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Sample records for air kerma index

  1. Evaluation of entrance surface air kerma from exposure index in computed radiography

    International Nuclear Information System (INIS)

    The aim of this study was to establish an indirect method to calculate the values of entrance surface air kerma in patients undergoing diagnostic examinations in X-ray systems with computed radiography based on the exposure index. The entrance surface air kerma values were compared with values obtained also indirectly based on measurements of X-ray tube output. The mean±standard deviation (1?) and third quartile for entrance surface air kerma calculated from the exposure index were 2.1±1.0 mGy and 3.0 mGy, respectively. For entrance surface air kerma based on measurements of the X-ray tube output, the mean±standard deviation (1?) and third quartile were respectively 3.1±1.9 mGy and 5.5 mGy. The observed values of entrance surface air kerma are smaller than the reference level adopted in Brazil (10 mGy). The results obtained with both methods were similar when taking into account the estimated uncertainties in the determination of air kerma values, although the reproducibility of the determinations based on the exposure index is better. - Highlights: • Indirect method to calculate entrance surface air kerma in computed radiography. • Method based on the exposure index for digital radiography. • Comparison with an indirect method based on measurements of X-ray tube output

  2. Volume computed tomography air kerma index and image quality evaluation in Brazil

    International Nuclear Information System (INIS)

    The aim of this study was to evaluate the image quality of 29 computed tomography (CT) scanners in Brazil and to perform estimations of patient dose and image quality of common CT examinations at these equipment. The volume CT air kerma indexes (C VOL) were estimated, using normalised weighted air kerma indexes, supplied by the ImPACT group. The image quality tests were performed using the phantom and accreditation protocol from the American College of Radiology (ACR). The C VOL values for head scans varied between 8.7 and 108 mGy. The Hi-res chest examinations presented C VOL values varying from 0.4 to 32 mGy. For abdominal scans, the estimated C VOL values varied between 4.1 and 94 mGy. This wide variation of air kerma between different centres is related to the scanner type and also to the scanning parameters. The results also showed that the image quality did not attend all ACR CT accreditation requirements. (authors)

  3. Image quality and volume computed tomography air kerma index (Cvol) evaluation in Recife

    International Nuclear Information System (INIS)

    The Computed Tomography (CT) is an important diagnostic imaging method, widely used. However, in spite of all the advantages and technologic advances within the CT scanners, the tomographic procedures result in high absorbed doses to patients. The main objective of this work was to perform a dosimetric study of CT scanners located at Recife and to evaluate the image quality on CT examinations in these equipment. The volume CT air kerma index (CVOL) and air kerma length product (PKL,CT) were estimated. These values were calculated using normalized weighted air kerma indexes in CT standard dosimetry phantoms (nCW), supplied by ImPACT group for several CT scanners, and the scan parameters of routine head, routine chest and hi-resolution chest CT exams performed at 20 institutions. The irradiation parameters of 15 adult patients for each CT procedure were registered at six participating centres, at which the phantom from the American College of Radiology (ACR) CT accreditation protocol was used for the image quality measurements. For routine head exams, the CVOL values varied between 12 and 58 mGy (at the posterior fossa) and 15 to 58 mGy (at the cerebrum) and the PKL,CT, from 150 to 750 mGy·cm. The CVOL values for routine chest procedures varied from 3 to 26 mGy and the PKL,CT, between 120 and 460 mGy·cm. In relation to Hi-resolution chest exams, CVOL values were from 1.0 to 2.7 mGy and the PKL,CT values varied between 24 and 67 mGy·cm. The image quality evaluations results showed that almost all scanners presented at least one inadequacy. One of the equipment presented faults at 70% of the tests. With regard to the image noise, only two scanners presented acceptable results. From these results, it is possible to conclude that the volume CT air kerma index values are lower than the European reference levels. However, the image quality of these CT scanners does not attend the ACR requirements, suggesting the need to implement quality assurance programs at the evaluated institutions. (author)

  4. Image quality and volume computed tomography air kerma index (C{sub vol}) evaluation in Recife; Avaliacao da qualidade de imagem e do indice volumetrico de Kerma ar em tomografia computadorizada (C{sub vol}) em Recife

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, Marcos Ely Almeida

    2008-07-01

    The Computed Tomography (CT) is an important diagnostic imaging method, widely used. However, in spite of all the advantages and technologic advances within the CT scanners, the tomographic procedures result in high absorbed doses to patients. The main objective of this work was to perform a dosimetric study of CT scanners located at Recife and to evaluate the image quality on CT examinations in these equipment. The volume CT air kerma index (C{sub VOL}) and air kerma length product (P{sub KL,CT}) were estimated. These values were calculated using normalized weighted air kerma indexes in CT standard dosimetry phantoms ({sub n}C{sub W}), supplied by ImPACT group for several CT scanners, and the scan parameters of routine head, routine chest and hi-resolution chest CT exams performed at 20 institutions. The irradiation parameters of 15 adult patients for each CT procedure were registered at six participating centres, at which the phantom from the American College of Radiology (ACR) CT accreditation protocol was used for the image quality measurements. For routine head exams, the C{sub VOL} values varied between 12 and 58 mGy (at the posterior fossa) and 15 to 58 mGy (at the cerebrum) and the P{sub KL,CT}, from 150 to 750 mGy{center_dot}cm. The C{sub VOL} values for routine chest procedures varied from 3 to 26 mGy and the P{sub KL,CT}, between 120 and 460 mGy{center_dot}cm. In relation to Hi-resolution chest exams, C{sub VOL} values were from 1.0 to 2.7 mGy and the P{sub KL,CT} values varied between 24 and 67 mGy{center_dot}cm. The image quality evaluations results showed that almost all scanners presented at least one inadequacy. One of the equipment presented faults at 70% of the tests. With regard to the image noise, only two scanners presented acceptable results. From these results, it is possible to conclude that the volume CT air kerma index values are lower than the European reference levels. However, the image quality of these CT scanners does not attend the ACR requirements, suggesting the need to implement quality assurance programs at the evaluated institutions. (author)

  5. Development of a phantom and a methodology for evaluation of depth kerma and kerma index for dental cone beam computed tomography

    International Nuclear Information System (INIS)

    Basically, all modalities of diagnostic radiology require phantoms suitable for dosimetric evaluations. New technologies frequently arise unaccompanied of tools for dosimetric evaluations and quality control. In this study, a low-cost phantom and a consequent proposed methodology for dosimetric evaluations in cone beam computed tomography (CBCT) were presented. The developed phantom has typical dimensions of the human face, was built in polymethyl methacrylate and filled with water. Three devices with different technological concepts were evaluated and a proposed index, kerma index-height product (PKIH), was defined as an option to the use of air kerma-area product. The results of this study show relatively uniform kerma profiles for scanners with field of views (FOVs) of large diameters and non-uniform for FOVs of small diameters. With regard to the values obtained for the kerma indexes, much higher values were found for the equipment FOVs with small diameter compared with the values of the two other equipment that have larger diameters. The results indicate that (1) there is a need for special phantoms for use in CBCT, (2) the use of PKA in the evaluation of protocols on different equipment can lead to false interpretations and (3) the new index is a suitable alternative for the use of PKA in CBCT. (authors)

  6. Recent developments and current status of air kerma standards

    International Nuclear Information System (INIS)

    Primary Standard Dosimetry Laboratories (PSDL) usually maintain air kerma standards for kilovoltage x-rays (10 kV to 300 kV) and for 137Cs- and 60Co-? radiation. Free-air ionisation chambers (FAC) and cavity ionisation chambers are used as primary air kerma standards for kilovoltage x-rays and for 137Cs- and 60Co-? radiation, respectively. The majority of the National Metrology Institutes (NMIs) signed the Mutual Recognition Arrangement (MRA) of national measurement standards and of calibration and measurement certificates issued by NMIs. The MRA has been available for signature since 14th October 1999. According to the MRA, the signatories participate in CIPM key comparisons executed by the Consultative Committees or the BIPM, leading to a key comparison reference value. The degree of equivalence of a national measurement standard is expressed quantitatively in terms of its deviation from the key comparison reference value and the uncertainty of this deviation. For air kerma standards the Consultative Committee for Ionising Radiation (CCRI(I)) currently maintains three types of key comparisons and a so-called supplementary comparison. The air kerma key comparisons are organised bilaterally and are carried out between the air kerma standards of the BIPM and the participating NMIs. The radiations used are low-energy (10 kV to 50 kV) and medium energy (100 kV to 250 kV) x-ray beams and 137Cs- and 60Co-? radiation. To be entitled to enter the key comparison database with respect to air kerma an NMI has to participate in a key comparison within a time period of 10 years. In keeping with the longstanding method of presenting the data, the CCRI(I) took the decision at its meeting in 1999 to use the BIPM determination of air kerma rate as the key comparison reference value. For this reason the BIPM air kerma standards are of special importance. Due to the fact that the air kerma key comparisons have been conducted on an ongoing basis since 1966 for low-energy x-rays and since 1975 for medium-energy x-rays and 60Co-? radiation the results represent an invaluable database which can be regarded as an indicator of the status of the air kerma standards operated worldwide. Consequently, this database and the reports of the NMIs to the CCRI(I) meetings which take place periodically every two years were used for the current status report as an essential source of information. Because different techniques are used to measure the air kerma rate of kilovoltage x-rays and 137Cs- and 60Co-? radiation this status report is divided in this two parts. Undoubtedly, the most important new development was the re-evaluation of several correction factors required for cavity ionization chamber standards. However, there were also interesting developments using Monte Carlo techniques and spectrometry for the determination of x-ray quality dependent correction factors of FACs

  7. Kerma determination in air on mamma by thermoluminescence

    International Nuclear Information System (INIS)

    In this work the experimental results of the entrance exposition are shown and Kerma in air [mGy] in mamma obtained by irradiation of accreditation phantom of American College of Radiology (ACR). The irradiations were realized in a conventional mammography equipment of Hospital Juarez in Mexico; the technique used during the irradiations was of automatic exposition; the thickness for the phantom ACR obtained by the technique were of 4.2 and 4.5 cm; the kilo voltage pick was of 24 kVp, the time and the milli amperage per second variable. The measuring of Kerma in air was obtained with thermoluminescent dosemeters of solid state, of nano particles of zirconium dioxide prepared by the precipitation method. The dosemeters were homogenized previously in low energies of X-rays that are those used for mammography. The thermoluminescent dosemeters of ZrO2 were calibrated by means of an ionization chamber for different expositions. The calibration curve is reported for the exposition and Kerma in air against thermoluminescent intensity obtained by reading of thermoluminescent dosemeters of ZrO2, as well as the technique employee for the Kerma determination in air and entrance exposition in mamma. (Author)

  8. Kerma determination in air on mamma by thermoluminescence; Determinacion de Kerma en aire en mama por termoluminiscencia

    Energy Technology Data Exchange (ETDEWEB)

    Palacios P, L. L.; Rivera M, T. [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Av. Legaria 694, 11500 Mexico D. F. (Mexico)], e-mail: lpalaciop@ipn.mx

    2009-10-15

    In this work the experimental results of the entrance exposition are shown and Kerma in air [mGy] in mamma obtained by irradiation of accreditation phantom of American College of Radiology (ACR). The irradiations were realized in a conventional mammography equipment of Hospital Juarez in Mexico; the technique used during the irradiations was of automatic exposition; the thickness for the phantom ACR obtained by the technique were of 4.2 and 4.5 cm; the kilo voltage pick was of 24 kV{sub p}, the time and the milli amperage per second variable. The measuring of Kerma in air was obtained with thermoluminescent dosemeters of solid state, of nano particles of zirconium dioxide prepared by the precipitation method. The dosemeters were homogenized previously in low energies of X-rays that are those used for mammography. The thermoluminescent dosemeters of ZrO{sub 2} were calibrated by means of an ionization chamber for different expositions. The calibration curve is reported for the exposition and Kerma in air against thermoluminescent intensity obtained by reading of thermoluminescent dosemeters of ZrO{sub 2}, as well as the technique employee for the Kerma determination in air and entrance exposition in mamma. (Author)

  9. Recent developments and current status of air kerma standards

    International Nuclear Information System (INIS)

    The current status of air kerma standards for kilovoltage X rays and for 137Cs and 60Co gamma radiation maintained at primary standards dosimetry laboratories is reviewed using results of the bilateral key comparisons between the air kerma standards of the Bureau international des poids et mesures (BIPM) and those of national metrology institutes. Owing to the re-evaluation of kwall and kan, which are the correction factors for wall effects and axial beam non-uniformity for cavity ionization chambers, respectively, a significant increase of about 0.8% in the realization of the gray for air kerma in both 137Cs and 60Co fields is to be expected. A consistent set of free air chamber correction factors for electron loss, photon scatter, fluorescence and bremsstrahlung was calculated at the BIPM using state of the art Monte Carlo methods for all free air chamber standards in use worldwide. Consistent use of this set by all national metrology institutes would further improve the degree of equivalence of free air chamber standards. (author)

  10. Evaluation of entrance surface air kerma in pediatric chest radiography

    International Nuclear Information System (INIS)

    The objective of this study was to evaluate the entrance surface air kerma in pediatric chest radiography. An evaluation of 301 radiographical examinations in anterior–posterior (AP) and posterior–anterior (PA) (166 examinations) and lateral (LAT) (135 examinations) projections was performed. The analyses were performed on patients grouped by age; the groups included ages 0–1 y, 1–5 y, 5–10 y, and 10–15 y. The entrance surface air kerma was determined with DoseCal software (Radiological Protection Center of Saint George's Hospital, London) and thermoluminescent dosimeters. Two different exposure techniques were compared. The doses received by patients who had undergone LAT examinations were 40% higher, on average, those in AP/PA examinations because of the difference in tube voltage. A large high-dose “tail” was observed for children up to 5 y old. An increase in tube potential and corresponding decrease in current lead to a significant dose reduction. The difference between the average dose values for different age ranges was not practically observed, implying that the exposure techniques are still not optimal. Exposure doses received using the higher tube voltage and lower current-time product correspond to the international diagnostic reference levels. - Highlights: • The entrance surface air kerma of chest X-ray examinations in pediatric patients was estimated. • The data were analyzed for patients aged up to 15 y, stratified by age. • The doses of LAT examinations were 40% higher than of AP/PA because of kV used. • An increase in kV with a decrease in mAs leads to significant dose reduction

  11. Air kerma rates measurement in an interventional cardiology suite

    International Nuclear Information System (INIS)

    In Interventional Cardiology (IC), the assessment of the radiation that the physicians are exposed to is extremely important because the irradiation is not uniform and the received doses are substantially high. During the procedure, the radiation control is complex and there are several reasons for the high exposure levels. It is necessary to perform dosimetric assessments in different parts of the physicians' body and in different specific points of the examination room. By analyzing this information it is possible to determine the probable causes and to provide recommendations, aiming at optimizing the radiological protection. This work had the following objectives: to assess the exposition levels at representative points of critical anatomical regions of the physicians' body who perform IC examinations; to provide means to implement personal monitoring procedures; and to make them aware of the radiation risks. Measurements of air kerma rates were performed in 45 points around the examination table, along the room. Such measurements were made in the conditions frequently used in coronary angiography and coronary angioplasties procedures: adult patient phantom; RAO, LAO and AP incidences; fluoro and digital modes; 13cm and 17cm magnification modes; frequencies of 30f/s (fluoro) and 15 f/s (digital); typical field size used during examinations. Data were obtained at the lenses, chest, hands, gonads and knees levels. For AP incidence, the lowest contributions for scattered radiation and a more homogeneous distribution of radiation were observed. The highest air kerma rates were obtained during digital acquisition mode and for LAO incidence on interventional radiologists, anaesthesists and nurses. The most critical anatomical regions were the knees and gonads. Air kerma rates of about 7,8mGy/h were registered in some places. At physicians' hands position, rates of about 5mGy/h were reached. In several points and levels measured (workload ∼ 6 examinations/day), this air kerma rates would produce a higher dose than the annual limits. This work shows the need to implement additional protection devices; to elaborate safety guidelines; to train staff on radiological protection, and to implement the use of additional dosemeters attached to critical points. (author)

  12. Status of air kerma and absorbed dose standards in India

    International Nuclear Information System (INIS)

    Full text: The Radiation Safety Systems Division of Bhabha Atomic Research Centre, India maintains Primary and Secondary Standards of various parameters of radiation measurements and provides calibration services to various users of radiation in the country. This is an apex laboratory in India and plays a pivotal role in ensuring accurate radiological measurements. The laboratory coordinates national intercomparisons of radiation measurements to maintain their uniformity and traceability and is linked through various programmes with the other International organizations such as Bureau Internationale des Poids et Mesures (BIPM) Paris, International Atomic Energy Agency (IAEA) Vienna, Asia Pacific Metrology Programme (APMP) Taiwan. It is the recognized Regional Secondary Standards Dosimetry Laboratory (SSDL) of IAEA/WHO (World Health Organisation). This paper brings out the status of various primary and secondary standards for radiological measurements maintained at BARC. 1. Primary Exposure/Air-kerma standard at Co-60 energy (therapy level): The primary standard for exposure/ air-kerma measurements maintained at BARC is a graphite cavity chamber of volume 4.362 cc with an internal diameter of 1.8 cm, internal height of 1.78 cm and wall thickness of 704.3mg/cm2. Correction factors for the difference between electron stopping powers, photon mass energy absorption coefficients of air and graphite wall, correction for recombination, radiation field non-uniformity, stem scatter and polarity effect are applied and the maximum overall uncertainty in the realisation of exposure/air-kerma is around ±1%. This standard has been intercompared with IAEA and BIPM through transfer standard and the agreement in the results are better than ±1%. An intercomparison under the APMP programme is to be held during May, 2002. 2. Primary Exposure/Air-kerma standard at protection and brachytherapy level: A set of three spherical graphite-walled cavity chambers of different air-volumes are maintained as primary standards for protection level and brachytherapy measurements of Ir-192, Cs-137 and Co-60 sources. These chambers are made of high purity reactor-grade graphite of density 1700 kg/m3. The three chambers have different wall thickness, the external diameters of all the chambers being equal. A reference standard in the form of a re-entrant chamber developed at BARC, calibrated against this primary standard was intercompared with a reference standard from M.D Anderson Centre, Houston, U.S.A and the results showed a good agreement. Recently one of the chambers was used for the Cs-137 intercomparison with IAEA and showed an agreement of better than ± 1%. 3. Primary Standard for X-rays - the free air chamber (FAC): This facility is utilized in conjunction with a Philips RT-250 X-ray machine for calibrating secondary standard dosemeters at different X-ray qualities in the 75 to 250 kV range. The total uncertainty in the realization of air kerma is around ±1% using the free air chamber. Accuracy of calibration of the secondary standards is estimated to be better than ±2%. The FAC has been intercompared via transferable transfer standards with FACs at BIPM (1971), BNM (France) RCL (Canada) and Kriss (Korea), which showed good agreement within ±1% after necessary correction for the spectral differences in X-ray beams. BARC is just now taking part in intercomparisons of X-ray air kerma calibration factors organised by Institute of Nuclear Energy Research (INER), Taiwan under Asia Pacific Metrology Programme. In addition to the above-mentioned primary standards, the SSDL is also maintaining the following secondary standards. For air kerma measurements at Co-60 gamma energy, ionisation chambers of Exradin A3, NE2571, NE2577 and Victoreen 415 types are calibrated and maintained. For Co-60 radiation dose to water measurements, NE 2571 and NE 2577 chambers calibrated at BIPM in terms of ND,W are maintained. For air kerma at medium energy x-rays, chambers of the type Exradin A2, NE 2571, NE2577, Victoreen 415 B, Victoreen 415, Exradin A3 and NE 2581 are maintained. These chambers have been calibrated against the primary standards and have been used in the international intercomparison experiments. The future programme of development of standards include i) Development of graphite/water calorimeters as absorbed dose standards, ii) Establishment of extrapolation chamber as primary standard for absorbed dose for beta and soft x-ray beams and iii) Development of energy-independent plastic scintillators as reference standard for low energy low activity brachytherapy sources. (author)

  13. Comparison of air kerma measurements in mammography using thermoluminescent dosimeters

    International Nuclear Information System (INIS)

    A co-ordinated research project, Image Quality and Patient Dose Optimization in Mammography in Eastern European Countries, was conducted by the IAEA, which aimed at defining a methodology for the implementation of a quality assurance programme in mammography and at exercising the assessment of image quality and patient doses in a sample of hospitals in eastern European countries.A comparison of dosimetry systems has been organized to ensure that dose measurements carried out within the framework of the project are comparable. Selected mammography units from the Czech Republic, Hungary, Poland, Romania, Slovakia and Spain participated in the exercise. The thermoluminescence method was selected for the comparison. The dosimeters were irradiated free in air to values of air kerma in the range of 5 mGy to 9 mGy and mailed to the participants for evaluation. Deviations of measured values from the true values of less than 10% were considered a measure of good dosimetry performance. The results of the comparison showed that about 70% of reported values of air kerma were outside the 10% acceptance limit. Two follow-up exercises were organized. The first follow-up resulted in only 20% of reported values exceeding the limit, and during the second follow-up all results were within the acceptance limit

  14. Portable radiation meters evaluation in high rates of air kerma

    Energy Technology Data Exchange (ETDEWEB)

    Damatto, Willian B.; Potiens, Maria da Penha A.; Vivolo, Vitor, E-mail: wbdamatto@ipen.br, E-mail: mppotiens@ipen.br, E-mail: vivolo@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2015-07-01

    A set of portable meters of ionizing radiation high rates of air kerma (teletectors) commonly used in emergencies in Brazil and sent to the Calibration Laboratory of IPEN were under several tests and analyst is parameters for the detectors behavior were established, specifying their sensitivities and operating characteristics. Applied tests were: reading equipment variation with battery voltage, geotropism effect, energy dependence, the angular dependence and overload. Thus it was possible to determine the most common characteristic found in these equipment (quality control programs). The behavior of 17 portable meters was analyzed and in this study, 10 of them have been tested. It was performed to characterize the gamma irradiating system (radiation dosimetry field) that possesses higher activity in teletectors for testing of larger measuring range. New calibration criteria were established following international recommendations. Therefore, it was made the improvement of the quality control programme of portable meters of ionizing radiation high rates of air kerma calibration laboratory, benefiting the users of such equipment with better consistent calibration measurements. (author)

  15. Routine measurement of gamma ray air kerma rate in the environment

    International Nuclear Information System (INIS)

    This Note, issued by Her Majesty's Inspectorate of Pollution, provides technical guidance on the routine measurement of gamma ray air kerma rate in the environment. It includes a protocol for the measurement, interpretation and reporting of environmental gamma ray air kerma rates and appendices reviewing existing techniques, instruments, calibration facilities and the physics of such measurements. (UK)

  16. Comparison of the NIST and ENEA air kerma standards

    International Nuclear Information System (INIS)

    A comparison was made between the National Institute of Standards and Technology (NIST) and Ente per le Nuov Tecnologie l'Energia e l'Ambiente (ENEA) air kerma standards for medium energy x rays and 60Co gamma rays. The comparison took place at ENEA in June 1994. Two different transfer chambers from NIST were used for the comparison. The measurements were made at radiation qualities similar to those used at the Bureau International des Poids et Mesures (BIPM) (generating voltages of 100 kV, 135 kV, 180 kV and 250 kV, respectively) and with 60Co gamma radiation. The transfer chamber calibration factors obtained at the NIST and at the ENEA agreed with one another to 0.03% for 60Co gamma radiation and between 0.1% to 0.8% for the medium energy x-ray beam codes

  17. X-rays spectrum and air Kerma during a mammography study; Espectro de los rayos X y Kerma en aire durante un estudio mamografico

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez G, J. [Instituto Nacional de Estadistica Geografia e Informatica, Av. Heroes de Nacozari Sur 2301, Fracc. Jardines del Parque, 20276 Aguascalientes (Mexico); Hernandez V, R.; Hernandez D, V. M.; Vega C, H. R. [Unidad Academica de Estudios Nucleares, Universidad Autonoma de Zacatecas, Cipres 10, Fracc. La Penuela, 98068 Zacatecas (Mexico)], e-mail: fermineutron@yahoo.com

    2009-10-15

    In this calculation series was modeled the source of electrons, the target and the filter. Using thermoluminescent dosemeters of ZrO{sub 2}+PTFE the air Kerma was measured in five points located on a phantom made with acrylic and water when it was exposed to a X-rays beam produced by electrons of 24 KeV and 10 m A of current that produces a mammography. The air Kerma values at the entrance surface of the phantom were compared with values calculated by Monte Carlo methods. The air Kerma values measured indicate that approximately the five points receive the same air Kerma, what means that the beam is homogeneous, of the Monte Carlo calculations we find that the center receives a greater dose what implies that the beam is not uniform, the explanation of this fact is attributed to was used a simple model in the calculations, nevertheless, the air Kerma average measured at the entrance surface of the phantom was of 0.96 +{sub -} 0.03 m G, while the other obtained by the calculations was of 0.96 +{sub -} 0.06 mGy, to compare both do not exist significant differences. (author)

  18. Evaluation and test of 192Ir air kerma strength for afterloading systems

    International Nuclear Information System (INIS)

    Objective: To study the method of measuring air kerma strength of afterloading units with 192Ir source by using well type ionization chamber. Methods: The air kerma strength of 30 afterloading units with 192Ir source was measured using 2000A electrometer and 1000 plus well type ionization chamber, and apparent activity of the source was calculated with the air kerma strength and apparent activity conversion factor. The measured activity of the source was compared with the original value of the source provided by the manufacturer, and the relevant deviation should be within ±5%. Results: The air kerma strength of afterloading units with 192Ir sources was tested. The relevant deviation of the measured activity and the original value was within -0.1%-4.4%. Conclusions: The measurement method with a well type ionization chamber is convenient and highly accurate which can be used for the test of quality control in hospitals. (authors)

  19. Comparison of the air kerma standards of the NRC and the BIPM 60Co γ rays

    International Nuclear Information System (INIS)

    A comparison of the standards for air kerma of the National Research Council of Canada and of the Bureau International des Poids et Mesures has been carried out in 60Co gamma radiation. The results show that the NRC and the BIPM standards for air kerma are in agreement, yielding a ratio of 1.0020 for the calibration factors of the transfer chambers, the difference from unity being within the combined standard uncertainty of 0.0031. (authors)

  20. Factor kerma decrease for interactions X and gamma rays with air, water, polyethylene and plexiglass

    International Nuclear Information System (INIS)

    KERMA decrease caused by secondary particle energy loss in air, water, polyethylene and plexiglass in 0.5 MeV to 10 MeV region of X and gamma-photons, is presented in this paper. The calculations of KERMA factor decrease are made for Compton, photo effects and pair production effects by incident X and gamma rays, in the mentioned energy interval. (author)

  1. Realization of reference air-kerma rate for low-energy photon sources

    International Nuclear Information System (INIS)

    A large air-filled parallel-plate extrapolation chamber with thin graphite front and back electrodes is used as a primary standard measuring device for low-energy interstitial brachytherapy sources from which the unit of air-kerma strength or reference air-kerma rate can be derived. The chamber is suitable for low-energy photons with energies up to 40 keV. The underlying principle is that the air-kerma rate at a given point is proportional to the increment of ionization per increment of chamber volume at chamber depths greater than the range of secondary electrons originating from the electrode. The fundamentals for evaluating the extrapolation curves are presented as well as a detailed description of the present set-up of the P.T.B. large-volume extrapolation chamber (G.R.O.V.E.X.). Comparisons between the G.R.O.V.E.X. and other primary standards for air-kerma and reference air-kerma rate are presented. (authors)

  2. X-rays spectrum and air Kerma during a mammography study

    International Nuclear Information System (INIS)

    In this calculation series was modeled the source of electrons, the target and the filter. Using thermoluminescent dosemeters of ZrO2+PTFE the air Kerma was measured in five points located on a phantom made with acrylic and water when it was exposed to a X-rays beam produced by electrons of 24 KeV and 10 m A of current that produces a mammography. The air Kerma values at the entrance surface of the phantom were compared with values calculated by Monte Carlo methods. The air Kerma values measured indicate that approximately the five points receive the same air Kerma, what means that the beam is homogeneous, of the Monte Carlo calculations we find that the center receives a greater dose what implies that the beam is not uniform, the explanation of this fact is attributed to was used a simple model in the calculations, nevertheless, the air Kerma average measured at the entrance surface of the phantom was of 0.96 +- 0.03 m G, while the other obtained by the calculations was of 0.96 +- 0.06 mGy, to compare both do not exist significant differences. (author)

  3. Attenuation effects on the kerma rates in air after cesium depositions on grasslands

    International Nuclear Information System (INIS)

    Since the reactor accident of Chernobyl, cesium depth profiles and nuclide-specific kerma rates in air have been determined for various grassland sites in south Bavaria and in Ukraine. The sites are described by soil characteristics, annual precipitation, distance from release point, mode of deposition, and activity per unit area. The effects of surface roughness and migration of cesium into the soil on the kerma rate in air over grasslands was determined by two methods. The kerma rates in air obtained by the evaluations of in situ gamma-ray spectrometry results and of measured activity distributions in the soil showed only negligible differences for the observation period of 6 years after deposition. for the sites in Ukraine the kerma rate in air per activity per unit area was found to be systematically 40% higher than in Bavaria. The results from Bavaria on the attenuation of the kerma rate and a data set, including experiences from the weapons test fallout, are analytically approximated as a function of time up to 25 years after deposition. (orig.)

  4. Comparative study of Brazilian and North American unshielded primary air kerma of radiological equipment

    International Nuclear Information System (INIS)

    The philosophy of shield design in diagnostic radiology has changed in recent years, due to the more restrictive dose limits to workers and public adopted in various countries. According to report 147 of the National Council of Radiation Protection and Measurements (NCRP 147, 2004), the structural shielding design is based on the quantity of unshielded primary air kerma, measured at the distance of one meter. Due to the fact that air kerma presents a strong dependent on the workload and output of the x-ray tube, NCRP 147 provides reference values for these parameters, all of them based on North-American clinical routine. The present work surveyed Brazilian values of workload, patient workflow and X-ray tube output, in order to estimate the unshielded primary air kerma at one meter for different diagnostic modalities

  5. Evaluation of the air kerma rates stability used in diagnostic radiology calibration

    International Nuclear Information System (INIS)

    The objective of this work was to perform tests in order to evaluate the stability of the air kerma rates measured with the dosimetric reference system of the calibration laboratory of IPEN (LCI)). The diagnostic radiology reference system consists of a parallel plates ionization chamber with volume of 1cm3, PTW, model 77334, connected to a PTW electrometer, model UNIDOS, type 10001, and it is used a 14C as check source. This parallel plate ionization chamber can be also used for radiography and fluoroscopy modes measurements during the characterization of the diagnostic radiology beams. The air kerma rates obtained during the calibration measurements were are evaluated from 2005 to 2007. (author)

  6. X-Rays spectrum and air kerma during a mammography study;Espectro de los rayos X y kerma en aire durante un estudio mamografico

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez G, J. [Instituto Nacional de Estadistica Geografia e Informatica, Direccion General de Innovacion y Tecnologia de Informacion, Av. Heroes de Nacozari Sur No. 2301, Fracc. Jardines del Parque, 20276 Aguascalientes (Mexico); Hernandez V, R.; Chacon R, A.; Vega C, H. R., E-mail: ramirezgonzalezjaime@yahoo.com.m [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Calle Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico)

    2009-10-15

    The X-rays spectrum produced in a mammography has been calculated by means of Monte Carlo methods. In this calculation series it is modeled the electrons source, the target and the filter. The spectra were calculated for an energy of the electrons of 28 keV and for targets of W, Mo and Rh. The calculations extended to analyze the effect that produces the filters inclusion in the spectra; the spectra of W-A1, Rh-Rh, Mo-Mo, Mo-Rh and Mo-Be were calculated this way. Using thermoluminescent dosemeters of ZrO{sub 2}+PTFE the air kerma was measured in five points located on a phantom made with acrylic and water when it is was exposed to a X-rays beam produced by electrons of 24 keV and 10 m A of current that it produces a mammography. The values of the air kerma on the entrance surface of the phantom were compared with the calculated values by means of Monte Carlo methods. The calculated spectra present a continuous component and another discreet and its form is similar to the reported spectra in the literature. The filters inclusion allows the elimination of the low energy photons that do not have utility in the obtaining of the mammography image and only they contribute to deposit a dose in the mamma. The values of the measured air kerma indicate that the five points receive the same air kerma approximately, what means that the beam is homogeneous, of the Monte Carlo calculations we find that the center receives a bigger dose which implies that the beam is not uniform, the explanation on this fact it is attributed to that a simple model was used in the calculations, nevertheless, the average of the air kerma measured on the entrance surface of the phantom was of 0.96 +- 0.03 m G, while the obtained by means of the calculations was of 0.96 +- 0.06 mGy, when comparing both significant differences do not exist. (Author)

  7. Changes to the air-kerma standards of the BIPM and primary standards dosimetry laboratories: Implications for IAEA calibrations to SSDL members

    International Nuclear Information System (INIS)

    Worldwide alterations in air-kerma standards have taken lace in the past. For example, national air-kerma standards were changed in the late eighties by about 1% due o changes in the internationally agreed underlying physical data. More recently, several Primary Standards Dosimetry Laboratories (PSDLs) have altered their primary standards of air kerma. This paper reviews these changes and the implications for the air-kerma standards maintained y the IAEA

  8. Air kerma rate constants for gamma emitters used most often in practice

    International Nuclear Information System (INIS)

    It is often required to estimate the dose rate at a distance from radionuclides that are sources of X rays and gamma rays. Such calculations may be required for planning radiation protection measures in the vicinity of radioactive sources or patients containing radionuclides, calibrations of radiation instruments or for estimating the absorbed dose rate to patients receiving brachytherapy. The factor relating activity and air kerma rate is called air kerma rate constant - ?o-bar. In this paper, the results of recalculation of this quantity for unfiltered point sources of radionuclides in practice used most often are given. The calculations included corrections for internal conversion of X rays and gamma rays and detailed accounting of the generation of the K and L series X rays from internal conversion and electron capture. Particular air kerma rate constants were calculated for each discrete line in the photon spectrum of radionuclide with a yield per decay event >0.01% and the energy >20 keV. Since the energy structure of the photon spectra and accessible discrete numerical values of the mass energy-transfer coefficient for air are not the same, the cubic spline interpolation was used to obtained the coefficient, where the photon spectrum data are available. In the calculation, the latest gamma ray spectral data for all radionuclides and latest data for the mass energy-transfer coefficient for air are used. Air kerma rate constants for the following 35 radionuclides are calculated: 11C, 13N, 15O, 18F, 24Na, 42K, 43K, 51Cr, 52Fe, 59Fe, 57Co, 58Co, 60Co, 67Ga, 68Ga, 75Se, 99Mo, 99mTc, 111In, 113mIn, 123I, 125I, 131I, 127Xe, 133Xe, 137Cs, 152Eu, 154Eu, 170Tm, 182Ta, 192Ir, 197Hg, 198Au, 201Tl and 241Am. (authors)

  9. Product estimate of air kerma-area and the air kerma in the input surface of the skin of pediatric patients undergoing chest X-ray

    International Nuclear Information System (INIS)

    The aim of this paper is to evaluate the entrance air kerma (Ka,e) and the product air kerma-area (Pka) for chest examinations performed with pediatric patients in a large public hospital of Recife. For this study 89 examinations of patient with ages from zero to 10 years old were evaluated. The results showed that the mean Ka,e values, for patients of 0-1 years old, 1-5 years old and 5-10 years old, were, respectively, 100 mGy, 120 mGy and 100 mGy. The Pka values for newborn patients range from 11,9 to 58,4 mGy.cm2, for patients with 1 to 5 years old range from 17 to 192 mGy.cm2, and from 30,4 to 136,2 mGy.cm2 for patients with ages from 5 to 10 years old. The differences in the Pka values are due the different dimensions of the radiation field. For the results its possible to conclude that the Pka values are high, in special for patients with ages from 1 to 5 years old, indicating that the collimation of the radiation field is not adequate. (author)

  10. Implications of new correction factors on primary air kerma standards in 60Co-beams

    International Nuclear Information System (INIS)

    Comparisons of primary standards for air kerma in 60Co-beams are re-analysed taking into account the recently developed formalism that defines uniquely the various correction factors and the development of analytic and Monte Carlo methods to quantify these corrections. After a brief historical review of air kerma comparisons and ion chamber calculations, the new corrections are applied in a re-analysis of previously published comparison data. An independent Monte Carlo verification of the analytic point-source non-uniformity correction factor is presented. The combination of new proposed correction factors imply that some national standards should increase by as much as 1% and that the global increase is of the order of 0.6%. (author)

  11. Evaluating air kerma at a medical cyclotron after refined shielding design using the TLD approach

    International Nuclear Information System (INIS)

    Cyclotrons are increasingly constructed at medical universities in Taiwan to produce nuclear medicine. However, their operation generates amounts of highly energetic photons from 18O(p, ?n)18F reactions. This reaction posed a health hazard to the public. Chung Shan University Hospital had to increase its 2-deoxy-2-[18F]-fluoro-D-glucose products in 2011 to 11.5 times that in 2004 and redesign the self-shielded (CTI) Radioisotope Delivery System (RDS)-111 to meet guild requirements regarding the production of positron emission tomography (PET). This study is the first to evaluate air kerma in a CTI RDS-111 cyclotron center with a thermoluminescent dosimeter (TLD). Air kerma of up to 17.0±2.8 mGy/mo indicated that heavy leakage of photons penetrated the PET/CT facility. The new L-shaped concrete shield and added d2 door can adequately protect the public. The minimum detectable limit of air kerma is discussed to demonstrate the reliability of the TLD approach. (author)

  12. Comparison of air-kerma strength determinations for HDR {sup 192}Ir sources

    Energy Technology Data Exchange (ETDEWEB)

    Rasmussen, Brian E.; Davis, Stephen D.; Schmidt, Cal R.; Micka, John A.; DeWerd, Larry A. [Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)

    2011-12-15

    Purpose: To perform a comparison of the interim air-kerma strength standard for high dose rate (HDR) {sup 192}Ir brachytherapy sources maintained by University of Wisconsin Accredited Dosimetry Calibration Laboratory (UWADCL) with measurements of the various source models using modified techniques from the literature. The current interim standard was established by Goetsch et al. in 1991 and has remained unchanged to date. Methods: The improved, laser-aligned seven-distance apparatus of University of Wisconsin Medical Radiation Research Center (UWMRRC) was used to perform air-kerma strength measurements of five different HDR {sup 192}Ir source models. The results of these measurements were compared with those from well chambers traceable to the original standard. Alternative methodologies for interpolating the {sup 192}Ir air-kerma calibration coefficient from the NIST air-kerma standards at {sup 137}Cs and 250 kVp x rays (M250) were investigated and intercompared. As part of the interpolation method comparison, the Monte Carlo code EGSnrc was used to calculate updated values of A{sub wall} for the Exradin A3 chamber used for air-kerma strength measurements. The effects of air attenuation and scatter, room scatter, as well as the solution method were investigated in detail. Results: The average measurements when using the inverse N{sub K} interpolation method for the Classic Nucletron, Nucletron microSelectron, VariSource VS2000, GammaMed Plus, and Flexisource were found to be 0.47%, -0.10%, -1.13%, -0.20%, and 0.89% different than the existing standard, respectively. A further investigation of the differences observed between the sources was performed using MCNP5 Monte Carlo simulations of each source model inside a full model of an HDR 1000 Plus well chamber. Conclusions: Although the differences between the source models were found to be statistically significant, the equally weighted average difference between the seven-distance measurements and the well chambers was 0.01%, confirming that it is not necessary to update the current standard maintained at the UWADCL.

