Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “quality control”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,081 records · Page 60Linked to original sources
PubMed1993

Quality assurance and quality control methods for animal and human applications of no-carrier-added 6-[18F]fluorodopa for PET investigations of dopaminergic systems.

No-Carrier-Added (NCA) 6-[18F]fluoro-L-dopa (6-FDOPA) is being produced routinely for PET investigations of dopaminergic systems at our Institute. We describe here in detail the quality assurance methods involved in its multi-step developmental stage as a radiopharmaceutical. A method to remove toxic copper ions to prepare an injectable solution is described. The stability and shelf-life of NCA 6-FDOPA was also examined and results are discussed. Quality control involved three major aspects: (a) chemical purity, (b) radiochemical purity and (c) enantiomeric excess. A method for quick quality control of individual batch preparations is described.

Animals↗
PubMed2006

Feasibility and reproducibility of an image-scoring method for quality control of fetal biometry in the second trimester.

OBJECTIVES: The need for training programs and certification processes in fetal ultrasound has become obvious. The purpose of this study was to evaluate the feasibility of a score-based quality control system for fetal biometry in the second trimester. METHODS: Standard measurements of biparietal diameter and head circumference, abdominal circumference, and femur length at 20-24 weeks had been made by four operators using the same ultrasound machine. Twenty-five of each of the cephalic, abdominal and femoral images with the calipers in place were selected arbitrarily from each operator's ultrasound database and anonymized. These 300 images were analyzed by three experienced reviewers blinded to the operator's identity. Each image was first evaluated subjectively and then scored according to six criteria for abdominal and cephalic measurements and four criteria for femur length making a six-point score for abdominal and cephalic biometry and a four-point score for femur length. For subjective evaluation, inter-reviewer differences were analyzed using percentage agreement and adjusted kappa. For objective evaluation, a difference in scoring of one point or less among reviewers was considered good agreement. Intrareviewer variability was assessed using 40 images of each type of examination selected arbitrarily. RESULTS: The distribution of scores was similar between reviewers. One operator obtained significantly lower scores whereas the other three had good and comparable results. There was no statistical difference in the mean score attributed by each reviewer and agreement was good in 84-90% of the cases. Intrareviewer agreement was good in 90-100% of the cases, with similar scores for each reviewer. CONCLUSION: A quality control policy based on image scoring is feasible and allows for fair to good inter- and intrareviewer reproducibility. The potential contribution of this approach to assess the quality of routine ultrasound examinations should be tested on a larger scale.

Abdomen↗
PubMed2002

Construction of optimal quality control for oligo arrays.

MOTIVATION: Oligo arrays are important experimental tools for the high throughput measurement of gene expression levels. During production of oligo arrays, it is important to identify any faulty manufacturing step. RESULTS: We describe a practical algorithm for the construction of optimal quality control designs that identify any faulty manufacturing step. The algorithm uses hillclimbing, a search technique from combinatorial optimization. We also present the results of using this algorithm on all practical quality control design sizes. AVAILABILITY: On request from the authors.

Algorithms↗
PubMed1996

Quality control in diagnostic radiology--a United States perspective.

The world of diagnostic imaging is rapidly changing. Advances in established imaging modalities as well as the introduction of new imaging techniques are providing more specialised diagnostic tools for the clinician. Equipment performance and safety are still important to the management of this new technology, and quality control is a proven tool for monitoring these aspects. This paper reviews the current state of knowledge on quality control of imaging systems (albeit from a United States perspective), discussing radiography and fluoroscopy, interventional fluoroscopy, computed tomography (conventional and spiral), mammography and computed radiography.

Female↗
PubMed2005

Interpretation of high-throughput liquid chromatography mass spectrometry data for quality control analysis and analytical method development.

An approach to rapidly process and interpret high-throughput liquid chromatography mass spectrometry data is presented. This approach applies an in-house developed computer application to process LC-MS report files containing spectral and chromatographic data from four different detectors (i.e. electrospray positive ionization, electrospray negative ionization mass spectrometry, UV absorption, and evaporative light scattering detection). Properties characteristic of detection and chromatographic retention are extracted and populated into a database. Approaches to applying this analytical information database for quality control analysis of ca. 400,000 samples are presented. Compound quality assessment methods employing average purity and detection data fields are compared to methods employing multiple quality control criteria (e.g. detection, purity, retention, and signal to noise). Structural similarity searches were applied with the analytical information database to identify compounds that may be undetectable by electrospray mass spectrometry. In addition, an approach to applying the database to aid in the selection of analytical detection and chromatography conditions for rapid analytical method development is also discussed.

