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ABSTRACT: Eosinophilic oesophagitis (EoE) has evolved from a supposedly rare entity to one whose incidence rates are approaching that of inflammatory bowel disease. The factors responsible for this apparent increase in the incidence remain obscure.
To assess various endoscopist and pathologist factors that might affect the frequency of EoE being detected in a well-defined North American population.
Increased endoscopist and pathologist awareness has contributed to the increased clinical recognition of EoE.
Cases of EoE were identified systematically using population-based pathology and endoscopy databases from January 2004 to December 2008 in Calgary, Canada (population 1.25 million). EoE frequency was estimated with time trend analysis. Characteristics of individual endoscopists (n = 45) were compared with diagnostic rates.
Crude population incidence of EoE increased from 2.1 per 10(5) in 2004 to 11.0 per 10(5) in 2008: an annual increase of 39% (P < 0.0001). The frequency in men was 4.5 times higher than in women (95% CI: 3.51-5.76). In patients presenting with dysphagia oesophageal biopsy rates increased from 17.0% in 2004 to 41.3% of EGDs in 2008: an annual rise of 26% (P < 0.0001). On multivariate regression analysis, those endoscopists with higher biopsy rates were more likely to make the diagnosis of EoE (P = 0.008). To include or exclude the diagnosis, typical histological features of EoE were reported more often by pathologists in 2008 as compared to 2004 (P = 0.01 & P < 0.0001 respectively).
The incidence of eosinophilic oesophagitis continues to rise in the general population, in part due to increasing oesophageal biopsy rates and a more detailed histological evaluation of specimens. The biopsy rate of an endoscopist is an indicator for a higher diagnostic yield.
Alimentary Pharmacology & Therapeutics 09/2012; 36(10):950-8. · 3.77 Impact Factor
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Peter Beck,
Andrea Zechner,
Sofia Rollet,
Thomas Berger,
Robert Bergmann,
Michael Hajek,
Christian Hranitzky,
Marcin Latocha,
Günther Reitz,
Hannes Stadtmann,
Norbert Vana,
Michael Wind, P Beck,
S Rollet,
M Latocha,
M Wind,
M R Bergmann,
N Hajek,
Vana
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ABSTRACT: The AIT Austrian Institute of Technology coor-dinates the project MATSIM (MATROSHKA Simulation) in collaboration with the Vienna University of Technology and the German Aerospace Center, to perform FLUKA Monte Carlo simulations of the MATROSHKA numerical phantom irradi-ated under reference radiation field conditions as well as for the radiation environment at the International Space Station (ISS). MATSIM is carried out as co-investigation of the ESA ELIPS projects SORD and RADIS (commonly known as MATROSHKA), an international collaboration of more than 18 research institutes and space agencies from all over the world, under the science and project lead of the German Aerospace Center. During MATSIM a computer tomography scan of the MATROSHKA phantom has been converted into a high resolution 3-dimensional voxel model. The energy imparted and absorbed dose distribution inside the model is determined for various radiation fields. The major goal of the MATSIM project is the validation of the numerical model under reference radiation conditions and further investigations under the radiation environment at ISS. In this report we compare depth dose distributions inside the phantom measured with ther-moluminescence detectors (TLDs) and an ionization chamber with FLUKA Monte Carlo particle transport simulations due to 60 Co photon exposure. Further reference irradiations with neutrons, protons and heavy ions are planned. The fully validated numerical model MATSIM will provide a perfect tool to assess the radiation exposure to humans during current and future space missions to ISS, Moon, Mars and beyond. Index Terms—FLUKA Monte Carlo simulation, MATROSHKA dosimetric phantom, space dosimetry, voxel model.
