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At least 217 records · Page 12Linked to original sources
PubMed2003

A virtual reality system for the training of volunteers involved in health emergency situations.

In order to guarantee an effective and punctual medical intervention to injured people involved in health emergency situations, where usually both professional and non-professional health operators are involved, a fast and accurate treatment has to be carried out. In case of catastrophic or very critical situations, non-professional operators who did not receive proper training (volunteers are among them) could be affected by psychological inhibitions. Their performances could slow down in such way that would affect the quality of the treatment and increase both direct and indirect costs. Our virtual reality system that is currently in use at the health care emergency center of San Martino Hospital in Genoa, Italy, has been designed and developed to check health emergency operators' capabilities to adopt correct decision-making procedures, to make optimal use of new technological equipment and to overcome psychological barriers. Our system is composed of (1) a high-end simulation PC, whose main functions are execution of the main software module, rendering of 3D scenes in stereo mode, rendering of sound, and control of data transmission from/to VR devices; (2) a low-end control PC, which controls the VR simulation running on the simulation PC, manages medical emergency simulation scenarios, introduces unexpected events to the simulation and controls the simulation difficulty level; (3) a magnetic-based motion tracking device used for head and hand tracking; (4) a wireless pair of shutter glasses together with a cathode ray tube wall projector; and (5) a high-end surround sound system. The expected benefits have been verified through the design and implementation of controlled clinical trials.

Clinical Trials as Topic↗
PubMed1978

A computer-based reporting system for bone marrow evaluation.

A computerized system of reporting results of bone marrow examination has been implemented at The University of Texas System Cancer Center, M. D. Anderson Hospital and Tumor Institute, since 1975. All results are entered via the keyboard of cathode-ray tube (CRT) consoles and are instantly available to the attending physician in CRTs strategically located throughout the institution in patient-related areas. Differential counts are available within two to three hours after aspiration. Description of clot sections and smear, diagnosis, and differential diagnosis are completed within 24 hours. Permanent reports are also printed by the computer at regular intervals during the day. The physician can ask the computer for results on a given day or for a cumulative summary displayed in tabular or plot form. This system has proven efficient and rapid, not only for direct reporting of bone marrow examination results but also for storage and retrieval of patient information.

Bone Marrow Examination↗
PubMed1979

A computerized word-processing and data system for histology in a private medical laboratory.

This report describes the use of a word-processing micro-computer, the Lanier Text Editor, for preparation of surgical tissue reports. Gross and microscopic description formats are stored on floppy disks, which may easily be completed and edited on a cathode-ray tube (CRT) for rapid computerized printing. Also described is the use of a PDP 8/E mini-computer for entry, storage, and manipulation of historic, demographic and diagnostic data, printing of numeric and alphabetic listings, cross-indexing of cases by diagnosis, and the accumulation of data for direct patient or physician billing.

Computers↗
PubMed1983

Computer-assisted interpretive reporting with trend analysis of creatine kinase and lactate dehydrogenase isoenzyme determinations.

A program has been developed for a central laboratory computer that provides rapid, comprehensive interpretation of CK and LDH isoenzyme determinations. The laboratory computer can receive data on line from a densitometer or by manual result entry from a cathode ray tube. The program algorithm is based on extensive literature references and yields combinations of narrative comments selected from a file of statements. The algorithm is flexible and easily modified; it permits result correlation of simultaneously ordered CK and LDH studies as well as stand-alone interpretation of these tests requested separately. Trend analysis permits identification of changes from previous results and detection of asynchronous appearances of CK-MB and LD-1 as diagnostic of myocardial injury. The output can be formatted to suggest a strategy for further laboratory evaluation of a patient with suspected myocardial injury. Blind sample analysis of 1,500 sets of patient isoenzyme data, comparing human and computer results, has shown that the program is accurate, consistent, and reliable in a variety of clinical circumstances.

Coronary Artery Bypass↗
PubMed1988

Latency and accuracy of word recognition in dementia of the Alzheimer type.

