intercomparison
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A simple hemispherical phantom has been designed and prepared for the EURADOS intercomparison exercise on (241)Am activity determination in the skull (2011-13). The phantom consists of three parts that substitute bone and soft tissues. (241)Am is deposited on the surfaces of the bone-substituting part. The design and assumed composition of phantom parts are discussed. A preparation of the voxel representation of the phantom is described. The spectrum of a real measurement of the physical phantom agrees well with the simulation. The physical phantom, and its voxel representation, is provided to the participants of the intercomparison exercise.
- MeSH
- americium analýza MeSH
- design vybavení MeSH
- fantomy radiodiagnostické MeSH
- fotony MeSH
- kalibrace MeSH
- kosti a kostní tkáň MeSH
- lebka účinky záření MeSH
- metoda Monte Carlo MeSH
- monitorování radiace metody MeSH
- počítačová rentgenová tomografie MeSH
- polyurethany chemie MeSH
- radiometrie metody normy MeSH
- reprodukovatelnost výsledků MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Česká republika MeSH
- MeSH
- analýza selhání vybavení MeSH
- hodnocení rizik MeSH
- lidé MeSH
- neutrony MeSH
- radiační ochrana metody MeSH
- radiometrie normy přístrojové vybavení MeSH
- únik radioaktivních látek MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- srovnávací studie MeSH
- Geografické názvy
- Česká republika MeSH
During the 7th European Conference on Protection Against Radon at Home and at Work held in the autumn of 2013 in Prague, the second intercomparison of measuring instruments for radon and its short-lived decay products and the first intercomparison of radon/thoron gas discriminative passive detectors in mix field of radon/thoron were organised by and held at the Natural Radiation Division of the National Radiation Protection Institute (NRPI) in Prague. In total, 14 laboratories from 11 different countries took part in the 2013 NRPI intercomparison. They submitted both continuous monitors for the measurement of radon gas and equivalent equilibrium radon concentration in a big NRPI chamber (48 m3) and sets of passive detectors including radon/thoron discriminative for the measurement of radon gas in the big chamber and thoron gas in a small thoron chamber (150 dm3).
- MeSH
- dceřiné produkty radonu analýza MeSH
- lidé MeSH
- mezinárodní spolupráce MeSH
- monitorování radiace přístrojové vybavení MeSH
- plyny analýza MeSH
- radiační ochrana přístrojové vybavení MeSH
- radioaktivní látky znečišťující vzduch analýza MeSH
- radon analýza MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
- Geografické názvy
- Česká republika MeSH
This paper discusses an intercomparison campaign performed in the mixed radiation field at the CERN-EU (CERF) reference field facility. Various instruments were employed: conventional and extended-range rem counters including a novel instrument called LUPIN, a bubble detector using an active counting system (ABC 1260) and two tissue-equivalent proportional counters (TEPCs). The results show that the extended range instruments agree well within their uncertainties and within 1σ with the H*(10) FLUKA value. The conventional rem counters are in good agreement within their uncertainties and underestimate H*(10) as measured by the extended range instruments and as predicted by FLUKA. The TEPCs slightly overestimate the FLUKA value but they are anyhow consistent with it when taking the comparatively large total uncertainties into account, and indicate that the non-neutron part of the stray field accounts for ∼30 % of the total H*(10).
