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At least 379 records · Page 21Linked to original sources
PubMed2002

A quality control program for MR-guided focused ultrasound ablation therapy.

In this study, we propose a quality control program for MR-guided focused ultrasound (FUS) ablation treatment to assess FUS beam positioning accuracy, FUS power delivery accuracy, MR imaging quality, and FUS ablation system safety. A total of 353 sonication points in Lucite cards were measured, the average placement errors were -0.06 mm in the SI direction and -0.04 mm in the LR direction. Temperature elevation was calculated from MR phase difference images and the measured water proton chemical shift (WPCS) temperature coefficient. WPCS temperature calibration for phantoms yielded a temperature coefficient of 0.011 ppm/degree C. Sixteen experiments were conducted using six different phantoms to test the reliability of FUS power delivery. SNR and RF power calculated from phantom images were analyzed and stored at the MR console. A computer program was developed to integrate the system power delivery and the MR image quality control into one automated process. In the clinical trial at our institution, we expect this quality control program to be carried out before each patient treatment. If measured quality control values exceeds or below the preset values, a system service and retest should be conducted before the treatment.

Equipment Design↗
PubMed2002

[Application of fingerprint chromatogram in quality control of Shen-Mai injection].

The theory and practice of traditional Chinese medicine require some comprehensive methods to assess quality of the Chinese herbal medication. Fingerprint chromatogram is one of the feasible approaches to evaluate the quality of Chinese herbal medication. So the fingerprint chromatogram of Shen-Mai injection was established by using reversed-phase high performance liquid chromatography. The chromatographic conditions were as follows: a Hypersil C18 column was used; the mobile phase was composed of water (A) and acetontrile (B) with linear gradient elution (0-50 min, 5%-95% B, volume fraction); the flow rate was 1.0 mL/min and the UV absorbance detection was set at 202 nm. The peak-area ratios of twenty-three fingerprint peaks and internal standard (diphenyl) were taken as the criteria for quality control. The quality differences in various batches and various manufacturers of Shen-Mai injections were investigated by projection discriminance based on principal component analysis. The results show the method developed is convenient, reliable and applicable for the quality control analysis of Shen-Mai injection.

Chromatography, High Pressure Liquid↗
PubMed1998

Quality assurance and quality control in longitudinal studies.

As we have presented, it is evident that cohort studies are confronted with their own special, non-trivial issues of quality assurance and quality control. Such studies are typically large-scale designs and involve an extensive amount of data to be collected and processed, the quality of which depends on a variety of factors related to study personnel and equipment. The fact that data are collected over an extended period of time and at several centers greatly increases the magnitude of the data processing task, significantly increasing the likelihood of discrepancies and measurement error in the data. As presented in tables 1 and 2, the quality assurance and quality control procedures span the entire course of the study and include a multitude of tasks. Such tasks are delegated to various committees and/or are undertaken by participating centers, all of which must take responsibility for understanding, implementing, and following through on all procedures that maximize data quality. The quality of the quality assurance/quality control process is highly correlated with the quality of the communication within and between centers and all researchers. Maintaining standardization of procedures across centers and long-term stability of equipment and analytic procedures are integral components of quality control. In conclusion, the magnitude of the quality control process in a multicenter longitudinal study should not be underestimated, requiring a significant commitment of study resources. The quality control process is key to the integrity of the study, and an integral part of the design of the study. In a well-designed study, with a good quality control process and dedication to the process by the research team, the validity of the conclusions of the cohort study can be established.

Data Collection↗
PubMedDate not supplied

Multiformat video and laser cameras: history, design considerations, acceptance testing, and quality control. Report of AAPM Diagnostic X-Ray Imaging Committee Task Group No. 1.

Acceptance testing and quality control of video and laser cameras is relatively simple, especially with the use of the SMPTE test pattern. Photographic quality control is essential if one wishes to be able to maintain the quality of video and laser cameras. In addition, photographic quality control must be carried out with the film used clinically in the video and laser cameras, and with a sensitometer producing a light spectrum similar to that of the video or laser camera. Before the end of the warranty period a second acceptance test should be carried out. At this time the camera should produce the same results as noted during the initial acceptance test. With the appropriate acceptance and quality control the video and laser cameras should produce quality images throughout the life of the equipment.

Equipment Design↗
PubMed1991

Estimating the performance characteristics of quality-control procedures when error persists until detection.

