Consensus Dataset Research Articles

Dosimetric characterization of the 60Co BEBIG Co0.A86 high dose rate brachytherapy source using PENELOPE

60Co sources are being used as an alternative to 192Ir sources in high dose rate brachytherapy treatments. In a recent document from AAPM and ESTRO, a consensus dataset for the 60Co BEBIG (model Co0.A86) high dose rate source was prepared by using results taken from different publications due to discrepancies observed among them. The aim of the present work is to provide a new calculation of the dosimetric characteristics of that 60Co source according to the recommendations of the AAPM and ESTRO report. Radial dose function, anisotropy function, air-kerma strength, dose rate constant and absorbed dose rate in water have been calculated and compared to the results of previous works. Simulations using the two different geometries considered by other authors have been carried out and the effect of the cable density and length has been studied.

A global 1‐km consensus land‐cover product for biodiversity and ecosystem modelling

AbstractAimFor many applications in biodiversity and ecology, existing remote sensing‐derived land‐cover products have limitations due to among‐product inconsistency and their typically non‐continuous nature. Here we aim to help address these shortcomings by generating a 1‐km resolution global product that provides scale‐integrated and accuracy‐weighted consensus land‐cover information on an approximately continuous scale.LocationGlobal.MethodsUsing a generalized classification scheme and an accuracy‐based integration approach, we integrated four global land‐cover products. We evaluated the performance of this product compared with inputs for estimating subpixel 30‐m resolution land cover. We also compared the accuracy of deductive and inductive species distribution models built with the different products for modelling the continental distributions of six avian habitat specialists.ResultsOur product offers accuracy‐weighted consensus information on the prevalence of 12 land‐cover classes within every nominal 1‐km pixel across the globe (except for Antarctica). Compared with the four base products, it better captures the land‐cover information contained in the fine‐grain validation data for all classes combined and for most individual classes. It also has the highest sensitivity and overall accuracy for detecting the presence of every fine‐grain land‐cover class. Both deductive and inductive models built with the consensus dataset have the highest or second highest accuracy for modelling bird species distributions.Main conclusionsOur consensus product integrates the four base products and successfully maximizes accuracy and reduces errors of omission. Specifically, the consensus product reduces limitations caused by misclassifications, false absence rates and the categorical format of existing land‐cover products. Consequently, it surpasses single base products in the ability to capture subpixel land‐cover information and the utility for modelling species distributions. Both the presented methodology and the consensus product have multiple applications in biodiversity research and for understanding and modelling of global terrestrial ecosystems.

Developing a national database for metastatic colorectal cancer management: perspectives and challenges

The changing treatment landscape for metastatic colorectal cancer creates multiple potential treatment strategies. An Australian-centric database capturing comprehensive information across a range of treatment locations would create a valuable resource enabling multiple important research questions to be addressed. To establish a collection of a consensus dataset capturing treatment and outcomes at multiple public and private hospitals across Australia. An electronic database was developed by a panel of clinicians, to capture an agreed dataset for patients with newly diagnosed metastatic colorectal cancer. Of particular interest were clinician decision-making, the impact of comorbidities and the frequency of major adverse events. Since July 2009, data collection has been established at six public and eight private hospitals across three Australian states and territories. Successful linkage and analysis, with support from BioGrid Australia, of selected data on the initial 864 patients demonstrates that data can be captured from diverse sites, including public and private practice, that multiple factors impact on treatment delivered and outcomes achieved and that comprehensive data on rare but important adverse events can be captured. As a clinical research tool, the project has been highly successful, generating multiple presentations at national and international conferences related to a diverse range of research questions. Multistate, project-specific data collection involving large numbers of patients is achievable. Providing invaluable insight into the routine clinical management of metastatic colorectal cancer in the era of targeted therapies, this also creates a significant resource for research, including many questions not being addressed by clinical trials.

