bluuebunny/crossref_metadata_2025 huggingface dataset:
Bioactive food chemicals and gastrointestinal symptoms: a focus of salicylates
Authors: Malakar Sreepurna
Published: February 2017

Bioactive food chemicals are substances present in food that are capable of interacting with living cells causing changes in physiological functions. Salicylic acid (SA), a plant hormone involved in plant immune response, is one such bioactive food chemical. Aspirin, a commercially available SA, might play beneficial roles in cardiovascular health and colon cancer. It may also cause urticaria, angioedema, asthma, and gastrointestinal symptoms in SA‐sensitive individuals. Dietary SA might exert similar beneficial effects and/or may induce similar symptoms in hypersensitive individuals. Food‐related SA sensitivity in relation to gastrointestinal symptoms is not well documented besides a few self‐reported questionnaires and the knowledge that low doses of aspirin (equivalent of high dietary intake) can cause gastrointestinal injury. The only direct evidence that suggests benefits of reducing dietary SA was reported in asthmatic individuals. Although SA sensitivity in relation to gut symptoms in susceptible individuals is accepted by clinicians, the detection of this disease remains a challenge because of the complicated nature of dietary challenges and the risk of oral aspirin provocation tests in patients with severe hypersensitivity reactions. Given the non‐IgE mediated nature of the disease, in vitro assays like basophil activation may have failed to produce reliable results. However, given the simplicity of this assay, further studies need to be formulated to firmly establish its reliability. Formulation of proper dietary strategies for symptom control is also impossible given the controversial and scant nature of the data on SA content of food. This issue needs to be resolved to formulate proper dietary strategies for effective symptom control.
Coeliac disease in the 21st century: paradigm shifts in the modern age
Authors: Newnham Evan D
Published: February 2017

The epidemiology of coeliac disease (CD) is changing. Presentation of CD with malabsorptive symptoms or malnutrition is now the exception rather than the rule and, it now affects those underweight and overweight equally. In concert with these epidemiological shifts, the incidence of CD is increasing. These changing patterns of disease presentation are challenging traditional management paradigms, and clinicians now need to adapt to these changes and respond to the demands of an increasingly well‐informed consumer population. This article aims to provide historical context to the epidemiological changes in CD, which provides context to direct future research.

Changing definitions and diagnostic paradigms are complicating the management of CD. The gold standard of diagnosis, treatment goals, guidelines for follow‐up, and the role of population screening in CD remain controversial and unresolved. Although the patient population is interested in new treatments for CD and alternatives to a gluten‐free diet, most therapies are not yet widely available or sufficiently researched, and our understanding of the natural history of CD is limited despite a number of retrospective and population‐based studies. The management of asymptomatic CD has only recently been examined despite up to half of patients now presenting with no or minimal symptoms.

There is surprisingly little evidence to resolve many of these issues, and only with robust prospective studies will our understanding of the true natural history of coeliac disease be clarified.
The P2X7 receptor links mechanical strain to cytokine IL‐6 up‐regulation and release in neurons and astrocytes
Authors: Lu Wennan , Albalawi Farraj , Beckel Jonathan M. , Lim Jason C. , Laties Alan M. , Mitchell Claire H.
Published: February 2017

Mechanical strain in neural tissues can lead to the up‐regulation and release of multiple cytokines including interleukin 6 (IL‐6). In the retina, the mechanosensitive release of ATP can autostimulate P2X7 receptors on both retinal ganglion cell neurons and optic nerve head astrocytes. Here, we asked whether the purinergic signaling contributed to the IL‐6 response to increased intraocular pressure (IOP) in vivo, and stretch or swelling in vitro. Rat and mouse eyes were exposed to non‐ischemic elevations in IOP to 50–60 mmHg for 4 h. A PCR array was used to screen cytokine changes, with quantitative (q)PCR used to confirm mRNA elevations and immunoblots used for protein levels. P2X7 antagonist Brilliant Blue G (BBG) and agonist (4‐benzoyl‐benzoyl)‐ATP (BzATP) were injected intravitreally. ELISA was used to quantify IL‐6 release from optic nerve head astrocytes or retinal ganglion cells. Receptor identity was confirmed pharmacologically and in P2X7−/− mice, acute elevation of IOP altered retinal expression of multiple cytokine genes. Elevation of IL‐6 was greatest, with expression of IL1rn, IL24, Tnf, Csf1, and Lif also increased more than twofold, while expression of Tnfsf11, Gdf9, and Tnfsf4 were reduced. qPCR confirmed the rise in IL‐6 and extracellular ATP marker ENTPD1, but not pro‐apoptotic genes. Intravitreal injection of P2X7 receptor antagonist BBG prevented the pressure‐dependent rise in IL‐6 mRNA and protein in the rat retina, while injection of P2X7 receptor agonist BzATP was sufficient to elevate IL‐6 expression. IOP elevation increased IL‐6 in wild‐type but not P2X7R knockout mice. Application of mechanical strain to isolated optic nerve head astrocytes increased IL‐6 levels. This response was mimicked by agonist BzATP, but blocked by antagonists BBG and A839977. Stretch or BzATP led to IL‐6 release from both astrocytes and isolated retinal ganglion cells. The mechanosensitive up‐regulation and release of cytokine IL‐6 from the retina involves the P2X7 receptor, with both astrocytes and neurons contributing to the response.

