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PubMed2004

An improved automated ultrasonic NDE system by wavelet and neuron networks.

Despite of the widespread and increasing use of digitized signals, the ultrasonic testing community has not realized yet the full potential of the electronic processing. The performance of an ultrasonic flaw detection method is evaluated by the success of distinguishing the flaw echoes from those scattered by microstructures. So, de-noising of ultrasonic signals is extremely important as to correctly identify smaller defects, because the probability of detection usually decreases as the defect size decreases, while the probability of false call does increase. In this paper, the wavelet transform has been successfully experimented to suppress noise and to enhance flaw location from ultrasonic signal, with a good defect localization. The obtained result is then directed to an automatic Artificial Neuronal Networks classification and learning algorithm of defects from A-scan data. Since there is some uncertainty connected with the testing technique, the system needs a numerical modelling. So, knowing the technical characteristics of the transducer, we can preview which are the defects that experimental inspection should find. Indeed, the system performs simulation of the ultrasonic wave propagation in the material, and gives a very helpful tool to get information and physical phenomena understanding, which can help to a suitable prediction of the service life of the component.

Materials Testing↗

PubMed2003

Image analysis of light distribution in a photobioreactor.

Light intensity is a crucial factor that determines the growth of photosynthetic cells. This study analyzed the light distribution in a photobioreactor by processing images, captured with a digital camera, of a rectangular photobioreactor containing Synechococcus sp. PCC6801 as a model microorganism. The gray-scale images obtained clearly demonstrate the variation of the light-distribution profiles upon changing cell concentrations and external light intensity. Image-processing techniques were also used to predict the cell density in the photobioreactor. By analyzing the digitized image data with a neural network model, we were able to predict the cell concentrations in the photobioreactor with a <5% error.

Algorithms↗

PubMed1994

Classification of wheat varieties by isoelectric focusing patterns of gliadins and neural network.

Classification of wheat varieties, using isoelectric focusing patterns of the gliadins, image processing and neural networks, is described. The method was compared to a statistical classification method, discriminant analysis. The isoelectric point and the area of each band were calculated by image processing. Different methods of presenting the electrophoretic patterns to the neural network were studied. The most effective method was transformation of the electrophoretic pattern to a small (11 x 47 pixels) representation of the original digitized image, which was presented to the neural network as a vector. The neural network was trained with a number of patterns and tested with new patterns from different electrophoretic runs of the same wheat varieties. In this study we used ten different wheat varieties and the neural network was able to classify 95.5% of the patterns correctly. The statistical classification method classified the same data set 91.8% correctly. We conclude that both the neural network and discriminant analysis were able to classify the patterns correctly with a high degree of certainty. The patterns that were misclassified were indistinguishable by visual inspection.

Discriminant Analysis↗

PubMed1980

Neocognitron: a self organizing neural network model for a mechanism of pattern recognition unaffected by shift in position.

A neural network model for a mechanism of visual pattern recognition is proposed in this paper. The network is self-organized by "learning without a teacher", and acquires an ability to recognize stimulus patterns based on the geometrical similarity (Gestalt) of their shapes without affected by their positions. This network is given a nickname "neocognitron". After completion of self-organization, the network has a structure similar to the hierarchy model of the visual nervous system proposed by Hubel and Wiesel. The network consists of an input layer (photoreceptor array) followed by a cascade connection of a number of modular structures, each of which is composed of two layers of cells connected in a cascade. The first layer of each module consists of "S-cells", which show characteristics similar to simple cells or lower order hypercomplex cells, and the second layer consists of "C-cells" similar to complex cells or higher order hypercomplex cells. The afferent synapses to each S-cell have plasticity and are modifiable. The network has an ability of unsupervised learning: We do not need any "teacher" during the process of self-organization, and it is only needed to present a set of stimulus patterns repeatedly to the input layer of the network. The network has been simulated on a digital computer. After repetitive presentation of a set of stimulus patterns, each stimulus pattern has become to elicit an output only from one of the C-cells of the last layer, and conversely, this C-cell has become selectively responsive only to that stimulus pattern. That is, none of the C-cells of the last layer responds to more than one stimulus pattern. The response of the C-cells of the last layer is not affected by the pattern's position at all. Neither is it affected by a small change in shape nor in size of the stimulus pattern.

