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At least 1,279 records · Page 71Linked to original sources
PubMed2006

A possible quality control protocol for Doppler ultrasound for organizational time optimization.

Acceptance tests quantitatively determine equipment performance characteristics. Before a new probe is accepted, performance tests can be also used to compare performance of other probes. Routine performance tests verify device operational stability over the time. We developed an efficient and effective testing programme aiming to demonstrate changes in imaging performance relevant to clinical quantitative use of pulsed and colour Doppler. For each scanner-transducer tested, we introduced some quantitative and semi-quantitative parameters in relation to the clinical request for which the equipment was chosen. The proposed quantitative tests may also be used as qualitative tests, when it is suspected that scanner performance is deteriorating. The measurements, obtained with different units, differed also in the case of probes operating at the same depth and peak velocity. Without a quality control (QC) program, significant variations are likely to be reported when peak velocity of the same flow is measured with different instruments. Our experience suggests that modern digital equipments used in serial measurements may be stable over the time and that calibrated phantom may enable preventive identification of corrective action to units and probes. Manufacturers and independent laboratories applying a quality control protocol can increase our experience to recognize and deal with the involved problems.

Blood Flow Velocity↗
PubMed1996

[The direct antiglobulin and elution tests: evaluation of quality control in Blood Transfusion Centers].

The Société Française de Transfusion Sanguine and the Centre National de Référence pour les Groupes Sanguins performed a quality control to evaluate the performances of two serological tests: the Direct Antiglobulin Test (DAT) and the Elution test. Among the 110 Blood Transfusion Centers participating in this control, 80 (73%) returned a result. Of these, 68 results were correct for the DAT (85%; positive for type IgG) and 31 results were correct for the elution (39%; anti-FY1). This control gave the opportunity to confirm the main procedures used in routine testing on a national scale. The analysis of the results underlines the importance of the choice of a standardized technique for these tests. Such controls are useful to appreciate the quality of the routine tests and to find the means to improve them.

Blood Transfusion↗
PubMed1993

Establishment of National Quality Control Reference Panels and Requirements for Hepatitis B diagnosis reagents in China.

A National Quality Control Reference Panel for Hepatitis B Diagnostic Kits has been established. Markers for these standards which were prepared include National Standards for HBsAg and anti-HBs calibrated against WHO International Standards. In addition, Reference Panels for HBeAg, anti-HBe, anti-HBc, anti-HBc IgM and HBV were established and National Requirements set. These panels have been used for the nationwide evaluation of HB kits and for licensing purposes.

China↗
PubMed2003

The Asymptomatic Carotid Stenosis and Risk of Stroke (ACSRS) study. Aims and results of quality control.

AIM: The results of the Asymptomatic Carotid Atherosclerosis Study (ACAS) study have provided the first scientific evidence that in patients with asymptomatic carotid stenosis greater than 60% carotid endarterectomy reduces the risk of stroke from 2% to 1% per year. The implications are that approximately 20 operations need to be performed in order to prevent 1 stroke in 5 years. The aims of the Asymptomatic Carotid Stenosis and Risk of Stroke (ACSRS) study are to identify a subgroup or subgroups at a risk for stroke higher than 4% and a group at a risk for stroke less than 1% per year using systemic and local risk factors (plaque characterization) in addition to the degree of stenosis. The aim of this paper is to present the protocol and the results of the quality control. METHODS: The ACSRS is a multicentre natural history study of patients with asymptomatic internal carotid diameter stenosis greater than 50% in relation to the bulb. The degree of stenosis is graded using multiple established ultrasonic duplex criteria. In addition, ultrasonic plaque characterization is performed and clinical risk factors and medications are recorded. Training is provided centrally. All carotid ultrasound examinations are recorded on video-tape which together with CT-brain scans and ECG are analysed at the coordinating centre with feedback information to partner centres. RESULTS: The video recordings and analysis of data centrally with feed back information have provided quality control with a significant improvement not only in the completion of data forms but also in the grading of internal carotid stenosis and plaque recordings using ultrasound. CONCLUSION: The high level of quality of data collected will add credibility to the results of the ACSRS study and may eventually promote the development of international standards of plaque imaging and characterization.

Carotid Artery, Internal↗
PubMedDate not supplied

[Methodology for quality control of an ointment with antivaricose properties].

A personal formulation of an ointment with antivaricose properties is presented. A methodology for the physicochemical and rheologic control, including all parameters required by the standards for ointments quality control, was designed. The analyses showed that the ointment is stable in time, has a thixotropic consistency and behaviour and does not require special preservation conditions.