The sensitivity of reaction time (RT) measurement in assessing cognitive decline in dementia of the Alzheimer type (DAT) was evaluated. Sixteen DAT patients and 16 normal elderly controls, matched for age and education, read 50 stimulus words presented individually on a cathode-ray tube. DAT patients exhibited a significantly greater cognitive impairment as shown by multivariate analysis of variance (p less than 0.0001). Canonical variate correlations revealed RT (0.961) to be more sensitive to decline in cognitive functioning in dementia than the measure of number of reading errors (0.559). Results confirm that RT is a highly sensitive measure of central nervous system integrity, which allows for a more refined investigation of a patient's cognitive deficit than is obtainable with traditional test measures. These findings suggest that chronometric measures should be incorporated in clinical and research studies attempting to document the existence and severity of cognitive impairment in neurodegenerative disease.

Aged↗
PubMed1989

Smooth pursuit eye movements in dementia of the Alzheimer type.

Smooth pursuit eye movements (SPEM) to a sinusoidally modulated target moving horizontally across a cathode ray tube screen were examined for 17 patients with dementia of the Alzheimer type (DAT) and for 14 age-matched control subjects. There were 3 target-motion conditions at frequencies representing varying ranges of target velocity. DAT patients differed from controls on all measures of smooth pursuit quality: their gain was reduced at high target velocities and lower target accelerations, they made more frequent directionally appropriate saccades and had more saccadic intrusions, they led the target with their eyes (phase lead) in all 3 conditions, and lag-adjusted cross-correlation coefficients, computed between digitized eye-movement and target signals, were lower among patients. The cross-correlation measure was most sensitive to between-group variability. These results suggest that the impaired SPEM observed in DAT patients reflect degeneration of cortical oculomotor centers, either through inappropriate saccadic intrusions in smooth pursuit as a result of physiologic disinhibition or through effects on attentional processes or both.

Acceleration↗
PubMed1995

Video display terminal very low frequency measurements: the need for protocols in assessing VDT user "dose".

It has been well established that video display terminals (VDTs) which employ the use of a cathode ray tube produce electric and magnetic fields of varying frequencies. Numerous studies have attempted to relate magnetic field exposure from VDTs in the extremely low frequency (ELF) and very low frequency (VLF) bands to adverse pregnancy outcome. Initial studies utilized VDT use time as a surrogate assessment of exposure, while later studies have obtained actual measurements. These measurements have been typically obtained at fixed distances from the screen. While VDT measurement criteria have been established for measuring VDT fields, criteria for the assessment of VDT user exposure has not. VLF magnetic and electric field measurements from approximately 140 and 40 different VDTs, respectively, were obtained over a 3-y period at the following positions: 0.50 m from the vertical centerline of the screen and at the approximate location of VDT user reproductive organs--0.30 m above the seat of the VDT operator in the working position. The measurement results of the two aforementioned locations were compared and demonstrate very little correlation. This lack of correlation indicates that VDT operator exposure assessment criteria are needed to determine any dose-response relationship between VDT electric and/or magnetic fields and adverse health implications.

Abortion, Spontaneous↗
PubMed1981

Three-dimensional computer reconstruction from surface contours for head CT examinations.

A three-dimensional surface reconstruction algorithm based on contour information from anatomic sites as identified on computed tomography examinations is presented. This algorithm efficiently reconstructs the surfaces between the contours using a triangular "tiling" method. A three-dimensional perspective view of the reconstructed surfaces is provided by a gray scale cathode-ray tube computer graphics system. Volume and surface area estimations are provided as a direct results of the surface reconstruction algorithm. Three cases are presented to illustrate the three-dimensional surface reconstruction algorithm.

Brain Neoplasms↗
PubMed2000

Comparison of digital dental X-ray systems with self-developing film and manual processing for endodontic file length determination.

Human skulls were sectioned into 15 sextants. Teeth were then removed and 45 canals were instrumented to their apical foramina. Endodontic files were glued in place at random distances from the apical foramina. Image geometry was maintained by a custom mounting jig. Images were captured with self-developing film, manually processed D-speed film, and a digital radiographic system (Dexis). Digital images were read on a conventional color monitor (cathode ray tube) and a laptop screen (active-matrix liquid crystal display). Fifteen dentists measured the distance from the file tip to the apical foramen of the tooth. Results showed that the measurement error was significantly less for the digital images than for the film-based images. It is likely that these statistical differences may not be of great clinical significance because the digital images could be measured in increments < 0.25 mm.

