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PubMed1995

Initial experience with asynchronous transfer mode for use in a medical imaging network.

Picture archiving and communication Systems (PACS) for medical imaging have always suffered from band-width limitations, throughput, and proprietary protocols. Commercially available local area networks have been hard pressed to meet the requirements of image transfer in a time consistent with patient-care needs. Recent technologic advances provide potential solutions to these constraints. Asynchronous transfer mode (ATM) provides the aggregate bandwidth and throughput that may be sufficient to satisfy the medical imaging community. Networks using prototype ATM technology have been available and commercial hardware is now becoming available. This report presents initial performance results of an ATM network and its suitability for use in a digital imaging network. Throughput of 10 Mbytes/sec was attained with Transmission Control Protocol/Internet Protocol using commercially available hardware.

Computer Communication Networks↗

PubMed1987

Digital image-management networks: problems in implementation.

The apparent advantages of a DIMS are often cited by those involved in medical information-management research. The promise of a high-speed electronic image-management system that could increase a department's patient throughput and improve patient care is most attractive. Every major manufacturer of medical imaging equipment has a group working to develop such systems. Many problems remain to be solved before such systems can be acquired, installed, and made operational. This paper has summarized the significant technical problems yet to be solved.

Archives↗

PubMed2003

YADCLAN: yet another digitally-controlled linear artificial neuron.

This paper updates the author's 1999 RMBS presentation on digitally controlled linear artificial neuron design. Each neuron is based on a standard operational amplifier having excitatory and inhibitory inputs, variable gain, an amplified linear analog output and an adjustable threshold comparator for digital output. This design employs a 1-wire serial network of digitally controlled potentiometers and resistors whose resistance values are set and read back under microprocessor supervision. This system embodies several unique and useful features, including: enhanced neuronal stability, dynamic reconfigurability and network extensibility. This artificial neuronal is being employed for feature extraction and pattern recognition in an advanced robotic application.

Amplifiers, Electronic↗

PubMed1991

Wide area networks for teleradiology.

Teleradiology networks transmit digital radiographic images from one location to another. These networks are wide area networks. Teleradiology networks are used for diagnostic purposes and preview tasks. Wide area networks for teleradiology use public service switching. The use of fiber optics networks provide reduced costs and increased flexibility. An example is presented that compares the cost of teleradiology networks.

Computer Communication Networks↗

PubMedDate not supplied

A hydrologic network supporting spatially referenced regression modeling in the Chesapeake Bay Watershed.

The U.S. Geological Survey has developed a methodology for statistically relating nutrient sources and land-surface characteristics to nutrient loads of streams. The methodology is referred to as SPAtially Referenced Regressions On Watershed attributes (SPARROW), and relates measured stream nutrient loads to nutrient sources using nonlinear statistical regression models. A spatially detailed digital hydrologic network of stream reaches, stream-reach characteristics such as mean streamflow, water velocity, reach length, and travel time, and their associated watersheds supports the regression models. This network serves as the primary framework for spatially referencing potential nutrient source information such as atmospheric deposition, septic systems, point-sources, land use, land cover, and agricultural sources and land-surface characteristics such as land use, land cover, average-annual precipitation and temperature, slope, and soil permeability. In the Chesapeake Bay watershed that covers parts of Delaware, Maryland, Pennsylvania, New York, Virginia, West Virginia, and Washington D.C., SPARROW was used to generate models estimating loads of total nitrogen and total phosphorus representing 1987 and 1992 land-surface conditions. The 1987 models used a hydrologic network derived from an enhanced version of the U.S. Environmental Protection Agency's digital River Reach File, and course resolution Digital Elevation Models (DEMs). A new hydrologic network was created to support the 1992 models by generating stream reaches representing surface-water pathways defined by flow direction and flow accumulation algorithms from higher resolution DEMs. On a reach-by-reach basis, stream reach characteristics essential to the modeling were transferred to the newly generated pathways or reaches from the enhanced River Reach File used to support the 1987 models. To complete the new network, watersheds for each reach were generated using the direction of surface-water flow derived from the DEMs. This network improves upon existing digital stream data by increasing the level of spatial detail and providing consistency between the reach locations and topography. The hydrologic network also aids in illustrating the spatial patterns of predicted nutrient loads and sources contributed locally to each stream, and the percentages of nutrient load that reach Chesapeake Bay.

Delaware↗

PubMed1997

Virtual shelves. II: A unified catalog for a heterogeneous collection.

