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PubMed1995

Proton radiography as a tool for quality control in proton therapy.

Proton radiography is investigated for its use as a quality control tool in proton therapy. Images were produced both with range and range uncertainty information of protons passing through phantoms (Alderson phantom and a sheep's head). With the range images the correct positioning of the patient with respect to the beam could be verified. The range uncertainty images were used to quantitatively detect range variations of protons passing through inhomogeneities in the patient. These measurements can be used to indicate critical situations during proton therapy or to determine the safety margin around the tumor volume. With the range information the precision of different calibrations of computer tomography Hounsfield values to relative proton stopping power, used for proton treatment planning, was determined. It is found that the precision in range can be improved by a detailed analysis of the calibration data obtained from tissue-substitute measurements, by a factor of 2.5. The resulting range errors are in the order of the positioning precision (approximately 1 mm).

Animals↗
PubMed1986

Quality control for a 14- to 18-megohm-cm deionized water supply.

We studied the quality control for a 14- to 18-megohm-cm deionized water system with multiple outlets. The quality of water was determined by measuring specific resistance, performing a total colony count, trace metal analysis, and high-performance liquid chromatographic analysis. The specific resistivity of water was at the level of 17 to 18 megohms-cm at the recirculation loop and greater than 10 megohms-cm at the individual faucets. The microbial content was consistently less than 100 colony-forming units/mL. Periodic trace-metal analysis indicated less than 1 microgram/L of copper, bismuth, zinc, cadmium, mercury, thallium, and lead. High-performance liquid chromatographic analysis, as determined by the absorbance of the highest peak by ultraviolet and fluorescence spectroscopy, indicated less than or equal to 0.001 absorbance unit. Our experience suggests that maintaining laboratory water at 14 to 18 megohms using a plastic system with plastic faucets eliminates the likelihood of bacterial organic and trace-metal contamination of the water.

Chromatography, High Pressure Liquid↗
PubMed2006

[Quality control (QC) of CT on rail system (FOCAL Unit) with a micro-multi leaf collimator (mMLC) using new GafChromic film for stereotactic radiotherapy].

PURPOSE: Recent years, CT on rail system was reported to be useful as a tool for image-guided radiotherapy (IGRT). This system was clinically developed with the aim of stereotactic irradiation (STI) for brain, lung, liver, prostate and other sites. Quality assurance and quality control (QC) is an important issue in CT on rail system to assure geometric accuracies. The purpose of this study is to estimate the geometric accuracies of our CT on rail system using a detachable micro-multi leaf collimator (mMLC) with new type radiochromic films. Carrying out our original QC program, translational errors, setup reproducibility, beam misalignment and beam characteristics were evaluated. METHODS AND MATERIALS: We have studied with CT on rail system (FOCAL unit, Toshiba Medical systems, Tokyo, Japan) and mMLC unit (Accuknife, Direx Inc., Tokyo, Japan). We have developed original alignment phantom and small steel markers (2 mm phi) were implanted on its surface at certain intervals. Firstly, we have evaluated the accuracy of self-moving CT gantry and CT resolutions for cranio-caudal directions by changing slice thickness. And then using the phantom, we have measured the accuracy and reproducibility of geometric isocenter of the linac side and the CT gantry side by scanning the phantom. We have also measured the geometric changes of the common treatment couch by weight-loaded test (up to 135 kgw). To estimate dosimetric and geometric accuracies with the mMLC unit, the misalignment of the beam axes (gantry, collimator and couch rotation axis), mMLC leaf positions, and dose distributions for the verification plan were measured with new type GafChromic films (GafChromic-RTQA, ISP Inc., USA) and cylindrical phantom. The dose characteristics of the GafChromic film were also evaluated. RESULTS: The reproducibility of the self-moving CT gantry have a good agreement within 1 mm. Weight-load test have shown a good reliability within 2 mm at the common treatment couch. The translational precision of the common treatment couch was 0.0 +/- 0.1 mm at linac side and -0.2 +/- 0.5 mm at CT gantry side. The misalignments of beam axes have been kept within 0.4 mm at maximum. Gap test have shown the accuracies of the mMLC leaf positions, which is needed to keep within 1 mm by a routine calibration. CONCLUSIONS: To practice quality control program for the FOCAL unit and the mMLC unit is essential for a regular interval to reduce systematic errors. New type radiochromic film would be useful for a verification tool as alternative to conventional film.