  13. Diaphragm correction factors for free-air chamber standards for air kerma in x-rays

    International Nuclear Information System (INIS)

    At present, only a correction factor for photon transmission, kl, is systematically applied for the entrance diaphragm of free-air chamber standards for air kerma. In the present work, the Monte Carlo code PENELOPE is used to re-evaluate kl for the BIPM standards and new correction factors are calculated for photon scatter and for fluorescence production in the diaphragm. An additional effect arising from electrons emitted from the diaphragm is shown to be significant at the highest photon energies. The results for the radiation qualities used for international comparisons give a combined diaphragm correction factor kdia = 0.9980(3) for the BIPM medium-energy standard at 250 kV. This is significantly different from the factor kl = 0.9996(1) in use at present and it might be concluded that differences are likely to exist for all free-air chamber standards. The effect of using a conical taper at the downstream edge of the diaphragm is shown to be negligible for these radiation qualities.

  14. X-Rays spectrum and air kerma during a mammography study

    International Nuclear Information System (INIS)

    The X-rays spectrum produced in a mammography has been calculated by means of Monte Carlo methods. In this calculation series it is modeled the electrons source, the target and the filter. The spectra were calculated for an energy of the electrons of 28 keV and for targets of W, Mo and Rh. The calculations extended to analyze the effect that produces the filters inclusion in the spectra; the spectra of W-A1, Rh-Rh, Mo-Mo, Mo-Rh and Mo-Be were calculated this way. Using thermoluminescent dosemeters of ZrO2+PTFE the air kerma was measured in five points located on a phantom made with acrylic and water when it is was exposed to a X-rays beam produced by electrons of 24 keV and 10 m A of current that it produces a mammography. The values of the air kerma on the entrance surface of the phantom were compared with the calculated values by means of Monte Carlo methods. The calculated spectra present a continuous component and another discreet and its form is similar to the reported spectra in the literature. The filters inclusion allows the elimination of the low energy photons that do not have utility in the obtaining of the mammography image and only they contribute to deposit a dose in the mamma. The values of the measured air kerma indicate that the five points receive the same air kerma approximately, what means that the beam is homogeneous, of the Monte Carlo calculations we find that the center receives a bigger dose which implies that the beam is not uniform, the explanation on this fact it is attributed to that a simple model was used in the calculations, nevertheless, the average of the air kerma measured on the entrance surface of the phantom was of 0.96 ± 0.03 m G, while the obtained by means of the calculations was of 0.96 ± 0.06 mGy, when comparing both significant differences do not exist. (Author)

  15. Calculated neutron air kerma strength conversion factors for a generically encapsulated Cf-252 brachytherapy source

    CERN Document Server

    Rivard, M J; D'Errico, F; Tsai, J S; Ulin, K; Engler, M J

    2002-01-01

    The sup 2 sup 5 sup 2 Cf neutron air kerma strength conversion factor (S sub K sub N /m sub C sub f) is a parameter needed to convert the radionuclide mass (mu g) provided by Oak Ridge National Laboratory into neutron air kerma strength required by modern clinical brachytherapy dosimetry formalisms indicated by Task Group No. 43 of the American Association of Physicists in Medicine (AAPM). The impact of currently used or proposed encapsulating materials for sup 2 sup 5 sup 2 Cf brachytherapy sources (Pt/Ir-10%, 316L stainless steel, nitinol, and Zircaloy-2) on S sub K sub N /m sub C sub f was calculated and results were fit to linear equations. Only for substantial encapsulation thicknesses, did S sub K sub N /m sub C sub f decrease, while the impact of source encapsulation composition is increasingly negligible as Z increases. These findings are explained on the basis of the non-relativistic kinematics governing the majority of sup 2 sup 5 sup 2 Cf neutron interactions. Neutron kerma and energy spectra resul...

  16. Effects of aluminum-copper alloy filtration on photon spectra, air kerma rate and image contrast

    Scientific Electronic Library Online (English)

    Andréa, Gonçalves; João Manuel Domingos de Almeida, Rollo; Marcelo, Gonçalves; Francisco, Haiter Neto; Frab Norberto, Bóscolo.

    2004-12-01

    Full Text Available Este estudo avaliou a redução da taxa de kerma no ar, o espectro de energia dos raios X e alterações na qualidade da imagem radiográfica. Comparações com várias espessuras do filtro de liga de alumínio-cobre em três diferentes porcentagens foram feitas com o filtro de alumínio. Os experimentos foram [...] feitos utilizando-se um aparelho de raios X odontológico convencional, obtendo radiografias com auxílio de um fantoma de segmento de mandíbula e de uma escala de densidade confeccionada com alumínio laminado. Dependendo da espessura da filtração da liga de alumínio-cobre, o feixe de raios X pôde ser endurecido em relação ao filtro de alumínio. O uso do filtro de liga de alumínio-cobre resultou em 8,40% a 47,33% de redução da taxa média de kerma no ar e indicou contraste da imagem radiográfica sem alteração, quando comparado com a filtração de alumínio, mostrando que os filtros de liga de alumínio-cobre tornam-se alternativas aceitáveis em relação aos filtros de alumínio. Abstract in english This study evaluated the performance of aluminum-copper alloy filtration, without the original aluminum filter, for dental radiography in terms of x-ray energy spectrum, air kerma rate and image quality. Comparisons of various thicknesses of aluminum-copper alloy in three different percentages were [...] made with aluminum filtration. Tests were conducted on an intra-oral dental x-ray machine and were made on mandible phantom and on step-wedge. Depending on the thickness of aluminum-copper alloy filtration, the beam could be hardened and filtrated. The use of the aluminum-copper alloy filter resulted in reductions in air kerma rate from 8.40% to 47.33%, and indicated the same image contrast when compared to aluminum filtration. Aluminum-copper alloy filtration may be considered a good alternative to aluminum filtration.

  17. Air-over-ground calculations of the neutron, prompt, and secondary-gamma free-in-air tissue kerma from the Hiroshima and Nagasaki devices

    International Nuclear Information System (INIS)

    This paper reports preliminary results of the two-dimensional discrete-ordinate, calculations for the air-over-ground transport of radiation from the Hiroshima and Nagasaki weapon devices. It was found that the gamma-ray kerma dominated the total kerma for both environments

  18. Air-kerma strength determination of a miniature x-ray source for brachytherapy applications

    Science.gov (United States)

    Davis, Stephen D.

    A miniature x-ray source has been developed by Xoft Inc. for high dose-rate brachytherapy treatments. The source is contained in a 5.4 mm diameter water-cooling catheter. The source voltage can be adjusted from 40 kV to 50 kV and the beam current is adjustable up to 300 muA. Electrons are accelerated toward a tungsten-coated anode to produce a lightly-filtered bremsstrahlung photon spectrum. The sources were initially used for early-stage breast cancer treatment using a balloon applicator. More recently, Xoft Inc. has developed vaginal and surface applicators. The miniature x-ray sources have been characterized using a modification of the American Association of Physicists in Medicine Task Group No. 43 formalism normally used for radioactive brachytherapy sources. Primary measurements of air kerma were performed using free-air ionization chambers at the University of Wisconsin (UW) and the National Institute of Standards and Technology (NIST). The measurements at UW were used to calibrate a well-type ionization chamber for clinical verification of source strength. Accurate knowledge of the emitted photon spectrum was necessary to calculate the corrections required to determine air-kerma strength, defined in vacuo. Theoretical predictions of the photon spectrum were calculated using three separate Monte Carlo codes: MCNP5, EGSnrc, and PENELOPE. Each code used different implementations of the underlying radiological physics. Benchmark studies were performed to investigate these differences in detail. The most important variation among the codes was found to be the calculation of fluorescence photon production following electron-induced vacancies in the L shell of tungsten atoms. The low-energy tungsten L-shell fluorescence photons have little clinical significance at the treatment distance, but could have a large impact on air-kerma measurements. Calculated photon spectra were compared to spectra measured with high-purity germanium spectroscopy systems at both UW and NIST. The effects of escaped germanium fluorescence photons and Compton-scattered photons were taken into account for the UW measurements. The photon spectrum calculated using the PENELOPE Monte Carlo code had the best agreement with the spectrum measured at NIST. Corrections were applied to the free-air chamber measurements to arrive at an air-kerma strength determination for the miniature x-ray sources.

  19. In situ gamma-ray spectrometry in forests: determination of kerma rate in air from 137Cs

    International Nuclear Information System (INIS)

    A method is presented to determine the kerma rate in air from 137Cs due to Chernobyl fallout in forests. In situ gamma-ray spectra from several forest sites in Russia, in the Ukraine and in Southern Germany are evaluated with the aim of deducing the ratio of primary and forward scattered photons for 137Cs. With this ratio and the results of Monte-Carlo simulations of photon transport the contribution of scattered photons to the total kerma is assessed successfully. Scattered photons contribute between 42% and 50% to the total kerma rate from radiocesium, which is less than according values for grassland areas. The contribution of radiocesium to the total kerma rate varies between 40% and 90%, whereas radiocesium stored in the forest biomass contributes only a few percent. The mean mass depth of radiocesium ranges from 2.6 to 6.4 g cm-2 in the forest soils

  20. Sensitivity/uncertainty analysis for free-in-air tissue kerma due to initial radiation at Hiroshima and Nagasaki

    International Nuclear Information System (INIS)

    Uncertainty estimates and cross correlations by range/survivor have been calculated for the Hiroshima and Nagasaki free-in-air (FIA) tissue kerma obtained from two-dimensional air/ground transport calculations. The uncertainties due to modeling parameter and basic nuclear transport data uncertainties were calculated for 700-, 1000-, and 1500-m ground ranges. Only the FIA tissue kerma due to initial radiation was treated in the analysis; the uncertainties associated with terrain and building shielding and phantom attenuation were not considered in this study. Uncertainties of --20% were obtained for the prompt neutron and secondary gamma kerma and 30% for the prompt gamma kerma at both cities. The uncertainties on the total prompt kerma at Hiroshima and Nagasaki are --18 and 15%, respectively. The estimated uncertainties vary only slightly by ground range and are fairly highly correlated. The total prompt kerma uncertainties are dominated by the secondary gamma uncertainties, which in turn are dominated by the modeling parameter uncertainties, particularly those associated with the weapon yield and radiation sources

  1. Product kerma in the air-area and radiation dose in dental radiodiagnosis

    International Nuclear Information System (INIS)

    The main purpose of patient dosimetry in diagnostic radiology is to determine dosimetric quantities for the establishment and use of reference levels and comparative risk assessment. In recent publications the use of the air kerma-area product, PKA, has been suggested in dental radiology, as this quantity is more closely related to risk. The aim of this study was to perform a preliminary survey of PKA and effective dose in different types of dental examinations. The future perspective is a large-scale survey for the establishment and use of diagnostic reference levels in dentistry in Brazil. (author)

  2. Preliminary study on quality audit for air kerma strength determination of high dose rate brachytherapy sources

    International Nuclear Information System (INIS)

    Brachytherapy is one of the modes of treatment of cancerous cells. High dose rate (HDR) brachytherapy using high activity 192Ir source has become very popular for all brachytherapy applications worldwide. The accurate dose delivery to the patient depends on many dosimetric parameters. Air Kerma Strength is one of the clinical parameters which is recommended by many international bodies to specify the brachytherapy source strength and used in the TG-43 dosimetry formalism. Our study concludes that TLD based Quality Audit method can be used for postal audit of HDR brachytherapy sources strength verification

  3. Proposed specification for a primary standard of air kerma for 60Co, 137Cs and 192Ir ?-ray sources

    International Nuclear Information System (INIS)

    The three cavity chambers, the mean response of which constitutes the primary standard of air kerma for 60Co and 137Cs ?-rays in the United Kingdom, have been in continuous, almost daily, use at the National Physical Laboratory (NPL) since 1956. These chambers were initially designed for use with 2 MV X-rays at therapy level air kerma rates. However since 1978 they have also been used for protection level air kerma rates, initially, with X-rays generated at 1 MV and 2 MV and more recently with 60Co and 137Cs ?-rays. They have been used for therapy level air kerma calibrations with 60Co ?-rays since 1997 following the demise of the NPL 2 MV Van de Graaff generator. This report describes the proposals for a new primary standard and the methods that will be used to give a better performance than the present standard when used with air kerma rates from as high as 1 Gy min-1 down to 10 mGy hr-1. The design will also seek to ensure that the standard will be capable of providing traceable calibration for 192Ir high dose rate brachytherapy sources. (author)

  4. Air kerma and absorbed dose on the torso of a patient during a mammography study;Kerma en aire y dosis absorbida en el torso de una paciente durante un estudio mastografico

    Energy Technology Data Exchange (ETDEWEB)

    Hernadez O, M.; Duran M, H. A.; Pinedo S, A.; Gonzalez G, R.; Guerra M, J. A.; Salas L, M. A.; Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Calle Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico); Rivera M, T. [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Av. Legaria 694, 11500 Mexico D. F. (Mexico); Azorin N, J., E-mail: mar_h2o@hotmail.co [Universidad Autonoma Metropolitana, Unidad Iztapalapa, Av. San Rafael Atlixco 186, 09340 Mexico D. F. (Mexico)

    2009-10-15

    Two dosimetric magnitudes, due to the dispersed radiation, have been determined during a mammography study. The magnitudes that were determined are the kerma at the entrance of the torso and the absorbed dose by the torso. This determination was made in a paraffin phantom and with thermoluminescent dosemeters. One of the important parameters in the radiological protection of a patient to which is practiced a mammography is the value of the media glandular dose. However, during the taking of the X-ray a radiation portion that impacts on the mammary gland it is dispersed toward the patient's torso. In this work thermoluminescent dosemeters of ZrO{sub 2} has been used to determine the kerma at the entrance of the torso like the absorbed dose. The dosemeters was placed on the surface of the torso phantom while to the mamma phantom was made the mammography. As mamma phantom was used glucose serum to 5%. Of the obtained results we find that 3% of the air kerma at the entrance of the mamma it corresponds at the air kerma that receives the torso and 3.2% of the media glandular dose it is the absorbed dose of the same one. Another important result is the percentage value of the air kerma on the entrance of the thyroid area during a mammography, due to the dispersed radiation, it is 4% of the kerma at the entrance of the mamma. The air kerma at the entrance of the thyroid is of 0.41 +-0.07 mGy, 10% of this value corresponds to the absorbed dose by the thyroid. Therefore, it is observed that the media glandular dose and the air kerma at the entrance of the mamma they influence on the dispersed radiation toward the torso. Also, the superior part of the torso has less attenuation capacity to the dispersed radiation that those located in the inferior part. Therefore, the thyroid receives the major quantity of air kerma at the entrance. (Author)

  5. Product kerma in the air-area and radiation dose in dental radiodiagnosis; Produto kerma ar-area e dose efetiva em radiodiagnostico odontologico

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Alessandro Martins da, E-mail: amcosta@usp.br [Universidade de Sao Paulo (USP), Ribeirao Preto, SP (Brazil). Faculdade de Filosofia, Ciencias e Letras. Dept. de Fisica

    2014-07-01

    The main purpose of patient dosimetry in diagnostic radiology is to determine dosimetric quantities for the establishment and use of reference levels and comparative risk assessment. In recent publications the use of the air kerma-area product, PKA, has been suggested in dental radiology, as this quantity is more closely related to risk. The aim of this study was to perform a preliminary survey of PKA and effective dose in different types of dental examinations. The future perspective is a large-scale survey for the establishment and use of diagnostic reference levels in dentistry in Brazil. (author)

  6. Kerma rate evaluation in the air in a room interventional cardiology

    International Nuclear Information System (INIS)

    In recent years, the number of interventional cardiology procedures is increasing. However, due to the long time of fluoroscopy in these procedures, care teams can receive high doses of radiation. The radiation scattered by the patient is not uniform, and their assessment is of utmost importance. This study aimed to estimate and map the kerma rate in the air at the time of the gonads, in an interventional cardiology room, seeking to optimize the dose absorbed by individuals occupationally exposed to ionizing radiation. For data collection, the room was divided into quadrants of 1m2, totaling 40 collection points. The simulator was positioned so that its entry surface was located in the interventional reference point. Were chosen the conditions that simulate angiography and angioplasty procedures performed in the service. The data were obtained for height of 1 meter, gonad region. The results obtained for kerma rates in air, in quadrants, show that higher measured values was in the vicinity of the X-ray tube. Has been found that the medical staff are more exposed, because of its location during the procedure, around the table. The law of the inverse square distance of the farthest points of the X-ray tube were verified

  7. Avaliação do kerma no ar na superfície de entrada e da qualidade da imagem em radiografias de tórax / Evaluation of entrance surface air kerma rate and clinical images quality in chest radiography

    Scientific Electronic Library Online (English)

    Angelo Bernardo Brasil de, Souza; Simone Kodlulovich, Dias; Fernando Mecca, Augusto; Winston Andrade, Marques.

    2009-10-01

    Full Text Available OBJETIVO: Avaliar os fatores de técnica utilizados durante exames de tórax póstero-anterior em pacientes-padrão e correlacioná-los aos valores de kerma no ar na superfície de entrada e à qualidade das imagens clínicas. MATERIAIS E MÉTODOS: O estudo foi realizado em três hospitais do Rio de Janeiro, [...] num total de cinco salas de raios X, com dez pacientes por sala. As imagens foram avaliadas pelos radiologistas dos serviços segundo o protocolo europeu. O kerma no ar na superfície de entrada foi estimado a partir da curva de rendimento do equipamento de raios X, que foi obtida utilizando câmara de ionização acoplada a um eletrômetro. Análise de variância foi realizada para verificar se a diferença entre os valores de kerma no ar na superfície de entrada é significativa. RESULTADOS: Os valores de kerma no ar na superfície de entrada variaram entre 0,05 e 0,26 mGy, com média 60% inferior ao nível de referência publicado na Portaria 453. Das imagens avaliadas, 98% atenderam acima de 65% dos critérios de qualidade. CONCLUSÃO: Para um padrão de qualidade da imagem, aceitável para o diagnóstico, verificou-se ampla variação do kerma no ar na superfície de entrada para pacientes-padrão. Isto demonstra a falta de padronização dos fatores de técnica e a existência de um potencial de redução do valor do kerma no ar na superfície de entrada. Abstract in english OBJECTIVE: To evaluate technical factors involved in posteroanterior chest radiography in standard patients, and correlating them with entrance surface air kerma rate and with the clinical images quality. MATERIALS AND METHODS: The present study was developed at three hospitals in Rio de Janeiro, Br [...] azil, involving a total of five x-ray rooms, with ten patients per room. The images were evaluated by the radiologists of the institutions, in accordance with the European protocol. The estimation of surface entrance air kerma rate was based on the x-ray equipment output curve obtained with an ionization chamber coupled with an electrometer. Variance analysis was performed to evaluate the significance of the difference between entrance surface air kerma rates. RESULTS: Entrance surface air kerma rates ranged between 0.05 and 0.26 mGy, with a mean value 60% lower than the reference level established by the Order (Portaria) 453. Among the images evaluated, 98% fulfilled > 65% of the images quality criteria. CONCLUSION: For a standard image quality that is acceptable for diagnosis purposes, a significant variation was observed in the entrance surface air kerma rate for standard patients, demonstrating the lack of technical factors standardization and a potential for decreasing the entrance surface air kerma rate.

  8. Relationship between absorbed dose-rate in water and reference air kerma-rate for I-125 seeds

    International Nuclear Information System (INIS)

    To clinically utilize measured relative three-dimensional dose distribution about I-125 seeds in water, the absolute dose-rate in medium per source strength specification unit must be known at one point. Source strength is defined as air kerma-rate in free space along the transverse bisector of the source at a reference distance. The author has used the Monte Carlo method to calculate the dose-rate in water 1 cm from the source along its perpendicular bisector per unit reference air-kerma rate for model 6711, 6701, and 6702 seeds. The results indicate that published dose-rate constants overestimate this quantity by 10%-17%

  9. Kerma rate evaluation in the air in a room interventional cardiology; Avaliacao da taxa de Kerma no ar em uma sala de cardiologia intervencionista

    Energy Technology Data Exchange (ETDEWEB)

    Real, Jessica V.; Luz, Renata M. da, E-mail: jessica.real@pucrs.br, E-mail: renata.luz@pucrs.br [Hospital Sao Lucas (HSL/PUCRS), Porto Alegre, RS (Brazil); Fröhlich, Bruna D.; Silva, Ana Maria Marques da, E-mail: bruna.frohlich@acad.pucrs.br, E-mail: ana.marques@pucrs.br [Pontificia Universidade Catolica do Rio Grande do Sul (PUCRS), Porto Alegre, RS (Brazil)

    2014-07-01

    In recent years, the number of interventional cardiology procedures is increasing. However, due to the long time of fluoroscopy in these procedures, care teams can receive high doses of radiation. The radiation scattered by the patient is not uniform, and their assessment is of utmost importance. This study aimed to estimate and map the kerma rate in the air at the time of the gonads, in an interventional cardiology room, seeking to optimize the dose absorbed by individuals occupationally exposed to ionizing radiation. For data collection, the room was divided into quadrants of 1m{sup 2}, totaling 40 collection points. The simulator was positioned so that its entry surface was located in the interventional reference point. Were chosen the conditions that simulate angiography and angioplasty procedures performed in the service. The data were obtained for height of 1 meter, gonad region. The results obtained for kerma rates in air, in quadrants, show that higher measured values was in the vicinity of the X-ray tube. Has been found that the medical staff are more exposed, because of its location during the procedure, around the table. The law of the inverse square distance of the farthest points of the X-ray tube were verified.

  10. Effect of the diaphragm of free-air ionisation chamber for X-ray air-kerma measurements

    International Nuclear Information System (INIS)

    Free-air ionisation chambers are widely used at standards laboratories as primary standards for absolute measurements of air kerma in X-ray fields. The area of the diaphragm aperture of a free-air ionisation chambers is an important factor for absolute measurements because it defines the size of the X-ray beam incident on the free-air chamber. In this study, correction factors for the contribution of X rays transmitted through the diaphragm of a free-air ionisation chamber and those scattered from the surface of the diaphragm aperture are obtained by Monte Carlo simulation for two different sized free-air ionisation chambers and for various diaphragm aperture sizes, X-ray energies and source-to-chamber distances. (authors)

  11. New primary ionization chambers at LNE-LNHB for determining the air kerma in a cobalt-60 beam

    International Nuclear Information System (INIS)

    For radioprotection, the reference quantity is air kerma. For an cobalt-60 beam, the reference dosimeter is a cavity ionization chamber whose volume is measured. The new LNE-LNHB reference is based on six different chambers instead of one as was done previously. Although every new ionization chamber was treated as much as possible in the same way (manufacturing, measurements of volumes, wall effect calculations, current corrections), a maximum discrepancy of 0.2% was observed between the final measurement results from each chamber. The final value of the air kerma rate in reference conditions was determined as the mean value of the measurement results from all six chambers. Among the different factors whose determination is necessary to calculate the air kerma rate, some are considered independent of or common to all the graphite-walled ionization chambers (for example, mean energy expended by an electron to produce an ion pair in dry air), while others vary for each chamber (for example, air cavity ionic collection volume). Considering that the uncertainties of the individual ionization chamber measurement results seem slightly underestimated, the uncertainty on the mean of the six chamber-dependent factors products was taken equal to the standard deviation of the sample composed of the six chamber-dependent factors products (0.08%). Compared to the previous standard, the air kerma rate of the 60Co photon beam would then increase by 0.09% and the air kerma rate uncertainty would drop from 0.38% to 0.31%. This article describes the procedure used to establish the primary standard in terms of absorbed dose to tissue of LNE-LNHB. (authors)

  12. Sampling size in the verification of manufactured-supplied air kerma strengths

    International Nuclear Information System (INIS)

    Quality control mandate that the air kerma strengths (SK) of permanent seeds be verified, this is usually done by statistics inferred from 10% of the seeds. The goal of this paper is to proposed a new sampling method in which the number of seeds to be measured will be set beforehand according to an a priori statistical level of uncertainty. The results are based on the assumption that the SK has a normal distribution. To demonstrate this, the SK of each of the seeds measured was corrected to ensure that the average SK of its sample remained the same. In this process 2030 results were collected and analyzed using a normal plot. In our opinion, the number of seeds sampled should be determined beforehand according to an a priori level of statistical uncertainty

  13. The ratios of effective dose to entrance skin dose to the air kerma for some medical sources

    Energy Technology Data Exchange (ETDEWEB)

    Wise, K.N. [Australian Radiation Laboratory, Yallambie, VIC (Australia)

    1998-03-01

    Results are presented for the ratios of the effective dose to skin entrance dose and to air kerma for broad beams of radiation expected to be encountered by medical workers. These workers are monitored by the Personal Radiation Monitoring Service (PRMS) using thermoluminescent dosimeters worn at the front of the body to provide estimates of the entrance skin dose. Factors are given for converting estimates of entrance skin dose to effective dose as defined by the International Commission on Radiological Protection (ICRP 1991) for beams incident on the body by one of three modes-from the front of the subject, from the back of the subject or by rotation around the subject. Additional tables are also given to calculate effective dose for these beams from a measurement of air kerma free-in-air 4 figs., 9 tabs.

