Lewis E. Berman

Digital atlas for spinal x rays

At the National Library of Medicine we are developing a digital atlas to serve as a reference tool for the interpretation of cervical and lumbar spine x-rays. The atlas contains representative images for four grades of severity for cervical/lumbar spondylolisthesis. A prototype version of the atlas has been built using images for which expert rheumatologist readers reached exact agreement in grading. The atlas functionality includes the ability to display cervical and lumbar anatomy, display of single images or multiple simultaneous images, image processing functions, and capability to ad user-defined images to the atlas. Images are selected for display by the user specifying feature and grade. Currently, the atlas runs on a Sun SPARC workstation under the Solaris operating system. THe initial use of the atlas is to aid in reading a collection of 17,000 NHANES II digitized x-rays. The atlas may also be used as a general digital reference tool for the standardized interpretation of digital x-rays for osteoarthritis. We are investigating further development of the atlas to accommodate a wider set of images, to operate on multiple platforms, and to be accessible via the WWW.

A client/server system for internet access to biomedical text/image databanks

Internet access to mixed text/image databanks is finding application in the medical world. An example is a database of medical X-rays and associated data consisting of demographic, socioeconomic, physicians exam, medical laboratory and other information collected as part of a nationwide health survey conducted by the government. Another example is a collection of digitized cryosection images, CT and MR taken of cadavers as part of the National Library of Medicines Visible Human Project. In both cases, the challenge is to provide access to both the image and the associated text for a wide end user community to create atlases, conduct epidemiological studies, to develop image-specific algorithms for compression, enhancement and other types of image processing, among many other applications. The databanks mentioned above are being created in prototype form. This paper describes the prototype system developed for the archiving of the data and the client software to enable a broad range of end users to access the archive, retrieve text and image data, display the data and manipulate the images. System design considerations include; data organization in a relational database management system with object-oriented extensions; a hierarchical organization of the image data by different resolution levels for different user classes; client design based on common hardware and software platforms incorporating SQL search capability, X Window, Motif and TAE (a development environment supporting rapid prototyping and management of graphic-oriented user interfaces); potential to include ultra high resolution display monitors as a user option; intuitive user interface paradigm for building complex queries; and contrast enhancement, magnification and mensuration tools for better viewing by the user.

Application-level technique for faster transmission of large images on the internet

An application-level technique for improving the transmission rate of large files is described in this paper. Such techniques are important in areas such as telemedicine, where near-real-time delivery of large files such as digital images is a goal: end users may include specialist whose time is scarce and expensive, and timely access to the data may be necessary for effective clinical treatment. Faster delivery is also an enabling technology for accessing remote medial archives. In conventional TCP/IP transmission, data to be transmitted is sent down one logical communication channel. Our technique divided the data into segments; each segment is sent down its own channel, and the segments are reassembled into a copy of the original data at the receiving end. This technique has been implemented and tested in a client-server program using Berkeley Unix sockets, multiple independent process for channel control, and interprocess communication techniques to guarantee the receipt and correct reassembly of the transmitted data. Performance measurements have been made on several hundred Internet transmissions (including Arizona-to-Maryland transmissions) of 5-megabyte cervical x- ray images. Transmission time as a function of number of channels has been recorded, and a 3-fold improvement in transmission rate has been observed.

Design issues for a digital x-ray archive accessed over Internet

The design of an electronic archive of digitized images of thousands of xrays collected as part of nationwide health surveys has raised several issues related to user interface design, image presentation and image compression. The project involves developing an image archive implemented with an optical disk jukebox, and user workstations that allow Internet access to the images. This paper describes: the physical layout design of the workstation screens; desirable image processing functions contributing to better viewing and minimizing artifacts; interface design factors contributing to ease-of-use and speed of task completion; and work toward the selection of a suitable image compression technique.

Design considerations for wide-area distribution of digital x-ray images

The increasing backbone speeds of Wide Area Networks, along with the growing numbers of users of these networks, have created an opportunity for the development of remotely accessible and highly data-intensive digital libraries. The National Library of Medicine is building a prototype system for the storage of several thousand digital x-ray images, while providing remote access to these images across the Internet. This paper discusses the design factors analyzed for this system, and presents performance statistics collected. The design factors considered include: network protocol selection, endpoint tuning of protocol, image compression, and application data handling. Research toward application data handling includes plans to stage groups of images from an optical archive to memory for the efficient transmission of large numbers of images. To maximize image data transmission speed, experimental protocols are being studied as alternatives to TCP/IP. TCP overhead processing is being researched, and approaches to tuning TCP performance for transmission of large image files are being analyzed. To minimize the storage capacity required and to decrease transmission time, lossy compression techniques are being considered. Research is proceeding toward the selection of a compression technique and optimum compression ratio consistent with the image quality required to produce standardized readings.

Interactive selection of JPEG quantization tables for digital x-ray image compression

Selecting an appropriate quantization table for Joint Photographic Exploitation Group (JPEG) data compression of a class of images can be an arduous task. We have designed a graphical user interface to study the effects of quantization on compression ratio and the resulting image quality. The tool calculates several measures of the difference between the original and lossy compressed image. Some of these measures are entropy, mean square error, and normalized mean square error. These measures aid the user in selecting the optimal quantization values with respect to image fidelity and compression ratio for a particular class of images.

Public Health Informatics in the National Health and Nutrition Examination Survey

The National Health and Nutrition Examination Survey (NHANES) provides an example of the use of technology and systems to collect data simultaneously in geographically distinct locations and make available crucial data related to public health. Through the development and use of the Integrated Survey Information System (ISIS), NHANES connects field personnel, mobile examination centers, contractors, and the Centers for Disease Control and Prevention (CDC)/National Center for Health Statistics (NCHS) headquarters for a continuous flow of data in near real time. It also makes those data available in a usable form to researchers and analysts. This chapter provides an overview of the NHANES methodology, objectives, and goals. It also describes an application of public health informatics that is both innovative and highly functional.

Data storage and organization for a general-access x-ray image archive

Medical radiographs and associated data collected as part of a nationwide health survey in the U.S. are digitized and stored in an electronic archive accessible over the Internet. This paper describes the prototype system developed for the archiving of the data and the client software to enable a broad range of end users to access the archive, retrieve text and image data, display the data and manipulate the images.

Access to a digital x-ray archive over Internet

This paper describes a project involving the creation of an electronic archive of x ray images, and the development of geographically dispersed workstations that access the image store, retrieve the image files over Internet, and allow viewers to display, manipulate, enhance, and read the images.