IEEE Transactions on Nuclear Science 08/2011; 58(4):1921-6. · 1.45 Impact Factor
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ABSTRACT: Using protons for the treatment of ocular melanoma (especially of posterior pole tumours), the radiation quality of the beam must be precisely assessed to preserve the vision and to minimise the damage to healthy tissue. The radiation quality of a therapeutic proton beam at the Centre Antoine Lacassagne in Nice (France) was measured using microdosimetric techniques, i.e. a miniaturised version of a tissue-equivalent proportional counter. Measurements were performed in a 1-µm site at different depths in a Lucite phantom. Experimental data showed a significant increase in the beam quality at the distal edge of the spread-out Bragg peak (SOBP). In this paper, the numerical simulation of the experimental setup is done with the FLUKA Monte Carlo radiation transport code. The calculated microdosimetric spectra are compared with the measured ones at different depths in tissue for a monoenergetic proton beam (E=62 MeV) and for a modulated SOBP. Numerically and experimentally predicted relative biological effectiveness values are in good agreement. The calculated frequency-averaged and dose-averaged lineal energy mean values are consistent with measured data.
Radiation Protection Dosimetry 02/2011; 143(2-4):445-9. · 0.82 Impact Factor
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ABSTRACT: We investigate the energy response of RADFET to high energy photons, electrons, protons and neutrons with FLUKA Monte Carlo simulation code. We combine Monte Carlo and device simulations to describe radiation effects in the RADFET gate oxide due to photon and proton exposure. Comparisons with photon irradiation measurements show reasonable agreement.
IEEE Transactions on Nuclear Science 01/2010; · 1.45 Impact Factor
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ABSTRACT: The tissue equivalent proportional counter is a versatile
instrument used to determine the absorbed dose
and the quality of an unknown radiation field, but it does
not directly measure the operational quantity ambient
dose equivalent H*(10). In this paper, simulated and measured
values of H*(10) are compared, and some corrections
are applied in order to give a reliable estimate of
H*(10) in a complex radiation field generated by high energy
carbon ions.
Nuclear technology 10/2009; 168(1):118-122. · 0.60 Impact Factor
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P Beck
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ABSTRACT: Cosmic radiation was discovered successfully in the beginning of the twentieth century by the Austrian Nobel Price winner Victor Hess. Radiation effects to humans are of major concern during human space missions and also due to the increasing aviation altitudes and flight time. ICRP recommendations lead to adaptations of the Basic Safety Standards by the European Council. Beginning in the 1990 s up to now, significant improvements and findings in aviation dosimetry and epidemiology were done word-wide. Five research projects on measurements and modelling cosmic radiation exposure were supported by European Research Framework Programmes. In-flight measurements with remarkable agreement (+/-25%) were carried out to validate calculation codes for routine dose assessment within +/-30% for galactic cosmic radiation. Measurements and improvements of modelling radiation exposure due to solar particle events (SPE) is still an objective for future research projects.
Radiation Protection Dosimetry 09/2009; 136(4):244-50. · 0.82 Impact Factor
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J F Bottollier-Depois, P Beck,
B Bennett,
L Bennett,
R Bütikofer,
I Clairand,
L Desorgher,
C Dyer,
E Felsberger,
E Flückiger, [......],
M Latocha,
B Lewis,
G Leuthold,
T Maczka,
V Mares,
M J McCall,
K O'Brien,
S Rollet,
W Rühm,
F Wissmann
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ABSTRACT: The assessment of the exposure to cosmic radiation onboard aircraft is one of the preoccupations of bodies responsible for radiation protection. Cosmic particle flux is significantly higher onboard aircraft than at ground level and its intensity depends on the solar activity. The dose is usually estimated using codes validated by the experimental data. In this paper, a comparison of various codes is presented, some of them are used routinely, to assess the dose received by the aircraft crew caused by the galactic cosmic radiation. Results are provided for periods close to solar maximum and minimum and for selected flights covering major commercial routes in the world. The overall agreement between the codes, particularly for those routinely used for aircraft crew dosimetry, was better than +/-20 % from the median in all but two cases. The agreement within the codes is considered to be fully satisfactory for radiation protection purposes.
Radiation Protection Dosimetry 09/2009; 136(4):317-23. · 0.82 Impact Factor
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ABSTRACT: AVIDOS is a computer code used for the dose assessment of aircraft crew exposed to cosmic radiation. The code employs a multiparameter model built upon simulations of cosmic radiation exposure done using the FLUKA Monte Carlo code. AVIDOS calculates both ambient dose equivalent H*(10) and effective dose E for flight routes over the whole world at typically used altitudes and for the full range of solar activity. The dose assessment procedure using AVIDOS is accredited by the Austrian office for accreditation according to European regulations and is valid in the whole Europe. AVIDOS took part in an international comparison of different codes assessing radiation exposure of aircraft crew where a fully satisfactory agreement between codes has been found. An online version of AVIDOS with user friendly interface is accessible to public under the internet address: http://avidos.healthphysics.at.