Chemical Phenomena↗
PubMed2002

Quality assurance and quality control programme in the Personal Dosimetry Department of the Greek Atomic Energy Commission.

A quality assurance (QA) and quality control (QC) programme was applied to the personal monitoring department (TLD based) of the Greek Atomic Energy Commission (GAEC). This programme was designed according to the recommendations of international bodies such as the International Organization for Standardization (ISO), the International Electrotechnical Commission (IEC), the International Atomic Energy Agency (IAEA) and the European Commission (CEC). This paper deals with the presentation of the QA/QC programme which includes administrative data and information, technical checking of the equipment, acceptance tests of new equipment and dosemeters, issuing and processing of the dosemeters, dose evaluation, record keeping and reporting, traceability and reproducibility, handling of complaints, internal reviews and external audits.

Calibration↗
PubMed1981

Results of the Italian interlaboratory quality control program for estradiol receptor assay.

This article presents results of the first Italian quality control program for determining the estradiol receptor on lypophilized guinea pig and calf uteri. Despite considerable variability in quantitative terms, the results concur in ability to define samples as positive or negative for receptor content. One of the parameters that most strongly influences accuracy of determination of receptor concentration is protein assay. The evaluation of several lyophilized preparations at scalar concentrations permitted identification, by linear regression, for each laboratory of the systematic and non-systematic variables. More comparable results will be forthcoming when a standardized methodology program has been fully adopted.

Animals↗
PubMed1999

Statistical quality control in clinical trials.

We propose to apply statistical methods of industrial process and quality control to accumulating data in a statistical monitoring center of a clinical trial. We discuss some specific issues connected with the application of these methods over calendar time to patients' characteristics (at a particular individual patient time) or to more formal monitoring characteristics (like the number of queries per case record form). The tools used are Shewart charts, plots, breakpoint regression, and recursive residuals with cusums and V-charts, applied to measurement and event data. A software program based on SAS macros allows easy application of the methods. Some examples, with graphical outputs, from an ongoing trial on patients with primary malignant melanoma, illustrate the methods.

Cholesterol↗
PubMed1991

[Improving the quality control of health care].

The problem of raising the quality and effectiveness of medical care in the agricultural region of the country is being considered from the point of view of systems approach where a priority is given to the formation of a common modern scientific technology of delivering medical care different from feldsher-midwifery units to specialized centres. Three years period of introducing the system of improving the management of quality and effectiveness of medical care delivery resulted in reduction of morbidity associated with temporary and persistent disability from respiratory diseases, reduction of mortality from circulatory diseases in working age population.

Adolescent↗
PubMed1997

Effect of analytical run length on quality-control (QC) performance and the QC planning process.

The performance measure traditionally used in the quality-control (QC) planning process is the probability of rejecting an analytical run when an out-of-control error condition exists. A shortcoming of this performance measure is that it doesn't allow comparison of QC strategies that define analytical runs differently. Accommodating different analytical run definitions is straightforward if QC performance is measured in terms of the average number of patient samples to error detection, or the average number of patient samples containing an analytical error that exceeds total allowable error. By using these performance measures to investigate the impact of different analytical run definitions on QC performance demonstrates that during routine QC monitoring, the length of the interval between QC tests can have a major influence on the expected number of unacceptable results produced during the existence of an out-of-control error condition.

Chemistry, Clinical↗
PubMedDate not supplied

External quality control program of four blood cell counters.

OBJECTIVE: To evaluate an internal-external quality control program of four automated counters. METHODS: Every one or two weeks during 14 months, six direct cell parameters were measured in three fresh blood samples in four Coulter counters. The median per parameter of the working day was used to detect inaccuracies and if the participants' internal control program confirmed it, a recalibration of the parameter was performed. RESULTS: In 21 of 22 instances, the internal program confirmed an inaccuracy and a recalibration was done (4 leukocyte and 5 erythrocyte counts, 5 hemoglobins, 7 red-cell volumes). In these four parameters there were no large differences between the lowest and highest counter upon analyzing all results whereas all counters differed from one another in the parameters that cannot be recalibrated by the user (platelet volume, red-cell distribution width). CONCLUSIONS: 1. The program contributed to good accuracy and precision within-counters and good concordancy between-counters in the parameters that can be recalibrated. 2. The counter differences in red-cell distribution width were sufficiently large (up to 9%) to affect clinical interpretation. This poses the need of width distribution reference ranges for each counter.

Blood Cell Count↗
PubMed1999

Quality control in a manual and an automated leukocyte differential count.

