In the past 20 years, a number of acronyms have been used to describe radiographic image management functions to achieve flimless radiology. These functions include acquisition, networking, workstation displays, archiving, image data compression, and patient data information management. The PACS acronym (picture archiving and communication system) was proposed by Dr. Judith Prewitt (at NIH when proposed) and freely used in the first PACS Conference (Duerinckx, 1982).! An alternative acronym proposed and used was image management and communication (system), IMAC, network, originated by Seong K. Mun,2 Georgetown University. An acronym of IDS (integrated diagnostic system) was proposedby de Valk.3 These changing acronyms represented the levels of difficulty at various times in the technology for implementing a radiology imaging management system. Yet, the most commonly used acronym remains PACS. In the early 1980's, archiving and communication functions were difficult to implement due to the status of archiving and communications technology. There is a wealth ofpublished material regarding PACS. One ofthe leading resources is the Proceedings ofthe International Society for Optical Engineering (SPIE) workshop on PACS Design and Evaluation. This workshop has been held every year in February during the SPIE Medical Imaging yearly conference. Papers for the SPIE meeting are selected and accepted based upon a submitted abstract. Posters are selected from the same set of submitted papers (examples48). The SPIE Proceedings are papers that are prepared by authors, providing the latest PACS implementation. An outstanding source of PACS papers is the Journal ofDigital Imaging, the Editor being Roger A. Bauman, M.D. This is the officialjoumal of the Society for Computer Applications in Radiology (SCAR). It begin publication in 1988 and is indexed in the Index Medicus. Several books are available dedicated to PACS. Among these books are the following: (a) J. P. J. de Valk (ed), Integrated Diagnostic Imaging, Elsevier Science Publishers, The Netherlands (1992); (b) H. K. Huang, PACS, VCH Publishers, N.Y. (1996); and (c) E. L. Siegal, R.M. Kolodner, Filmiess Radiology, Springer Medicine, 1998. In addition, the Journal of Radiology and the American Journal of Roentgenology often publish peer-reviewed papers on aspects of PACS. Like many other computer applications in radiology, there is no lack of publication sources available for good PACS papers. Sources available for a PACS history are extensive. A cursory estimate is that over 3,000 published articles exist and the classification of these published articles and papers is difficult. For purposes of this history, the segmentation is shown in Figure 1 . Also, cited papers are limited to one single category. Each division in Figure 1 will be limited to but a few cited references. This does not mean that the many other published papers that are not cited, are considered second-class papers. And, the selection and classification ofpapers was the sole responsibility of the author of this paper. A true history of PACS requires a group of experts selecting the key papers to be cited.9 It can be argued that a PACS history over the past twenty years will be difficult to accomplish due to changing technology (always improving), serious modifications to the health care system, changes in the imaging systems used by radiologists in providing services to the practicing physician and the patient, and the many vendor changes.

Picture Archiving and Communication Systems (PACS) is a concept followed since the early 1980's by the radiological community as a future method of practicing radiology. Some of the seminal papers for PACS were published in 1982. Although publications by Duerinckx, Maguiere, Horii, and Dwyer are generally considered to be the first PACS description in literature, there have been descriptions of similar concepts before the 1980's, e.g. relating to workstations for medical image processing and to IMAC (Image Management and Communication). Soon after the first SPIE international symposium on PACS in the USA, first attempts of a filmless radiological department were made in Europe. The countries particularly active were the Netherlands, Belgium, France, Italy, Austria, Germany, and the U.K.

1971/72 began the implementation of a computerized radiological documentation system as the Department of Radiology of the University of Graz, which developed over the years into a full RIS. 1985 started a scientific cooperation with SIEMENS to develop a PACS. The two systems were linked and evolved into a highly integrated RIS-PACS for the state wide hospital system in Styria. During its lifetime the RIS, originally implemented in FORTRAN on a UNIVAC 494 mainframe migrated to a PDP15, on to a PDP11, then VAX and Alphas. The flexible original record structure with variable length fields and the powerful retrieval language were retained. The data acquisition part with the user interface was rewritten several times and many service programs have been added. During our PACS cooperation many ideas like the folder concept or functionalities of the GUI have been designed and tested and were then implemented in the SIENET product. The actual RIS/PACS supports the whole workflow in the Radiology Department. It is installed in a 2.300 bed university hospital and the smaller hospitals of the State of Styria. Modalities from different vendors are connected via DICOM to the RIS (modality worklist) and to the PACS. PACSubsystems from other vendors have been integrated. Images are distributed to referring clinics and for teleconsultation and image processing and reports are available on line to all connected hospitals. We spent great efforts to guarantee optimal support of the workflow and to ensure an enhanced cost/benefit ratio for each user (class). Another special feature is selective image distribution. Using the high level retrieval language individual filters can be constructed easily to implement any image distribution policy agreed upon by radiologists and referring clinicians.

The goal of this project is to develop and implement off-line DICOM-compliant CD ROMs that contain the necessary software tools for displaying the images and related data on any personal computer. We implemented a hybrid recording technique allowing CD-ROMs for Macintosh and Windows platforms to be fully DICOM compliant. A public domain image viewing program (OSIRIS) is recorded on the CD for display and manipulation of sequences of images. The content of the disk is summarized in a standard HTML file that can be displayed on any web-browser. This allows the images to be easily accessible on any desktop computer, while being also readable on high-end commercial DICOM workstations. The HTML index page contains a set of thumbnails and full-size JPEG images that are directly linked to the original high-resolution DICOM images through an activation of the OSIRIS program. Reports and associated text document are also converted to HTML format to be easily displayable directly within the web browser. This portable solution provides a convenient and low cost alternative to hard copy images for exchange and transmission of images to referring physicians and external care providers without the need for any specialized software or hardware.

The U.S. Department of Veterans Affairs (VA) is using the Digital Imaging and Communications in Medicine (DICOM) standard to integrate image data objects from multiple systems for use across the healthcare enterprise. DICOM uses a structured representation of image data and a communication mechanism that allows the VA to easily acquire images from multiple sources and store them directly into the online patient record. The VA can obtain both radiology and non- radiology images using DICOM, and can display them on low-cost clinician's color workstations throughout the medical center. High-resolution gray-scale diagnostic quality multi-monitor workstations with specialized viewing software can be used for reading radiology images. The VA's DICOM capabilities can interface six different commercial Picture Archiving and Communication Systems (PACS) and over twenty different image acquisition modalities. The VA is advancing its use of DICOM beyond radiology. New color imaging applications for Gastrointestinal Endoscopy and Ophthalmology using DICOM are under development. These are the first DICOM offerings for the vendors, who are planning to support the recently passed DICOM Visible Light and Structured Reporting service classes. Implementing these in VistA is a challenge because of the different workflow and software support for these disciplines within the VA HIS environment.

The exchange of medical images over networks or storage media is usually done in DICOM format today. In addition to uncompressed image storage, DICOM supports both lossless and lossy image compression techniques. Whereas lossless compression is popular for some applications, lossy compression in DICOM has never gained intensive usage. However, the quickly rising data volumes produced by the latest generation of modalities indicate that compression will remain an important issue although network bandwidth and storage capacities are increasing as well. The study presented in this contribution examines the conditions under which existing uncompressed DICOM images can be compressed with lossless and lossy JPEG resulting in valid DICOM images. The aim of the study was to enhance an existing open-source DICOM toolkit with JPEG support such that a wide range of DICOM images can be processed. Since image compression is not an integral part of the DICOM data model, its introduction can lead to surprising conflicts, e.g. because the special requirements of certain modalities do not match the JPEG model or because ambiguities in the standard are interpreted differently by different implementers. The resolution of the existing ambiguities could help to make DICOM image compression more robust in the future.