Radiation Protection Dosimetry 08/2009; 136(4):286-90. · 0.82 Impact Factor
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Radiation Protection Dosimetry 01/2009; 136(4):231. · 0.82 Impact Factor
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ABSTRACT: Radiation exposure of aircraft crew caused by cosmic radiation is regulated in Europe by the European Community Council Directive 96/29/EURATOM and implemented into law in almost every country of the European Union. While the galactic cosmic radiation (GCR) leads on average to an exposure of about 3 mSv per year, solar cosmic radiation can lead to 1 mSv per one subsonic flight during solar storm periods. Compared to GCR, solar cosmic radiation shows a much softer proton spectrum but with a larger contribution of several orders of magnitude. This is the reason for the large radiation exposure in high northern and southern geographic latitudes during solar particle events. Here an overview of active radiation in-flight measurements undertaken during solar storms is given. In particular, tissue-equivalent proportional counter on-board measurements are shown and the radiation quality during solar storm periods with that for GCR is compared.
Radiation Protection Dosimetry 01/2009; 136(4):297-303. · 0.82 Impact Factor
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P Beck,
D T Bartlett,
P Bilski,
C Dyer,
E Flückiger,
N Fuller,
P Lantos,
G Reitz,
W Rühm,
F Spurny,
G Taylor,
F Trompier,
F Wissmann
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ABSTRACT: Dose assessment procedures for cosmic radiation exposure of aircraft crew have been introduced in most European countries in accordance with the corresponding European directive and national regulations. However, the radiation exposure due to solar particle events is still a matter of scientific research. Here we describe the European research project CONRAD, WP6, Subgroup-B, about the current status of available solar storm measurements and existing models for dose estimation at flight altitudes during solar particle events leading to ground level enhancement (GLE). Three models for the numerical dose estimation during GLEs are discussed. Some of the models agree with limited experimental data reasonably well. Analysis of GLEs during geomagnetically disturbed conditions is still complex and time consuming. Currently available solar particle event models can disagree with each other by an order of magnitude. Further research and verification by on-board measurements is still needed.
Radiation Protection Dosimetry 11/2008; 131(1):51-8. · 0.82 Impact Factor
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ABSTRACT: We describe investigations of RadFET energy response simulated with Geant4 and FLUKA2005 Monte Carlo codes. An analysis of energy deposition is carried out for photon irradiation with energies between 35 keV and 2 MeV. The absorbed dose in the silicon dioxide layer (few hundred nanometers) is compared for both transport codes.
IEEE Transactions on Nuclear Science 09/2007; · 1.45 Impact Factor
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ABSTRACT: As required by the European Directive 96/29/Euratom, radiation exposure due to natural ionizing radiation has to be taken into account at workplaces if the effective dose could become more than 1 mSv per year. An example of workers concerned by this directive is aircraft crew due to cosmic radiation exposure in the atmosphere. Extensive measurement campaigns on board aircrafts have been carried out to assess ambient dose equivalent. A consortium of European dosimetry institutes within EURADOS WG5 summarized experimental data and results of calculations, together with detailed descriptions of the methods for measurements and calculations. The radiation protection quantity of interest is the effective dose, E (ISO). The comparison of results by measurements and calculations is done in terms of the operational quantity ambient dose equivalent, H(10). This paper gives an overview of the EURADOS Aircraft Crew In-Flight Database and it presents a new empirical model describing fitting functions for this data. Furthermore, it describes numerical simulations performed with the Monte Carlo code FLUKA-2005 using an updated version of the cosmic radiation primary spectra. The ratio between ambient dose equivalent and effective dose at commercial flight altitudes, calculated with FLUKA-2005, is discussed. Finally, it presents the aviation dosimetry model AVIDOS based on FLUKA-2005 simulations for routine dose assessment. The code has been developed by Austrian Research Centers (ARC) for the public usage (http://avidos.healthphysics.at).
