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Evaluation of computer display systems using digital test patterns.

Two digital test patterns are used to evaluate computer video display systems. One pattern consists of linear and logarithmic gray-scale wedges, blocks of constant brightness, and horizontal and vertical bar patterns. The other is a cross-hatch bar pattern. These patterns are used to assess display systems' gray scale, resolution, and spatial linearity. Microdensitometry measurements were performed to determine brightness uniformity, spatial resolution, and to relate optical density to exposure. These test patterns, used qualitatively, are useful in the routine adjustment and quality control of digital systems. The precise quantitative characterization of a display system is important in research applications involving image processing.

Computers↗

A new system for computer aided dental identification in mass disasters.

In recent years, several computer programs for dental identification in mass disasters have been developed. Unfortunately, it may be difficult to get access to such programs. The Norwegian police presently utilizes a text retrieval program, NOVA*STATUS, for detection work. This program is based on the British STATUS ONE program, and it enables the user to find from a large pool of postmortem dental registration one or several sets containing specific information about one tooth or several teeth. The complete relevant set(s) can be displayed for visual examination and comparison. A coding system for dental information has been developed as well as a system for interrogating the computer. This system and its efficiency have been tested on a simulated small scale disaster where various well-known difficulties in dental identification were included.

Computers↗

A cone beam computed tomography system for true 3D imaging of specimens.

A system for 3D cone beam computed tomography has been developed, consisting of a microfocus x-ray source and x-ray image intensifier coupled to a CCD camera. Full width at half maximum resolving power has been experimentally measured to be 70 microns when imaging 10 mm diameter objects. The 3D nature of the resulting image data can be used to visualize internal structure and compute parameters such as volume, surface area, and surface/volume orientation.

Animals↗

Virtual bronchoscopic navigation system shortens the examination time--feasibility study of virtual bronchoscopic navigation system.

Computed tomography (CT)-guided transbronchial biopsy (TBB) using an ultrathin bronchoscope with simulation by virtual bronchoscopy (VB) is effective for diagnosing small peripheral pulmonary lesions. However, we occasionally lose the proper bronchi to the lesion when a bronchoscope is inserted into peripheral bronchi with severe rotation. To overcome this problem, the virtual bronchoscopic navigation system that can display real-time VB images during TBB procedures in comparison with actual bronchi has been developed. We evaluated the usefulness of the virtual bronchoscopic navigation system for CT-guided TBB using an ultrathin bronchoscope (navigation method) to diagnose small peripheral pulmonary lesions, and compared the results to those with previous method that uses VB images in a simulation (simulation method). We performed CT-guided TBB using an ultrathin bronchoscope for 69 patients with 71 small peripheral pulmonary lesions (mean diameter, 13.7 mm) between November 2002 and November 2005 with the navigation method. CT-guided TBB with the navigation method was performed safely without any serious complications for all patients. Mean time to the initial scan, time to the first biopsy and total examination time were 5.3, 8.5 and 24.5 min, respectively. Fifty lesions (70%) were diagnosed by this procedure. Compared to simulation method, diagnostic sensitivity was higher in the navigation method, but the difference was not significant. However, the time to the first biopsy and total examination time were significantly shorter in the navigation method than in the simulation method (p<0.05). In summary, the virtual bronchoscopic navigation system was safely used, effective for diagnosing small peripheral pulmonary lesions, and useful for shortening the examination time of CT-guided TBB using an ultrathin bronchoscope.

Aged↗

Lung function analysis and optimization during artificial ventilation. A personal computer-based system.

In an intensive care unit a personal computer (PC) application for lung function analysis has been in use for 5 years. The PC system is applied to measure conventional and new parameters for diagnosis and therapy. The primary goal was to find parameters which could be used as optimization indices in optimal control systems for mechanical ventilation. Another clinical application of the PC system was as an automatic controller that stabilizes end-tidal CO2 concentration. The controller and the next application, the optimizer, could be integrated into an optimal control system. Such a system is described and a simulation trial of the integrated structure has demonstrated the potential.

