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At least 811 records · Page 45Linked to original sources

PubMed1998

[A remote access system for inquiry of centrally stored data on patients suspected of malignant hyperthermia . A prototypical development for the Internet].

OBJECTIVES: Malignant hyperthermia (MH) is an inherited, potentially life-threatening syndrome of the skeletal muscles. It is a life-threatening complication of anaesthesia with a high mortality (8-10%). The risk of the patient during anaesthesia due to an overlooked predisposition for MH can be reduced by organisational measures, such as, all data of MH-susceptible patients and their families known in Germany must be brought together in a central register, MH-relevant data of patients must be readily retrievable, optional oral advice for those making an inquiry must be available. METHODS: To achieve this goal, a client-server system has been implemented: Standard Multimedia personal computers installed at the user's (anaesthetist's) site, linked to the Internet, will act as clients. On a server, relevant data of patients concerning MH-susceptibility are integrated in a central database. The newly developed software of this project ensures the legally prescribed data security on the server and the data routes. At the client's site, standard software together with automatically installed programmes from the server using Java applets ensure easy use and maintenance. IMPLEMENTATION: The total system was implemented and tested. Its functionality and high availability was demonstrated during this test period. Relevant aspects of data security were successfully examined by the data security officer of the University Hospitals of Baden-Württemberg. The user can optionally call a multifunctional teleconference which secures on-line advice if needed. This system demonstrates a safe and quick retrieval of MH relevant data of patients via Internet while at the same time guaranteeing all aspects of data protection and security. CONCLUSION: A prototypical database access system is described. It ensures safe access to patient data via Internet, while guaranteeing all aspects of data security.

Computer Communication Networks↗

PubMed1992

[The computer-assisted processing of CT data in planning endosseous implantation interventions].

The success of dental implantologic measures depends considerably on the correct positioning of the endosseous implants. A sufficient amount of bony substance is mandatory to provide overall covering of the implant with at least 1 mm of cortical bone. By the aid of a custom-developed software system, computed tomography image data can be handled on a conventional MS-DOS personal computer. The user is enabled to simulate size and positioning of the implant by interactive graphic animation. Quick and exact presentation is achieved by optimizing the computation algorithms. Storage needs are minimized by a segmentation procedure and additional compression of the image. Integrated patient data management and user friendly self-documenting program surfaces provide easy application.

Computer Graphics↗

PubMed1992

[Magnetic resonance tomography as the basis for biomechanical analysis. The simulation of the birth process as an example of the expanded information potentials of segmental imaging procedures].

A method is presented that enables the use of (static) informations from magnetic resonance imaging (MRI) for (dynamic) biomechanical analysis. Using a specially developed software MRI pixel matrices are colour-coded and--according to the principle of same density--line data are created. After sectional attribution of the resulting polygons a three-dimensional mesh of so-called finite elements is created which can then be used in deformation analysis. This method is exemplified by a project dealing with the simulation of birth mechanics, which is finally aimed at validating the results from radiologic pelvimetry. First analyses show that even under foetal head moulding conditions, being considered as normal, such sensitive structures as the cerebellum, brain stem as well as the ventricles with the plexus chorioidei are to be found within the maximum isobars within a range of 104-140 N(10.6-14.3 kp).

Adult↗

PubMed1998

[Topography-assisted correction of superficial irregularities of the cornea with the excimer laser].

BACKGROUND: A retinal image performance distorted by an asymmetric or irregular corneal surface cannot be compensated for with spherocylindric glasses completely. The best-corrected visual acuity is markedly decreased and contact lens fitting often impossible. The purpose of this study was to calculate the differential height between corneal topography raw data and any regular surface with mathematical methods in order to ablate the differential height with a computer-controlled laser beam, thereafter. METHODS: A Zernike decomposition of radial degree n = 16 was realized within a clinically relevant central corneal area of 8 mm in diameter based on corneal topography raw height data of a commercially available topographer (TMS-1, Tomey, Erlangen). Any target surface could be defined by varying weighting of the Zernike coefficients. The calculated differential height ablation between the raw data and the target surface given in a polar grid was transformed to a Cartesian grid to evaluate the sleeping time at each grid position considering the characteristic ablation curve for the intended ablation of the height difference. Subsequently, differential height ablation was simulated using an automated laser beam control for a modified excimer laser (MEL60, Aesculap-Meditec, Jena). We developed software tools for Zernike decomposition of corneal topography raw height data and time-regulated automatic laser beam control of the grid positions in the higher programming language C (Borland C++ 3.1, Borland Inc., München). RESULTS: Definition of a target surface can be realized alternatively by selecting a set of Zernike coefficients or defining a spherical or spherocylindrical surface by superposition of parabolic terms in a fixed proportion creating a best-fit target surface to the raw data. In originally "relatively flat" areas, the differential height profile indicates a "relatively deep" ablation resulting in relative steepening towards the periphery of the ablation zone. The resolution of the mechanical unit of the laser beam control consisting of two linear stepping motors is 9 microns in the focal plane with a reproducibility of 5 microns. The software unit is guiding the laser beam in a meandering fashion within the ablation area considering the calculated sleeping time for each grid position. Mean overlap of the 1 mm laser spots is 70%. The laser beam diameter of 1 mm effects a peripheral transition zone of 0.5 mm. CONCLUSIONS: Zernike decomposition of corneal topography height data is an efficient tool for localizing and quantifying superficial irregularities and for directly calculating an ablation profile from created differential height data. With an automatic laser beam control a well-defined laser ablation of superficial corneal irregularities is possible, subsequently.