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Differences in care burden of patients undergoing dialysis in different centres in the netherlands
Authors: de Kleijn Ria , Uyl‐de Groot Carin , Hagen Chris , Diepenbroek Adry , Pasker‐de Jong Pieternel , ter Wee Piet
Published: February 2017

Background

A classification model was developed to simplify planning of personnel at dialysis centres. This model predicted the care burden based on dialysis characteristics. However, patient characteristics and different dialysis centre categories might also influence the amount of care time required.

Objective

To determine if there is a difference in care burden between different categories of dialysis centres and if specific patient characteristics predict nursing time needed for patient treatment.

Design

An observational study.

Participants

Two hundred and forty‐two patients from 12 dialysis centres.

Measurements

In 12 dialysis centres, nurses filled out the classification list per patient and completed a form with patient characteristics. Nephrologists filled out the Charlson Comorbidity Index. Independent observers clocked the time nurses spent on separate steps of the dialysis for each patient. Dialysis centres were categorised into four types. Data were analysed using regression models.

Results

In contrast to other dialysis centres, academic centres needed 14 minutes more care time per patient per dialysis treatment than predicted in the classification model. No patient characteristics were found that influenced this difference. The only patient characteristic that predicted the time required was gender, with more time required to treat women. Gender did not affect the difference between measured and predicted care time.

Conclusion

Differences in care burden were observed between academic and other centres, with more time required for treatment in academic centres. Contribution of patient characteristics to the time difference was minimal. The only patient characteristics that predicted care time were previous transplantation, which reduced the time required, and gender, with women requiring more care time.
Quantifying Aquaculture‐derived Dissolved Organic Matter in the Mesocosms of Sanggou Bay Using Excitation‐emission Matrix Spectra and Parallel Factor Analysis
Authors: Wang Xiaona , Wu Ying , Jiang Zengjie , Ma Qianqian , Zhang Jing , Liu Sumei
Published: February 2017

The cycling and fate of dissolved organic matter (DOM) in aquaculture systems are unique. Sanggou Bay, an aquaculture‐dominated system in China, was chosen to characterize the composition of DOM based on optical properties. Field incubation experiments of eight mesocosms containing various aquaculture organisms were conducted in July 2013 to explore the impact of aquaculture organisms on the DOM composition. Dissolved organic carbon (DOC) showed an increasing trend, especially in integrated mesocosms, suggesting the accumulation of DOM in the aquaculture ecosystem. The DOC concentration was positively correlated with a280 (P < 0.01) rather than a355, demonstrating that a280 should be applied in the quantitative prediction of DOC in aquaculture systems. Parallel factor analysis was applied to identify the components of the excitation‐emission matrix spectra. Two humic‐like components and two protein‐like components were identified. The significant correlation between the wet weights of the organisms and the humic‐like component contents (P < 0.01) indicated that seaweeds and bivalves play important roles in the production of humic‐like matter. The variation of protein‐like materials was caused by the growth of aquaculture organisms and the decay of phytoplankton. The amount of bioavailable DOC (BDOC) derived from phytoplankton and organisms was estimated; bivalve organisms excreted more BDOC than did seaweeds. BDOC was significantly correlated with the protein‐like components (P < 0.05) in the microbial incubation experiment.
Distribution and status of the declining garden dormouseEliomys quercinus
Authors: Bertolino Sandro
Published: February 2017

The garden dormouseEliomys quercinus, a native European rodent species, suffered a significant contraction in its geographical range in the last few decades. The species has disappeared from large parts of central and eastern Europe and is considered extinct in some countries.

I reviewed the information available on the occurrence and distribution of the species in 26 countries where it was previously reported. Present and past introductions outside its native range were also summarised.

The garden dormouse is considered extinct in Lithuania, Finland, and Slovakia, probably extinct in Belarus, and present with single populations in the Netherlands, Poland, and Slovenia; in Slovakia, however, monitoring is necessary to verify recent records. The species is rare and localised in Austria, Ukraine, Romania, and Croatia and is in regression in Germany, Flanders (Belgium), Czech Republic, Latvia, and Estonia. In 2015, the garden dormouse occupied 49% of its 1978 geographical range and 67% of its 2008 range.

South‐western Europe is the stronghold of the species; it is still common in large parts of Portugal, Spain, France, and Italy. However, there are indications that also in these countries, the species is locally declining.

Present knowledge cannot explain the extensive regression of the garden dormouse's range in central and eastern Europe. Probably, it is the result of the interaction of different factors, acting locally and at a large scale, and related to specific ecological requirements of the species.