Quality Control↗
PubMed2004

Seal of transparency heritage in the CISMeF quality-controlled health gateway.

BACKGROUND: It is an absolute necessity to continually assess the quality of health information on the Internet. Quality-controlled subject gateways are Internet services which apply a selected set of targeted measures to support systematic resource discovery. METHODS: The CISMeF health gateway became a contributor to the MedCIRCLE project to evaluate 270 health information providers. The transparency heritage consists of using the evaluation performed on providers that are referenced in the CISMeF catalogue for evaluating the documents they publish, thus passing on the transparency label from the publishers to their documents. RESULTS: Each site rated in CISMeF has a record in the CISMeF database that generates an RDF into HTML file. The search tool Doc'CISMeF displays information originating from every publisher evaluated with a specific MedCIRCLE button, which is linked to the MedCIRCLE central repository. Starting with 270 websites, this trust heritage has led to 6,480 evaluated resources in CISMeF (49.8% of the 13,012 resources included in CISMeF). CONCLUSION: With the MedCIRCLE project and transparency heritage, CISMeF became an explicit third party.

Abstracting and Indexing↗
PubMed2003

Designing and implementing quality control for multi-center screening of mutations in the ATM gene among women with breast cancer.

Epidemiologic studies of breast and other cancers are increasingly turning toward large, multi-center designs in order to obtain adequate power to detect low-penetrance susceptibility alleles. The size of such studies often makes it necessary to distribute the genetic screening efforts to multiple sites. Careful standardization of screening methodology and quality control across sites is required for such multi-center screening designs to be efficient. In this report, we illustrate our approach to these challenges in the context of the WECARE (Women's Environment, Cancer and Radiation Epidemiology) Study, a multi-center population-based genetic epidemiologic study of women with unilateral and bilateral breast cancer. We provide optimized conditions for screening the ataxia-telangiectasia gene (ATM) for variation by denaturing high-performance liquid chromatography (DHPLC) and describe the results of two independent quality control studies at four international centers employing these conditions. Finally, we report novel mutations in the ATM gene identified both in patients with ataxia-telangiectasia and in patients with unilateral or bilateral breast cancer.

Ataxia Telangiectasia Mutated Proteins↗
PubMed2004

Assessment of quality control parameters and interchangeability of multisourced metformin HCl tablets marketed in Nigeria.

A quality control assessment of five brands of metformin hydrochloride tablets marketed in Nigeria [Glucophage (R) (Merck, Quetta), Metformin BDC (Bangkok labs, Bangkok), Metformin (Medopharm, India), Glucophage (R) (Ilsan), Glucophage (Lipha)] was carried out in order to determine the brands that are interchangeable or switchable. The disintegration time, dissolution rate and absolute drug content were determined in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) without enzymes. The weight uniformity and hardness tests were also performed according to the official methods. A variation of the concept of dissolution efficiency (DE), known as predicted availability equivalent (PAE), was used to predict the likely in vivo bioavailability. Our results showed that all the five brands passed the uniformity of weight and disintegration tests. Dissolution efficiency was found to be higher in SGF than in SIF. In SGF, all the brands were bioequivalent. In SIF, all the brands, except Medopharm, were also bioequivalent. The study showed that four brands of metformin hydrochloride (Merck, BDC, Lipha and Ilsan) marketed in Nigeria are of acceptable standards and hence BDC, Lipha and Ilsan brands of glucophage are interchangeable with the innovator drug, glucophage R (Merck).