Astigmatism↗

PubMedDate not supplied

[Fundus-oriented perimetry. Evaluation of a new visual field examination method for detecting angioscotoma].

BACKGROUND: Conventional automated perimeters usually work with a given set of grids and thus are normally not adapted to individual conditions. This fact restricts efficiency of this method not only for any single examination but also for follow-up studies. MATERIALS AND METHODS: A new method (patent pending) is introduced which superimposes an individual perimetric grid--corrected in respect to orientation, position and size--onto a patient's fundus image. A recently developed software realizes this procedure in a comfortable manner: the digitized fundus image is loaded into the computer by e.g. photo-CD or disc, depicted on a control monitor and mirrored if necessary. Assuming a central fixation, the foveola is translationally shifted to the center of the perimetric grid by the help of a crosshair. The blind spot which has been previously determined with kinetic perimetry is then superimposed onto the optic disc of the fundus image using a rotation and zoom function. In this way, it is possible to adapt the perimetric grid directly to the underlying individual fundus findings: thus, stimuli can be spatially concentrated or more frequently tested in special regions of interest. Additionally, test points can be dragged away from delicate positions to avoid artifacts. Examinations were carried out on a high resolution colour VDU of the Tübingen Electronic Campimeter (TCC). Alternatively, suited bowl perimeters can be used. RESULTS: In order to test the precision of the superimposing procedure, fundus oriented perimetry was performed to detect angioscotomata in 13 ophthalmologically normal subjects. Using dark stimuli (12'), visual field defects in the expected region, caused by retinal vessels, could be detected in 7 cases (= 54%). The resulting attenuation of differential light sensitivity in this circumscribed region was up to 12 dB. CONCLUSIONS: By means of a morphologically adapted, individual arrangement of stimulus locations fundus-oriented perimetry enables detection of even minute (angio-) scotomata.

Adult↗

PubMedDate not supplied

[Assurance and proof of satisfactory and complete information].

To prevent unjustified blame and claims enforced by patients, is necessary to prove evidence of an indisputable and complete preoperative information. With the help of our developed software it takes little effort to satisfy the given demands.

Female↗

PubMed1998

Interactive image guided surgery of the pineal region.

A wide variety of lesions occur in the pineal region. Of these, only 25% may benefit from surgical resection, being benign or radioresistant in nature. In the remaining 75% (malignant or radiosensitive), a conservative approach is preferred. Surgical resection of lesions arising from the pineal region has been associated with high morbidity and mortality, due to the complex microanatomy of this area. Recently computer-assisted surgery has emerged as an ideal method to safely approach many intracranial lesions. In the present study we discuss our experience in interactive image-guided surgical management of pineal mass lesions, in terms of patient selection, methodology, and surgical morbidity and mortality. From July 1992 to December 1996, 15 patients underwent interactive image guided surgical procedures. There were eight men and seven women. Age ranged from 5 to 79 years (mean 30). Preoperatively all patients underwent neuroimaging studies that included computed tomography and magnetic resonance imaging under stereotactic conditions. Surgical planning was carried out using the Neurological Surgical Planning System software developed at Wayne State University. In patients with a preoperative diagnosis of a malignant or radiosensitive lesion (n = 10), an interactive image-guided stereotactic biopsy was considered, whereas for those with benign or radioresistant lesions (n = 5) surgical excision using an infrared based system was carried out. Histological diagnosis was obtained in all patients. There was no morbidity and mortality associated with computer-assisted procedures for biopsies the diagnostic yield was 100%. For patients that underwent interactive image-guided surgery, gross total removal was accomplished in 3 and in 1 patient a subtotal resection greater than 90% was achieved. Interactive image-guided biopsy represents a safe and accurate method in the diagnosis of malignant and/or radiosensitive pineal lesions. Using this technique surgeons can simulate preoperatively the surgical trajectory, thus avoiding damage to critical and vascular structures. For patients with benign or radioresistant lesions, computer-assisted surgical excision is recommended.

