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PubMedDate not supplied

Automated system for measurement of mechanics of breathing.

We describe a complete automated system for measurement of total respiratory resistance and compliance, and of pulmonary resistance and compliance in humans and anesthetized animals. The device for testing the chest-lung system consists of a sinusoidal pump with a stroke adjustable from 20 ml to 600 ml over a cycling frequency of 0.3 to 30 Hz. Pressure and flow or volume are inputted into an analog network for wave shaping, then to an arithmetic unit composed of sample-and-hold amplifiers, peak, minimum and zero detecting circuits, an analog division circuit, and a digital logic processor. The computer takes the peak-to-peak amplitude of one of two sinusoidal inputs at 0.3 to 10 Hz and the corresponding amplitude of the other input in the presence of a.c. noise and d.c. shifts, divides one into the other, and displays an answer on a digital voltmeter. In addition, the analog output is displayed on the cathode-ray tube of a storage oscilloscope. Plots of total resistance and pulmonary resistance are recorded as a function of lung volume in both humans inspiring voluntarily as well as anesthetized dogs inflated by positive pressure from the test apparatus. Total and pulmonary dynamic compliance, as a function of breathing frequency, can only be measured by the computer if a symmetrical waveform is presented to it. This cannot be achieved in spontaneously breathing subjects but is accomplished in apneic animals by producing sinusoidal oscillations from the test apparatus. Our on-line method for measurement of total respiratory resistance is now used in the Clinical Pulmonary Laboratory for experimental work, and we are in the process of obtaining values in normal subjects.

Adult↗

PubMed1998

Platform independent implementation of DICOM-based miniPACS.

Platform independence is an important issue for a software designed to run across a hospital environment which is practically always heterogeneous one. This paper presents a simple miniPACS solution designed over an existing Intranet (Internet limited to a local area network). Platform independence is achieved with Java programming language which allows resulting code to be executed on virtually all machines. System consists of a server application providing DICOM (Digital Imaging and Communications in Medicine) services and clients that can use these services over a TCP/IP connection. The server application is capable of an image storage and supports a query mechanism to allow access to stored data, thus the clients may perform two major functions: providing image data for archiving or image retrieval for viewing. Presented client application provides both these functions. It retrieves stored images for further processing and returns calculated results to the archive. The parts of the system are connected through a DICOM interface. Consequently the system architecture is open and any devices like scanners or viewing stations supporting specific DICOM services may be attached.

Humans↗

PubMed2004

A novel mobile transtelephonic system with synthesized 12-lead ECG.

The problem of synthesizing the standard 12-lead electrocardiogram (ECG) from the signals recorded using three special ECG leads is studied in detail. The implementation of that concept into the design of a new mobile ECG transtelephonic system is presented. The system has two separate units: a stationary diagnostic-calibration center and a mobile ECG device with integrated electrodes. The patient records by himself three special leads with the mobile ECG recorder and sends data via cellular phone to the personal computer in the diagnostic center where standard 12-lead ECG is numerically reconstructed on the base of the patient transformation matrix previously calculated into the calibration process. The experimental study shows high accuracy of the reconstructed ECG.

Activities of Daily Living↗

PubMed1993

High-resolution computer display of portable, digital, chest radiographs of adults: suitability for primary interpretation.

OBJECTIVE: The suitability of using a high-resolution computer-display system for primary interpretation of adult chest radiographs obtained with portable apparatus and storage phosphor technology was evaluated with receiver operating characteristic analysis and subjective methods. MATERIALS AND METHODS: Sixty portable digital chest radiographs showing abnormalities that approached the resolution limits of our computed radiography system were selected. The original digital data making up the 2140 x 1760 x 10 bit images were transferred to a cathode ray tube (CRT) display system composed of two Megascan monitors. Postprocessing rendered two images, one for each monitor, to emulate the two-on-one hard-copy format produced by the computed radiography system. Each image set was interpreted independently by three radiologists experienced with hard-copy format. Limited level and window adjustments were allowed during CRT interpretation. For both CRT and hard-copy display, images were graded on the basis of the interpreter's confidence in the presence of pneumothorax and parenchymal abnormalities. Three types of foreign devices were subjectively analyzed: endotracheal tubes, nasogastric tubes, and temporary epicardial pacer wires. RESULTS: No significant differences were found in detecting pneumothorax or focal infiltrates. One radiologist found the hard copy better for detecting diffuse infiltrates (p = .02); two radiologists favored CRT for visualizing nasogastric tubes (p < .005, p < .02); and one radiologist favored CRT for visualizing temporary epicardial pacer wires (p = .05). CONCLUSION: We conclude that an optimized high-resolution CRT system is quite promising for primary interpretation of digital portable chest radiographs, but further investigation and greater statistical power are necessary to confirm our results.

