MyFreePACS: a free web-based radiology image storage and viewing tool

OBJECTIVE: We developed an easy-to-use method for central storage and subsequent viewing of radiology images for use on any PC equipped with Internet Explorer. CONCLUSION: We developed MyFreePACS, a program that uses a DICOM server to receive and store images and transmit them over the Web to the MyFreePACS Web client. The MyFreePACS Web client is a Web page that uses an ActiveX control for viewing and manipulating images. The client contains many of the tools found in modern image viewing stations including 3D localization and multiplanar reformation. The system is built entirely with free components and is freely available for download and installation from the Web at www.myfreepacs.com.     

Technologies for image distribution in hospitals

After the establishment of web-based image distribution, three challenges for image distribution can be identified today. Firstly, PACS (picture archiving and communication system) and the distribution of radiological images and reports need to be integrated with the emerging electronic medical record. Secondly, report and image data should be available on mobile devices like PDAs (personal digital assistants) or smartphones in the future. Thirdly, future systems must be available not only to transmit sectional images, but also to allow access to three- and four-dimensional data that are produced by multidetector CT and modern MR scanners.     

Enterprise PACS and image distribution.

Around the world now, because of the need to improve operation efficiency and better cost effective healthcare, many large-scale healthcare enterprises have been formed. Each of these enterprises groups hospitals, medical centers, and clinics together as one enterprise healthcare network. The management of these enterprises recognizes the importance of using PACS and image distribution as a key technology in cost-effective healthcare delivery in the enterprise level. As a result, many large-scale enterprise level PACS/image distribution pilot studies, full design and implementation, are underway. The purpose of this paper is to provide readers an overall view of the current status of enterprise PACS and image distribution. reviews three large-scale enterprise PACS/image distribution systems in USA, Germany, and South Korean. The concept of enterprise level PACS/image distribution, its characteristics and ingredients are then discussed. Business models for enterprise level implementation available by the private medical imaging and system integration industry are highlighted. One current system under development in designing a healthcare enterprise level chest tuberculosis (TB) screening in Hong Kong is described in detail.     

The integration of medical images with the electronic patient record and their web-based distribution

Medical images are currently created digitally and stored in the radiology department's picture archiving and communication system. Reports are usually stored in the electronic patient record of other information systems, such as the radiology information system (RIS) and the hospital information system (HIS). But high-quality services can only be provided if electronic patient record data is integrated with digital images in picture archiving and communication systems. Clinicians should be able to access both systems' data in an integrated and consistent way as part of their regular working environment, whether HIS or RIS. Also, this system should allow for teleconferencing with other users, eg, for consultation with a specialist in the radiology department. This article describes a web-based solution that integrates the digital images of picture archiving and communication systems with electronic patient record/HIS/RIS data and has built-in teleconferencing functionality. This integration has been successfully tested using three different commercial RIS and HIS products.     

PACS and Web-based image distribution and display.

Picture archiving and communication system (PACS) delivers images to the display workstations mostly through digital image communication in medicine (DICOM) protocols in radiology departments, and there are lots of medical applications in healthcare community needing to access PACS images for different application purposes. In this paper, we first reviewed a hospital-integrated PACS image data flow and typical diagnostic display software architecture, and discussed some Web technologies and Web-based image application server architectures, as well as image accessing and viewing methods in these architectures. Then, we present one approach to develop component-based image display architecture and use image processing and display component to build a diagnostic display workstation, and also, give a method to integrate this component into Web-based image distribution server to enable users using Web browsers to access, view and manipulate PACS DICOM images as easy as with PACS display workstations. Finally, we test and evaluate the performance of image loading and displaying by using the diagnostic display workstation and the component-based Web display system, the experimental results show that the image distribution and display performance from the Web server to browser clients is similar with that of the image loading and displaying procedure of the diagnostic workstation as more browser clients accessing the Web server at same time. We also discuss the advantages and disadvantages of the Web-based image distribution and display in different medical applications.     