There is a strong need for research to determine the reasons for the dramatic population and geographical range contraction of the garden dormouse. Meanwhile, it is important to monitor this species and to identify appropriate conservation measures.
Petrology, mineralogy, porosity, and cosmic‐ray exposure history of Huaxi ordinary chondrite
Authors: Li Shijie , Wang Shijie , Leya Ingo , Li Yang , Li Xiongyao , Smith Thomas
Published: February 2017

A meteorite fall was heard and collected on July 13, 2010 at about 18:00 (local time) in the Shibanjing village of the Huaxi district of Guiyang, Guizhou province, China. The total mass of the fall is estimated to be at least 1.6 kg; some fragments are missing. The meteorite consists mainly of olivine, low‐Ca pyroxene, high‐Ca pyroxene, plagioclase, kamacite, taenite, and troilite. Minor phases include chromite and apatite. Various textural types of chondrules exist in this meteorite: most chondrule textures can be easily defined. The grain sizes of secondary plagioclase in this meteorite range from 2 to 50 μm. The chemical composition of olivine and low‐Ca pyroxene are uniform; Fa in olivine and Fs in low‐Ca pyroxene are, respectively, 19.6 ± 0.2 and 17.0 ± 0.3 (mole%). Huaxi has been classified as an H5 ordinary chondrite, with a shock grade S2, and weathering W0. The weak shock features, rare fractures, and the high porosity (17.6%) indicates that Huaxi is a less compacted meteorite. The preatmospheric radius of Huaxi is ~11 cm, corresponding to ~21 kg. The meteorite experienced a relatively short cosmic‐ray exposure of about 1.6 ± 0.1 Ma. The4He and40Ar retention ages are older than 4.6 Ga implying that Huaxi did not degas after thermal metamorphism on its parent body.
An Impossible Possibility? Jewish Barthianism in Interwar Germany
Authors: Herskowitz Daniel
Published: February 2017

In this essay I examine the Jewish reception of Karl Barth's theology in Germany of the 1930s. This I do through an analysis of a disputed exploration into the possibilities and limitations of the theological principles of dialectical theology for the formulation of a Jewish theology that took place at the time. The publication of Karl Barth's Römerbrief (1919, 1922) generated a great stir among Christian circles in Germany. Profoundly challenging the fundamental assumptions of liberal theology, Barth's ‘dialectical theology' was quickly recognized as an epoch‐making work. But the impact of Barth's theology exceeded its Christian readership. As a corresponding disillusionment of liberal theology in its Jewish version took place among Jews, Barthianism presented itself as a compelling theological model offering a profound rejoinder to the spiritual needs of Jews as well. Yet alongside the recognition of the potentially constructive engagement with Barth's radical thought for a rejuvenated articulation of Jewish theology, Jewish thinkers similarly acknowledged the many challenges and difficulties such a theological encounter implied from a Jewish point of view, thereby projecting their understanding of the Jewish‐Christian difference.
Implementation of NAP4 emergency airway management recommendations in a quaternary‐level pediatric hospital
Authors: Long Elliot , Cincotta Domenic , Grindlay Joanne , Pellicano Anastasia , Clifford Michael , Sabato Stefan ,   the Paediatric Research in Emergency Departments International Collaborative (PREDICT)
Published: February 2017

Emergency airway management, particularly outside of the operating room, is associated with a high incidence of life‐threatening adverse events. Based on the recommendations of the 4th National Audit Project, we aimed to develop hospital‐wide systems changes to improve the safety of emergency airway management. We describe a framework for governance in the form of a hospital airway special interest group. We describe the development and implementation of the following systems changes: 1. A local intubation algorithm modified from the Difficult Airway Society's plan A‐B‐C‐D approach, including clear pathways for airway escalation, and emphasizing the concepts of resuscitation prior to intubation, planning for failure, and avoidance of fixation error. 2. Simplified and standardized airway equipment located in identical airway carts in all critical care areas. 3. A preintubation checklist and equipment template to standardize preparation for airway management. 4. Availability of continuous waveform endtidal capnography in all critical care areas for confirmation of correct endotracheal tube placement. 5. Multidisciplinary team training to address the technical and nontechnical aspects of nonoperating room intubation. In addition, we describe methodology for ongoing monitoring of performance through a quality assurance framework. In conclusion, changes in the process of emergency airway management at a hospital level are feasible through collaboration. Their impact on patient‐based outcomes requires further study.
Signaling about Norms: Socialization under Strategic Uncertainty
Authors: Adriani Fabrizio , Sonderegger Silvia
Published: February 2017

We consider a signaling model in which adults possess information about the dominant social norm. Children want to conform to whatever norm is dominant but, lacking accurate information, take the observed behavior of their parents as representative. We show that this causes a signaling distortion in adult behavior, even in the absence of conflicts of interest. Parents adopt attitudes that encourage their children to behave in a socially safe way (i.e., the way that would be optimal under maximum uncertainty about the prevailing social norm). We discuss applications to sexual attitudes, collective reputation, and trust.
Turnout and Closeness: Evidence from 60 Years of Bavarian Mayoral Elections
Authors: Arnold Felix
Published: February 2017

One prediction of the calculus of voting is that electoral closeness positively affects turnout via a higher probability of one vote being decisive. I test this theory with data on all mayoral elections in the German state of Bavaria between 1946 and 2009. Importantly, I use constitutionally prescribed two‐round elections to measure electoral closeness and thereby improve on existing work that mostly uses ex post measures that are prone to endogeneity. The results suggest that electoral closeness matters: a one standard deviation increase in closeness increases turnout by 1.27 percentage points, which corresponds to 1/7 of a standard deviation in this variable. I also evaluate how other factors such as electorate size or rain on election day affect turnout differentially depending on the closeness of the race. While rain decreases turnout on average, this effect is mitigated in close elections, as indicated by a positive interaction effect of the two variables.
Measuring Labour Services: Quality‐Adjusting the Entry and Exit of Workers
Authors: von Brasch Thomas , Cappelen Ådne , Iancu Diana‐Cristina
Published: February 2017