DICOM is today's de-facto standard for exchanging medical images. Since new image acquisition devices produce more and more image and non-image data, image compression has become an important part of the standard. However, the compression of non-pixel data also stored in DICOM data sets has been disregarded up to now. In the scope of an EU research project we have examined a large amount of real-world DICOM images to test whether or not there is a potential for compressing the non-pixel attributes. As a result we have found out that it is indeed possible to reduce the size of header information in DICOM data sets significantly. However, the contribution to the overall compression ratio is very small. We conclude that compression of DICOM header information is only interesting for data sets which mainly consist of non-pixel data. Since new DICOM modalities introduce more and more of such data, the importance of this issue is likely to increase. Also many DICOM network services are based on more or less large 'textual' data structures. Especially for use with narrow-band networks extensions as proposed in this paper could be a solution to save valuable bandwidth.

The goal of the DICOM standard is to define a standard network interface and data model for imaging devices from various vendors. DICOM does not specify implementation-specific requirements and does not specify a testing procedure to assess an implementations conformance to the standard. The conformance statements defined in the DICOM standard only allow a user to determine that which optional components are supported by the implementation. As the DICOM 3.0 standard becomes the official standard in the medical imaging field, there are many available systems and software which support DICOM. But, user can't get any other information about the system and the software other than the conformance which the several vendors offer. Because of this, it is necessary that one test the conformance of the system and the software of vendors and offer the results to both users and vendors. We implement the Test Station of the DICOM 3.0 standard. The main purpose of the Test Station is to measure the reliability of the vendors software and to report this for those using the suggestion.

Proprietary compression schemes have a cost and risk associated with their support, end of life and interoperability. Standards reduce this cost and risk. The new JPEG-LS process (ISO/IEC 14495-1), and the lossless mode of the proposed JPEG 2000 scheme (ISO/IEC CD15444-1), new standard schemes that may be incorporated into DICOM, are evaluated here. Three thousand, six hundred and seventy-nine (3,679) single frame grayscale images from multiple anatomical regions, modalities and vendors, were tested. For all images combined JPEG-LS and JPEG 2000 performed equally well (3.81), almost as well as CALIC (3.91), a complex predictive scheme used only as a benchmark. Both out-performed existing JPEG (3.04 with optimum predictor choice per image, 2.79 for previous pixel prediction as most commonly used in DICOM). Text dictionary schemes performed poorly (gzip 2.38), as did image dictionary schemes without statistical modeling (PNG 2.76). Proprietary transform based schemes did not perform as well as JPEG-LS or JPEG 2000 (S+P Arithmetic 3.4, CREW 3.56). Stratified by modality, JPEG-LS compressed CT images (4.00), MR (3.59), NM (5.98), US (3.4), IO (2.66), CR (3.64), DX (2.43), and MG (2.62). CALIC always achieved the highest compression except for one modality for which JPEG-LS did better (MG digital vendor A JPEG-LS 4.02, CALIC 4.01). JPEG-LS outperformed existing JPEG for all modalities. The use of standard schemes can achieve state of the art performance, regardless of modality, JPEG-LS is simple, easy to implement, consumes less memory, and is faster than JPEG 2000, though JPEG 2000 will offer lossy and progressive transmission. It is recommended that DICOM add transfer syntaxes for both JPEG-LS and JPEG 2000.

A multi-institution effort was conducted to assess the visual quality performance of various JPEG 2000 (Joint Photographic Experts Group) lossy compression options for medical imagery. The purpose of this effort was to provide clinical data to DICOM (Digital Imaging and Communications in Medicine) WG IV to support recommendations to the JPEG 2000 committee regarding the definition of the base standard. A variety of projection radiographic, cross sectional, and visible light images were compressed-reconstructed using various JPEG 2000 options and with the current JPEG standard. The options that were assessed included integer and floating point transforms, scalar and vector quantization, and the use of visual weighting. Experts from various institutions used a sensitive rank order methodology to evaluate the images. The proposed JPEG 2000 scheme appears to offer similar or improved image quality performance relative to the current JPEG standard for compression of medical images, yet has additional features useful for medical applications, indicating that it should be included as an additional standard transfer syntax in DICOM.

The DICOM standard defines in detail how medical images can be transmitted and stored. However, there have been no precise rules on how to interpret the parameters contained in a DICOM image which deal with the image presentation. As a result, the same image frequently looks different when displayed on different workstations or printed on a film from various printers. Three new DICOM extensions attempt to close this gap by defining a comprehensive model for the display of images on softcopy and hardcopy devices: Grayscale Standard Display Function, Grayscale Softcopy Presentation State and Presentation Look Up Table. A prototype implementation of these extensions has been shown at the 1999 annual tradeshow of the Radiological Society of North America (RSNA) as part of the scientific exhibit (infoRAD). This demonstrated a simulated radiological workflow in which images were created, interpreted at a diagnostic workstation and later reviewed on a clinical workstation. Images could also be printed using DICOM Print. The prototype shows a proof of concept, i.e. that image integrity and consistency over a variety of display and print devices can be achieved and in addition, that the new DICOM extensions can be implemented relatively easily, without a significant performance penalty. The extensions allow to store all parameters defining how an image is displayed or printed in a separate DICOM object that can be managed with the existing DICOM database services. In particular, this satisfies the user's need to view images at different locations in a consistent manner, and to document the image appearance on which a diagnosis is made in softcopy environments.

This study evaluates the usefulness of wavelet compression for resolution-enhanced storage phosphor chest radiographs in the detection of subtle interstitial disease, pneumothorax and other abnormalities. A wavelet compression technique, MrSID^TM (LizardTech, Inc., Seattle, WA), is implemented which compresses the images from their original 2,000 by 2,000 (2K) matrix size, and then decompresses the image data for display at optimal resolution by matching the spatial frequency characteristics of image objects using a 4,000- square matrix. The 2K-matrix computed radiography (CR) chest images are magnified to a 4K-matrix using wavelet series expansion. The magnified images are compared with the original uncompressed 2K radiographs and with two-times magnification of the original images. Preliminary results show radiologist preference for MrSID^TM wavelet-based magnification over magnification of original data, and suggest that the compressed/decompressed images may provide an enhancement to the original. Data collection for clinical trials of 100 chest radiographs including subtle interstitial abnormalities and/or subtle pneumothoraces and normal cases, are in progress. Three experienced thoracic radiologists will view images side-by- side on calibrated softcopy workstations under controlled viewing conditions, and rank order preference tests will be performed. This technique combines image compression with image enhancement, and suggests that compressed/decompressed images can actually improve the originals.

In this paper, we present the performance evaluation of wavelet-based coding techniques as applied to the compression of pathological images for application in an Internet-based telemedicine system. We first study how well suited the wavelet-based coding is as it applies to the compression of pathological images, since these images often contain fine textures that are often critical to the diagnosis of potential diseases. We compare the wavelet-based compression with the DCT-based JPEG compression in the DICOM standard for medical imaging applications. Both objective and subjective measures have been studied in the evaluation of compression performance. These studies are performed in close collaboration with expert pathologists who have conducted the evaluation of the compressed pathological images and communication engineers and information scientists who designed the proposed telemedicine system. These performance evaluations have shown that the wavelet-based coding is suitable for the compression of various pathological images and can be integrated well with the Internet-based telemedicine systems. A prototype of the proposed telemedicine system has been developed in which the wavelet-based coding is adopted for the compression to achieve bandwidth efficient transmission and therefore speed up the communications between the remote terminal and the central server of the telemedicine system.