The concepts of the power function for a quality-control rule, the error detection rate, and the false rejection rate were major advances in evaluating the performance characteristics of quality-control procedures. Most early articles published in this area evaluated the performance characteristics of quality-control rules with the assumption that an intermittent error condition occurred only within the current run, as opposed to a persistent error that continued until detection. Difficulties occur when current simulation methods are applied to the persistent error case. Here, I examine these difficulties and propose an alternative method that handles persistent error conditions effectively when evaluating and quantifying the performance characteristics of a quality-control rule.

Chemistry, Clinical↗
PubMed1986

The incorporation of red blood cell index mean data into quality control programs.

Patient red blood cell (RBC) index means, when used in quality control, form an independent standard that is as accurate and precise as preserved blood controls. If such patient data are routinely incorporated in intralaboratory and interlaboratory quality control programs, a substantial improvement in the present state-of-the-art is possible. Within the laboratory, each method serves to confirm the adequacy of the other. In interlaboratory control trials the combination makes it possible to specify the cause of most misanalyses. For similar reasons, the combination of both methods enables the manufacturer of quality control material to assess the adequacy of the manufacturing and value assignation process.

Blood Preservation↗
PubMed2002

Internal quality control of PCR-based genotyping methods: practical experiences.

Internal quality control programmes for genetic analyses are needed. We have focused on quality control aspects of selected polymorphism analyses used in thrombosis research. DNA was isolated from EDTA-blood (n = 500) and analysed for 18 polymorphisms by polymerase chain reaction (PCR), i.e. restriction fragment length polymorphisms, allele specific amplification, or amplification of insertion/deletion fragments. We evaluated the following aspects in the analytical procedures: sample handling and DNA-isolation (pre-analytical factors), DNA-amplification, digestion with restriction enzymes, electrophoresis (analytical factors), result reading and entry into a database (post-analytical factors). Furthermore, we evaluated a procedure for result confirmation. Isolated DNA was of good quality (42 micrograms/ml blood, A260/A280 ratio > 1.75, negative DNAsis tests). Occasionally, results were reanalysed because of positive reagent blanks (< 1%) or because of problems with the controls (< 5%). On confirmation, we observed four genotyping discrepancies. Control of data handling revealed 0.1% reading mistakes and 0.5% entry mistakes. Based on our experiences, we propose an internal quality control programme for widely used PCR-based haemostasis polymorphism analyses.

Genotype↗
PubMed1989

Efficacy of a home made quality control serum.

With increasing automation in Clinical Laboratories, the requirements for quality control material have greatly increased in order to monitor performance. The constant use of commercial control material is not economically feasible for many countries because of non-availability or the high cost of these materials. Here we describe a simple technique to prepare Home Made Quality Control serum using blood from polycythaemic patients. This preparation is stable for about six months without any alterations in the concentration of any of the chemical constituents. Extensive use of Home Made Quality Control sera in our laboratories have saved about 69% of the amount spent on the commercial material without any compromise in quality of the laboratory performance.

Blood↗
PubMed2005

External quality control program for semen analysis: Spanish experience.

PURPOSE: Results from an external quality control programme for semen analysis carried out in Spain are analysed. METHODS: Quality control materials were distributed and the following seminal parameters were determined: concentration, total motility, progressive motility, rapid progressive motility, morphology and sperm vitality. The between-laboratories coefficients of variation were assessed on different types of quality control material. RESULTS: The majority of participating laboratories utilised manual versus computer-assisted semen analysis methods. Some between-laboratories coefficients of variation ranges were: 20.8-33.8% for concentration (semen pool suspension); 13.9-19.2% for total motility (videotapes); 54.2-70.2% for sperm morphology (strict criteria using stained smears); and 9.8-41.1% for sperm vitality (stained smears). There was an inverse relation between mean percentage of sperm and coefficients of variation between laboratories for sperm motility, morphology and vitality. CONCLUSIONS: These data highlight the urgent need for improvement in the overall quality of andrology testing.

Clinical Laboratory Techniques↗
PubMed1981

Quality control of agar diffusion susceptibility tests. Data from the Quality Assurance Service Microbiology Program of the College of American Pathologists.