Many statistical agencies use the sum of hours worked when measuring labour services. This implies that all workers provide work of equal quality. Various indices for adjusting for labour quality have been employed in a large body of literature. However, this literature has not yet addressed the issue of how to quality‐adjust the impact of workers entering and exiting the labour market. We outline a theoretical framework for dealing with quality adjustment of labour services caused by workers entering and exiting employment. To illustrate the theoretical framework, we use the case of Norway in the period 1997–2013. The impact on labour services due to our quality adjustment of net entry is found to be cyclical. While the adjustment for the quality of net entry amounts to about −0.3 percentage points annually during expansions, it is offset by about the same magnitude during contractions.
Beyond Thin Credit Files
Authors: Smith Marvin M. , Henderson Christopher
Published: February 2017

Objective

In the world of credit, the moving force for a consumer is the credit score. A high credit score will help secure good credit with favorable terms and even a somewhat lower credit score might assist in getting credit, albeit at more costly terms. However, no credit score is likely to be a deterrent to gaining credit. A credit score might also be required to gain services other than financial credit, such as access to a rental property or obtaining certain types of jobs. This is especially problematic for individuals who have insufficient credit information to derive credit scores and who are classified as thin‐file individuals. Some maintain that there might be individuals with thin files who are creditworthy despite not having a credit score. This report explores this assertion quantitatively and investigates if there are any identifiable patterns in former thin‐file individuals qualifying for credit scores. The study also discusses the use of alternative data to assist in scoring thin‐file individuals.

Methods

We use the Equifax database to follow two samples of thin‐file individuals with no credit scores for at least four years in order to develop a timeline indicating when they obtained sufficient credit to qualify for a credit score.

Results

Our findings document that many individuals with thin files in fact proved to be creditworthy. Some of them even became homeowners. Their eventual credit scores ranged from below 520 to 740 and above. Moreover, most of them qualified for a credit score within three to four years. Furthermore, during this four‐year timeframe, the majority received credit scores in the first and second years.

Conclusions

Even though many individuals with thin files qualify for credit scores within a relatively short period of time, the wait time might be made even shorter if alternative credit data are used to help score them.
Evolutionary trajectories of duplicated FT homologues and their roles in soybean domestication
Authors: Wu Faqiang , Sedivy Eric J. , Price William Brian , Haider Waseem , Hanzawa Yoshie
Published: February 2017

To clarify the molecular bases of flowering time evolution in crop domestication, here we investigate the evolutionary fates of a set of four recently duplicated genes in soybean: FT2a, FT2b, FT2c and FT2d that are homologues of the floral inducer FLOWERING LOCUS T (FT). While FT2a maintained the flowering inducer function, other genes went through contrasting evolutionary paths. FT2b evolved attenuated expression potentially associated with a transposon insertion in the upstream intergenic region, while FT2c and FT2d obtained a transposon insertion and structural rearrangement, respectively. In contrast to FT2b and FT2d whose mutational events occurred before the separation of G. max and G. soja, the evolution of FT2c is a G. max lineage specific event. The FT2c allele carrying a transposon insertion is nearly fixed in soybean landraces and differentiates domesticated soybean from wild soybean, indicating that this allele spread at the early stage of soybean domestication. The domesticated allele causes later flowering than the wild allele under short day and exhibits a signature of selection. These findings suggest that FT2c may have underpinned the evolution of photoperiodic flowering regulation in soybean domestication and highlight the evolutionary dynamics of this agronomically important gene family.
Validity and Reliability Study of the Scale for Determining the Civic-mindedness Levels of Teaching Staff
Authors: Yeşil Rüştü
Published: February 2017

use after also being checked by linguists. The validity analysis of the scale for the data collected was performed with exploratory factor analysis and item-total correlation tests, while the property of reliability was determined using the Cronbach’s alpha internal consistency coefficient and the stability test was carried out by determining the relationship between two applications conducted at an interval of the five weeks. The scale, which is called the “Scale for Determining the Civic-Mindedness Levels of Individuals” is a five-step Likert-type scale and consists of 27 items that can be collected under three factors. The factor names are “Openness to Criticism/Development”, “Participation/Activeness” and “Lack of Prejudice/Flexibility”. The KMO value of the scale was 0.956; and the Bartlett Test values were x2=11001.719; sd=351; p<0.000. Items in the scale accounted for 56.619% of the total variance. As a result of the confirmatory factor analysis, the χ2 value was 808.07 and the degree of freedom was 321. Χ2/df is 2.51. The fit indices of the scale were determined as RMSEA=0.067; S-RMR=0.049; NFI=0.97. The item-total corrected correlation coefficients of the items in the scale varied between 0.40 and 0.703 (p<.01). The reliability coefficient of the scale was Cronbach’s alpha at 0.954 and the stability coefficients of the items were between 0.496 and 0.674 (p<,01).
Examination of Photovoltaic Silicon Module Degradation Under High-Voltage Bias and Damp Heat by Electroluminescence
Authors: Brecl Kristijan , Bokalič Matevž , Topič Marko
Published: February 2017