The concept of PACS was initiated in 1982 during the First International Conference and Workshop on Picture Archiving and Communication System, held in Newport Beach, California, January 1982, sponsored by SPIE. During the past seventeen years, many large and small PAC systems have been installed and are running smoothly. Around the world, many more systems will be planned and installed for years to come. This paper describes the author's personal PACS implementation experience including in-house development, partnership with manufacturers, and participation as a member of the advisory board in both the hospital and the manufactures. In the latter case, three examples are described for a very large urban hospital, a small community hospital, and a PACS manufacturer in the Far East. Lessons learned from each case are given.

The diffusion of PACS technology within the Department of Veterans Affairs has followed the 'S' curve transition originally described by Ryan and Gross in 1943. They described a paradigm that describes the diffusion of a new technology into the community. However the rate of adoption of filmless radiology by the VA has been much higher than that of the general healthcare system. This is likely due to the fact that the VA and Department of Defense medical systems are somewhat isolated and independent from other health care systems and are subject to a different rate of diffusion of technology. The early introduction and success of PACS in the VA undoubtedly accelerated its acceptance throughout the system. An additional impetus to the growth of PACS in the VA has been the development of an image management system that has been incorporated into the electronic medical record. The universal use of the VISTA HIS and RIS system throughout the VA and the fact that it was developed 'in-house' as well as its extensive support for DICOM functionality have also played a major role in facilitating the acceptance of Picture Archival and Communication Systems throughout the VA.

The Department of Defense has been a leader in Radiology re- engineering for the past decade. Efforts have included the development of two landmark PACS specifications (MDIS and DIN- PACS), respective vendor selection and implementation programs. A Tri-Service (Army, Navy and Air Force) Radiology re-engineering program was initiated which identified transitioning to digital imaging, PACS and teleradiology as key enabling technologies in a changing business scenario. Subsequently, the systematic adjustment of procurement process for radiological imaging equipment included a focus on specifying PACS-capable-digital imaging modalities and mini- PACS as stepping stones to make the hospitals and health clinics PACS-ready. The success of the PACS and teleradiology program in the DOD is evidenced by the near filmless operation of most Army and Air Force Medical Centers, several community hospitals and several operational teleradiology constellations. Additionally, the MDIS PACSystem has become the commercial PACS product for General Electric Medical Systems. The DOD continues to forge ahead in the PACS arena by implementing advanced configurations and operational concepts such as the VRE (Virtual Radiology Environment), the negotiation of Regional Archiving and Regional PACS Maintenance Programs. Newer regulations (HIPAA, the FDA approval of digital mammography) have been promulgated impacting the culture and conduct of our business. Incorporating their requirements at the very outset will enable us to streamline the delivery of radiology. The DOD community has embraced the information age at multiple levels. The Healthcare portion of this community with these initiatives is integrating itself into DOD's future. The future holds great possibilities, promises and challenges for the DOD PACS programs.

It is now possible to replace film-based image management in the cardiac catheterization laboratory with a Cardiology Picture Archiving and Communication System (Cardio-PACS) based on digital imaging technology. The first step in the conversion process is installation of a digital image acquisition system that is capable of generating high-quality DICOM-compatible images. The next three steps, which are the subject of this presentation, involve image display, distribution, and storage. Clinical requirements and associated cost considerations for these three steps are listed below: Image display: (1) Image quality equal to film, with DICOM format, lossless compression, image processing, desktop PC-based with color monitor, and physician-friendly imaging software; (2) Performance specifications include: acquire 30 frames/sec; replay 15 frames/sec; access to file server 5 seconds, and to archive 5 minutes; (3) Compatibility of image file, transmission, and processing formats; (4) Image manipulation: brightness, contrast, gray scale, zoom, biplane display, and quantification; (5) User-friendly control of image review. Image distribution: (1) Standard IP-based network between cardiac catheterization laboratories, file server, long-term archive, review stations, and remote sites; (2) Non-proprietary formats; (3) Bidirectional distribution. Image storage: (1) CD-ROM vs disk vs tape; (2) Verification of data integrity; (3) User-designated storage capacity for catheterization laboratory, file server, long-term archive. Costs: (1) Image acquisition equipment, file server, long-term archive; (2) Network infrastructure; (3) Review stations and software; (4) Maintenance and administration; (5) Future upgrades and expansion; (6) Personnel.

With the advent of the new Millennium, Picture Archive and Communications System (PACS) technology has matured to levels sufficient to support open systems based, regional implementations. This shifts the site-centric PACS paradigm into broader scale, impacting facilities, workflow, business plans and ultimately patient care on a regional basis. Prudent and effective management of a regional implementation is critical to overall project success based upon a number of competing influences fundamental to the PACS including network infrastructure, clinical workflow, acquisition modalities, planning documentation, site preparation, acceptance testing, project communication, interface integration issues, etc. Risk mitigation is possible by understanding and managing the interrelationships of these influences through a phased approach with embedded management controls. The overall phases of regional implementation are not unlike site-centric implementations, consisting of Discovery, Planning, Preparation, Installation; Acceptance and Warranty/Maintenance; however, details which manifest over time are what provide significant management challenges. When balanced using a culturally reinforced policy of open, frequent and hands-on communication, regional PACS projects can be successfully implemented maintaining budget, schedule and scope thresholds.

We used 3D modeling techniques to design and evaluate the ergonomics of diagnostic workstation and radiology reading room in the planning phase of building a new hospital at UCLA. Given serious space limitations, the challenge was to provide more optimal working environment for radiologists in a crowded and busy environment. A particular attention was given to flexibility, lighting condition and noise reduction in rooms shared by multiple users performing diagnostic tasks as well as regular clinical conferences. Re-engineering workspace ergonomics rely on the integration of new technologies, custom designed cabinets, indirect lighting, sound-absorbent partitioning and geometric arrangement of workstations to allow better privacy while optimizing space occupation. Innovations included adjustable flat monitors, integration of videoconferencing and voice recognition, control monitor and retractable keyboard for optimal space utilization. An overhead compartment protecting the monitors from ambient light is also used as accessory lightbox and rear-view projection screen for conferences.

For the next generation integrated information systems for health care applications, more emphasis has to be put on systems which, by design, support the reduction of cost, the increase inefficiency and the improvement of the quality of services. A substantial contribution to this will be the modeling. optimization, automation and enactment of processes in health care institutions. One of the perceived key success factors for the system integration of processes will be the application of workflow management, with workflow management systems as key technology components. In this paper we address workflow management in radiology. We focus on an important aspect of workflow management, the generation and handling of worklists, which provide workflow participants automatically with work items that reflect tasks to be performed. The display of worklists and the functions associated with work items are the visible part for the end-users of an information system using a workflow management approach. Appropriate worklist design and implementation will influence user friendliness of a system and will largely influence work efficiency. Technically, in current imaging department information system environments (modality-PACS-RIS installations), a data-driven approach has been taken: Worklist -- if present at all -- are generated from filtered views on application data bases. In a future workflow-based approach, worklists will be generated by autonomous workflow services based on explicit process models and organizational models. This process-oriented approach will provide us with an integral view of entire health care processes or sub- processes. The paper describes the basic mechanisms of this approach and summarizes its benefits.