Chromatography, Liquid↗
PubMed1991

Medicaid program: Medicaid eligibility quality control program--HCFA. Response to comments on final rule.

This document responds to public comments received by the Department on a final rule issued on May 31, 1990, relating to the Department's decision not to publish regulations on the basis of the results of congressionally mandated studies of the quality control systems for the Aid to Families with Dependent Children (AFDC) program and the Medicaid program. The purpose of the studies, which were required by the Consolidated Omnibus Budget Reconciliation Act of 1985, was to examine how best to operate quality control systems in order to obtain information which would allow program managers to improve the quality of administration and provide reasonable data on which to base withholding Federal matching payments for excessive levels of erroneous State payments.

Centers for Medicare and Medicaid Services, U.S.↗
PubMed1995

Quality control of cathode-ray tube monitors for medical imaging using a simple photometer.

As computer monitors are used more in medical imaging and the use of picture archiving and communication system workstations with multiple monitors is increasing, quality control protocols become necessary to track subtle variations in performance characteristics. Several tests based on previously published work were applied to 10 monitors of three different types over a period of 5 months. Each test is explained, and the results are shown. For example, without corrective adjustments, 2 monitors from the same workstation showed a small but steady decline in maximum luminance of 8.1% and 7.6% over the course of 11 weeks that was not perceptible. From this experience, we took the first step toward developing a practical and useful quality control protocol. The proposed protocol requires only a photometer and the ability to generate the Society of Motion Picture and Television Engineers (SMPTE) test pattern, and takes approximately 5 minutes per monitor per week to gather data.

Data Display↗
PubMed1999

[National quality control of genomic HLA typing].

Since 1996 the Immunogenetics Laboratory of the National Cancer Institute/CBA, Genoa, in collaboration with the Immunohematology Research Centre of Bergamo has organized on behalf of Associazione Italiana di Immunogenetica e Biologia dei Trapianti (AIBT) and Istituto Superiore di Sanità (ISS) the quality control programme of HLA genomic typing for class I and II antigens for the laboratories performing HLA typing for organ and bone marrow transplantations. Herewith are reported the results and comments to the 1997 quality control programme along with some overall data.

Accreditation↗
PubMed1992

[Results of the quality control of magnetic resonance images].

The results are reported of an image quality control performed by the Medical Physics Dept. of Spedali Civili, Brescia, Italy, after the implementation of an MR unit (Siemens-Magnetom 1.5 T) in the Radiology Department. Image quality parameters were evaluated, with the methods suggested in literature, for test objects images acquired in the conventional projections (axial, sagittal, and coronal) using RF body and head coils. Our aim was to evaluate system evolution during optimization of the equipment and to identify, when possible, eventual situations of stability and the time needed to achieve them. The results obtained for the uniformity and the signal-to-noise ratio parameters are evaluated as time curves with the analysis of linear regressions of parameters evolution over time. The measurements were made over a 14-month period, on a fortnight basis. The long-term variations are emphasized. The uniformity parameter exhibits no significant changes over time, while signal-to-noise ratio tends to increase, mostly due to noise decrease. Noise was observed to stabilize in the last months. A second analysis, with a statistical test on the difference of two subsequent measurements, was carried out to confirm this trend. Stability periods could be identified for all parameters. As for noise, in particular, a stability interval from May to October 1990 confirmed the regression results. A normality range was defined in this period as a reference for subsequent measurements.

Magnetic Resonance Imaging↗
PubMed2006

Recommendations on detectors and quality control procedures for brachytherapy beta sources.

