Quality Control Protocols Research Articles

Challenges for Coring Deep Permafrost on Earth and Mars

A scientific drilling expedition to the High Lake region of Nunavut, Canada, was recently completed with the goals of collecting samples and delineating gradients in salinity, gas composition, pH, pe, and microbial abundance in a 400 m thick permafrost zone and accessing the underlying pristine subpermafrost brine. With a triple-barrel wireline tool and the use of stringent quality assurance and quality control (QA/QC) protocols, 200 m of frozen, Archean, mafic volcanic rock was collected from the lower boundary that separates the permafrost layer and subpermafrost saline water. Hot water was used to remove cuttings and prevent the drill rods from freezing in place. No cryopegs were detected during penetration through the permafrost. Coring stopped at the 535 m depth, and the drill water was bailed from the hole while saline water replaced it. Within 24 hours, the borehole iced closed at 125 m depth due to vapor condensation from atmospheric moisture and, initially, warm water leaking through the casing, which blocked further access. Preliminary data suggest that the recovered cores contain viable anaerobic microorganisms that are not contaminants even though isotopic analyses of the saline borehole water suggests that it is a residue of the drilling brine used to remove the ice from the upper, older portion of the borehole. Any proposed coring mission to Mars that seeks to access subpermafrost brine will not only require borehole stability but also a means by which to generate substantial heating along the borehole string to prevent closure of the borehole from condensation of water vapor generated by drilling.

SU‐GG‐I‐71: Acceptance and Routine Quality Control in Direct Radiography Systems: Initial Experiences with the Italian Association of Physicist in Medicine Protocol

Medical x‐ray imaging systems must be designed to guarantee that maximum image quality is obtained for an acceptable radiation risk to the patient, and quality assurance (QA) procedures are used to ensure these standards are maintained. A quality control protocol for direct digital radiography (DDR) systems is described and discussed. A software to automatically process and analyze the required images for controls was developed, too. In this poster the initial results obtained on equipments of different DDR manufacturers were reported. In order to establish a generally acceptable baseline performance of the systems, fourteen different commercially available DDRs from four different manufactures were periodically tested and their results compared in the frame of the Digital Quality Assurance Task Group of the Italian Association of Physics in Medicine (AIFM). The protocol, designed to be performed in short time (all the tests were done in a clinical environment), seem to be able to highlight discrepancies from the standard operating performances.

Automated quality control protocol for MR spectra of brain tumors

eTUMOUR (http://www.etumour.net/) is acquiring a large database of brain tumor (1)H MR spectra to develop automated pattern recognition methods and decision support system (DSS) for tumor diagnosis. Development of accurate pattern-recognition algorithms requires spectra undistorted by artifacts, low signal-to-noise, or broad lines. eTUMOUR currently uses panels of expert spectroscopists to subjectively grade spectra as being acceptable or unacceptable. Automated quality control (QC) would be more satisfactory for several reasons: 1) to provide a reproducible objective classification of spectrum quality; 2) for use within the future DSS to prevent misdiagnosis due to poor spectrum quality; 3) to rapidly process the very large datasets of 1H spectra being accrued. An automated QC method using independent component analysis for feature extraction with a least-squares support vector machine classifier is presented. Separate training (n=144) and test sets (n=98) of single-voxel spectra from brain tumors and other lesions were acquired at multiple clinical centers with short and long echo times. Pairs of expert spectroscopists classified the test set an average of 85% the same. The automated QC classification agreed with an expert for 87% of test spectra, on average, suggesting the method classifies spectrum quality as accurately as expert spectroscopists.

