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Results for “Computer Peripherals”

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At least 307 records · Page 17Linked to original sources
PubMed1996

Distal radius: in vivo assessment with quantitative MR imaging, peripheral quantitative CT, and dual X-ray absorptiometry.

PURPOSE: To evaluate in vivo the relationship between magnetic resonance (MR) imaging relaxation time and bone mineral density (BMD) at the distal radius. MATERIALS AND METHODS: The 1/T2* MR imaging relaxation rates and dual X-ray absorptiometry (DXA) measurements were evaluated in the trabecular bone of the distal 5 cm of the radius in 14 healthy premenopausal women and 11 healthy postmenopausal women and in 11 women with osteoporosis. Trabecular and total BMD were measured with peripheral quantitative computed tomography (CT). RESULTS: In healthy women, 1/T2* values and trabecular BMD at peripheral quantitative CT were significantly correlated but 1/T2* and total BMD were not. Statistically significant (P = .03) correlations between 1/T2* and DXA were found only in the most distal area covered with DXA. The 1/T2* values were more closely correlated with age and showed higher relative annual decreases (0.47%-0.81%) than peripheral quantitative CT (0.20%-0.59%) or DXA (0.10%-0.39%). Pre- and postmenopausal healthy subjects could be distinguished only with MR imaging, and postmenopausal healthy and osteoporotic subjects only with CT and DXA. CONCLUSION: MR imaging relaxation rates correlate well with trabecular BMD in vivo.

Absorptiometry, Photon↗
PubMed1995

The cumulative verification image analysis tool for offline evaluation of portal images.

PURPOSE: Daily portal images acquired using electronic portal imaging devices contain important information about the setup variation of the individual patient. The data can be used to evaluate the treatment and to derive correction for the individual patient. The large volume of images also require software tools for efficient analysis. This article describes the approach of cumulative verification image analysis (CVIA) specifically designed as an offline tool to extract quantitative information from daily portal images. METHODS AND MATERIALS: The user interface, image and graphics display, and algorithms of the CVIA tool have been implemented in ANSCI C using the X Window graphics standards. The tool consists of three major components: (a) definition of treatment geometry and anatomical information; (b) registration of portal images with a reference image to determine setup variation; and (c) quantitative analysis of all setup variation measurements. The CVIA tool is not automated. User interaction is required and preferred. Successful alignment of anatomies on portal images at present remains mostly dependent on clinical judgment. Predefined templates of block shapes and anatomies are used for image registration to enhance efficiency, taking advantage of the fact that much of the tool's operation is repeated in the analysis of daily portal images. RESULTS: The CVIA tool is portable and has been implemented on workstations with different operating systems. Analysis of 20 sequential daily portal images can be completed in less than 1 h. The temporal information is used to characterize setup variation in terms of its systematic, random and time-dependent components. The cumulative information is used to derive block overlap isofrequency distributions (BOIDs), which quantify the effective coverage of the prescribed treatment area throughout the course of treatment. Finally, a set of software utilities is available to facilitate feedback of the information for treatment plan recalculation and to test various decision strategies for treatment adjustment. CONCLUSIONS: The CVIA tool provides comprehensive analysis of daily images acquired with electronic portal imaging devices. Its offline approach allows characterization of the nature of setup variation for the individual patient that would have been difficult to deduce using only a few daily or weekly portal images. Distribution of the tool will help establish an important database of setup variation from many clinics. The information derived from CVIA can also serve as the foundation to integrate treatment verification, treatment planning, and treatment delivery.

Computer Peripherals↗
PubMed2000

Suitability of the general-purpose graphic printer as an image output device for digital dental x-ray images.

OBJECTIVES: The purpose of this study was to evaluate the suitability of the general-purpose graphic printer as an image output device for digital dental x-ray images. METHODS: The image quality as obtained by a thermal printer and by a dye sublimation printer was investigated. A grid pattern image was used to check parallelism and verticality of lines in each hard copy. A step-wedge image was printed with each printer, and the optical density, gradient, and root mean square granularity were compared. Depiction ability was also compared by using test images, including small signals. RESULTS: All of the lines were parallel and vertical on hard copies of both printers. The dye sublimation printer showed better results on optical density, gradient, root mean square granularity, and depiction ability. CONCLUSION: The dye sublimation printer produces images of the depiction ability comparable to the cathode ray tube display and seems suitable as an image output device for digital dental x-ray images.

Coloring Agents↗
PubMed1991

Computer-aided cell colony counting.

Counting cell colonies is a tedious task when performed with the light microscope. Moreover, unless strict double-blind protocols are adhered to, biased counts are difficult to avoid. Presented here is a computer software application that performs accurate, reproducible cell colony counts with a minimum of user generated bias. The application is based upon the Apple IICX computer system with Image software and AppleScan. Colonies are grown on 24-well plates and prepared in such a way as to permit good quality scanning. The scans are then transferred to Image and the individual colonies in each well are counted. Good correlation with counts done by light microscopy is achieved.

Clone Cells↗
PubMed1993

User interfaces: where the rubber meets the road.

Today's users face a dizzying array of interface tools from which to choose. Keyboard, mouse, voice or touchscreen, Windows, pull-down menus, point-and-click--so many choices, but which is best?

Commerce↗
PubMed1995

[The value of 3D video endoscopy for surgical procedures].

