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At least 343 records · Page 19Linked to original sources
PubMed1989

New datum handling methods for the quality control of antibiotic solutions and plates used in the antimicrobial susceptibility test.

Quality control programs are described for monitoring both the antibiotic solutions and the plates used in the dilution antimicrobial susceptibility test. For the quality control of antibiotic solutions, a simple comparative disk diffusion assay is used in which the data are expressed as zone ratios calculated from the following formula: zone ratios = mean zones of inhibition for disks impregnated with antibiotic under test/mean zones of inhibition of previously prepared quality control disks impregnated with the same antibiotic. The rejection limits set for this method are twice as stringent as for MIC estimation, and its precision is four times greater. For quality control of the antibiotic agar plates, fluid was absorbed directly into filter paper disks placed on the surface of the medium. These disks were then transferred to a seeded plate to produce zones of inhibition. These zones of inhibition were then converted to zone ratios by dividing the zone of inhibition for the individual antibiotics by the mean of the total zones of inhibition for all the antibiotics tested on the same plate. We further normalized these data by expressing each entry as a standard normal deviate calculated from the mean and standard deviation of the cumulative data for each individual antibiotic. The use of zone ratios reduced batch-to-batch variation, and standard normal deviate values gave a uniform result for convenience. The method has a sensitivity equal to that of an MIC estimation if it were possible to estimate the MICs of antibiotics at these low levels.

Anti-Bacterial Agents↗
PubMedDate not supplied

Lyophilized and natural urine specimens in the quality control of analyses of toxic metals.

A quality control program of analyses of toxic metals in urine has been carried out in the Nordic countries since 1978. In connection with these programs, the advantages and disadvantages of lyophilized compared to natural urine specimens as control materials have been investigated in three successive similar studies. Three parallel lyophilized and natural specimens were distributed to 12 participating laboratories. Two of the three specimen pools were spiked with known amounts of As, Cd, Cr, Hg, Ni, and Pb standard solutions. The data indicate no clear differences in the mean concentrations, coefficients of variation, or mean recoveries for the various metals between the two control materials used with the various types of analytes. However, rather wide random variations were observed, emphasizing the analytical difficulty of these analyses and the need for routine quality control.

Freeze Drying↗
PubMed1991

[Quality control in autologous blood donation and transfusion].

In Germany the quality control for homologous blood preparations is well-established. On the other hand, the quality assurance for autologous blood products is much more complicated, due to more problems concerning blood collection and preparation. Therefore, quality control is even more strongly indicated in autologous hemotherapy. On the basis of existing standards for the preparation of homologous blood components, we defined guidelines for the quality control of the autologous preoperative blood deposit, plasmapheresis, acute normovolemic hemodilutions and the intraoperative autotransfusions. We took into account that particularly the perioperative techniques only allow the collection of blood components with a reduced quality. The guidelines include the recommendation of adequate schooling for the staff.

Blood Cell Count↗
PubMed1997

Defining the best quality-control systems by design and inspection.

Not all of the many approaches to quality control are equally effective. Nonconformities in laboratory testing are caused basically by excessive process variation and mistakes. Statistical quality control can effectively control process variation, but it cannot detect or prevent most mistakes. Because mistakes or blunders are frequently the dominant source of nonconformities, we conclude that statistical quality control by itself is not effective. I explore the 100% inspection methods essential for controlling mistakes. Unlike the inspection techniques that Deming described as ineffective, the new "source" inspection methods can detect mistakes and enable corrections before nonconformities are generated, achieving the highest degree of quality at a fraction of the cost of traditional methods. Key relationships between task complexity and nonconformity rates are also described, along with cultural changes that are essential for implementing the best quality-control practices.

Chemistry, Clinical↗
PubMed1984

Dose and quality control (DQC) in diagnostic radiology.

Dose and quality control in diagnostic radiology can play an important role in reducing x-ray exposure and costs whilst maintaining a high level of imaging quality and diagnostic benefit. It can also become very costly. Current government regulations demand unnecessary accuracy in the measurement and performance of certain parameters of x-ray generators whilst ignoring others which are more important. They totally neglect imaging systems. We urge a more critical approach to the requirements for dose and quality control programs. We propose the exchange of information through a user's club and a less regulatory but equally important role for government.

Calibration↗
PubMed2003

Compensator quality control with an amorphous silicon EPID.

The calibration and quality control of compensators is conventionally performed with an ion chamber in a water-equivalent phantom. In our center, the compensator factor and four off-axis fluence ratios are measured to verify the central axis beam modulation and orientation of the compensator. Here we report the investigation of an alternative technique for compensator quality control using an amorphous silicon electronic portal imaging device (a-Si EPID). Preliminary experiments were performed to identify appropriate EPID operating parameters for this relative dosimetric study and also to quantify EPID operation. The pixel value versus energy fluence response of the EPID for both open and compensated fields was then determined, and expressed via calibration curves. For open fields the response was seen to be linear, whereas for compensated fields it exhibited a small quadratic component. To account for field size effects, we measured EPID scatter factors. These exhibited small but non-negligible dependencies on compensator thickness and source-detector distance. Finally, a number of test and clinical compensators were evaluated to assess the suitability of the EPID for compensator quality control. Our results indicate that the a-Si EPID can measure clinical compensator factors and off-axis energy fluence ratios to within 2% of values measured by a Farmer chamber on average, and so is a suitable ion chamber replacement.