  14. Age-Dependent Dose in Organs per Unit Air Kerma Free-in-Air: Conversion Coefficients for Environmental Exposure

    International Nuclear Information System (INIS)

    Conversion coefficients from air kerma free-in-air to effective dose and dose in organs have been calculated for hermaphrodite 1, 5, 10, 15 year old children and adult anthropomorphic mathematical models. The 15 year old child phantom is also used as the adult female phantom. The irradiation geometry considered was the phantom standing on an almost infinite plane source, which is the geometry normally used for detector's calibration for environmental in situ measurements. The ADAM computer code has been modified to use the phantoms described by Cristy for the children phantoms, the adult male phantom is described in the ICRP Report 23. Thirty-six incident energies ranging from 10 keV to 10 MeV were selected for the incident radiation. (author)

  15. Study and determination of the national dosimetric standards in terms of air kerma for X-rays radiation fields of low and medium-energies

    International Nuclear Information System (INIS)

    Progress in radiation protection and radiotherapy, and the increased needs in terms of accuracy lead national metrology institutes to improve the standard. For ionizing radiation, the standard is defined by an absolute instrument used for air kerma rate measurement. The aim of the thesis is to establish standards, in terms of air kerma for X-rays beams of low and medium-energies. This work enables to complement the standard beam range of the Laboratoire National Henri Becquerel (LNHB). Two free-air chambers have been developed, WK06 for medium-energy and WK07 for low-energy. The air-kerma rate is corrected by several correction factors. Some are determined experimentally; and the others by using Monte Carlo simulations. The uncertainty budget of the air-kerma rate at one standard deviation has been established. These dosimetric standards were compared with those of counterparts' laboratories and are consistent in terms of degree of equivalence. (author)

  16. Linearity of the air kerma values in relation to exposure times in a dental X radiation system

    International Nuclear Information System (INIS)

    The objective of this study was the evaluation of a dental X radiation system intensity variation studying the linearity of the air kerma rate in relation to the exposure time. This study was performed in a Dabi Atlante dental X radiation system. For the exposure time measurements the cone spacer was positioned perpendicular to the detector and the time was varied from 0 to 1.5 s. The air kerma measurements were made in the same conditions for FDD=20.0 cm and 27.5 cm. After that, the obtained values were plotted and a linear adjust was done for each set of measurements. The results showed that the maximum variation obtained was 7% for the third group of measurements for the exposure time of 1.5 s. This variation is less than the recommended limit of 20% published by the Brazilian Health Ministry Regulation 453. (author)

  17. Comparison of the standards for air kerma of the VNIIM and the BIPM for 60Co gamma radiation

    International Nuclear Information System (INIS)

    An indirect comparison of the standards for air kerma of the D.I. Mendeleev Institute for Metrology (VNIIM), Russian Federation, and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 60Co radiation beam of the BIPM in November 2009. The comparison result, based on the calibration coefficient for a transfer standard and expressed as a ratio of the VNIIM and the BIPM standards for air kerma, is 1.0008 with a combined standard uncertainty of 1.8 * 10-3. The degrees of equivalence between the VNIIM and the other participants in this BIPM.RI(I)-K1 key comparison have been calculated and the results are presented in the form of a matrix. A graphical presentation is also given. (authors)

  18. Comparison of air kerma standards for medium-energy X-radiation between the MKEH and the IAEA

    International Nuclear Information System (INIS)

    A comparison of the air kerma standards for medium-energy x-radiation was performed between the MKEH and the IAEA. Two reference class ionization chambers of the IAEA, traceable to the PTB with volumes 1000 cm3 and 100 cm3, and the ISO 4037 N-40, N-60, N-120 and N-300 standard beam qualities were selected for the comparison. The calibration coefficients, NK, were determined for both chambers at the MKEH in August 2011 and before and after this at the IAEA Dosimetry Laboratory. The comparison ratio of the calibration coefficients normalized to the previous comparison results of the PTB and MKEH primary air kerma standards was in the range from 0.989 to 0.994 for the beam qualities used. The relative expanded (k = 2) uncertainty for each of these ratios is around 2%. (authors)

  19. Product estimate of air kerma-area and the air kerma in the input surface of the skin of pediatric patients undergoing chest X-ray; Estimativa do produto kerma ar-area e do kerma ar na superficie de entrada da pele de pacientes pediatricos submetidos a radiografia de torax

    Energy Technology Data Exchange (ETDEWEB)

    Villa-Chan, Beatriz; Carvalho, Aline; Andrade, Marcos Ely A.; Barros, Vinicius S.M. de; Khoury, Helen J., E-mail: beatrizvillachan@gmail.com, E-mail: alinecx90@gmail.com, E-mail: marcos.ely@gmail.com, E-mail: vsmdbarros@gmail.com, E-mail: hjkhoury@gmail.com [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Energia Nuclear

    2014-07-01

    The aim of this paper is to evaluate the entrance air kerma (Ka,e) and the product air kerma-area (Pka) for chest examinations performed with pediatric patients in a large public hospital of Recife. For this study 89 examinations of patient with ages from zero to 10 years old were evaluated. The results showed that the mean Ka,e values, for patients of 0-1 years old, 1-5 years old and 5-10 years old, were, respectively, 100 mGy, 120 mGy and 100 mGy. The Pka values for newborn patients range from 11,9 to 58,4 mGy.cm{sup 2}, for patients with 1 to 5 years old range from 17 to 192 mGy.cm{sup 2}, and from 30,4 to 136,2 mGy.cm{sup 2} for patients with ages from 5 to 10 years old. The differences in the Pka values are due the different dimensions of the radiation field. For the results its possible to conclude that the Pka values are high, in special for patients with ages from 1 to 5 years old, indicating that the collimation of the radiation field is not adequate. (author)

  20. Comparison of the standards of air kerma of the ENEA-INMRI and the BIPM for 60Co ? rays

    International Nuclear Information System (INIS)

    A new comparison of the standards for air kerma of the Istituto Nazionale di Metrologia delle Radiazioni Ionizzanti of the Ente per le Nuove Tecnologie, l'Energia e l'Ambiente, Italy (ENEA-INMRI) and of the Bureau International des Poids et Mesures (BIPM) has been carried out in 60Co radiation. The comparison result, expressed as a ratio of the ENEA and BIPM standards, is 1.0051 (0.0026). (authors)

  1. Comparison of the standards of air kerma of the LNMRI/IRD and the BIPM for 60Co ? rays

    International Nuclear Information System (INIS)

    A third comparison of the standards for air kerma of Laboratorio Nacional de Metrologia das Radiacoes Ionizantes/Institute de Radioprotecao e Dosimetria (LNMRI/IRD), Rio de Janeiro, Brazil and of the Bureau International des Poids et Mesures (BIPM) has been carried out in 60Co radiation. The comparison result is 1.0007 and demonstrates that the LNMRI/IRD and BIPM standards agree closely, as was the case for the previous comparisons in 1986 and 1996. (authors)

  2. Air kerma standardization for diagnostic radiology, and requirements proposal for calibration laboratories

    International Nuclear Information System (INIS)

    The demand for calibration services and quality control in diagnostic radiology has grown in the country since the publication of the governmental regulation 453, issued by the Ministry of Health in 1998. At that time, to produce results facing the new legislation, many laboratories used different standards and radiation qualities, some of which could be inadequate. The international standards neither supplied consistent radiation qualities and standardization for the different types of equipment available. This situation changed with the publication of the new edition of the IEC 61267 standard, published in 2005. A metrology network was created, but it is not yet accredited by the accreditation organism of the country, INMETRO. The objective of this work was to implement the standardization of the air kerma for the un attenuated qualities (RQR) of IEC 61267, and to develop a requirement proposal for instruments calibration laboratories. Results of interlaboratory comparisons demonstrate that the quantity is standardized and internationally traceable. A laboratory requirement proposal was finalized and it shall be submitted to INMETRO to be used as auxiliary normative document in laboratory accreditation. (author)

  3. Verification of air-kerma strength of 125I seed for permanent prostate implants in Japan

    International Nuclear Information System (INIS)

    To assure the physical quality of brachytherapy, we investigated the difference between measured and manufacturer's stated source strengths in a single model SourceTech Medical (STM) 1251 125I seed. A well-type ionization chamber with a single-seed holder was used to measure the source strength of 2412 125I seeds before implant in 34 patients. The air-kerma strength was 0.450 U for all cases. The mean source strength for each patient was measured and compared with the manufacturer's stated value. The deviation from the measured value was compared with the tolerance range of the American Association of Physicists in Medicine (AAPM) TG-56 report's recommendation. The measured source strength was higher than the manufacturer's stated value, with a median difference of 1% (range, -2% to 5%). Sixteen of the totals of 2412 seeds (0.7%) were more than 5% different from the manufacturer's stated value. The median standard deviation (SD) from the mean value was 2.2% (range, 1.1% to 2.5%) for all patients. This is the first report of a single-seed assay performed for the model STM1251 125I seed. In this study the manufacturer's stated strength agreed well with the measured value. Nevertheless, the advisability of performing a single-seed assay at every institution should be considered, by referring to the appropriate regulations; for example, those used in the United States. (author)

  4. Calculation of conversion factor of Kerma in the air for ambient dose equivalent in radiotherapy

    International Nuclear Information System (INIS)

    This work aims to estimate the average conversion factor of Kerma in air to H * (10) using photon beams coming from clinic linear accelerators, transmitted through concrete walls of a radiotherapic treatment room. The transmitted photon spectra by both 1 meter and 2 meters concrete walls, in an area of 40 x 40 cm2, were calculated when the primary beam impart in an angle of 0 deg. The (secondary) photon beams transmitted respectively by 0,5 meter, 1,0 meter, 1,0 meter and 2,0 meter concrete walls, after they scattered by an angle of 90 deg in a cylindric phantom inside the room, were also determined. Generally, 50 millions of histories were computed for each simulation made for the primary beam. For the 90 deg spread, the number of histories was 100 millions. The computational code used on this work was the MCNP4B. The most common clinic accelerators used on radiotheraphic treatments were used on this work CLINAC-4, CLINAC-6, CLINAC-18 and CLINAC-2500. From the spectra analysis obtained in this work, it was possible to dispose the conversion factor for realistic beams found in radiotherapeutic establishment. (author)

  5. Exposure and air-kerma standards for cobalt-60 gamma rays

    International Nuclear Information System (INIS)

    The implementation of the measuring conditions for the determination of the quantities exposure and air-kerma for Cobalt-60 gamma rays have been done at the Laboratorio Nacional de Metrologia das Radiacoes Ionizantes (LNMRI). Several years of work have already been done, and the results so far indicate that both quantities can be measured accordingly with the recommendations of the International Organizations and with uncertainties comparable with the ones practiced in similar laboratories. The comparisons done with the data obtained at the Bureau International des Poids et Mesures with their standards and experimental conditions have shown an excellent agreement, which strongly indicates that the LNMRI standards have an appropriate design and characteristics to be standards of high quality and performance. The efforts made during the last years to accomplish this aim, have been successful. Hence, the LNMRI is now in position to measure those quantities and to proceed with the periodical international intercomparisons in order to maintain the traceability to the International Metrology Network. (author)

  6. Entrance surface air kerma in x-ray systems for paediatric interventional cardiology: a national survey

    International Nuclear Information System (INIS)

    The aims of this work were to report the results of a national survey on entrance surface air kerma (ESAK) values for different phantom thicknesses and operation modes in paediatric interventional cardiology (IC) systems and to compare them with previous values. The national survey also offers suggested investigation levels (ILs) for ESAK in paediatric cardiac procedures. ESAK was measured on phantoms of 4-16 cm thickness of polymethyl methacrylate slabs. For low fluoroscopy mode (FM), ESAK rates ranged from 0.11 to 33.1 mGy min-1 and for high FM from 0.34 to 61.0 mGy min-1. For cine mode, values of ESAK per frame were from 1.9 to 78.2 μGy fr-1. The ILs were suggested as the third quartile of the values measured. This research showed lower ESAK values than in previous research, particularly for ESAK values in cine modes. This work represents a first step towards launching a national programme in paediatric dosimetry for IC procedures. (authors)

  7. NaI(Tl) scintillator detectors stripping procedure for air kerma measurements of diagnostic X-ray beams

    International Nuclear Information System (INIS)

    Air kerma is an essential quantity for the calibration of national standards used in diagnostic radiology and the measurement of operating parameters used in radiation protection. Its measurement within the appropriate limits of accuracy, uncertainty and reproducibility is important for the characterization and control of the radiation field for the dosimetry of the patients submitted to diagnostic radiology and, also, for the assessment of the system which produces radiological images. Only the incident beam must be considered for the calculation of the air kerma. Therefore, for energy spectrum, counts apart the total energy deposition in the detector must be subtracted. It is necessary to establish a procedure to sort out the different contributions to the original spectrum and remove the counts representing scattered photons in the detector’s materials, partial energy deposition due to the interactions in the detector active volume and, also, the escape peaks contributions. The main goal of this work is to present spectrum stripping procedure, using the MCNP Monte Carlo computer code, for NaI(Tl) scintillation detectors to calculate the air kerma due to an X-ray beam usually used in medical radiology. The comparison between the spectrum before stripping procedure against the reference value showed a discrepancy of more than 63%, while the comparison with the same spectrum after the stripping procedure showed a discrepancy of less than 0.2%

  8. Direct calibration of a reference standard against the air kerma strength primary standard, at 192Ir HDR energy

    International Nuclear Information System (INIS)

    The primary standard of low air kerma rate sources or beams, maintained at the Radiological Standards Laboratory (RSL) of the Bhabha Atomic Research Centre (BARC), is a 60 cm3 spherical graphite ionization chamber. A 192Ir HDR source was standardized at the hospital site in units of air kerma strength (AKS) using this primary standard. A 400 cm3 bakelite chamber, functioning as a reference standard at the RSL for a long period, at low air kerma rates (compared to external beam dose rates), was calibrated against the primary standard. It was seen that the primary standard and the reference standard, both being of low Z, showed roughly the same scatter response and yielded the same calibration factor for the 400 cm3 reference chamber, with or without room scatter. However, any likelihood of change in the reference chamber calibration factor would necessitate the re-transport of the primary standard to the hospital site for re-calibration. Frequent transport of the primary standard can affect the long-term stability of the primary standard, due to its movement or other extraneous causes. The calibration of the reference standard against the primary standard at the RSL, for an industrial type 192Ir source maintained at the laboratory, showed excellent agreement with the hospital calibration, making it possible to check the reference chamber calibration at RSL itself. Further calibration procedures have been developed to offer traceable calibration of the hospital well ionization chambers. (author)

  9. Air kerma standardization for diagnostic radiology, and requirements proposal for calibration laboratories; Padronizacao da grandeza Kerma no ar para radiodiagnostico e proposta de requisitos para laboratorios de calibracao

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, Manoel Mattos Oliveira

    2009-07-01

    The demand for calibration services and quality control in diagnostic radiology has grown in the country since the publication of the governmental regulation 453, issued by the Ministry of Health in 1998. At that time, to produce results facing the new legislation, many laboratories used different standards and radiation qualities, some of which could be inadequate. The international standards neither supplied consistent radiation qualities and standardization for the different types of equipment available. This situation changed with the publication of the new edition of the IEC 61267 standard, published in 2005. A metrology network was created, but it is not yet accredited by the accreditation organism of the country, INMETRO. The objective of this work was to implement the standardization of the air kerma for the un attenuated qualities (RQR) of IEC 61267, and to develop a requirement proposal for instruments calibration laboratories. Results of interlaboratory comparisons demonstrate that the quantity is standardized and internationally traceable. A laboratory requirement proposal was finalized and it shall be submitted to INMETRO to be used as auxiliary normative document in laboratory accreditation. (author)

  10. Conversion of Airborne Gamma ray Spectra to Ground Level Air Kerma Rates

    DEFF Research Database (Denmark)

    Bargholz, Kim; Korsbech, Uffe C C

    1997-01-01

    A new method for relating airborne gamma-ray spectra to dose rates and kerma rates at ground level is presented. Dependent on flying altitude 50 m to 125 m the method gives correct results for gamma energies above 250 keV respective 350 keV. At lower energies the method underestimate the dose or kerma rates; by having a large fraction of the ground level gamma-rays at energies below 350 keV special care should be taken at an interpretation of the results.

  11. Study and determination of the national dosimetric standards in terms of air kerma for X-rays radiation fields of low and medium-energies; Etude et realisation des references dosimetriques nationales en termes de kerma dans l'air pour les faisceaux de rayons X de basses et moyennes energies

    Energy Technology Data Exchange (ETDEWEB)

    Ksouri, W

    2008-12-15

    Progress in radiation protection and radiotherapy, and the increased needs in terms of accuracy lead national metrology institutes to improve the standard. For ionizing radiation, the standard is defined by an absolute instrument used for air kerma rate measurement. The aim of the thesis is to establish standards, in terms of air kerma for X-rays beams of low and medium-energies. This work enables to complement the standard beam range of the Laboratoire National Henri Becquerel (LNHB). Two free-air chambers have been developed, WK06 for medium-energy and WK07 for low-energy. The air-kerma rate is corrected by several correction factors. Some are determined experimentally; and the others by using Monte Carlo simulations. The uncertainty budget of the air-kerma rate at one standard deviation has been established. These dosimetric standards were compared with those of counterparts' laboratories and are consistent in terms of degree of equivalence. (author)

  12. Distribution of kerma rate in the air inside of hemodynamic room for typical projections of interventionist cardiology procedures

    International Nuclear Information System (INIS)

    The evaluation of dose to physicians involved in Interventional Cardiology (IC) is an extreme important matter due to the high and non-uniform distribution of dose values. The radiation control during each procedure is complex and the reasons for the high exposures have many different causes. Many international recommendations have already been written aiming the radiation protection optimization in IC. In Brazil, there is not any special orientation for the protection of those occupational persons, nor a specific legislation. The purpose of this work is to evaluate the air kerma rate at critical anatomic regions of the occupationally exposed staff that carry out IC procedures, in representative incidences in order to give subsidies for individual monitoring procedures implementation and to give more information about their radiation protection. The air kerma rate has been measured in the often used condition in the two more common IC procedures namely angiography and coronary angioplasty, using an adult patient simulator irradiated under RAO, LAO and AP projections for fluoro and digital acquisition modes. The measurements have been made in 45 points around the examination table at 5 different representatives heights of: eyes lens, thorax, hands, gonads and knees. AP projection shows the smaller scattered radiation contributions and a more homogeneous exposure distribution. The digital acquisition mode gives air kerma rates about 4 times higher than fluoro mode for LAO projection in the position occupied by the interventionist doctor, the anesthetist and the nursing staff. The most critical anatomic regions are: knees and gonads (without protection). On the physician hands position, values as high as 5 mGy/h have been measured, which can overpass, depending on the number of procedures done, the individual occupational annual limit. Therefore, in IC it is necessary to implement additional protection tools, elaborate safety guides (based on international experiences and recommendations) and establish a permanent radiation protection training programs. (author)

  13. Comparison of the standards of air kerma of the ENEA-INMRI and the BIPM for 137Cs gamma rays

    International Nuclear Information System (INIS)

    A comparison of the standards of air kerma of the Istituto Nazionale di Metrologia delle Radiazioni Ionizzanti of the Ente per le Nuove Tecnologie, l'Energia e l'Ambiente, Italy (ENEA-INMRI) and of the Bureau International des Poids et Mesures (BIPM) was carried out in 137Cs radiation in 1998. The comparison result, updated for changes in the standards in 2003 and 2009, is 0.9927 (0.0067) and demonstrates that the ENEA-INMRI and BIPM standards are in agreement within the uncertainties. (authors)

  14. Comparison of the standards for air kerma of the ENEA-INMRI and the BIPM for 60Co gamma radiation

    International Nuclear Information System (INIS)

    A comparison of the standards of air kerma of the Istituto Nazionale di Metrologia delle Radiazioni Ionizzanti of the Ente per le Nuove Tecnologie, l'Energia e l'Ambiente, Italy (ENEA-INMRI) and of the Bureau International des Poids et Mesures (BIPM) has been carried out in 60Co radiation. The comparison result, declared in 2002, is 1.0103 (0.0026). The difference between the ENEA-INMRI and BIPM standards is consistent with the various changes that have been introduced since the previous comparisons that were in agreement within the comparison uncertainties. (authors)

  15. Air kerma standard for calibration of well-type chambers in Brazil using 192Ir HDR sources and its traceability

    International Nuclear Information System (INIS)

    In Brazil there are over 100 high dose rate (HDR) brachytherapy facilities using well-type chambers for the determination of the air kerma rate of 192Ir sources. This paper presents the methodology developed and extensively tested by the Laboratorio de Ciencias Radiologicas (LCR) and presently in use to calibrate those types of chambers. The system was initially used to calibrate six well-type chambers of brachytherapy services, and the maximum deviation of only 1.0% was observed between the calibration coefficients obtained and the ones in the calibration certificate provided by the UWADCL. In addition to its traceability to the Brazilian National Standards, the whole system was taken to University of Wisconsin Accredited Dosimetry Calibration Laboratory (UWADCL) for a direct comparison and the same formalism to calculate the air kerma was used. The comparison results between the two laboratories show an agreement of 0.9% for the calibration coefficients. Three Brazilian well-type chambers were calibrated at the UWADCL, and by LCR, in Brazil, using the developed system and a clinical HDR machine. The results of the calibration of three well chambers have shown an agreement better than 1.0%. Uncertainty analyses involving the measurements made both at the UWADCL and LCR laboratories are discussed.

  16. Comparison of the standards for air kerma of the VNIIM and the BIPM for 60Co gamma radiation

    Science.gov (United States)

    Kessler, C.; Allisy-Roberts, P. J.; Oborin, A. V.; Villevalde, A. Y.

    2011-01-01

    An indirect comparison of the standards for air kerma of the D I Mendeleyev Institute for Metrology (VNIIM), Russian Federation, and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 60Co radiation beam of the BIPM in November 2009. The comparison result, based on the calibration coefficient for a transfer standard and expressed as a ratio of the VNIIM and the BIPM standards for air kerma, is 1.0008 with a combined standard uncertainty of 1.8 × 10-3. The degrees of equivalence between the VNIIM and the other participants in this BIPM.RI(I)-K1 key comparison have been calculated and the results are presented in the form of a matrix. A graphical presentation is also given. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI Section I, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  17. Comparison of air kerma standards for medium-energy x-radiation between the MKEH and the IAEA

    Science.gov (United States)

    Csete, István; Czap, Ladislav; Gomola, Igor

    2012-01-01

    A comparison of the air kerma standards for medium-energy x-radiation was performed between the MKEH and the IAEA. Two reference class ionization chambers of the IAEA, traceable to the PTB with volumes 1000 cm3 and 100 cm3, and the ISO 4037 N-40, N-60, N-120 and N-300 standard beam qualities were selected for the comparison. The calibration coefficients, NK, were determined for both chambers at the MKEH in August 2011 and before and after this at the IAEA Dosimetry Laboratory. The comparison ratio of the calibration coefficients normalized to the previous comparison results of the PTB and MKEH primary air kerma standards was in the range from 0.989 to 0.994 for the beam qualities used. The relative expanded (k = 2) uncertainty for each of these ratios is around 2%. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by EURAMET, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  18. Calculation of factors to convert from air kerma to absorbed dose to water for medium energy photons

    International Nuclear Information System (INIS)

    The IPEMB code of practice for the determination of absorbed dose for X-rays below 300 kV generating potential is a dedicated dosimetry protocol for the determination of absorbed dose based on the air kerma evaluation method for medium energy X-rays. Three separate energy ranges are dealt with in the code of practice, however, this report is only attempting to reproduce the factors in one particular range (0.5 - 4.0 nun Cu HVL) for X-rays generated at 135 and 280 kV. These X-ray qualities are used in the NPL therapy level calibration service. This new method includes the use of an air kerma calibration factor, NK, for the ionisation chamber, and the ratio of the mass-energy absorption coefficients of water to air and factors that account for the change in the response of a NE2561 ionisation chamber between calibration in air and measurement in a water phantom, kch, instead of the old F factor. This report describes the work that was undertaken to reproduce the product of the ratio of the mass-energy absorption coefficients of water to air and the kch factors. The majority of this work was carried out using Monte Carlo techniques based on the EGS4 code system. The factors calculated in this report were found to agree with values quoted in the IPEMB code of practice to within 4.2%. The quoted uncertainty for this work is 1.4% and the uncertainties for the factors quoted in the EPEMB code of practice are 3%. Hence this is reasonable agreement. Possible discrepancies in the values may be due either to limitations in the EGS4 code system, simplifications made in the chamber geometry or on the reliance on experimental data which is not quite applicable to its' use in this work. (author)

  19. Bilateral comparison COOMET.RI(I)-S2 of the air-kerma standards of the IAEA and the VNIIM, Russian Federation in medium energy x-rays

    International Nuclear Information System (INIS)

    A bilateral comparison has been made between the air-kerma standards of the IAEA and the VNIIM in the medium-energy x-ray range. The results show the standards to be in agreement at the level of the stated standard uncertainty for the comparison of 4.1 parts in 103. The comparison result, based on the calibration coefficients for a transfer chamber, is expressed as a ratio of the IAEA and the VNIIM standards for air kerma, suitable for entry in the BIPM key comparison database. (authors)

  20. Key comparison BIPM.RI(I)-K5 of the air kerma standards of the ININ, Mexico, and the BIPM in 137Cs gamma radiation

    International Nuclear Information System (INIS)

    A direct comparison of the standards for air kerma of the Instituto Nacional de Investigaciones Nucleares (ININ), Mexico, and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 137Cs radiation beam of the BIPM in February 2015. The comparison result, evaluated as a ratio of the ININ and the BIPM standards for air kerma, is 1.0048 with a combined standard uncertainty of 2.0 * 10-3. The results are analysed and presented in terms of degrees of equivalence for entry in the BIPM key comparison database. (authors)

  1. Comparison BIPM.RI(I)-K8 of high dose-rate Ir-192 brachytherapy standards for reference air kerma rate of the VSL and the BIPM

    DEFF Research Database (Denmark)

    Alvarez, J.T.; De Pooter, J.A.

    2014-01-01

    An indirect comparison of the standards for reference air kerma rate for 192Ir high dose rate brachytherapy sources of the Dutch Metrology Institute (VSL), The Netherlands, and of the Bureau International des Poids et Mesures (BIPM) was carried out at the VSL in November 2009. The comparison result, based on the calibration coefficients for a transfer standard and expressed as a ratio of the VSL and the BIPM standards for reference air kerma rate, is 0.9873 with a combined standard uncertainty of 0.0061.

  2. European inter-comparison of Monte Carlo codes users for the uncertainty calculation of the kerma in air beside a caesium-137 source

    International Nuclear Information System (INIS)

    Within the frame of the CONRAD European project (Coordination Network for Radiation Dosimetry), and more precisely within a work group paying attention to uncertainty assessment in computational dosimetry and aiming at comparing different approaches, the authors report the simulation of an irradiator containing a caesium 137 source to calculate the kerma in air as well as its uncertainty due to different parameters. They present the problem geometry, recall the studied issues (kerma uncertainty, influence of capsule source, influence of the collimator, influence of the air volume surrounding the source). They indicate the codes which have been used (MNCP, Fluka, Penelope, etc.) and discuss the obtained results for the first issue

  3. Dosimetric characteristics, air-kerma strength calibration and verification of Monte Carlo simulation for a new ytterbium-169 brachytherapy source

    International Nuclear Information System (INIS)

    Ytterbium-169 (169Yb) is a promising new isotope for brachytherapy with a half life of 32 days and an average photon energy of 93 KeV. It has an Ir-192-equivalent dose distribution in water but a much smaller half-value layer in lead (0.2 mm), affording improved radiation protection and customized shielding of dose-limiting anatomic structures. The goals of this study are to: (a) experimentally validate Monte Carlo photon transport dose-rate calculations for this energy range, (b) to develop a secondary air-kerma strength standard for 169Yb, and (c) to present essential treatment planning data including the transverse-axis dose-rate distribution and dose correction factors for a number of local shielding materials. Several interstitial 169Yb sources (type 6) and an experimental high dose-rate source were made available for this study. Monte Carlo photon-transport (MCPT) simulations, based upon validated geometric models of source structure, were used to calculate dose rates in water. To verify MCPT predictions, the transverse-axis dose distribution in homogeneous water medium was measured using a silicon-diode detector. For use in designing shielded applicators, heterogeneity correction factors (HCF) arising from small cylindrical heterogeneities of lead, aluminum, titanium, steel and air were measured in a water medium. Finally, to provide a sound experimental basis for comparing experimental and theoretical dose-rate distributions, the air-kerma strength of the sources was measured using a calibrated ion chamber. To eliminate the influence of measurement artifacts on the comparison of theory and measurement, simulated detector readings were compared directly to measured diode readings. The final data are presented in the format endorsed by the Interstitial Collaborative Working Group. 33 refs., 8 figs., 3 tabs

  4. Assessment of protocols in cone-beam CT with symmetric and asymmetric beams usingeffective dose and air kerma-area product.

    Science.gov (United States)

    Batista, Wilson Otto; Soares, Maria Rosangela; de Oliveira, Marcus V L; Maia, Ana F; Caldas, Linda V E

    2015-06-01

    This study aims to evaluate and compare protocols with similar purposes in a cone beam CT scanner using thermoluminescent dosimeter (TLD) and the air kerma-area product (PKA) as the kerma index. The measurements were performed on two protocols used to obtain an image of the maxilla-mandible using the equipment GENDEX GXCB 500: Protocol [GX1] extended diameter and asymmetric beam (14cm×8.5cm-maxilla/mandible) and protocol [GX2] symmetrical beam (8.5cm×8.5cm-maxillary/mandible). LiF dosimeters inserted into a female anthropomorphic phantom were used. For both protocols, the value of PKA was evaluated using a PTW Diamentor E2 meter and the multimeter Radcal Rapidose system. The results obtained for the effective dose/PKA were separated by protocol image. [GX1]: 44.5µSv/478mGycm(2); [GX2]: 54.8µSv/507mGycm(2). Although the ratio of the diameters (14cm/8.5cm)=1.65, the ratio of effective dose values (44.5µSv/54.8µSv)=0.81, that is, the effective dose of the protocol with extended diameter is 19% smaller. The PKA values reveal very similar results between the two protocols. For the cases where the scanner uses an asymmetric beam to obtain images with large diameters that cover the entire face, there are advantages from the point of view of reducing the exposure of patients when compared to the use of symmetrical beam and/or to FOV images with a smaller diameter. PMID:25620114

  5. Influence of photon energy spectra from brachytherapy sources on Monte Carlo simulations of kerma and dose rates in water and air

    International Nuclear Information System (INIS)

    Purpose: For a given radionuclide, there are several photon spectrum choices available to dosimetry investigators for simulating the radiation emissions from brachytherapy sources. This study examines the dosimetric influence of selecting the spectra for 192Ir, 125I, and 103Pd on the final estimations of kerma and dose. Methods: For 192Ir, 125I, and 103Pd, the authors considered from two to five published spectra. Spherical sources approximating common brachytherapy sources were assessed. Kerma and dose results from GEANT4, MCNP5, and PENELOPE-2008 were compared for water and air. The dosimetric influence of 192Ir, 125I, and 103Pd spectral choice was determined. Results: For the spectra considered, there were no statistically significant differences between kerma or dose results based on Monte Carlo code choice when using the same spectrum. Water-kerma differences of about 2%, 2%, and 0.7% were observed due to spectrum choice for 192Ir, 125I, and 103Pd, respectively (independent of radial distance), when accounting for photon yield per Bq. Similar differences were observed for air-kerma rate. However, their ratio (as used in the dose-rate constant) did not significantly change when the various photon spectra were selected because the differences compensated each other when dividing dose rate by air-kerma strength. Conclusions: Given the standardization of radionuclide data available from the National Nuclear Data Center (NNDC) and the rigorous infrastructure for performing and maintaining the data set evaluations, NNDC spectra are suggested for brachytherapy simulations in medical physics applications.

  6. Comparison BIPM.RI(I)-K8 of high dose-rate Ir-192 brachytherapy standards for reference air kerma rate of the VSL and the BIPM

    DEFF Research Database (Denmark)

    Alvarez, J.T.; De Pooter, J.A.; Andersen, Claus E.; Aalbers, A.H.L.; Allisy-Roberts, P. J .; Kessler, C.

    2014-01-01

    An indirect comparison of the standards for reference air kerma rate for 192Ir high dose rate brachytherapy sources of the Dutch Metrology Institute (VSL), The Netherlands, and of the Bureau International des Poids et Mesures (BIPM) was carried out at the VSL in November 2009. The comparison resu...

  7. Calculation of the correction factors for the primary standard of kerma in the air at the LNMRI-IRD, Rio de Janeiro, Brazil

    International Nuclear Information System (INIS)

    In order to determine the primary standardization in terms of kerma in the air, a graphite ionization chamber is used for calculation some correction factors. A program was elaborated, using the Monte Carlo Penelope for simulate the CC01-110 at the LNMRI/IRD, Rio de Janeiro, Brazil

  8. From Reference Air Kerma Rate to Nominal Absorbed Dose Rate to Water: Paradigm Shift in Photon Brachytherapy

    International Nuclear Information System (INIS)

    In brachytherapy (BT), photon radiation sources are presently calibrated in terms of the reference air kerma rate K? (or air kerma strength SK). By direct source calibration in terms of Dw,1, the nominal absorbed dose rate to water at the TG-43U1 reference position at 1 cm in water and with the ability to measure distributions of this quantity, the accuracy of clinical BT-dosimetry should increase due to decreased calibration uncertainties compared to present methods. Several Dw,1 primary standards are under development for high energy, high dose rate and low energy, low dose rate sources. To provide worldwide traceability and guidance for clinical medical physicists, an ISO standardization project, Clinical Dosimetry - Photon Radiation Sources Used in Brachytherapy, is considered, in continuation of ISO 21439 (2009) for beta sources. Clear terms and definitions are fundamental. Reclassification of BT-photon radiation qualities is also needed, introducing a range of medium energy photons with mean energies between 40 keV and 150 keV. Radionuclide BT-sources and electronic X ray BT-sources, BT-detectors and BT-phantoms should be characterized by sets of reference data, through which the clinical medical physicist could critically evaluate the data supplied by the manufacturer, prior to clinical application. Plastic scintillators have the potential for transfer standards of high accuracy and for verification measurements of BT-source output in phantoms. Based on and extending the AAPM TG-43U1 formalism, this planned ISO-standard will provide guidance for clinical BT-dosimetry in terms of absorbed dose to water and for estimating the uncertainties. (author)

  9. Reference dosimetry at the Australian Synchrotron's imaging and medical beamline using free-air ionization chamber measurements and theoretical predictions of air kerma rate and half value layer

    International Nuclear Information System (INIS)

    Purpose: Novel, preclinical radiotherapy modalities are being developed at synchrotrons around the world, most notably stereotactic synchrotron radiation therapy and microbeam radiotherapy at the European Synchrotron Radiation Facility in Grenoble, France. The imaging and medical beamline (IMBL) at the Australian Synchrotron has recently become available for preclinical radiotherapy and imaging research with clinical trials, a distinct possibility in the coming years. The aim of this present study was to accurately characterize the synchrotron-generated x-ray beam for the purposes of air kerma-based absolute dosimetry. Methods: The authors used a theoretical model of the energy spectrum from the wiggler source and validated this model by comparing the transmission through copper absorbers (0.1–3.0 mm) against real measurements conducted at the beamline. The authors used a low energy free air ionization chamber (LEFAC) from the Australian Radiation Protection and Nuclear Safety Agency and a commercially available free air chamber (ADC-105) for the measurements. The dimensions of these two chambers are different from one another requiring careful consideration of correction factors. Results: Measured and calculated half value layer (HVL) and air kerma rates differed by less than 3% for the LEFAC when the ion chamber readings were corrected for electron energy loss and ion recombination. The agreement between measured and predicted air kerma rates was less satisfactory for the ADC-105 chamber, however. The LEFAC and ADC measurements produced a first half value layer of 0.405 ± 0.015 and 0.412 ± 0.016 mm Cu, respectively, compared to the theoretical prediction of 0.427 ± 0.012 mm Cu. The theoretical model based upon a spectrum calculator derived a mean beam energy of 61.4 keV with a first half value layer of approximately 30 mm in water. Conclusions: The authors showed in this study their ability to verify the predicted air kerma rate and x-ray attenuation curve on the IMBL using a simple experimental method, namely, HVL measurements. The HVL measurements strongly supports the x-ray beam spectrum, which in turn has a profound effect on x-ray dosimetry.

