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Computer systems for three-dimensional diagnostic imaging: an examination of the state of the art.

This survey reviews three-dimensional (3D) medical imaging machines and 3D medical imaging operations. The survey is designed to provide a snapshot overview of the present state of computer architectures for 3D medical imaging. The basic volume manipulation, object segmentation, and graphics operations required of a 3D medical imaging machine are described and sample algorithms are presented. The architecture and 3D imaging algorithms employed in 11 machines which render medical images are assessed. The performance of the machines is compared across several dimensions, including image resolution, elapsed time to form an image, imaging algorithms employed in the machine, and the degree of parallelism employed in the architecture. The innovation in each machine, whether architectural or algorithmic, is described in detail. General trends for future developments in this field are delineated and an extensive bibliography is provided.

Computer Systems↗

The role of pharmacy computer systems in preventing medication errors.

OBJECTIVE: To describe the controversies and review the evidence about computer-aided prospective drug utilization review (PDUR) systems. DATA SOURCES: MEDLINE search of the literature. STUDY SELECTION: Published studies of the effectiveness of computer-aided prescription screening. DATA SYNTHESIS: One randomized, controlled trial and four nonrandomized studies constitute the evidence base. The five studies are inconclusive with respect to whether computer-aided prescription screening causes health care providers to take action, either because of a no difference finding or because there was no comparison group. In the one randomized, controlled trial, a substantial number of actions were taken by the control group whose members did not receive alerts. No study evaluated the total effect of screening by in-store and payer (online) systems. Specific research recommendations are made to increase the evidence base. CONCLUSION: Limited and inconclusive evidence about whether these systems are effective and what system features are optimal may explain the wide variation among systems in terms of what problems are screened and may also explain clinicians' uncertainty about their value. A comprehensive national research agenda for reducing medical errors should include research on the effectiveness of computer-aided PDUR.

Computer Systems↗

[Data processing computer system for evaluation of health effects due to occupational diseases diagnosed in Poland].

General consequences of occupational diseases for both employees and the country's economy have been known for many decades. Nevertheless there were no legal instruments and financial means to carry out studies leading to a comprehensive evaluation of health effects induced by occupational diseases diagnosed in Poland. Only recently, the legal basis has been provided by the revision of the regulations on occupational diseases (Official Journal of the Ministry of Health and Social Welfare no 9, heading 51, 1989), and the financial means allocated according to the Governmental Strategic Programme (SPR-1) for the years 1995-1998. The objectives of the study and the results obtained have been presented in another publication. Here the authors concentrated on some aspects of data collection and their analysis. An essential element in the establishment of data base on health effects of occupational diseases was its integration, namely the number of diagnosed occupational disease had to correspond with the entity in the Register of Occupational Diseases. Such an approach helped to avoid including in the base all metrical data, as information on effects of occupational diseases was collected exclusively for persons with detected and diagnosed occupational disease, which had to be previously placed in the Register of Occupational Diseases. The correctness of data input and the data analysis were carried out outside the Paradox system. The analysis of histograms of characteristics under study and the explanation of departing values were employed to evaluate the freedom from bias, and the statistical package for social sciences (SPSS) was used to analyse the data.

Computer Systems↗

Computer systems analysis of the cardiovascular mechanisms of reentry orthostasis in astronauts.

Reentry orthostasis secondary to a prolonged exposure to microgravity is a common problem among astronauts. However, the physiologic mechanisms are poorly understood due to the many control systems involved. In this study an advanced computer model of cardiovascular functioning was employed in a systems analysis approach to clarify the relative importance of some of the adaptive physiologic processes engaged when humans return from space. After simulation of the conditions of zero gravity for one month, the model predicted that the change in capacitance of the lower extremity veins resulting from a loss of external fluid forces in the dehydrated extracellular compartment was the dominant mechanism associated with reentry orthostasis. This condition appears accentuated in women due to their inherent lower center of gravity and proportionately larger mass in the lower extremities.

Adaptation, Physiological↗

An objective computer system for the quantification of artery stenoses.

We have developed a low cost, clinically usable system for the objective assessment of the severity of coronary artery stenoses from single view angiograms. The system is based on a desktop computer with incorporated frame grabber. Images are captured by means of a video camera. The user selects a region of interest which encompasses the stenosis. Facilities are provided for automatic or manual definition of the artery centre line and edges. The computer then calculates the artery diameter and cross-sectional area by videodensitometry along profile lines which are orthogonal to the long axis of the artery. These results can be expressed numerically as a percentage stenosis when compared to a normal region of the artery. The image is corrected for geometric distortion using a grid test object. The image grey scale is corrected by means of a ramp test object such that a pixel value is proportional to the attenuator thickness. The ramp is placed on the patient during the X-ray examination and an iterative technique has been developed for subtracting the underlying structures from the superimposed ramp image. The system has been assessed using test objects constructed in Perspex which simulate arteries of known cross-sectional area and stenoses of known severity.

