideration, Java technologies are employed to construct the system. Applying this system, an off-duty on-call radiologist can make diagnoses and report easily by viewing the transferred images at home. Owing to the accessibility of image, all users can examine and manipulate images consistently such that a secluded hospital can be assisted to hold remote consultation. To reduce the network transmission time, the command-passing and local command execution techniques are utilized to achieve the screen synchronization. A pointer function is also developed to maintain the cursor consistency in a more efficient manner during consultation when a detail indication of the examined image is needed. Besides, a dialog window is also designed for on-line conversation. Since Java programs can run on heterogeneous platforms, the need for system maintenance and user training can be substantially reduced.     

Subsystem throughputs of a clinical picture archiving and communications system

We measured the throughtput rates of individual picture archiving and communications system (PACS) subsystems including the acquisition, archive, display, and communication network as a basis of evaluation the overall throughput of our clinical PACS. The throughput rate of each PACS subsystem was measured in terms of average residence time of individual images in the subsystem. The residence time of an image in a PACS subsystem was determined by the total time the image was required to be processed within the subsystem. The overall throughput of the PACS was measured as the total residence time of an image in the various subsystems. We also measured throughputs of the PACS subsystems using three types of networks (Ethernet; fiber distributed data interface; and UltraNet, UltraNetwork Technologies, San Jose, CA), and the results were compared. Approximately 200 gigabytes of data transactions including magnetic resonance, computed tomography and computed radiography images from our PACS were analyzed. Results showed that PACS throughput was limited by three major factors: (1) low-speed data interface used in the radiologic imaging devices and archive devices; (2) competition for systems processing time among the PACS processes; and (3) network degradation caused by heavy network traffic. We concluded that PACS performance could be improved with a well-designed network architecture, a job prioritizing mechanism, and an image routing strategy. However, device-dependent low-speed data interface has limited PACS performance.     

基于电磁定位的超声图像与CT图像的融合方法

在超声引导经皮介入治疗中,为集成多模态图像信息来弥补单一超声图像的不足,提出一种实时超声图像与CT图像的融合方法,使临床医生在实施介入治疗时得到患者病灶的多模态图像信息成为可能。首先,利用电磁定位系统,得到12个铅球球心的磁场坐标和CT图像坐标,利用两个点集的ICP配准算法,将磁场坐标系和CT图像坐标系进行配准;其次,利用电磁定位系统,将和超声探头固连在一起的电磁传感器自身坐标系与磁场坐标系进行配准;然后,利用超声探头的机械设计尺寸,将超声坐标系与电磁传感器自身坐标系进行配准;最后,通过多个坐标系的转换关系将超声坐标系配准到CT图像坐标系,最终将实时超声图像统一到CT图像中,并在软件中测量融合误差。在该方法下,实时超声图像与CT图像的融合误差为(0.71±0.03)mm,在软件中可以清晰地看到两种图像的实时融合效果。因此,该方法可以有效地将实时超声图像与CT图像进行融合,为介入治疗的精准性提供相应的技术支持。