Application of European protocol in the evaluation of contrast-to-noise ratio and mean glandular dose for two digital mammography systems

The performance of two digital mammography systems, Agfa CR75 and CRMM3 computed radiography (CR) and IMS Giotto MD direct digital radiography (DR), was assessed by applying a method recommended in the European protocol for quality control in mammography screening. The contrast-to-noise ratio (CNR) and mean glandular dose (MGD) values were measured and contrast detail (CD) analysis was performed. The CNRs for system CR were 21.9, 12.9, 9.5, 8.8, 7.4, 5.5 and 4.4 for 2, 3, 4, 4.5, 5, 6 and 7-cm polymenthylmethacrylate (PMMA) thickness, respectively. The respective CNRs for system DR were 10.4, 8.8, 6.3, 7.3, 7.2, 6.4 and 6.54. For the same phantom thickness sequence, the MGDs were 0.7, 1.1, 1.3, 1.6, 1.9, 2.5 and 3.4 mGy for system CR, whereas they were 0.7, 1.2, 1.1, 1.3, 1.8, 3.5 and 3.9 mGy for system DR. The CNR and MGD results satisfactorily correlate with CD analysis results. The MGD values compare well with the values recommended in the European protocol. Despite being simple, CNR and MGD can provide an effective system for performance assessment and constancy checks for related optimisations.

Assessment of performance of a new digital image intensifier fluoroscopy system

The aim of this study is to assess the physical properties of a recently installed digital fluoroscopy unit, Axiom Iconos R200 unit (Siemens, Germany), including image quality and patient dose. Image quality parameters and patient doses were measured at various fields of view (FOV) and frame rates. The entrance surface dose rate (ESDR) was measured using standard 30 x 30 cm2 polymethylmethacrylate (PMMA) phantom with different thicknesses. The ESDR was measured using a 20 cm PMMA and largest FOV ranged from 1.1 to 8.2 mGy min(-1) for different frame rates available. The low-contrast sensitivity varied from 1.8 to 6.6%, as the limiting spatial resolution changes from 1.25 to 2.24 ln mm(-1) for the different magnifications, frame rates and phantom thicknesses. This study shows the weak points of the standard quality control protocols. The additional image quality and dose assessments revealed the existing potential for optimisation of the system.

EU Forum: The CREATE Project: development of certified reference materials for allergenic products and validation of methods for their quantification

Allergen extracts have been used for diagnosis and treatment of allergy for around 100 years. During the second half of 20th century, the notion increasingly gained foothold that accurate standardization of such extracts is of great importance for improvement of their quality. As a consequence, manufacturers have implemented extensive protocols for standardization and quality control. These protocols have overall IgE-binding potencies as their focus. Unfortunately, each company is using their own in-house reference materials and their own unique units to express potencies. This does not facilitate comparison of different products. During the last decades, most major allergens of relevant allergen sources have been identified and it has been established that effective immunotherapy requires certain minimum quantities of these allergens to be present in the administered maintenance dose. Therefore, the idea developed to introduce major allergens measurements into standardization protocols. Such protocols based on mass units of major allergen, quantify the active ingredients of the treatment and will at the same time allow comparison of competitor products. In 2001, an EU funded project, the CREATE project, was started to support introduction of major allergen based standardization. The aim of the project was to evaluate the use of recombinant allergens as reference materials and of ELISA assays for major allergen measurements. This paper gives an overview of the achievements of the CREATE project.