Algorithms↗

A computer system for continuous long-term recording, processing, and analysis of physiological data of brain injured patients in ICU settings.

The objective of this project was to assemble and test a computer-based system for continuous long-term physiological data acquisition. The system would be used to study short-term (heart rate variability) and long-term (circadian rhythms) dynamics of physiological parameters in severely brain injured patients in ICU settings. A system has been built using open-source software and the Linux operating system as the platform. The system consists of three main parts: data acquisition, processing and analysis. The system was tested in ICU and experimental settings for long periods of time (up to 10 days of non-stop recording). The system appeared to function properly and accurately. Samples of the data according to the stages of acquisition-analysis process are presented in the paper. Avenues for the system use and development are discussed.

Brain Injuries↗

Effect of the drug-excipient ratio in matrix-type-controlled release systems: computer simulation study.

The main objective of this work is to study the drug release behavior from inert matrix systems by using computer simulation. This study allowed us to propose a new statistical method to evaluate the drug percolation threshold as a function of the exposed surface area of the device. The matrix system was simulated as a simple cubic lattice. The sites of the lattice were randomly occupied at various drug-excipient ratios. By simulating a diffusive process, the drug was delivered from the matrix system. The obtained release profiles were fitted to two different models: near the excipient percolation threshold, the square root of the time was well fitted, whereas close to (but above) the drug percolation threshold, the power law described accurately the release data. A relationship between the initial drug load and the amount of drug trapped inside the matrix system at infinite time was found. This relationship was conveniently described by an error function. Percolation thresholds in the matrix systems were determined from the latter relationship by using a nonlinear regression method. The assessment of percolation thresholds depends on the exposed surface area of the matrix systems. Moreover, estimated percolation thresholds were in agreement with the predicted values stated in the percolation theory.

Algorithms↗

Self-administered psychotherapy for depression using a telephone-accessed computer system plus booklets: an open U.S.-U.K. study.

OBJECTIVE: To evaluate the efficacy and acceptability of a self-help program for mild-to-moderate depression that combined treatment booklets and telephone calls to a computer-aided Interactive Voice Response (IVR) system. METHOD: In an open trial, 41 patients from Boston, Massachusetts; Madison, Wisconsin; and London, England, used COPE, a 12-week self-help system for depression. COPE consisted of an introductory videotape and 9 booklets accompanied by 11 telephone calls to an IVR system that made self-help recommendations to patients based on information they entered. RESULTS: All 41 patients successfully completed the self-assessment in the booklets and telephone calls; 28 (68%) also completed the 12-week self-help program. Hamilton Rating Scale for Depression (HAM-D) and Work and Social Adjustment scores improved significantly (41% and 42% mean reduction in the intent-to-treat sample, respectively, p < .001). Eighteen (64%) of the 28 completers were considered responders on the basis of > or = 50% reduction in their HAM-D scores. There was a higher percentage of completers in the pooled U.S. sites (82% vs. 43%), and U.S. completers improved more than those in the United Kingdom (73% vs. 43% were responders). Most (68%) of the calls were made outside usual office hours, Monday-Friday, 9:00 a.m. to 5:00 p.m. Expectation of effectiveness and time spent making COPE calls (more treatment modules) correlated positively with improvement over 12 weeks. Mean call length for completers was 14 minutes. CONCLUSION: A self-help system comprised of a computer-aided telephone system and a series of booklets was used successfully by people with mild-to-moderate depression. These preliminary results are encouraging for people who cannot otherwise access ongoing, in-person therapy.

Adult↗

A computer system for neurosurgical patient monitoring.

The variables monitored in intensive care units are generally late indicators of neurologic deterioration. A system based on a LINC-8 computer was therefore developed for on-line monitoring of evoked potentials, electroencephalography (EEG), and transcranial and transthoracic impedances as well as conventional parameters. Somatosensory evoked potentials are recorded at either 30 min or 1 h intervals. One minute epochs of EEG are analyzed every 10 min using a peak-detection algorithm. Impedances and conventional parameters are also monitored at 10 min intervals. In a study of 50 patients, the technical feasibility of this type of monitoring with a small laboratory computer has been demonstrated. In some instances, evoked potentials and EEG show changes prior to detectable neurologic changes. The study suggests that this type of monitoring can provide a valuable adjunct for evaluation of physiologic function in neurosurgical intensive care.

Afferent Pathways↗