We discuss the problems of spatial perception that arise by the transmission of endoscopic surgery by traditional video systems and analyse the improvements that can be achieved by two- und three-dimensional systems. Starting with a description of the physics of vision and the principles of two- and three-dimensional imaging, we demonstrate the importance of optimal adaptation of technology to the natural perception processes of the observer. In this context we review critically the technology that is presently available. Only stereoscopic video technology with 'shutter glasses' provides the observer with the spatial information that is of such decisive importance for minimally invasive surgery. Finally we discuss new technical developments that further improve three-dimensional vision in endoscopy, such as a 3D video module that is small enough to be used intracorporally.

Computer Peripherals↗
PubMedDate not supplied

Cables.

If you want to control your own computer installation, get the satisfaction of doing your own maintenance, and compensate for an inept or uninformed vendor, the information in this article will help you achieve these ends. Good luck and good cabling!

Computer Peripherals↗
PubMed1990

PNSCROLL, a software package for graphical interactive analysis of single channel patch clamp currents and other binary file records: under mouse control.

The PNSCROLL program has been specifically developed for interactively scrolling through binary data files under mouse control, in order to analyse single channel current records and printout, or plot, records and histograms of currents. PNSCROLL requires the use of a Microsoft Mouse and runs on an IBM or IBM-compatible microcomputer operating under MS DOS, ideally with 256K EGA or VGA graphics card and colour display. It will print on Epson dot matrix printers and plot records and histograms on HP plotters and LaserJet laser printers.

Computer Graphics↗
PubMed1995

Three-dimensional uniform grid modeling of electrical defibrillation on a data parallel computer.

Finite element modeling has played an increasingly important role in the study of defibrillation. In order to model well the complex anatomical details, a large number of elements are required in the finite element grid, leading to a large set of equations that often cannot be solved effectively with the computational power of conventional computers. In this paper, we describe the use of a data parallel computer to provide the memory and reduction in solution time for solving these large finite element problems. Using a uniform grid and a nodal assembly technique, the discretized problem domain can be mapped efficiently to the parallel computer, allowing the solution of problems with over two million unknowns. The finite element algorithm for a three-dimensional inhomogeneous anisotropic body is described together with its parallel implementation. Test results for a canine torso model constructed from CT images are also presented.

Algorithms↗
PubMed2001

Minimal data sets.

Explore the source record for details and available documents.

Data Collection↗
PubMed1997

Peripheral measurement techniques for the assessment of osteoporosis.

Peripheral measurement techniques have been the first to be developed for the assessment of osteoporosis, and they remain useful. Besides traditional approaches such as radiographic absorptiometry (RA), radiogrammetry, and single-photon absorptiometry (SPA), new peripheral approaches have been developed that offer powerful ways to assess skeletal status in osteoporosis. These include single x-ray absorptiometry (SXA), peripheral dual x-ray absorptiometry (pDXA), peripheral quantitative computed tomography (pQCT), quantitative ultrasound (QUS) techniques, and magnetic resonance imaging (MRI) approaches. This review describes the current role of peripheral imaging techniques vis-à-vis their central imaging counterparts. Peripheral measurement techniques are attractive because equipment cost is substantially lower, radiation exposure is small, and the devices require less space and sometimes are even portable. Additionally, QUS and MRI offer the potential to measure aspects of bone status beyond the limits of bone densitometry. Peripheral techniques represent important diagnostic methods for the assessment of osteoporosis.

Absorptiometry, Photon↗
PubMed2003

Exploration of virtual mazes by rhesus monkeys (Macaca mulatta).

A chasm divides the huge corpus of maze studies found in the literature, with animals tested in mazes on the one side and humans tested with mazes on the other. Advances in technology and software have made possible the production and use of virtual mazes, which allow humans to navigate computerized environments and thus for humans and nonhuman animals to be tested in comparable spatial domains. In the present experiment, this comparability is extended even further by examining whether rhesus monkeys (Macaca mulatta) can learn to explore virtual mazes. Four male macaques were trained to manipulate a joystick so as to move through a virtual environment and to locate a computer-generated target. The animals succeeded in learning this task, and located the target even when it was located in novel alleys. The search pattern within the maze for these animals resembled the pattern of maze navigation observed for monkeys that were tested on more traditional two-dimensional computerized mazes.

Animals↗
PubMed2003

Joystick acquisition in tufted capuchins (Cebus apella).

A number of nonhuman primate species have demonstrated the ability to use a joystick to control a cursor on a computer screen, yet the acquisition of this skill has not been the focus of systematic inquiry. Here, we examined joystick acquisition in four tufted capuchins under two directional relationships of joystick movement and resultant cursor displacement, isomorphic and inverted. To document the natural history of the acquisition of this skill, we recorded the development of visual tracking of the cursor and body tilting. Rates of acquisition were comparable between the two conditions. After mastering the task in one condition, subjects remastered the task at an accelerated rate in the opposing condition. All subjects significantly increased or maintained high proportions of cursor tracking throughout acquisition. All subjects demonstrated a postural tilt while moving the cursor from the mid-phase of acquisition through task mastery. In the isomorphic condition, all subjects tilted significantly more often in the direction of goal location than in the opposite direction. In three of the four series of tilting that were scored for subjects in the inverted condition, tilting occurred significantly more often toward the direction of goal location than the direction of required hand movement. Together these findings suggest that body tilting participates in the organization of directional movement of the cursor rather than reflecting merely the motoric requirements of the task (to manipulate a joystick).

Animals↗