User-centered design is a critical step in the product development cycle. It is an iterative process consisting of product design, implementation, and evaluation stages. Industry-standard usability metrics were employed to evaluate two sequential versions of commercial Picture Archiving and Communications System (PACS) workstation software as part of this process. They were evaluated 6 months apart by five radiologists with varying PACS experience. All radiologists were naive to the specific workstation tested. After a brief workstation overview, they were videotaped as they completed scenarios that closely simulated typical radiological practice. Each scenario consisted of various task categories. The task duration, nature and number of errors, help requests, and operator's manual consultations were recorded. After evaluating the first software version, areas for improvement were identified and the application design modified. An unexpected result was the rewriting of the software manual to be task- and process-based rather than feature-based. Testing of the second version revealed a 22% improvement in performance time and 30% decrease in the number of errors compared to the first. Usability testing objectively identifies areas for improvement in the PACS workstation software. Additionally, it provides quantitative measures that may be used to prioritize and suggest future design efforts. Performing this evaluation as early as possible results in the rapid evolution of an application that will maximize radiologists' productivity and satisfaction.

A study of timings of different events from the scheduling of an Emergency Department (ED) examination to the final reporting of it and review by the ED physician showed some expected and unexpected findings. Both computed radiography (CR) on film and CR using PACS were studied. The move of daytime reading of ED radiographs out of the Radiology reading area in the ED to a reading room in Radiology lengthened the time from when the request was sent to the time when the images were reviewed by the ED physician (1.02 hours to 1.29 hours). Despite anecdotal reports of increased reading time at workstations, the radiologists' use of PACS for reading ED radiographs resulted in a slight improvement in the time between the examination completion and report dictation (0.43 hours to 0.3 hours). Recently, we have found that there may be a workload effect on this time and this is presently being analyzed. The time from the sending of the request for an examination to the first review of the images by the ED physician was shortened with implementation of a PACS workstation in the clinical area of the ED (1.35 hours to 0.92 hours). A surprising finding was the impact the change to PACS had on the time between sending the request and the technologist's completion of the requested examination. The time increased with PACS from 0.45 hours for film-based CR to 0.8 hours for PACS. Several studies are ongoing to determine the causes of this increase.

Efforts to develop Picture Archiving and Communications Systems (PACS) for the last ten years have concentrated mainly on developing systems for primary interpretation of digital radiological images. Much less attention has been paid to the clinical aspects of the radiology process. Clinical radiology services are an important component of the overall care delivery process, providing information and consultation services to referring physicians, the customers of radiology, in a timely fashion to aid in care decisions. Information management systems (IMS) are playing an increasingly central role in the care delivery process. No suitable commercial PACS or IMS products were available that could effectively provide for the requirements of the clinicians. We endeavored to fill this void at our institution by developing a system to deliver images and text reports electronically on-demand to the referring physicians. This system has evolved substantially since initial deployment eight years ago. As new technologies become available they are evaluated and integrated as appropriate to improve system performance and manageability. Not surprisingly, the internet and World Wide Web (WWW) technology has had the greatest impact on system design in recent years. Additional features have been added over time to provide services for teleradiology, teaching, and research needs. We also discovered that these value-added services give us a competitive edge in attracting new business to our department. Commercial web-based products are now becoming available which do a satisfactory job of providing many of these clinical services. These products are evaluated for integration into our system as they mature. The result is a system that impacts positively on patient care.

A key current objective in Medical Informatics is to impose structure on collections of healthcare data recorded in electronic form. A relevant example is the DICOM Structured Reporting (SR) data structure. Appropriate presentation of image and related data is essential for effective communication of information between clinicians. The effective use of display screens for clinical viewing of image and related data, within the imaging service department and in the broader domain, depends on the availability of means to ensure consistent presentation on different systems. Whilst some users, such as reporting clinicians, will need full control over selection of presentation content, layout and rendering parameters, others may be restricted to viewing data as originally prepared. In order to support this, generally accepted data structures are required that allow the specification of presentation details for medical image data, graphics data and text data. The implementation options for supporting the identified needs are discussed, including the scope for using XML to carry the structures and to support an open presentation model for use throughout all healthcare domains.

A web-based video transmission of images from CT and MRI consoles was implemented in an Intranet environment for real- time monitoring of ongoing procedures. Images captured from the consoles are compressed to video resolution and broadcasted through a web server. When called upon, the attending radiologists can view these live images on any computer within the secured Intranet network. With adequate compression, these images can be displayed simultaneously in different locations at a rate of 2 to 5 images/sec through standard LAN. The quality of the images being insufficient for diagnostic purposes, our users survey showed that they were suitable for supervising a procedure, positioning the imaging slices and for routine quality checking before completion of a study. The system was implemented at UCLA to monitor 9 CTs and 6 MRIs distributed in 4 buildings. This system significantly improved the radiologists productivity by saving precious time spent in trips between reading rooms and examination rooms. It also improved patient throughput by reducing the waiting time for the radiologists to come to check a study before moving the patient from the scanner.

As healthcare moves towards a completely digital, multimedia environment there is an opportunity to provide for cost- effective, highly distributed physician access to clinical information including radiology-based imaging. In order to address this opportunity a Universal Clinical Desktop (UCD) system was developed. A UCD provides a single point of entry into an integrated view of all types of clinical data available within a network of disparate healthcare information systems. In order to explore the application of a UCD in a hospital environment, a pilot study was established with the University of California Davis Medical Center using technology from Trilix Information Systems. Within this pilot environment the information systems integrated under the UCD include a radiology information system (RIS), a picture archive and communication system (PACS) and a laboratory information system (LIS).

In medical imaging practice, images and reports often need be reviewed and edited from many locations. We have designed and implemented a Java-based Remote Viewing and Reporting System (JaRRViS) for a nuclear medicine department, which is deployed as a web service, at the fraction of the cost dedicated PACS systems. The system can be extended to other imaging modalities. JaRRViS interfaces to the clinical patient databases of imaging workstations. Specialized nuclear medicine applets support interactive displays of data such as 3-D gated SPECT with all the necessary options such as cine, filtering, dynamic lookup tables, and reorientation. The reporting module is implemented as a separate applet using Java Foundation Classes (JFC) Swing Editor Kit and allows composition of multimedia reports after selection and annotation of appropriate images. The reports are stored on the server in the HTML format. JaRRViS uses Java Servlets for the preparation and storage of final reports. The http links to the reports or to the patient's raw images with applets can be obtained from JaRRViS by any Hospital Information System (HIS) via standard queries. Such links can be sent via e-mail or included as text fields in any HIS database, providing direct access to the patient reports and images via standard web browsers.