Adolescent↗

PubMed2005

Prescription for the design and selection of density functional approximations: more constraint satisfaction with fewer fits.

We present the case for the nonempirical construction of density functional approximations for the exchange-correlation energy by the traditional method of "constraint satisfaction" without fitting to data sets, and present evidence that this approach has been successful on the first three rungs of "Jacob's ladder" of density functional approximations [local spin-density approximation (LSD), generalized gradient approximation (GGA), and meta-GGA]. We expect that this approach will also prove successful on the fourth and fifth rungs (hyper-GGA or hybrid and generalized random-phase approximation). In particular, we argue for the theoretical and practical importance of recovering the correct uniform density limit, which many semiempirical functionals fail to do. Among the beyond-LSD functionals now available to users, we recommend the nonempirical Perdew-Burke-Ernzerhof (PBE) GGA and the nonempirical Tao-Perdew-Staroverov-Scuseria (TPSS) meta-GGA, and their one-parameter hybrids with exact exchange. TPSS improvement over PBE is dramatic for atomization energies of molecules and surface energies of solids, and small or moderate for other properties. TPSS is now or soon will be available in standard codes such as GAUSSIAN, TURBOMOLE, NWCHEM, ADF, WIEN, VASP, etc. We also discuss old and new ideas to eliminate the self-interaction error that plagues the functionals on the first three rungs of the ladder, bring up other related issues, and close with a list of "do's and don't's" for software developers and users.

Journal Article↗

PubMed1996

Dual-energy X-ray absorptiometry for the measurement of gross body composition in rats.

Dual-energy X-ray absorptiometry (DXA) is a novel, non-invasive technique for the measurement of gross body composition in small animals. In the present study the absolute accuracy of the Hologic QDR-1000W scanner was assessed by comparison with direct analysis in twelve rats with a range of body fat and bone mineral content (BMC) values. Fat masses measured by DXA and petroleum-ether extraction were significantly different (P < 0.0023). The DXA technique consistently overestimated fat mass by approximately one third of the measured fat content. BMC derived from the measurement of Ca in ash gave a mean of 8.26 (range 1.57-15.71)g. BMC measured by DXA was not significantly different for the group as a whole. However, there was a trend for DXA to overestimate BMC in animals with low BMC and underestimate in those with higher BMC, compared with direct analysis, such that the 95% limits of agreement for the two techniques were +2.73 to -2.58 g. These results suggest that the present small-animal software developed for use with currently available Hologic machines does not give an accurate measure of gross body composition compared with the results from classical direct analysis.

Absorptiometry, Photon↗

PubMed2004

A new CT method for measuring cup orientation after total hip arthroplasty: a study of 10 patients.

BACKGROUND: It is difficult to assess the orientation of the acetabular component on routine radiographs. We present a method for determining the spatial orientation of the acetabular component after total hip arthroplasty (THA) using computed tomography. PATIENTS AND METHODS: Two CT-scans, 10 min apart, were obtained from each of 10 patients after THA. Using locally developed software, two independent examiners measured the orientation of the acetabular component in relation to the pelvis. The measurements were repeated after one week. To be independent of the patient position during scanning, the method involved two steps. Firstly, a 3D volumetric image of the pelvis was brought into a standard pelvic orientation, then the orientation of the acetabular component was measured. The orientation of the acetabular component was expressed as operative anteversion and inclination relative to an internal pelvic reference coordinate system. To evaluate precision, we compared measurements across pairs of CT volumes between observers and trials. RESULTS: Mean absolute interobserver angle error was 2.3 degrees for anteversion (range 0-6.6 degrees), and 1.1 degrees for inclination (range 0-4.6 degrees). For interobserver measurements, the precision, defined as one standard deviation, was 2.9 degrees for anteversion, and 1.5 degrees for inclination. A Student's t-test showed that the overall differences between the examiners, trials, and cases were not significant. Data were normally distributed and were not dependent on examiner or trial. INTERPRETATION: We conclude that the implant angles of the acetabular component in relation to the pelvis could be detected repeatedly using CT, independently of patient positioning.

Adult↗

PubMed1993

Audibility and identification of auditory alarms in the operating room and intensive care unit.