  10. Distribution of kerma rate in the air inside of hemodynamic room for typical projections of interventionist cardiology procedures; Distribuicao da taxa de kerma no ar em uma sala de hemodinamica para projecoes tipicas de procedimentos de cardiologia intervencionista

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, Mirtha Elizabet Gamarra

    2008-07-01

    The evaluation of dose to physicians involved in Interventional Cardiology (IC) is an extreme important matter due to the high and non-uniform distribution of dose values. The radiation control during each procedure is complex and the reasons for the high exposures have many different causes. Many international recommendations have already been written aiming the radiation protection optimization in IC. In Brazil, there is not any special orientation for the protection of those occupational persons, nor a specific legislation. The purpose of this work is to evaluate the air kerma rate at critical anatomic regions of the occupationally exposed staff that carry out IC procedures, in representative incidences in order to give subsidies for individual monitoring procedures implementation and to give more information about their radiation protection. The air kerma rate has been measured in the often used condition in the two more common IC procedures namely angiography and coronary angioplasty, using an adult patient simulator irradiated under RAO, LAO and AP projections for fluoro and digital acquisition modes. The measurements have been made in 45 points around the examination table at 5 different representatives heights of: eyes lens, thorax, hands, gonads and knees. AP projection shows the smaller scattered radiation contributions and a more homogeneous exposure distribution. The digital acquisition mode gives air kerma rates about 4 times higher than fluoro mode for LAO projection in the position occupied by the interventionist doctor, the anesthetist and the nursing staff. The most critical anatomic regions are: knees and gonads (without protection). On the physician hands position, values as high as 5 mGy/h have been measured, which can overpass, depending on the number of procedures done, the individual occupational annual limit. Therefore, in IC it is necessary to implement additional protection tools, elaborate safety guides (based on international experiences and recommendations) and establish a permanent radiation protection training programs. (author)

  11. Calculation of the uncertainty associated to the result of entrance surface air kerma for conventional radiology patients

    International Nuclear Information System (INIS)

    Radiation doses from diagnostic radiology are the largest contribution to the collective dose and the use of guidance (reference levels) has proven to be a tool for optimization of protection. Recently, with the support of the International Atomic Energy Agency (IAEA), eight countries of the Latin-American region have been working together on a programme to test methodologies for determining preliminary values of guidance levels for X-ray chest, lumbar spine and breast examinations. The approach used was to obtain entrance surface air kerma from measurements of X-ray tube outputs, corrected for distance and backscatter and later for real exposure parameters used with patients. For quality control, some of these values for a reduced number of patients were compared with direct TLD measurements directly placed on the patient during exposure. Given the number of parameters involved in the two methods, relatively large differences are deemed to be found in the comparison. The only way of deciding if measurements and calculations are outliers, for example, due to a systematic error or a mistake, is to compare these differences with the combined uncertainty. The aim of this paper is to present (in a detailed way) the methodology used in the pilot program ARCAL LXXV, the analyses of data performed within the survey and the estimated uncertainty. The parameters analyzed were: precision of the readings, positioning of the detector, reproducibility of the mAs and kV, long term stability of the instrument, radiation quality, kerma rate, radiation incidence, field size and field homogeneity, calibration factor of the equipment, temperature and pressure measurement, X-ray tube output curve adjustment, backscatter factor and focus-patient distance. The combined standard uncertainty for Ke in chest radiography in adult patients of standard complexion, was 12%, and the expanded uncertainty (k=2) was 24%. (author)

  12. Development of a primary standard in terms of reference air kerma rate for 125I brachytherapy seeds

    International Nuclear Information System (INIS)

    The LNE-LNHB is currently developing the French primary standard in low dose rate brachytherapy. The method is based on a free-in-air ionization chamber for 125I seeds. Such sealed radioactive sources are used for treatment of ophthalmic and prostatic cancers. Low dose rate brachytherapy seeds are of small size, about 0.8 mm in diameter and 4.5 mm in length, cylindrically shaped and of complex internal design. This causes an anisotropy of emission in both planes, longitudinal and transverse. The reference air kerma rate is theoretically defined in this latter plane at a point positioned in a small volume of air at a one meter distance from the source center, the source and the air volume being surrounded by vacuum. To overcome the difficulties linked to a transversal anisotropic emission and to an expected low signal-to-noise ratio, a circular ring-shaped free-in-air ionization chamber has been designed. The 125I source seed is placed at the center of this ring detector in a tube of a low attenuated material. This paper presents an extended characterization of the circular ring-shaped free-in-air ionisation chamber. This one deals with the signal-to-noise ratio optimization, the detection volume assessment (taking into account the electric field distribution within it) and the sensitivity of the measurement linked to the source positioning. Furthermore, the correction factors to apply to the measurement results are described and their estimation using Monte Carlo codes of particle transport are presented for the Bebig iodine seed sources, referenced I125 S16

  13. European comparison of Monte Carlo codes users on the uncertainty calculations of air kerma determined in front of a cesium-137 beam

    International Nuclear Information System (INIS)

    Within the framework of the European project CONRAD (Coordinated Network for Radiation Dosimetry, contract FP6-12684) coordinated by EURADOS (European Radiation Dosimetry group), WP4 was devoted to numerical dosimetry under the title 'Uncertainty assessment in computational dosimetry: an intercomparison of approaches'. Within this activity, a working group sent a list of eight exercises, dealing with radiation transport of photons, neutrons, protons and electrons, to be solved by the international community. This paper presents exercise number 4, dealing with the calculation of air kerma for a 137Cs beam. This problem was aimed at estimating the components of the uncertainty on the air kerma which cannot be measured, namely those due to geometrical data such as the source location, the diameter of the collimator, the material density, etc. 12 institutes of 10 different countries took part in this work, showing the interest in this proposal. (authors)

  14. Bilateral comparison COOMET.RI(I)-S2 of the air-kerma standards of the IAEA and the VNIIM, Russian Federation in medium energy x-rays

    Science.gov (United States)

    Czap, L.; Gomola, I.; Oborin, A. V.; Villevalde, A. Y.

    2014-01-01

    A bilateral comparison has been made between the air-kerma standards of the IAEA and the VNIIM in the medium-energy x-ray range. The results show the standards to be in agreement at the level of the stated standard uncertainty for the comparison of 4.1 parts in 103. The comparison result, based on the calibration coefficients for a transfer chamber, is expressed as a ratio of the IAEA and the VNIIM standards for air kerma, suitable for entry in the BIPM key comparison database. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  15. Comparison BIPM.RI(I)-K8 of high dose-rate Ir-192 brachytherapy standards for reference air kerma rate of the NMIJ and the BIPM

    Science.gov (United States)

    Kessler, C.; Kurosawa, T.; Mikamoto, T.

    2016-01-01

    An indirect comparison of the standards for reference air kerma rate for 192Ir high dose rate (HDR) brachytherapy sources of the National Metrology Institute of Japan (AIST-NMIJ), Japan, and of the Bureau International des Poids et Mesures (BIPM) was carried out at the Japan Radioisotope Association (JRIA) in April 2015. The comparison result, based on the calibration coefficients for a transfer standard and expressed as a ratio of the NMIJ and the BIPM standards for reference air kerma rate, is 1.0036 with a combined standard uncertainty of 0.0054. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  16. Key comparison BIPM.RI(I)-K5 of the air-kerma standards of the PTB, Germany and the BIPM in 137Cs gamma radiation

    Science.gov (United States)

    Kessler, C.; Burns, D. T.; Büermann, L.

    2014-01-01

    A direct comparison of the standards for air kerma of the Physikalisch-Technische Bundesanstalt (PTB), Germany and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 137Cs radiation beam of the BIPM in March 2014. The comparison result, evaluated as a ratio of the PTB and the BIPM standards for air kerma, is 1.0024 with a combined standard uncertainty of 2.7 × 10-3. The results are analysed and presented in terms of degrees of equivalence for entry in the BIPM key comparison database. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  17. Key comparison BIPM.RI(I)-K1 of the air-kerma standards of the PTB, Germany and the BIPM in 60Co gamma radiation

    Science.gov (United States)

    Kessler, C.; Burns, D. T.; Büermann, L.

    2014-01-01

    A direct comparison of the standards for air kerma of the Physikalisch-Technische Bundesanstalt (PTB), Germany and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 60Co radiation beam of the BIPM in March 2014. The comparison result, evaluated as a ratio of the PTB and the BIPM standards for air kerma, is 1.0036 with a combined standard uncertainty of 1.7 × 10-3. The results are analysed and presented in terms of degrees of equivalence for entry in the BIPM key comparison database. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  18. Comparison BIPM.RI(I)-K8 of high dose-rate Ir-192 brachytherapy standards for reference air kerma rate of the PTB and the BIPM

    Science.gov (United States)

    Kessler, C.; Allisy-Roberts, P. J.; Selbach, H. J.

    2015-01-01

    An indirect comparison of the standards for reference air kerma rate (RAKR) for 192Ir high dose rate (HDR) brachytherapy sources of the Physikalisch-Technische Bundesanstalt (PTB), Germany, and of the Bureau International des Poids et Mesures (BIPM) was carried out at the PTB in September 2011. The comparison result, based on the calibration coefficients for a transfer standard and expressed as a ratio of the PTB and the BIPM standards for reference air kerma rate, is 1.0003 with a combined standard uncertainty of 0.0099. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  19. Comparison of the air-kerma standards of the ENEA-INMRI and the BIPM in the low-energy X-ray range

    International Nuclear Information System (INIS)

    A direct comparison has been made between the air-kerma standards of the ENEA-INMRI and the BIPM in the low-energy x-ray range. The results show the standards to be in agreement to around 0.35 % at reference beam qualities up to 50 kV. Measurements were also made at the 80 kV quality in order to estimate the electron-loss correction for the ENEA standard at this quality. (authors)

  20. Measuring instruments of the Physikalisch-Technische Bundesanstalt for realization of the units of the dosimetric quantities standard ion dose, photon-equivalent dose and air-kerma

    International Nuclear Information System (INIS)

    The realization of the units of the dosimetric quantities exposure, air-kerma and photon-equivalent dose is an important task of the Physikalisch-Technische Bundesanstalt. The report describes the measuring instruments and other technical equipment as well as the determination of the numerous corrections needed. All data and correction factors required for the realization of the units mentioned above are given in many diagrams and tables. (orig.)

  1. Key comparison BIPM.RI(I)-K7 of the air-kerma standards of the BEV, Austria and the BIPM in mammography x-rays

    International Nuclear Information System (INIS)

    A first key comparison has been made between the air-kerma standards of the BEV and the BIPM in mammography x-ray beams. The results show the standards to be in agreement at the level of the combined standard uncertainty of 3.4 parts in 103. The results are analysed and presented in terms of degrees of equivalence for entry in the BIPM key comparison database. (authors)

  2. Key comparison BIPM.RI(I)-K2 of the air-kerma standards of the BEV, Austria and the BIPM in low-energy x-rays

    International Nuclear Information System (INIS)

    A key comparison has been made between the air-kerma standards of the BEV and the BIPM in the low-energy x-ray range. The results show the standards to be in agreement at the level of the combined standard uncertainty of 4.7 parts in 103. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. (authors)

  3. Key comparison BIPM.RI(I)-K2 of the air-kerma standards of the NMIJ, Japan and the BIPM in low-energy x-rays

    International Nuclear Information System (INIS)

    A key comparison has been made between the air-kerma standards of the NMIJ and the BIPM in the low-energy x-ray range. The results show the standards to be in agreement at the level of the standard uncertainty for the comparison of 3.0 parts in 103. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. (authors)

  4. Key comparison BIPM.RI(I)-K3 of the air-kerma standards of the BEV, Austria and the BIPM in medium-energy x-rays

    International Nuclear Information System (INIS)

    A key comparison has been made between the air-kerma standards of the BEV, Austria and the BIPM in the medium-energy x-ray range. The results show the standards to be in general agreement at the level of the expanded uncertainty (k = 2) of the comparison of 6.4 parts in 103. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. (authors)

  5. Comparison of the air kerma standards of the IAEA and the BIPM in mammography x-rays

    International Nuclear Information System (INIS)

    The Dosimetry Laboratory of the International Atomic Energy Agency (IAEA), Seibersdorf, Austria, calibrates reference standards in mammography x-ray beams for IAEA/WHO SSDL Network members (more than 80 laboratories worldwide). As a signatory of the Mutual Recognition Arrangement (CIPM MRA), the IAEA laboratory maintains a Quality Management System (QMS) complying with ISO 17025 and requires updated 'supporting evidence' for its dosimetry calibration and measurement capabilities (CMC), first published in Appendix C of the CIPM MRA key comparison database in 2007. For this purpose, an indirect comparison has been made between the air kerma standards of the IAEA and the Bureau International des Poids et Mesures (BIPM) in the mammography x-ray range from 25 kV to 35 kV, using as transfer instruments two thin-window parallel-plate ionization chambers belonging to the IAEA. The IAEA and BIPM standards for mammography x-rays are shown to be in agreement within the standard uncertainty of the comparison of 5.5 parts in 103. This agreement can be used to support the calibration and measurements capabilities of the IAEA listed in Appendix C of the key comparison database. (authors)

  6. Monte Carlo aided room scatter studies in the primary air kerma strength standardization of a remote afterloading 192Ir HDR source

    International Nuclear Information System (INIS)

    Corrections for room scatter, [ksc(d, H)]RM, were derived using Monte Carlo methods for rooms of various sizes, including the brachytherapy treatment room, in which primary air kerma strength standardization of a remote afterloading microSelectron 192Ir HDR source was carried out, using a 60 cm3 spherical graphite ion chamber. It was observed that for a given source-to-floor height, H, the air kerma rate due to room scatter was found to be decreasing with increase in source-to-detector distance, d, whereas it is assumed to be constant in the experimental determination (multiple-distance method) of the air kerma strength (AKS). Irrespective of the room size considered in the present study and when H=100 cm, the assumption of 'constant room scatter' for d=50, 75 and 100 cm resulted in overestimation of the AKS by about 1%. However, when d was in the range 13-25 cm, it was only 0.20%. The room scatter correction for the shadow cone method was also computed and the result showed that no additional correction was required on account of forward scatter from the cone. Further, at larger d (50-100 cm), the number of low-energy photons (40-200 keV) relative to the total number of photons was found to be very significant, which may be useful to revisit the Spencer-Attix cavity theory. (author)

  7. Spatial distribution of air kerma rate and impact of accelerating voltage on the quality of an ultra soft X-ray beam generated by a cold cathode tube in air

    International Nuclear Information System (INIS)

    Ultrasoft X-ray characteristic aluminum K alpha line (Al K? with energy of 1.5 keV) is used in radiobiological experiments to study the effect of radiation on biological matter. A simple method to generate a continuous beam of those X-ray radiations is to bombarding an aluminum target with accelerated electrons using high voltage (HV). In this work, by varying the HV we study the characteristics of a photon beam generated by means of a cold cathode transmission X-ray tube. The anode is a thin (16 ?m) aluminum foil supported by a copper grid. The spatial distribution of air kerma is measured using gafchromic films of HD-810 calibrated with a parallel plate free-air ionization chamber. We show that HV strongly modifies the energetic spectrum and air kerma rate as well as its uniformity and intensity in air. - Highlights: • We measured energy spectrum of X-ray beam. • We calibrate the Gafchromic films to measure air kerma of X-ray beam. • Spatial air kerma rate is determined and interpreted. • We define dimensions and position of future biological sample irradiation using Al K? X-ray

  8. Evaluation of entrance skin air kerma in digital and conventional pediatric chest examinations performed in Parana-Brazil

    International Nuclear Information System (INIS)

    Full text: In pediatric radiology it is important to evaluate patient exposure due to the high sensitivity of his/her tissue and his/her relatively longer life expectancy, which may increase the chance of radiogenic cancer development. Special attention is necessary when digital systems are used since a high dosage level for the patient may go unnoticed because the resulting image is not overexposed. The purpose of this work is to evaluate the Entrance Skin Air Kerma (ESAK) in pediatric patients submitted to digital and conventional chest examinations performed in the State of Parana, located in the Southern region of Brazil. The survey was performed in two hospitals, one located in Curitiba, the Capital of the State (A) and the other in the city of Cascavel (B). Hospital A uses a conventional image system and Hospital B uses a CR digital system. The study group consisted of 50 patients (from 2 days to six years of age) undergoing chest PA/AP examinations. At the time of the examination, the exposure parameters (kV, mAs, focal-film distance, etc) and the gender, height, weight and age of the patient were recorded. To evaluate the Entrance Skin Air Kerma (ESAK), two TLD-100 dosimeters were packaged in a polyethylene case, heat sealed and placed on the surface of each patient. The TLDs were calibrated the Metrology Laboratory of Ionizing Radiation of the Federal University of Pernambuco. The TLDs were processed on a Victoreen readout system model 2800M. The results showed that the kilovoltage values used in Hospital A are in the range of 46 to 65 kV with the average value of 51,7 kV, while the ones in Hospital B are in the range of 65 to 80 kV. On the other hand, even though hospital B uses the CR system, the mAs used for the chest exams are 4 times higher than the ones used in Hospital A. For Hospital A, the mean ESAK value was 0.044 mGy (min: 0.08 and max 0.146 mGy), and for Hospital B the mean ESAK value was 0.368 mGy (min: 0.021 and max 1.21mGy). The results made it clear that the pediatric chest images produced with the digital system are not optimized and the doses are very high when compared with the film system. It is possible to conclude that the introduction of advanced technologies in the radiographic clinics not necessary represents a reduction of the patient dose. Reduction of patient dose requires optimization of the whole imaging chain, and this includes the information for the technicians. (author)

  9. Comparison of the air kerma standards of the IAEA and the BIPM in mammography x-rays

    Science.gov (United States)

    Kessler, C.; Burns, D. T.; Czap, L.; Csete, I.; Gomola, I.

    2013-01-01

    The Dosimetry Laboratory of the International Atomic Energy Agency (IAEA), Seibersdorf, Austria, calibrates reference standards in mammography x-ray beams for IAEA/WHO SSDL Network members (more than 80 laboratories worldwide). As a signatory of the Mutual Recognition Arrangement (CIPM MRA), the IAEA laboratory maintains a Quality Management System (QMS) complying with ISO 17025 and requires updated 'supporting evidence' for its dosimetry calibration and measurement capabilities (CMC), first published in Appendix C of the CIPM MRA key comparison database in 2007. For this purpose, an indirect comparison has been made between the air kerma standards of the IAEA and the Bureau International des Poids et Mesures (BIPM) in the mammography x-ray range from 25 kV to 35 kV, using as transfer instruments two thin-window parallel-plate ionization chambers belonging to the IAEA. The IAEA and BIPM standards for mammography x-rays are shown to be in agreement within the standard uncertainty of the comparison of 5.5 parts in 103. This agreement can be used to support the calibration and measurements capabilities of the IAEA listed in Appendix C of the key comparison database. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  10. Air kerma national standard of Russian Federation for x-ray and gamma radiation. Activity SSDL/VNIIM in medical radiation dosimetry field

    International Nuclear Information System (INIS)

    Primary standard of unities air kerma and air kerma rate X-ray and gamma radiation, placed at VNIIM, consists of: plate-parallel free-air ionization chamber IK 10-60 for low-energy X-ray in the generating potential range from 10 to 50 kV; plate-parallel free-air ionization chamber IK 50-400 for medium-energy X-ray in the generating potential range from 50 to 300 kV; cavity cylindrical graphite chambers C1 and C30 with volumes 1 cm3 and 30 cm3 for reproduction and transmission the dimensions gamma radiation unities using Cs-137 and Co-60 sources. The next irradiation facilities are used at VNIIM: in low-energy X-ray range: a constant-potential high-voltage generator and a tungsten-anode Xray tube with inherent filtration of around 1 mm Be; in medium-energy X-ray range: set on the basis of an industrial X-ray apparatus Isovolt-400 and a tungsten-anode X-ray tube with inherent filtration of around 3,5 mm Al; in gamma radiations field: units with a radioactive sources Cs-137 with activity 140 and 1200 GBq and Co-60 with activity 120 GBq and irradiation set with a source from Co-60 (activity 3200 GBq). The last one belongs to Central Research Institute for Radiology and Roentgenology (CNIRRI). For measuring currents and charges of standard chambers we use electrometers such as Keithley of model 6517A and B7-45 manufactured by 'Belvar' (Republic Belarus). The reference radiation qualities L, N, H series according to ISO 4037 and the radiation qualities RQR, RQA and RQF according to IEC 61267 for calibration and verification of the therapeutic, diagnostic measurement means are realized in the low-energy and medium-energy X-ray standards. The VNIIM air kerma primary standard of has been participated in the international comparisons: key comparison BIPM.R1(I)-K1 for gamma radiation of Co-60 in 1997; supplementary comparisons BIPM.R1(I)-S10 for gamma radiation of Cs-137 in 1997; key comparison BIPM.R1(I)-K2 for low-energy X-ray range in 1998; key comparison BIPM.R1(I)-K3 for medium-energy X-ray range in 1998. The results of comparisons are presented in the table 1. Dimensions of unities of air kerma and air kerma rate are transmitted from primary standard to secondary standards with expanded uncertainty from 1,3 to 2,5 % (k=2), which are including and at laboratory SSDL/VNIIM and base dosimetry laboratory CNIRRI. The comparisons of secondary standards with the primary standard VNIIM are performed one time in 5 years. The laboratory SSDL/VNIIM is the component of state primary standards laboratory in the field of measurement ionizing radiations VNIIM. SSDL/VNIIM has the secondary standard - universal dosimeter UNIDOS with ionization chambers of volume from 0,6 cm3 to 10 liters, radioactive sources from Fe-55, Cd-109, Am-241, Cs-137 and Co-60 with activity from 0,03 to 140 GBq. The primary standard equipment and facility on the basis industrial X-ray apparatus YRD-1 with a tungsten-anode X-ray tube and inherent filtration of around 3 mm Al (at generating potential from 50 to 250 kV) are used for calibration dosimetric devices in the field X-ray. There is termoluminescence dosimetric system such as KDT-02M with TL detectors from LiF for spending audit measurements by method 'dose-post'. Laboratory SSDL/VNIIM and base dosimetric laboratory CNIRRI are carried out calibrations and verifications of air kerma and air kerma rate reference standards and working measurement means for X-ray and gamma therapy and diagnostics, belonging to the oncology and diagnostic centers, clinics and hospitals. The laboratory CNIRRI fulfils the verification of measurement means and supervision of the application in the medical radiology, but the regional departments of radial diagnostics put into practice monitoring of doses, obtained by patients and staff at fulfilling of diagnostic and medical procedures. The diagnostic and clinical dosimeters are calibrated directly under the primary standard of air kerma and air kerma rate for achievement the highest accuracy. At 2000-2001 this calibrations were carried out for the Belarusian Research Institute of Oncol

  11. Comparison of the air-kerma standards of the NPL and the BIPM in the low and medium-energy X-ray ranges

    International Nuclear Information System (INIS)

    The air-kerma standards of the NPL and the BIPM have been compared in the low- and medium-energy x-ray ranges. The results for the low-energy comparison show the standards to be in agreement at the level of one standard uncertainty. At medium energies a slight trend with radiation quality is evident, with agreement at the level of one standard uncertainty for 100 kV rising to over two standard uncertainties for 250 kV. In relation to previous comparisons, the good stability of the standards over a period of twenty years is demonstrated. (authors)

  12. Revised comparison of the standards for air kerma of the ENEA-INMRI and the BIPM for 60Co gamma rays

    International Nuclear Information System (INIS)

    In 1998 a comparison of the standards of air kerma of the Istituto Nazionale di Metrologia delle Radiazioni Ionizzanti of the Ente per le Nuove Tecnologie, l'Energia e l'Ambiente, Italy (ENEA-INMRI) and of the Bureau International des Poids et Mesures (BIPM) was carried out in 60Co radiation. The comparison result, declared in 2003, is 1.0044 (0.0026) and demonstrates that the ENEA-INMRI and BIPM standards are in agreement within the expanded uncertainty (k = 2). (authors)

  13. Comparison of the air kerma standards of the NIST and the BIPM in the low-energy X-ray range

    International Nuclear Information System (INIS)

    A direct comparison has been made between the air-kerma standards of the NIST and the BIPM in the low-energy x-ray range. The results show the standards to be in agreement to around 0.5 % at reference beam qualities up to 50 kV and at 100 kV. Agreement at the 80 kV quality is less satisfactory, which may be attributed to an incorrect value for the electron-loss correction for the NIST standard at this quality. (authors)

  14. Proposed specification for a primary standard of air kerma for sup 6 sup 0 Co, sup 1 sup 3 sup 7 Cs and sup 1 sup 9 sup 2 Ir gamma-ray sources

    CERN Document Server

    Angliss, R; Nutbrown, R

    2001-01-01

    The three cavity chambers, the mean response of which constitutes the primary standard of air kerma for sup 6 sup 0 Co and sup 1 sup 3 sup 7 Cs gamma-rays in the United Kingdom, have been in continuous, almost daily, use at the National Physical Laboratory (NPL) since 1956. These chambers were initially designed for use with 2 MV X-rays at therapy level air kerma rates. However since 1978 they have also been used for protection level air kerma rates, initially, with X-rays generated at 1 MV and 2 MV and more recently with sup 6 sup 0 Co and sup 1 sup 3 sup 7 Cs gamma-rays. They have been used for therapy level air kerma calibrations with sup 6 sup 0 Co gamma-rays since 1997 following the demise of the NPL 2 MV Van de Graaff generator. This report describes the proposals for a new primary standard and the methods that will be used to give a better performance than the present standard when used with air kerma rates from as high as 1 Gy min sup - sup 1 down to 10 mGy hr sup - sup 1. The design will also seek to...

  15. Construction of a laboratory for the implantation of primary standardization of the magnitude kerma in the air for the X-ray beams used in mammography; Construcao de um laboratorio para a implantacao da padronizacao primaria da grandeza kerma no ar para os feixes de raios X empregados em mamografia

    Energy Technology Data Exchange (ETDEWEB)

    Cardozo, W.L.; Magalhes, L.A.A.M.F.; Peixoto, J.G.P., E-mail: wagnerlc@ird.gov.b [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil). Lab. Nacional de Metrologia das Radiacoes Ionizantes (LNMRI)

    2009-07-01

    Aiming to diminish the uncertainty in each phase of the metrological chain, and the uncertainty in dosimetry processed at the X-ray beam applied in the mammography, is necessary that the LNMRI/IRD to develop a reference primary standard for the absolute form to the magnitude kerma in the air

  16. Calculation of the correction factors for the primary standard of kerma in the air at the LNMRI-IRD, Rio de Janeiro, Brazil; Calculo de fatores de correcao para o padrao primario em kerma no ar do LNMRI-IRD, Rio de Janeiro, Brasil

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Cosme Norival Mello da, E-mail: cosme@ird.gov.b [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil). Lab. Nacional de Metrologia das Radiacoes Ionizantes (LNMRI)

    2009-07-01

    In order to determine the primary standardization in terms of kerma in the air, a graphite ionization chamber is used for calculation some correction factors. A program was elaborated, using the Monte Carlo Penelope for simulate the CC01-110 at the LNMRI/IRD, Rio de Janeiro, Brazil

  17. Calculation of conversion factor of Kerma in the air for ambient dose equivalent in radiotherapy; Calculo dos fatores de conversao de Kerma no ar para equivalente de dose ambiental em radioterapia

    Energy Technology Data Exchange (ETDEWEB)

    Lima, Marco Antonio Frota

    2000-03-01

    This work aims to estimate the average conversion factor of Kerma in air to H {sup *} (10) using photon beams coming from clinic linear accelerators, transmitted through concrete walls of a radiotherapic treatment room. The transmitted photon spectra by both 1 meter and 2 meters concrete walls, in an area of 40 x 40 cm{sup 2}, were calculated when the primary beam impart in an angle of 0 deg. The (secondary) photon beams transmitted respectively by 0,5 meter, 1,0 meter, 1,0 meter and 2,0 meter concrete walls, after they scattered by an angle of 90 deg in a cylindric phantom inside the room, were also determined. Generally, 50 millions of histories were computed for each simulation made for the primary beam. For the 90 deg spread, the number of histories was 100 millions. The computational code used on this work was the MCNP4B. The most common clinic accelerators used on radiotheraphic treatments were used on this work CLINAC-4, CLINAC-6, CLINAC-18 and CLINAC-2500. From the spectra analysis obtained in this work, it was possible to dispose the conversion factor for realistic beams found in radiotherapeutic establishment. (author)

  18. Kerma in the air at entry surface in thorax pediatric examinations at public hospital in Parana, Brazil; Kerma no ar na superficie de entrada em exames pediatricos de torax em hospital publico no Parana, Brasil

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Amanda; Porto, Lorena; Bunick, Ana; Paschuk, Sergei; Denyak, Valeriy, E-mail: schelin@utfpr.edu.b [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil); Schelin, Hugo; Tilly, Joao, E-mail: joao.tilly@derax.com.b [DERAX Desenvolvimento Radiologico, Curitiba, PR (Brazil); Khoury, Helen, E-mail: hjkhoury@gmail.co [Universidade Federal de Pernambuco (DOIN/UFPE), Recife, PE (Brazil). Dept. de Energia Nuclear. Grupo de Dosimetria e Instrumentacao Nuclear; Ferreira, Jose [Universidade Estadual do Oeste do Parana (UNIOESTE), Cascavel, PR (Brazil)

    2011-07-01

    This work consisted in the evaluation of the entrance skin air kerma (ESAK) in pediatric chest x-ray examinations. A study of 186 exams in anterior-posterior, posterior-anterior and lateral projections was carried out for patients with ages ranging from 0 to 15 years. The ESAK was measured with the DoseCal software and Li-Fl thermoluminescent dosimeters. The results were compared with measurements done recently at the same place and with the reference dose values established by the European Community. It was observed that the optimization of the technique and the routine changes suggested in the previous study were not maintained. The charge (mAs) and the ESAK values found in the present study were much higher than the previous one, and the voltage (kVp) values found was lower. The results suggest that the implementation of the Quality Assurance Program could adequate these parameters to the established levels and keep the pediatric examinations more uniform. (author)

  19. Estimation of mean-glandular dose from monitoring breast entrance skin air kerma using a high sensitivity metal oxide semiconductor field effect transistor (MOSFET) dosimeter system in mammography

    International Nuclear Information System (INIS)

    Estimation of mean-glandular dose (MGD) has been investigated in recent years due to the potential risks of radiation-induced carcinogenesis associated with the mammographic examination for diagnostic radiology. In this study, a new technique for immediate readout of breast entrance skin air kerma (BESAK) using high sensitivity MOSFET dosimeter after mammographic projection was introduced and a formula for the prediction of tube output with exposure records was developed. A series of appropriate conversion factors was applied to the MGD determination from the BESAK. The study results showed that signal response of the high sensitivity MOSFET exhibited excellent linearity within mammographic dose ranges, and that the energy dependence was less than 3% for each anode/filter combination at the tube potentials 25-30 kV. Good agreement was observed between the BESAK and the tube exposure output measurement for breasts thicker than 30 mm. In addition, the air kerma estimated from our prediction formula provided sufficient accuracy for thinner breasts. The average MGD from 120 Asian females was 1.5 mGy, comparable to other studies. Our results suggest that the high sensitivity MOSFET dosimeter system is a good candidate for immediately readout of BESAK after mammographic procedures

  20. Comparisons of the standards for air kerma of the PTB and the BIPM for 60Co and 137Cs gamma radiation

    International Nuclear Information System (INIS)

    Direct comparisons of the standards for air kerma of the Physikalisch-Technische Bundesanstalt (PTB, Germany) and of the Bureau International des Poids et Mesures (BIPM) were carried out in the 60Co and 137 Cs radiation beams of the BIPM in 2000. The results, expressed as ratios of the PTB and the BIPM standards for air kerma, indicate a relative difference in 60Co of 9.9 x 10-3 with a combined standard uncertainty of 1.8 x 10-3, and in 137Cs of 6.4 x 10-3 with a combined standard uncertainty of 2.8 x 10-3. The earlier comparisons in 60Co γ rays made in 1971 (direct) and 1989 (indirect) resulted in an agreement of the two standards within 2 x 10-3. The differences obtained now are due to the application of new correction factors for wall effects and point source non-uniformity of the beam, kwall and kpn, for the PTB standards, which were calculated using Monte Carlo methods. (authors)

  1. Intercomparison of absorbed dose to water and air-kerma based dosimetry protocols for photon and electron beams

    International Nuclear Information System (INIS)

    Full text: During the last three decades the International Atomic Energy Agency (IAEA), the American Association of Physicists in Medicine (AAPM) and organizations from various countries have published Codes of Practice (CoP) and dosimetry protocols for the calibration of high-energy photon and electron beams. They are based on the air-kerma or exposure calibration factor of an ionization chamber in a 60Co gamma ray beam and formalism for the determination of absorbed dose to water in reference conditions. In recent years, the IAEA (IAEA TRS-398) and the AAPM (AAPM TG-51) have published new external beam dosimetry protocols that are based on the use of an ionization chamber calibrated in terms of absorbed dose to water in a standards laboratory's reference quality beam. These two new protocols follow those by the German Standard DIN, the British IPSM and the IAEA CoP for plane-parallel chambers, which have discussed and implemented the procedures for the determination of absorbed dose-to-water based on standards of absorbed dose-to-water. Since the publication of these protocols and CoPs, many comparisons, theoretical as well as experimental, between them have been published in the literature providing valuable information about the sources of similarities and discrepancies that exist among them. For example, the differences in the basic data for photon and electron beams included in the various IAEA CoPs are very small for the second edition of TRS-277 for photons, TRS-381 for electrons and TRS-398. In these cases the data changes posed by the adoption of TRS-398 are within about ±0.3% for the most commonly used energies. When implementing TRS-398 in these cases, the main difference will arise from the transition from Kair to Dw standards. For example, experimental comparison of absorbed doses between TRS-398 and TRS-277 for photons show an average difference of about 0.3% for most commonly used energies with a maximum difference of about 1% at a TPR20,10 value of 0.80; for electrons a maximum difference of about 1% is observed between TRS-398 and TRS-381 and about 1.8% between TRS-398 and TRS277 for energies ranging from 6-18 MeV. The comparison of TRS-398 with TG-51 reveals that photon beam dosimetry agrees within about ±0.3% for most commonly used energies. For electron beam dosimetry, comparison of TRS-398 with TG-51 reveals agreement within about ±0.4% for cylindrical chambers for energies above 10 MeV approximately; however, for plane-parallel chambers, differences of almost up to 2% is observed between the two protocols. On the other hand, the agreement for these chambers when cross-calibration procedures are used is excellent. This talk will provide a comprehensive review of intercomparisons of all these protocols. The reasons for the discrepancies between theory and experiments will be discussed terms of the combined effect of small data differences and the influence of ND,w/NK for the various chamber types. (author)

  2. Investigation of photon spectra and contributions to air kerma rates in the environment near nuclear facilities using portable germanium gamma spectrometry

    International Nuclear Information System (INIS)

    Portable spectrometers based on NaI or Ge detectors are now important additions to the tools available for monitoring and assessment of radioactivity and radiation dose rates in the environment due to both natural and anthropogenic sources. The high resolution of the Ge detector is of particular use in rapidly identifying and assessing radionuclides of significance. Portable spectrometry is of importance in assessing deposited activity and contributions to air kerma rates, and the rapid availability of these results would be significant in the event of a nuclear emergency in addition to the more usual application of measuring concentrations of radionuclides in environmental samples. In the course of developing a portable germanium detector system, spectra were measured at a number of locations in the environment near nuclear establishments in the UK. These spectra are presented and analysed in this paper in terms of the radionuclide contributions and gamma air kerma rates. Particular features are highlighted. First, background contributions are characterised using an example spectrum measured at Lowestoft beach, where anthropogenic influences are low. By contrast, near the Magnox nuclear power station at Bradwell, Essex there are contributions to the spectra due to photons from 16N, 41Ar and 60Co. In the Ravenglass estuary near Sellafield, 137Cs features prominently, with smaller contributions due to other radionuclides discharged in liquid waste from Sellafield. In the Ribble estuary which is influenced by discharges from the Springfields fuel fabrication plant as well as from Sellafield, measurements were made on a houseboat at high and low tide; there was a significant difference in the contribution due to 137Cs from Sellafield. Upstream of the Springfields works, peaks in the spectrum were observed due to 234Th and 234mPa due to discharges from the site, as well as 137Cs from BNFL Sellafield. The paper highlights and comments on all these features. In addition, the spectra were analysed in terms of contributions to gamma air kerma rates and the components due to natural background. Dose rates to members of the public who may spend time at the relevant locations are well within the dose limit of 1 mSv per year recommended by the ICRP. The different contributions to dose rates are contrasted. By highlighting particular features, this study demonstrates the wide range of applications of portable Ge spectrometry in environmental situations. (author)

  3. KEY COMPARISON Comparison of the standards of air kerma of the ENEA-INMRI and the BIPM for 137Cs gamma rays

    Science.gov (United States)

    Allisy-Roberts, P. J.; Kessler, C.; Toni, M.; Bovi, M.