PACS usually comes as an integrated solution consisting of an archive, a communications module, and viewers. The DICOM protocol is used for inter operability between the archive, modalities and other viewers. We claim that the inter- operability between the viewer and the archive should be optimized for price/performance in a way that cannot be fully exploited by the DICOM protocol. For instance, the archive may use high performance data-compression techniques that need not be part of the DICOM standard. In other cases when data is stored off-line (on tapes or MO) and has to be retrieved to online storage, DICOM does not provide a means to identify this state. In this paper we make a position statement seeking additional flexibility and more possibilities for inter- operability between viewers and archives than is available via DICOM alone. In fact, we are interested to define an API (Application Program Interface), using the Java language environment. This approach is based on accumulative experience in the Java community that shows the feasibility of this concept. We call this proposal JDAPI for Java DICOM API, since the DICOM data model is reflected within. Java is one of the most important modern programming languages for rapid application development. Java offers many advantages for this purpose, such as a very convenient development environment, and a very rich set of standard packages. Working under a Java Virtual Machine (JVM) turns Java into one of the most portable environments in existence today. The most important advantage of our proposal in defining a set of Java interfaces, is to allow an independent development of the viewer and of the archive. The viewer component is considered an application for the interface, which works on top of an implementation of the interface. The implementation is a provider of access methods to a particular (DICOM modeled) archive. Vendors who specialize in writing viewers, will not need to worry about incorporating DICOM protocols and a local (or memory) archive (SCU) into the viewer. Vendors who specialize in archives, will not need to worry about user interfaces. With this API each vendor will have the freedom to develop its part of the system and be sure it will work on any complimentary viewer.

As Picture Archiving and Communications Systems (PACS) implementations become more widespread, the management of deploying large, multi-facility PACS will become a more frequent occurrence. The tools and usability of the World Wide Web to disseminate project management information obviates time, distance, participant availability, and data format constraints, allowing for the effective collection and dissemination of PACS planning, implementation information, for a potentially limitless number of concurrent PACS sites. This paper will speak to tools, such as (1) a topic specific discussion board, (2) a 'restricted' Intranet, within a 'project' Intranet. We will also discuss project specific methods currently in use in a leading edge, regional PACS implementation concerning the sharing of project schedules, physical drawings, images of implementations, site-specific data, point of contacts lists, project milestones, and a general project overview. The individual benefits realized for the end user from each tool will also be covered. These details will be presented, balanced with a spotlight on communication as a critical component of any project management undertaking. Using today's technology, the web arguably provides the most cost and resource effective vehicle to facilitate the broad based, interactive sharing of project information.

The purpose of this paper is to introduce a new and important conceptual framework of software design for the medical imaging community using design patterns. Use cases are created to summarize operational scenarios of clinicians using the system to complete certain tasks such as image segmentation. During design the Unified Modeling Language is used to translate the use cases into modeling diagrams that describe how the system functions. Next, design patterns are applied to build models that describe how software components interoperate to deliver that functionality. The software components are implemented using the Java language, CORBA architecture, and other web technologies. The biomedical image information system is used in epilepsy neurosurgical planning and diagnosis. This article proposes the use of proven software design models for solving medical imaging informatics design problems. Design patterns provide an excellent vehicle to leverage design solutions that have worked in the past to solve the problems we face in building user-friendly, reliable, and efficient information systems. This work introduces this new technology for building increasing complex medical image information systems. The rigorous application of software design techniques is essential in building information systems that are easy to use, rich in functionality, maintainable, reliable, and updatable.

As PACS implementations increase during the new millennium, the need to plan and execute the movement of a live PACS from an existing facility into a replacement hospital increases. Such an undertaking should support not only the physical movement of the existing PACS but also the continuous support of clinical radiology operations throughout the transition period. This paper will describe two successful transitions of live PACS into newly constructed replacement hospitals. In 1994 the Brooke Army Medical Center transitioned into a newly constructed 450-bed facility in San Antonio Texas. In 1999 a similar movement of the Elmendorf Air Force Medical Center was successful accomplished in Anchorage Alaska. Both moves provided continuous operations of the Radiology Department and full clinical services in the old facilities in a near filmless mode while fully supporting the simultaneous installation and testing of new PACS components and PACS-to- modality interfaces in the new facilities. The process also included the migration of the image archives and acceptance testing of the final installation. While the exact migration process must differ, depending on the PACS architecture and the facility transition plans, these two examples provide a general framework for the issues and strategies for such a move.

This paper describes the initial phases and configuration of the Picture Archive and Communication System (PACS) deployed at Northwestern Memorial Hospital. The primary goals of the project were to improve service to patients, improve service to referring physicians, and improve the process of radiology. Secondary goals were to enhance the academic mission, and modernize institutional information systems. The system consists of a large number of heterogeneous imaging modalities sending imaging studies via DICOM to a GE medical Systems PathSpeed PACS. The radiology department workflow is briefly described. The system is currently storing approximately 140,000 studies and over 5 million images, growing by approximately 600 studies and 25,000 images per day. Data reflecting use of the short term and long term storage is provided.

Few information systems today offer a clear and flexible means to define and manage the automated part of radiology processes. None of them provide a coherent and scalable architecture that can easily cope with heterogeneity and inevitable local adaptation of applications. Most importantly, they often lack a model that can integrate clinical and administrative information to aid better decisions in managing resources, optimizing operations, and improving productivity. Digital radiology enterprises require cost-effective solutions to deliver information to the right person in the right place and at the right time. We propose a new architecture of image information management systems for digital radiology enterprises. Such a system is based on the emerging technologies in workflow management, distributed object computing, and Java and Web techniques, as well as Philips' domain knowledge in radiology operations. Our design adapts the approach of '4+1' architectural view. In this new architecture, PACS and RIS will become one while the user interaction can be automated by customized workflow process. Clinical service applications are implemented as active components. They can be reasonably substituted by applications of local adaptations and can be multiplied for fault tolerance and load balancing. Furthermore, it will provide powerful query and statistical functions for managing resources and improving productivity in real time. This work will lead to a new direction of image information management in the next millennium. We will illustrate the innovative design with implemented examples of a working prototype.

To establish generalized method of quantitative measurement of clinical effectiveness of HIS/RIS, a method of comparison between pre/post operation of a system and between different systems operated in different hospitals was proposed. A generalized method for calculation of effectiveness index by score functions was developed. The results of measurement and calculation were applied to look for the timing of version up of the systems and also will be applied to grasp the effectiveness of revised systems. We have measured clinical effectiveness quantitatively along the method of technology assessment of HIS/RIS in Osaka University since 1993. Objects of measurement in HIS were time study such as consulting time, machine operation time, machine operation time with conversation between a physician and his patient and so on. And objects of measurement in RIS were reporting time for image diagnosis, writing time for a report and number of characters written in a radiological report and so on. Actual numerical value of index was calculated according to the developed score function and variables measured in 1998 and 1999 for HIS, and also according to the score function and variables measured in 1993 before RIS operation and after RIS operation in 1994, 1995, 1996, 1998 and 1999. The measurement and calculation will be carried out in other hospitals at large and the indices will be compared between hospitals in terms of system characteristics.