The audibility and the identification of 23 auditory alarms in the intensive care unit (ICU) and 26 auditory alarms in the operating rooms (ORs) of a 214-bed Canadian teaching hospital were investigated. Digital tape recordings of the alarms were made and analysed using masked-threshold software developed at the Université de Montréal. The digital recordings were also presented to the hospital personnel responsible for monitoring these alarms on an individual basis in order to determine how many of the alarms they would be able to identify when they heard them. Several of the alarms in both areas of the hospital could mask other alarms in the same area, and many of the alarms in the operating rooms could be masked by the sound of a surgical saw or a surgical drill. The staff in the OR (anaesthetists, anaesthesia residents, and OR technologists) were able to identify a mean of between 10 and 15 of the 26 alarms found in their operating theatres. The ICU nurses were able to identify a mean of between 9 and 14 of the 23 alarms found in their ICU. Alarm importance was positively correlated with the frequency of alarm identification in the case of the OR, rho = 0.411, but was not significantly correlated in the case of the ICU, rho = 0.155. This study demonstrates the poor design of auditory warning signals in hospitals and the need for standardization of alarms on medical equipment.

Adult↗

PubMed1998

A quality assurance network in Central European countries--radiotherapy infrastructure.

A survey of the infrastructure in radiotherapy centres in three Central European countries has been performed as a first step in the development of a quality assurance network. Data concerning radiotherapy equipment, staff and number of patients treated in most of the radiotherapy centres from Czech Republic, Poland and Hungary were collected at the beginning of 1994. Equipment data have shown that 35% of 182 treatment units are conventional x-ray units, 35% 60Co units, 19% linear accelerators, 7% 137Cs units and 4% betatrons. About 47% of high energy units are older than 12 years and about 20% older than 21 years. An important number of centres still have no simulator which would constitute an important handicap to carry out adequate radiotherapy. The number of treatment planning systems has also been registered; 44% being PC-based systems with locally developed software. Large variations are observed in the number of patients treated per year, per high energy unit, but 12/47 centres treat more than 700 patients per year and unit. On the average, staffing seems adequate in numbers though there are wide variations. The main limitation of radiotherapy infrastructure in the Central European countries is the low number of linear accelerators and simulators and the advanced age of therapy units.

Czech Republic↗

PubMed2004

Quantifying biofilm structure: facts and fiction.

There is no doubt among biofilm researchers that biofilm structure is important to many biofilm processes, such as the transport of nutrients to deeper layers of the biofilm. However, biofilm structure is an elusive term understood only qualitatively, and as such it cannot be directly correlated with any measurable parameters characterizing biofilm performance. To correlate biofilm structure with the parameters characterizing biofilm performance, such as the rate of nutrient transport within the space occupied by the biofilms, biofilm structure must first be quantified and expressed numerically on an appropriate scale. The task of extracting numerical parameters quantifying biofilm structure relies on using biofilm imaging and image analysis. Although defining parameters characterizing biofilm structure is relatively straightforward, and multiple parameters have been described in the computer science literature, interpreting the results of such analyses is not trivial. Existing computer software developed by several research groups, including ours, for the sole purpose of analyzing biofilm images helps quantify parameters from biofilm images but does nothing to help interpret the results of such analyses. Although computing structural parameters from biofilm images permits correlating biofilm structure with other biofilm processes, the meaning of the results is not obvious. The first step to understanding the quantification of biofilm structure, developing image analysis, methods to quantify information from biofilm images, has been made by several research groups. The next step is to explain the meaning of these analyses. This presentation explains the meaning of several parameters commonly used to characterize biofilm structure. It also reviews the authors' research and experience in quantifying biofilm structure and their attempts to quantitatively relate biofilm structure to fundamental biofilm processes.

Anti-Bacterial Agents↗

PubMed1993

DNA double-strand break induction in yeast by X-rays and alpha-particles measured by pulsed-field gel electrophoresis.

Pulsed-field gel electrophoresis was used to separate the chromosomes of the diploid yeast Saccharomyces cerevisiae 211*B after irradiation with X-rays and alpha-particles. After electrophoresis, gels were stained with ethidium bromide, placed on a UV-transilluminator and photographed with a digitizing camera connected to a personal computer. The pictures obtained were processed with the help of specially developed software which allows for the correction of the camera's shading effect and background fluorescence. Linearity between DNA amount and fluorescence was demonstrated. Fluorescence intensity for the band with the lowest electrophoretic mobility was found to decrease exponentially with dose. Based on the known size of the native DNA molecules, double-strand break yields could be calculated. These were found to be (8.2 +/- 0.4) and (14.8 +/- 0.5)10(-12) (g/mol)-1 Gy-1 for 80 keV X-rays and 3.5 MeV 241Am alpha-particles respectively which gives a relative biological effectiveness of 1.8 +/- 0.1.