Analysis of Variance↗
PubMed2000

Comparison between computer-aided diagnosis and radiologists: assessment of pulmonary blood flow on chest radiographs.

To evaluate the performance of a computer-aided diagnosis (CAD) scheme for estimating increased pulmonary blood flow on chest radiographs, we compared computerized assessment with findings by radiologists. Our CAD scheme extracts selectively linear opacities corresponding to vessels in regions of interest (ROIs) in the right upper and lower lung zones on digitized chest radiographs, and then calculates a radiographic index as a physical measure that reflects the area of the extracted opacities in selected ROIs. As a measure of increased pulmonary blood flow, the upper/lower radiographic index ratio was calculated for each patient. Seven radiologists estimated the degree of increased pulmonary blood flow for the same images of ROI sets presented on a cathode-ray tube monitor in a randomized order. Between the normal-pulmonary capillary wedge pressure (PCWP) group and increased-PCWP groups, there was no significant difference in performance between CAD and radiologists (p = 0.105). However, when the normal and mild PCWP groups were compared, the performance of CAD was superior to that of radiologists (p = 0.001). This study indicates that our CAD scheme is promising for quantitative estimation of increased pulmonary blood flow, especially in mild cases.

Diagnosis, Computer-Assisted↗
PubMed2003

Fractal analysis for the assessment of pulmonary blood flow on chest radiographs.

The authors investigated whether fractal analysis can be used with chest radiography for assessment of increased pulmonary blood flow. As a physical measure they used a fractal dimension (FD), which can be used for quantifying texture in selected regions of interest (ROIs). In general, the pulmonary capillary wedge pressure (PCWP) is normally less than 10 mm Hg, the redistribution of pulmonary blood flow reflects PCWP greater than or equal to 10 mm Hg, and the interstitial edema is observed in PCWP greater than or equal to 20 mm Hg. So, the study group consisted of 34 patients with mitral stenosis and 46 patients without mitral stenosis. These patients with and without mitral stenosis were divided into three groups based on their pulmonary capillary wedge pressure (PCWP): normal (n = 38; PCWP, <10 mmHg), mildly increased (n = 26; PCWP, 10 to <20 mmHg), and severely increased (n = 16; PCWP, >or=20 mmHg). ROIs were selected in the right upper and lower lung zones of digitized chest radiographs, and FDs were calculated in each ROI. As a measure of increased pulmonary blood flow, the upper-to-lower FD ratio (FDu/L) was calculated. Five chest radiologists estimated the degree of increased pulmonary blood flow for the same images of ROI sets presented on a cathode ray tube monitor in a randomized order. Between the normal PCWP group and the increased PCWP group, there were no significant differences in utility between the FDu/L and radiologists (P = 0.063). However, when the normal and the mildly increased PCWP groups were compared, the utility of the FDu/L was superior to that of radiologists (P = 0.042). These results indicate that fractal analysis is useful for quantitative estimation of increased pulmonary blood flow, especially in cases of mildly increased pulmonary blood flow.

Female↗
PubMed1987

Reliability and validity of simple photographic plate tests of contrast sensitivity.

Sets of edge and square wave grating photographic plates of varying contrasts were used to measure the mid to low spatial frequency range of the contrast sensitivity function (CSF) of 20 subjects with evident ocular disease and 20 age-matched normal subjects. Both plate tests were shown to have good test-retest reliability and to correlate well with electronic cathode ray tube (CRT) measures of CSF. The edge test, when administered in 2-dB steps of ascending contrast, has optimum sensitivity of 0.70 and specificity of 0.84 for detecting the patient with ocular disease with a fail criterion of less than 38 dB. A measure of edge contrast sensitivity was also shown to be a good predictor of the peak of the CSF, which is shown to be largely independent of the visual acuity of the subject. The 2 c/deg and 4 c/deg plates did not provide more information about the visual difficulties of subjects than the edge test. We advocate the use of an edge test as a simple clinical measure of low spatial frequency contrast sensitivity that provides information about visual dysfunction not provided by a measure of visual acuity.

Adult↗
PubMed1990

Dynamic eye accommodation evoked by apparent distances.