We describe a unified catalog of traditional and digital resources in medical informatics, using standard cataloging principles (AACR2), schemes (LCC), and coding formats (USMARC). The unified catalog integrates the bibliographic records of physical items in the heterogeneous collection with the bibliographic records of network accessible digital items, using prescribed cataloging formats to new effect. The unified catalog is collections-based. We do not use the MARC 856 field to specify the network location of a digital item. The location of a digital item is determined by mapping its call number through a location guide to a network address. This mapping is strictly isomorphic to the way the shelf location of a physical item is determined within the bounds of a controlled collection.

Book Classification↗

PubMed2004

Estimating the safety performance of urban road transportation networks.

Transportation planning models are typically used to estimate future traffic patterns, peak period traffic, travel time, and various environmental or other related traffic flow characteristics. Unfortunately, traffic safety is seldom, if ever, explicitly considered proactively during the transportation planning process. This omission is attributed to various factors, including the lack of available tools needed to estimate the number of crashes during this process. To help fill this void, the research on which this paper is based aimed, as a primary objective, to develop a tool that would allow the estimation of crashes on digital or coded urban transportation networks during the planning process. The secondary objective of the research was to describe how the predictive models should be applied on these networks and explain the important issues and limitations surrounding their application. To accomplish these objectives, safety performance functions specifically created for this work were applied to two sample digital networks created with the help of EMME/2, a software package widely used in transportation planning. The results showed that it is possible to predict crashes on digital transportation networks, but confirmed the reality that the accuracy of the predictions is directly related to the precision of the traffic flow estimates. The crash predictions are also sensitive to how the digital network is coded, and it is shown how appropriate adjustments can be made.

Accidents, Traffic↗

PubMed1994

Integrating a digital dictation system with a network data base for creating and managing radiologic teaching files.

RATIONALE AND OBJECTIVES: A method for facilitating the creation and management of radiologic teaching files is described. METHODS: A digital dictation system was integrated with a personal computer data base. The data base is maintained with user-friendly, graphically oriented software. Radiologists can dictate any examination for the teaching file from any dictation station in the department with minimal interruption of their clinical activities. The data base resides on a file server, thus providing department-wide access for radiologists and students. RESULTS: Attending radiologists and residents have responded favorably to the system. Maintenance and retrieval of teaching files are facilitated by using a computer for otherwise tedious aspects of information management. Data are stored in a well-organized manner, thus increasing the value of the teaching file while reducing redundant data entry. CONCLUSION: Computer technology can facilitate the maintenance of radiologic teaching files. Radiology departments that have a convenient, department-wide method for entering cases--such as a digital dictation system and existing computer network--are ideal for the technique that we describe.

Humans↗

PubMed1966

Rhythmic activity in a simulated neuronal network.

1. A digital computer has been programmed to simulate a neuronal network consisting of eighty cells with the following characteristics:(a) All cells in the network had a set random probability of discharge when not affected by other cells. The probability of discharge was chosen as one system parameter (PD).(b) Subsequent to the firing of any neurone in the network, a certain number of other neurones underwent a change in their probability of discharge, consisting of an inhibitory period followed by a period of increased excitability. The changes of excitability mimic the changes of the membrane potential recorded for spontaneously rhythmically active cells in the animal thalamus.2. Starting the network, a typical transient response appeared, consisting of a burst-like activity. The initial activity was followed, first by random fluctuations of the number of active cells, later by periods of spontaneous rhythmic activity that had several characteristics in common with the type of spontaneous activity seen in the animal thalamus.3. The parameters which affected the rhythmic activity of the network most strongly were the degree of the post-inhibitory increase of the probability of discharge and the degree of distribution of the inhibition to neighbouring cells.4. The results are compatible with the inhibitory phasing theory advanced by Andersen & Sears (1964) to explain the occurrence of spontaneous rhythmic activity in the animal thalamus. However, before sufficient experimental knowledge is available, it is difficult to establish whether the rhythmic activity in the network is of the same type as that of the animal thalamus.5. A closer study of the parameters governing the behaviour of the simulated network has given indications of some parameters to be more closely investigated in future animal experiments.

Journal Article↗

PubMed2003

Applying new thinking from the linked and emerging fields of digital identity and privacy to information governance in health informatics.

Recent work in the emerging field of network or digital identity suggests a new approach to the design of informatics systems, in which the individual becomes the guardian of their own personal data, and is assisted in controlling access to it by an infrastructure that is aware of roles, such as 'doctor', and relationships, such as 'doctor-patient'.For these purposes, an 'identity' is defined as the history of a relationship between two entities, and thus encompasses not only name and address but also data that would usually be regarded as part of an electronic patient or health record. This paper presents a description of how such a true person-centric architecture might work, and shows how it can be seen as an evolution of current plans in the NHS for a national patient data spine. One application, the electronic transmission of prescriptions, is described in detail. Other applications, both within and without the healthcare field, are described in outline. The implementation of such a person-centric system requires a modest degree of technical innovation, but significant change in organisational and business models. It is suggested that there is a need for one or more not-for-profit trusts, each with a remit to act as host for an individual's digital identity, and as the individual's true agent. Service providers - such as healthcare organisations - will pay the trust for provision of authentication, and for the storage and transmission of a patient's data; the trust in turn will pay implementation partners, such as smart card issuers and providers of communication channels, acting on behalf of the individual.