Performance of Web-based image distribution: server-oriented measurements

The aim of this study was to assess the performance of Web-based image distribution when multiple personal computers (PCs) are downloading images simultaneously for different server hardware configurations. Using specially developed software, the time-to-display (TTD) of different image types was measured with up to 16 concurrent PCs for various combinations of processor, random access memory (RAM), network connection and image compression. The TTD increased linearly with the number of concurrent PCs but remained under 5 s in most of the cases, even with 16 concurrent PCs. Only with a 10-Mbit/s network connection or with lossy compression were TTDs above 5 s obtained. Two processors instead of one led to a slight and constant improvement of the TTD. Reducing the amount of RAM increased the TTD mainly for computed radiography (CR) images. There was no difference between a 200- and 100-Mbit/s network, but 10 Mbit/s proved significantly worse. When increasing the number of clients lossless compression performed substantially better than lossy. A standard off-the-shelf server provides an appropriate download performance even with 16 concurrent clients. Processor speed and RAM amount are of minor importance, but it is highly recommended to use a 100-Mbit/s network connection and to avoid the application of on-demand lossy compression in a local area network.     

Performance of Web-based image distribution: client-oriented measurements

The aim of this study was to define a clinically suitable personal computer (PC) configuration for Web-based image distribution and to assess the influence of different hard- and software configurations on the performance. Through specially developed software the time-to-display (TTD) for various PC configurations was measured. Different processor speeds, random access memory (RAM), screen resolutions, graphic adapters, network speeds, operating systems and examination types (computed radiography, CT, MRI) were evaluated, providing more than half a million measurements. Processor speed was the most relevant factor for the TTD; doubling the speed halved the TTD. Under processor speeds of 350 MHz, TTD mostly remained above 5 s for 1 CR or 16 CT images. Here Windows NT with lossy compression were superior. Processor speeds of 350 MHz and over delivered TTD <5 s. In this case Windows 2000 and lossless compression were preferable. Screen resolutions above 1280×1024 pixels increased the TTD mainly for CR images. The RAM amount, network speed and graphic adapter did not have a significant influence. The minimum threshold for clinical routine is any standard off-the-shelf PC better than Pentium II 350 MHz, 128 MB RAM; hence, high-end PC hardware is not required.     

Image processing methods to obtain symmetrical distribution from projection image.

Flow visualization and measurement of cross-sectional liquid distribution is very effective to clarify the effects of obstacles in a conduit on heat transfer and flow characteristics of gas-liquid two-phase flow. In this study, two methods to obtain cross-sectional distribution of void fraction are applied to vertical upward air-water two-phase flow. These methods need projection image only from one direction. Radial distributions of void fraction in a circular tube and a circular-tube annuli with a spacer were calculated by Abel transform based on the assumption of axial symmetry. On the other hand, cross-sectional distributions of void fraction in a circular tube with a wire coil whose conduit configuration rotates about the tube central axis periodically were measured by CT method based on the assumption that the relative distributions of liquid phase against the wire were kept along the flow direction.     

A dose distribution overlay technique for image guidance during prostate radiotherapy

Adaptive radiotherapy involves altering the treatment plan according to variations in patient anatomy and set-up. This relies upon an accurate representation of the changing dose distribution within the patient, requiring a full dose recalculation. This work proposes a novel workflow using the planned dose distribution to assess dose coverage in three-dimensional verification CT studies acquired at the time of treatment delivery, using an overlay technique, in lieu of a recalculated dose distribution. The concept has been validated in a pilot study of 10 patients, each with 7-10 on-treatment CT studies. Differences between the geometric shape of the treatment plans for the 95% isodose and the 95% isodose obtained when the planned geometry was recalculated from the verification CT dataset were quantified. Dosimetric coverage of the verification clinical target volume (vCTV) was assessed for both the proposed overlay technique and the recalculated "delivered" dose distribution, and the conclusions on adequacy were compared. Results were consistent with geometric uncertainties of the dose calculation matrix (5 x 5 x 5 mm), suggesting that differences in the geometric shape of the 95% isodose are not significant for normal variations in patients' anatomy. Decisions on adequacy of vCTV coverage were consistent in 80 out of 87 cases, with discrepancies limited to a maximum of three axial slices per study within the range 0.5-4.5 mm (mean, 1.6 mm). The proposed dosimetric overlay technique has been validated and found to be an acceptable method of image-guided radiotherapy of the prostate suitable for effective implementation in the treatment clinic.     