A three-dimensional optometer (TDO), which can measure simultaneously three major ocular functions in a working environment, was used to measure the visual responses of human subjects viewing: (1) actual artworks and (2) corrugation presented by moving random dots on a cathode ray tube (CRT). Measurements were performed in natural viewing conditions on two emmetropic females. Both subjects demonstrated distinct accommodative responses for the stimuli presented at a fixed distance. The results indicate that the accommodation generally shifts in accord with changes of perceived distance. The usefulness of the TDO was demonstrated in these experiments.

Accommodation, Ocular↗
PubMed2003

Repeatability of ocular wavefront measurement.

PURPOSE: To assess the repeatability of measurements of ocular aberrations using wavefront sensing in a small group of observers and to assess the potential effect of measurement error on custom corneal correction due to this variability. METHOD: A Shack-Hartmann wavefront sensor was used to measure the ocular wavefront in nine eyes. Head position was stabilized using a dental bite bar, and the pupil was centred using a cathode ray tube monitor and circular grating. Twenty Shack-Hartmann images were collected for each measurement. Each observer had three sets of measurements taken; the first and the second after careful alignment and the final after regrasping the bite bar in the same position as for the second measurement, but without pupil realignment. The modulation transfer functions for each set were calculated, and the effect of best-aligned custom treatments on the modulation transfer function was estimated. RESULTS: There were highly statistically significant differences in a large number of Zernike modes between the three sets of measurements. The modulation transfer functions calculated for the residual wavefronts after aligned custom treatment were below the diffraction limit. The root mean square wavefront errors were consistently better for the residual wavefronts obtained using the realigned data than using data taken without pupil realignment. CONCLUSIONS: Sequential measurement of ocular aberrations shows statistically significant differences in a large number of Zernike modes. If aberrations determined by a single measurement are to be used in a custom correction, the resulting modulation transfer function is likely to remain below the diffraction limit. Pupil realignment is critical in reduction of the residual root mean square wavefront values to a minimum.

Adult↗
PubMed2003

Comparison of the detectability of high- and low-contrast details on a TFT screen and a CRT screen designed for radiologic diagnosis.

RATIONALE AND OBJECTIVES: To evaluate the detection rate of fine details of a new thin-film transistor (TFT) grayscale monitor designed for radiologic diagnosis, compared with a type of cathode ray tube (CRT) screen used routinely for diagnostic radiology. METHODS: Fifteen radiographs of a statistical phantom presenting low- and high-contrast details were obtained and read out with an Agfa ADC compact storage phosphor system. Each radiograph presented 60 high-density (high-contrast) and 60 low-density (low-contrast) test bodies. Approximately half the test bodies contained holes with different diameters. Observers were asked to detect the presence or absence of a hole in the test body on a 5-point confidence range. The total of 1800 test bodies was reviewed by 5 radiologists on the TFT monitor (20.8 inches; 1536 x 2048 pixels; maximum luminance, 650 cd/m2; contrast, 600:1) and the CRT monitor (21 inches; P45 Phosphor; 2048 x 2560 pixels operated at 1728 x 2304 pixels; maximum luminance, 600 cd/m2; contrast, 300:1). The data were analyzed by receiver-operator characteristic analysis. RESULTS: For high-contrast details, the mean area under the curve rated 0.9336 for the TFT monitor and 0.9312 for the CRT monitor. For low-contrast details, the mean area under the curve rated 0.9189 for the TFT monitor and 0.9224 for the CRT monitor. At P <or= 0.05, no statistically significant difference could be detected between the 2 observational modalities for both (holes in high- and low-contrast disks) types of artifacts. CONCLUSIONS: The TFT screen performs as well as CRT monitors for the detection of fine details in both high- and low-contrast environments. Further studies with images derived from clinical routine are necessary before safely using TFT monitors in clinical practice.

Phantoms, Imaging↗
PubMed2005

Soft-copy reading of digital chest radiographs: effect of ambient light and automatic optimization of monitor luminance.