BACKGROUND AND PURPOSE: It is estimated that one third of the institutes applying clinical beta sources does not perform independent dosimetry. The Netherlands commission on radiation dosimetry (NCS) recently published recommended quality control procedures and detectors for the dosimetry of beta sources. The main issues of NCS Report 14 are summarized here. MATERIALS AND METHODS: A dosimetry survey was performed among 23 institutes in The Netherlands and Belgium. Well ionization chambers, a plastic scintillator, plane-parallel ionization chamber, diode and radiochromic film were used for determination of source strength (dose rate at reference distance) and uniformity of intravascular and ophthalmic sources. The source strength of multiple sources of each type was measured and compared with the source strength specified by the manufacturer. RESULTS: The standard deviation of the difference between measured and specified source strength was mostly about 3%, but varied between 0.8 and 15.8% depending on factors such as source type, detector, phantom and manufacturers calibration. The average non-uniformity was about 7% for intravascular sources and 20% for ophthalmic sources. It is estimated that the total relative standard uncertainty can be kept below +/-4% (1 sigma) with all detectors tested. Maximum deviations in source strength of 10% and a non-uniformity below 10% (intravascular) and 30% (ophthalmic) are recommended. CONCLUSIONS: Dosimetric and non-dosimetric quality control procedures on beta sources are recommended. They enable standardized measurements, including the determination of relative source strength and non-uniformity. Absolute calibrations depend on the future introduction of primary standards for clinical beta sources.

Belgium↗
PubMed2006

External quality control results of urine dip-slide devices.

Urinary tract infections are frequently diagnosed by using urine dip-slide devices, especially in medical practices and small laboratories. We performed a retrospective analysis of more than 3000 results obtained by several urine dip-slide devices during external quality control surveys. We found that an underestimation of bacterial counts and a difficulty in identifying mixed flora were relatively more frequent in medical practices than in specialized laboratories, and that regular participation in external quality control surveys correlates with better performances.

Bacteria↗
PubMed1999

MR relaxometry on a whole-body imager: quality control.

Long-term monitoring of the average proton relaxation time T2 of phantoms measured on a Siemens MR whole-body imager showed very good repeatability and reproducibility. The repeatability (short-term precision) and reproducibility (long-term precision) of the average values of a relaxation time T2 approximately/= 81 ms, obtained by a standard 16-echo CPMG pulse sequence, were 2.6% and 9.7%, respectively. The Siemens Vision imager proved to be a suitable tool for T2 evaluation in vivo. Quality control was performed using the techniques of control diagrams developed by Shewhart, which proved to be an appropriate method for continuous quality control of relaxation time determination.

Magnetic Resonance Spectroscopy↗
PubMed2000

A quality control procedure for force platforms.

A force platform is a technical method of quantitatively assessing balance indirectly. The use of force platforms in physiotherapy departments has become more prominent over the last few years. However, the main drawback in the use of force platforms is the lack of comprehensive calibration procedures, which casts doubt on the results obtained with these systems. Existing calibration tests are limited to testing the spatial accuracy of the force platform. This paper describes a comprehensive quality control test procedure which was developed. It is proposed that the developed quality control test procedure could be used to test all types of force platform and it includes a description of how the tests should be carried out, the frequency with which they should be carried out and the expected performance for each of the tests as recommended for the most part by the Association Francaise de Posturologie.

Biomechanical Phenomena↗
PubMed2002

[Quality control of intensity modulated treatments in radiotherapy].

Since January 2001, radiotherapy treatments with modulated intensity beams (IMRT) have started at the Centre Oscar-Lambret. This paper presents the tests and measurements made before the clinical implementation as well the quality control performed before each routine treatment. We use the treatment planning system Helax-TMS (MDS-Nordion) and the Primus accelerator (Siemens) linked to the Lantis network with Primeview and Simtec modules (Siemens) allowing to deliver intensity modulated beams with Step-and-Shoot technique. A prostate case and a head and neck case have been studied and have permitted to evaluate the benefit of IMRT compared to a "classical" conformal radiotherapy. In a second time, we have tested the accelerator's capabilities to deliver these intensity modulated beams, id-est, the accuracy of the leaf positions and the linearity of the monitor chamber. The third step has been the verification of the dose distributions calculated by Helax-TMS, id-est, the dose for different segment sizes, the dose profiles for an intensity modulated beam and the dose distribution for all the traitment beams. The used phantom has been especially developed at the Centre Oscar-Lambret for IMRT. The results have allowed to start clinical treatments and to establish a quality control set for this technique. The next step is the real time dosimetry with a portal imager.