    2010-01-01

    A comparison of the standards of air kerma of the Istituto Nazionale di Metrologia delle Radiazioni Ionizzanti of the Ente per le Nuove Tecnologie, l'Energia e l'Ambiente, Italy (ENEA-INMRI) and of the Bureau International des Poids et Mesures (BIPM) was carried out in 137Cs radiation in 1998. The comparison result, updated for changes in the standards in 2003 and 2009, is 0.9927 (0.0067) and demonstrates that the ENEA-INMRI and BIPM standards are in agreement within the uncertainties. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI Section I, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  4. Comparison of the air kerma standards for {sup 137}Cs and {sup 60}Co gamma-ray beams between the IAEA and the NIST

    Energy Technology Data Exchange (ETDEWEB)

    Minniti, R. [National Institute of Standards and Technology (NIST), Gaithersburg, MD (United States); Czap, L. [International Atomic Energy Agency (IAEA) Vienna (Austria)

    2011-04-15

    A comparison of the air kerma standards for {sup 137}Cs and {sup 60}Co gamma ray beams was performed between the NIST and the IAEA. Two reference class ionization chambers owned by the IAEA were used as part of this comparison and were calibrated at each facility. The calibration coefficients, N{sub K}, were determined for both chambers and in both gamma-ray beams. The measurements were performed at the IAEA and NIST facilities starting in the fall of 2009 and were completed in 2010. The comparison ratio of the calibration coefficients for each chamber, N{sub K,} {sub IAEA} / N{sub K,} {sub NIST}, between the IAEA and NIST were 0.999 and 0.997 for the {sup 137}Cs and {sup 60}Co gamma ray beams respectively. The relative standard uncertainty for each of these ratios is 0.5 %. (authors)

  5. Comparison of the air kerma standards for 137Cs and 60Co gamma-ray beams between the IAEA and the NIST

    International Nuclear Information System (INIS)

    A comparison of the air kerma standards for 137Cs and 60Co gamma ray beams was performed between the NIST and the IAEA. Two reference class ionization chambers owned by the IAEA were used as part of this comparison and were calibrated at each facility. The calibration coefficients, NK, were determined for both chambers and in both gamma-ray beams. The measurements were performed at the IAEA and NIST facilities starting in the fall of 2009 and were completed in 2010. The comparison ratio of the calibration coefficients for each chamber, NK,IAEA / NK,NIST, between the IAEA and NIST were 0.999 and 0.997 for the 137Cs and 60Co gamma ray beams respectively. The relative standard uncertainty for each of these ratios is 0.5 %. (authors)

  6. Determination of the Kwall correction factor for a cylindrical ionization chamber to measure air-kerma in 60Co gamma beams

    International Nuclear Information System (INIS)

    The factor Kwall to correct for photon attenuation and scatter in the wall of ionization chambers for 60Co air-kerma measurement has been traditionally determined by a procedure based on a linear extrapolation of the chamber current to zero wall thickness. Monte Carlo calculations by Rogers and Bielajew (1990 Phys. Med. Biol. 35 1065-78) provided evidence, mostly for chambers of cylindrical and spherical geometry, of appreciable deviations between the calculated values of Kwall and those obtained by the traditional extrapolation procedure. In the present work an experimental method other than the traditional extrapolation procedure was used to determine the Kwall factor. In this method the dependence of the ionization current in a cylindrical chamber was analysed as a function of an effective wall thickness in place of the physical (radial) wall thickness traditionally considered in this type of measurement. To this end the chamber wall was ideally divided into distinct regions and for each region an effective thickness to which the chamber current correlates was determined. A Monte Carlo calculation of attenuation and scatter effects in the different regions of the chamber wall was also made to compare calculation to measurement results. The Kwall values experimentally determined in this work agree within 0.2% with the Monte Carlo calculation. The agreement between these independent methods and the appreciable deviation (up to about 1%) between the results of both these methods and those obtained by the traditional extrapolation procedure support the conclusion that the two independent methods providing comparable results are correct and the traditional extrapolation procedure is likely to be wrong. The numerical results of the present study refer to a cylindrical cavity chamber like that adopted as the Italian national air-kerma standard at INMRI-ENEA (Italy). The method used in this study applies, however, to any other chamber of the same type. (author)

  7. Interlaboratory comparisons in kerma in the air measures and absorbed dose in water using {sup 6}0Co beams in radiotherapy; Comparacoes interlaboratoriais nas medidas de kerma no ar e dose absorvida na agua utilizando feixes de {sup 60}Co em radioterapia

    Energy Technology Data Exchange (ETDEWEB)

    Rosado, Paulo Henrique Goncalves; Silva, Cosme Norival Mello da, E-mail: phrosado@ird.gov.br [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2013-07-01

    In order to ensure that the measures of a quantity have high reliability and traceability interlaboratory comparisons are performed. The LNMRI has participated in several these interlaboratory comparisons. In the period 2000-2013 the LNMRI participated in 5 interlaboratory comparisons for measurement of kerma coefficients in the air and absorbed dose coefficients in the water. The results of interlaboratory comparisons indicate that the measures taken are appropriate to the LNMRI regarding the accuracy and precision measuring of these quantities.

  8. KERMA ratios in pediatric CT dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Huda, Walter [Medical University of South Carolina (MUSC), Department of Radiology and Radiological Science, Charleston, SC (United States); Ogden, Kent M.; Lavallee, Robert L.; Roskopf, Marsha L.; Scalzetti, Ernest M. [SUNY Upstate Medical University, Department of Radiology, Syracuse, NY (United States)

    2012-05-15

    Patient organ doses may be estimated from CTDI values. More accurate estimates may be obtained by measuring KERMA (Kinetic Energy Released in Matter) in anthropomorphic phantoms and referencing these values to free-in-air X-ray intensity. To measure KERMA ratios (R{sub K}) in pediatric phantoms at CT. CT scans produce an air KERMA K in a phantom and an air KERMA K{sub CT} at isocenter. KERMA ratios (R{sub K}) are defined as (K/K{sub CT}), measured using TLD chips in phantoms representing newborns to 10-year-olds. R{sub K} in the newborn is approximately constant. For the other phantoms, there is a peak R{sub K} value in the neck. The median R{sub K} values for the GE scanner at 120 kV were 0.92, 0.83, 0.77 and 0.76 for newborns, 1-year-olds, 5-year-olds and 10-year-olds, respectively. Organ R{sub K} values were 0.91 {+-} 0.04, 0.84 {+-} 0.07, 0.74 {+-} 0.09 and 0.72 {+-} 0.10 in newborns, 1-year-olds, 5-year-olds and 10-year-olds, respectively. At 120 kV, a Siemens Sensation 16 scanner had R{sub K} values 5% higher than those of the GE LightSpeed Ultra. KERMA ratios may be combined with air KERMA measurements at the isocenter to estimate organ doses in pediatric CT patients. (orig.)

  9. Reference dosimetry at the Australian Synchrotron's imaging and medical beamline using free-air ionization chamber measurements and theoretical predictions of air kerma rate and half value layer

    Energy Technology Data Exchange (ETDEWEB)

    Crosbie, Jeffrey C.; Rogers, Peter A. W. [Department of Obstetrics and Gynaecology, University of Melbourne, The Royal Women' s Hospital, Parkville, Victoria 3052 (Australia); Stevenson, Andrew W. [CSIRO Materials Science and Engineering, Clayton, Victoria 3169 (Australia); Hall, Christopher J. [Imaging and Medical Beamline, Australian Synchrotron, Clayton, Victoria 3168 (Australia); Lye, Jessica E. [Australian Radiation Protection and Nuclear Safety Agency, Yallambie, Victoria 3085 (Australia); Nordstroem, Terese [KTH Royal Institute of Technology, Stockholm SE-100 44 (Sweden); Midgley, Stewart M. [School of Physics, Monash University, Clayton, Victoria 3800 (Australia); Lewis, Robert A. [Department of Medical Imaging and Radiation Sciences, Monash University, Clayton, Victoria 3800 (Australia)

    2013-06-15

    Purpose: Novel, preclinical radiotherapy modalities are being developed at synchrotrons around the world, most notably stereotactic synchrotron radiation therapy and microbeam radiotherapy at the European Synchrotron Radiation Facility in Grenoble, France. The imaging and medical beamline (IMBL) at the Australian Synchrotron has recently become available for preclinical radiotherapy and imaging research with clinical trials, a distinct possibility in the coming years. The aim of this present study was to accurately characterize the synchrotron-generated x-ray beam for the purposes of air kerma-based absolute dosimetry. Methods: The authors used a theoretical model of the energy spectrum from the wiggler source and validated this model by comparing the transmission through copper absorbers (0.1-3.0 mm) against real measurements conducted at the beamline. The authors used a low energy free air ionization chamber (LEFAC) from the Australian Radiation Protection and Nuclear Safety Agency and a commercially available free air chamber (ADC-105) for the measurements. The dimensions of these two chambers are different from one another requiring careful consideration of correction factors. Results: Measured and calculated half value layer (HVL) and air kerma rates differed by less than 3% for the LEFAC when the ion chamber readings were corrected for electron energy loss and ion recombination. The agreement between measured and predicted air kerma rates was less satisfactory for the ADC-105 chamber, however. The LEFAC and ADC measurements produced a first half value layer of 0.405 {+-} 0.015 and 0.412 {+-} 0.016 mm Cu, respectively, compared to the theoretical prediction of 0.427 {+-} 0.012 mm Cu. The theoretical model based upon a spectrum calculator derived a mean beam energy of 61.4 keV with a first half value layer of approximately 30 mm in water. Conclusions: The authors showed in this study their ability to verify the predicted air kerma rate and x-ray attenuation curve on the IMBL using a simple experimental method, namely, HVL measurements. The HVL measurements strongly supports the x-ray beam spectrum, which in turn has a profound effect on x-ray dosimetry.

  10. Control letters and uncertainties of the kerma patterns in air, dose absorbed in water and dose absorbed in air of the LSCD

    International Nuclear Information System (INIS)

    With the purpose of characterizing the component of uncertainty of long term of the patron ionization chambers of the LSCD, for the magnitudes: speed of kerma in air Κα·, dose speed absorbed in water Dα·, and speed absorbed dose in air Dα·, it use the technique of letters of control l-MR/S. This statistical technique it estimates the component of uncertainty of short term by means of the deviation standard inside groups σω and that of long term by means of the standard deviation among groups σβ, being this it finishes an estimator of the stability of the patterns.The letters of control l-MR/S it construct for: i) Κα·, in radiation field of 60Co for patterns: primary CC01 series 131, secondary NE 2611 series 176, secondary PTW TN30031 series 578 and Third PTW W30001 series 365. ii) Dα),en radiation field of 60Co for patterns: primary CC01 series 131, Secondary PTW TN30031 series 578 and tertiary PTW W30001 series 365. iii) I-MR/S with extrapolation chamber PTW primary pattern, measurement realizes in secondary patron fields of 90Sr-90Y. The expanded uncertainty U it is calculated of agreement with the Guide of the ISO/BIPM being observed the following thing: a. In some the cases σβ, is the component of the U that more contributed to this. Therefore, it is necessary to settle down technical of sampling in those mensurations that allow to reduce the value of σβ. For example with sizes of subgroup η∼ 30 data, or with a number of subgroups κ≥. That which is achieved automating the mensuration processes. b.The component of the temperature is also one of those that but they contribute to the U, of there the necessity of: to recover the tracking for this magnitude of it influences and to increase the precision in the determinations of the temperature to diminish their influence in the U. c. The percentage difference of the magnitudes dosemeters carried out by it patterns are consistent with U certain. However, it is necessary to diminish the uncertainty in the physical factors different to κτ and σβ for the one case of the primary patterns; because these they should be those of smaller value of U. d. In the case of the secondary patterns and tertiary for the realization of theκα· is necessary to determine the corrections explicitly for recombination and polarization; and to analyze their contribution in the U. e. It is necessary to recover the tracking for the mensurations of the humidity. f. It is recommended to continue the control mensurations for each pattern, taking its the least a measure every fifteen days, that it corresponds at two measured for month and 24 at the year. g. The operation of the air conditioned perturb the measurement for such as it recommends not to use it, and alone to leave in balance the chamber with the air of the engine room. (Author)

  11. Poster — Thur Eve — 24: Commissioning and preliminary measurements using an Attix-style free air ionization chamber for air kerma measurements on the BioMedical Imaging and Therapy beamlines at the Canadian Light Source

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, D [Department of Oncology, University of Alberta, Edmonton, AB (Canada); McEwen, M; Shen, H [Ionizing Radiation Standards, National Research Council of Canada, Ottawa, ON (Canada); Siegbahn, EA [Department of Medical Physics, Stockholm University, Stockholm (Sweden); Fallone, BG; Warkentin, B [Department of Oncology, University of Alberta, Edmonton, AB (Canada); Department of Medical Physics, Cross Cancer Institute, Edmonton, AB (Canada)

    2014-08-15

    Synchrotron facilities, including the Canadian Light Source (CLS), provide opportunities for the development of novel imaging and therapy applications. A vital step progressing these applications toward clinical trials is the availability of accurate dosimetry. In this study, a refurbished Attix-style (cylindrical) free air chamber (FAC) is tested and used for preliminary air kerma measurements on the two BioMedical Imaging and Therapy (BMIT) beamlines at the CLS. The FAC consists of a telescoping chamber that relies on a difference measurement of collected charge in expanded and collapsed configurations. At the National Research Council's X-ray facility, a Victoreen Model 480 FAC was benchmarked against two primary standard FACs. The results indicated an absolute accuracy at the 0.5% level for energies between 60 and 150 kVp. A series of measurements were conducted on the small, non-uniform X-ray beams of the 05B1-1 (?8 – 100 keV) and 05ID-2 (?20 – 200 keV) beamlines for a variety of energies, filtrations and beam sizes. For the 05B1-1 beam with 1.1 mm of Cu filtration, recombination corrections of less than 5 % could only be achieved for field sizes no greater than 0.5 mm × 0.6 mm (corresponding to an air kerma rate of ? 57 Gy/min). Ionic recombination thus presents a significant challenge to obtaining accurate air kerma rate measurements using this FAC in these high intensity beams. Future work includes measurements using a smaller aperture to sample a smaller and thus more uniform beam area, as well as experimental and Monte Carlo-based investigation of correction factors.

  12. Poster — Thur Eve — 24: Commissioning and preliminary measurements using an Attix-style free air ionization chamber for air kerma measurements on the BioMedical Imaging and Therapy beamlines at the Canadian Light Source

    International Nuclear Information System (INIS)

    Synchrotron facilities, including the Canadian Light Source (CLS), provide opportunities for the development of novel imaging and therapy applications. A vital step progressing these applications toward clinical trials is the availability of accurate dosimetry. In this study, a refurbished Attix-style (cylindrical) free air chamber (FAC) is tested and used for preliminary air kerma measurements on the two BioMedical Imaging and Therapy (BMIT) beamlines at the CLS. The FAC consists of a telescoping chamber that relies on a difference measurement of collected charge in expanded and collapsed configurations. At the National Research Council's X-ray facility, a Victoreen Model 480 FAC was benchmarked against two primary standard FACs. The results indicated an absolute accuracy at the 0.5% level for energies between 60 and 150 kVp. A series of measurements were conducted on the small, non-uniform X-ray beams of the 05B1-1 (?8 – 100 keV) and 05ID-2 (?20 – 200 keV) beamlines for a variety of energies, filtrations and beam sizes. For the 05B1-1 beam with 1.1 mm of Cu filtration, recombination corrections of less than 5 % could only be achieved for field sizes no greater than 0.5 mm × 0.6 mm (corresponding to an air kerma rate of ? 57 Gy/min). Ionic recombination thus presents a significant challenge to obtaining accurate air kerma rate measurements using this FAC in these high intensity beams. Future work includes measurements using a smaller aperture to sample a smaller and thus more uniform beam area, as well as experimental and Monte Carlo-based investigation of correction factors

  13. Conversion coefficients from air kerma to personal dose equivalent H{sub p}(3) fir eye-lens dosimetry; Coeficients de conversion du kerma dans l'air a l'equivalent de dose individuel H{sub p}(3) pour la dosimetrie du cristalin

    Energy Technology Data Exchange (ETDEWEB)

    Daures, J.; Gouriou, J.; Bordy, J.M

    2009-07-01

    This work has been performed within the frame of the European Union ORAMED project (Optimization of Radiation protection for Medical staff). The main goal of the project is to improve standards of protection for medical staff for procedure resulting in potentially high exposures and to develop methodologies for better assessing and for reducing exposures to medical staff. The Work Package WP2 is involved in the development of practical eye lens dosimetry in interventional radiology. This study is complementary of the part of the ENEA report concerning the calculations with the MCNP code of the conversion factors related to the operational quantity H{sub p}(3). A set of energy and angular dependent conversion coefficients H{sub p}(3)/K{sub air} in the new proposed square cylindrical phantom of ICRU tissue, have been calculated with the Monte-Carlo code PENELOPE. The H{sub p}(3) values have been determined in terms of absorbed dose, according to the definition of this quantity, and also with the kerma approximation as formerly reported in ICRU reports. At low photon energy, up to 1 MeV, the two sets of conversion coefficients are consistent. Nevertheless, the differences increase at higher energy. This is mainly due to the lack of electronic equilibrium, especially for small angle incidences. The values of the conversion coefficients obtained with the code MCNP published by ENEA, agree with the kerma approximation calculations with PENELOPE. They are coherent with previous calculations in phantoms different in shape. But above 1 MeV, differences between conversion coefficient values calculated with the absorbed dose and with kerma approximation are significantly increasing, especially at low incidence angles. At those energies the electron transport has to be simulated. (author)

  14. Neutron kerma factors, and water equivalence of some tissue substitutes

    International Nuclear Information System (INIS)

    The kerma factors and kerma relative to air and water of 24 compounds used as tissue substitutes were calculated for neutron energy from 2.53 x 10-8 up to 29 MeV. The kerma ratio of the tissue substitutes relative to air and water were calculated by the ratio of kerma factors of the tissue substitute to air and water respectively. The water equivalence of the selected tissue substitutes was observed above neutron energies 100 eV. Kerma ratio relative to the air for Poly-vinylidene fluoride and Teflon are found to be nearest to unity in very low energy (up to 1 eV) and above 63 eV respectively. It was found that the natural rubber as a water equivalent tissue substitute compound. The results of the kerma factors in our investigation shows a very good agreement with those published in ICRU-44. We found that at higher neutron energies, the kerma factors and kerma ratios of the selected tissue substitute compounds are approximately same, but differences are large for energies below 100 eV. (Author)

  15. Estudo comparativo da qualidade da imagem e do kerma, de entrada e de saída, em simulador de tórax utilizando sistemas analógico e digitalizado CR de aquisição de imagens / Comparative study of image quality and entrance and exit air kerma measurements on chest phantom utilizing analog and CR digital imaging systems

    Scientific Electronic Library Online (English)

    Renata Matos da, Luz; Gabriela, Hoff.

    2010-02-01

    Full Text Available OBJETIVO: O processo de migração de sistemas analógicos para digitalizados, para aplicações diagnósticas, requer cuidados específicos, a fim de manter a qualidade das imagens e minimizar a dose no paciente. Este trabalho tem como objetivo analisar e comparar a qualidade da imagem e o kerma num simul [...] ador não antropomórfico de tórax gerados por sistemas analógicos e digitalizados CR. MATERIAIS E MÉTODOS: Foram analisados a qualidade da imagem e o kerma, de entrada e saída, no simulador para dois equipamentos de raios X diferentes (Siemens e Emic), com diferentes sistemas de retificação de onda (12 pulsos e alta frequência). Ambos os sistemas (analógico e digitalizado) estavam sendo utilizados no mesmo local. Foram geradas imagens em filme e em image plates. RESULTADOS: Foi observado aumento na tensão e/ou na carga transportada pelo tubo de raios X quando houve a migração para o sistema CR, para manutenção das características diagnósticas da imagem. Isto resultou em aumento de kerma coletado. CONCLUSÃO: As maiores diferenças determinadas (aumento de dose e redução da qualidade da imagem) foram observadas no equipamento com retificação de onda de 12 pulsos e transdutor de imagem CR (image plates). Abstract in english OBJECTIVE: The process of migration from analog to digital imaging system requires specific attention to preserve images quality and minimizing the dose to the patients. The present study was aimed at analyzing and comparing images quality and entrance and exist air kerma measurements in a non-anthr [...] opomorphic chest phantom with analog and CR digital imaging systems. MATERIALS AND METHODS: Two different X-ray units (Siemens and Emic) with different wave rectification systems (12-pulse and high-frequency) were utilized in a single institution along the process of migration from analog to CR digital imaging system. Images were acquired on films and image plates. RESULTS: An increase on the X-ray tube peak voltage and/or load was observed in the migration from analog to CR digital system to preserve the diagnostic quality of the image. As a result, an increase in the air kerma rate was observed. CONCLUSION: The greatest differences (increase in dose and decrease in image quality) were observed with the 12-pulse wave rectification system with the CR image transducer (imaging plates).

  16. Estudo comparativo da qualidade da imagem e do kerma, de entrada e de saída, em simulador de tórax utilizando sistemas analógico e digitalizado CR de aquisição de imagens Comparative study of image quality and entrance and exit air kerma measurements on chest phantom utilizing analog and CR digital imaging systems

    Directory of Open Access Journals (Sweden)

    Renata Matos da Luz

    2010-02-01

    Full Text Available OBJETIVO: O processo de migração de sistemas analógicos para digitalizados, para aplicações diagnósticas, requer cuidados específicos, a fim de manter a qualidade das imagens e minimizar a dose no paciente. Este trabalho tem como objetivo analisar e comparar a qualidade da imagem e o kerma num simulador não antropomórfico de tórax gerados por sistemas analógicos e digitalizados CR. MATERIAIS E MÉTODOS: Foram analisados a qualidade da imagem e o kerma, de entrada e saída, no simulador para dois equipamentos de raios X diferentes (Siemens e Emic, com diferentes sistemas de retificação de onda (12 pulsos e alta frequência. Ambos os sistemas (analógico e digitalizado estavam sendo utilizados no mesmo local. Foram geradas imagens em filme e em image plates. RESULTADOS: Foi observado aumento na tensão e/ou na carga transportada pelo tubo de raios X quando houve a migração para o sistema CR, para manutenção das características diagnósticas da imagem. Isto resultou em aumento de kerma coletado. CONCLUSÃO: As maiores diferenças determinadas (aumento de dose e redução da qualidade da imagem foram observadas no equipamento com retificação de onda de 12 pulsos e transdutor de imagem CR (image plates.OBJECTIVE: The process of migration from analog to digital imaging system requires specific attention to preserve images quality and minimizing the dose to the patients. The present study was aimed at analyzing and comparing images quality and entrance and exist air kerma measurements in a non-anthropomorphic chest phantom with analog and CR digital imaging systems. MATERIALS AND METHODS: Two different X-ray units (Siemens and Emic with different wave rectification systems (12-pulse and high-frequency were utilized in a single institution along the process of migration from analog to CR digital imaging system. Images were acquired on films and image plates. RESULTS: An increase on the X-ray tube peak voltage and/or load was observed in the migration from analog to CR digital system to preserve the diagnostic quality of the image. As a result, an increase in the air kerma rate was observed. CONCLUSION: The greatest differences (increase in dose and decrease in image quality were observed with the 12-pulse wave rectification system with the CR image transducer (imaging plates.

  17. Comparison of the air kerma standards for 137Cs and 60Co gamma-ray beams between the IAEA and the NIST

    Science.gov (United States)

    Minniti, Ronaldo; Czap, Ladislav

    2011-01-01

    A comparison of the air kerma standards for 137Cs and 60Co gamma-ray beams was performed between the NIST and the IAEA. Two reference class ionization chambers owned by the IAEA were used as part of this comparison and were calibrated at each facility. The calibration coefficients, NK, were determined for both chambers and in both gamma-ray beams. The measurements were performed at the IAEA and NIST facilities starting in the fall of 2009 and were completed in 2010. The comparison ratio of the calibration coefficients for each chamber, NK,IAEA/NK,NIST, between the IAEA and NIST was 0.999 and 0.997 for the 137Cs and 60Co gamma-ray beams respectively. The relative standard uncertainty for each of these ratios is 0.5%. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by SIM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  18. Implementation of the method air-kerma product area in KAP camera calibration with reference qualities of X-ray series at the SSDL RQR of Mexico

    International Nuclear Information System (INIS)

    The X-Ray machines, at a reference laboratory for the instrument calibration in diagnostic radiology, should compliance with the ISO requirements. Sometimes there is not available as much laboratories as needed in Latin American countries. So this project shows the KAP ionization chamber implementation method using the TRS-457 radiation quality from the IAEA at the SSDL of Mexico. The KAP instruments calibration method consists in doing a substitution comparison using a standard reference with traceability to a primary laboratory and a transmission-monitoring chamber that measures the number of photons of the X-ray primary beam. A KAP chamber calibration requires a special array that consists in collocating the chamber in two different positions of its calibration process. Then, with air kerma-area product coefficient together with a corrected electrometer measure at referential conditions, the patient dosimetry magnitudes are calculated. The dosimetry necessity at hospitals always will be in function of possessing a highly reliable calibration coefficient chamber for making these measures. That dosimetry results will help in reducing the total or partial irradiation emitted to the human body of the patient. This is how stochastic risks will be lessened due to diagnostic studies. The purpose of this project is to have a synergy with calibration for making known that the SSDL of Mexico has the technical capacity to act as a link between primary standard dosimetry laboratories and the ionizing radiation equipment users who require that their KAP chamber have traceability from the primary standard to the user. (author)

  19. Air kerma to personal dose equivalent conversion factors for ICRU and ISO recommended slab phantoms for photons from 20 keV to 1 MeV

    International Nuclear Information System (INIS)

    The present report summarizes the studies carried out at ENEA-AMB-PRO-IRP (Institute for Radiation Protection) that were addressed to the determination of air kerma to personal dose equivalent conversion coefficients for two practical phantoms as proposed by ICRU (International Commission for Radiation Units and Measurements) and by ISO (International Standard Organization) for photon personal dosimeters' calibration procedure. The analyses, developed using the MCNP Monte Carlo code, were mainly aimed at establishing which of the two proposed phantoms better approximates the ICRU theoretical one. Furthermore a complete tabulation of the conversion coefficients is supplied for monoenergetic photon beams from 20 keV to 1 MeV as well as for the two ISO X-ray reference series Wide Spectrum and Narrow Spectrum. The study has been performed in the framework of the CEC Contract F13P-CT92-0064 'The Measurement of the Spectral and Angular Distribution of External Radiations in Workplace and Implications for Personal Dosimetry

  20. Modelling the contribution of individual radionuclides to the total gamma air kerma rate for the sediments of the Ribble Estuary, NW England.

    Science.gov (United States)

    Brown, J E; McDonald, P; Williams, M; Parker, A; Rae, J E

    1999-12-01

    The aim of this study was to test the performance of a published dose-rate model, investigate the contribution of individual radionuclides to the total gamma air kerma rate (GAKR) and derive external doses to man in the Ribble Estuary, NW England. GAKRs were measured and sediment cores were collected in order to determine radionuclide specific activities with depth. The latter values were used as input data for the external dose-rate model. The model has a slight tendency to over-predict the GAKR, but, on average, the model predictions fall within +/-26% of the measured value. Improvements, in the present case, might be made by accounting for core shortening and variations in soil density in the input data. The model predicted that, for exposed intertidal mud sites, a range of GAKRs between 0.011 and 0.022 microGy h(-1) was attributable to Springfields discharges alone. The contribution due to 234mPa and 234Th ranged between 20 and 60%. An excess GAKR (GAKR arising from anthropogenic emissions alone) of 0.139-0.150 microGy h(-1), used in conjunction with relevant habit-survey data (for a potential critical group) and conversion factors, yielded a dose to man of 0.029-0.031 mSv year(-1). PMID:10616780

  1. Modelling the contribution of individual radionuclides to the total gamma air kerma rate for the sediments of the Ribble Estuary, NW England

    International Nuclear Information System (INIS)

    The aim of this study was to test the performance of a published dose-rate model, investigate the contribution of individual radionuclides to the total gamma air kerma rate (GAKR) and derive external doses to man in the Ribble Estuary, NW England. GAKRs were measured and sediment cores were collected in order to determine radionuclide specific activities with depth. The latter values were used as input data for the external dose-rate model. The model has a slight tendency to over-predict the GAKR, but, on average, the model predictions fall within ±26% of the measured value. Improvements, in the present case, might be made by accounting for core shortening and variations in soil density in the input data. The model predicted that, for exposed intertidal mud sites, a range of GAKRs between 0.011 and 0.022 ?Gy h-1 was attributable to Springfields discharges alone. The contribution due to 234mPa and 234Th ranged between 20 and 60%. An excess GAKR (GAKR arising from anthropogenic emissions alone) of 0.139-0.150 ?Gy ?Gy h-1, used in conjunction with relevant habit-survey data (for a potential critical group) and conversion factors, yielded a dose to man of 0.029-0.031 mSv year-1. (author)

  2. Comparison between absorbed dose to water standards established by water calorimetry at the LNE-LNHB and by application of international air-kerma based protocols for kilovoltage medium energy x-rays

    International Nuclear Information System (INIS)

    Nowadays, the absorbed dose to water for kilovoltage x-ray beams is determined from standards in terms of air-kerma by application of international dosimetry protocols. New standards in terms of absorbed dose to water has just been established for these beams at the LNE-LNHB, using water calorimetry, at a depth of 2 cm in water in accordance with protocols. The aim of this study is to compare these new standards in terms of absorbed dose to water, to the dose values calculated from the application of four international protocols based on air-kerma standards (IAEA TRS-277, AAPM TG-61, IPEMB and NCS-10). The acceleration potentials of the six beams studied are between 80 and 300 kV with half-value layers between 3.01 mm of aluminum and 3.40 mm of copper. A difference between the two methods smaller than 2.1% was reported. The standard uncertainty of water calorimetry being below 0.8%, and the one associated with the values from protocols being around 2.5%, the results are in good agreement. The calibration coefficients of some ionization chambers in terms of absorbed dose to water, established by application of calorimetry and air-kerma based dosimetry protocols, were also compared. The best agreement with the calibration coefficients established by water calorimetry was found for those established with the AAPM TG-61 protocol. (paper)

  3. Air quality complex index estimation of air pollution situations

    International Nuclear Information System (INIS)

    To improve the regional system for assessment and management of the ambient air quality in the North-East Estonian region of oil shale mining and processing, as well as natural areas, the corresponding Air Quality Complex Index (AQI) has been elaborated. This method enables to generalize a large number of measured numerical values of concentrations of pollutants in case of multicomponential pollution fields and makes the results more easily understandable. The AQI is suitable for the real-time monitoring as well as for prediction of air quality values and pollution situations by calculated data. (author)

  4. Microionization chamber air-kerma calibration coefficients as a function of photon energy for x-ray spectra in the range of 20–250 kVp relative to 60Co

    International Nuclear Information System (INIS)

    Purpose: To investigate the applicability of a wide range of microionization chambers for reference dosimetry measurements in low- and medium-energy x-ray beams. Methods: Measurements were performed with six cylindrical microchamber models, as well as one scanning chamber and two Farmer-type chambers for comparison purposes. Air-kerma calibration coefficients were determined at the University of Wisconsin Accredited Dosimetry Calibration Laboratory for each chamber for a range of low- and medium-energy x-ray beams (20–250 kVp), with effective energies ranging from 11.5 keV to 145 keV, and a 60Co beam. A low-Z proof-of-concept microchamber was developed and calibrated with and without a high-Z silver epoxy on the collecting electrode. Results: All chambers composed of low-Z materials (Z? 13), including the Farmer-type chambers, the scanning chamber, and the PTW TN31014 and the proof-of-concept microchambers, exhibited air-kerma calibration coefficients with little dependence on the quality of the beam. These chambers typically exhibited variations in calibration coefficients of less than 3% with the beam quality, for medium energy beams. However, variations in air-kerma calibration coefficients of greater than 50% were measured over the range of medium-energy x-ray beams for each of the microchambers containing high-Z collecting electrodes (Z > 13). For these high-Z chambers, which include the Exradin A14SL and A16 chambers, the PTW TN31006 chamber, the IBA CC01 chamber, and the proof-of-concept chamber containing silver, the average variation in air-kerma calibration coefficients between any two calibration beams was nearly 25% over the entire range of beam qualities investigated. Conclusions: Due to the strong energy dependence observed with microchambers containing high-Z components, these chambers may not be suitable dosimeters for kilovoltage x-ray applications, as they do not meet the TG-61 requirements. It is recommended that only microchambers containing low-Z materials (Z? 13) be considered for air-kerma calibrations for reference dosimetry in low- and medium-energy x-ray beams.