Radiation Protection Dosimetry 02/2007; 126(1-4):564-7. · 0.82 Impact Factor
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ABSTRACT: The European-Commission-supported project DOSMAX (Dosimetry of Aircrew Exposure to Radiation During Solar Maximum) was aimed at measuring aircrew exposure to cosmic radiation on-board the aircraft during solar maximum. During a dedicated international comparison mission (Co-ordinated Access to Aircraft for Transnational Environmental Research; CAATER) different measurement techniques have been compared by six European institutes (Results of the CAATER Mission, DOSMAX Meeting, Dublin, June 2004). In this paper, we present the tissue-equivalent proportional counter (TEPC) measurements carried out by ARC Seibersdorf research (ARCS), Austria, and Institut de Radioprotection et de Sûreté Nucléaire (IRSN), France, together with a comparison with simulation results under the same conditions. The whole flight campaign consists of four different in-flight investigations performed at two different geographical positions at 12.2 km (FL 400) and 9.8 km (FL 320). One location was chosen above Rome (42 degrees North, 12 degrees East), Italy, for high cut-off rigidity (6.4 GV) and the second above Aalborg (57 degrees North, 10 degrees East), Denmark, for low cut-off rigidity (1.8 GV). The TEPC measurements are presented in terms of absorbed dose and ambient dose equivalent as well as microdosimetric spectra as a function of lineal energy. For the same conditions of the CAATER flights the response of the TEPC has also been simulated by using the Monte Carlo Transport Code FLUKA (version 2003). The results from simulations are compared with measurements and they show a reasonable agreement.
Radiation Protection Dosimetry 02/2007; 125(1-4):412-5. · 0.82 Impact Factor
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ABSTRACT: The response of a tissue equivalent proportional counter (TEPC) in a mixed radiation field with a neutron energy distribution similar to the radiation field at commercial flight altitudes has been studied. The measurements have been done at the CERN-EU High-Energy Reference Field (CERF) facility where a well-characterised radiation field is available for intercomparison. The TEPC instrument used by the ARC Seibersdorf Research is filled with pure propane gas at low pressure and can be used to determine the lineal energy distribution of the energy deposition in a mass of gas equivalent to a 2 microm diameter volume of unit density tissue, of similar size to the nuclei of biological cells. The linearity of the detector response was checked both in term of dose and dose rate. The effect of dead-time has been corrected. The influence of the detector exposure location and orientation in the radiation field on the dose distribution was also studied as a function of the total dose. The microdosimetric distribution of the absorbed dose as a function of the lineal energy has been obtained and compared with the same distribution simulated with the FLUKA Monte Carlo transport code. The dose equivalent was calculated by folding this distribution with the quality factor as a function of linear energy transfer. The comparison between the measured and simulated distributions show that they are in good agreement. As a result of this study the detector is well characterised, thanks also to the numerical simulations the instrument response is well understood, and it's currently being used onboard the aircrafts to evaluate the dose to aircraft crew caused by cosmic radiation.
Radiation Protection Dosimetry 02/2007; 125(1-4):425-8. · 0.82 Impact Factor
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ABSTRACT: A tissue-equivalent-proportional counter (TEPC) instrument has been used as the reference instrument for cosmic radiation measurement at flight altitudes by several institutes. For purposes of characterisation the response of the instrument has been investigated under different standard radiation conditions, in terms of radiation particle, energy and angle of incidence. Photon sources and photon beams of energies up to 6.6 MeV and neutron beams up to 200 MeV were used. To have a better understanding of the shielding influence of the instrument assembly, the angle dependence of response was analysed for several radiation conditions. Specific measurement conditions were simulated with the Monte Carlo transport code, FLUKA. The measured instrument response was compared with simulation results. It was demonstrated, that simulations were very helpful to understand the instrument's response. The TEPC instrument used by the Austrian Research Centre Seibersdorf (ARCS) research simulates the energy deposition in a unit density tissue volume of 2 microm diameter, of similar size to a cell nucleus. Pure propane at low pressure is used as measurement gas. To characterise the instrument at low dose rates background measurements were done 800 m below ground and at the ultra low level laboratory in Gran Sasso, 1380 m below ground. These results were compared with measurements on the Earth's surface at different altitudes on mountains up to 3480 m above sea level. The significant increase of the expected dose rate is well reproduced by the experiments at mountain altitudes. As a result of this study a full characterisation and a thorough understanding of the performance and reliability of the detector was achieved.