EGSnrc Monte Carlo-aided dosimetric studies of the new BEBIG 60 Co HDR brachytherapy source

PurposeThe purpose of this study is to obtain the dosimetric parameters of the new BEBIG 60Co brachytherapy source following by TG-43U1 recommendation with appropriate electron cutoff energy (0.521 MeV).Material and methodsThe new BEBIG 60Co brachytherapy source is used to calculate the TG-43U1 parameters. EGSnrc-based Monte Carlo simulation code has been used to calculate the radial dose functions and anisotropy functions. 2D dose rate table is obtained with Cartesian coordinate system for surrounding the source.ResultsThe radial dose functions are calculated for the distance of 0.06 cm to 100 cm from the source center with different cutoff energies and compared. The anisotropy functions values are calculated with the range of 1° to 179°, and apart from 0.2 cm to 20 cm of radial distances. The along-away dose rate data are calculated for quality assurance purposes. The calculated values are compared with the consensus data set and previous published results.ConclusionsThe radial dose function values from 0.06 cm to 0.16 cm are low, and these values gradually increased up to 0.3 cm radial distance. The radial dose function values are compared with the values of consensus data set using EGSnrc code system, and it is in good agreement with the published data range. The data for < 0.1 cm is not available in consensus data set, and extrapolated value is included for 0 distances which is the same as the value of 0.1 cm. In this study, the obtained values are strictly fall-off to < 0.1 cm distances. Good agreement with the published data was observed, except the values less than 40° angle at 0.5 cm distance for anisotropy function values.

Intercomparison and assessment of turbulent and physiological exchange parameters of grassland

Abstract. Commonly, the micrometeorological parameters that underline the calculations of surface atmosphere exchange fluxes (e.g. friction velocity and sensible heat flux) and parameters used to model exchange fluxes with SVAT-type parameterisations (e.g. latent heat flux and canopy temperature) are measured with a single set of instrumentation and are analysed with a single methodology. This paper evaluates uncertainties in these measurements with a single instrument, by comparing the independent results from nine different institutes during the international GRAMINAE integrated field experiment over agricultural grassland near Braunschweig, Lower Saxony, Germany. The paper discusses uncertainties in measuring friction velocity, sensible and latent heat fluxes, canopy temperature and investigates the energy balance closure at this site. Although individual 15-min flux calculations show a large variability between the instruments, when averaged over the campaign, fluxes agree within 2% for momentum and 11% for sensible heat. However, the spread in estimates of latent heat flux (λE) is larger, with standard deviations of averages of 18%. The dataset averaged over the different instruments fails to close the energy budget by 20%, significantly larger than the uncertainties in the individual flux corrections. However, if the largest individual turbulent flux estimates are considered, energy closure can be achieved, indicating that the closure gap is within the spread of the measurements. The uncertainty in λE feeds results in an uncertainty in the bulk stomatal resistance, which further adds to the uncertainties in the estimation of the canopy temperature that controls the exchange. The paper demonstrated how a consensus dataset was derived, which is used by the individual investigators to calculate fluxes and drive their models.

Military Return to Duty and Civilian Return to Work Factors Following Burns With Focus on the Hand And Literature Review

Functional recovery and outcome from severe burns is oftentimes judged by the time required for a person to return to work (RTW) in civilian life. The equivalent in military terms is return to active duty. Many factors have been described in the literature as associated with this outcome. Hand function, in particular, is thought to have a great influence on the resumption of preburn activities. The purpose of this investigation was to compare factors associated with civilian RTW with combat injured military personnel. A review of the literature was performed to assimilate the many factors reported as involved with RTW or duty. Additionally, a focus on the influence of hand burns is included. Thirty-four different parameters influencing RTW have been reported inconsistently in the literature. In a military population of combat burns, TBSA burn, length of hospitalization and intensive care and inhalation injury were found as the most significant factors in determining return to duty status. In previous RTW investigations of civilian populations, there exists a scatter of factors reported to influence patient disposition with a mixture of conflicting results. In neither military nor civilian populations was the presence of a hand burn found as a dominant factor. Variety in patient information collected and statistical approaches used to analyze this information were found to influence the results and deter comparisons between patient populations. There is a need for a consensus data set and corresponding statistical approach used to evaluate RTW and duty outcomes after burn injury.