Access to Information↗

PubMed1997

[Experimental study and clinical use of the dorsal digital flag flap].

To investigate the survival mechanism of the dorsal digital flag flap, an animal experiment was undertaken in a monkey. Eight dorsal digital flag flaps were created and examined by clinical observations, laser Doppler and biopsy. Of them six flaps were proximal-based and two were distal-based. The results showed: 1. The flag flaps survived without purplish discoloration or blister formation when the length-width ratio reached 10:1; 2. The perfusion unit measured by laser Doppler flowmetry decreased on the second postoperative day and began to increase from the third day, and returned to or surpass the preoperative level on the fifth day; 3. Biopsies confirmed that there was no specific artery in the pedicle of the flag flap but a rich dorsal digital venous network. The results indicated that the flag flap is a venous flap. Its arterial perfusion passed through the perivenous vascular network of the pedicle while the venous drainage is through the dorsal digital veins. Based on this study, 20 venous dorsal digital flag flaps have been used for reconstruction of digital defects associated with exposure of bone or tendon in 12 patients. Satisfactory results were obtained in all cases.

Adolescent↗

PubMed2006

The sensitivity and specificity of nonmydriatic digital stereoscopic retinal imaging in detecting diabetic retinopathy.

OBJECTIVE: The objective of this study was to determine the sensitivity and specificity of Joslin Vision Network nonmydriatic digital stereoscopic retinal imaging (NMDSRI) as a screening tool in detecting diabetic retinopathy. RESEARCH DESIGN AND METHODS: We reviewed the records of 244 patients with diabetes who had a dilated funduscopic examination (DFE) and NMDSRI done within 1 year of each other at four locations in the metropolitan Washington, DC, area. The images were transmitted through a local area network to a central reading location where they were graded by a single retinal specialist. RESULTS: Images of 482 eyes from 243 patients were included in the study. Four images did not transmit, and 35% of the images were not gradable. Of the remaining 311 eyes, there was 86% agreement in the grading between NMDSRI and DFE: 227 eyes with no diabetic retinopathy and 40 eyes with diabetic retinopathy. In 46 eyes (15%) there was a disagreement between gradings made by the two techniques. NMDSRI detected diabetic retinopathy in 35 eyes reported as normal by DFE, and in the remaining 11 eyes, the DFE grade was one grade higher than the NMDSRI grade. Adjudicated nonconcordant examinations were within one grade. In the 76 eyes with diabetic retinopathy, retinal thickness could not be assessed in 17 (21%) eyes. When the NMDSRI result was gradable, the overall sensitivity of NMDSRI was 98% and the specificity was 100% for retinopathy within one grade of the DFE. In the limited number of eyes that had diabetic retinopathy with macular edema (six), agreement with the clinical examination was 100%. CONCLUSIONS: NMDSRI is a sensitive and specific method for the screening and diagnosis of diabetic retinopathy, which may help improve compliance with the standards of eye care for patients with diabetes.

Aged↗

PubMedDate not supplied

Artificial neural networks and three-dimensional digital morphology: a pilot study.

In this pilot study, we used an unsupervised learning algorithm for self-organization and pattern matching to create feature maps that can be applied to morphological problems. We designed a network to analyze 83 first and/or second upper and lower molar sets representing 13 anthropoid primate species, based on three-dimensional measures obtained from laser-digitized, virtual specimens. As shown in a comparison with a principal-component analysis of the virtual specimens, the artificial neural network approach provided more biologically meaningful information than the conventional multivariate analysis approach. The methodology discovered partitions and hierarchical clusters consistent with anthropoid systematics, from the species (or subspecies) level to the highest categories, by sorting and allocating upper and lower molar teeth. As one might expect, measures of upper molars were richer in phenetic information than those of lower molars, even among the anatomically diverse platyrrhines. We also show that reducing taxonomic noise (i.e. biological variation) by limiting the analysis to a monophyletic subset improves discrimination.

Algorithms↗

PubMedDate not supplied

A limited PACS dedicated to a research environment. Nine years' experience in Santiago de Compostela.