The photovoltaic (PV) modules are in PV arrays normally connected in series and thus some of them are exposed to high system voltages since frames of the PV modules are grounded. To predict the long-term PV system energy output and PV module lifetime, it is very important to understand and take into account the degradation process of PV modules under high-voltage stress. Accelerated tests under damp heat (over 1300 h of DH85/60; RH = 85%, T = 60 °C) of in-house developed monocrystalline silicon PV modules with p-type solar cells were preformed while connected to a positive or negative voltage bias of 1000 V. The negative biased modules exhibited just a little degradation, while the positive biased modules degraded rapidly. We identified three degradation mechanisms: cell degradation, silver corrosion, and EVA evaporation. The degradation mechanisms contribute to almost 15% of the performance loss of the 1000 V positive biased modules after more than 1300 h of DH85/60 testing, while the power degradation of the negative biased modules remains below 3%.
A Damage Evaluation Model of Turbine Blade for Gas Turbine
Authors: Zhou Dengji , Wei Tingting , Zhang Huisheng , Ma Shixi , Weng Shilie
Published: February 2017

Current maintenance, having a great impact on the safety, reliability and economics of a gas turbine, becomes the major obstacle for the application of gas turbines in energy field. An effective solution is to process condition based maintenance (CBM) thoroughly for gas turbines. Maintenance of high temperature blade, accounting for the most of the maintenance costs and time, is the crucial section of gas turbine maintenance. The suggested life of high temperature blade by original equipment manufacturer (OEM) is based on several certain operating conditions, which is used for time based maintenance (TBM). Thus, for the requirement of gas turbine CBM, a damage evaluation model is demanded to estimate the life consumption online. A physics-based model is built, consisting of thermodynamic performance simulation model, stress estimation model, thermal estimation model, and interactive damage analysis model. Unmeasured parameters are simulated by the thermodynamic performance simulation model, as the input of the stress estimation model and the thermal estimation model. Due to the ability to analyze online data, this model can be used to calculate online damage and support CBM decision. Then the stress and temperature distribution of blades will become as the input of the creep damage analysis model and the fatigue damage analysis model. The interactive damage of blades will be evaluated based on the creep and fatigue analysis results. To validate this physics-based model, it is used to calculate the lifes of high temperature blade under several certain operating conditions. And the results are compared to the suggestion value of OEM. An application case is designed to evaluate the application effect of this model. The result shows that the relative error of this model is less than 10.4% in selected cases. And it can cut overhaul costs and increase the availability of gas turbines significantly. Finally, a simple application of this model is proposed to show its functions. The physical-based damage evaluation model proposed in this paper is found to be a useful tool to tracing the online life consumption of a high temperature blade, to support the implementation of CBM for gas turbines, and to guarantee the reliability of gas turbines with lowest maintenance costs.
Brachytherapy treatment planning commissioning: effect of the election of proper bibliography and finite size of TG‐43 input data on standard treatments
Authors: Valdés Christian N. , Píriz Gustavo H. , Lozano Enrrique
Published: February 2017

The aim of this work is to evaluate the performance of a commercial brachytherapy treatment planning system (TPS) with TG‐43 Vendors Input Data (VID), analyze possible discrepancies with respect to a proper reference source and its implications for standard treatments, and judge the effectiveness of certain widespread recommended quality controls to find potential errors related with the interpolations of TG‐43 VID tables. The TPS evaluated was a BrachyVision 8.6 loaded with TG‐43 VID for a VariSource high‐dose‐rate source (Vs2000). The reference data chosen were the TG‐43 data published in the literature. In the first step, we compared TG‐43 VID with respect to the chosen reference data. Next, we used percent dose‐rate differences in a point array matrix to compare the outcomes of the TPS on standard treatment setup with respect to an in‐house developed program (MATLAB R2009a‐based) loaded with the chosen full TG‐43 reference data. The cases with major discrepancies were evaluated using the gamma‐index analysis. The comparison with the reference data indicated a lack of sample in the angles between near to the tip (between ) and cable () of the , which causes a dose underestimation of approximately 17% in the investigated points due to inaccurate interpolations. The differences over 2% encompassed approximately 17% of the surrounding source volume. These results have special relevance in treatment using one applicator with a few dwell steps or in Fletcher treatments where 10% dose underestimates were identified within the tumor or in organs at risk, respectively. Our results suggest that the differences found in the TPS under study are created by a lack of information on the angles in high‐gradient zones in the , which generates important differences in dosimetric results. In contrast, the gamma analysis shows very good results (between 90% and 100% of passed points) in the analyzed treatments (one dwell and Fletcher). Further studies are required to exclude the possibility of finding noticeable effects in the DVH of treatment plans caused by the discrepancies here described. To achieve more strict control over the TPS dose‐rate calculation, we recommend using QA test thinking in a source with nonaxial symmetry, adding a control point on the angles of the high‐dose gradient zones (e.g., between 0° and 15° and between 165° and 180°). More studies are required to achieve full understanding of the clinical implication of such discrepancies.