- MeSH
- dávka záření * MeSH
- design vybavení MeSH
- Evropská unie MeSH
- kalibrace MeSH
- monitorování radiace přístrojové vybavení metody MeSH
- neutrony MeSH
- protony MeSH
- radiační ochrana přístrojové vybavení metody MeSH
- synchrotrony MeSH
- vystavení vlivu životního prostředí analýza MeSH
- Publikační typ
- časopisecké články MeSH
- srovnávací studie MeSH
During the Sixth European Conference on Protection Against Radon at Home and at Work held in autumn 2010 in Prague, the first intercomparison of continuous radon and its short-lived decay product monitors was organised and held by the Natural Radiation Division of the National Radiation Protection Institute (NRPI) in Prague. Eight laboratories submitted eight continuous radon monitors, two electronic monitors, three passive integral systems based on charcoal and three continuous radon short-lived decay product monitors. The intercomparison included exposures to both the radon gas concentration and equivalent equilibrium radon concentration (EEC) under different ambient conditions similar to the ones in dwellings. In particular, the influence of the equilibrium factor F, unattached fraction of EEC f(p) and absolute air humidity were investigated. The results of the radon gas measurements were performed on a calibration level of about 8 kBq m(-3). The results of all monitors were compared with the reference NRPI monitor.
- MeSH
- časové faktory MeSH
- lidé MeSH
- monitorování radiace přístrojové vybavení normy MeSH
- plyny analýza MeSH
- radiační ochrana přístrojové vybavení normy MeSH
- radioaktivní látky znečišťující vzduch analýza MeSH
- radon analýza MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
During the Eighth International Conference on High Levels of Natural Radiation and Radon Areas held in autumn 2014 at Prague, the third intercomparison of radon/thoron gas and radon short-lived decay products measurement instruments was organised by and held at the Natural Radiation Division of the National Radiation Protection Institute (NRPI; SÚRO v.v.i.) in Prague. The intercomparison was newly focussed also on continuous monitors with active sampling adapters capable to distinguish radon/thoron gas in their mix field.The results of radon gas measurements carried out in the big NRPI radon chamber indicated very well an average deviation of up to 5 % from the reference NRPI value for 80 % of all the exposed instruments. The results of equilibrium equivalent concentration continuous monitors indicated an average deviation of up to 5 % from the reference NRPI value for 40 % of all the exposed instruments and their ~8-10 % shift compared with the NRPI. The results of investigated ambient conditions upon response of exposed continuous monitors indicated influence of aerosol changes upon response of radon monitors with an active air sampling adapters through the filter, only. The exposures of both radon/thoron gas discriminative continuous monitors and passive detectors have been indicated inconsistent results: on one hand, their excellent agreement up to several per cent for both the gases, and on the other hand, systematic unsatisfactory differences up to 40 %. Additional radon/thoron exercises are recommended to improve both the instruments themselves and quality of their operators.
- MeSH
- dceřiné produkty radonu analýza MeSH
- design vybavení MeSH
- monitorování radiace přístrojové vybavení metody normy MeSH
- plyny analýza MeSH
- radiační pozadí * MeSH
- radioaktivní látky znečišťující vzduch analýza MeSH
- radiometrie přístrojové vybavení metody MeSH
- radon analýza MeSH
- reprodukovatelnost výsledků MeSH
- řízení kvality MeSH
- testování odbornosti laboratoří * MeSH
- Publikační typ
- časopisecké články MeSH
- hodnotící studie MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
- Geografické názvy
- Alžírsko MeSH
- Evropa MeSH
- Japonsko MeSH
- Spojené státy americké MeSH
Je obecně přijato, že celková nejistota pro sdělení předepsané dávky do cílového objemu při rádioterapii by neměla přesáhnout hodnotu 5 %. Přípustná nejistota pro přesnost výpočtu dávkové distribuce generované počítačovými plánovacími systémy pak nutně musí být ještě menší. V souladu s požadavky ICRU lze dávkovou distribuci vypočtenou plánovacím systémem považovat za dostatečně přesnou, pokud je relativní odchylka dávky vypočtené a dávky naměřené v určitém bodě na izodóze menší než 2 % v oblasti nízkého dávkového gradientu, resp. pokud je vzájemný posun bodů na vypočtené a naměřené izodózní křivce menší než 2 mm v oblasti s velkým dávkovým gradientem. Pro zjištění stavu kvality plánovacích systémů v CR bylo testováno 8 ze 27 systémů používaných v současné době v CR. Jejich porovnání bylo provedeno jednotnou metodou založenou na termoluminiscenčni (TLD) a filmové dozimetrii s využitím víceúčelového fantomu. Testy byly založeny na měření pro sedm typických ozařovacích geometrií: pravidelná pole, nepravidelná pole, pole s klíny, pole pro zakřivený povrch a pole s nehomogenitami. Absorbovaná dávka naměřená pomocí TLD bylá porovnávána s dávkou vypočtenou plánovacími systémy. Z výsledků je patrné, že mezi zkoumanými plánovacími systémy jsou určité rozdíly a že je v praxi obtížné vždy dodržet požadavky na přesnost specifikované ICRU. Ukázalo se, že navržená metoda měření pomocí víceúčelového fantomu je dobrým prostředkem pro nezávislou kontrolu plánovacích systémů, neboť poskytuje cennou informaci o konečné realizaci plánované rádioterapie.