Results of a two-year quality control program for a helical tomotherapy unit

Background and purpose Image-guided helical tomotherapy (HT) is a new modality for delivering intensity modulated radiation therapy (IMRT) with helical irradiation: the slip ring continuously rotates while the couch moves into the bore. The radiation source (Linac, 6 MV) is collimated into a fan beam and modulated by means of a binary multileaf collimator (MLC). A xenon detector array, opposite the radiation source, allows a megavoltage-CT (MVCT) acquisition of patient images for set-up verification. The aim of this paper is to report the results of a two-year quality control (QC) program for the physical and dosimetric characterization of an HT unit installed at our Institute and clinically activated in November 2004, in order to monitor and verify the stability and the reliability of this promising radiation treatment unit. Materials and methods Conventional Linac acceptance protocols (ATP) and QC protocols were adapted to HT with the addition of specific items reflecting important differences between the two irradiation modalities. QC tests can be summarized as: (a) mechanical and geometrical characterization of the system’s components: evaluation of alignment among radiation source–gantry rotation plan–jaws–MLC–MVCT; (b) treatment beam configuration in static condition: depth dose curves (PDD) and profiles, output factors, output reproducibility and linearity; (c) dynamic component characterization: accuracy and reproducibility of MLC positioning; rotational output reproducibility and linearity, leaf latency, couch movement constancy; (d) gantry–couch and MLC–gantry synchronization; and (e) MVCT image quality. Peculiar periodicity specific tolerance and action levels were defined. Ionization chambers (Exradin A1SL 0.056 cc), films (XOmat-V/EDR2), water and solid water phantoms were used to perform quality assurance measurements. Results Over a two-year period the final average output variation after possible beam output adjustment was −0.2 ± 1% for the static condition and equal to 0 ± 1% for the rotational condition: around 98% of the collected output data was within the action level compared to 94% if no beam output adjustment was considered. An average energy variation of −0.4 ± 0.4% was found. The daily absolute dose verification of IMRT plans showed a dose reproducibility of −0.5 ± 1.2% and −0.4 ± 2.2%, for low and high dose gradient regions, respectively. Source–jaws–MLC and MVCT alignment results and jaw and leaf positioning accuracy were ⩽±1 mm. Couch–gantry–MLC synchrony tests showed good stability level (⩽±2 mm). Conclusions QC results indicated good reproducibility of all HT mechanical–dosimetric performance.

Performance of medical radiographic X-ray systems in Greece for the time period 1998–2004

This study presents the results of the on-site inspections performed by the Greek Atomic Energy Commission (GAEC) on conventional X-ray systems, both in public and private medical radiology departments. A part of the inspection concerns the assessment of important radiographic parameters obtained according to a specified quality control protocol and the comparison of the measured parameter values with the corresponding acceptance limits. A total number of 1011 radiographic systems were inspected by the GAEC during the period 1998–2004, with 63.4% of them being privately owned. Analysis of 8 different operational parameters is carried out providing information on the overall performance, as well as on each parameter of the inspected X-ray systems. Tube voltage reproducibility values show the highest percentage of acceptability (98.9%, 99.5% for private and public owned radiographic systems respectively), while linearity of radiation output for private systems (72.5%) and time accuracy for public ones (72.7%) show the worst results. The comparison of the results for the private sector to those of a similar study carried out during the period 1995–1997 indicates a substantial improvement in X-ray systems performance. Higher level of improvement shows exposure time accuracy (12.2% percentile increase) and linearity of radiation output (12.5% percentile increase). Nevertheless, the situation can be further optimized if maintenance and quality control of the radiographic systems are carried out on a more regular basis.

Noninvasive Estimation of Black Bear Abundance Incorporating Genotyping Errors and Harvested Bear

ABSTRACT Estimating black bear (Ursus americanus) population size is a difficult but important requirement when justifying harvest quotas and managing populations. Advancements in genetic techniques provide a means to identify individual bears using DNA contained in tissue and hair samples, thereby permitting estimates of population abundance based on established mark‐capture‐recapture methodology. We expand on previous noninvasive population‐estimation work by geographically extending sampling areas (36,848 km2) to include the entire Northern Lower Peninsula (NLP) of Michigan, USA. We selected sampling locations randomly within biologically relevant bear habitat and used barbed wire hair snares to collect hair samples. Unlike previous noninvasive studies, we used tissue samples from harvested bears as an additional sampling occasion to increase recapture probabilities. We developed subsampling protocols to account for both spatial and temporal variance in sample distribution and variation in sample quality using recently published quality control protocols using 5 microsatellite loci. We quantified genotyping errors using samples from harvested bears and estimated abundance using statistical models that accounted for genotyping error. We estimated the population of yearling and adult black bears in the NLP to be 1,882 bears (95% CI = 1,389‐2,551 bears). The derived population estimate with a 15% coefficient of variation was used by wildlife managers to examine the sustainability of harvest over a large geographic area.