Yonsei University Medical Center (YUMC) in Seoul, Korea is 114 years old and 1,582 beds in Shinchon Severance hospital in main university campus and 746 beds in affiliated Youngdong Severance hospital which is 20 miles away from the main campus. The dental hospital in main campus is also included in a full-PACS system. The numbers of exams/year for main, affiliated, and dental hospitals are approximately 558,000, 365,000, and 181,000, respectively. Since 1997, a Mini-PACS with 3xMRI, 2xDSI, and 2xCT in Shinchon Severance hospital has been operating to archive the digital data and to view them with DICOM viewer PiView^TM. An archiving system with 2xCT and 2xMRI in Youngdong Severance has been operating to archive the digital data. We are now designing a large-scale full-PACS for YUMC with experiences of running a mini-PACS for 3 years. The 11xUS, 7xEndoscopy, 7xCR, 3xSPECT, 1xPET, 1xCT simulator, and digital camera based patient database in the Dept. of radiation oncology in Shinchon Severance hospital will be connected to an archiving server system through modality interface gateway. The 3xCR, 2xDSA, 2xFD, 5xUS, 3xEndoscopy in Youngdong Severance hospital will be connected to the main archiving system. The 1xCT, 10xIntraoral X-ray unit DR, 4xPanoramic&cephalometric unit DR, 1xTranscranial CR, 1xScanora X-ray unit CR, 1xSectography CR in dental hospital will be connected to archiving server system through modality interface gateway. The estimated amount of data for Shinchon severance, Youngdong severance, and dental hospitals per year are 11.55TB, 5.88TB, and 0.96TB, respectively. The current mini-PACS server includes 54 GB RAID, 520 GB DLT with SUN Spectra^TM server. The main server in Shinchon Severance hospital needs to be upgraded to 600GB RAID for 30 days and 10TB ODJ or DLT for the first two years. Youngdong Severance hospital needs to be installed a main server with 600GB RAID for > 30 days and 10TB ODJ or DLT for > 2 years. The interface between HIS/RIS and PACS needs to be developed using a PACS broker. YUMC has successfully been operating the Mini- PACS for last 3 years and now expanding to a full-PACS for 558,000 exams/year in Shinchon Severance, 365,000 exams/year in affiliated Youngdong Severance, and 181,000 exams/year in dental hospitals.

The medicolegal necessity of privacy, security and confidentiality was the aim of the attempt to develop a secure teleradiology workflow between the telepartners -- radiologist and the referring physician. To avoid the lack of dataprotection and datasecurity we introduced biometric fingerprint scanners in combination with smart cards to identify the teleradiology partners and communicated over an encrypted TCP/IP satellite link between Innsbruck and Reutte. We used an asymmetric kryptography method to guarantee authentification, integrity of the data-packages and confidentiality of the medical data. It was necessary to use a biometric feature to avoid a case of mistaken identity of persons, who wanted access to the system. Only an invariable electronical identification allowed a legal liability to the final report and only a secure dataconnection allowed the exchange of sensible medical data between different partners of Health Care Networks. In our study we selected the user friendly combination of a smart card and a biometric fingerprint technique, called Skymed^TM Double Guard Secure Keyboard (Agfa-Gevaert) to confirm identities and log into the imaging workstations and the electronic patient record. We examined the interoperability of the used software with the existing platforms. Only the WIN-XX operating systems could be protected at the time of our study.

We evaluated the feasibility of fingerprint-scanners in combination with smart cards for personal identification and transmission of encrypted TCP/IP-data-packages via satellite between the university-hospital of Innsbruck and the rural hospital of Reutte. The aim of our study was the proof of the userfriendliness of the Skymed^TM technology for security purpose in teleradiology. We examined the time of the personal identification process, the time for the necessary training and the personal satisfaction. The images were sent from the local PACS in Reutte via a Data-Encryption-and-Transmission- Box via satellite from Reutte to Innsbruck. We used an asymmetric bandwidth of 512 kbit/s from Reutte to Innsbruck and 128 kbit/s in the opposite direction. Window NT 4.0- operating PCs were used for the electronical patient record, the medical inquiry of the referring physician and the final report of the radiologist. The images were reported on an UNIX-PACS viewing station. After identification through fingerprint-scanners in combination with the smart card the radiologist was able to open the electronic patient record (EPR) from Reutte and sign with his digital signature his confirmed final report before it was send back to Reutte. The used security technology enables encrypted communication over a WAN, which fulfill data-protection.

The specification of security features of the DICOM (digital imaging and communication in medicine) standard is not clear where encryption and decryption are concerned. In the age of digital medicine, a growing need for secure transfer and storage of patient data is obvious. In medical science, the design of a PACS (picture archiving and communication system) is essential for storing digital images. This paper describes an alternative method of integrating encryption as a DICOM- conform mechanism in a PACS and via a DICOM-conform directory service in a HIS (hospital information system)/RIS (radiological information system). It is useful to integrate these systems in order to be able to merge existing patient data with DICOM images. The DICOM supplement SR (structured reporting) is used for encryption and as an interface- specification for databases. SR also allows the definition of private coding schemes. It is possible to integrate security in a PACS by using one, private, coding scheme for encryption and a different coding scheme for decryption. The interface to the databases is a directory service that uses its attributes to store orders from databases and which retrieves orders for the databases. This method makes the construction of a secure HIPACS (hospital integrated picture archiving system) possible.

Tele-medical imaging applications require low cost, and high- speed backbone wide area networks (WAN) to carry large amount of imaging data for rapid turn around interpretation. Current low cost commercially available WAN is too slow for medical imaging applications, while high speed WAN is too costly. Internet2 or Next Generation Internet (NGI) emerges as a good candidate for tele-medical imaging applications because of its high speed and low cost. This paper describes the beginning of a three-year project on exploring the possibility of using NGI for medical imaging applications. Connectivity of a private ATM to the Internet2 is first discussed, followed by methods of preserving data integrity in the public networks. Two medical imaging applications in telemammography and interactive teaching of breast imaging are presented. A preliminary plan on methods of evaluating the performance of the NGI is followed.

Lockheed Martin's Intelligent Library System (ILS)^TM imagery management solution was originally developed for users and distributors of Earth imagery emanating from commercial remote sensing satellites or aircraft. The product is a total hardware and software solution comprised of two main components: SmartArchiver^TM digital asset management system and SmartAnalyst^TM imagery exploration tools. While investigating the latest technologies and developing Intelligent Library System (ILS)^TM as a state-of-the-art system, we realized SmartArchiver systems offered robust functionality not available elsewhere for handling large medical imagery files. The SmartArchiver system's features answer the following needs of medical imagery handling: smooth handling of large individual imagery files; easy access to specific imagery or types of imagery; cost-effective storage of historical data and protection of imagery over time; ability to grow an archive to thousands of terabytes; distribution from a central archive to multiple viewing sites; varying levels of resolutions requirements at the viewing stations; strict multi-level security adherence; and automated workflow management. In this paper we detail the features of the system and how they apply to medical imagery management. We also describe how a medical application can be served by the SmartArchiver asset management system.

In this paper we present a semantic content representation scheme and the associated techniques for supporting (1) query by image examples or by natural language in a histological image database and (2) automatic annotation generation for images through image semantic analysis. In this research, various types of query are analyzed by either a semantic analyzer or a natural language analyzer to extract high level concepts and histological information, which are subsequently converted into an internal semantic content representation structure code-named 'Papillon.' Papillon serves not only as an intermediate representation scheme but also stores the semantic content of the image that will be used to match against the semantic index structure within the image database during query processing. During the image database population phase, all images that are going to be put into the database will go through the same processing so that every image would have its semantic content represented by a Papillon structure. Since the Papillon structure for an image contains high level semantic information of the image, it forms the basis of the technique that automatically generates textual annotation for the input images. Papillon bridges the gap between different media in the database, allows complicated intelligent browsing to be carried out efficiently, and also provides a well- defined semantic content representation scheme for different content processing engines developed for content-based retrieval.