PACS number: 87.55.Qr
Long‐term evaluation and cross‐checking of two geometric calibrations of kV and MV imaging systems for Linacs
Authors: Chiu Tsuicheng D. , Yan Yulong , Foster Ryan , Mao Weihua
Published: February 2017

Geometric or mechanical accuracy of kV and MV imaging systems of two Varian TrueBeam linacs have been monitored by two geomertirc calibration systems, Varian IsoCal geometric calibration system and home‐developed gQA system. Results of both systems are cross‐checked and the long‐term geometric stabilities of linacs are evaluated. Two geometric calibration methodologies have been used to assess kV and MV imaging systems and their coincidence periodically on two TrueBeam linacs for about one year. Both systems analyze kV or MV projection images of special designed phantoms to retrieve geometric parameters of the imaging systems. The isocenters — laser isocenter and centers of rotations of kV imager and EPID — are then calculated, based on results of multiple projections from different angles. Long‐term calibration results from both systems are compared for cross‐checking. There are 24 sessions of side‐by‐side calibrations performed by both systems on two TrueBeam linacs. All the disagreements of isocenters between two calibrations systems are less than 1 mm with SD. Most of the large disagreements occurred in vertical direction (AP direction), with an averaged disagreement of 0.45 mm. The average disagreements of isocenters are 0.09 mm in other directions. Additional to long‐term calibration monitoring, for the accuracy test, special tests were performed by misaligning QA phantoms on purpose (5 mm away from setup isocenter in AP, SI, and lateral directions) to test the liability performance of both systems with the known deviations. The errors are within 0.5 mm. Both geometric calibration systems, IsoCal and gQA, are capable of detecting geometric deviations of kV and MV imaging systems of linacs. The long‐term evaluation also shows that the deviations of geometric parameters and the geometric accuracies of both linacs are small and very consistent during the one‐year study period.

PACS number: 87.56.Fc
Evaluation of GMI and PMI diffeomorphic‐based demons algorithms for aligning PET and CT Images
Authors: Yang Juan , Wang Hongjun , Zhang You , Yin Yong
Published: February 2017

Fusion of anatomic information in computed tomography (CT) and functional information in positron emission tomography (PET) is crucial for accurate differentiation of tumor from benign masses, designing radiotherapy treatment plan and staging of cancer. Although current PET and CT images can be acquired from combined PET/CT scanner, the two acquisitions are scanned separately and take a long time, which may induce potential positional errors in global and local caused by respiratory motion or organ peristalsis. So registration (alignment) of whole‐body PET and CT images is a prerequisite for their meaningful fusion. The purpose of this study was to assess the performance of two multimodal registration algorithms for aligning PET and CT images. The proposed gradient of mutual information (GMI)‐based demons algorithm, which incorporated the GMI between two images as an external force to facilitate the alignment, was compared with the point‐wise mutual information (PMI) diffeomorphic‐based demons algorithm whose external force was modified by replacing the image intensity difference in diffeomorphic demons algorithm with the PMI to make it appropriate for multimodal image registration. Eight patients with esophageal cancer(s) were enrolled in this IRB‐approved study. Whole‐body PET and CT images were acquired from a combined PET/CT scanner for each patient. The modified Hausdorff distance () was used to evaluate the registration accuracy of the two algorithms. Of all patients, the mean values and standard deviations (SDs) of were 6.65 voxels and 6.01 after the GMI‐based demons and the PMI diffeomorphic‐based demons registration algorithms respectively. Preliminary results on oncological patients showed that the respiratory motion and organ peristalsis in PET/CT esophageal images could not be neglected, although a combined PET/CT scanner was used for image acquisition. The PMI diffeomorphic‐based demons algorithm was more accurate than the GMI‐based demons algorithm in registering PET/CT esophageal images.

PACS numbers: 87.57.nj, 87.57. Q‐, 87.57.uk
Development of an automatic evaluation method for patient positioning error
Authors: Kubota Yoshiki , Tashiro Mutsumi , Shinohara Ayaka , Abe Satoshi , Souda Saki , Okada Ryosuke , Ishii Takayoshi , Kanai Tatsuaki , Ohno Tatsuya , Nakano Takashi
Published: February 2017

Highly accurate radiotherapy needs highly accurate patient positioning. At our facility, patient positioning is manually performed by radiology technicians. After the positioning, positioning error is measured by manually comparing some positions on a digital radiography image (DR) to the corresponding positions on a digitally reconstructed radiography image (DRR). This method is prone to error and can be time‐consuming because of its manual nature. Therefore, we propose an automated measuring method for positioning error to improve patient throughput and achieve higher reliability. The error between a position on the DR and a position on the DRR was calculated to determine the best matched position using the block‐matching method. The zero‐mean normalized cross‐correlation was used as our evaluation function, and the Gaussian weight function was used to increase importance as the pixel position approached the isocenter. The accuracy of the calculation method was evaluated using pelvic phantom images, and the method's effectiveness was evaluated on images of prostate cancer patients before the positioning, comparing them with the results of radiology technicians' measurements. The root mean square error (RMSE) of the calculation method for the pelvic phantom was . The coefficients between the calculation method and the measurement results of the technicians were 0.989 for the phantom images and 0.980 for the patient images. The RMSE of the total evaluation results of positioning for prostate cancer patients using the calculation method was . Using the proposed method, we successfully measured residual positioning errors. The accuracy and effectiveness of the method was evaluated for pelvic phantom images and images of prostate cancer patients. In the future, positioning for cancer patients at other sites will be evaluated using the calculation method. Consequently, we expect an improvement in treatment throughput for these other sites.