Evaluation of the technical status of radiotherapy simulators involved in clinical trials

Summary Background Radiotherapy simulators play an important role in the preparation of radiation treatment. Their mechanical and geometrical parameters have to be identical with those of the treatment machines. Therefore, quality control protocols for the simulators should be comprehensive and the tolerance limits as high as those for treatment machines. Aim Evaluation of the technical status of radiotherapy simulators involved in clinical trials. Materials/Methods In this paper, results of quality control tests conducted in 12 Polish radiotherapy centres are presented. The tests were carried out within the framework of Polish research project KBN No. 6 P05C 032 20. 12 radiotherapy simulators installed in Polish radiotherapy centres were thoroughly tested. In order to control technical conditions of the simulators, a set of 24 tests was elaborated. The tests were divided into six thematic groups. The detailed range of the parameters controlled and the accepted ranges of tolerance limits are given. The values of tolerance limits are based on data found in the available literature. Results The control of 12 simulators revealed the violation of accepted tolerance limits for 13 out of 24 controlled parameters. The most frequent violations of accepted tolerance limits occurred in the case of geometrical parameters of light simulation and mechanical parameters of the couch, both very important for the accuracy of the simulation process. For 2 simulators almost 30% of controlled parameters were outside the tolerance limits. Conclusions The control of radiotherapy simulators undertaken within the framework of the clinical trial revealed that in the majority of cases the simulators were in good technical condition. In 2 cases almost 30% of controlled parameters were outside the tolerance limits. In such cases the manufacturers' service should be called urgently for necessary repairs and regulations. After repeated quality control tests a decision should be taken regarding the accepted range of operations which could be used in clinical practice. A QA and QC system for radiotherapy simulators should be introduced in each radiotherapy centre.

Image quality evaluation and patient dose assessment of medical fluoroscopic X-ray systems: a national study

This study presents the results from a survey conducted by the Greek Atomic Energy Commission (GAEC), during the period 1998-2003, in 530 public and private owned fluoroscopic X-ray systems in Greece. Certain operational parameters for conventional and remote control systems were assessed, according to a quality control protocol developed by GAEC on the basis of the current literature. Public (91.5%) and private (81.5%) owned fluoroscopic units exhibit high-contrast resolution values over 1 lp mm(-1). Moreover, 88.5 and 87.1% of the fluoroscopic units installed in the public and private sector, respectively, present Maximum Patient Entrance Kerma Rate values lower than 100 mGy min(-1). Additionally, 68.3% of the units assessed were found to perform within the acceptance limits. Finally, the third quartile of the Entrance Surface Dose Rate distribution was estimated according to the Dose Reference Level definition and found equal to 35 mGy min(-1).

Test–Retest Reliability of Self-Reported Reproductive and Lifestyle Data in the Context of a German Case–Control Study on Breast Cancer and Postmenopausal Hormone Therapy

Studies using survey questionnaires to collect epidemiologic data rely on the accuracy of participants' self-reporting. As part of the quality control protocol for a large population-based case-control study of the association between postmenopausal hormone therapy (HT) and breast cancer in German women (the Mammakarzinom-Risikofaktoren-Erhebung [MARIE] study), the authors used test-retest to evaluate the reliability of women's self-reporting of a number of putative breast cancer risk factors, including HT, reproductive history, family history, and lifestyle. Of those women interviewed between November 2002 and July 2003, 62 cases and 61 controls were re-interviewed an average of 10 months later, using a shortened version of the original study questionnaire. Agreement between the first and second interviews was assessed using Cohen's kappa and proportion of agreement. There was very good overall agreement between the two questionnaires for HT ever/never use (kappa = 0.90), type of therapy (kappa = 0.83), and form of application (kappa = 0.73) and good agreement for duration of use (kappa = 0.60). Agreement for other factors ranged from kappa = 1.00 for age at first birth to kappa = 0.43 for weekend bicycle riding. Agreement was nondifferential by disease status. These findings indicate that the MARIE survey instrument was of good quality and had a low likelihood of misclassification.