Humans↗

The dynamic spatial reconstructor: a computed tomography system for high-speed simultaneous scanning of multiple cross sections of the heart.

A new generation whole-body computed tomography system has been developed to provide accurate visualization and measurement of the vital functions of the heart, lungs, and circulation. This dynamic spatial reconstructor system (DSR) provides stop-action (.01-sec), rapidly sequential (60-per-second), synchronous volume (240 simultaneous adjacent 1-mm-thick transaxial sections) reconstructions and display of the full anatomic extents of the internal and external surfaces of the heart throughout successive cardiac cycles, and will permit visualization of the three-dimensional vascular anatomy and circulatory functions in all regions of the body of patients with cardiovascular and other circulatory disabilities.

Animals↗

[The development of an automated system for computing the "standard" values of the economic loss brought by one case of infectious disease].

An original and technically realizable system for the determination of the values of economic damage produced by a single case of an infectious disease has been developed, based on a concrete socio-economic analysis. The system has been realized with the use of an IBM PC/AT by means of the Econ program module developed in the SuperCalc-4 tabulated processor program environment. The use of the average socio-epidemiological, national economic and demographic statistical data has made it possible to calculate the "standard" values of the economic damage produced by a single case of 15 infectious diseases (total average, as well as for different groups of patients and measures). Analysis of the values thus obtained shows their, on the average, 1.25-fold growth, as well as their considerable variability reflecting the clinico-epidemiological nature of infectious diseases.

Absenteeism↗

Investigating extended regulatory regions of genomic DNA sequences.

MOTIVATION: Despite the growing volume of data on primary nucleotide sequences, the regulatory regions remain a major puzzle with regard to their function. Numerous recognising programs considering a diversity of properties of regulatory regions have been developed. The system proposed here allows the specific contextual, conformational and physico-chemical properties to be revealed based on analysis of extended DNA regions. RESULTS: The Internet-accessible computer system RegScan, designed to analyse the extended regulatory regions of eukaryotic genes, has been developed. The computer system comprises the following software: (i) programs for classification dividing a set of promoters into TATA-containing and TATA-less promoters and promoters with and without CpG islands; (ii) programs for constructing (a) nucleotide frequency profiles, (b) sequence complexity profiles and (c) profiles of conformational and physico-chemical properties; (iii) the program for constructing the sets of degenerate oligonucleotide motifs of a specified length; and (iv) the program searching for and visualising repeats in nucleotide sequences. The system has allowed us to demonstrate the following characteristic patterns of vertebrate promoter regions: the TATA box region is flanked by regions with an increased G+C content and increased bending stiffness, the TATA box content is asymmetric and promoter regions are saturated with both direct and inverted repeats. AVAILABILITY: The computer system RegScan is available via the Internet at http://www.mgs.bionet.nsc. ru/Systems/RegScan, http://www.cbil.upenn.edu/mgs/systems/r egscan/.

Algorithms↗

Building a cytology report database: a computer-assisted system for documentation, evaluation and hospital-wide recall of haematological biopsy reports.

Owing to an increasing number of biopsies from different organ systems in our institution and referring institutions there was need to develop a computer-based system to improve documentation, analysis and reports of pathological findings, as well as speed of transmission of information in a clinical haematology/oncology unit. As terminals connected to a central minicomputer are located on all wards of our hospital, we have now provided a faster way of moving information from the cytology reporting site to all hospital departments. Using the hospital's minicomputer we developed an easy-to-use system based on five different codes for each cytological specimen: organ biopsied, quality of specimen, cytological diagnosis including information as to status of patient (i.e. pretherapy), and an additional code describing the degree of remission obtained after chemotherapy of acute leukemias. After microscopic analysis of the specimen these five codes are read into a terminal; minutes after the diagnosis is made, a short version of the report can be accessed from all wards in the hospital.

Biopsy↗

SLIPS. A data base system for computer storage and analysis of phonological errors.