Adult↗

PubMed2005

Direct comparison of a tablet computer and a personal digital assistant for point-of-care documentation in eye care.

New mobile computing devices including personal digital assistants (PDAs) and tablet computers have emerged to facilitate data collection at the point of care. Unfortunately, little research has been reported regarding which device is optimal for a given care setting. In this study we created and compared functionally identical applications on a Palm operating system-based PDA and a Windows-based tablet computer for point-of-care documentation of clinical observations by eye care professionals when caring for patients with diabetes. Eye-care professionals compared the devices through focus group sessions and through validated usability surveys. We found that the application on the tablet computer was preferred over the PDA for documenting the complex data related to eye care. Our findings suggest that the selection of a mobile computing platform depends on the amount and complexity of the data to be entered; the tablet computer functions better for high volume, complex data entry, and the PDA, for low volume, simple data entry.

Attitude of Health Personnel↗

PubMed1992

Overruled: objections to optical disk archiving.

In summary, while the Federal Rules of Evidence neglect to specifically address the admission of optical disk evidence, the Rules do recognize the reliability and admissibility of records maintained with modern computer storage techniques. In certain cases, information stored on optical disk will constitute original information; in others, the information will constitute an admissible duplicate. Regardless of the classification, the optical disk evidence should be admissible if the party offering the evidence can establish that the optical disk storage and retrieval process accurately reproduces the original document. The admission of medical records stored on optical disk will be challenged. The technology involved in optical disk storage, however, makes optical disk information more reliable than magnetic disk information. As a result, optical disk evidence currently should survive challenges more readily than magnetic disk evidence.

Documentation↗

PubMedDate not supplied

Color nonuniformity in projection-based displays: analysis and solutions.

Large-area displays made up of several projectors show significant variation in color. In this paper, we identify different projector parameters that cause the color variation and study their effects on the luminance and chrominance characteristics of the display. This work leads to the realization that luminance varies significantly within and across projectors, while chrominance variation is relatively small, especially across projectors of same model. To address this situation, we present a method to achieve luminance matching across all pixels of a multiprojector display that results in photometrically uniform displays. We use a camera as a measurement device for this purpose. Our method comprises a one-time calibration step that generates a per channel per projector luminance attenuation map (LAM), which is then used to correct any image projected on the display at interactive rates on commodity graphics hardware. To the best of our knowledge, this is the first effort to match luminance across all the pixels of a multiprojector display.

Algorithms↗

PubMedDate not supplied

HDR VolVis: high dynamic range volume visualization.

In this paper, we present an interactive high dynamic range volume visualization framework (HDR VolVis) for visualizing volumetric data with both high spatial and intensity resolutions. Volumes with high dynamic range values require high precision computing during the rendering process to preserve data precision. Furthermore, it is desirable to render high resolution volumes with low opacity values to reveal detailed internal structures, which also requires high precision compositing. High precision rendering will result in a high precision intermediate image (also known as high dynamic range image). Simply rounding up pixel values to regular display scales will result in loss of computed details. Our method performs high precision compositing followed by dynamic tone mapping to preserve details on regular display devices. Rendering high precision volume data requires corresponding resolution in the transfer function. To assist the users in designing a high resolution transfer function on a limited resolution display device, we propose a novel transfer function specification interface with nonlinear magnification of the density range and logarithmic scaling of the color/ opacity range. By leveraging modern commodity graphics hardware, multiresolution rendering techniques and out-of-core acceleration, our system can effectively produce an interactive visualization of large volume data, such as 2,048(3).

Algorithms↗

PubMed2003

Implementation of a WAP-based telemedicine system for patient monitoring.