Preparation and pre-vivo evaluation of no-carrier-added, carrier-added and cross-complexed [ 68Ga]-EDTMP formulations

Purpose The present study aimed to develop convenient preparation and quality control protocols for [ 68Ga]-EDTMP, a potential radiotracer for skeletal PET imaging. Furthermore, bone binding characteristics with special focus on the influence of carrier addition were evaluated. Methods No-carrier-added (nca), carrier-added and novel cross-complexed [ 68Ga]-EDTMP formulations were prepared using [ 68Ga]-gallium chloride and a commercial EDTMP kit. Respective bone binding characteristics were determined on the basis of an established in-vitro method using hydroxyapatite and human bone powders as binding matrices. Results Pre-vivo evaluation of nca [ 68Ga]-EDTMP yielded irreversible binding on the mineral bone phase characterised by fast binding kinetics. Generally, nca [ 68Ga]-EDTMP showed low uptake values comparable to nca [ 99mTc]-EDTMP. Interestingly, the bone binding affinity of [ 68Ga]-EDTMP could be increased by the addition of carriers, presumably by changing the complex structure. Conclusions This fast and reliable preparation protocol could enable small PET facilities without onsite cyclotron to perform PET bone scans. A comparison of all cross-complexed [ 68Ga]-EDTMP preparations further strengthens the recently presented “foreign carrier theory”, which highlights carrier addition as a factor strongly affecting bone uptake of radiolabelled polyphosphonates. The clinical applicability of [ 68Ga]-EDTMP – particularly with respect to lesion specificity and sensitivity – should be clarified in forthcoming in-vivo studies.

Thermodynamic Properties of Trace Water Vapor in High Purity Hydrogen Bromide used for Semiconductor Processing

The distribution of water between gas and liquid phases was investigated for high purity HBr cylinders, and standard enthalpy of vaporization and Henry's law constant for trace amount of water in HBr were extracted. In the 3-32 {degree sign} C temperature range, the water vapor concentration in the gas phase of a cylinder is a function of cylinder temperature and the enthalpies of vaporization of water and HBr. The standard enthalpy of vaporization for trace amount of H2O in HBr was found to be 58.5 kJ/mol. The temperature dependent Henry's law constant can be expressed as: ln K(T) = -7031.44/T + 22.38. Using the thermodynamic parameters found, water vapor concentration measured for gas-phase HBr from cylinders at various temperatures can be normalized to corresponding levels at a chosen standard temperature, e.g. 21{degree sign}C. This is very important in establishing meaningful water vapor specifications, and trustworthy quality control protocols for high purity HBr gas.

Pipelines, Robots, Crystals and Biology: What Use High Throughput Solving Structures of Challenging Targets?

With recent advances in the technology and software underlying crystallographic structure solution, demands on both output and functional significance of X-ray structures are soaring. To achieve the required speed and quality also with ever larger and more difficult targets, combining HTP screening methods (robotics based or not) adopted from structural genomics initiatives with thorough expertise and dedicated characterization effort for each individual target is almost a must. I present concepts, practical considerations, and experiences on implementing an HTP technology platform for structural and functional studies on complexes, membrane proteins and other challenging targets. Emphasis lies on the environment of small academic groups engaged exclusively in hypothesis driven projects focused on specific biological systems. Suitability of given HTP protocols for particular target classes, benchmarking and quality control for procedures, and project management issues at the interface between extensive, broad parameter screening and intensive individual target work required by non-SG amenable targets are discussed.