While Picture Archiving and Communicating System project is underway through out the western countries, China is making a revolutionary advance in digital medical record. Hospitals in China have made their first steps toward implementation of PACS. Due to the ever-increasing amount of medical image data, a completed archive server is of great need as the base of filmless radiology, a cost effective, high performance digital archive system will remain as the most essential and challenging part of PACS. However there is an inevitable and inherent dilemma in those hospitals in the developing countries like China -- limited amount of development funds. So we are urged to design a low cost but efficient image archive system to cater to the expectation of the hospital. This paper describes a high capacity PACS image archive system model that is developed with rather low cost. To build a reliable and flexible image archive system involves a number of factors such as system capacity requirement, storage and retrieval performance and cost saving etc. We have undertaken the hierarchy image storage mechanism. Judicious image dispatch is employed to meet the goal of timely image retrieval. The whole design can be divided into two parts, one is Scheduled Image Flow Service (SIFS) whose purpose is to periodically backup, archive and pre-fetch image, the other one is Online Image Retrieval Service (OIRS) to provide quick access to the online and nearline images through the network interface. Automatic image transfer is realized between different storage tiers with high level of control. All the procedure is highly automatic except the manually depositing and undepositing off-line optical disks. System evaluations on random retrieval time are presented to show the effect of image location. The concept of image tiered storage will largely reduce the cost of storage. Real-time response to the retrieval demand can send wanted images to a radiologist in a reasonable time. We have done some beneficial trials on how to implement large scale and high performance PACS image archive system under the condition of short of fund. At the same time, according to the characteristic of those storage media whose price will drop down around the clock. The archive system should be capable of being scaled to higher level smoothly. When the purchase of new storage device can be guaranteed, new component will be integrated flexibly and easily. With the advent of digital era, digital medical record will become a big trend of information management in those developing countries. Our work will be a great impetus to the substitute of optical jukebox for the conventional storage medium -- film.

Medical imaging's technological evolution in the next century will continue to include Picture Archive and Communication Systems (PACS) and teleradiology. It is difficult to predict radiology's future in the new millennium with both computed radiography and direct digital capture competing as the primary image acquisition methods for routine radiography. Changes in Computed Axial Tomography (CT) and Magnetic Resonance Imaging (MRI) continue to amaze the healthcare community. No matter how the acquisition, display, and archive functions change, Quality Control (QC) of the radiographic imaging chain will remain an important step in the imaging process. The Task Allocation Chart (TAC) is a tool that can be used in a medical facility's QC process to indicate the testing responsibilities of the image stakeholders and the medical informatics department. The TAC shows a grid of equipment to be serviced, tasks to be performed, and the organization assigned to perform each task. Additionally, skills, tasks, time, and references for each task can be provided. QC of the PACS must be stressed as a primary element of a PACS' implementation. The TAC can be used to clarify responsibilities during warranty and paid maintenance periods. Establishing a TAC a part of a PACS implementation has a positive affect on patient care and clinical acceptance.

Purpose: Data security becomes an important issue in telemedicine when medical information is transmitted over wide area network. Generally, security is characterized in terms of privacy, authenticity and integrity of digital data. We present a method here which can meet the requirements of privacy, authenticity, and integrity for archiving and transmitting of sectional image such as CT, MR. Methods: The method is described as follows: firstly, image segmentation was done and some patient information was read from image DICOM header. Second, a digital signature for the segmented image was produced using the image sender's private key. Afterwards, the digital signature and patient information were concatenated and embedded into the background area of the image. Finally, the whole image was encrypted to form a digital envelope using the receiver's public key. Results: (1) The image can only be decrypted and read by authorized user who own the private key of the receiving site. (2) The authenticity and integrity can be tested by signature verification. Conclusions: The preliminary results demonstrate that the method we presented here is an effective method for secure archiving and transmitting for sectional medical images.

The purpose of this project is to study the feasibility of remotely managing mammography examinations in real time. To do so, the remotely located expert mammo-grapher needs to view newly generated images and communicate with on-site technologist before a patient leaves the examination room. A telemammography test-bed has been setup between two UC San Francisco clinical facilities. In the current system, the overhead of network and disk I/O delays the image availability at the remote expert workstation. We modified the communication software to enable memory-to-memory image transfer. Besides, we optimized the data flow between the hosts to enable images be directly transmitted from the digital mammography console to the remote display workstation. In this paper, we present the implementation of fast telemanagement in digital mammography environments. The preliminary results show the feasibility of adding telemanagement protocol into the current telemammography system.

For efficient storing of medical motion images such as digital cine angiography, optimized compression ratio for motion image and efficient mass storage media is required. We have many selections to compressing motion image. MPEG-2 is one of de facto standard in motion image compression techniques. In order to find out optimized compression ratio using MPEG-2, both subjective evaluation and objective evaluation were carried out. These evaluation methods are based on severity decision of vessel stenosis for coronary vessel. From these results, we found optimized compression ratio using MPEG-2 is 1:80. In case of employing DVD-RAM media as storage media of medical motion images, the cost for storage is slightly more expensive than in case of employing CD-R media.

Traditionally, to guarantee the network performance of medical image data transmission, imaging traffic was isolated on a separate network. Organizations are depending on a new generation of multi-purpose networks to transport both normal information and image traffic as they expand access to images throughout the enterprise. These organi want to leverage their existing infrastructure for imaging traffic, but are not willing to accept degradations in overall network performance. To guarantee 'on demand' network performance for image transmissions anywhere at any time, networks need to be designed with the ability to 'carve out' bandwidth for specific applications and to minimize the chances of network failures. This paper will present the methodology Cincinnati Children's Hospital Medical Center (CHMC) used to enhance the physical and logical network design of the existing hospital network to guarantee a class of service for imaging traffic. PACS network designs should utilize the existing enterprise local area network i.e. (LAN) infrastructure where appropriate. Logical separation or segmentation provides the application independence from other clinical and administrative applications as required, ensuring bandwidth and service availability.

Kinetic MRI images has been developed and often applied to the diagnosis of soft tissues. The diagnosis of the temporomandibular joint seemed to be one of the typical application fields and has been already clinically performed in some hospitals. Kinetic MRI images cannot be dealt with by DICOM systems, since the information elements and transfer syntax has not been defined yet. We tried to define them and examined its performances. Several objects of temporomandibular joint kinetic MRI images in Quick TIME format were created using the newly defined information elements. The objects were transferred and stored to a DICOM image server using CTN software. The stored images were successfully reconstructed and replayed. The outline of the newly defined information elements, the procedures for making and reconstruction of the objects were discussed in this paper.

With the proliferation of Picture Archiving and Communications Systems (PACS) throughout the U.S. Healthcare System, there is an immense need for alternative approaches to maintenance support of PACS systems. One method of cost reduction is through the implementation of regional maintenance programs. While many PACS vendors are willing to negotiate various forms of shared service arrangements, multi-facility and regional negotiations are rarely implemented. This paper will present such an approach by describing a four step process: (1) Identify maintenance tasks across the entire region/enterprise; (2) Identify maintenance resources within the region/enterprise that can be assigned against those tasks; (3) Identify vendor unique resources that must be added to regional/enterprise resources to complete the required coverage of maintenance tasks; and (4) Negotiate with all member sites of the region/enterprise and the vendor for the assignment of resources against all maintenance tasks. Additionally, these steps will be balanced through identification of the principal tradeoffs tied to maintenance resourcing, namely: quality, speed and cost. If this approach is implemented, it presents a mechanism for achieving maintenance service cost reductions, while supporting clinical operations, through the benefits of economies of scale and collective bargaining.