A digital image network has been installed at the Department of Radiology of the University of Santiago de Compostela, Spain, to create a "limited' Picture Archiving and Communication System (PACS). This experience is being dedicated to address problems associated with digital techniques in a research environment. The backbone of the system is a multiprotocol ethernet network. Attached to the network are a number of advanced devices such as DEC VAX and UNIX workstations. Currently, a high resolution film digitizer and a laser printer are under evaluation for radiologic image research. During a period of nine years, 1987 to 1995, experimental and clinical trials have been conducted on different film based digital radiography apparatus primarily dedicated to chest and breast imaging. Several research projects have been completed. In this paper we describe the results of these investigations and discuss the advantages and disadvantages of this digital technique. The results of the different completed studies will be presented separately. A description of the physical characteristics of the limited PACS system dedicated to a research environment will serve as background.

Computer Communication Networks↗

PubMed2001

The construction of a public key infrastructure for healthcare information networks in Japan.

The digital signature is a key technology in the forthcoming Internet society for electronic healthcare as well as for electronic commerce. Efficient exchanges of authorized information with a digital signature in healthcare information networks require a construction of a public key infrastructure (PKI). In order to introduce a PKI to healthcare information networks in Japan, we proposed a development of a user authentication system based on a PKI for user management, user authentication and privilege management of healthcare information systems. In this paper, we describe the design of the user authentication system and its implementation. The user authentication system provides a certification authority service and a privilege management service while it is comprised of a user authentication client and user authentication serves. It is designed on a basis of an X.509 PKI and is implemented with using OpenSSL and OpenLDAP. It was incorporated into the financial information management system for the national university hospitals and has been successfully working for about one year. The hospitals plan to use it as a user authentication method for their whole healthcare information systems. One implementation of the system is free to the national university hospitals with permission of the Japanese Ministry of Education, Culture, Sports, Science and Technology. Another implementation is open to the other healthcare institutes by support of the Medical Information System Development Center (MEDIS-DC). We are moving forward to a nation-wide construction of a PKI for healthcare information networks based on it.

Computer Communication Networks↗

PubMed1995

Detection of lung nodules in digital chest radiographs using artificial neural networks: a pilot study.

Radiologists can fail to detect up to 30% of pulmonary nodules in chest radiographs. A back-propagation neural network was used to detect lung nodules in digital chest radiographs to assist radiologists in the diagnosis of lung cancer. Regions of interest (ROIs) that contained nodules and normal tissues in the lung were selected from digitized chest radiographs by a previously developed computer-aided diagnosis (CAD) scheme. Different preprocessing techniques were used to produce input data to the neural network. The performance of the neural network was evaluated by receiver operating characteristic (ROC) analysis. We found that subsampling of original 64- x 64-pixel ROIs to smaller 8- x 8-pixel ROIs provides the optimal preprocessing for the neural network to distinguish ROIs containing nodules from false-positive ROIs containing normal regions. The neural network was able to detect obvious nodules very well with an Az value (area under ROC curve) of 0.93, but was unable to detect subtle nodules. However, with a training method that uses different orientations of the original ROIs, we were able to improve the performance of the neural network to detect subtle nodules. Artificial neural networks have the potential to serve as a useful classifier to help to eliminate the false-positive detections of the CAD scheme.

False Positive Reactions↗

PubMed1994

Hospital-wide PACS with a digital image intensifier TV system.

Tokyo Hitachi Hospital, Hitachi Ltd., has used a hospital-wide PACS for over 1 year. The system runs a 100 Mb/s optical fiber network over the whole hospital including wards and outpatient clinic rooms, with 11 image workstations. The network links digital imaging modalities such as X-CT, MRI, computed radiography (CR) and digital radiography (DR) with a 2048 x 2048 (2k x 2k) matrix image intensifier television (I.I.-TV) system. These modalities generate about 200 images/day. The system has managed over 300,000 images of about 8000 patients so far. Although being still under improvement, the system has really been used for routine work. The hospital-wide PACS of a small hospital has been proved to be very useful for both image diagnosis and image management.

Computer Terminals↗

PubMed1992

The blood supply of digital nerves: a microanatomical study of superficial and deep palmar venous networks.

In this work on vascularization of digital nerves, we have studied the anatomy of the deep network of venae comitantes of digital arteries, and the system of superficial palmar venules. 22 specimens of nerve and artery were dissected as one unit and were infused with Microfil prior to study under the microscope. The deep venous network, a satellite of the digital artery, can be classified into four types. A true network of deep venae comitantes exists in three of these four types, drained by deep veins arising from the transverse anastomotic arches between the palmar digital pedicles. Vascularization of the digital nerve is supplied by numerous anastomotic vessels connecting epineurial vessels, digital artery and the periarterial network (venae comitantes and vasa vasorum). This anatomical configuration lends itself to vascularized nerve grafting; for example, it is possible to use a nerve/artery graft taken as a unit from an amputated finger unsuitable for replantation. Two types of valves in this superficial venous network have been identified and their function is discussed.

Adult↗