PACS number: 87
Generation and verification of QFix kVue Calypso‐compatible couch top model for a dedicated stereotactic linear accelerator with FFF beams
Authors: Gardner Stephen J. , Gulam Misbah , Song Kwang , Li Haisen , Huang Yimei , Zhao Bo , Qin Yujiao , Snyder Karen , Kim Jinkoo , Gordon James , Chetty Indrin J. , Wen Ning
Published: February 2017

This study details the generation, verification, and implementation of a treatment planning system (TPS) couch top model for patient support system used in conjunction with a dedicated stereotactic linear accelerator. Couch top model was created within the TPS using CT simulation images of the kVue Calpyso‐compatible couchtop (with rails). Verification measurements were compared to TPS dose prediction for different energies (6 MV FFF and 10 MV FFF) and rail configurations (rails in and rails out) using: 1) central axis point‐dose measurements with pinpoint chamber in water‐equivalent phantom at 42 gantry angles for various field sizes (); and 2) Gafchromic EBT3 film parallel to beam in acrylic slab to assess changes in surface and percent depth doses in PA geometry. To assess sensitivity of delivered dose to variations in patient lateral position, measurements at central axis using the pinpoint chamber geometry were taken at lateral couch displacements of 2, 5, and 10 mm for 6 MV FFF. The maximum percent difference for point‐dose measurements was 3.24% (6 MV FFF) and 2.30% (10 MV FFF). The average percent difference for point‐dose measurements was less than 1.10% for all beam energies and rail geometries. The maximum percent difference between calculated and measured dose can be as large as 13.0% if no couch model is used for dose calculation. The presence of the couch structures also impacts surface dose and PDD, which was evaluated with Gafchromic film measurements. The upstream shift in the depth of dose maximum (dmax) was found to be 10.5 mm for 6 MV FFF and 5.5 mm for 10 MV FFF for ‘Rails In’ configuration. Transmission of the treatment beam through the couch results in an increase in surface dose (absolute percentage) of approximately 50% for both photon energies (6 MV FFF and 10 MV FFF). The largest sensitivity to lateral shifts occurred at the lateral boundary of the rail structures. The mean magnitude (standard deviation) of the deviation between shifted and centered measurements over all field sizes tested was 0.61% (0.61%) for 2 mm shifts, 0.46% (0.67%) for 5 mm shifts, and 0.86% (1.46%) for 10 mm shifts.

PACS numbers: 87.56.‐v, 87.56.Da, 87.56.Fc
Quality control of CT systems by automated monitoring of key performance indicators: a two‐year study
Authors: Nowik Patrik , Bujila Robert , Poludniowski Gavin , Fransson Annette
Published: February 2017

The purpose of this study was to develop a method of performing routine periodical quality controls (QC) of CT systems by automatically analyzing key performance indicators (KPIs), obtainable from images of manufacturers' quality assurance (QA) phantoms. A KPI pertains to a measurable or determinable QC parameter that is influenced by other underlying fundamental QC parameters. The established KPIs are based on relationships between existing QC parameters used in the annual testing program of CT scanners at the Karolinska University Hospital in Stockholm, Sweden. The KPIs include positioning, image noise, uniformity, homogeneity, the CT number of water, and the CT number of air. An application (MonitorCT) was developed to automatically evaluate phantom images in terms of the established KPIs. The developed methodology has been used for two years in clinical routine, where CT technologists perform daily scans of the manufacturer's QA phantom and automatically send the images to MonitorCT for KPI evaluation. In the cases where results were out of tolerance, actions could be initiated in less than 10 min. 900 QC scans from two CT scanners have been collected and analyzed over the two‐year period that MonitorCT has been active. Two types of errors have been registered in this period: a ring artifact was discovered with the image noise test, and a calibration error was detected multiple times with the CT number test. In both cases, results were outside the tolerances defined for MonitorCT, as well as by the vendor. Automated monitoring of KPIs is a powerful tool that can be used to supplement established QC methodologies. Medical physicists and other professionals concerned with the performance of a CT system will, using such methods, have access to comprehensive data on the current and historical (trend) status of the system such that swift actions can be taken in order to ensure the quality of the CT examinations, patient safety, and minimal disruption of service

PACS numbers: 87.57.C‐, 87.57.N‐, 87.57.Q‐
Dosimetric comparison of Acuros XB with collapsed cone convolution/superposition and anisotropic analytic algorithm for stereotactic ablative radiotherapy of thoracic spinal metastases
Authors: Zhen Heming , Hrycushko Brian , Lee Huichen , Timmerman Robert , Pompoš Arnold , Stojadinovic Strahinja , Foster Ryan , Jiang Steve B. , Solberg Timothy , Gu Xuejun
Published: February 2017