Calibration↗
PubMed2003

[Cause and measure of short of quality control on Chinese medicine herbs].

Chinese medicine is short of quality control for three reasons. Firstly, near 90 percent Chinese medicine herbs are lack of quality standards and hard to be evaluated. Secondly, basal study falls behind relatively, which limites development speed of quality control and quality standard. Finally, Chinese medicine herbs haven't uniform refine operating norm. We must strengthen basal study, constitute the inspection norm of Chinese medicine herbs quality and establish perfect technical supervise system as fast as possible.

Animals↗
PubMed2005

Quality control of B-mode ultrasonic measurement of carotid artery intima-media thickness: the European Lacidipine Study on Atherosclerosis.

BACKGROUND: The European Lacidipine Study of Atherosclerosis (ELSA) was a prospective, randomized, double-blind, multinational interventional trial using B-mode ultrasound measurement of carotid intima-media thickness (IMT) in 2259 hypertensive individuals. ELSA showed that 4-year treatment with the calcium antagonist, lacidipine, significantly slowed down progression of carotid atherosclerosis as compared with treatment with the beta-blocker, atenolol. OBJECTIVE: To report data on cross-sectional and longitudinal quality control of the ultrasound measurements implemented throughout ELSA. METHODS: Patients underwent scans at baseline and at each annual visit. All endpoints were measured while the study was in progress (initial measurements). In addition to the cross-sectional quality control procedures, a longitudinal quality control procedure of re-reading 250 baseline scans at yearly intervals was implemented, to control possible reader drift. After the study had been completed, the primary endpoint was measured again under the same condition of cross-sectional quality control. RESULTS: Cross-sectional quality control data showed high reliability for all endpoints at all time points except for single maximum IMT (Tmax) and internal carotid IMT. Within-reader reliability was constantly better than between-reader reliability but, for the primary endpoint, between-reader reliability remained excellent. Initial and longitudinal quality control measurements showed a time trend toward lower IMT values. After application of a correction factor calculated from longitudinal quality control, all initial measurements no longer decreased with time, and the corrected IMT measurements were reasonably similar to those made after completion of the study. CONCLUSION: For long-term epidemiological studies and clinical trials, both cross-sectional and longitudinal quality control are critical to the reliability of measurements. In order to evaluate the absolute change in IMT and interpret study results without bias, both must be implemented.

Carotid Arteries↗
PubMed1989

Quality control of medical practice in Bophuthatswana.

Quality control of medical care in hospitals is an already established monitoring procedure in the United States, enacted by the American Congress as a Public Law. It was adopted and adapted by other Western countries to fulfill its major aim of improving the quality of patient care in hospitals. The various methodologies used so far serve other important purposes as well, i.e., as an education process, a reporting mechanism and to contain the ever increasing costs of medical services. The underlying concept is the legal recognition that the hospital in society exists under "a contract" that requires it to exercise reasonable diligence regarding the quality of medical care to all patients at all times. This concept applies to Bophuthatswana as well. It does so, because one of our major goals is to provide health services to all, as declared by the WHO and UNICEF; and that this goal encompasses many basic human rights which are already in the process of realization. High-quality medical and patient care are two components of this set of rights. However, social priorities here are different from those in developed societies because of socio-economic constraints. Thus, our health policy is unique--primary health care which is hospital-based and community-oriented with the nursing sector at its core. Therefore, our quality control system will be also a unique one and will fit into the specific structure and needs of the health care system and its high ethical approach.

Africa, Southern↗
PubMedDate not supplied

Frozen section diagnosis: a quality control study.

In a quality control study we reviewed six hundred and eighty one frozen section specimens sent to our department from 1981 to 1989. Accuracy was 98%. Diagnosis was deferred in 1%. False positive diagnosis for malignancy was made in one (0.15%) case and false negative diagnosis for malignancy in thirteen (2%) cases. Most of the inaccurate diagnoses concerned the female breast and the omentum. Incorrect diagnoses were due to interpretation of the pathologic findings (50%), to microscopic sampling (36%) and to gross sampling (14%). Some of the lesions are difficult to diagnose even in permanent sections. Technical skill and diagnostic expertise are essential for high diagnostic accuracy in the method of frozen section.

False Negative Reactions↗
PubMed1984

Internal quality control of radioimmunoassays.

A quality control system for radioimmunoassays is described. The system is designed to give a high probability for error detection and a low probability for false rejection by use of a combination of three control samples with different ligand concentration levels. Intra-assay precision profile is also calculated on the basis of deviations between the sample and the standard duplicates.