  5. The calculation of wall and non-uniformity correction factors for the BIPM air-kerma standard for 60Co using the Monte Carlo code PENELOPE

    International Nuclear Information System (INIS)

    Traditionally, the correction factor kwall for attenuation and scatter in the walls of cavity ionization chamber primary standards has been evaluated experimentally using an extrapolation method. During the past decade, there have been a number of Monte Carlo calculations of kwall indicating that for certain ionization chamber types the extrapolation method may not be valid. In particular, values for kwall have been proposed that, if adopted by each laboratory concerned, would have a significant effect on the results of international comparisons of air-kerma primary standards. The calculations have also proposed new values for the axial component kan of the point-source uniformity correction. Central to the results of international comparisons is the BIPM air-kerma standard. Unlike most others, the BIPM standard is of the parallel-plate design for which the extrapolation method for evaluating kwall should be valid. The value in use at present is kwall=1.0026 (standard uncertainty 0.0008). Rogers and Treurniet calculated the value kwall=1.0014 for the BIPM standard, which is in moderate agreement with the value in use (no overall uncertainty was given). However, they also calculated kan=1.0024 (statistical uncertainty 0.0003) which is very different from the value kan=0.9964 (0.0007) in use at present for the BIPM standard. A new 60Co facility has recently been installed at the BIPM and the opportunity was taken to re-evaluate the correction factors for the BIPM standard in this new beam. Given that almost all of the Monte Carlo work to date has used the EGS Monte Carlo code, it was decided to use the code PENELOPE. The new source, container, head and collimating jaws were simulated in detail with more that fifty components being modelled, as shown. This model was used to create a phase-space file in the plane 90 cm from the source. The normalized distribution of photon number with energy is shown, where the various sources of scattered photons are identified. This phase-space file was used to calculate kwall for the BIPM standard using the technique of photon regeneration. At the point of each photon interaction in the chamber wall, a new photon is generated with the same energy and direction as the incoming photon. The deposition of energy in the air cavity by regenerated photons effectively corrects for attenuation in the wall. At the same time, any outgoing scattered photon is tagged so that a correction for the energy deposition due to scattered photons may be evaluated. The result of these calculations is kwall=1.0017 (statistical uncertainty 0.0001), which is in good agreement with previous results. The overall uncertainties remain to be evaluated. For the calculation of kan, a modified technique was used which makes use of the full phase-space information rather than assuming, as is usual, that the beam is well approximated by a point source. When using the same model for the BIPM standard as used previously, the result kan=1.0032 (statistical uncertainty 0.0005) agrees reasonably well with previous results (the small difference may be due to the use of a point source rather than the realistic angular distribution). However, there is evidence that these new values are an artefact of the method and model and that the true non-uniformity correction is much closer to unity. Before implementing any new kan value for the BIPM standard, a more detailed study will be undertaken to explain the large difference between the new and existing values

  6. Control letters and uncertainties of the kerma patterns in air, dose absorbed in water and dose absorbed in air of the LSCD; Cartas de control e incertidumbres de los patrones de kerma en aire, dosis absorbida en agua y dosis absorbida en aire del LSCD

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez R, M.T.; Tovar M, V.M.; Cejudo A, J. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    2005-12-15

    With the purpose of characterizing the component of uncertainty of long term of the patron ionization chambers of the LSCD, for the magnitudes: speed of kerma in air {kappa}{sub {alpha}}{sub {center_dot}}, dose speed absorbed in water D{alpha}{sub {center_dot}}, and speed absorbed dose in air D{alpha}{sub {center_dot}}, it use the technique of letters of control l-MR/S. This statistical technique it estimates the component of uncertainty of short term by means of the deviation standard inside groups {sigma}{sub {omega}} and that of long term by means of the standard deviation among groups {sigma}{sub {beta}}, being this it finishes an estimator of the stability of the patterns.The letters of control l-MR/S it construct for: i) {kappa}{sub {alpha}}{sub {center_dot}}, in radiation field of {sup 60}Co for patterns: primary CC01 series 131, secondary NE 2611 series 176, secondary PTW TN30031 series 578 and Third PTW W30001 series 365. ii) D{alpha}),en radiation field of {sup 60}Co for patterns: primary CC01 series 131, Secondary PTW TN30031 series 578 and tertiary PTW W30001 series 365. iii) I-MR/S with extrapolation chamber PTW primary pattern, measurement realizes in secondary patron fields of {sup 90}Sr-{sup 90}Y. The expanded uncertainty U it is calculated of agreement with the Guide of the ISO/BIPM being observed the following thing: a. In some the cases {sigma}{sub {beta}}, is the component of the U that more contributed to this. Therefore, it is necessary to settle down technical of sampling in those mensurations that allow to reduce the value of {sigma}{sub {beta}}. For example with sizes of subgroup {eta}{sub {approx}} 30 data, or with a number of subgroups {kappa}{sub {>=}}. That which is achieved automating the mensuration processes. b.The component of the temperature is also one of those that but they contribute to the U, of there the necessity of: to recover the tracking for this magnitude of it influences and to increase the precision in the determinations of the temperature to diminish their influence in the U. c. The percentage difference of the magnitudes dosemeters carried out by it patterns are consistent with U certain. However, it is necessary to diminish the uncertainty in the physical factors different to {kappa}{sub {tau}} and {sigma}{sub {beta}} for the one case of the primary patterns; because these they should be those of smaller value of U. d. In the case of the secondary patterns and tertiary for the realization of the{kappa}{sub {alpha}}{sub {center_dot}} is necessary to determine the corrections explicitly for recombination and polarization; and to analyze their contribution in the U. e. It is necessary to recover the tracking for the mensurations of the humidity. f. It is recommended to continue the control mensurations for each pattern, taking it{sup s} the least a measure every fifteen days, that it corresponds at two measured for month and 24 at the year. g. The operation of the air conditioned perturb the measurement for such as it recommends not to use it, and alone to leave in balance the chamber with the air of the engine room. (Author)

  7. Neutron kerma factors and water equivalence of some tissue substitutes.

    Science.gov (United States)

    Singh, V P; Badiger, N M; Vega-Carrillo, Hector Rene

    2015-09-01

    The Kerma factors and Kerma relative to the air and water of 24 compounds that are used as tissue substitutes were calculated for neutron energies ranging from 2.53×10(-8) to 29 MeV. The Kerma ratios of the tissue substitutes relative to air and water were calculated. The water equivalence of the selected tissue substitutes was observed above neutron energies of 100 eV. The Kerma ratio relative to the air for poly-vinylidene fluoride and Teflon were nearest to unity at very low energy (up to 1 eV) and above 63 eV, respectively. It was found that the natural rubber was a water-equivalent tissue substitute compound. The results of the Kerma factors in our investigation show good agreement with those published in ICRU-44. We found that at higher neutron energies, the Kerma factors and Kerma ratios of the selected tissue substitute compounds were approximately the same, but though the differences were large for energies below 100 eV. PMID:26073270

  8. CDC WONDER: Daily Air Temperatures and Heat Index

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Daily Air Temperature and Heat Index data available on CDC WONDER are county-level daily average air temperatures and heat index measures spanning the years...

  9. Final report on APMP.RI(I)-K1: APMP/TCRI key comparison report of measurement of air kerma for 60Co gamma-rays

    International Nuclear Information System (INIS)

    The APMP.RI(I)-K1 key comparison of the measurement standards of air kerma for 60Co gamma-rays was undertaken by the APMP/TCRI Dosimetry Working Group between 2004 and 2006, coordinated by the Korean Research Institute of Standards and Science (KRISS). In total, 10 institutes took part in the comparison, among which 7 were APMP member laboratories. Three Farmer-type commercial cavity chambers were used as transfer chambers and circulated among the participants. All the participants carried out their measurements according to the guidelines for the comparison established by the KRISS with the cooperation of the ARPANSA. For each transfer chamber, an NMI calibration coefficient was obtained and a ratio derived by dividing by the average result from the linking laboratories, ARPANSA and NMIJ. The APMP comparison reference value for each chamber was calculated as the mean of the NMI-determined calibration coefficients divided by the average result from the linking laboratories. The results showed that the maximum difference between the APMP linked ratio of a participating NMI and the APMP reference value was 1.76 %. The measured ratios of the calibration coefficient NMI, BIPM R between the participating NMI and the BIPM via the link laboratories for the transfer chambers were obtained. The maximum expanded uncertainty of NMI, BIPM R for any participating laboratory was 2.0 %. The degree of equivalence of each participating laboratory with respect to the key comparison reference value was also evaluated. The expanded uncertainty of the difference between the results ranged from 0.5 % to 1.2 %. The pair-wise degree of equivalence between each pair of laboratories was also obtained and the largest difference of the expanded uncertainty of the difference for any pair-wise degree of equivalence was within the expanded uncertainty of the measurement for the pair of laboratories. (authors)

  10. SOILRAD. A computer program to calculate air kerma, ambient dose rate and effective dose rate due to photons emitted by radionuclides distributed in soil on the soil-air surface

    International Nuclear Information System (INIS)

    In several research projects on environmental radiation there is a need for an automated system to calculate, for instance, the kerma in air or ambient dose rate that results from photons emitted by radionuclides in soil or on the soil surface. Some applications are migration of fallout radionuclides in soil, calculation of the shielding effect of soil due to landfill and the calculation of dose rate due to the naturally occurring radionuclides in soil. In the framework of an investigation aimed at determining the natural radiation background using the National Radioactivity Monitoring network (NRM), a computer application was developed for this purpose. In this report the underlying calculation method is described. An already existing method was adapted and expanded. Besides a description of this method, the structure of the SOILRAD program is illustrated and instructions for use are given. Comparison of the first results to data published elsewhere confirms the usefulness of the program. 13 figs., 4 tabs., 20 refs., 3 appendices

  11. Key comparison BIPM.RI(I)-K2 of the air-kerma standards of the ENEA-INMRI, Italy and the BIPM in low-energy x-rays

    International Nuclear Information System (INIS)

    A key comparison has been made between the air-kerma standards of the ENEA-INMRI, Italy and the BIPM in the low-energy x-ray range. The results show the standards to be in agreement at the level of the standard uncertainty for the comparison of 1.9 parts in 103. No significant trend with radiation quality is observed. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. (authors)

  12. Implementation of the method air-kerma product area in KAP camera calibration with reference qualities of X-ray series at the SSDL RQR of Mexico; Implementacion del metodo producto kerma en aire-area en la calibracion de camaras KAP con calidades de referencia de rayos X de la serie RQR en el LSCD de Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Cejudo, Jesus; Tovar, Victor M., E-mail: jesus.cejudo@ini.gob.mx, E-mail: victor.tovar@inin.gob.mx [lnstituto Nacional de lnvestigaciones Nucleares (DMRI/LSDC/lNlN), Ocoyoacac (Mexico). Centro Nuclear Dr. Nabor Carrillo Flores. Laboratorio Secundario de Calibracion Dosimetrica

    2013-10-01

    The X-Ray machines, at a reference laboratory for the instrument calibration in diagnostic radiology, should compliance with the ISO requirements. Sometimes there is not available as much laboratories as needed in Latin American countries. So this project shows the KAP ionization chamber implementation method using the TRS-457 radiation quality from the IAEA at the SSDL of Mexico. The KAP instruments calibration method consists in doing a substitution comparison using a standard reference with traceability to a primary laboratory and a transmission-monitoring chamber that measures the number of photons of the X-ray primary beam. A KAP chamber calibration requires a special array that consists in collocating the chamber in two different positions of its calibration process. Then, with air kerma-area product coefficient together with a corrected electrometer measure at referential conditions, the patient dosimetry magnitudes are calculated. The dosimetry necessity at hospitals always will be in function of possessing a highly reliable calibration coefficient chamber for making these measures. That dosimetry results will help in reducing the total or partial irradiation emitted to the human body of the patient. This is how stochastic risks will be lessened due to diagnostic studies. The purpose of this project is to have a synergy with calibration for making known that the SSDL of Mexico has the technical capacity to act as a link between primary standard dosimetry laboratories and the ionizing radiation equipment users who require that their KAP chamber have traceability from the primary standard to the user. (author)

  13. Kinematic kerma factors

    International Nuclear Information System (INIS)

    The HEATR module of NJOY computes heat production by energy-balance (usually); that is, it assumes that the energy available for charged-particle emission and nuclear recoil can be obtained from the available energy (E + Q) minus the energy carried away by neutrons (E/sub n/) and the energy carried away by photons (anti E/sub ?/). If there are errors in either anti E/sub n/ or anti E /sub ?/, the local heating will be incorrect. In a large enough system, this heating error will be exactly compensated for by photon energy deposition, and the correct result for total heating will be obtained. However, in very small systems where most of the photons escape, the local heating can have very large errors resulting from a lack of energy conservation in the nuclear data evaluation. Accurate values for this local heating can be computed for some reactions by kinematics (radiative capture, elastic and inelastic neutron scattering). Reactions that emit charged particles are more difficult because the ENDF/B files do not contain the required particle spectra or angular distributions. Nevertheless, it is possible to establish an upper limit for the kinematic kerma factor by assuming that such reactions emit no photons. The HEATR module has been modified to add kinematic kerma factors computed in this way to the NJOY calculational path. This means that they are available for either multigroup or Monte Carlo processing

  14. Measurement of conversion coefficients between air Kerma and personal dose equivalent and backscatter factors for diagnostic X-ray beams; Determinacao experimental dos coeficientes de conversao de Kerma no ar para o equivalente de dose pessoal, Hp(d), e fatores de retroespalhamento em feixes de raios-x diagnostico

    Energy Technology Data Exchange (ETDEWEB)

    Rosado, Paulo Henrique Goncalves

    2008-07-01

    Two sets of quantities are import in radiological protection: the protection and operational quantities. Both sets can be related to basic physical quantities such as kerma through conversion coefficients. For diagnostic x-ray beams the conversion coefficients and backscatter factors have not been determined yet, those parameters are need for calibrating dosimeters that will be used to determine the personal dose equivalent or the entrance skin dose. Conversion coefficients between air kerma and personal dose equivalent and backscatter factors were experimentally determined for the diagnostic x-ray qualities RQR and RQA recommended by the International Electrotechnical Commission (IEC). The air kerma in the phantom and the mean energy of the spectrum were measured for such purpose. Harshaw LiF-100H thermoluminescent dosemeters (TLD) were used for measurements after being calibrated against an 180 cm{sup 3} Radcal Corporation ionization chamber traceable to a reference laboratory. A 300 mm x 300 mm x 150 mm polymethylmethacrylate (PMMA) slab phantom was used for deep-dose measurements. Tl dosemeters were placed in the central axis of the x-ray beam at 5, 10, 15, 25 and 35 mm depth in the phantom upstream the beam direction Another required parameter for determining the conversion coefficients from was the mean energy of the x-ray spectrum. The spectroscopy of x-ray beams was done with a CdTe semiconductor detector that was calibrated with {sup 133} Ba, {sup 241} Am and {sup 57} Co radiation sources. Measurements of the x-ray spectra were carried out for all RQR and RQA IEC qualities. Corrections due to the detector intrinsic efficiency, total energy absorption, escape fraction of the characteristic x-rays, Compton effect and attenuation in the detector were done aiming an the accurate determination of the mean energy. Measured x-ray spectra were corrected with the stripping method by using these response functions. The typical combined standard uncertainties of conversion coefficients and backscatter factors were 12% and 6% respectively. (author)

  15. SOIL{sub R}AD. A computer program to calculate air kerma, ambient dose rate and effective dose rate due to photons emitted by radionuclides distributed in soil on the soil-air surface

    Energy Technology Data Exchange (ETDEWEB)

    Blaauboer, R.O.

    1995-07-01

    In several research projects on environmental radiation there is a need for an automated system to calculate, for instance, the kerma in air or ambient dose rate that results from photons emitted by radionuclides in soil or on the soil surface. Some applications are migration of fallout radionuclides in soil, calculation of the shielding effect of soil due to landfill and the calculation of dose rate due to the naturally occurring radionuclides in soil. In the framework of an investigation aimed at determining the natural radiation background using the National Radioactivity Monitoring network (NRM), a computer application was developed for this purpose. In this report the underlying calculation method is described. An already existing method was adapted and expanded. Besides a description of this method, the structure of the SOIL{sub R}AD program is illustrated and instructions for use are given. Comparison of the first results to data published elsewhere confirms the usefulness of the program. 13 figs., 4 tabs., 20 refs., 3 appendices.

  16. A new method for calculation of an air quality index

    Energy Technology Data Exchange (ETDEWEB)

    Ilvessalo, P. [Finnish Meteorological Inst., Helsinki (Finland). Air Quality Dept.

    1995-12-31

    Air quality measurement programs in Finnish towns have expanded during the last few years. As a result of this it is more and more difficult to make use of all the measured concentration data. Citizens of Finnish towns are nowadays taking more of an interest in the air quality of their surroundings. The need to describe air quality in a simplified form has increased. Air quality indices permit the presentation of air quality data in such a way that prevailing conditions are more easily understandable than when using concentration data as such. Using an air quality index always means that some of the information about concentrations of contaminants in the air will be lost. How much information is possible to extract from a single index number depends on the calculation method. A new method for the calculation of an air quality index has been developed. This index always indicates the overstepping of an air quality guideline level. The calculation of this air quality index is performed using the concentrations of all the contaminants measured. The index gives information both about the prevailing air quality and also the short-term trend. It can also warn about the expected exceeding of guidelines due to one or several contaminants. The new index is especially suitable for the real-time monitoring and notification of air quality values. The behaviour of the index was studied using material from a measurement period in the spring of 1994 in Kaepylae, Helsinki. Material from a pre-operational period in the town of Oulu was also available. (author)

  17. Key Comparison APMP.RI(I)-K2 of air kerma standards for the CCRI reference radiation qualities for low-energy x-rays, including a supplementary comparison for the ISO 4037 narrow spectrum series

    International Nuclear Information System (INIS)

    An indirect comparison was performed between nine national standards for air kerma for the CCRI radiation qualities from 10 kV to 50 kV (APMP.RI(I)-K2) and for the ISO 4037 narrow spectrum series (15 kV and 40 kV). Among the nine institutes that participated in the comparison, seven institutes were APMP member laboratories. Three commercially available thin window parallel plate ionization chambers were used as transfer instruments and circulated among the participants. The pilot laboratory, the NMIJ/AIST, served also as the link to the corresponding BIPM.RI(I)-K2 comparison. The results show general agreement within the combined uncertainties, although certain results for Nuclear Malaysia, the BARC and the OAP show larger differences. (authors)

  18. Refractive index of air for interferometric length measurements

    Science.gov (United States)

    Abou-Zeid, A.

    2015-02-01

    The refractive index of air can be directly measured by a refractometer or can be calculated by using updated Edlén's formulas by measuring the parameters of the surrounding air or by using the modified two-colour method. In this paper an overview on the three methods is given by taking into account for their features, uncertainties and application fields.

  19. Neutron KERMA factors of Human Tissues

    OpenAIRE

    Martin-Martin, A.; J.L. Gutierrez-Villanueva; Barquero, R.; Manzanares-Acuña, E.; H. R. Vega-Carrillo

    2007-01-01

    A program to calculate the neutron KERMA in human tissues has been developed. The program was developed in Mathcad and contains the neutron kerma factors of those elements that are present in different human tissues. Having the elemental composition of any human tissue the neutron kerma can be easily calculated. The program was tested using the elemental composition of tumor tissues such as sarcoma, melanoma, carcinoma and adenoid cystic. Neutron kerma for adipose and muscle tissue for normal...

  20. Hold your breath: A new index of air pollution

    International Nuclear Information System (INIS)

    Environmental quality and climate change have been discussed prominently as urgent problems that – due to air pollution – produce severe consequences affecting the everyday life of millions of people. Using a Multiple Indicators Multiple Causes (MIMIC) model, we calculate a new index of air pollution and provide a ranking for 122 countries for every fifth year between 1985 and 2005. The empirical analysis supports the Environmental Kuznets Curve (EKC) hypothesis and shows a significant influence of determinants such as energy efficiency, industrial production, the electricity produced from coal sources, and demographic transition on air pollution. According to the index, Norway, Switzerland, Japan, Luxembourg, and Iceland are among the top 5 countries in terms of air quality performance. Eritrea, Mozambique, Tajikistan, the Democratic Republic of Congo, and Ethiopia performed worst in 2005. - Highlights: ? We calculate a new index of air pollution and provide a ranking for 122 countries. ? The empirical analysis supports the EKC hypothesis. ? Country ranking of this air pollution index is comparable across the period 1985 to 2005. ? Definition of the underlying variables does not change and the methodology is consistent

  1. The air pollution index system in Hong Kong

    Energy Technology Data Exchange (ETDEWEB)

    Lee, F.Y.P.; Gervat, G.P. [Hong Kong Government, Wanchai (Hong Kong). Environmental Protection Dept.

    1995-12-31

    The Hong Kong Environmental Protection Department (EPD) is currently operating an air quality monitoring network in the territory. There are nine monitoring stations, each with air quality monitoring equipment, meteorological instruments and a data logger. Five minute averaged data are transmitted through telephone lines to the central computer at the EPD Air Laboratory and are also stored in the data logger on site, as backup. At present, the EPD releases its air quality measurements to the public via monthly and special press releases, and annual reports. However, as public awareness of air pollution problems has increased, there has been an urgent need for timely and simpler information about air pollution levels. The development and operation of an Air Pollution Index (API) system has addressed that need. This presentation discusses the API computation, the information and advice released to the general public and how they can access the API information. Some API results are also presented. (author)

  2. The use of air quality index (AQI) in environmental management

    International Nuclear Information System (INIS)

    The air quality index (AQI) is considered a global air quality index in a particular moment or day and in a specific monitoring station. The AQI is to be interpreted as a guiding air quality index for the general public. Specialists should take into account other factors when studying the pollution levels. The behaviour of air pollution is studied by using the AQI in two monitoring points in Regla, where the main pollutants are measured: SO2, NO2 and total suspended particulates. It was founded that particulates and NO2 are the pollutants that contribute most to the air quality deterioration, which occurs with greater frequency-days in the categories Poor and Bad, and show an increase in the categories Terrible and Critical. The necessary recommendations for the reduction of air pollution are given. The use of this AQI for assessing air pollution in settlements is recommended as a good tool for environmental information and management. A visual scale is proposed to improve and facilitate the public's understanding

  3. Hold Your Breath. A New Index of Air Quality

    Energy Technology Data Exchange (ETDEWEB)

    Buehn, A. [Utrecht School of Economics, Utrecht University, Utrecht (Netherlands); Reza Farzanega, M. [Dresden University of Technology and ZEW Mannheim, Mannheim (Germany)

    2011-12-15

    Environmental quality and climate change have long attracted attention in policy debates. Recently, air quality has emerged on the policy agenda. We calculate a new index of air quality using CO2 and SO2 emissions per capita as indicators and provide a ranking for 122 countries from 1985 to 2005.The empirical analysis supports the EKC hypothesis (Environmental Kuznets Curve) and shows a significant influence of determinants such as energy efficiency, industrial production, electricity produced from coal sources, and urbanization on air quality. According to our index, Luxemburg, Norway, Iceland, Switzerland, and Japan are among the top 5 countries in terms of air quality performance. The Democratic Republic of Congo, Eritrea, Ethiopia, Togo, and Nepal performed worst in 2005.

  4. Hold Your Breath. A New Index of Air Quality

    International Nuclear Information System (INIS)

    Environmental quality and climate change have long attracted attention in policy debates. Recently, air quality has emerged on the policy agenda. We calculate a new index of air quality using CO2 and SO2 emissions per capita as indicators and provide a ranking for 122 countries from 1985 to 2005.The empirical analysis supports the EKC hypothesis (Environmental Kuznets Curve) and shows a significant influence of determinants such as energy efficiency, industrial production, electricity produced from coal sources, and urbanization on air quality. According to our index, Luxemburg, Norway, Iceland, Switzerland, and Japan are among the top 5 countries in terms of air quality performance. The Democratic Republic of Congo, Eritrea, Ethiopia, Togo, and Nepal performed worst in 2005.

  5. Hold your breath: A new index of air quality

    OpenAIRE

    Buehn, Andreas; Farzanegan, Mohammad Reza

    2012-01-01

    Environmental quality and climate change have long attracted attention in policy debates. Recently, air quality has emerged on the policy agenda. We calculate a new index of air quality using CO2 and SO2 emissions per capita as indicators and provide a ranking for 122 countries from 1985 to 2005. The empirical analysis supports the EKC hypothesis and shows a significant influence of determinants such as energy efficiency, industrial production, electricity produced from coal sources, and urba...

  6. Seasonal ARIMA for Forecasting Air Pollution Index: A Case Study

    OpenAIRE

    Muhammad H. Lee; Nur H.A. Rahman; Suhartono .; Latif, Mohd T.; Maria E. Nor; Nur A.B. Kamisan

    2012-01-01

    Problem statement: Both developed and developing countries are the major reason that affects the world environment quality. In that case, without limit or warning, this pollution may affect human health, agricultural, forest species and ecosystems. Therefore, the aim of this study was to determine the monthly and seasonal variations of Air Pollution Index (API) at all monitoring stations in Johor. Approach: In this study, time series models will be discussed to analyze future air quality and ...

  7. Air pollution forecast in cities by an air pollution index highly correlated with meteorological variables

    International Nuclear Information System (INIS)

    There are many different air pollution indexes which represent the global urban air pollution situation. The daily index studied here is also highly correlated with meteorological variables and this index is capable of identifying those variables that significantly affect the air pollution. The index is connected with attention levels of NO2, CO and O3 concentrations. The attention levels are fixed by a law proposed by the Italian Ministries of Health and Environment. The relation of that index with some meteorological variables is analysed by the linear multiple partial correlation statistical method. Florence, Milan and Vicence were selected to show the correlation among the air pollution index and the daily thermic excursion, the previous day's air pollution index and the wind speed. During the January-March period the correlation coefficient reaches 0.85 at Milan. The deterministic methods of forecasting air pollution concentrations show very high evaluation errors and are applied on limited areas around the observation stations, as opposed to the whole urban areas. The global air pollution, instead of the concentrations at specific observation stations, allows the evaluation of the level of the sanitary risk regarding the whole urban population. (Author)

  8. Alberta's air quality index : facts at your fingertip

    International Nuclear Information System (INIS)

    Alberta Environment measures the airborne concentrations of carbon dioxide, fine particulate matter, nitrogen dioxide, ozone and sulphur dioxide on a continuous basis at air quality monitoring stations in Edmonton, Calgary, Red Deer and Beaverlodge. Every hour, the readings are converted to an Air Quality Index (AQI) number to report on Alberta's outdoor air quality as either good, fair, poor or very poor. The categories relate to guidelines under Alberta's Environmental Protection and Enhancement Act and reflect the maximum acceptable levels specified by the National Ambient Air Quality Objectives. Current air quality conditions are available to the public through Alberta Environment's web site or by phoning a toll free number. Both Edmonton and Calgary report good air quality at least 90 per cent of the time. Occasionally, air quality in the two cities may reach the fair category, but it is seldom poor. Fair, poor or very poor air quality occurs with strong temperature inversion and light winds. Under these conditions, air pollutants, usually from automobiles, are trapped in a layer of stagnant air. Fair and poor air quality can also be caused by summer heat when photochemical smog forms by chemical reactions with oxides of nitrogen and volatile hydrocarbons. 1 ref., 1 tab., 1 fig

  9. Comparison of air kerma-length product measurements between the PTB and the IAEA for x-radiation qualities used in computed tomography (EURAMET.RI(I)-S12, EURAMET project 1327)

    International Nuclear Information System (INIS)

    A comparison of air kerma-length product determinations for standard radiation qualities defined for use in computed tomography (CT) was performed between the PTB and the IAEA as EURAMET project 1327, registered in the KCDB as the EURAMET.RI(I)-S12 comparison. A pencil type reference-class ionization chamber of the IAEA and the three RQT beam qualities established according to the IEC standard 61627:2005 were selected for the comparison. The calibration coefficients for the transfer chamber in terms of Gy cm/C at the PTB and the IAEA using the partial irradiation method recommended in the IAEA TRS 457 were determined. The results show the calibration coefficients of both laboratories were in a very good agreement of about 0.2 % well within the estimated relative standard uncertainty of the comparison of about 0.8 %. Residual correction due to the additional aperture required for partial irradiation of pencil chambers and feasibility of the full irradiation method were also studied. (authors)

  10. Calculation of neutron kerma in tissues

    International Nuclear Information System (INIS)

    Neutron kerma of normal and tumor tissues has been calculated using the tissues elemental concentration. A program developed in Math cad contains the kerma factors of C, H, O, N, Na, Mg, P, S, Cl, K, etc. that are in normal and tumor human tissues. Having the elemental composition of any human tissue the neutron kerma can be calculated. The program was tested using the elemental composition of tumor tissues such as sarcoma, melanoma, carcinoma and adenoid cystic, also neutron kerma for adipose and muscle tissue for normal adult was calculated. The results are in agreement with those published in literature. The neutron kerma for water was also calculated because in some dosimetric calculations water is used to describe normal and tumor tissues. From this comparison was found that at larger energies kerma factors are approximately the same, but energies less than 100 eV the differences are large. (Author)

  11. Comparison of the air-kerma standards of the ENEA-INMRI and the BIPM in the medium-energy X-ray range

    International Nuclear Information System (INIS)

    An indirect comparison has been made between the air erma standards of the ENEA-INMRI and the BIPM in the medium-energy x-ray range. The results show the standards to be in general agreement within the stated uncertainty, although there is evidence of a trend in the results at different radiation qualities. (authors)

  12. KERMA received in neck by woman subject to mammography survey

    International Nuclear Information System (INIS)

    This paper provides information about the Air KERMA received in the neck by women subjected to mammography surveys. In this investigation we demonstrated that the protection given in mammography units is insufficient because the neck protector is only made up of plastic, in consequence the neck receives unnecessary doses. We used for the radiological survey an Electrometer RADCAL, model: 9060, serial 99-1724 and an Ionization Chamber 180 cc. RADCAL, model: 10X5-60, serial: 18304.We carried out 15 Quality Control inspections in different mammography units used for screening breast cancer from different manufacturers and these QC inspections included radiological surveys. These inspections were made in a two year period. The ionization chamber was placed around the thyroid protector (left, front and right) and the Air KERMA was measured under clinical condition. We found inadequate protection in the thyroid protector. The Air KERMA around the thyroid protector was between 40 and 80 mGy/min. This investigation demonstrates that is impossible to postpone the need to demand mammography manufacturer to modify and reinforce the thyroid protector, and we urge all International Radiological Protection Association to take steps to insure the well being of our patients and to pursuit manufacturers to meet security standards required in order to reduce the exposure of the patient's neck. (author)

  13. In-patient to isocenter KERMA ratios in CT

    Energy Technology Data Exchange (ETDEWEB)

    Huda, Walter; Ogden, Kent M.; Lavallee, Robert L.; Roskopf, Marsha L.; Scalzetti, Ernest M. [Department of Radiology and Radiological Science, Medical University of South Carolina (MUSC), 96 Jonathan Lucas Street (MSC 323), Charleston, South Carolina 29425-3230 (United States); Department of Radiology, SUNY Upstate Medical University, 750 E Adams Street, Syracuse, New York 13210 (United States)

    2011-10-15

    Purpose: To estimate in-patient KERMA for specific organs in computed tomography (CT) scanning using ratios to isocenter free-in-air KERMA obtained using a Rando phantom.Method: A CT scan of an anthropomorphic phantom results in an air KERMA K at a selected phantom location and air kerma K{sub CT} at the CT scanner isocenter when the scan is repeated in the absence of the phantom. The authors define the KERMA ratio (R{sub K}) as K/ K{sub CT}, which were experimentally determined in a Male Rando Phantom using lithium fluoride chips (TLD-100). R{sub K} values were obtained for a total of 400 individual point locations, as well as for 25 individual organs of interest in CT dosimetry. CT examinations of Rando were performed on a GE LightSpeed Ultra scanner operated at 80 kV, 120 kV, and 140 kV, as well as a Siemens Sensation 16 operated at 120 kV. Results: At 120 kV, median R{sub K} values for the GE and Siemens scanners were 0.60 and 0.64, respectively. The 10th percentile R{sub K} values ranged from 0.34 at 80 kV to 0.54 at 140 kV, and the 90th percentile R{sub K} values ranged from 0.64 at 80 kV to 0.78 at 140 kV. The average R{sub K} for the 25 Rando organs at 120 kV was 0.61 {+-} 0.08. Average R{sub K} values in the head, chest, and abdomen showed little variation. Relative to R{sub K} values in the head, chest, and abdomen obtained at 120 kV, R{sub K} values were about 12% lower in the pelvis and about 58% higher in the cervical spine region. Average R{sub K} values were about 6% higher on the Siemens Sensation 16 scanner than the GE LightSpeed Ultra. Reducing the x-ray tube voltage from 120 kV to 80 kV resulted in an average reduction in R{sub K} value of 34%, whereas increasing the x-ray tube voltage to 140 kV increased the average R{sub K} value by 9%. Conclusions: In-patient to isocenter relative KERMA values in Rando phantom can be used to estimate organ doses in similar sized adults undergoing CT examinations from easily measured air KERMA values at the isocenter (free in air). Conversion from in-patient air KERMA values to tissue dose would require the use of energy-appropriate conversion factors.

  14. Seasonal ARIMA for Forecasting Air Pollution Index: A Case Study

    Directory of Open Access Journals (Sweden)

    Muhammad H. Lee

    2012-01-01

    Full Text Available Problem statement: Both developed and developing countries are the major reason that affects the world environment quality. In that case, without limit or warning, this pollution may affect human health, agricultural, forest species and ecosystems. Therefore, the aim of this study was to determine the monthly and seasonal variations of Air Pollution Index (API at all monitoring stations in Johor. Approach: In this study, time series models will be discussed to analyze future air quality and used in modeling and forecasting monthly future air quality in Malaysia. A Box-Jenkins ARIMA approach was applied in order to analyze the API values in Johor. Results: In all this three stations, high values recorded at sekolah menengah pasir gudang dua (CA0001. This situation indicates that the most polluted area in Johor located in Pasir Gudang. This condition appears to be the reason that Pasir Gudang is the most developed area especially in industrial activities. Conclusion: Time series model used in forecasting is an important tool in monitoring and controlling the air quality condition. It is useful to take quick action before the situations worsen in the long run. In that case, better model performance is crucial to achieve good air quality forecasting. Moreover, the pollutants must in consideration in analysis air pollution data.

  15. Experimental comparison among the laboratories accredited within the framework of the European Co-operation for Accreditation on the calibration of a radiation protection dosimeters in the terms of the quantity air Kerma

    International Nuclear Information System (INIS)

    The European co-operation for Accreditation (EA) formalises the collaboration of the Accreditation Bodies of the Member States of the European Union and the European Free Trade Association covering all conformity assessment activities. This collaboration is based on a Memorandum of Understanding dated the 27 November 1997 and aims at developing and maintain Multilateral Agreements (MLAs) within EA and with non-members accreditation bodies. MLAs Signatories guarantee uniformity of accreditation by continuous and rigorous evaluation. Based on mutual confidence, the MLAs recognise the equivalence of the accreditation systems administered by EA Members and of certificates and reports issued by bodies accredited under these systems. A basic element of the program to establish and maintain mutual confidence among calibration services is the participation of the accredited laboratories in experimental interlaboratory comparisons (ILC) organised by EA members or other international organisations. The aim of these ILC is to verify the technical equivalence of calibration services within the EA. The ILC which it is dealt with in the present work was recently carried out over a period of two years, ending in May 2002. It interested the laboratories accredited in the ionising radiation field for calibration of dosimeters at radiation protection levels in terms of the quantity air kerma (Kair) due to 60Co and 137Cs gamma radiation. The ILC was planned by the EA expert group on Ionising radiation and radioactivity and approved by the EA General Assembly in December 1999 with the title Calibration of a Radiation Protection Dosimeter under the code IR3. The need of this comparison also resulted from an inquiry carried out in 1998 by the expert group among the different Accreditation Bodies members of EA and associated to EA. The organization of the ILC was carried out according to the EA rules by the Italian Accreditation Body in the ionising radiation field, the SIT-ENEA , in cooperation with the Italian National Metrology Institute in the ionising radiation field, the ENEA-INMRI, as the reference laboratory

  16. An innovative approach for determination of air quality health index.

    Science.gov (United States)

    Gorai, Amit Kumar; Kanchan; Upadhyay, Abhishek; Tuluri, Francis; Goyal, Pramila; Tchounwou, Paul B

    2015-11-15

    Fuzzy-analytical hierarchical process (F-AHP) can be extended to determine fuzzy air quality health index (FAQHI) for deducing health risk associated with local air pollution levels, and subjective parameters. The present work aims at determining FAQHI by considering five air pollutant parameters (SO2, NO2, O3, CO, and PM10) and three subjective parameters (population sensitivity, population density and location sensitivity). Each of the individual pollutants has varying impacts. Hence the combined health effects associated with the pollutants were estimated by aggregating the pollutants with different weights. Global weights for each evaluation alternatives were determined using fuzzy-AHP method. The developed model was applied to determine FAQHI in Howrah City, India from daily-observed concentrations of air pollutants over the three-year period between 2009 and 2011. The FAQHI values obtained through this method in Howrah City range from 1 to 3. Since the permissible value of FAQHI (as calculated for NAAQS) for residential areas is 1.78, higher index values are of public health concern to the exposed individuals. During the period of study, the observed FAQHI values were found to be higher than 1.78 in most of the day in the months of January to March, and October to December. However, the index values were below the recommended limit during rest of the months. In conclusion, FAQHI in Howrah city was above permissible limit in winter months and within acceptable values in summer and rainy months. Diurnal variations of FAQHI showed a similar trend during the three-year period of assessment. PMID:26186464

  17. AIRS-CloudSat cloud mask and radar reflectivities collocation indexes V3.1

    Data.gov (United States)

    National Aeronautics and Space Administration — This is AIRS-AMSU-CloudSat collocation indexes, in ASCII format. These data map CloudSat profile indexes to the collocated AMSU field of views, and AIRS IR...