Alpha Particles↗

PubMed2005

IT-driven patient safety at the heart of radiology service improvement.

Patient safety is a fundamental requirement of modern health-care systems and the application of information technology (IT) to this activity should have improvements in the area as one of its goals. Indeed, ensuring that the diagnostic IT strategy is optimized, for example, the use of IT in service redesign or data analysis, forms one of the main platforms for the National Framework for Service Improvement in Radiology. This paper presents both the concept behind and the results of a project that has been under way in the UK involving St Helens and Knowsley NHS Trust and IRS Ltd concerned with implementing effective IT-driven scientific support in the field of medical radiation protection. Locally developed software is employed in assessing, managing, and analysing patient dose data arising from X-ray examinations performed in the busy department of a large district general hospital (DGH). Such data are analysed in a variety of ways, for example, over time and according to location (department or X-ray room). This analysis not only provides a measure of performance against nationally agreed dose reference levels (DRLs) but also enables a detailed analysis of any variations as well as the establishment of local DRLs (performance indicators). This process provides quantitative input to management strategies aimed at service improvement. Such strategies are geared towards the support of the Ionizing Radiations (Medical Exposures) Regulations 2000 as well as implementation of quality-management principles at the heart of radiology practices.

Cooperative Behavior↗

PubMed1987

Collection and analysis of complex ELISA data using a microcomputer.

A system for automatic Enzyme-Linked Immunosorbent Assay (ELISA) data collection and processing is described. Hardware for the system consists of a Dynatech microplate reader and Apple II series microcomputer. Software developed by the authors allows automatic configuration of the reader and direct data input from the microplate reader to the microcomputer. After optical density data is input through the interface, it can be printed out as either optical density values, or as scaled values (from 0 to 9) in a color-coded matrix. Data can be stored and later recalled in either format, allowing several sets of data to be merged into one large, color-coded chart. Results from several different microplates can be combined and sorted in a single printout to expedite interpretation of data.

Computers↗

PubMed1994

A fast non-invasive beam check for mammography x-ray units.

A prototype instrument is presented for the indirect evaluation of the main physical parameters characterizing a mammographic x-ray beam. The instrument consists of an x-ray probe with four filtered solid-state detectors connected to a signal-conditioning electronic circuitry and a high-speed digitizer interfaced to a portable personal computer. The system, governed by an ad hoc developed software, can measure kVp, kV waveform, ripple, HVL, exposure time and exposure in a single shot of the x-ray beam with good accuracy. The system should prove very useful to any quality-control programme for mammography.

Equipment Design↗

PubMed2002

Effects of intra-fraction motion on IMRT dose delivery: statistical analysis and simulation.

There has been some concern that organ motion, especially intra-fraction organ motion due to breathing, can negate the potential merit of intensity-modulated radiotherapy (IMRT). We wanted to find out whether this concern is justified. Specifically, we wanted to investigate whether IMRT delivery techniques with moving parts, e.g., with a multileaf collimator (MLC), are particularly sensitive to organ motion due to the interplay between organ motion and leaf motion. We also wanted to know if, and by how much, fractionation of the treatment can reduce the effects. We performed a statistical analysis and calculated the expected dose values and dose variances for volume elements of organs that move during the delivery of the IMRT. We looked at the overall influence of organ motion during the course of a fractionated treatment. A linear-quadratic model was used to consider fractionation effects. Furthermore, we developed software to simulate motion effects for IMRT delivery with an MLC, with compensators, and with a scanning beam. For the simulation we assumed a sinusoidal motion in an isocentric plane. We found that the expected dose value is independent of the treatment technique. It is just a weighted average over the path of motion of the dose distribution without motion. If the treatment is delivered in several fractions, the distribution of the dose around the expected value is close to a Gaussian. For a typical treatment with 30 fractions, the standard deviation is generally within 1% of the expected value for MLC delivery if one assumes a typical motion amplitude of 5 mm (1 cm peak to peak). The standard deviation is generally even smaller for the compensator but bigger for scanning beam delivery. For the latter it can be reduced through multiple deliveries ('paintings') of the same field. In conclusion, the main effect of organ motion in IMRT is an averaging of the dose distribution without motion over the path of the motion. This is the same as for treatments with conventional beams. Additional effects that are specific to the IMRT delivery technique appear to be relatively small, except for the scanning beam.

Computer Simulation↗