Cognition↗

PubMed2005

Methodology for hypoglycaemia detection based on the processing, analysis and classification of the electroencephalogram.

Hypoglycaemia (blood glucose level below 3.8 mmol l(-1)) is the most common complication in the treatment of diabetes with insulin and can cause a number of problems. Previous works have shown that hypoglycaemia causes changes in the electroencephalogram (EEG) signal. In this investigation, portable apparatus was developed to record the EEG, and a methodology was implemented, using digital signal processing and artificial neural networks (ANNs), to detect hypoglycaemia. Sixteen EEG recordings were made on eight subjects with diabetes (five male, three female), aged 35 +/- 13.5 years (mean +/- SD), during the day, over periods of 5.7 +/- 2 min. Ten of these recordings (in seven subjects) included periods of normoglycaemia and spontaneous hypoglycaemia. The result of the off-line ANN classification for each of these ten recordings was an overall accuracy rate of 71.3%, sensitivity of 71.1% and specificity of 71.5%. In the classification using four recordings from a single subject, the accuracy was 80.6%, with a sensitivity of 77.8% and a specificity of 83.9%. In the classification using recordings from five different subjects to train the ANN, the obtained accuracy rate was 49.2%, with a sensitivity of 76% and a specificity of 32.5%. The result of the classification in real time, for one subject, was an accuracy rate of 85.2%, with a sensitivity of 60% and a specificity of 100%. In conclusion, the methodology proposed and implemented justifies further studies with the objective of constructing a hypoglycaemia detector system based on the processing and classification of the EEG.

Adult↗

PubMed1991

A system for automated recording and analysis of feeding behavior.

We have designed and implemented a system that utilizes a network of top-loading balances digitally interfaced to a Macintosh computer. The system simultaneously collects two forms of data which allow the evaluation of the animal's biting and/or licking behavior in addition to cumulative food intake and meal patterns. The system is capable of resuming data acquisition following a power failure without user intervention. Plexiglas cages utilized with the system features adjustable tunnel feeders and are appropriate for use with small rodents. Given appropriate caging, the system may be utilized to evaluate the feeding behavior of other species.

Animals↗

PubMedDate not supplied

Independent double reading system. Application of digital image management database.

The most important role in a radiologist's work is communicating his findings to the attending physician. This is difficult when the radiologic examinations are performed with portable X-ray units because the attending physician wishes to read the images as soon as possible. To resolve this problem, we have developed an independent double reading system. The hardware consists of a magnetic card reader, a display station, a personal computer and a mouse, all linked with the digital image database and a communication network between HIS and RIS. We also present the software of this system and evaluate the results of the implementation to establish the accuracy of the technique. It was concluded that this system could expand the contribution of the radiologist to portable radiographic examinations and to improve the quality of the RIS database.

Computer Systems↗

PubMedDate not supplied

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↗

PubMed1991

Retinal capillary blood flow measurement with a scanning laser ophthalmoscope. Preliminary results.

The scanning laser technique in combination with digital image analysis allows direct objective measurement of flow velocities in perimacular capillaries. In addition, the complete macular network of capillaries can be observed. By means of digital frame-to-frame picture analysis of digital recordings, blood flow velocities and morphologic data have been measured. The mean flow velocity in perimacular capillaries observed with the scanning laser ophthalmoscope in healthy subjects (n = 21) amounted to 3.28 +/- 0.45 mm/second. In patients (n = 13) with diabetes mellitus (no or background retinopathy), the mean flow velocity was significantly reduced (2.89 +/- 0.57 mm/seconds) compared with healthy subjects. Morphologic data of the perifoveal capillary bed showed a significant reduction of capillaries in patients with diabetes mellitus when compared with healthy subjects.

Adult↗

PubMed1992

PACS mini refresher course. Wide area network strategies for teleradiology systems.