  18. The Air Quality Health Index and Asthma Morbidity: A Population-Based Study

    OpenAIRE

    To, Teresa; Shen, Shixin; Atenafu, Eshetu G.; Guan, Jun; McLimont, Susan; Stocks, Brian; Licskai, Christopher

    2012-01-01

    Background: Exposure to air pollution has been linked to the exacerbation of respiratory diseases. The Air Quality Health Index (AQHI), developed in Canada, is a new health risk scale for reporting air quality and advising risk reduction actions.

  19. Comparison of conversion coefficients for equivalent dose in terms of air kerma using a sitting and standing female adult voxel simulators exposure to photons in antero-posterior irradiation geometry

    International Nuclear Information System (INIS)

    Due to the difficulty in implementing invasive techniques for calculations of dose for some exposure scenarios, computational simulators have been created to represent as realistically as possible the structures of the human body and through radiation transport simulations to obtain conversion coefficients (CCs) to estimate dose. In most published papers simulators are implemented in the standing posture and this may not describe a real scenario of exposure. In this work we developed exposure scenarios in the Visual Monte Carlo (VMC) code using a female simulator in standing and sitting postures. The simulator was irradiated in the antero-posterior (AP) geometry by a plane source of monoenergetic photons with energy from 10 keV to 2 MeV. The conversion coefficients for equivalent dose in terms of air kerma (HT/Kair) were calculated for both scenarios and compared. The results show that the percentage difference of CCs for the organs of the head and thorax was not significant (less than 5%) since the anatomic position of the organs is the same in both postures. The percentage difference is more significant to the ovaries (71% for photon energy of 20 keV), to the bladder (39% at 60 keV) and to the uterus (37% at 100 keV) due to different processes of radiation interactions in the legs of the simulator when its posture is changed. For organs and tissues that are distributed throughout the entire body, such as bone (21% at 100 keV) and muscle (30% at 80 keV) the percentage difference of CCs reflects a reduction of interaction of photons with the legs of the simulator. Therefore, the calculation of conversion coefficients using simulators in the sitting posture is relevant for a more accurate dose estimation in real exposures to radiation. - Highlights: ? Scenarios of external photon exposures were performed in VMC code. ? The FAX simulator was irradiated in sitting and standing postures. ? The irradiation geometry used was the antero-posterior (AP). ? The conversion coefficients for sitting and standing postures were compared. ? Photoelectric and Compton effects were the main processes of energy deposition

  20. Comparison of conversion coefficients for equivalent dose in terms of air kerma for photons using a male adult voxel simulator in sitting and standing posture with geometry of irradiation antero-posterior

    International Nuclear Information System (INIS)

    The dose conversion coefficient (DCC) is important to quantify and assess effective doses associated with medical, professional and public exposures. The calculation of DCCs using anthropomorphic simulators and radiation transport codes is justified since in-vivo measurement of effective dose is extremely difficult and not practical for occupational dosimetry. DCCs have been published by the ICRP using simulators in a standing posture, which is not always applicable to all exposure scenarios, providing an inaccurate dose estimation. The aim of this work was to calculate DCCs for equivalent dose in terms of air kerma (H/Kair) using the Visual Monte Carlo (VMC) code and the VOXTISS8 adult male voxel simulator in sitting and standing postures. In both postures, the simulator was irradiated by a plane source of monoenergetic photons in antero-posterior (AP) geometry. The photon energy ranged from 15 keV to 2 MeV. The DCCs for both postures were compared and the DCCs for the standing simulator were higher. For certain organs, the difference of DCCs were more significant, as in gonads (48% higher), bladder (16% higher) and colon (11% higher). As these organs are positioned in the abdominal region, the posture of the anthropomorphic simulator modifies the form in which the radiation is transported and how the energy is deposited. It was also noted that the average percentage difference of conversion coefficients was 33% for the bone marrow, 11% for the skin, 13% for the bone surface and 31% for the muscle. For other organs, the percentage difference of the DCCs for both postures was not relevant (less than 5%) due to no anatomical changes in the organs of the head, chest and upper abdomen. We can conclude that is important to obtain DCCs using different postures from those present in the scientific literature. - Highlights: • Scenarios of external photon exposures were performed in VMC code. • The VOXTISS8 simulator was irradiated in standing and sitting postures. • The irradiation geometry used was the antero-posterior (AP). • The DCCs for standing and sitting postures were compared. • Significant differences between the DCCs in both postures were observed

  1. DEFINITION OF NOVEL HEALTH AND AIR POLLUTION INDEX BASED ON SHORT TERM EXPOSURE AND AIR CONCENTRATION LEVELS

    OpenAIRE

    Pelliccioni, A.; Gariazzo, C.; M. De Dominicis

    2008-01-01

    Abstract: Health impact assessment has become important in the development of air quality policies and in finding the relationships between pollutants concentration and health effects. In our work we presented a novel index able to evaluate the effects on the human exposure caused by ambient air pollution in urban areas. The index is able to link both health risk factors and pollutants levels. The indexes is of additive type and is composed by two terms: the former is based on pollut...

  2. Neutron kerma coefficient: Reference tissue for tumours

    International Nuclear Information System (INIS)

    Neutron kerma coefficients were calculated in different media: 4 malignant tumours, 5 normal tissues and 3 tissue substitute in the range 11 eV-29 MeV. The objective was to identify which is the material that better reproduces the behavior of these tumours and tissues. These tissues have clinical interest in interstitial brachytherapy applications with fast neutron source (Cf-252). The small differences of elemental composition among these tissues produce variation in the neutron kerma coefficients. The results show that the neutron kerma coefficients for malignant tumours are smaller than soft tissue from 6% to 9%. Also, the muscle is the tissue that best represents the dosimetric behavior for the tumours and tissues analyzed in this paper for neutron energies >1 keV, where this coefficients show minor variation.

  3. High-precision diode-laser-based temperature measurement for air refractive index compensation

    OpenAIRE

    Hieta, Tuomas; Merimaa, Mikko; Vainio, Markku; SeppÀ, Jeremias; Lassila, Antti

    2011-01-01

    We present a laser-based system to measure the refractive index of air over a long path length. In optical distance measurements it is essential to know the refractive index of air with high accuracy. Commonly, the refractive index of air is calculated from the properties of the ambient air using either Ciddor or Edlén equations, where the dominant uncertainty component is in most cases the air temperature. The method developed in this work utilises direct absorption spectroscopy of oxygen t...

  4. Can the Air Pollution Index be used to communicate the health risks of air pollution?

    Science.gov (United States)

    Li, Li; Lin, Guo-Zhen; Liu, Hua-Zhang; Guo, Yuming; Ou, Chun-Quan; Chen, Ping-Yan

    2015-10-01

    The validity of using the Air Pollution Index (API) to assess health impacts of air pollution and potential modification by individual characteristics on air pollution effects remain uncertain. We applied distributed lag non-linear models (DLNMs) to assess associations of daily API, specific pollution indices for PM10, SO2, NO2 and the weighted combined API (APIw) with mortality during 2003-2011 in Guangzhou, China. An increase of 10 in API was associated with a 0.88% (95% confidence interval (CI): 0.50, 1.27%) increase of non-accidental mortality at lag 0-2 days. Harvesting effects appeared after 2 days' exposure. The effect estimate of API over lag 0-15 days was statistically significant and similar with those of pollutant-specific indices and APIw. Stronger associations between API and mortality were observed in the elderly, females and residents with low educational attainment. In conclusion, the API can be used to communicate health risks of air pollution. PMID:26057478

  5. Vessel heave, and index for air bubble attenuation corrections

    OpenAIRE

    Ona, Egil

    1991-01-01

    The possible use of vessel heave as a correction indicator for air bubble attenuation of acoustic signals from hull mounted transducers is investigated. Vessel heave was monitored along with the echo energy from the air bubble layer close to the transducer surface. Initial comparisons under different weather conditions are presented.

  6. Tolerance Levels of Roadside Trees to Air Pollutants Based on Relative Growth Rate and Air Pollution Tolerance Index

    OpenAIRE

    SULISTIJORINI; ZAINAL ALIM MAS’UD; NIZAR NASRULLAH; AHMAD BEY; SOEKISMAN TJITROSEMITO

    2008-01-01

    Motor vehicles release carbon monoxide, nitrogen dioxide, sulphur dioxide, and particulate matters to the air as pollutants. Vegetation can absorb these pollutants through gas exchange processes. The objective of this study was to examine the combination of the relative growth rate (RGR) and physiological responses in determining tolerance levels of plant species to air pollutants. Physiological responses were calculated as air pollution tolerance index (APTI). Eight roadside tree species wer...

  7. Neutron kerma coefficients of compounds for shielding and dosimetry

    International Nuclear Information System (INIS)

    Highlights: • Neutron kerma coefficients of compounds were calculated. • Kerma coefficients are lowest in intermediate energy (10 eV–10 keV). • Kerma coefficients are large for compounds containing large low-Z elements. • Resonance in kerma coefficients is observed for the oxygen containing compounds. • At larger energies kerma coefficients are approximately the same. - Abstract: Alloys, concretes, glasses, neutron shielding material, polymers, nuclear track detectors, are being used for shielding and dosimetry applications. The neutron kerma coefficients of eighteen compounds have been calculated for neutrons energy less than 30 MeV; these compounds are used as shielding and dosimetric materials. The kerma coefficients are found lowest for all the compounds in intermediate energy (10 eV < E < 10 keV). The neutron kerma coefficients are higher for the compounds containing large weight fraction of low-Z elements. A resonance in neutron kerma coefficient is observed for the large amount of oxygen containing compounds. It is found that at high energies kerma coefficients are approximately same, but very large differences for energy less than 100 eV

  8. ZZ KERMAL, Neutron and Gamma Kerma Library from ENDL and EGDL

    International Nuclear Information System (INIS)

    Description of program or function: 1 - Calculated Neutron Kerma Factors: - Format: TART Monte Carlo neutron transport code; - Number of groups: 175 neutron energy groups; - Nuclides: tissue, bone, muscle, standard man, plastic,nylon-6.6/6, Lucite, liquid muscle equivalent, water, acetylene, dry air, water-saturated air, carbon dioxide, Ethylene, Te gas with methane. - Origin: LLNL Evaluated Nuclear Data Library (ENDL). 2 - Calculated Photon kerma Factors: - Format: TART Monte Carlo neutron transport code; - Number of groups: 191 energy groups; - Nuclides: tissue, bone, muscle, standard man, plastic,nylon-6.6/6, Lucite, liquid muscle equivalent, water, acetylene, dry air, water-saturated air, carbon dioxide, Ethylene, Te gas with methane. - Origin: LLNL Evaluated Gamma-Ray Data Library (ENDL). These libraries contain neutron and gamma ray Kerma factors. KENDL, the neutron Kerma factors have been calculated from the LLNL Evaluated Nuclear Data Library (ENDL) data file. The results are for the 175 neutron energy groups used by the TART Monte Carlo neutron transport code for isotopes and elemental mixtures. They are tabulated for 15 composite materials and for the isotopes or elements in the ENDL file from Z=1 to Z=29. The incident neutron energies range from 1.882 x 1.0 E-5 to 20 MeV for the composite materials and from 1.307 x 1.0 E-9 to 20 MeV for the isotopes and elements. KEGDL, the gamma-ray KERMA factors calculated from the LLNL Evaluated Gamma-Ray Data Library (EGDL) file, are tabulated for the elements from Z=1 to Z=30 and for 15 composite materials. The KERMA factors are presented for 191 energy groups over the incident photon energy range from 100 eV to 100 MeV. The following composite materials are tabulated: tissue, bone, muscle, standard man, plastic, nylon-6.6/6, Lucite, liquid muscle equivalent, water, acetylene, dry air, water-saturated air, carbon dioxide, gas Te with methane

  9. Air refractivity index in optical region: formulas and measurement in CZ.

    Czech Academy of Sciences Publication Activity Database

    Pešice, Petr; Fišer, Ond?ej; Chládová, Zuzana; Brázda, Vladimír

    Portsmouth : University of Portsmouth, 2012, COST IC0802/1-COST IC0802/7. [MCM 7. Portsmouth (GB), 16.04.2012-18.04.2012] R&D Projects: GA MŠk OC09027 Institutional support: RVO:68378289 Keywords : Refractivity index * structure index * free-space optics * temperature * humidity * air pressure Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  10. Tissue kerma vs distance relationships for initial nuclear radiation from the atomic bombs Hiroshima and Nagasaki

    International Nuclear Information System (INIS)

    Initial nuclear radiation is comprised of prompt neutrons and prompt primary gamma rays from an exploding nuclear device, prompt secondary gamma rays produced by neutron interactions in the environment, and delayed neutrons and delayed fission-product gamma rays from the fireball formed after the nuclear device explodes. These various components must all be considered in establishing tissue kerma vs distance relationships which describe the decrease of initial nuclear radiation with distance in Hiroshima and Nagasaki. An interest in initial nuclear radiation at distances of as much as 2000 m from the hypocenter demands the use of discrete ordinates transport (DOT) techniques. The two-dimensional (2D) DOT-IV code developed at Oak Ridge National Laboratory (ORNL) was used to calculate the tissue kerma in an air-over-ground geometry from prompt neutrons and prompt primary gamma rays and from prompt secondary gamma rays produced in air and in soil. Data from the Los Alamos National Laboratory (LANL) were used as the source terms. The tissue kerma at ground level from delayed fission-product gamma rays and delayed neutrons, was investigated using the NUIDEA code developed by Science Applications, Inc., (SAI). This code incorporates very detailed models which can take into account such features as the immediate rise of the fireball, the rapid radioactive decay of fission-products in it, and the perturbation of the atmosphere by the explosion. Tissue kerma vs distance relationships obtained by summing results of these current state-of-the-art calculations will be discussed. Our results clearly show that the prompt secondary gamma rays and delayed fission-product gamma rays are the dominant components of the total tissue kerma from initial nuclear radiation of the atomic (or pure-fission) devices detonated over Hiroshima and Nagasaki. (author)

  11. Survivor dosimetry. Part A. Fluence-to-kerma conversion coefficients

    International Nuclear Information System (INIS)

    An important step in the dosimetry evaluation is to relate the radiation passing through a unit volume of a material of interest (fluence) to the energy release (kerma) in the material, which determines the absorbed dose. The fluence-to-kerma conversion coefficients or 'kerma coefficients' used in the Dosimetry System 1986 (DS86) are taken from Kerr (1982). These kerma coefficients are based on body tissue compositions for Reference Man from the International Commission on Radiological Protection (1975) and Kerr (1982), the mass energy-absorption coefficients for photons from Hubbell (1982), and the elemental kerma coefficients for neutrons from Caswell et al. (1980). Hence, the kerma coefficients used in DS86 are approximately 20 years old. In order to provide an updated set of kerma coefficients for use in the Dosimetry System 2002 (DS02), a new evaluation has been completed. This new evaluation considered recently suggested changes in the composition of soft tissues of the body in ICRU Report 44 (International Commission on Radiation Units and Measurements 1989), the mass energy-absorption coefficients for photons by Hubbell and Seltzer (1996), and the elemental kerma coefficients for neutrons in ICRU Report 63 (International Commission on Radiation Units and Measurements 2000). The new DS02 kerma coefficients for soft tissue are presented as both point-wise data for use in Monte Carlo radiation transport calculations and multigroup data for use in discrete ordinates radiation transport calculations. (author)

  12. A comparative study for air pollution tolerance index of some terrestrial plant species

    OpenAIRE

    R.N. Lohe; B. Tyagi; Singh, V; P. Tyagi; D.R. Khanna; R. Bhutiani

    2015-01-01

    Although water and land pollution are very dangerous, air pollution has its own peculiarities due to its transboundary dispersion of pollutants over the entire world. In any well planned urban set up, industrial pollution takes a back seat and vehicular emissions take precedence as the major cause of urban air pollution. In the present study, Air pollution tolerance index was calculated for various plant species growing at two sites Nagal village at Sahastradhara Road and the Clock Tower (the...

  13. A comparative study for air pollution tolerance index of some terrestrial plant species

    Directory of Open Access Journals (Sweden)

    R.N. Lohe

    2015-09-01

    Full Text Available Although water and land pollution are very dangerous, air pollution has its own peculiarities due to its transboundary dispersion of pollutants over the entire world. In any well planned urban set up, industrial pollution takes a back seat and vehicular emissions take precedence as the major cause of urban air pollution. In the present study, Air pollution tolerance index was calculated for various plant species growing at two sites Nagal village at Sahastradhara Road and the Clock Tower (the experimental site of Dehradun city, India. The leaf samples were collected from 7 commonly present tree species. The results showed significant effects of various air pollutants on the vegetation in terms of four biochemical parameters analysed. Four physiological and biochemical parameters, which are leaf relative water content, Ascorbic acid content, total leaf chlorophyll content and leaf extract pH were used to compute the air pollution tolerance index values. Statistically significant difference was observed between control and experimental group for Ascorbic acid, t(6=-4.848,p=.003. Paired t test for air pollution tolerance index between the two groups showed a statistically significant difference, t (6 = -4.548, p=.004. On the basis of air pollution tolerance index values for above mentioned seven tree species, Eucalyptus globus exhibited the highest degree of tolerance at all the sites followed by Ficus religiosa > Mangifera indica > Polyalthia longifolia > Phyllanthus emblica > Citrus limon > Lantana camara.

  14. High-precision diode-laser-based temperature measurement for air refractive index compensation

    International Nuclear Information System (INIS)

    We present a laser-based system to measure the refractive index of air over a long path length. In optical distance measurements, it is essential to know the refractive index of air with high accuracy. Commonly, the refractive index of air is calculated from the properties of the ambient air using either Ciddor or Edlen equations, where the dominant uncertainty component is in most cases the air temperature. The method developed in this work utilizes direct absorption spectroscopy of oxygen to measure the average temperature of air and of water vapor to measure relative humidity. The method allows measurement of temperature and humidity over the same beam path as in optical distance measurement, providing spatially well-matching data. Indoor and outdoor measurements demonstrate the effectiveness of the method. In particular, we demonstrate an effective compensation of the refractive index of air in an interferometric length measurement at a time-variant and spatially nonhomogeneous temperature over a long time period. Further, we were able to demonstrate 7 mK RMS noise over a 67 m path length using a 120 s sample time. To our knowledge, this is the best temperature precision reported for a spectroscopic temperature measurement.

  15. Can the Air Pollution Index be used to communicate the health risks of air pollution?

    International Nuclear Information System (INIS)

    The validity of using the Air Pollution Index (API) to assess health impacts of air pollution and potential modification by individual characteristics on air pollution effects remain uncertain. We applied distributed lag non-linear models (DLNMs) to assess associations of daily API, specific pollution indices for PM10, SO2, NO2 and the weighted combined API (APIw) with mortality during 2003–2011 in Guangzhou, China. An increase of 10 in API was associated with a 0.88% (95% confidence interval (CI): 0.50, 1.27%) increase of non-accidental mortality at lag 0–2 days. Harvesting effects appeared after 2 days’ exposure. The effect estimate of API over lag 0–15 days was statistically significant and similar with those of pollutant-specific indices and APIw. Stronger associations between API and mortality were observed in the elderly, females and residents with low educational attainment. In conclusion, the API can be used to communicate health risks of air pollution. - Highlights: • The cumulative effects of API on mortality over lag 0–15 days remained significant. • The indices for three specific pollutants had similar associations with mortality. • The effects of API were modified by age, gender and educational attainment. • Our findings can help to communicate health risks of air pollution to the public. - The Air Pollution Index communicates health risks of air pollution

  16. Preparation and determination of kerma for Iridium 192 sources of low dose rate for brachytherapy

    International Nuclear Information System (INIS)

    The practice of Brachytherapy with Iridium-192 sources of low dose rate (0.4 - 0.8 Gy/h) is a technique used in the treatment of diverse illnesses. in this work the preparation, quality control and calibration are presented in terms of kerma in air of Iridium-192 using as target these recycled Iridium-Platinum wires. The targets were obtained as decayed sources of different radio therapeutical centers in the country and they were characterized by Scanning electron microscopy in order to determine their chemical composition. Subsequently it was developed an experimental design to establish the effect of neutron flux, geometrical array and irradiation time over the activity and percentage of the sources homogeneity. The homogeneity was determined by auto radiography and by Gamma spectroscopy. Once the optimal irradiation conditions were established, it is determined the apparent activity and kerma in air using a well type ionization chamber with traceability to a primary laboratory. Iridium-192 sources were obtained with an average homogeneity 96 %, apparent activity 282.129 ± 0.531 M Bq and kerma in air 0.03200 ± 0.00006 m Gy m/h A. (Author)

  17. Kerma factors in interaction of neutrons with boron carbide

    International Nuclear Information System (INIS)

    Heat generation in neutron interactions with boron carbide B10; B11 and 12C is calculated. Kerma-factors (kerma-kinetic energy released in materials) were calculated for neutron energies between 10-4 eV and 15 MeV. No major simplifying assumptions are introduced, and the accuracy of the calculated kerma-factors depends only on availability and accuracy of the basic nuclear data. The ENDF/B-4 data and recent experimental information are used for the calculation of kerma-factors. Plots of these kerma-factors are presented in units of eVxb/atom and wtxsec/(cmxn) as a function of neutron energy

  18. Suppression of Air Refractive Index Variations in High-Resolution Interferometry

    Directory of Open Access Journals (Sweden)

    Zden?k Buchta

    2011-08-01

    Full Text Available The influence of the refractive index of air has proven to be a major problem on the road to improvement of the uncertainty in interferometric displacement measurements. We propose an approach with two counter-measuring interferometers acting as a combination of tracking refractometer and a displacement interferometer referencing the wavelength of the laser source to a mechanical standard made of a material with ultra-low thermal expansion. This technique combines length measurement within a specified range with measurement of the refractive index fluctuations in one axis. Errors caused by different position of the interferometer laser beam and air sensors are thus eliminated. The method has been experimentally tested in comparison with the indirect measurement of the refractive index of air in a thermal controlled environment. Over a 1 K temperature range an agreement on the level of 5 × 10?8 has been achieved.

  19. Impact of fine particulate fluctuation and other variables on Beijing's air quality index.

    Science.gov (United States)

    Chen, Bo; Lu, Shaowei; Li, Shaoning; Wang, Bing

    2015-04-01

    We analyzed fluctuation in Beijing's air quality over 328 days, based on air quality grades and air quality data from 35 atmospheric monitoring stations. Our results show the air over Beijing is subject to pollution 152 days of the year, or 46.34%. Among all pollutants, fine particulates, solid or liquid, 2.5 ?m or less in size (PM2.5), appeared most frequently as the primary pollutant: 249 days, or 76% of the sample year (328 days). Nitrogen dioxide (NO2) and coarse particulates (PM10) cause the least pollution, appearing only 7 and 3 days, or 2 and 1% of the sample year, respectively. In Beijing, fine particulates like PM2.5 vary seasonally: 154.54?±?18.60 in winter?>?145.22?±?18.61 in spring?>?140.16?±?20.76 in autumn?>?122.37?±?13.42 in summer. Air quality is best in August and worst in December, while various districts in Beijing experience different air quality. To be specific, from south to north and from west to east, air quality tends to improve. Meteorological elements have a constraining effect on air pollutants, which means there is a linear correlation between the air quality index and humidity, rainfall, wind speed, and temperature. Under a typical pollution scenario, the higher the air quality index (AQI) value, the lower the wind speed and the greater the relative humidity; the lower the AQI value, the higher the wind speed and lower the relative humidity. Analysis of influencing factors reveals that the air pollution is mainly particulate matter produced by burning coal, vehicle emissions, volatile oils and gas, fast development of food services, emissions from the surrounding region, and natural dust clouds formed in arid areas to the northwest. Topography affects the distribution of meteorological conditions, in turn varying air quality over the region from one location to another. Human activities also exercise impact on urban air quality with dual functions. PMID:25563832

  20. Real-time compensation of the refractive index of air in distance measurement.

    Science.gov (United States)

    Kang, Hyun Jay; Chun, Byung Jae; Jang, Yoon-Soo; Kim, Young-Jin; Kim, Seung-Woo

    2015-10-01

    A two-color scheme of heterodyne laser interferometer is devised for distance measurements with the capability of real-time compensation of the refractive index of the ambient air. A fundamental wavelength of 1555 nm and its second harmonic wavelength of 777.5 nm are generated, with stabilization to the frequency comb of a femtosecond laser, to provide fractional stability of the order of 3.0 × 10(-12) at 1 s averaging. Achieved uncertainty is of the order of 10(-8) in measuring distances of 2.5 m without sensing the refractive index of air in adverse environmental conditions. PMID:26480151

  1. Measurement of air refractive index based on surface plasmon resonance and phase detection.

    Science.gov (United States)

    Chen, Qianghua; Luo, Huifu; Wang, Sumei; Wang, Feng

    2012-07-15

    A method for refractive index of air measurement is presented based on surface plasmon resonance (SPR) and phase detection using a dual-frequency laser interferometer. Theoretical analyses indicate that the phase-difference variation of the measurement signal versus the reference signal is linear with refractive index of air (RIA) fluctuation, and the calculation formula of RIA is derived. The structure design of the self-adaptive SPR sensor greatly reduces the measurement error resulting from the incident angle shift and improves the sensitivity. The experiments show that measurement uncertainty of 10(-6) order has been achieved when phase detection precision is 0.1°. The phenomenon of sudden phase variation during air pumping and air filling, which is caused by temperature fluctuation, is discussed. PMID:22825177

  2. Arima and integrated arfima models for forecasting air pollution index in Shah Alam, Selangor

    International Nuclear Information System (INIS)

    Air pollution is one of the major issues that has been affecting human health, agricultural crops, forest species and ecosystems. Since 1980, Malaysia has had a series of haze episodes and the worst ever was reported in 1997. As a result, the government has established the Malaysia Air Quality Guidelines, the Air Pollution Index (API) and Haze Action Plan, to improve the air quality. The API was introduced as an index system for classifying and reporting the ambient air quality in Malaysia. The API for a given period is calculated based on the sub-index value (sub-API) for all the five air pollutants, namely sulphur dioxide (SO2), nitrogen dioxide (NO2), ozone (O3), carbon monoxide (CO) and particulate matter below 10 micron size (PM10). The forecast of air pollution can be used for air pollution assessment and management. It can serve as information and warning to the public in cases of high air pollution levels and for policy management of many different chemical compounds. Hence, the objective of this project is to fit and illustrate the use of time series models in forecasting the API in Shah Alam, Selangor. The data used in this study consists of 70 monthly observations of API (from March 1998 to December 2003) published in the Annual Reports of the Department of Environment, Selangor. The time series models that were being considered were the Integrated Autoregressive Moving Average (ARIMA) and the Integrated Long Memory Model (ARFIMA) models. The lowest MAE, RMSE and MAPE values were used as the model selection criteria. Between these two models considered, the integrated ARFIMA model appears to be the better model as it has the lowest MAPE value. However, the actual value of May 2003 falls outside the 95% forecast interval, probably due to emissions from mobile sources (i.e., motor vehicles), industrial emissions, burning of solid wastes and forest fires. (author)

  3. Effect of scintillometer height on structure parameter of the refractive index of air measurements

    Science.gov (United States)

    Scintillometers measure amount of scintillations by emitting a beam of light over a horizontal path and expresses as the atmospheric turbulence structure parameter as the refractive index of air (Cn**2). Cn**2 represents the turbulent strength of the atmosphere and describes the ability of the atmos...

  4. Frequency measurement of refraction index of air for high-resolution laser interferometry.

    Czech Academy of Sciences Publication Activity Database

    ?íp, Ond?ej; Petr?, František; Matoušek, V.; Lazar, Josef

    Bellingham : SPIE, 2004, s. 273-277. ISBN 0-8194-5380-3. ISSN 0277-786X. [Optical Micro- and Nanometrology in Manufacturing Technology. Strasbourg (FR), 29.04.2004-30.04.2004] R&D Projects: GA AV ?R(CZ) IAB2065001 Keywords : index of refraction of air * high-resolution laser interferometry * Edlen formula Subject RIV: BH - Optics, Masers, Lasers

  5. The spatial- time distribution of vertical gradient of refraction index of air in territory of Mongolia

    International Nuclear Information System (INIS)

    The results of calculation of the vertical gradient of refraction index of air in 2-300 m layer of troposphere by 3 year (1987-1989) data of 8 meteorological stations in the Mongolia is been showed. Year course and integral distribution of g of this stations are described. 4 figs, 2 tables. (J.U)

  6. Index to the 1st through 16th AEC/ERDA/DOE nuclear air cleaning conferences

    International Nuclear Information System (INIS)

    The Proceedings of the sixteen conferences comprise a vertible encyclopedia on the technology of nuclear air and gas treatment and the control of airborne nuclear waste. These Proceedings cover the history of the technology; describe most of the research and developments in the field, worldwide, since the early 1950's; describe the problems that have been encountered and the solutions found to those problems; and summarize experience with equipment and systems developed for the control of airborne radioactive wastes in laboratory, radiochemical, and reactor operations, both government and commercial. The problem with this encyclopedia is that there has been no index to it; there has been no easy way for searching it to find what was available. This index fills the gap. The first conference was an informal meeting of a number of interested parties from among the then AEC contractors. Consequently, there were no proceedings for that meeting. The subsequent conferences, with their years, locations, and Proceedings numbers, are listed. This index consists of three parts: a tabulation of papers and their authors by paper number (Part I); a tabulation of papers and their paper numbers by author (Part II); and a key-word-in context (KWIC) index of papers. The paper number is a two-part designation consisting of the number of the conference (2, 3...16) followed by the page number of the paper in the corresponding Proceedings. The author index lists each author who has participated in the air cleaning conferences over the years, and the paper index lists all authors of the respective papers. The KWIC index is, in effect, a comprehensive subject cross index; each paper is listed as many times, by keyword, as there are major terms (i.e., keywords) in its title. Although this multiple listing results in a lengthy list, it provides a very deep cross-indexing of the papers

  7. Index

    OpenAIRE

    Editörden .

    2014-01-01

    ed and indexed in Copernicus, Index Google Scholarship, the PSCR, DOAJ, Research Bible, Indian Open Access Journals (OAJ), Institutional Repositories (IR), Journal TOCs, J-Gate (Informatics India), Ulrich’s, ResearchGate, International Society of Universal Research in Sciences, DRJI, EyeSource

  8. Index

    OpenAIRE

    Editörden .

    2013-01-01

    ed and indexed in Copernicus, Index Google Scholarship, the PSCR, DOAJ, Research Bible, Indian Open Access Journals (OAJ), Institutional Repositories (IR), Journal TOCs, J-Gate (Informatics India), Ulrich’s, ResearchGate, International Society of Universal Research in Sciences, DRJI, EyeSource

  9. Extremely high-accuracy correction of air refractive index using two-colour optical frequency combs.

    Science.gov (United States)

    Wu, Guanhao; Takahashi, Mayumi; Arai, Kaoru; Inaba, Hajime; Minoshima, Kaoru

    2013-01-01

    Optical frequency combs have become an essential tool for distance metrology, showing great advantages compared with traditional laser interferometry. However, there is not yet an appropriate method for air refractive index correction to ensure the high performance of such techniques when they are applied in air. In this study, we developed a novel heterodyne interferometry technique based on two-colour frequency combs for air refractive index correction. In continuous 500-second tests, a stability of 1.0 × 10(-11) was achieved in the measurement of the difference in the optical distance between two wavelengths. Furthermore, the measurement results and the calculations are in nearly perfect agreement, with a standard deviation of 3.8 × 10(-11) throughout the 10-hour period. The final two-colour correction of the refractive index of air over a path length of 61 m was demonstrated to exhibit an uncertainty better than 1.4 × 10(-8), which is the best result ever reported without precise knowledge of environmental parameters. PMID:23719387

  10. The Air Connectivity Index : Measuring Integration in the Global Air Transport Network

    OpenAIRE

    Arvis, Jean-François; Shepherd, Ben

    2011-01-01

    The authors construct a new measure of connectivity in the global air transport network, covering 211 countries and territories for the year 2007. It is grounded in network analysis methods, and is based on a gravity-like model that is familiar from the international trade and regional science literatures. It is a global measure of connectivity, in the sense that it captures the full range...

  11. Effects of Age, Gender and Body Mass Index on Reaction to Air Condition

    OpenAIRE

    Nkwam C. Uwaoma; Anthony Nkwocha

    2011-01-01

    Abstract: This study investigated the effect of age, gender, and body mass index (BMI) on reaction to air condition. Forty eight undergraduates (21 males and 27 females) randomly selected from Imo State University, Owerri, Nigeria within the age range of 17-30 years participated in the study. 26 of them were of normal weight (BMI 24). They were exposed to an air conditioned room for two hours and then their reaction to cold measured using Response to Cold questionnaire. Employing t-test and A...

  12. Compressed Air Energy Storage System Control and Performance Assessment Using Energy Harvested Index

    OpenAIRE

    Hanif SedighNejad; Tariq Iqbal; John Quaicoe

    2014-01-01

    In this paper a new concept for control and performance assessment of compressed air energy storage (CAES) systems in a hybrid energy system is introduced. The proposed criterion, based on the concept of energy harvest index (HEI), measures the capability of a storage system to capture renewable energy. The overall efficiency of the CAES system and optimum control and design from the technical and economic point of view is presented. A possible application of this idea is an isolated communit...

  13. Suppression of Air Refractive Index Variations in High-Resolution Interferometry

    OpenAIRE

    Zden?k Buchta; Jan Hrabina; Martin ?ížek; Ond?ej ?íp; Josef Lazar

    2011-01-01

    The influence of the refractive index of air has proven to be a major problem on the road to improvement of the uncertainty in interferometric displacement measurements. We propose an approach with two counter-measuring interferometers acting as a combination of tracking refractometer and a displacement interferometer referencing the wavelength of the laser source to a mechanical standard made of a material with ultra-low thermal expansion. This technique combines length measurement within a ...