Humans↗
PubMed2002

Quality control in management of pain.

Since 1987 several pain clinics in The Netherlands have started with some kind of computer-assisted recording of data, mainly for purposes of quality control. However, this has not yet led to routinely generated reports about the quality of these clinics because a consensus on how to assess quality in pain-treatment is missing. Using classical system-development methods a global specification for an information system for quality assessment was defined on which a prototype application was based. Various changes were adopted into this prototype, which ultimately resulted in explicit requirements stating: 1. Which data to record, 2. What organisational prerequisites to fulfil for such a system, 3. The user-interface, and 4. Interactions with other information systems. The final application was implemented in a number of pain clinics where its usefulness in quality control is currently assessed.

Benchmarking↗
PubMed2005

Real-time quality control of tracked ultrasound.

The overwhelming majority of intra-operative hazard situations in tracked ultrasound (US) systems are attributed to failure of registration between tracking and imaging coordinate frames. We introduce a novel methodology for eal-time in-vivo quality control of tracked US systems, in order to capture registration failures during the clinical procedure. In effect, we dynamically recalibrate the tracked US system for rotation, scale factor, and in-plane position offset up to a scale factor. We detect any unexpected change in these parameters through capturing discrepancies in the resulting calibration matrix, thereby assuring quality (accuracy and consistency) of the tracked system. No phantom is used for the recalibration. We perform the task of quality control in the background, transparently to the clinical user while the subject is being scanned. We present the concept, mathematical formulation, and experimental evaluation in-vitro. This new method can play an important role in guaranteeing accurate, consistent, and reliable performance of tracked ultrasound.

Algorithms↗
PubMed1988

Quality control of hemoglobin-based blood substitutes.

Preparation and use of hemoglobin-based blood substitutes, from stroma-free hemoglobin (SFH or Hb) and its DPG analogue-modified derivatives (PLP-Hb, ATP-Hb etc.) without thorough characterization and quality control in animal or human testing have produced, and may continue to produce, artifacts in the finished product. Thus the development of such a natural substitute for the volume expansion and oxygen delivery functions of the blood will be impeded. A case is made for the use of affinity purified hemoglobin and modified hemoglobin as standard starting materials for the preparation of Hb-based blood substitute(s) in general, and in particular poly PLP-Hb. Development of a commercial scale blood-substitute is only possible after the safety and toxicity issues of substitutes have been resolved by applying rigorous quality control.

Adenosine Triphosphate↗
PubMed1995

Daily dosimetric quality control of the MM50 Racetrack Microtron using an electronic portal imaging device.

The MM50 Racetrack Microtron, suited for advanced three-dimensional conformal radiotherapy techniques, is a complex machine in various respects. Therefore, for a number of gantry angles, daily quality control of the absolute output and fluence profiles of the scanned beams are mandatory. For the applied photon beams, a fast method for these daily checks, based on dosimetric measurements with the Philips SRI-100 Electronic Portal Imaging Device (EPID), has been developed and tested. Open beams are checked for four different gantry angles; for gantry angle 0, a wedged field is checked as well. Performing and analyzing the measurements takes about 10 min. The applied EPID has favourable characteristics for dosimetric quality control measurements: absolute output measurements reproduce within 0.5% (1 SD) and the reproducibility of relative (2D) beam profile measurements is 0.2% (1 SD). The day-to-day sensitivity stability over a period of one month is 0.6% (1 SD). Measured grey scale values are within 0.2% linear with the applied dose. The 2D fluence profile of the 25 MV photon beam of the MM50 is very stable in time: during a period of 5 months a maximum fluctuation of 2.2% has been observed. Once, a deviation in the cGy/MU-value of 6% was detected. There is no interlock in the MM50-system that would have prevented patient treatment with this strongly deviating output. Based on the results of this study and on clinical requirements regarding acceptability of deviations of beam characteristics, a protocol has been developed including action levels for additional investigations and, if necessary, adjustment of the beam characteristics.

Calibration↗