Application of proteomics to hematology: the revolution is starting

and for a current consensus dataset of1200 proteins. However, to date, this flood of data hasresulted in little gain for hematological sci-ence and clinical practice. The reasons forthis dead valley between basic research (thebrute-force acquisition of proteomic data)and translational medicine lie in the diffi-culty of extracting valuable biologicalinformation from the data. First, the way asample is preprocessed may have a pro-found influence on the observed profile ofpeptides and proteins; a difficulty that hasnow been relatively well documented, espe-cially from the biomarker discovery field.For example, the use of protease inhibitorsresults in a dramatically different proteinpattern (compared with noninhibited one),as demonstrated by 2D gel electrophoresis(GE): when protease inhibitors are omit-ted, considerable amounts of low-molecu-lar-weight proteolytic fragments appearduring sample processing

Interobserver variability of size and density measurements on CT in patients with metastatic GISTS on imatinib mesylate (IM)

10563 Background: Response assessment to IM in GISTs by Choi criteria depends on size/density measurements. These may be subject to interobserver variability. We evaluated the interobserver variability of size (longest dimension in mm) and density (mean Hounsfield units HFU) in patients (pts) with metastatic GISTs on IM. Methods: 27 lesions (Primary=3, Liver=7, Peritoneal=17) from 8 GIST pts on IM were included in the study. Contrast triple phase CT (Siemens multi slice CT, IV Niopam, GE PACS system) was performed at baseline and at 3 monthly intervals. In 2007, the authors (VRB, NC, SF & PM) evaluated the longest dimension and the mean density in HFU of all lesions and reached a consensus value for each lesion at baseline and at 3 months on IM. VRB and SF repeated the exercise independently in 2008. The values for longest dimension and mean density at baseline and at 3 months on IM were compared with the consensus dataset recorded earlier by the authors. Results: 2 datasets generated by VRB & SF were evaluated against the consensus dataset from 2007. At baseline, 81% of the values for size and 88% of the values for density (as measured by VRB & SF) were within 10% of the consensus values. At 3 months, these figures were 92% for size and 81% for density. Conclusions: We believe that both size and density measurements are reproducible and the interobserver variation seems to be acceptable. However, we recommend that these evaluations are carried out by radiologists with experience in assessing response to targeted therapy. No significant financial relationships to disclose.

CATHEDRAL: A Fast and Effective Algorithm to Predict Folds and Domain Boundaries from Multidomain Protein Structures

We present CATHEDRAL, an iterative protocol for determining the location of previously observed protein folds in novel multidomain protein structures. CATHEDRAL builds on the features of a fast secondary-structure–based method (using graph theory) to locate known folds within a multidomain context and a residue-based, double-dynamic programming algorithm, which is used to align members of the target fold groups against the query protein structure to identify the closest relative and assign domain boundaries. To increase the fidelity of the assignments, a support vector machine is used to provide an optimal scoring scheme. Once a domain is verified, it is excised, and the search protocol is repeated in an iterative fashion until all recognisable domains have been identified. We have performed an initial benchmark of CATHEDRAL against other publicly available structure comparison methods using a consensus dataset of domains derived from the CATH and SCOP domain classifications. CATHEDRAL shows superior performance in fold recognition and alignment accuracy when compared with many equivalent methods. If a novel multidomain structure contains a known fold, CATHEDRAL will locate it in 90% of cases, with <1% false positives. For nearly 80% of assigned domains in a manually validated test set, the boundaries were correctly delineated within a tolerance of ten residues. For the remaining cases, previously classified domains were very remotely related to the query chain so that embellishments to the core of the fold caused significant differences in domain sizes and manual refinement of the boundaries was necessary. To put this performance in context, a well-established sequence method based on hidden Markov models was only able to detect 65% of domains, with 33% of the subsequent boundaries assigned within ten residues. Since, on average, 50% of newly determined protein structures contain more than one domain unit, and typically 90% or more of these domains are already classified in CATH, CATHEDRAL will considerably facilitate the automation of protein structure classification.