OBJECTIVE: We sought to evaluate whether soft-copy reading of simulated pulmonary chest lesions is influenced by ambient light and automatic optimization of cathode ray tube (CRT) monitor luminance. MATERIALS AND METHODS: Four types of simulated lesions (nodules, lines, micronodules, and patchy opacities) were superimposed over an anthropomorphic chest phantom. Lesion detection with soft-copy reading was assessed using a high-contrast grayscale 2K CRT monitor under the following conditions: (1) subdued lighting (<50 lux); (2) normal lighting conditions (450 lux) without, and (3) with a sensitivity modulation to automatically adjust the CRT luminance to the increased amount of ambient light. Reading data were analyzed according to receiver operating curve. Significance of differences was tested using an analysis of variance for repeated measures. RESULTS: Ambient room light of 450 lux did not significantly influence the detection of nodules and patchy opacities. However, bright ambient light significantly decreased detection of micronodules (0.60 vs. 0.74) and lines (0.52 vs. 0.66) relative to subdued lighting conditions. Automatic luminance adjustment could compensate the effect of ambient light for the micronodules (0.77) but not for the lines (0.53). CONCLUSION: Bright ambient light significantly decreases detection of small low-contrast structures. This may be partially but not completely compensated by an automatic luminance adaptation.

Data Display↗
PubMed1989

A frameless stereotaxic operating microscope for neurosurgery.

A new system, which we call the frameless stereotaxic operating microscope, is discussed. Its purpose is to display CT or other image data in the operating microscope in the correct scale, orientation, and position without the use of a stereotaxic frame. A nonimaging ultrasonic rangefinder allows the position of the operating microscope and the position of the patient to be determined. Discrete fiducial points on the patient's external anatomy are located in both image space and operating room space, linking the image data and the operating room. Physician-selected image information, e.g., tumor contours or guidance to predetermined targets, is projected through the optics of the operating microscope using a miniature cathode ray tube and a beam splitter. Projected images superpose the surgical field, reconstructed from image data to match the focal plane of the operating microscope. The algorithms on which the system is based are described, and the sources and effects of errors are discussed. The system's performance is simulated, providing an estimate of accuracy. Two phantoms are used to measure accuracy experimentally. Clinical results and observations are given.

Algorithms↗
PubMed2003

Vibrotactile display coding for a balance prosthesis.

Preliminary experiments have demonstrated the potential usefulness of a precursor balance prosthesis that displays the tilt of the subject using tactile vibrators (tactors) which are in contact with the subject's skin. The device consists of a motion sensing system mounted on the head or body whose signals are converted into estimates of head or body tilt. Tilt is displayed to the subject by coding the tilt estimate into signals that are sent to the tactors using one of several schemes. Because full blown, end-to-end balance experiments are relatively time consuming and expensive, and because there are many possible display schemes, we have developed a quantitative means to evaluate the display step separately. We used a modified version of the manual control critical tracking task (CTT) to help us make an initial selection of the more promising vibrotactile display schemes for further evaluation. The classic CTT is a compensatory form of tracking in which the operator attempts to control an increasingly unstable system using a joystick to regulate a tracking error signal (system minus joystick) that is visually displayed as a dot on a cathode ray tube. Our modification added vibrotactile display of the error signal. For a given subject and vibrotactile display scheme, the level of difficulty at which the subjects lost control, called the critical lambda (lambda(c)), was highly repeatable. Four different coding schemes were evaluated using an array of 16 vibrators that were attached to the lower backs of 11 healthy subjects. The first scheme, called interval-based coding, modulated the interval between pulses that were sent to single tactors mounted on the subject's right and left side. A greater tracking error magnitude was displayed as a faster pulse rate. A positive error was displayed on the right side while a negative one was displayed on the left. The remaining three schemes, called position-based coding, used a horizontal row of 14 tactors. Tracking error magnitude was mapped to position of the activated vibrator so that an error near zero corresponded to a vibrator near the center of the back. The three position-based schemes tested used three, four, or seven tactors per side. Averaged over all subjects, the value of lambda(c) for the interval-based scheme was significantly less than it was for each of the three position-based schemes. There was no significant change in lambda(c) as the number of position-based tactors was increased from three to seven per side. The prediction of better actual balance performance using position-based relative to interval-based vibrotactile display was validated by a preliminary study of six normal subjects that compared the body sway produced during quiet standing while providing head tilt estimates using both display modes. Our study provides basic characterization using lambda(c) for several vibrotactile display schemes in human subjects. The quantitative CTT measure of performance can logically be extended to other applications of vibrotactile displays and to other kinds of display schemes used for rehabilitation.

Adolescent↗