Two-year clinical experience with a computed radiography system.
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Radiographic Image Enhancement↗
Biomedical subjects
B K Ho
Publications and source records attributed to B K Ho.
Picture archiving and communication systems (PACS) for radiological images: state of the art.
Implementation of a Picture Archiving and Communication System (PACS) is a system integration task and requires the knowledge of multidisciplinary fields. This paper reviews current PACS development with emphasis on radiological images. The following topics are covered: methods of image acquisition, image compression, storage, display, communication, and image database structure. Methods of implementation of PACS in a clinical environment as well as current operational PACS in hospitals are reviewed. A survey of private industry participating in PACS research and development are also given.
Hospital Information Systems↗
Radiological image compression using error-free irreversible two-dimensional direct-cosine-transform coding techniques.
Some error-free and irreversible two-dimensional direct-cosine-transform (2D-DCT) coding, image-compression techniques applied to radiological images are discussed in this paper. Run-length coding and Huffman coding are described, and examples are given for error-free image compression. In the case of irreversible 2D-DCT coding, the block-quantization technique and the full-frame bit-allocation (FFBA) technique are described. Error-free image compression can achieve a compression ratio from 2:1 to 3:1, whereas the irreversible 2D-DCT coding compression technique can, in general, achieve a much higher acceptable compression ratio. The currently available block-quantization hardware may lead to visible block artifacts at certain compression ratios, but FFBA may be employed with the same or higher compression ratios without generating such artifacts. An even higher compression ratio can be achieved if the image is compressed by using first FFBA and then Huffman coding. The disadvantages of FFBA are that it is sensitive to sharp edges and no hardware is available. This paper also describes the design of the FFBA technique.
Angiography↗
Picture archiving and communication systems in Japan.
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Humans↗
Liver disease associated with duck hepatitis B virus infection of domestic ducks.
The liver disease associated with duck hepatitis B viremia was investigated in naturally infected ducks from Chi-tung county in China and in both naturally and experimentally infected ducks from the United States. Liver and serum specimens of adult Chinese ducks were examined for duck hepatitis B virus (DHBV) DNA by dot and gel blot hybridization. DHBV was found in serum and (in episomal form only) in livers of 6 of 11 birds exhibiting various degrees of chronic hepatitis. In 1 bird with hepatocellular carcinoma, DHBV DNA was detected at the limit of assay sensitivity and in another not at all, contrasting with findings in humans and woodchucks. In work with California Pekin and Khaki Campbell ducks, known amounts of DHBV were injected into the egg 10 days before, or into ducklings 1 day after, hatching and the livers were examined 6 weeks later. The majority of the injected ducklings had viremia detectable by hybridization 1 or 2 weeks after injection. The presence but not the amount of viremia correlated with incidence and degree of hepatitis, determined under code. The most severe instances of hepatitis, all in Pekin ducks, resembled the hepatitis in adult Chinese ducks of Chi-tung county. Severe and moderate hepatitis were found only in indoor-caged injected animals with viremia and in some uninjected birds without viremia that had been kept in outdoor flocks. The latter hepatitis, as some hepatitis in adult Chinese ducks, may not be related to DHBV. Mild and insignificant hepatitis were also found in injected and noninjected ducklings, some of which had the vertically transmitted spontaneous viremia previously described. The good correlation of experimentally induced viremia with incidence and severity of hepatitis in the Pekin duckling provides a simple, rapid, and relatively inexpensive model to study the relation of lesions to hepatitis B family infection in nonprimates.
Animals↗
Automatic acquisition interfaces for computed radiography, CT, MR, US, and laser scanner.
Existing radiological imaging devices such as computed radiography (CR), computed tomography (CT), magnetic resonance imaging (MR), and ultrasound (US) systems generally do not have a direct digital interface to an external computer. Thus, special developments are necessary for their integration into a Picture Archiving and Communication System (PACS). The interface architecture and software models for performing automatic data acquisition from these devices as well as a CR plate scanner and a laser film digitizer are discussed based on their networking capabilities and the accessibility of internal data structures. The design approaches and operation efficiencies vary drastically depending on whether additional modules are needed, and whether the acquisition is performed on-line or off-line. In addition to the image data link, a complete acquisition interface includes polling of text patient information, image reformatting to the UCLA standard, and communication to the archival database.
Diagnostic Imaging↗
PACS workstation design.
This paper covers some of the recent concepts in designing a digital imaging workstation in a multimodality Picture Archiving and Communications Systems (PACS) network. A workstation in a multimodality PACS network must access, display, and analyze digital images from different imaging modalities with very different formats. The user interface should allow clinicians with minimal or no computer manipulation skills to use complex analysis tools. General guidelines of a graphics oriented user interface, based on windows and icons, are proposed. Instantaneous (real-time) response in the primary display and processing functions is vital for user acceptance. The hardware architectural concepts to achieve such a performance speed are described. Finally, a workstation environment conducive to comfortable viewing by the radiologists is discussed.
Computer Graphics↗
Implementation of a large-scale picture archiving and communication system.
This paper describes the implementation of a large-scale picture archiving and communication system (PACS) in a clinical environment. The system consists of a PACS infrastructure, composed of a PACS controller, a database management system, communication networks, and optical disk archive. It connects to three MR units, four CT scanners, three computed radiography systems, and two laser film digitizers. Seven display stations are on line 24 h/day, 7 days/wk in genitourinary radiology (2K), pediatric radiology in-patient (1K and 2K) and outpatient (2K), neuroradiology (2K), pediatric ICU (1K), coronary care unit (1K), and one laser film printing station. The PACS is integrated with the hospital information system and the radiology information system. The system has been in operation since February 1992. We have integrated this PACS as a clinical component in daily radiology practice. It archives an average of 2.0-gigabyte image data per workday. A 3-mo system performance of various components are tabulated. The deployment of this large-scale PACS signifies a milestone in our PACS research and development effort. Radiologists, fellows, residents, and clinicians use it for case review, conferences, and occasionally for primary diagnosis. With this large-scale PACS in place, it will allow us to investigate the two critical issues raised when PACS research first started 10 yrs ago: system performance and cost effectiveness between a digital-based and a film-based system.
Computer Communication Networks↗