Quality control (QC) has been introduced in laboratories, and QC surveys in leukocyte differential count to enhance quality have been performed by College of American Pathologists, Japanese Association of Medical Technologists, Osaka Medical Association and manufacturers. The results of QC survey in a manual leukocyte differential count indicated problems on the differentiation of segmented neutrophils and band neutrophils and the detection of pathological blood cells on blood smear. While the results of QC survey in an automated leukocyte differential count performed by same manufacturer with an automated blood cell counter were satisfactory, however, there was a difference in leukocyte differential cell counts among laboratories with other manufacturer's instruments because the synthetic blood material used in QC is an exclusive item for an instrument. It is necessary to further reeducate the medical technologists in order to improve morphological performance, and to standardize the synthetic blood material for compatibility with various automated blood cell counters.

Automation↗
PubMed1989

Development of a meropenem susceptibility disc: drug content, preliminary interpretive and quality control criteria and potency bioassay.

Laboratory studies were conducted to develop an appropriate susceptibility disc for meropenem. Laboratory-prepared paper discs containing 5, 10, and 20 micrograms of meropenem were investigated. Agar dilution MICs and agar disc diffusion tests were performed with 367 rapidly growing clinical isolates by methods recommended by the National Committee for Clinical Laboratory Standards (NCCLS). Agar disc diffusion tests with 10 micrograms meropenem discs acceptably defined organisms as susceptible or resistant. The preliminary interpretive zone size criteria for 10 micrograms meropenem discs were: susceptible, greater than or equal to 14 mm, and resistant, less than or equal to 10 mm, by application of the NCCLS imipenem MIC interpretive susceptible and resistant breakpoints to the meropenem data. A total of 270 agar disc diffusion assays were performed with each of four ATCC reference strains, using prototype discs (Becton Dickinson (BBL] containing 10 micrograms meropenem. The preliminary quality control limits for agar disc diffusion tests with these discs are: Escherichia coli ATCC 25922, 28-32 mm; Pseudomonas aeruginosa ATCC 27853, 26-31 mm; Staphylococcus aureus ATCC 25923, 33-39 mm; and Enterococcus faecalis ATCC 29212, 19-23 mm. Further studies are necessary to re-evaluate both the preliminary interpretive and quality control criteria before definitive limits can be established. A reproducible, large plate bioassay with Enterococcus faecalis ATCC 29212 was developed to monitor meropenem disc potency.

Bacteria↗
PubMedDate not supplied

External quality control survey for alpha-fetoprotein assay.

Starting from 1984 we organized an interlaboratory quality control (QC) survey for the tumor marker AFP in which 100-150 laboratories have been involved. Seven consecutive QC cycles have been carried out during the period 1984-1988; 15-20 samples have been prepared and sent in each cycle. The 11 kits more used in the survey, which use three different immunological methods (3 kits EIA, 3 kits RIA, and 5 kits IRMA) were evaluated. Since the results of AFP assays were expressed as ng/ml of different local standards of the various kits, the participants were asked to convert their results in UI/ml of the 1st IRP 72/225 distributed by WHO. The total variability of AFP assay resulted approximately constant (19.9-24.7 CV%) during the all QC period. The validity of the consensus mean of AFP determinations obtained in the survey and assumed as reference value has been checked by recovery experiments. Regression analysis indicates that the consensus means found in these samples are in very good agreement with the added AFP. The analytical performance achieved by the most popular methods/kits, observed in the last period, are also reported.

Italy↗
PubMed2001

Standardization of broth microdilution and disk diffusion susceptibility tests for Actinobacillus pleuropneumoniae and Haemophilus somnus: quality control standards for ceftiofur, enrofloxacin, florfenicol, gentamicin, penicillin, tetracycline, tilmicosin, and trimethoprim-sulfamethoxazole.

Quality control (QC) standards for the in vitro antimicrobial susceptibility testing of two fastidious veterinary pathogens, Actinobacillus pleuropneumoniae and Haemophilus somnus, were developed in a multilaboratory study according to procedures established by the National Committee for Clinical Laboratory Standards for broth microdilution and disk diffusion testing. The medium recommended for the broth microdilution testing is cation-adjusted Mueller-Hinton broth supplemented with 2% lysed horse blood, 2% yeast extract, and 2% supplement C. This medium has been designated veterinary fastidious medium. The medium recommended for the disk diffusion testing is chocolate Mueller-Hinton agar. The recommended QC organisms are A. pleuropneumoniae ATCC 27090 and H. somnus ATCC 700025. The QC MICs of ceftiofur, enrofloxacin, florfenicol, gentamicin, penicillin, tetracycline, tilmicosin, and trimethoprim-sulfamethoxazole were determined for each isolate, as were the zone size ranges. Of the results from the participating laboratories, 94.0% of the zone diameter results and 97.0% of the MIC results fell within the suggested QC ranges for all compounds. These QC guidelines should allow greater accuracy in interpreting results when testing these antimicrobial agents against fastidious pathogens.