网络环境下计算机课堂教学模式初探

在比较网络教学模式与传统教学模式之后，提出了网络环境下，计算机课堂教学模式的具体做法，并对效果进行了评价，最后讨论了在实际教学过程中应该注意的问题。     

鼠疫耶尔森菌文献数据库的研建与开发

目的 建立便捷的鼠疫菌文献数据库系统,从而提高文献利用效率.方法 运用EndNote X5文献管理软件进行文献收集整理,通过Perl及PHP等计算机语言规范数据格式、构建实体关系模型、搭建系统和开发网页;选择中小型网站开发中常用的Apache+PHP+MySQL组合进行动态网站的开发.结果与结论 构建了鼠疫菌文献数据库(访问地址:http://101.201.51.148/ypkd/).该文献数据库可供用户快速检索、浏览并获取鼠疫菌相关文献和著作全文,并提供自动更新的鼠疫菌新闻资讯.该数据库具有前沿性和完整性,为鼠疫菌相关科研及鼠疫疫情的预防控制提供了知识保障,并为其他重要病原文献数据库的建立提供了参考模型.     

Creating an international comprehensive web-based curriculum in pediatric radiology

OBJECTIVE: This article describes the creation of a standardized comprehensive resident curriculum in pediatric radiology that uses adult learning principles authored by international experts and addresses the six general competencies required by the Accreditation Council for Graduate Medical Education. CONCLUSION: Web-based learning with an online curriculum has the potential to become an integral component of residency training. The use of radiology experts as authors allows compilation of an authoritative, comprehensive, and current body of knowledge that enhances the current teaching file approach to Web-based instruction in radiology. We describe the approach, design, and tools necessary for the construction of a complete Web-based curriculum in pediatric radiology that includes self-assessment through pre- and post-testing, text with interactive images, curriculum evaluation, and the ability to record trainee demographics.     

Adaptive Wiener filter based on Gaussian mixture distribution model for denoising chest X-ray CT image

In recent decades, X-ray CT imaging has become more important as a result of its high-resolution performance. However, it is well known that the X-ray dose is insufficient in the techniques that use low-dose imaging in health screening or thin-slice imaging in work-up. Therefore, the degradation of CT images caused by the streak artifact frequently becomes problematic. In this study, we applied a Wiener filter (WF) using the universal Gaussian mixture distribution model (UNI-GMM) as a statistical model to remove streak artifact. In designing the WF, it is necessary to estimate the statistical model and the precise co-variances of the original image. In the proposed method, we obtained a variety of chest X-ray CT images using a phantom simulating a chest organ, and we estimated the statistical information using the images for training. The results of simulation showed that it is possible to fit the UNI-GMM to the chest X-ray CT images and reduce the specific noise.     

Evaluation of radiological workstations and web-browser-based image distribution clients for a PACS project in hands-on workshops

The methodology and outcome of a hands-on workshop for the evaluation of PACS (picture archiving and communication system) software for a multihospital PACS project are described. The following radiological workstations and web-browser-based image distribution software clients were evaluated as part of a multistep evaluation of PACS vendors in March 2001: Impax DS 3000 V 4.1/Impax Web1000 (Agfa-Gevaert, Mortsel, Belgium); PathSpeed V 8.0/PathSpeed Web (GE Medical Systems, Milwaukee, Wis., USA); ID Report/ID Web (Image Devices, Idstein, Germany); EasyVision DX/EasyWeb (Philips Medical Systems, Eindhoven, Netherlands); and MagicView 1000 VB33a/MagicWeb (Siemens Medical Systems, Erlangen, Germany). A set of anonymized DICOM test data was provided to enable direct image comparison. Radiologists (n=44) evaluated the radiological workstations and nonradiologists (n=53) evaluated the image distribution software clients using different questionnaires. One vendor was not able to import the provided DICOM data set. Another vendor had problems in displaying imported cross-sectional studies in the correct stack order. Three vendors (Agfa-Gevaert, GE, Philips) presented server-client solutions with web access. Two (Siemens, Image Devices) presented stand-alone solutions. The highest scores in the class of radiological workstations were achieved by ID Report from Image Devices (p<0.005). In the class of image distribution clients, the differences were statistically not significant. Questionnaire-based evaluation was shown to be useful for guaranteeing systematic assessment. The workshop was a great success in raising interest in the PACS project in a large group of future clinical users. The methodology used in the present study may be useful for other hospitals evaluating PACS.     

A web-based test of residents' skills in diagnostic radiology.