Chemistry, Pharmaceutical↗
PubMed1998

Quality control of dose volume histogram computation characteristics of 3D treatment planning systems.

Detailed quality control (QC) protocols are a necessity for modern radiotherapy departments. The established QC protocols for treatment planning systems (TPS) do not include recommendations on the advanced features of three-dimensional (3D) treatment planning, like the dose volume histograms (DVH). In this study, a test protocol for DVH characteristics was developed. The protocol assesses the consistency of the DVH computation to the dose distribution calculated by the same TPS by comparing DVH parameters with values obtained by the isodose distributions. The computation parameters (such as the dimension of the computation grid) that are applied to the TPS during the tests are not fixed but set by the user as if the test represents a typical clinical case. Six commercial TPS were examined with this protocol within the frame of the EC project Dynarad (Biomed I). The results of the intercomparison prove the consistency of the DVH results to the isodose values for most of the examined TPS. However, special attention should be paid when working with cases of adverse conditions such as high dose gradient regions. In these cases, higher errors are derived, especially when an insufficient number of dose calculation points are used for the DVH computation.

Europe↗
PubMed1976

Long-term reproducibility of a new pH/blood-gas quality-control system compared to two other procedures.

The long-term precision and stability of a new quality-control system for blood pH and gas measurements are compared to that of tonometered bicarbonate solutions and serum-based preparations. The new system, consisting of gas-equilibrated bicarbonate solutions in glass ampuls, is shown to be as stable as the serum-based preparation, and as reproducible as either of the other methods. The new system, offering three discrete sets of control values, has certain advantages in the simultaneous quality of pH, carbon dioxide tension, and oxygen tension measurements.

Blood↗
PubMed1988

Internal quality control, proficiency testing, and the clinical relevance of laboratory testing.

Estimates of instrument-specific analytical performance for measurement of four chemistry analytes (calcium, cholesterol, creatinine, and glucose) were derived from 21 quality control programs that utilized the College of American Pathologists Quality Assurance Service and from 12 College of American Pathologists Comprehensive Chemistry Survey sets. The quality control-derived estimates of analytical bias were larger and level-dependent when compared with the survey results. Possible explanations for these differences include "matrix effects" due to glycol stabilization of the control materials studied and analyst bias when testing survey specimens. A number of instruments from the Quality Assurance Service pools failed to meet the allowable analytical error goals for calcium and creatinine that serve as the basis for the "fixed limits" evaluation criteria of the survey program. The methods for glucose analysis met the prescribed evaluation limits. Cholesterol analyses need significant improvement to meet the analytical requirements of long-term testing of individuals.

Blood Glucose↗
PubMed1999

Posttranslational quality control: folding, refolding, and degrading proteins.

Polypeptides emerging from the ribosome must fold into stable three-dimensional structures and maintain that structure throughout their functional lifetimes. Maintaining quality control over protein structure and function depends on molecular chaperones and proteases, both of which can recognize hydrophobic regions exposed on unfolded polypeptides. Molecular chaperones promote proper protein folding and prevent aggregation, and energy-dependent proteases eliminate irreversibly damaged proteins. The kinetics of partitioning between chaperones and proteases determines whether a protein will be destroyed before it folds properly. When both quality control options fail, damaged proteins accumulate as aggregates, a process associated with amyloid diseases.

Adenosine Triphosphatases↗
PubMed1982

The influence of radiation therapy quality control on survival, response and sites of relapse in oat cell carcinoma of the lung: preliminary report of a Southwest Oncology Group study.