During the period from January 1979 through January 1981, 155 active participants in the Microbiology Program of the College of American Pathologists Quality Assurance Service (QAS) submitted approximately two million individuals determinations on three quality control reference strains. Of these determinations, 83% were obtained using the standardized disc-diffusion procedure of Bauer and co-workers, and, 6% using the agar overlay modification of Barry and associates. The mean and standard deviation for data obtained using these procedures were similar to those for data collected from the inception of the program in 1974 through December 1978. The number of individual determinations falling above or below existing control limits, however, was significantly less for the present data than for that previously reported. These differences result from a change in computation procedures. In the current report percentages of daily values exceeding the NCCLS limits were calculated using actual counts, whereas in the previous reports these percentages were estimated by accepting an assumption of Gaussian distribution.

Ampicillin↗
PubMed1983

Quality control of agar diffusion susceptibility tests: data from the Quality Assurance Service Microbiology program of the College of American Pathologists.

Over a 12-month period, between July 1981 and June 1982, 115 active participants in the Microbiology program of the College of American Pathologists Quality Assurance Service (QAS) submitted a total of 555,619 individual determinations on three quality control reference strains using the NCCLS standardized disc diffusion procedure. Data is presented for those antimicrobic agent/reference strain combinations for which NCCLS control limits have been changed since the last report of QAS microbiology data or that continue to show discrepancies with current NCCLS individual daily test control guidelines. Data for Escherichia coli versus cefoxitin, doxycycline, and nalidixic acid and for Staphylococcus aureus versus cefoxitin, nafcillin, and oxacillin show good compliance with the new NCCLS guidelines and distributions that are all approximately Gaussian. Significant discrepancies were noted for six combinations; cefamandole, cephalothin, neomycin, and nitrofurantoin versus E. coli and amikacin and clindamycin versus S. aureus. Of these discrepancies, only neomycin/E. coli and amikacin/S. aureus can be accounted for by a subpopulation of laboratories, which, when removed, corrects the data.

Amikacin↗
PubMed1991

Clinical trials and quality control: checkpoints in the provision of assistive technology.

Clinical trials and quality control measures are characterized by evaluation of assistive technology by users, and feedback to providers for the purpose of improving devices or service delivery. These processes recognize that consumer satisfaction is an important measure of device and service delivery effectiveness. In this article, types of clinical trials are reviewed, and both prospective and retrospective methods of quality control are presented. The authors take the position that rehabilitation engineering centers providing customized devices and adapted technology should implement quality control measures in order to improve services to their clients.

Clinical Trials as Topic↗
PubMed1993

[External national quality control of blood group typing 1983-92. Significance for quality assurance in transfusion medicine].

A programme for external quality control in blood group serology has been run in Norway since 1983 by the National Institute of Public Health. Uncomplicated AB0 and Rh(D) grouping, including Du typing, has been performed satisfactorily. Rh(D) grouping of presensitized, Rh (D) negative cells is still a problem, but one which has been reduced significantly. Both indirect and direct antiglobulin reactions have given about 15% false negative results, mainly with weak antibodies and weakly sensitized cells. Poor training of technicians in reading weak agglutination reactions may be an important source of error. The importance of post-graduate training of blood bank staff is emphasized.

ABO Blood-Group System↗
PubMed1994

Quality control in image cytometry: DNA ploidy.

DNA ploidy has become a commonly performed quantitative image cytometry test in microscopic pathology. This has led to the need to develop quality control procedures to aid in assuring uniform and reliable test results. There are a number of unique issues related to the emerging technology of image analysis and its routine use as a quantitative microscopic assay that require consideration before establishing a quality control program. Previous considerations of this topic have primarily related to measurement issues, e.g., accuracy comparisons to other methodologies, calibration of instrumentation, sources of measurement error, and the interpretation of measurements results. Although these issues are critically important, with more routine usage the focus is now turning to quality control of the overall testing process in everyday use. Control charts and methods of controlling the total measurement process such as have been used in clinical chemistry, need to be established. As one of the first image assays in pathology, quality control procedures established now for DNA ploidy measurements could help shape the development of this field, especially as pathology transitions from being a subjective visual microscopic inspection process to a quantitative measurement process. This paper discusses these issues as they relate to overall quality assurance for the DNA ploidy test and describes a quality control program developed for an active breast cancer testing laboratory specializing in image cytometry tests, including DNA ploidy. The quality control program includes calibration control charts, control charts for internal diploid controls, check samples, and computerized individual histogram interpretation.

Biopsy, Needle↗
PubMed2004

Quality control for spirometry in preschool children with and without lung disease.