Dose calculation formalisms and consensus dosimetry parameters for intravascular brachytherapy dosimetry: Recommendations of the AAPM Therapy Physics Committee Task Group No. 149

Since the publication of AAPM Task Group 60 report in 1999, a considerable amount of dosimetry data for the three coronary brachytherapy systems in use in the United States has been reported. A subgroup, Task Group 149, of the AAPM working group on Special Brachytherapy Modalities (Bruce Thomadsen, Chair) was charged to develop recommendations for dose calculation formalisms and the related consensus dosimetry parameters. The recommendations of this group are presented here. For the Cordis 192Ir and Novoste 90Sr/90Y systems, the original TG-43 formalism in spherical coordinates should be used along with the consensus values of the dose rate constant, geometry function, radial dose function, and anisotropy function for the single seeds. Contributions from the single seeds should be added linearly for the calculation of dose distributions from a source train. For the Guidant 32P wire system, the modified TG-43 formalism in cylindrical coordinates along with the recommended data for the 20 and 27 mm wires should be used. Data tables for the 6, 10, 14, 18, and 22 seed trains of the Cordis system, 30, 40, and 60 mm seed trains of the Novoste system, and the 20 and 27 mm wires of the Guidant system are presented along with our rationale and methodology for selecting the consensus data. Briefly, all available datasets were compared with each other and the consensus dataset was either an average of available data or the one obtained from the most densely populated study; in most cases this was a Monte Carlo calculation.

Improving the Quality of Cancer Registry Data on Adult Haematopoietic Neoplasms: Impact of Engaging Clinicians.

Haematological malignancies (HM) accounts for 7% of all cancers in England (DoH, 2003). However, concerns have been expressed regarding the quality of information from cancer registries (DoH, 2000, Haward, 2003) which sheds doubt on the validity of the data. Several initiatives have been undertaken to improve the quality of data (Cartwright et al., 1990, 1997, Clough et al., 1996, Taylor et al., 1998, Maynadie et al., 1996, Ong et al., 1997). These initiatives have been restricted in the range of diagnoses or have operated independently of national cancer registries (Phekoo et al., 2002). No studies have assessed the impact of incidence on survival rates. We present results of a collaboration designed to improve the quality of data and assess the impact on incidence and survival.A consensus dataset and database of HM was developed between the Thames Cancer Registry (TCR) and clinicians between 1999 and 2000 in South Thames (adult population 5.4 million). Clinicians identified and confirmed the diagnosis of patients whilst diagnostic data were collected by a dedicated team of data collectors. Clinicians validated their cases bi-annually. Incidence and survival of the study population for the period 1999–2000 following the collaboration were compared with the same population over the period 1994–1996 prior to the collaboration and with a control population (North Thames area, adult population 5.5 million), where TCR collected data but without any clinical collaboration, for the period 1999–2000.Statistical analyses: the statistical significance of the standardized rate ratio (SRR) was evaluated using the method of Jensen et al., (1991). The Kaplan-Meier survival curves were compared using the log-rank test.For the period 1994–1996 there were no differences in the SRR or survival estimates in any disorders between North and South Thames. A 43% increase in incidence occurred between 1994–1996 and 1999–2000 in South Thames compared to only 5% in North Thames over the same periods, mainly for CLL, MDS, PV, PT, IMF, MGUS and WM. Table I shows a statistically significant difference in the SRR between the North and South Thames during the period 1999–2000 for five conditions: CLL, MDS, PV, PT and WM. Three year survival for patients diagnosed between 1999 and 2000 were higher in South Thames than North Thames in four conditions: CLL (71% vs. 49%, p = 0.001), CML (50% vs. 30%, p = 0.001), MDS (45% vs. 27%, p <0.001) and MM (39% vs. 28%, p <0.001). No significant difference in incidence or survival were seen for acute leukaemia, NHL or HD.Table 1: Comparison of the age standardized rate between 1994–1996 and 1999–2000 in patients aged 16–85+ years1994–19961999–2000North ThamesSouth ThamesComparisonNorth ThamesSouth ThamesComparisonSubtypesASRASRSRR (95% CI)ASRASRSRR (95% CI)CLL4.284.760.89 (0.89–1.07)3.786.580.57 (0.48–0.67)MDS2.332.151.08 (0.80–1.46)3.485.800.60 (0.50–0.71)PT0.690.910.75 (0.50–1.13)0.482.570.18 (0.13–0.26)PV1.051.060.99 (0.69–1.41)0.721.600.45 (0.31–0.63)WM0.370.371.00 ( 0– 0)0.330.980.33 (0.21–0.53)This study has shown that engaging clinicians have improved case ascertainment and that changes in incidence alone may affect outcome without significant differences in treatment. This study provides a benchmark of incidence and survival in the UK and a model for future collaborations.