Many parties have already demonstrated telemedicine applications that use cellular phones and the Internet. A current trend in telecommunication is the convergence of wireless communication and computer network technologies, and the emergence of wireless application protocol (WAP) devices is an example. Since WAP will also be a common feature found in future mobile communication devices, it is worthwhile to investigate its use in telemedicine. This paper describes the implementation and experiences with a WAP-based telemedicine system for patient-monitoring that has been developed in our laboratory. It utilizes WAP devices as mobile access terminals for general inquiry and patient-monitoring services. Authorized users can browse the patients' general data, monitored blood pressure (BP), and electrocardiogram (ECG) on WAP devices in store-and-forward mode. The applications, written in wireless markup language (WML), WMLScript, and Perl, resided in a content server. A MySQL relational database system was set up to store the BP readings, ECG data, patient records, clinic and hospital information, and doctors' appointments with patients. A wireless ECG subsystem was built for recording ambulatory ECG in an indoor environment and for storing ECG data into the database. For testing, a WAP phone compliant with WAP 1.1 was used at GSM 1800 MHz by circuit-switched data (CSD) to connect to the content server through a WAP gateway, which was provided by a mobile phone service provider in Hong Kong. Data were successfully retrieved from the database and displayed on the WAP phone. The system shows how WAP can be feasible in remote patient-monitoring and patient data retrieval.

Blood Pressure↗

PubMed2006

Relief texture from specularities.

In vision and graphics, advanced object models require not only 3D shape, but also surface detail. While several scanning devices exist to capture the global shape of an object, few methods concentrate on capturing the fine-scale detail. Fine-scale surface geometry (relief texture), such as surface markings, roughness, and imprints, is essential in highly realistic rendering and accurate prediction. We present a novel approach for measuring the relief texture of specular or partially specular surfaces using a specialized imaging device with a concave parabolic mirror to view multiple angles in a single image. Laser scanning typically fails for specular surfaces because of light scattering, but our method is explicitly designed for specular surfaces. Also, the spatial resolution of the measured geometry is significantly higher than standard methods, so very small surface details are captured. Furthermore, spatially varying reflectance is measured simultaneously, i.e., both texture color and texture shape are retrieved.

Algorithms↗

PubMed1998

Data base and management system for clinical positron emission tomography (PET) studies.

A data base and management system connected to an image analysis system has been developed and utilized for clinical positron emission tomography (PET). This data base system, 1) is based on "GBASE", a general purpose data base, which runs on a UNIX work station, 2) works on a network file system and is connected to PET cameras and other data acquisition devices as well as to an image analysis system "Dr.View", 3) centrally manages the data stored in a data storage unit, 4) is easily modifiable and expandable, and 5) has a human friendly interface which requires minimum operation for registration, retrieval and management. We have been using this system to handle clinical PET data for seven years and have optimized the data base schema. As a result, this system has become a truly practical tool for the daily operation and is well-received by technologists, nuclear physicians and attending physicians.

Brain↗

PubMed2006

Video halftoning.

This paper studies video halftoning that renders a digital video sequence onto display devices, which have limited intensity resolutions and color palettes, by trading the spatiotemporal resolution for enhanced intensity/color resolution. This trade is needed when a continuous tone video is not necessary or not practical for video display, transmission, and storage. In particular, the quantization error of a pixel is diffused to its spatiotemporal neighbors by separable one-dimensional temporal and two-dimensional spatial error diffusions. Motion-adaptive gain control is employed to enhance the temporal consistency of the visual patterns by minimizing the flickering artifacts. Experimental results of halftone and colortone videos are demonstrated and evaluated with various halftoning techniques.

Algorithms↗

PubMed1989

[Fluorescence diagnosis of porphyrin-marked urothelial tumors. Status of experimental development].

On the basis of selective storage of fluorescing hematoporphyrin derivative (HpD) in tumors, a method has been developed that enables the endoscopic detection of early-stage cancer by monitoring fluorescent images. The contrast-reducing portion of the superposed tissue autofluorescence is suppressed by the use of two-wavelength excitation and subsequent image processing in realtime. The amount of photosensitizing HpD necessary for diagnostic purposes is considerably reduced by means of sensitive detection devices. A clear distinction between benign and malignant bladder tissue seems possible according to the results of animal studies.

Animals↗

PubMed1995

Quality control of storage phosphor digital radiography systems.

Quality control (QC) of storage phosphor devices is important in assuring that the image information entered into an Image management and communication (IMAC) system is sufficient for diagnosis. QC of storage phosphor digital radiography systems is complex because of the self-corrective nature of the image-processing software used in these machines. Currently, one must produce hard copy to perform adequate QC. Inspection of images with reject analysis and inspection of cassettes and imaging plates has helped us in our QC program. For those QC tests using control limits, the appropriate settings for these limits are unknown. Starting approximations are given. Recommended tests are described.