The analysis of phonological errors made by normal individuals (slips of the tongue) and brain-damaged patients (paraphasias) is a challenging problem. SLIPS is an experimental data base system for computer storage and analysis of such errors. This paper introduces SLIPS and describes its main features. Some of the problems that arise in analyzing phonological error data are explained, and examples of their solution are presented.

Computers↗

Changes in breast cancer detection and mammography recall rates after the introduction of a computer-aided detection system.

BACKGROUND: Computer-aided mammography is rapidly gaining clinical acceptance, but few data demonstrate its actual benefit in the clinical environment. We assessed changes in mammography recall and cancer detection rates after the introduction of a computer-aided detection system into a clinical radiology practice in an academic setting. METHODS: We used verified practice- and outcome-related databases to compute recall rates and cancer detection rates for 24 Mammography Quality Standards Act-certified academic radiologists in our practice who interpreted 115,571 screening mammograms with (n = 59,139) or without (n = 56,432) the use of a computer-aided detection system. All statistical tests were two-sided. RESULTS: For the entire group of 24 radiologists, recall rates were similar for mammograms interpreted without and with computer-aided detection (11.39% versus 11.40%; percent difference = 0.09, 95% confidence interval [CI] = -11 to 11; P =.96) as were the breast cancer detection rates for mammograms interpreted without and with computer-aided detection (3.49% versus 3.55% per 1000 screening examinations; percent difference = 1.7, 95% CI = -11 to 19; P =.68). For the seven high-volume radiologists (i.e., those who interpreted more than 8000 screening mammograms each over a 3-year period), the recall rates were similar for mammograms interpreted without and with computer-aided detection (11.62% versus 11.05%; percent difference = -4.9, 95% CI = -21 to 4; P =.16), as were the breast cancer detection rates for mammograms interpreted without and with computer-aided detection (3.61% versus 3.49% per 1000 screening examinations; percent difference = -3.2, 95% CI = -15 to 9; P =.54). CONCLUSION: The introduction of computer-aided detection into this practice was not associated with statistically significant changes in recall and breast cancer detection rates, both for the entire group of radiologists and for the subset of radiologists who interpreted high volumes of mammograms.

Breast Neoplasms↗

Evaluation of a prostate biopsy strategy for cancer detection using a computer simulation system with virtual needle biopsy for three-dimensional prostate models.

AIM: We evaluated a prostate biopsy strategy for cancer detection using a computer simulation system with virtual needle biopsy for three-dimensional (3D) prostate models. METHODS: Two 3D prostate models with a volume of 25 cc or 50 cc were constructed from computed tomographic images of radical prostatectomy specimens. The peripheral zone (PZ) and transition zone (TZ) were arranged in the prostate models according to the anatomical information. Four thousand patterns of cancer lesions were automatically inserted into each prostate model with a proportion of 75% in PZ and 25% in TZ. Average hit rates (AHR) in prostate models were evaluated both with an increased number of biopsy cores and various angles of virtual needle biopsy. The influence of adding secondary tumors for hit rates was also evaluated. RESULTS: For both sizes, the laterally angled biopsy in 4-8 core biopsy schemes showed higher AHR than the vertical plane biopsy, while the vertical plane biopsy in 10-18 core biopsy schemes showed higher AHR than the laterally angled biopsy. A higher number of biopsy cores increased the AHR of secondary tumors. CONCLUSIONS: Our results suggest that it is important in prostate cancer detection to change the needle placement according to the number of biopsy cores and the size of the prostate.

Biopsy, Needle↗

In-silico screening of high production volume chemicals for mutagenicity using the MCASE QSAR expert system.