Circadian Rhythm↗
PubMed1998

Quality control and factor VIII assays.

Quality assurance is a vital prerequisite of good laboratory practice. The application and continuous scrutiny of adequate internal quality control measures are essential to ensure that laboratory performance is consistent from day to day. External quality assessment is particularly important to verify the accuracy and reliability of laboratory results Consequently, without appropriate IQC and EQA, laboratory results can have no true validity.

Biological Assay↗
PubMed1996

[Quality control after pelvic injuries with a scoring system].

Quality control after treatment of pelvic injuries is often poor because many criteria of assessment lack objectivity. In order to attain improved comparability of results, we present a scoring system including subjective as well as functional and radiological criteria. The assessment is based on a calculation according to the importance of the criteria. The total score supplies the final result with a breakdown into excellent, good, fair and poor. 33 patients with type B and C injuries (Tile) underwent evaluation with this scoring system. We found 15 excellent, 10 good, 2 fair and 6 poor results. The score showed that patients' most frequent handicap was pain (median 60% of maximum score). Hip mobility was hardly affected, and from the radiological point of view it appeared that alterations of pelvic symmetry and symphysis were most common. Our proposal is to apply this scoring system on a wide basis, because only with a great number of patients can the effectiveness of the score be tested and different ways of treatment assessed with regard to early and late results. Our system could be a useful contribution to sufficient quality control, particularly after such complex and severe injuries.

Activities of Daily Living↗
PubMed1993

Quality control in colonoscopy: a Singapore perspective.

For quality control purposes, a computer based auditing system for colonoscopy has been developed in the Department of Colorectal Surgery, Singapore General Hospital, Singapore. The first year's experience was reviewed to determine both workload patterns and the individual operators' performances. Colonoscopic completion rates, both as raw data and cusum transformations, were used as indices of quality control. The mean colonoscopic completion rate for the Unit was 97.0% and, when temporal trends were analysed by cusum, all operators consistently met or exceeded the minimum target completion rate of 90%.

Colonoscopy↗
PubMed1982

[Results of quality control surveys for urinary calculus analyses].

In 1980 and 1981, four quality control surveys for urinary calculus analyses were carried out, within the framework of external quality controls of the Deutsche Gesellschaft für Klinische Chemie. During these quality control surveys the participating laboratories received a total of 16 samples (eight pure substances and eight mixtures of two components), to be analyzed qualitatively and quantitatively. For the qualitative analyses, a laboratory could provide simplified descriptions of the analytes - for example, without stating the number of molecules of the water of crystallization; or, to the extent permitted by the mode of analysis, the exact chemical composition could be presented. Of 1283 analyses, 818 (64%) attained the goals of the simplified analysis. The most frequent errors in chemical analyses were false negative and false positive results for calcium oxalate, and false negative results for calcium phosphate. Laboratories using analysis by infrared spectroscopy also submitted the biggest proportion of incorrect analyses for these components. The most reliable results were produced by X-ray-diffraction: 86% of the results in this category represented correct differentiated analyses. The generally accurate results achieved by some participants using chemical analysis suggest, however, that - in addition to the principle of analysis used - the qualification of the operator is an important determinant in the reliability of the results.

Calcium Oxalate↗
PubMed1995

A novel comprehensive quality control instrument for medical accelerators.

A comprehensive quality control instrument for calibration of medical accelerators that use photon, electron, or proton beams in teleradiotherapy is described. It employs a fluorescence screen, mounted on a central stage with four degrees of freedom, monitored by a CCD camera. A single set-up of the instrument enables one to perform mechanical, light laser, and radiation tests, at arbitrary angles of the accelerator gantry. The new device provides for quantitative evaluation of the tests performed and provides for documentation of the test results in real time. The device provides significant time savings with concurrent improvement in accuracy for tests performed during installation and acceptance processes, and the implementation of quality control procedures for medical accelerators.

Electrons↗
PubMed2002

[Quality control in surgical pathology--analysis of a questionnaire].

To investigate the state of quality control in surgical pathology in Japan, we conducted a questionnaire survey of 80 pathology departments in universities and 275 laboratories in hospitals that are officially accredited by the Japanese Society of Pathology(JSC). The pathologists set a high valuation on guidelines for quality control published by JSC, but hardly ever followed these guidelines because of poor understanding and lack of pathologists on staff. We propose the development of a quality control manual that one pathologist can perform, the establishment of a substantial consultation system and seminars, and education on the importance of quality control for pathologists.

Humans↗
PubMedDate not supplied

[Quality control dose calibrators].

We have reviewed the legislation about the quality control of dose calibrator. The importance of verifying the correct work of these instruments, is fundamental in daily practice of radiopharmacy and nuclear medicine. The Spanish legislation establishes to include these controls as part of the quality control of radiopharmaceuticals, and the program of quality assurance in nuclear medicine. We have reviewed guides and protocols from international eminent organizations, summarizing the recommended tests and periodicity of them.

Calibration↗