Radiation Protection Dosimetry 02/2007; 125(1-4):429-32. · 0.82 Impact Factor
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L Lindborg, P Beck,
J F Bottolier-Depois,
M Latocha,
J Lillhök,
S Rollet,
H Roos,
J Roth,
H Schraube,
F Spurny,
G Stehno,
F Trompier,
F Wissmann
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ABSTRACT: Aircrew is in general receiving a higher average annual dose than other occupationally exposed personnel, and about half of the effective dose is deposited by high-LET neutron secondaries. A recent investigation of the cancer incidence following the atomic bombs at Hiroshima and Nagasaki has put forward the possibility that the relative biological efficiency for neutrons could be underestimated. If so, the effective dose to aircrew from this component would increase and the estimation of this component will become even more important. Different ambient dose equivalent measurement techniques and calculation methods have recently been compared on a dedicated flight. The experimental results are compared with calculations made with the codes EPCARD 3.2 and an updated version of FLUKA and different galactic proton spectra. The aircraft circulated within the target areas at two constant altitudes with a flight route variation of only about 1 degrees in longitude and latitude to reduce the influence from variations in atmospheric and geomagnetic shielding. The instrumentation consisted of tissue-equivalent proportional counters (TEPC) and a silicon diode spectrometer. Measurements were performed for 2 h to reduce the statistical uncertainties in the results. The TEPCs were evaluated either according to single-event analysis techniques or the variance-covariance method. Besides the total ambient dose equivalent, the instruments can be evaluated to reveal the low- and high-LET components. The EPCARD and FLUKA simulations can determine the contribution from each type of particle directly. The ratio between the calculated and the measured average value of the ambient dose equivalent rate was 1.00 +/- 0.08 with all instruments included for EPCARD and 0.97 +/- 0.07 when FLUKA was used. The measured high-LET component and the calculated neutron component are not quite identical, but should be similar. The agreement was always within 20%. The high-LET component contributed with about 57% at N57 E8 and 48% at N42 E12.
Radiation Protection Dosimetry 02/2007; 126(1-4):577-80. · 0.82 Impact Factor
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ABSTRACT: We describe microdosimetric measurements and simulations with Geant4 and FLUKA Monte Carlo codes in silicon and tissue. Analyses of deposited energy in sensitive volumes of some micrometers were carried out after exposure to heavy ion radiation
IEEE Transactions on Nuclear Science 01/2007; · 1.45 Impact Factor
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ABSTRACT: The aircrew exposure to cosmic radiation can be assessed by calculation with codes validated by measurements. However, the relationship between doses in the free atmosphere, as calculated by the codes and from results of measurements performed within the aircraft, is still unclear. The response of a tissue-equivalent proportional counter (TEPC) has already been simulated successfully by the Monte Carlo transport code FLUKA. Absorbed dose rate and ambient dose equivalent rate distributions as functions of lineal energy have been simulated for several reference sources and mixed radiation fields. The agreement between simulation and measurements has been well demonstrated. In order to evaluate the influence of aircraft structures on aircrew exposure assessment, the response of TEPC in the free atmosphere and on-board is now simulated. The calculated results are discussed and compared with other calculations and measurements.
Radiation Protection Dosimetry 02/2005; 116(1-4 Pt 2):327-30. · 0.82 Impact Factor
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ABSTRACT: The response of a tissue equivalent proportional counter (TEPC) has been simulated with the Monte Carlo transport code FLUKA. The absorbed dose distribution of lineal energy y has been determined for several monoenergetic photon and neutron sources. The agreement between the calculated results and the measurements carried out with different well-known sources is well demonstrated. Work is in progress in order to evaluate the response of the instrument in the cosmic ray environment.
Radiation Protection Dosimetry 02/2004; 110(1-4):833-7. · 0.82 Impact Factor