Survey of computed tomography scanners in Taiwan: Dose descriptors, dose guidance levels, and effective doses

The IAEA and the ICRP recommended dose guidance levels for the most frequent computed tomography (CT) examinations to promote strategies for the optimization of radiation dose to CT patients. A national survey, including on-site measurements and questionnaires, was conducted in Taiwan in order to establish dose guidance levels and evaluate effective doses for CT. The beam quality and output and the phantom doses were measured for nine representative CT scanners. Questionnaire forms were completed by respondents from facilities of 146 CT scanners out of 285 total scanners. Information on patient, procedure, scanner, and technique for the head and body examinations was provided. The weighted computed tomography dose index (CTDI(w)), the dose length product (DLP), organ doses and effective dose were calculated using measured data, questionnaire information and Monte Carlo simulation results. A cost-effective analysis was applied to derive the dose guidance levels on CTDI(w) and DLP for several CT examinations. The mean effective dose +/- standard deviation distributes from 1.6 +/- 0.9 mSv for the routine head examination to 13 +/- 11 mSv for the examination of liver, spleen, and pancreas. The surveyed results and the dose guidance levels were provided to the national authorities to develop quality control standards and protocols for CT examinations.

Qualitative application based on IR spectroscopy for bone sample quality control in radiocarbon dating

Bone samples suffer from contamination and deterioration, depending on their conservation state and previous restoration and consolidation processes. The sample preparation laboratory of the CEDAD (Center for Dating and Diagnostics) of the University of Lecce is developing a quality control protocol for bone samples based on Fourier transform infrared (FTIR) spectroscopy to identify the presence of collagen in bone samples and to assess its quality. FTIR measurements were carried out on collagen extracted from many ancient samples dated at CEDAD. Efforts to shift the FTIR quality control test from the filtration step to a check-in treatment are proceeding to optimize the time for preparation and to reduce the overall turnaround time. A standard fast demineralization treatment was set up and applied to a variety of ancient samples of different origin and age.

GC-MS and HPLC-MS analysis of bioactive pharmaceuticals and personal-care products in environmental matrices

We review analytical methods published between January 2001 and January 2007 using either gas chromatography (GC) or high-performance liquid chromatography (HPLC) separations and mass spectrometric (MS) detection technologies for the analysis of bioactive pharmaceuticals and personal-care products (PPCPs) in environmental matrices. We emphasize sample preparation, the pros and cons of available MS techniques, the benefits of using quality control and quality assurance (QC/QA) protocols during routine analysis, and the difficulties associated with the matrix effect in the electrospray ionization (ESI) source. We discuss the need for a concerted approach to determine numerical values associated with limits of detection in this emerging area of environmental analysis, along with the use of QC/QA samples and low-level data qualifiers with recommended solutions.

DEVELOPMENT OF QUALITY CONTROL PROCEDURES FOR MASS PRODUCED AND RELEASED BACTROCERA PHILIPPINENSIS (DIPTERA: TEPHRITIDAE) FOR STERILE INSECT TECHNIQUE PROGRAMS

Quality control procedures for Bactrocera philippinensis Drew & Hancock 1994 (Diptera: Tephritidae) used in sterile insect technique (SIT) programs were established in the mass rearing facility at the Philippine Nuclear Research Institute. Basic studies on pupal irradiation, holding/packaging systems, shipping procedures, longevity, sterility studies, and pupal eye color determination in relation to physiological development at different temperature regimes were investigated. These studies will provide baseline data for the development of quality control protocols for an expansion of B. philippinensis field programs with an SIT component in the future.

Development of quality control standards for radiation therapy equipment in Canada

Among the essential components of a comprehensive quality assurance program in radiotherapy are the quality control protocols to be used on the equipment and, in particular, the performance objectives and criteria. In the present work, we describe the development of a suite of quality control documents for use across Canada. Following a generic format, we are generating concise, clear standards for the most commonly used equipment in radiotherapy, with the emphasis on performance measures. The final standards of performance are confirmed following cross‐country consultation facilitated by the availability of draft documents on the Canadian Medical Physics web site.PACS number: 87.53.Xd