The aim of this study is to compare the recent Eclipse Acuros XB (AXB) dose calculation engine with the Pinnacle collapsed cone convolution/superposition (CCC) dose calculation algorithm and the Eclipse anisotropic analytic algorithm (AAA) for stereotactic ablative radiotherapy (SAbR) treatment planning of thoracic spinal (T‐spine) metastases using IMRT and VMAT delivery techniques. The three commissioned dose engines (CCC, AAA, and AXB) were validated with ion chamber and EBT2 film measurements utilizing a heterogeneous slab‐geometry water phantom and an anthropomorphic phantom. Step‐and‐shoot IMRT and VMAT treatment plans were developed and optimized for eight patients in Pinnacle, following our institutional SAbR protocol for spinal metastases. The CCC algorithm, with heterogeneity corrections, was used for dose calculations. These plans were then exported to Eclipse and recalculated using the AAA and AXB dose calculation algorithms. Various dosimetric parameters calculated with CCC and AAA were compared to that of the AXB calculations. In regions receiving above 50% of prescription dose, the calculated CCC mean dose is 3.1%–4.1% higher than that of AXB calculations for IMRT plans and 2.8%–3.5% higher for VMAT plans, while the calculated AAA mean dose is 1.5%–2.4% lower for IMRT and 1.2%–1.6% lower for VMAT. Statistically significant differences () were observed for most GTV and PTV indices between the CCC and AXB calculations for IMRT and VMAT, while differences between the AAA and AXB calculations were not statistically significant. For T‐spine SAbR treatment planning, the CCC calculations give a statistically significant overestimation of target dose compared to AXB. AAA underestimates target dose with no statistical significance compared to AXB. Further study is needed to determine the clinical impact of these findings.

PACS number: 87.55.D‐, 87.53.Ly
Comparison of measured Varian Clinac 21EX and TrueBeam accelerator electron field characteristics
Authors: Lloyd Samantha A.M. , Zavgorodni Sergei , Gagne Isabelle M.
Published: February 2017

Dosimetric comparisons of radiation fields produced by Varian's newest linear accelerator, the TrueBeam, with those produced by older Varian accelerators are of interest from both practical and research standpoints. While photon fields have been compared in the literature, similar comparisons of electron fields have not yet been reported. In this work, electron fields produced by the TrueBeam are compared with those produced by Varian's Clinac 21EX accelerator. Diode measurements were taken of fields shaped with electron applicators and delivered at 100 cm SSD, as well as those shaped with photon MLCs without applicators and delivered at 70 cm SSD for field sizes ranging from to at energies between 6 and 20 MeV. Additionally, EBT2 and EBT3 radio‐chromic film measurements were taken of an MLC‐shaped aperture with closed leaf pairs delivered at 70 cm SSD using 6 and 20 MeV electrons. The 6 MeV fields produced by the TrueBeam and Clinac 21EX were found to be almost indistinguishable. At higher energies, TrueBeam fields shaped by electron applicators were generally flatter and had less photon contamination compared to the Clinac 21EX. Differences in PDDs and profiles fell within 3% and 3 mm for the majority of measurements. The most notable differences for open fields occurred in the profile shoulders for the largest applicator field sizes. In these cases, the TrueBeam and Clinac 21EX data differed by as much as 8%. Our data indicate that an accurate electron beam model of the Clinac 21EX could be used as a starting point to simulate electron fields that are dosimetrically equivalent to those produced by the TrueBeam. Given that the Clinac 21EX shares head geometry with Varian's iX, Trilogy, and Novalis TX accelerators, our findings should also be applicable to these machines.

PACS number: 87.56.bd
Effects of changing modulation and pitch parameters on tomotherapy delivery quality assurance plans
Authors: Binny Diana , Lancaster Craig M. , Harris Selina , Sylvander Steven R.
Published: February 2017

This study was aimed at investigating delivery quality assurance (DQA) discrepancies observed for helical tomotherapy plans. A selection of tomotherapy plans that initially failed the DQA process was chosen for this investigation. These plans failed the fluence analysis as assessed using gamma criteria (3%, 3 mm) with radiographic film. Each of these plans was modified (keeping the planning constraints the same), beamlets rebatched and reoptimized. By increasing and decreasing the modulation factor, the fluence in a circumferential plane as measured with a diode array was assessed. A subset of these plans was investigated using varied pitch values. Metrics for each plan that were examined were point doses, fluences, leaf opening times, planned leaf sinograms, and uniformity indices. In order to ensure that the treatment constraints remained the same, the dose‐volume histograms (DVHs) of all the modulated plans were compared to the original plan. It was observed that a large increase in the modulation factor did not significantly improve DVH uniformity, but reduced the gamma analysis pass rate. This also increased the treatment delivery time by slowing down the gantry rotation speed which then increases the maximum to mean non‐zero leaf open time ratio. Increasing and decreasing the pitch value did not substantially change treatment time, but the delivery accuracy was adversely affected. This may be due to many other factors, such as the complexity of the treatment plan and site. Patient sites included in this study were head and neck, right breast, prostate, abdomen, adrenal, and brain. The impact of leaf timing inaccuracies on plans was greater with higher modulation factors. Point‐dose measurements were seen to be less susceptible to changes in pitch and modulation factors. The initial modulation factor used by the optimizer, such that the TPS generated ‘actual’ modulation factor within the range of 1.4 to 2.5, resulted in an improved deliverable plan.

PACS number: 87.55.‐x, 87.55.Qr, 87.55.D‐