The requirement of 5 % overall accuracy for the target-absorbed dose in radiotherapy implies that the accuracy of the relative dose calculation shoidd be only within a few percent. According to the recommendation of the International Commission on Radiation Units and Measurements (ICRU), a computer generated dose distribution is considered accurate enough if it differs from the results of relative dose measurements by less than 2%, or 2 mm in the position of isodose curves involving very steep dose gradients. Considering these requirements, eight treatment planning systems of 27 systems, currently used in Czech hospitals, were compared. The intercomparison was made using a multi-purpose phantom involving dose measurements based on thermoluminescent (TLD) and film dosimetry. Seven typical cases of irradiation were tested: regular fields, irregular fields, wedge fields, oblique incidence and non-homogenities. The absorbed dose measured by TLD was compared with the absorbed dose calculated by the treatment planning systems. The results indicate that the dose distributions generated by different treatment planning systems can differ from each other as well as from the measured dose distributions up to a level not acceptable in terms of the ICRU requirement. The method using the multipurpose phantom seems to be a good tool for regular independent quality control of the treatment planning systems since it shows the real dose outcome resulting from all procedures involved in the radiotherapy chain.
Computational models of acoustic wave propagation are frequently used in transcranial ultrasound therapy, for example, to calculate the intracranial pressure field or to calculate phase delays to correct for skull distortions. To allow intercomparison between the different modeling tools and techniques used by the community, an international working group was convened to formulate a set of numerical benchmarks. Here, these benchmarks are presented, along with intercomparison results. Nine different benchmarks of increasing geometric complexity are defined. These include a single-layer planar bone immersed in water, a multi-layer bone, and a whole skull. Two transducer configurations are considered (a focused bowl and a plane piston operating at 500 kHz), giving a total of 18 permutations of the benchmarks. Eleven different modeling tools are used to compute the benchmark results. The models span a wide range of numerical techniques, including the finite-difference time-domain method, angular spectrum method, pseudospectral method, boundary-element method, and spectral-element method. Good agreement is found between the models, particularly for the position, size, and magnitude of the acoustic focus within the skull. When comparing results for each model with every other model in a cross-comparison, the median values for each benchmark for the difference in focal pressure and position are less than 10% and 1 mm, respectively. The benchmark definitions, model results, and intercomparison codes are freely available to facilitate further comparisons.
An international comparison of continuous monitors measuring radon activity concentration was performed to validate the traceability of the European radon calibration facilities. It was carried out by comparing the secondary standards used by these previous facilities, ranging from 100 Bq·m-3 to 300 Bq·m-3. Secondary standards were individually compared to a secondary reference device previously calibrated in a reference radon atmosphere traceable to a primary standard. The intercomparison was organized by the National Institute for Nuclear, Chemical, and Biological Protection (SUJCHBO) in the period from October 2019 to April 2020 within the European Metrology Program for Innovation and Research (EMPIR), JRP-Contract 16ENV10 MetroRADON. Eight European laboratories participated in this study. The results of the experiment are presented and discussed.