Actinobacillus Infections↗
PubMed1992

[Swiss quality control in bacteriology and mycology 1989-1991].

Since 1983 there has been a voluntary quality assessment scheme (QAS) for bacteriology and mycology laboratories in Switzerland directed by the Committee for Quality Control of the Swiss Society for Microbiology. For the first time, the results of this QAS for the period between 1989 and 1991 are made available to a wider public. During the period in question, a steadily increasing number of participants received three samples containing microorganisms four times a year for identification and susceptibility testing. A mean percentage value of a point rating, with a maximum of 12 points, was calculated every year for each laboratory. Values of < or = 75% were defined as insufficient. For a first evaluation, laboratories were assigned to the categories of cantonal (and university) laboratories (C/U), private laboratories (P), and hospital laboratories (H, in hospitals which are neither university nor other tertiary care centres). Significant differences were detected between C/U and P on the one hand and H on the other. As a rule, H obtained poorer results than the two categories, examined fewer specimens, and their percentage with results < or = 75% was significantly higher. The second evaluation classified laboratories according to their recognition by the Swiss Federal Department of Public Health (FDPH). For statistical reasons, H had to be grouped with C/U. Nevertheless, their share of non-recognized laboratories was exceedingly high (15 out of 17 participants in 1991). Recognized laboratories constantly showed a better performance than non-recognized laboratories, examined more specimens, and their number of laboratories obtaining results < or = 75% was much lower.(ABSTRACT TRUNCATED AT 250 WORDS)

Accreditation↗
PubMed1993

ARIC hemostasis study--III. Quality control. Atherosclerosis Risk in Communities.

Methods and results from the quality assurance program of the Atherosclerosis Risk in Communities (ARIC) Study regarding hemostasis variables are presented, following up previous reports in this journal on standardized procedures for blood collection and processing (7) and an organized plan for the performance of those procedures (8). Efforts were made to control for and assess all sources of variability, from venipuncture to laboratory analysis, including also local field center processing and sample shipping. The quality control program included (a) a standardized protocol for blood collection and processing; (b) training, certification, and annual recertification of field center personnel for blood collection and processing; (c) monitoring of fasting times, phlebotomy times, processing times, and shipping problems; (d) hemostatic laboratory internal quality control; (e) a replicate blood sample program; (f) an intraindividual variability study; and (g) continual monitoring of quality control and study participants' data. This paper focused on items (c), (d), and (e). Measures of variation, generally standard deviations and coefficients of variation, are estimated for replicate blood sampling and internal quality control data, for activated partial thromboplastin time, fibrinogen, factor VII and VIII activity, von Willebrand factor, antithrombin-III, and protein C. The results demonstrate that it is possible to reliably measure these hemostatic variables in a large multicenter study.

Arteriosclerosis↗
PubMed2001

A computerised quality control testing system for B-mode ultrasound.

Current methods of ultrasound (US) imaging quality control involve an observer taking a series of measurements on test object images. This process is very labour-intensive, rapidly becoming more so as the complexity of US scanners increases. Also, many of the measurements are based on the subjective judgement of the operator and are, therefore, prone to an undesirable level of intraobserver and interobserver variation. We have developed a suite of programs to analyse captured US images to estimate a number of performance parameters, including resolution, high- and low-contrast penetration depths and high- and low-contrast sensitivity. In this system, images of the ATS Laboratories Multipurpose Phantom Model 539 are acquired on a PC with a video capture card, and analysed using the software developed. Automated tests have been developed for resolution, low- and high-contrast penetration and low- and high-contrast sensitivity. A preliminary validation of the system was carried out using images from two curvilinear probes and a linear-array probe operating at 5 MHz, 7.5 MHz and 10 MHz, respectively. The 95% confidence intervals ranged from +/- 17% to +/- 21% for resolution measurements and from 0% to +/- 1.5% for low-contrast penetration. The system provides an index of visibility for high- and low-contrast targets, as compared to the coarse visual assessment of a human observer, with 95% confidence intervals ranging from +/- 6% to +/- 13% for low-contrast sensitivity and from +/- 3% to +/- 25% for high-contrast sensitivity. Advantages of the system over the human observer include improved reproducibility and increased information regarding visibility of targets. A more detailed multicentre validation is currently being undertaken.

Automation↗