Update of AAPM Task Group No. 43 Report: A revised AAPM protocol for brachytherapy dose calculations

Since publication of the American Association of Physicists in Medicine (AAPM) Task Group No. 43 Report in 1995 (TG-43), both the utilization of permanent source implantation and the number of low-energy interstitial brachytherapy source models commercially available have dramatically increased. In addition, the National Institute of Standards and Technology has introduced a new primary standard of air-kerma strength, and the brachytherapy dosimetry literature has grown substantially, documenting both improved dosimetry methodologies and dosimetric characterization of particular source models. In response to these advances, the AAPM Low-energy Interstitial Brachytherapy Dosimetry subcommittee (LIBD) herein presents an update of the TG-43 protocol for calculation of dose-rate distributions around photon-emitting brachytherapy sources. The updated protocol (TG-43U1) includes (a) a revised definition of air-kerma strength; (b) elimination of apparent activity for specification of source strength; (c) elimination of the anisotropy constant in favor of the distance-dependent one-dimensional anisotropy function; (d) guidance on extrapolating tabulated TG-43 parameters to longer and shorter distances; and (e) correction for minor inconsistencies and omissions in the original protocol and its implementation. Among the corrections are consistent guidelines for use of point- and line-source geometry functions. In addition, this report recommends a unified approach to comparing reference dose distributions derived from different investigators to develop a single critically evaluated consensus dataset as well as guidelines for performing and describing future theoretical and experimental single-source dosimetry studies. Finally, the report includes consensus datasets, in the form of dose-rate constants, radial dose functions, and one-dimensional (1D) and two-dimensional (2D) anisotropy functions, for all low-energy brachytherapy source models that met the AAPM dosimetric prerequisites [Med. Phys. 25, 2269 (1998)] as of July 15, 2001. These include the following 125I sources: Amersham Health models 6702 and 6711, Best Medical model 2301, North American Scientific Inc. (NASI) model MED3631-A/M, Bebig/Theragenics model I25.S06, and the Imagyn Medical Technologies Inc. isostar model IS-12501. The 103Pd sources included are the Theragenics Corporation model 200 and NASI model MED3633. The AAPM recommends that the revised dose-calculation protocol and revised source-specific dose-rate distributions be adopted by all end users for clinical treatment planning of low energy brachytherapy interstitial sources. Depending upon the dose-calculation protocol and parameters currently used by individual physicists, adoption of this protocol may result in changes to patient dose calculations. These changes should be carefully evaluated and reviewed with the radiation oncologist preceding implementation of the current protocol.

AN INTRODUCTION TO MEDICAL STATISTICS

<h3>Objectives</h3> This study aimed to develop consensus on an internationally agreed dataset for juvenile dermatomyositis (JDM), designed for clinical use, to enhance collaborative research and allow integration of data between centres. <h3>Methods</h3> A prototype dataset was developed through a formal process that included analysing items within existing databases of patients with idiopathic inflammatory myopathies. This template was used to aid a structured multistage consensus process. Exploiting Delphi methodology, two web-based questionnaires were distributed to healthcare professionals caring for patients with JDM identified through email distribution lists of international paediatric rheumatology and myositis research groups. A separate questionnaire was sent to parents of children with JDM and patients with JDM, identified through established research networks and patient support groups. The results of these parallel processes informed a face-to-face nominal group consensus meeting of international myositis experts, tasked with defining the content of the dataset. This developed dataset was tested in routine clinical practice before review and finalisation. <h3>Results</h3> A dataset containing 123 items was formulated with an accompanying glossary. Demographic and diagnostic data are contained within form A collected at baseline visit only, disease activity measures are included within form B collected at every visit and disease damage items within form C collected at baseline and annual visits thereafter. <h3>Conclusions</h3> Through a robust international process, a consensus dataset for JDM has been formulated that can capture disease activity and damage over time. This dataset can be incorporated into national and international collaborative efforts, including existing clinical research databases.