Teleradiology systems require the use of wide area networks (WANs). Design and implementation of a WAN depend on the number of images to be transmitted, desired digital image throughput (based on signaling rate), and cost of the communications link. Image transmission load must be estimated before the communications link can be selected. Communications links used in WANs include T-1 carrier point-to-point service, digital service (DS)-1 dial-up service, DS-3 point-to-point service, DS-0 dial-up service, digital microwave, fiberoptic local loop carriers, and metropolitan area networks (MANs). Depending on the distance between sites, T-1 service may be less costly than DS-1 service; however, for distances more than 200 miles, DS-1 service can be less expensive and more flexible. Both of these services and DS-0 service have lower signaling rates than DS-3 service, which is the fastest and most expensive link. Microwave and fiberoptic links are less expensive but have distance limitations of 14 and 30 miles, respectively. MANs are still being developed but hold the promise of higher signaling rates at lower costs.

Computer Communication Networks↗

PubMed1998

It's a long way to multimedia: an account of 18 years of pursuing a new media project in physiology.

A teaching-oriented multimedia database authoring system, MILES ( Multimediales Informations- und Lehrsystem), has been in development since 1980 in our department. The hardware consists of a network of personal computers connected to digital and, until recently, audio/video storage devices. The system provides a database capable of handling all kinds of multimedia data and computer programs. User-friendly software provides input, editing, retrieval, and communication; the authoring system allows these components to be organized into structures of complex menus, combined with free database access. More than 12,000 components have been stored, including approximately 3,500 pictures. The paper reports on an extensive field test, in which the system has been applied as a common source for all kinds of materials used in teaching physiology to students of medicine. ResuIts show that the "new media" are powerful instruments for improving teaching and learning. However, they should not be expected to provide the sole basis for education. Their application still faces many problems regarding concepts, efficiency, and acceptance by students and staff.

Computer-Assisted Instruction↗

PubMed1997

Distributed clinical neurophysiology.

We have developed a consultation forum for clinical neurophysiology in Finland. The system connects local digital electroencephalography (EEG) recording and analysing networks using a high-speed asynchronous transfer mode (ATM) network. Clinicians can obtain a second opinion using interactive data and video consultations or using data-only consultations. In addition, the system can be used for off-line review of pre-recorded data. During a one-month evaluation, 66 EEG recordings were made altogether in Satakunta Central Hospital and consultations were required on 12 occasions. Nine of them were data-only consultations and three were data and video consultations. A data consultation lasted 15-20 min and a data and video consultation 35-45 min. Clinically, there were numerous benefits for the hospitals. The system established a link to a centre of excellence for second opinions or continuing education. It also helped with on-duty arrangements and enabled the construction of national data banks.

Electroencephalography↗

PubMed2003

Symptom assessment in home healthcare using digital pens.

We have developed a system allowing patients subject to palliative advanced home care to frequently submit symptom assessments from their homes. Using digital pen technology developed by Anoto AB, symptom assessments are transferred digitally over the GSM mobile phone network from the patient's home to the hospital clinic. The system is evaluated during spring 2003 at the hospital-based home care (HBHC) clinic of Linköping University Hospital.

Home Care Services, Hospital-Based↗

PubMed1993

VXIbus for biomedical applications: temperature measurement.

Medical technology must keep pace with the demands of health care to deliver cost-effective solutions. Automated test equipment can have an important role in medical technology just as it does in manufacturing test. The VXIbus architecture can field a wide range of instruments that could support many traditional biomedical instruments. For example, a patient monitoring system that possesses multiple channels of isolation, data acquisition, digital signal processing, storage, display, and networking could be integrated in a VXIbus system. Results could be displayed locally as well as networked as part of a larger hospital administration system. This article describes a project performed to demonstrate capabilities of VXIbus in biomedical applications. A simple temperature sensor is hosted on a B-size register based VXIbus card.

Computers↗

PubMed1988

[Study of the circle of Willis with digital angiography. Contribution to the detection of high-risk carotid clamping].