Two hundred and ninety-eight patients with limited (confined to chest and supraclavicular area, encompassable by a single radiation portal) small cell carcinoma of the lung were entered on Southwest Oncology Group Protocol 7628. Patients were treated with multi-agent chemotherapy and radiation therapy with or without BCG. Radiation therapy quality control analysis, including dosimetric reconstruction and port film review was introduced after the protocol was activated and was retrospectively applied. Patients who were considered major protocol variations had statistically worse survival (40 weeks versus 60 weeks; P = .002), a lesser improvement in response rate after induction chemotherapy (27 versus 48%; P = .05) and a higher chest failure rate (77 versus 55%; P = .047) than evaluable patients. Five patients relapsed in the brain, all associated with chest failure. Quality control is essential in cooperative group studies.

Antineoplastic Agents↗
PubMed2001

Distinct retrieval and retention mechanisms are required for the quality control of endoplasmic reticulum protein folding.

Proteins destined for the secretory pathway must first fold and assemble in the lumen of endoplasmic reticulum (ER). The pathway maintains a quality control mechanism to assure that aberrantly processed proteins are not delivered to their sites of function. As part of this mechanism, misfolded proteins are returned to the cytosol via the ER protein translocation pore where they are ubiquitinated and degraded by the 26S proteasome. Previously, little was known regarding the recognition and targeting of proteins before degradation. By tracking the fate of several mutant proteins subject to quality control, we demonstrate the existence of two distinct sorting mechanisms. In the ER, substrates are either sorted for retention in the ER or are transported to the Golgi apparatus via COPII-coated vesicles. Proteins transported to the Golgi are retrieved to the ER via the retrograde transport system. Ultimately, both retained and retrieved proteins converge at a common machinery at the ER for degradation. Furthermore, we report the identification of a gene playing a novel role specific to the retrieval pathway. The gene, BST1, is required for the transport of misfolded proteins to the Golgi, although dispensable for the transport of many normal cargo proteins.

Animals↗
PubMed1988

Water quality control trials: statistical tables for direct comparison between membrane filtration bacterial counts and the multiple tube method with a description of the bacteriological method.

Experiments in the quality control of water samples are being conducted in the Public Health Laboratory Service and the water industry in the United Kingdom. The number of distributions which have been made is 7 and 92 laboratories are now participating. The methods used for preparing and distributing samples are described. Some participating laboratories use the multiple tube method and some use membrane filtration to assess the presence of coliforms and Escherichia coli. The results are, therefore, a mixture of estimated numbers and direct colony counts. In order to compare results from these two different laboratory methods statistical tables have been compiled to show the most likely multiple tube result corresponding to each colony count. Tables relating to two commonly used tenfold dilution series are presented. To illustrate how these tables may be used we present results from a typical quality control distribution. The analyses of these results are generally satisfactory but show a tendency for lower counts using the membrane filtration method and more false negative results with E. coli counts.

Colony Count, Microbial↗
PubMed2006

[Image registration for radiation therapy: Practical aspects and quality control].

The development of conformal radiotherapy techniques (CRT) and intensity modulated CRT requires an accurate delineation of target structures and organs at risk. Thus, additional information provided by anatomical and/or functional imaging modalities can be used for volume of interest determination combined with traditionally used Computed Tomography imaging (CT): for instance, functional or morphological Magnetic Resonance Imaging (f MRI or m MRI) or Positron Emission Tomography (PET). A prerequisite to the simultaneous use of this information is image registration. Due to the differences between the images and the information they provide, a quality control of image registration process for radiotherapy is mandatory. The purpose of this article is to present the difficulties in implementing such controls and to show the necessity for a clinical validation on patient's images. The last part of this work presents the possible interest in using f MRI to help radio-oncologists in the treatment planning for gliomas associated to image coregistration and quality control considerations.

Brain Neoplasms↗
PubMedDate not supplied

Adverse effect versus quality control of the Fuenzalida-Palacios antirabies vaccine.