Inductive Modeling Techniques (IMT) in a stand alone, distributed Picture Archiving and Communication System (PACS) or telemedicine environment can be utilized to monitor SNMP (Simple Network Management Protocol) enabled devices such as network switches, servers or workstations. A comprehensive approach using IMT is presented across the stages of the PACS lifecycle: Pre-PACS, Implementation, and Clinical Use. At each stage of the cycle, the results of IMT can be utilized to assist in assessing and forecasting future system loading. This loading represents a clinical trend analysis equating to the clinical workflow and delivery of services. Specific attention is directed to an understanding and thorough depiction of IMT methodology, focusing on the use of SNMP, the Management Information Base (MIB), and the data stream output that is mapped and placed in an object-oriented database and made available for web-based, real time, in-depth viewing and/or analysis. A thorough description of these outputs is presented, spotlighting potential report applications such as system failures; existing system, CPU, workstation, server and LAN/WAN link utilization; packet rates; application isolation; notification of system alarms; fault isolation; high/low bandwidth users; and data transfer rates. These types of data are increasingly required for programming LAN/WAN upgrades as digital imaging and PACS are implemented.

To practice mammography diagnosis effectively, radiologists expect convenient access to well-organized and authoritative mammography related information, especially when there is case in question. The purpose of this study is to build infrastructural diagnosis support by incorporating various clinical information into a digital mammography case library, and allow user to search the library based on mammographic findings. The digital mammography case library has a three- tier architecture: (1) Back-end mammography databases integrate multimedia clinical information from various operational systems, including RIS and PACS. Cases are stored in a finding index database powered by an object-relational database with finding-coded reports, which are modeled around the ACR BI-RADS (American College of Radiology, Breast Imaging Report and Data System) standard. (2) The middle-end application controllers process application logic, such as user authorization, HTTP request handling, database connection and dynamic HTML page generation. (3) Web-based user interface is developed for authorized Intranet personnel to formulate query based on radiological finding (such as mass, calcification and architectural distortion), shape and assessment, using ACR BI-RADS specified lexicon. The case library so far has 103 cases selected from over 800 digital mammography studies carried out at the Mt. Zion hospital, UCSF, during an on-going digital telemammography project. We believe that an Intranet based digital mammography case library with mammographic finding search capability facilitates continuous medical education and online decision support, by providing exemplary study to compare with case in question.

We constructed a high-speed medical information network testbed, which is one of the largest testbeds in Japan, and applied it to practical medical checkups for the first time. The constructed testbed, which we call IMPACT, consists of a Super-High Definition Imaging system, a video conferencing system, a remote database system, and a 6 - 135 Mbps ATM network. The interconnected facilities include the School of Medicine in Keio University, a company's clinic, and an NTT R&D center, all in and around Tokyo. We applied IMPACT to the mass screening of the upper gastrointestinal (UGI) tract at the clinic. All 5419 radiographic images acquired at them clinic for 523 employees were digitized (2048 X 1698 X 12 bits) and transferred to a remote database in NTT. We then picked up about 50 images from five patients and sent them to nine radiological specialists at Keio University. The processing, which includes film digitization, image data transfer, and database registration, took 574 seconds per patient in average. The average reading time at Keio Univ. was 207 seconds. The overall processing time was estimated to be 781 seconds per patient. From these experimental results, we conclude that quasi-real time tele-medical checkups are possible with our prototype system.

In an ATM (Asynchronous Transfer Mode)-based PAC system, cell losses during the transmission might cause degradation on the quality of medical images. This in turn will affect the accuracy of the diagnosis. A three-step scheme to minimize the effect of cell losses on the quality of medical images is proposed in this paper. The first step is related to the medical imaging coding before it enters the network, in which, ROIs (Regions of Interest) of the medical imaging which are crucial to diagnosis are kept non-compressed and packetized with pixel-level inter-leaving. Non-compression can make the data of ROIs to be more robust to cell losses than any compression algorithms, while pixel-level inter-leaving is strong for bursty cell losses recovery combined with FEC (Forward Error Correction) at the receiver. The background part of the medical imaging will be compressed using fractal algorithm, which can get very high compression ratio to balance the large amount data of the ROIs. In the second step, the ROIs will be allocated the highest priority during transmission. While in the third step, FEC will be used to minimize the existed cell losses at the receiver. The balance and optimal of these three stages are discussed from the system-level point of view.

The Web browser is an excellent environment for the rapid development of an effective and inexpensive PACS viewer. In this paper we will share our experience in developing a browser-based viewer, from the inception and prototype stages to its current state of maturity. There are many operational advantages to a browser-based viewer, even when native viewers already exist in the system (with multiple and/or high resolution screens): (1) It can be used on existing personal workstations throughout the hospital. (2) It is easy to make the service available from physician's homes. (3) The viewer is extremely portable and platform independent. There is a wide variety of means available for implementing the browser- based viewer. Each file sent to the client by the server can perform some end-user or client/server interaction. These means range from HTML (for HyperText Markup Language) files, through Java Script, to Java applets. Some data types may also invoke plug-in code in the client, although this would reduce the portability of the viewer, it would provide the needed efficiency in critical places. On the server side the range of means is also very rich: (1) A set of files: html, Java Script, Java applets, etc. (2) Extensions of the server via cgi-bin programs, (3) Extensions of the server via servlets, (4) Any other helper application residing and working with the server to access the DICOM archive. The viewer architecture consists of two basic parts: The first part performs query and navigation through the DICOM archive image folders. The second part does the image access and display. While the first part deals with low data traffic, it involves many database transactions. The second part is simple as far as access transactions are concerned, but requires much more data traffic and display functions. Our web-based viewer has gone through three development stages characterized by the complexity of the means and tools employed on both client and server sides.

Real-time teleconsultation in radiology enables physicians to perform same-time consultation between remote peers, based on medical images. Since digital medical images are commonly viewed on PACS workstations, it is possible to use one of several methods for remote sharing of the computer screen. For instance, software products such as Microsoft NetMeeting, or IBM SameTime, can be used. However, the amount of image data transmitted can be very high, since even minute changes in an image window/level requires re-transmitting the entire image again and again. This is too inefficient. Looking for better methods, when restricting the problem to the use of same hardware and software of the same vendor, it is easier to develop a solution that employs a proprietary specialized protocol to coordinate the visualization process. Such is a solution that we developed, and which demonstrated an excellent performance advantage by transmitting only the graphical events between the machines, rather than the image pixels. Our solution did not inter-operate with other viewers. It worked only on X11/Motif systems, and only between compatible versions of the same viewer application. Our purpose in this paper is to enable inter-operability between viewers of different platforms, and different vendors. We distinguish three parts: Session control, audiovisual (multimedia) data exchange, and medical image sharing. We intend to deal only with the third component, assuming the use of existing standards for the first two parts. After a session between two or more parties is established, and optional audiovisual data channels are set, the medical consultation is considered as the coordinated exchange of medical image contents. Some requirements for the contents exchange protocol: In the first stage, the parties negotiate the actual set of capabilities to be used during the consultation, using a formal description of these capabilities. The capabilities that one station lacks over the other (such as specific image processing algorithms) can be 'borrowed.' In the second stage, when interaction starts, it should assume that the graphical user interface of the stations might be different, as well as working procedures. During the consultation, data is exchanged based on DICOM for the data model of medical image folders, and the data format of image objects.