Radiological studies of Willis' circle morphology are mainly performed in search of intracerebral aneurysms, and for this purpose digital imaging has not superseded conventional radiology. In contrast, conventional imaging does not seem to have given satisfactory results in the functional study of this substitute vascular network, and it is in this field that digital angiography is of particular value. Between January, 1985 and June, 1986, we performed 300 digital angiographies of the supra-aortic vessels in patients with carotid artery stenosis. Each exploration included a stage of investigation for intracranial substitute vessels by compression of the carotid artery on the side of the lesion. Substitute vessels were found to be adequate in 93 p. 100 of the cases. The test showed that there was no alternative blood flow in 3.7 p. 100 of the cases, which made it imperative to use brain protection measures during clamping of the carotid artery. The substitute network was found to be insufficient in 1 p. 100 of the cases, and the method failed in 2.4 p. 100.

Carotid Arteries↗

PubMed1992

Modeling the circulation with three-terminal electrical networks containing special nonlinear capacitors.

Development, first of analog and later of digital computers, as well as algorithms for analysis of electrical circuits, stimulated the use of electrical circuits for modeling the circulation. The networks used as building blocks for electrical models can provide accurate representation of the hydrodynamic equations relating the inflow and outflow of individual segments of the circulation. These networks, however, can contain connections in which voltages and currents have no analogues in the circulation. Problems arise because (a) electrical current must flow in closed loops, whereas no such constraints exist for hydraulic models; and (b) electrical capacitors have a number of characteristics that are not analogous to those of hydraulic compliant chambers. Disregarding these differences can lead to erroneous results and misinterpretation of phenomena. To ensure against these errors, we introduce an imaginary electrical element, the nonlinear residual-charge capacitor (NRCC), with characteristics equivalent to those of a compliant chamber. If one uses appropriate circuit connections and incorporates the residual-charge capacitor, then all voltages and currents in the model are proper analogues of pressures and flows in the circulation. It is shown that the capacitive current represents the rate of change of volume of blood inside the vessel, as well as the rate of the corresponding displacement of volume of the surrounding tissue.

Blood Circulation↗

PubMedDate not supplied

Digital dental radiography needs assessment utilizing the Delphi process.

This article reports the results of a needs assessment using the Delphi process. The purpose of this study was to determine the architecture and equipment (radiographic and computer network) for establishing and supporting an enterprise's vast digital dental radiographic program. Two panels of subject matter experts identified the needs for a digital dental radiography system; one expert panel consisted of dentists while the other panel's members were information management/information technology (IM/IT) experts. Panelists rated digital dental radiography needs using descriptive statistics and a 7-point bipolar scale. Among dentists, the four most important needs were the capability to store images, image appearance, centralized image storage, and a dedicated back-up server; among IM/IT panelists, they were ensuring HIPAA compliance, use of a standard formatting procedure, excellent print quality, and use of encryption for data transmission. This study's findings are useful for any organization seeking to initiate or improve its own digital radiography program.

Computer Communication Networks↗

PubMed1998

Ultraviolet radiation of melanocytic nevi: a dermoscopic study.

BACKGROUND: UV radiation can lead to clinical, histological, and ultrastructural changes in melanocytic nevi. In this study, we investigated whether exposure to 2 minimal erythema doses of UV radiation induces changes in the dermoscopic image of acquired melanocytic nevi. OBSERVATIONS: Fifteen melanocytic nevi were exposed to 2 minimal erythema doses of UV radiation. Differences in dermoscopic parameters (asymmetry, border, erythema, and telangiectasias in the nevus; pigmentation; hypopigmented areas; presence, regularity, and sharpness of pigment network; and brown-black globules) in digital dermoscopic images taken before and 3, 7, 14, and 28 days after UV irradiation were scored. Three days after UV irradiation, the borders of nevi were more faded (P<.02), the nevi were darker brown (P<.02), the hypopigmented areas were smaller (P<.02), and the pigment network structures were more faded (P<.007) and less prominent (P<.02) than before UV irradiation. Seven days after UV irradiation, pigmented globules have also grown (P<.05). After 28 days, all parameters, except hypopigmented areas, were essentially the same as before UV irradiation. CONCLUSION: UV irradiation of melanocytic nevi with 2 minimal erythema doses induces transient changes in their dermoscopic appearance that are sometimes suggestive of malignant melanoma.

Adult↗