We evaluated the components of the Fuenzalida-Palacios antirabies vaccine, which is till used in most developing countries in human immunization for treatment and prophylaxis. This vaccine is prepared from newborn mouse brains at 1% concentration. Even though the vaccine is considered to have a low myelin content, it is not fully free of myelin or of other undesirable components that might trigger adverse effects after vaccination. The most severe effect is a post-vaccination neuroparalytic accident associated with Guillain-Barré syndrome. In the present study we demonstrate how the vaccines produced and distributed by different laboratories show different component patterns with different degrees of impurity and with varying protein concentrations, indicating that production processes can vary from one laboratory to another. These differences, which could be resolved using a better quality control process, may affect and impair immunization, with consequent risks and adverse effects after vaccination. We used crossed immunoelectrophoresis to evaluate and demonstrate the possibility of quality control in vaccine production, reducing the risk factors possibly involved in these immunizing products.

Cell Culture Techniques↗
PubMed1990

Leukocyte immunophenotyping by flow cytometry in a multisite study: standardization, quality control, and normal values in the Transfusion Safety Study. The Transfusion Safety Study Group.

The Transfusion Safety Study (TSS) is a multicenter, cooperative investigation of factors that may determine the occurrence and modify the expression of transfusion-transmitted infections. A flow cytometry laboratory was established in each of the six participating centers in order to avoid alterations in cell phenotypes which may be caused by shipping delays, temperature changes, and handling. As a consequence, in order to assure compatibility of results, stringent standardization, quality control, and proficiency testing procedures were developed. This paper documents (i) the effect of time from phlebotomy to specimen staining and then to analysis for the antibodies used in the study; (ii) the effects of variations in light scatter cursor location for certain antibodies; (iii) a quality control program and data management and analysis system, each specifically designed for the study; and (iv) presents extensive data on age- and sex-related reference (normal) ranges for the several individual and paired monoclonal antibodies used in the study. Problems encountered, including obtaining reliable absolute lymphocyte counts, interference by nucleated erythrocytes, and sources of variability in results, are discussed. This study is meant to serve as a reference for future TSS publications.

Blood Transfusion↗
PubMed2002

Biological UV dosimeters in quality control of tanning tubes.

Although according to the International Radiological Protection Association-International Non-Ionizing Radiation Committee recommendation (1991) the use of sunbeds for cosmetic purposes is not recommended, tanning devices are used widely. Ten different types of commercially available sunbed tubes have been studied using a uracil biological UV dosimeter, and three of them were analyzed in detail. Dimerization effectiveness of the tubes was measured directly, whereas efficiency of erythema induction was calculated weighting the emission spectra by the Commission Internationale de l'Eclairage erythema action spectrum. The data obtained demonstrate that quality control of sunbed tubes has to include not only the determination of the UV doses administered but also the assessment of the health risk due to the UVB and UVA components of the lamp. A method of quality control using the uracil biological dosimeter was elaborated, and the estimation of the "acceptable" exposure time was checked/controlled on 15 volunteers by assessing individually the erythema induction threshold. A correct classification of the sunbed tubes is proposed by characterizing the erythema induction versus DNA-damaging effectiveness of tubes.

Heliotherapy↗
PubMed2002

The importance of trimming reactions on asparagine-linked oligosaccharides for protein quality control.

Although the biochemistry of early trimming reactions by glucosidases and ER mannosidases occurring on asparagine-linked oligosaccharides has been known for a long time, their involvement in quality control of protein folding has become apparent only more recently. Here we review the evidence for the involvement of specific oligosaccharide trimming intermediates such as Glc(1)Man(9)GlcNAc(2) and Man(8)GlcNAc(2) B isomer in this fundamental cellular process and the subcellular distribution of components of the protein quality control machinery which indicates the involvement of both the ER and pre-Golgi intermediates in this process. In addition, recent studies on the subcellular distribution of endomannosidase in conjunction with previously obtained biochemical data will be reviewed which demonstrate that an alternative deglucosylation pathway exists in pre-Golgi intermediates and the Golgi apparatus.

Animals↗