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At least 199 records · Page 11Linked to original sources
PubMed1976

Computerised assessment of cardiac pacemaker performance.

The design and use of a PDP 11/40 based automated on-line cardiac pacemaker assessment system is described. One program has been developed for testing pacemakers on the bench and another for implanted pacemaker tests. Either fixed rate or demand pacemakers can be tested. The on-line system is easy and fast to use and is also highly accurate. Parameters extracted are pulse width, rate and pulse energy. In addition, a graphical representation of the patient's ECG and the pacemaker pulse is obtained on a computer graphics terminal.

Computers↗
PubMedDate not supplied

Evaluation of video gray-scale display.

Setting up and maintaining video display monitors properly will help to reduce display variation and improve overall presentation of the radiological image. Display monitor gray-scale characteristics were examined using the SMPTE test pattern. This test pattern may be used as a standard for adjusting brightness and contrast. The controls should be adjusted to display the full dynamic range so that the 5% and 95% signal levels in the pattern are visible. Measured luminance on a laboratory workstation used for radiological perceptual experiments, and on the Siemens CT gray-scale monitor was determined to range from 0.17 to 76.0 nit, and 0.17 to 24.66 nit, respectively. These were compared with the range of approximately 17 to 514 nit for a typical film-viewbox combination. Characteristic curves were determined for both monitors, and CRT gammas were 3.34 and 2.48 for the perceptual workstation and CT console, respectively. The display gamma was determined from fitting luminance data to a log-log plot of luminance versus input gray level. The usefulness of the SMPTE test pattern for visual presentation as well as photometric measurement is demonstrated.

Computer Terminals↗
PubMed1995

Is there a typical VDT patient? A demographic analysis.

BACKGROUND: The use of video display terminals (VDT) in the workplace is growing rapidly. Visual problems associated with computer use are increasing apace. Recognizing and addressing these needs are vital tasks for the optometric practitioner. This paper examines the demographics, prevalence of symptoms, and other work- and vision-related factors among VDT workers. Understanding the characteristics of a typical patient can aid in developing effective treatment protocols. METHODS: Twenty-two optometrists collected data from 324 patients who work on VDT screens for a minimum of 2 hours per day. A questionnaire was used to collect the data. Along with reporting the patients' dry manifest refraction results, the survey instrument also included a self-report of experienced symptoms. RESULTS: The prototypical patient, based on the total subject population, is a 38-year old, mildly myopic female who uses the computer screen about 5 hours per day. Average total VDT work experience is about 5 years. Most of the patients use full-color screens and sit between 21 and 22 inches away from the screen. A variety of visual symptoms is reported, with eyestrain (65 percent) and headaches (42 percent) being the most common complaints. CONCLUSIONS: Between 75 percent (results of this study) and 88 percent (reported by NIOSH) of patients who use a VDT regularly are likely to be symptomatic. This study has helped to identify the "typical" VDT user and the symptoms this user is most likely to report. The next step is to develop a diagnostic and treatment protocol by which optometrists can prescribe for and potentially prevent these computer-related vision problems.

Adolescent↗
PubMedDate not supplied

[Filing and processing systems of ultrasonic images in personal computers].

The paper covers the software pattern for the ultrasonic image filing and processing system. The system records images on a computer display in real time or still, processes them by local filtration techniques, makes different measurements and stores the findings in the graphic database. It is stressed that the database should be implemented as a network version.

Computer Communication Networks↗
PubMed1991

[Hygienic substantiation of work schedules of senior students according to the type of video terminal].

As result of psychological and physiological studies, scientific substantiation is given to the continuous duration of work with two types of video terminals: an Elektronika 15IE-00-14 display and a "Yamaha MSX-1" personal computer in 9(10)-10(11)--to form pupils at the lessons on the basis of informatics and computers, as well as the minimal and optimal duration of intervals.

Adolescent↗
PubMedDate not supplied

Direction constancy in rapidly refreshed video displays.

We studied spatial orientation across saccadic eye movements by adding a disturbance to the system that achieves space constancy. A small target was flickered between 33 and 960 Hz, and it was displaced during saccadic eye movements. The threshold for detecting its displacement was measured. Sensitivity to displacement was almost twice as great when the target was jumped in the direction opposite the eye movement as when it was jumped in the same direction. This would be expected from a partial breakdown of space constancy: The world should seem to move in the direction opposite to an eye movement (when the eyes move to the right, for example, the world would appear to move to the left). Sensitivity to displacement was greater at lower flicker rates. The results imply that both masking and extraretinal signals are important in suppressing the detectability of target displacements during saccades, and that flicker on video display terminal may distort space perception. These and other results lead to a recommendation that video terminals be refreshed at least 120 times/s.

Computer Terminals↗
PubMed1992

Daily monitoring and correction of radiation field placement using a video-based portal imaging system: a pilot study.

We have developed a video-based portal imaging system for radiotherapy localization. The system can acquire high quality portal images automatically using short (1-3 monitor unit) irradiations and immediately display the images. The major advantage of the imaging system is that it can be used routinely to check and correct patient positioning before much of the daily irradiation has been delivered. The portal imaging system has been used in a pilot study to monitor five patients during each of their daily treatments. The study has shown that: (i) image quality is sufficiently high to detect discrepancies in field placement from that prescribed on the simulator film; (ii) discrepancies in field placement occur frequently; and, (iii) routine correction of patient and block positioning can reduce the size of these discrepancies. This is the first time that field placement in radiation therapy has been checked and corrected routinely, before the treatment irradiation. However, limitations in the size of the field of view and in the methods of extracting and presenting the geometric information to the users limits the clinical utility of the imaging system. Solutions to these limitations are currently under development.

Computer Terminals↗
PubMedDate not supplied

[Pregnancy in women working on video terminal units].

Only a small proportion of pregnancy failures could be explained by simple genetic or clear--cut environmental/occupational factors. Adverse reproductive outcomes (spontaneous abortion, preterm delivery, low birth weight and congenital malformations), have been reported in a certain number of retrospective studies which were designed to examine the possible role of occupation and working or living conditions and pregnancy outcome. Future prospective projects should assess the (non)existence of the relationship between radiological risks and job stress with pregnancy outcome. Future prospective projects should assess the (non)existence of the relationship between radiological risks and job stress with pregnancy outcome among female video terminal operators.

Abortion, Spontaneous↗
PubMed1994

Computer-assisted 3D reconstruction of the terminal branches of the cerebral arteries. I. Anterior cerebral artery.

We present a three-dimensional anatomical computer model of the terminal branches of the anterior cerebral artery, acquired from equidistant serial anatomical slices of three brains. The reconstructions provide a clear picture from all angles of the complicated course of the terminal branches of the cerebral arteries, which can help to identify them on conventional and magnetic resonance angiography. Our rendition of the cerebral arteries can also be matched with CT, MR or PET images to indicate the areas of extension of individual branches, allowing neuromorphological and functional correlations.

Adult↗