Equipment Failure↗

PubMedDate not supplied

Dynamic range reduction inspired by photoreceptor physiology.

A common task in computer graphics is the mapping of digital high dynamic range images to low dynamic range display devices such as monitors and printers. This task is similar to the adaptation processes which occur in the human visual system. Physiological evidence suggests that adaptation already occurs in the photoreceptors, leading to a straightforward model that can be easily adapted for tone reproduction. The result is a fast and practical algorithm for general use with intuitive user parameters that control intensity, contrast, and level of chromatic adaptation, respectively.

Algorithms↗

PubMedDate not supplied

Informatics in radiology (infoRAD): A complete continuous-availability PACS archive server.

The operational reliability of the picture archiving and communication system (PACS) server in a filmless hospital environment is always a major concern because server failure could cripple the entire PACS operation. A simple, low-cost, continuous-availability (CA) PACS archive server was designed and developed. The server makes use of a triple modular redundancy (TMR) system with a simple majority voting logic that automatically identifies a faulty module and removes it from service. The remaining two modules continue normal operation with no adverse effects on data flow or system performance. In addition, the server is integrated with two external mass storage devices for short- and long-term storage. Evaluation and testing of the server were conducted with laboratory experiments in which hardware failures were simulated to observe recovery time and the resumption of normal data flow. The server provides maximum uptime (99.999%) for end users while ensuring the transactional integrity of all clinical PACS data. Hardware failure has only minimal impact on performance, with no interruption of clinical data flow or loss of data. As hospital PACS become more widespread, the need for CA PACS solutions will increase. A TMR CA PACS archive server can reliably help achieve CA in this setting.

Computer Communication Networks↗

PubMed2000

Digital photography in the dental practice--an overview (II).

The advantage of digital cameras is the instant, digitalized availability of photos. The image quality has reached that of conventionally taken photographs, and for most applications, the digital origin of the photo is no longer discernable. Thus, digital photos are suited for immediate data transmission, for instance to the lab or a colleague. Similarly, they can also be instantly integrated into the practice's software and stored there. If one expects the same quality of digital photo documentation as from conventional photo documentation, then there is no alternative to the still-expensive professional digital reflex cameras, which are in the same price range as intraoral videosystems. These systems can be considered technically mature and suitable for routine practice applications. However, the advantages of digital photos can only be had at greater technical (regarding cameras and peripheral devices) expense. Amateur-class digital viewfinder cameras and reflex cameras without zoom lenses have only limited applications in terms of documentation, where they may supplement conventional photography. Before acquiring a digital camera, it makes good sense to draw up a cost-benefit list and consider alternatives. As dental practices become more and more computerized, digital photo documentation will also be a standard procedure of the future. In any case, it is worthwhile to start looking closely at these media now.

Equipment Design↗

PubMed1999

Use of portable CT in the R Adams Cowley Shock Trauma Center. Experiences in the admitting area, ICU, and operating room.

The author's experience with portable CT has been positive. Nurses and clinical physicians have been pleased with this new imaging capability also, and have written testimonial letters endorsing its value. Recently, the STC extended availability of the mobile CT to the University of Maryland Hospital, an adjoining 600-bed center with numerous medical and surgical patients in ICU. They are particularly interested in assessing use of portable CT in the neonatal ICU, where patient transport outside the unit is particularly difficult and dangerous. Technical improvements for portable CT are in development. Soon, helical volume scanning will be available, allowing faster image acquisition and better two- and three-dimensional image reformations (Fig. 12). A new, more powerful x-ray tube is in development that will permit more slices to be acquired without tube cooling interruptions. Gantry translate capability coupled with a radiolucent backboard extender has the potential to permit scanning of the head, neck, spine, face, and upper torso without the patient being moved from the ICU bed. For applications in head, face, and neck surgery, a radiolucent cranial fixation device also has been developed. Other potential improvements include extended battery power for more scanning between charges, a larger tube heat unit storage for extended scanning situations, decreased system weight for easier transport, and more detector efficiency for improved image quality while maintaining significant dose reduction over conventional scanning. The capability of portable CT scanning for emergency, intensive care, and intraoperative studies exists now. The commercially marketed cost for this system is between $400,000 and $500,000. Further studies are anticipated to clarify the economic and clinical benefits of this technology.

Admitting Department, Hospital↗