Computational screening is suggested as a way to set priorities for further testing of high production volume (HPV) chemicals for mutagenicity and other toxic endpoints. Results are presented for batch screening of 2484 HPV chemicals to predict their mutagenicity in Salmonella typhimurium (Ames test). The chemicals were tested against 15 databases for Salmonella strains TA100, TA1535, TA1537, TA97 and TA98, both with metabolic activation (using rat liver and hamster liver S9 mix test) and without metabolic activation. Of the 2484 chemicals, 1868 are predicted to be completely nonmutagenic in all of the 15 data modules and 39 chemicals were found to contain structural fragments outside the knowledge of the expert system and therefore suggested for further evaluation. The remaining 616 chemicals were found to contain different biophores (structural alerts) believed to be linked to mutagenicity. The chemicals were ranked indescending order according to their predicted mutagenic potential and the first 100 chemicals with highest mutagenicity scores are presented. The screening result offers hope that rapid and inexpensive computational methods can aid in prioritizing the testing of HPV chemicals, save time and animals and help to avoid needless expense.

Animals↗

Amphibolic drug combinations: the design of selective antimetabolite protocols based upon the kinetic properties of multienzyme systems.

Computer simulation of a simple biochemical pathway containing a divergent branch has been used to study the interaction of two inhibitors that straddle the branch point. The combined effects of the two sequentially acting inhibitors could be synergistic, additive, or antagonistic, depending upon the regulation of the pathway. Factors that influenced the interaction included relative Vmax and Km values for the competing enzymes, the sink capacity of the system (i.e., the capacity of the system for eliminating the shared intermediate in relation to its capacity for producing it), the competitive or noncompetitive nature of the second inhibitor, and the presence or absence of feedback in the system. In certain cases, a two-fold change in the Vmax value of one of the competing enzymes was sufficient to change the interaction from synergistic to antagonistic. The existence of such drug combinations (which this article terms amphibolic combinations) means that it is possible in principle to identify binary drug combinations that will be synergistic against a tumor cell but antagonistic against normal cells. Identification of amphibolic drug combinations should be a means of designing more selective chemotherapy.

Antineoplastic Combined Chemotherapy Protocols↗

Microcomputer programs for DNA sequence analysis.

Computer programs are described which allow (a) analysis of DNA sequences to be performed on a laboratory microcomputer or (b) transfer of DNA sequences between a laboratory microcomputer and another computer system, such as a DNA library. The sequence analysis programs are interactive, do not require prior experience with computers and in many other respects resemble programs which have been written for larger computer systems (1-7). The user enters sequence data into a text file, accesses this file with the programs, and is then able to (a) search for restriction enzyme sites or other specified sequences, (b) translate in one or more reading frames in one or both directions in order to find open reading frames, or (c) determine codon usage in the sequence in one or more given reading frames. The results are given in table format and a restriction map is generated. The modem program permits collection of large amounts of data from a sequence library into a permanent file on the microcomputer disc system, or transfer of laboratory data in the reverse direction to a remote computer system.

Base Sequence↗

[Computerised three-dimensional surgical simulator. Introduction and precision analysis of a new system].

Computed tomography (CT)-based anatomic three-dimensional (3D) models have become important tools in oral maxillofacial surgery. There are three problems involved in the precise transfer of the experience gained and the results of simulation surgery to the patient: (1) 3D models have no precise reference points; (2) it is difficult to measure translations three-dimensionally; and (3) exact transfer to the patient intraoperatively is impossible. We have introduced a new system which solves these problems. In the first step 3D dental arches are replaced by plaster models, using an occlusal device with three radioopaque hemispheres as reference. A computerised electromagnetic tracker makes 3D measurements possible during simulated surgery, and a newly developed transfer system with a neurosurgical head frame to provide stable anchorage is used for positioning during surgery. We present our experience with this system in 15 orthognathic patients undergoing bimaxillary surgery. With the 3D computerised simulation surgery and model operation transfer system (3D-COSMOS) the dental arches can be replaced with a mean accuracy of 0.03 mm. The 3D translations of jaw segments can be measured precisely (0.11 mm) and simultaneously at the osteotomy line and the teeth. The new jaw position is transferred mechanically with a precision of 0.05 mm. Operation time is prolonged only by 15 min.

Cephalometry↗