The reliability of spirometry is dependent on strict quality control. We examined whether quality control criteria recommended for adults could be applied to children aged 2-5 years. Forty-two children with cystic fibrosis and 37 healthy children attempted spirometry during their first visit to our laboratory. Whereas 59 children (75%) were able to produce a technically satisfactory forced expiration lasting 0.5 second, only 46 (58%) could produce an expiration lasting 1 second, with the youngest children having the most difficulty. Start of test criteria for adults were inappropriate for this age group, with only 16 of 59 children producing a volume of back extrapolation as a proportion of forced vital capacity of less than 5%, whereas all but 4 could produce a volume of back extrapolation of 80 ml or less. More than 90% of children were able to produce a second forced vital capacity and a second forced expired volume in 0.75 second within 10% of their highest. Errors in the spirometry software resulted in inaccurate reporting of expiratory duration and inappropriate timed expired volumes in some children. We describe recommendations for modified start of test and repeatability criteria for this age group, and for improvements in software to facilitate better quality control.

Case-Control Studies↗
PubMed2006

Statistical quality control process for traditional Chinese medicine.

The statistical quality control process on raw materials and/or the final product of traditional Chinese medicine (TCM) is examined. We develop a statistical quality control (QC) method to assess a proposed consistency index of raw materials from different sources and/or final products manufactured at different sites. The idea is to construct a 95% confidence interval for a proposed consistency index under a sampling plan. If the constructed 95% confidence lower limit is greater than a prespecified QC lower limit, then we claim that the raw material or final products have passed the QC and hence can be released for further processing or use; otherwise, the raw materials and/or final product should be rejected. For a given component (the most active component if possible), a sampling plan is derived to ensure that there is a desired probability for establishing consistency between sites when there is truly no difference in raw materials or final products between sites. An example concerning the development of a TCM is presented to illustrate the proposed statistical QC method for assessing consistency in raw materials from two sites.

Algorithms↗
PubMed1996

Proposed guidelines for the internal quality control of analytical results in the medical laboratory.

The factors involved in analytical quality relate to definition of quality, creation of quality, and control of quality, and errors arise from external and internal sources as well as from permanent and variable factors. Further, the two main types of error are classified as systematic and random errors. Internal quality control (IQC) systems can only operate on the variable factors which are related to batch-to-batch variations (external factors) and to the performance in the laboratory (internal factors). In creating an adequate internal control system, several problems are faced: (i) quality of control materials, (ii) types and frequency of possible errors, (iii) number and types of control materials, (iv) number of replicates of the control, (v) probability of error detection, (vi) probability of false rejection, (vii) consequences of reject signals, (viii) trouble-shooting systems, and (ix) prevention of errors among many other conditions. Gaussian distributions of control results are assumed and the statistical control rules are evaluated in relation to probability of false rejections, Pfr, and probability of error detection, Ped, for the different rules. Combinations of low Pfr and high Ped are obtained by combining results from e.g. four measurements of the same control sample by use of mean and range rules. Further, it is not possible to establish a common control system which can be used for all quantities and analytical procedures; on the contrary, each procedure should have its particular efficient IQC system. These aspects are discussed and a number of guidelines for statistical control rules and problem related internal quality control are presented.

Guidelines as Topic↗
PubMedDate not supplied

Technical aspects of screen-film radiography, film processing, and quality control.

The broad goal of quality control (QC) of screen-film radiography and film processing is to provide radiographs of consistent, high quality. Achievement of this goal requires attention to several areas, including QC of the screen-film system and photographic processor, acceptance testing of all components, and skill in analysis of film artifacts to "diagnose" the processor problems causing the aberrations. Methods to reduce waste, recycle by-products, and reuse resources such as silver are also part of the QC process. To optimize the photographic process, one should use the film, chemical solutions, processor, and screens and cassettes produced by one manufacturer or the combination recommended by the film manufacturer. Important variables in film processing (eg, density, density difference, and base plus fog) are recorded on control charts, which plot the variables as a function of time and allow easy analysis of changes in operating levels. Many variables can affect any component in the screen-film imaging system; problems caused by manufacturing batch-to-batch variation, which is perhaps the most pervasive variable, can be lessened by purchasing film, screens, and cassettes in large batches and of the same batch and by purchasing photographic chemicals in concentrated form and mixing them as needed. Acceptance testing ensures that the product meets expectations, ensures that its performance meets specifications, and establishes the operating level for the ongoing QC program.

Artifacts↗