PURPOSE: To develop an objective, Web-based tool for evaluating residents' knowledge of diagnostic radiology. METHODS: We developed and tested a Web-based evaluation tool (the Diagnostic Radiology Skills Test) that consists of 3 tests, one in each of 3 domains of diagnostic radiology: chest, gastrointestinal, and musculoskeletal imaging. Each test comprises 30 cases representing a range of difficulty in the domain, including normal states, normal variants, typical cases of common diagnoses, and cases with more subtle findings. Cases are presented with a long menu of domain-specific possible diagnoses (response options), each coded for diagnostic appropriateness. Our subjects were 21 residents in postgraduate year (PGY) 2 to 5 and 11 experts in diagnostic radiology. Subjects accessed the tool via a Web site on our Web server. Residents' test results were compared for reliability and validity across domain, case, and training level. In addition, results were correlated with commonly used established and objective evaluation tools. RESULTS: The tool demonstrated consistent monotonic improvement in performance with training level. It showed acceptable reliability in discriminating between residents at different performance levels, both within and across training levels (r= 0.53 within level and 0.69 across levels). Test results also had concurrent validity against the American College of Radiology In-Training Examination, a widely accepted objective assessment tool (r = 0.65, P < 0.01), and 2 Objective Structured Clinical Examinations (OSCEs) focusing on diagnostic skills (r= 0.78 and r= 0.69, P < 0.01, respectively). CONCLUSIONS: Our study demonstrates the feasibility of a Web-based, standardized, objective assessment method for evaluating residents' performance.     

FBP和OSEM对正常人脑内多巴胺转运体分布半定量值影响的研究

目的 研究不同PET重建方法对正常人脑内多巴胺转运体（DAT）分布半定量值的影响。方法 将2014年3月至2015年6月期间41例健康受试者（正常人）的11C-甲基-N-2β-甲基酯-3β-（4-氟-苯基）托烷（11C-CFT）PET图像分别进行滤波反投影法（FBP）和有序子集最大期望值迭代法（OSEM）重建,自动勾画尾状核、壳核前部和后部等感兴趣脑区,以缺乏DAT分布的顶枕皮质作为参考区,按公式计算DAT分布的半定量值。DAT分布半定量值的组间比较采用配对t检验,相关性分析采用Pearson相关分析法。结果 基于OSEM重建的PET图像中DAT分布半定量值分别为:尾状核（1.77~2.15）、壳核前部（2.17~2.39）、壳核后部（1.71~2.06）;基于FBP重建的PET图像中DAT分布半定量值分别为:尾状核（1.68~2.10）、壳核前部（2.07~2.37）、壳核后部（1.62~1.96）。基于OSEM重建的PET图像中双侧尾状核、壳核前部及后部的DAT分布半定量值均显著高于基于FBP重建的PET图像,且两者间的差异均有统计学意义（t=9.658~15.859,均P=0.000）。Pearson相关性分析结果显示,基于OSEM与FBP重建的PET图像的DAT分布半定量值在双侧尾状核、壳核前部及后部均呈显著正相关（R2=0.907~0.951,均P=0.000）。基于OSEM与FBP重建的PET图像中双侧尾状核、壳核前部及后部DAT分布半定量值均呈现随年龄增长逐渐减低的趋势。结论 不同PET重建方法获得的正常人脑内DAT分布半定量值存在显著差异,在多中心或纵向研究中需要保持PET图像重建方法的一致性。     

Manipulation of image intensity distribution at 7.0 T: passive RF shimming and focusing with dielectric materials

PURPOSE: To investigate the effects of high dielectric material padding on RF field distribution in the human head at 7.0 T, and demonstrate the feasibility and effectiveness of RF passive shimming and focusing with such an approach. MATERIALS AND METHODS: The intensity distribution changes of gradient-recalled-echo (GRE) and spin-echo (SE) images of a human head acquired with water pads (dielectric constant = 78) placed in specified configurations around the head at 7.0 T were evaluated and compared with computer simulation results using the finite difference time domain (FDTD) method. The contributions to the B(1) field distribution change from the displacement current and conductive current of a given configuration of dielectric padding were determined with computer simulations. RESULTS: MR image intensity distribution in the human head with an RF coil at 7.0 T can be changed drastically by placing water pads around the head. Computer simulations reveal that the high permittivity of water pads results in a strong displacement current that enhances image intensity in the nearby region and alters the intensity distribution of the entire brain. CONCLUSION: The image intensity distribution in the human head at ultra-high field strengths can be effectively manipulated with high permittivity padding. Utilizing this effect, the B(1) field inside the human head of a given RF coil can be adjusted to reduce the B(1) field inhomogeneity artifact associated with the wave behavior (RF passive shimming) or to locally enhance the signal-to-noise ratio (SNR) in targeted regions of interest (ROIs; RF field focusing).