  14. Analysis and evolution of air quality monitoring networks using combined statistical information indexes

    Directory of Open Access Journals (Sweden)

    Axel Osses

    2013-10-01

    Full Text Available In this work, we present combined statistical indexes for evaluating air quality monitoring networks based on concepts derived from the information theory and Kullback–Liebler divergence. More precisely, we introduce: (1 the standard measure of complementary mutual information or ‘specificity’ index; (2 a new measure of information gain or ‘representativity’ index; (3 the information gaps associated with the evolution of a network and (4 the normalised information distance used in clustering analysis. All these information concepts are illustrated by applying them to 14 yr of data collected by the air quality monitoring network in Santiago de Chile (33.5 S, 70.5 W, 500 m a.s.l.. We find that downtown stations, located in a relatively flat area of the Santiago basin, generally show high ‘representativity’ and low ‘specificity’, whereas the contrary is found for a station located in a canyon to the east of the basin, consistently with known emission and circulation patterns of Santiago. We also show interesting applications of information gain to the analysis of the evolution of a network, where the choice of background information is also discussed, and of mutual information distance to the classifications of stations. Our analyses show that information as those presented here should of course be used in a complementary way when addressing the analysis of an air quality network for planning and evaluation purposes.

  15. Tolerance Levels of Roadside Trees to Air Pollutants Based on Relative Growth Rate and Air Pollution Tolerance Index

    Directory of Open Access Journals (Sweden)

    SULISTIJORINI

    2008-09-01

    Full Text Available Motor vehicles release carbon monoxide, nitrogen dioxide, sulphur dioxide, and particulate matters to the air as pollutants. Vegetation can absorb these pollutants through gas exchange processes. The objective of this study was to examine the combination of the relative growth rate (RGR and physiological responses in determining tolerance levels of plant species to air pollutants. Physiological responses were calculated as air pollution tolerance index (APTI. Eight roadside tree species were placed at polluted (Jagorawi highway and unpolluted (Sindangbarang field area. Growth and physiological parameters of the trees were recorded, including plant height, leaf area, total ascorbate, total chlorophyll, leaf-extract pH, and relative water content. Scoring criteria for the combination of RGR and APTI method was given based on means of the two areas based on two-sample t test. Based on the total score of RGR and APTI, Lagerstroemia speciosa was categorized as a tolerant species; and Pterocarpus indicus, Delonix regia, Swietenia macrophylla were categorized as moderately tolerant species. Gmelina arborea, Cinnamomum burmanii, and Mimusops elengi were categorized as intermediate tolerant species. Lagerstroemia speciosa could be potentially used as roadside tree. The combination of RGR and APTI value was better to determinate tolerance level of plant to air pollutant than merely APTI method.

  16. Air trapping on computed tomography images of healthy individuals: effects of respiration and body mass index

    Energy Technology Data Exchange (ETDEWEB)

    Hashimoto, M.; Tate, E.; Watarai, J.; Sasaki, M

    2006-10-15

    Aim: To evaluate the relationships of changes in the lung area during respiration and of individual body mass index (BMI) to air trapping on expiratory computed tomography (CT) in young non-smoking adults of either gender. Methods: The volunteers were 10 women and 10 men (mean age 25.7 years) who were healthy lifelong non-smokers. We obtained both end-inspiratory and end-expiratory CT images at three levels: the upper, middle and lower lung. The ratio of cross-sectional lung area upon expiration to cross-sectional lung area upon inspiration (lung area ratio) was determined for each lung at each of the three levels. In cases showing air trapping, we calculated the percentage of area of air in relation to the total lung area in each section. BMI was calculated for each participant. Results: Air trapping was present in dependent areas of the lungs of 6 women and 5 men. The mean percentage of area of air trapped was statistically greater for men (9.8 {+-} 9.2%) than for women (4.9 {+-} 5.2%). The mean lung area ratio was 0.52 {+-} 0 14 among volunteers with air trapping (66 sections) and 0.69 {+-} 0.12 among those without air trapping (54 sections) (p < 0.001). At each lung level, the mean lung area ratio was greater in individuals with air trapping than in those without. Mean BMI was also greater in these people (p = 0.009). Conclusion: Change in the respiratory lung area and BMI contribute to development of air trapping.

  17. Air trapping on computed tomography images of healthy individuals: effects of respiration and body mass index

    International Nuclear Information System (INIS)

    Aim: To evaluate the relationships of changes in the lung area during respiration and of individual body mass index (BMI) to air trapping on expiratory computed tomography (CT) in young non-smoking adults of either gender. Methods: The volunteers were 10 women and 10 men (mean age 25.7 years) who were healthy lifelong non-smokers. We obtained both end-inspiratory and end-expiratory CT images at three levels: the upper, middle and lower lung. The ratio of cross-sectional lung area upon expiration to cross-sectional lung area upon inspiration (lung area ratio) was determined for each lung at each of the three levels. In cases showing air trapping, we calculated the percentage of area of air in relation to the total lung area in each section. BMI was calculated for each participant. Results: Air trapping was present in dependent areas of the lungs of 6 women and 5 men. The mean percentage of area of air trapped was statistically greater for men (9.8 ± 9.2%) than for women (4.9 ± 5.2%). The mean lung area ratio was 0.52 ± 0 14 among volunteers with air trapping (66 sections) and 0.69 ± 0.12 among those without air trapping (54 sections) (p < 0.001). At each lung level, the mean lung area ratio was greater in individuals with air trapping than in those without. Mean BMI was also greater in these people (p = 0.009). Conclusion: Change in the respiratory lung area and BMI contribute to development of air trapping

  18. Comparison of the Revised Air Quality Index with the PSI and AQI indices

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Wan-Li; Chen, Yu-Song; Chang, Shiang-Hung [Dept of Environmental Science and Engineering, Tunghai University, Taichung 407 (China); Zhang, Junfeng [Division of Environmental and Occupational Health, University of Medicine and Dentistry of New Jersey, NJ 08854 (United States); Lyons, T.J. [Environmental Science, Murdoch University, Murdoch, WA 6150 (Australia); Pai, Joy-Lynn [Sunway Environmental Technology Co., Ltd., Taipei 104 (China)

    2007-09-01

    Air pollution indices are commonly used to indicate the level of severity of air pollution to the public. The Pollution Standards Index (PSI) was initially established in response to a dramatic increase in the number of people suffering respiratory irritation due to the deteriorating air quality. The PSI was subsequently revised and implemented by the USEPA in 1999, and became known as the Air Quality Index (AQI) that includes data relating to particle suspension, PM{sub 2.5}, and a selective options of either 8-hour or 1-hour ozone concentration during increased O{sub 3} periods. Yet, the costs of launching a network of PM{sub 2.5} monitoring stations are prohibitively high for many countries to implement the AQI from the PSI system in the foreseeable future. Therefore, the purpose of this research is to discuss the optimal method of assessing air quality using the latest developed Revised AQI (RAQI), a system that serves as an alternative to the PSI and AQI systems. The feasibility, effectiveness, and the differences between RAQI, AQI, and PSI in their applications to several air pollution conditions are also studied in this research. The results show that southern Taiwan's suspended particulates have significantly greater impact on PM{sub 2.5}/PM{sub 10} ratios than in central and northern metropolitan areas, and that the ratios are higher in Taiwan as a whole compared to many other countries. We also found that the RAQI shows more significant results compared to the PSI and AQI as it has a wider coverage of the range of pollutant concentration levels. (author)

  19. Using Social Media to Detect Outdoor Air Pollution and Monitor Air Quality Index (AQI): A Geo-Targeted Spatiotemporal Analysis Framework with Sina Weibo (Chinese Twitter)

    OpenAIRE

    Jiang, Wei; Wang, Yandong; Tsou, Ming-Hsiang; Fu, Xiaokang

    2015-01-01

    Outdoor air pollution is a serious problem in many developing countries today. This study focuses on monitoring the dynamic changes of air quality effectively in large cities by analyzing the spatiotemporal trends in geo-targeted social media messages with comprehensive big data filtering procedures. We introduce a new social media analytic framework to (1) investigate the relationship between air pollution topics posted in Sina Weibo (Chinese Twitter) and the daily Air Quality Index (AQI) pu...

  20. Indexed

    CERN Document Server

    Hagy, Jessica

    2008-01-01

    Jessica Hagy is a different kind of thinker. She has an astonishing talent for visualizing relationships, capturing in pictures what is difficult for most of us to express in words. At indexed.blogspot.com, she posts charts, graphs, and Venn diagrams drawn on index cards that reveal in a simple and intuitive way the large and small truths of modern life. Praised throughout the blogosphere as “brilliant,” “incredibly creative,” and “comic genius,” Jessica turns her incisive, deadpan sense of humor on everything from office politics to relationships to religion. With new material along with some of Jessica’s greatest hits, this utterly unique book will thrill readers who demand humor that makes them both laugh and think.

  1. Air index compensated interferometer as a prospective novel primary standard for baseline calibrations

    Science.gov (United States)

    Meiners-Hagen, Karl; Bošnjakovic, Alen; Köchert, Paul; Pollinger, Florian

    2015-08-01

    We describe the status of the development of an interferometer for absolute distance measurements with an intrinsic compensation of the refractive index of air, intended as a primary standard for the calibration of geodetic baselines. Two frequency-doubled Nd:YAG lasers are offset locked with a frequency difference of ?20 GHz at the infrared 1064 nm fundamental wavelength. The resulting synthetic wavelengths of 15 mm for the infrared and 7.5 mm for the frequency-doubled green light are used as the scale for the measurements. Longer synthetic wavelengths are generated by acousto-optic frequency shifters. Based on the dispersion in air between green and infrared light the refractive index can be compensated. The attempt is demanding since uncertainties of the interferometric measurements for the optical wavelengths are scaled by a factor of nearly 300?000 in the refractive index compensated result. First comparisons up to 50 m length between this interferometer and a HeNe reference are presented. The deviations are smaller than ± 200 µm and dominated by a non-linearity from problems in the collimation of the measurement beams. In the linear parts the deviations are below ± 100 µm.

  2. Measurement of air refractive index fluctuation based on interferometry with two different reference cavity lengths.

    Science.gov (United States)

    Chen, Qianghua; Luo, Huifu; Wang, Sumei; Wang, Feng; Chen, Xinhua

    2012-09-01

    A measurement method based on interferometry with two different reference cavity lengths is presented and applied in air refractive index measurement in which the two cavity lengths and a laser wavelength are combined to generate two wavelength equivalents of cavity. Corresponding calculation equations are derived, and the optical path configuration is designed, which is inspired by the traditional synthetic wavelength method. Theoretical analyses indicate that the measurement uncertainty of the determined index of refraction is about 2.3×10(-8), which is mainly affected by the length precision of the long vacuum cavity and the ellipticity of polarization components of the dual-frequency laser, and the range of nonambiguity is 3.0×10(-5), which is decided by the length difference of the two cavities. Experiment results show that the accuracy of air refractive index measurement is better than 5.0×10(-8) when the laboratory conditions changes slowly. The merit of the presented method is that the classical refractometry can be also used without evacuation of the gas cavity during the experiment. Furthermore, the application of the traditional synthetic wavelength method may be extended by using the wavelength equivalents of cavity, any value of which can be easily acquired by changing cavity length rather than using actual wavelengths whose number is limited. PMID:22945157

  3. The air quality health index and emergency department visits for urticaria in Windsor, Canada.

    Science.gov (United States)

    Kousha, Termeh; Valacchi, Giuseppe

    2015-01-01

    Ambient air pollution exposure has been associated with several health conditions, limited not only to respiratory and cardiovascular systems but also to cutaneous tissues. However, few epidemiological studies examined pollution exposure on skin problems. Basically, the common mechanism by which pollution may affect skin physiology is by induction of oxidative stress and inflammation. Urticaria is among the skin pathologies that have been associated with pollution. Based on the combined effects of three ambient air pollutants, ozone (O?), nitrogen dioxide (NO?), and fine particulate matter (PM) with a median aerodynamic diameter of less than 2.5 ?m (PM(2.5)), on mortality, the Air Quality Health Index (AQHI) in Canada was developed. The aim of this study was to examine the associations of short-term changes in AQHI with emergency department (ED) visits for urticaria in Windsor-area hospitals in Canada. Diagnosed ED visits were retrieved from the National Ambulatory Care Reporting System (NACRS). A time-stratified case-crossover design was applied to 2905 ED visits (males = 1215; females = 1690) for urticaria from April 2004 through December 2010. Odds ratios (OR) and their corresponding 95% confidence intervals (95%CI) for ED visits associated with increase by one unit of risk index were calculated employing conditional logistic regression. Positive and significant results were observed between AQHI levels and OR for ED visits for urticaria in Windsor for lags 2 and 3 days. A distributed lag nonlinear model technique was applied to daily counts of ED visits for lags 0 to 10 and significant results were obtained from lag 2 to lag 5 and for lag 9. These findings demonstrated associations between ambient air pollution and urticarial confirming that air pollution affects skin conditions. PMID:25849769

  4. Preparation and determination of kerma for Iridium 192 sources of low dose rate for brachytherapy; Preparacion y determinacion del kerma de fuentes de iridio-192 de baja tasa de dosis para braquiterapia

    Energy Technology Data Exchange (ETDEWEB)

    Tendilla, J.I.; Tovar M, V.; Mitsoura, E.; Aguilar H, F.; Alanis M, J. [Instituto Nacional de Investigaciones Nucleares, C.P. 52045-1, Salazar, Esrado de Mexico, D.F. (Mexico)

    2000-07-01

    The practice of Brachytherapy with Iridium-192 sources of low dose rate (0.4 - 0.8 Gy/h) is a technique used in the treatment of diverse illnesses. in this work the preparation, quality control and calibration are presented in terms of kerma in air of Iridium-192 using as target these recycled Iridium-Platinum wires. The targets were obtained as decayed sources of different radio therapeutical centers in the country and they were characterized by Scanning electron microscopy in order to determine their chemical composition. Subsequently it was developed an experimental design to establish the effect of neutron flux, geometrical array and irradiation time over the activity and percentage of the sources homogeneity. The homogeneity was determined by auto radiography and by Gamma spectroscopy. Once the optimal irradiation conditions were established, it is determined the apparent activity and kerma in air using a well type ionization chamber with traceability to a primary laboratory. Iridium-192 sources were obtained with an average homogeneity 96 %, apparent activity 282.129 {+-} 0.531 M Bq and kerma in air 0.03200 {+-} 0.00006 m Gy m/h A. (Author)

  5. Compressed Air Energy Storage System Control and Performance Assessment Using Energy Harvested Index

    Directory of Open Access Journals (Sweden)

    Hanif SedighNejad

    2014-01-01

    Full Text Available In this paper a new concept for control and performance assessment of compressed air energy storage (CAES systems in a hybrid energy system is introduced. The proposed criterion, based on the concept of energy harvest index (HEI, measures the capability of a storage system to capture renewable energy. The overall efficiency of the CAES system and optimum control and design from the technical and economic point of view is presented. A possible application of this idea is an isolated community with significant wind energy resource. A case study reveals the usefulness of the proposed criterion in design, control and implementation of a small CAES system in a hybrid power system (HPM for an isolated community. Energy harvested index and its effectiveness in increasing the wind penetration rate in the total energy production is discussed.

  6. Estimation of the refractive index structure characteristic of air from coherent Doppler wind lidar data.

    Science.gov (United States)

    Banakh, V A; Smalikho, I N; Rahm, S

    2014-08-01

    A technique is proposed for estimating the refractive index structure characteristic of air from data of a coherent Doppler wind lidar. The proposed technique is tested in atmospheric experiments. Time profiles of the structure characteristic in the atmospheric surface layer are obtained and compared with the time profiles of the dissipation rate of the kinetic energy of turbulence obtained from the same lidar data. It is shown in this way that coherent lidars can be used for investigating not only wind turbulence, but also temperature turbulence. PMID:25078167

  7. Air-trench splitters for ultra-compact ring resonators in low refractive index contrast waveguides.

    Science.gov (United States)

    Rahmanian, Nazli; Kim, Seunghyun; Lin, Yongbin; Nordin, Gregory P

    2008-01-01

    We demonstrate air-trench splitters in low index contrast perfluorocyclobutyl (PFCB) waveguides. Splitters are fabricated by etching 800 nm wide high aspect ratio (18:1) trenches. The measured optical loss is 0.4 dB/splitter. The reflection/transmission splitting ratio is 0.859/0.141, which closely matches two-dimensional finite difference time domain (2DFDTD) simulation results. Air-trench splitters and bends are used to demonstrate an ultra-compact ring resonator (RR) with a size reduction of 1,700 compared to a RR based on traditional curved waveguides in the same material system. A comparison between the RR's measured and analytically calculated performance shows close agreement when splitter and bend losses are taken into account. PMID:18521178

  8. Competency Index for Air Conditioning and Refrigeration Programs in Missouri. A Crosswalk of Selected Instructional Materials against Missouri's Competency Profile.

    Science.gov (United States)

    Missouri Univ., Columbia. Instructional Materials Lab.

    This index was developed to help air conditioning and refrigeration instructors in Missouri use existing instructional materials and keep track of student progress on the VAMS system. The list was compiled by a committee of instructors who selected appropriate references and identified areas that pertained to Missouri competencies. The index lists…

  9. Comparison of TLD air kerma measurements in mammography

    International Nuclear Information System (INIS)

    The mammography examination is usually targeted at asymptomatic women so the narrow balance between benefit and undesirable effects is important. During the past few decades there have been significant advances in the equipment used for mammography. Even when the latest equipment and imaging systems are used, there is considerable variation from centre-to-centre in the choice of imaging parameters and techniques. There may be quite large differences in image quality and breast dose among the centres. A Co-ordinated Research Programme on 'Image quality and patient dose optimization in mammography in Eastern European Countries' was conducted by the IAEA, aiming at defining a methodology for the implementation of a quality assurance (QA) programme in mammography and at exercising the assessment of image quality and patient doses in a sample of hospitals in East European countries. Selected mammography clinics from Czech Republic, Hungary, Poland, Romania and Slovakia participate in the project. The teams consisted of experienced clinicians and physicists. They were supported by a group of experts (clinicians and medical physicists) from France, Italy and Spain. As an outcome of the project, improvements in these indicators (image quality and patient dose) after the implementation of the QA programme are expected. A comparison of dosimetry systems has been organized to assure that dosimetry measurements done in the frame of the project are comparable and traceable to the international measurement system. All five East European countries plus Spain took part in the exercise. The thermoluminescent (TL) method was selected for the comparison

  10. Fundamental relationships between linear energy transfer, absorbed dose, kerma, and exposure. Application to changes of mediums

    International Nuclear Information System (INIS)

    After briefly defining the quantities used in dosimetry and presenting them with a view to their simple adaptation to health physics problems, the authors establish simple mathematical relationships to express the absorbed dose, kerma and exposure in the case of electrons and photons, and also relationships between these various quantities considered in air. They then proceed to study the variations in these quantities at the interface between the air and the soft tissues of the organism and in depth in the tissues. They give the numerical values of the discontinuities liable to appear at the interface and the values obtained, relative to air, after electronic equilibrium is established in depth in the tissues. An example of application to dosimetry is also given in the case of an aluminium-walled ionization chamber. To conclude, the conditions to be fulfilled in order to make a direct measurement of the absorbed dose in the tissues are presented and discussed. (authors)

  11. Impacts of Air Pollution on Productivity Growth in the Air and Truck Transportation Industries in the US: an Application of the Data Envelopment Analysis Malmquist Environmental Productivity Index

    OpenAIRE

    Jaesung Choi; Roberts, David C.

    2015-01-01

    Air pollution worsens work environment and increases the likelihood of health risks and even premature death for humans. Owing to the fundamental structure of growth through the combustion of fossil fuels, productivity growth in the transportation industry has affected the natural environment. In this study, the authors use the Malmquist environmental productivity index to consider the effects of air pollution on productivity growth in the air and truck transportation industries, which are th...

  12. CHANGE ON SPEED AIR CHARACTERISTICS THE POWER INDICATOR INDEXES OF PNEUMATIC ENGINE WITHOUT HEATING THE CHARGE DURING THE ADMITTANCE

    Directory of Open Access Journals (Sweden)

    A. Voronkov

    2014-10-01

    Full Text Available The experimental data on change according to speed characteristics of power indicator indexes of the four cylinder pneumatic engine D/S = 76/66 with a slide-valve air distributor at unchangeable temperature of compressed input air is considered.

  13. Evaluation of air pollution tolerance index of selected plant species along roadsides in Thiruvananthapuram, Kerala.

    Science.gov (United States)

    Jyothi, S Jissy; Jaya, D S

    2010-05-01

    To develop the usefulness of plants as bioindicators requires an appropriate selection of plant species which entail an utmost importance for a particular situation. In the present study a periodic evaluation of air pollution tolerance index [APTI] of selected tree species such as Polyalthia longifolia, (Sonner) Thw., Alstonia scholaris, R. Br., Mangifera indica, L., and shrubs Clerodendron infortunatum, L., Eupatorium odoratum, L., and Hyptis suaveolens, (L.) Poit., growing adjacent to the National Highway-47 passing through Thiruvananthapuram District which lies on the south-west coast of India, was carried out with a view to find out the air pollution tolerance as well as sensitivity of the plant species during different seasons. Among the trees in the roadside areas studied, Polyalthia longifolia, (Sonner) Thw., expressed highest APTI values and proved to be a tolerant variety and the others as sensitive species to air pollutants. In the case of shrubs, Clerodendron infortunatum, L., exhibited highest APTI values (7.34) and found to be more tolerant compared to the other two shrub species studied. PMID:21047015

  14. Radioactive Aerosols as an Index of Air Pollution in the City of Thessaloniki, Greece

    International Nuclear Information System (INIS)

    This study summarizes results of an investigation done in order to find out how the radioactive aerosols of 7Be could serve as indicators of air pollution conditions. Beryllium-7 is a cosmic-ray produced radionuclide with an important fraction of its production to take place in the upper troposphere. Once it is formed is rapidly associated with submicron aerosol particles and participates in the formation and growth of the accumulation mode aerosols, which is a major reservoir of pollutants in the atmosphere. In order to define any influence of AMAD of 7Be aerosols by air pollution conditions, the aerodynamic size distribution of 7Be aerosols was determined by collecting samples at different locations in the suburban area of the city of Thessaloniki, including rural areas, industrial areas, high elevations, marine environment and the airport area. The aerodynamic size distribution of 7Be aerosols in different locations was obtained by using Andersen 1-ACFM cascade impactors and the Activity Median Aerodynamic Diameter (AMAD) was determined. Some dependency of the AMADs on height has been observed, while in near marine environment the 7Be activity size distribution was dominant in the upper size range of aerosol particles. Low AMADs as low as 0.62 to 0.74 μm of 7Be aerosols have been observed at locations characterized with relative low pollution, while it is concluded that in the activity size distribution of ambient aerosols, 7Be changes to larger particle sizes in the presence of pollutants, since low AMADs of 7Be aerosols have been observed at low polluted locations. Preliminary data of simultaneous measurements of 214Pb and 212Pb with gaseous air pollutants CO, NO, NOX, SO2 and total suspended particulate matter (TSP) show that radon decay products near the ground could be a useful index of air pollution potential conditions and transport processes in the boundary layer.

  15. Using Social Media to Detect Outdoor Air Pollution and Monitor Air Quality Index (AQI): A Geo-Targeted Spatiotemporal Analysis Framework with Sina Weibo (Chinese Twitter).

    Science.gov (United States)

    Jiang, Wei; Wang, Yandong; Tsou, Ming-Hsiang; Fu, Xiaokang

    2015-01-01

    Outdoor air pollution is a serious problem in many developing countries today. This study focuses on monitoring the dynamic changes of air quality effectively in large cities by analyzing the spatiotemporal trends in geo-targeted social media messages with comprehensive big data filtering procedures. We introduce a new social media analytic framework to (1) investigate the relationship between air pollution topics posted in Sina Weibo (Chinese Twitter) and the daily Air Quality Index (AQI) published by China's Ministry of Environmental Protection; and (2) monitor the dynamics of air quality index by using social media messages. Correlation analysis was used to compare the connections between discussion trends in social media messages and the temporal changes in the AQI during 2012. We categorized relevant messages into three types, retweets, mobile app messages, and original individual messages finding that original individual messages had the highest correlation to the Air Quality Index. Based on this correlation analysis, individual messages were used to monitor the AQI in 2013. Our study indicates that the filtered social media messages are strongly correlated to the AQI and can be used to monitor the air quality dynamics to some extent. PMID:26505756

  16. Using Social Media to Detect Outdoor Air Pollution and Monitor Air Quality Index (AQI): A Geo-Targeted Spatiotemporal Analysis Framework with Sina Weibo (Chinese Twitter)

    Science.gov (United States)

    Tsou, Ming-Hsiang; Fu, Xiaokang

    2015-01-01

    Outdoor air pollution is a serious problem in many developing countries today. This study focuses on monitoring the dynamic changes of air quality effectively in large cities by analyzing the spatiotemporal trends in geo-targeted social media messages with comprehensive big data filtering procedures. We introduce a new social media analytic framework to (1) investigate the relationship between air pollution topics posted in Sina Weibo (Chinese Twitter) and the daily Air Quality Index (AQI) published by China’s Ministry of Environmental Protection; and (2) monitor the dynamics of air quality index by using social media messages. Correlation analysis was used to compare the connections between discussion trends in social media messages and the temporal changes in the AQI during 2012. We categorized relevant messages into three types, retweets, mobile app messages, and original individual messages finding that original individual messages had the highest correlation to the Air Quality Index. Based on this correlation analysis, individual messages were used to monitor the AQI in 2013. Our study indicates that the filtered social media messages are strongly correlated to the AQI and can be used to monitor the air quality dynamics to some extent. PMID:26505756

  17. Calibration of Kerma Area Product Meters with a Patient Dose Calibrator

    International Nuclear Information System (INIS)

    Kerma area product (KAP) meters used in X ray imaging for monitoring patient exposure were calibrated using different reference meters. Typically, the reference KAP value is the product of the air kerma and the X ray field size. In the tandem method, the reference value is measured with another KAP meter; in this study, a large KAP meter of novel type, the patient dose calibrator (PDC), was used for this purpose. The properties of the PDC meter were studied and the use of the meter as a reference meter was reviewed throughout the whole train of events from calibration in a secondary standard dosimetry laboratory to using the meter in clinical situations. Compared to conventional KAP meters, the advantages of the PDC are the lower energy dependence of response and the possibility to use larger field sizes. In laboratory measurements, the properties of the PDC meter were proved suitable to be used as a reference meter. The uncertainty related to the differences in X ray tube output used in calibration at the laboratory and in measurements at the clinic is highlighted. The calibration coefficients for field KAP meters calibrated by the PDC meter and by other meters were congruent on the average within 4%. Clinical measurements emphasized the need for in situ calibration of clinical KAP meters. Particularly in the under-couch situation, the calibration should be performed with the couch in the beam. (author)

  18. Assessment of air pollution tolerance index of some trees in Moradabad city, India.

    Science.gov (United States)

    Tripathi, Anamika; Tiwari, P B; Mahima; Singh, Dharmveer

    2009-07-01

    To see the relative tolerance of the plant species, ten different plant species i.e. Ficus rumphii, Pongamia pinnata, Alstonia scholaris, Holoptelea integrifolia, Saraca indica, Pithecolobium dulcis, Cassia simea, Bauhinia variegata, Azadirachta indica and Grewelia robusta was taken from residential (SI), industrial (SII) and commercial (SIII) area of the city as this florais very much common to the Brass city and is planted on the roadside. The quality of air with respect to SPM, SO2 and NO2 has been also assessed on respective sites to see its effect on biochemical parameters of the leaves i.e. pH, total water content, chlorophyll and ascorbic acid and evaluate the (air pollution tolerance index (APTI) of various plants. It was concluded that Pongamia pinnata 15.8, Pithecolobium dulcis 34.8, Holoptelea integrifolia 55.8 and Saraca indica 52.0 have very high APTI value over control so these are considered as high tolerant tree species, Ficus rumphii 35.7, Azadirachta indica 30.5 and Grewelia robusta 34.3 have slightlymoreAPTI value over control so these are considered as moderately tolerant tree species and Alstonia scholaris 21.5, Cassia simea 6.09 and Bauhinia variegata 18.22 have lessAPTI value than control, so these are sensitive species respectively. One way ANOVA finds the obtained values to be highly significant (p < 0.001) at the industrial site. Thus present findings show that Brass and allied industries are the prominent sources responsible for the elevated level of air pollutants at the industrial site. PMID:20120494

  19. Development of a calibration methodology and tests of kerma area product meters; Desenvolvimento de uma metodologia de calibracao e testes de medidores de produto Kerma-Area

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Nathalia Almeida

    2013-07-01

    The quantity kerma area product (PKA) is important to establish reference levels in diagnostic radiology exams. This quantity can be obtained using a PKA meter. The use of such meters is essential to evaluate the radiation dose in radiological procedures and is a good indicator to make sure that the dose limit to the patient's skin doesn't exceed. Sometimes, these meters come fixed to X radiation equipment, which makes its calibration difficult. In this work, it was developed a methodology for calibration of PKA meters. The instrument used for this purpose was the Patient Dose Calibrator (PDC). It was developed to be used as a reference to check the calibration of PKA and air kerma meters that are used for dosimetry in patients and to verify the consistency and behavior of systems of automatic exposure control. Because it is a new equipment, which, in Brazil, is not yet used as reference equipment for calibration, it was also performed the quality control of this equipment with characterization tests, the calibration and an evaluation of the energy dependence. After the tests, it was proved that the PDC can be used as a reference instrument and that the calibration must be performed in situ, so that the characteristics of each X-ray equipment, where the PKA meters are used, are considered. The calibration was then performed with portable PKA meters and in an interventional radiology equipment that has a PKA meter fixed. The results were good and it was proved the need for calibration of these meters and the importance of in situ calibration with a reference meter. (author)

  20. Air cavity-based Fabry-Perot interferometer sensor fabricated using a sawing technique for refractive index measurement

    Science.gov (United States)

    Jung, Eun Joo; Lee, Woo-Jin; Kim, Myoung Jin; Hwang, Sung Hwan; Rho, Byung Sup

    2014-01-01

    We have demonstrated a refractive index sensor based on a fiber optic Fabry-Perot (FP) interferometer with an open air cavity fabricated using a one-step mechanical sawing technique. The sensor head consists of a short FP cavity near the fiber patch cord tip, which was assembled by joining a ceramic ferrule and a single-mode fiber together. Owing to the open air cavity in the sensor head, various liquid samples with different refractive index can fill in-line air cavity, which makes the device usable as a refractometer. Moreover, due to the sensor head encircled with the robust ceramic ferrule, the device is attractive for sensing measurement in harsh environments. The sensor was tested in different refractive index solutions. The experimental result shows that the attenuation peak wavelength of the sensor is shifted toward a shorter wavelength with increasing refractive index, and the refractive index sensitivity is ˜92.5 nm/refractive index unit (RIU) and 73.75 dB/RIU. The proposed sensor can be used as an in-line refractometer for many potential applications in the sensing field.

  1. Speed and kerma requirements of film-foil combinations

    International Nuclear Information System (INIS)

    The duties of the manufacturer are defined in section 16 X-Ray Ordinance. They refer to the speed of the combination (DIN 6867, part 1), the resolving power limit, gradation of the film, spectral sensitivity, and optical spectrum of the intensifying foil. The connection between speed and kerma is discussed in this article, and the question of whether the speed of the film-foil combination gives any information on the image quality to be expected. (DG)

  2. Estimation of Anticipated Performance Index and Air Pollution Tolerance Index and of vegetation around the marble industrial areas of Potwar region: bioindicators of plant pollution response.

    Science.gov (United States)

    Noor, Mehwish Jamil; Sultana, Shazia; Fatima, Sonia; Ahmad, Mushtaq; Zafar, Muhammad; Sarfraz, Maliha; Balkhyour, Masour A; Safi, Sher Zaman; Ashraf, Muhammad Aqeel

    2015-06-01

    Mitigating industrial air pollution is a big challenge, in such scenario screening of plants as a bio monitor is extremely significant. It requires proper selection and screening of sensitive and tolerant plant species which are bio indicator and sink for air pollution. The present study was designed to evaluate the Air Pollution Tolerance Index (APTI) and Anticipated Performance Index (API) of the common flora. Fifteen common plant species from among trees, herb and shrubs i.e. Chenopodium album (Chenopodiaceae), Parthenium hysterophorus (Asteraceae), Amaranthus viridis (Amaranthaceae), Lantana camara (Verbenaceaea), Ziziphus nummulari (Rhamnaceae), Silibum merianum (Asteraceae), Cannabis sativa (Cannabinaceae), Calatropis procera (Asclepediaceae), Ricinus communis (Euphorbiaceae), Melia azadirachta (Meliaceae), Psidium guajava (Myrtaceae), Eucalyptus globules (Myrtaceae), Broussonetia papyrifera (Moraceae), Withania somnifera (Solanaceae) and Sapium sabiferum (Euphorbiaceae) were selected growing frequently in vicinity of Marble industries in Potwar region. APTI and API of selected plant species were analyzed by determining important biochemical parameter i.e. total chlorophyll, ascorbic acid, relative water content and pH etc. Furthermore the selected vegetation was studied for physiological, economic, morphological and biological characteristics. The soil of studied sites was analyzed. It was found that most the selected plant species are sensitive to air pollution. However B. papyrifera, E. globulus and R. communis shows the highest API and therefore recommended for plantation in marble dust pollution stress area. PMID:25503327

  3. Applicability of the Environmental Relative Moldiness Index for Quantification of Residential Mold Contamination in an Air Pollution Health Effects Study

    OpenAIRE

    Ali Kamal; Janet Burke; Stephen Vesper; Stuart Batterman; Alan Vette; Christopher Godwin; Marina Chavez-Camarena; Gary Norris

    2014-01-01

    The Near-Road Exposures and Effects of Urban Air Pollutants Study (NEXUS) investigated the impact of exposure to traffic-related air pollution on the respiratory health of asthmatic children in Detroit, Michigan. Since indoor mold exposure may also contribute to asthma, floor dust samples were collected in participants homes (n = 112) to assess mold contamination using the Environmental Relative Moldiness Index (ERMI). The repeatability of the ERMI over time, as well as ERMI differences betwe...

  4. Review of Kerma-Area Product and total energy incident on patients in radiography, mammography and CT.

    Science.gov (United States)

    Yao, Hai; Huda, Walter; Mah, Eugene; He, Wenjun

    2015-02-01

    This study estimated the energy incident on patients in radiography, mammography and CT using data related to X-ray beam quantity and quality. The total X-ray beam quantity is the average Air Kerma multiplied by the X-ray beam area and expressed as the Kerma-Area Product (Gy cm(-2)). The X-ray beam quality primarily depends on the target material (and anode angle), X-ray voltage (and ripple) as well as X-ray beam filtration. For any X-ray spectra, dividing total energy (fluence × mean energy) by the X-ray beam Kerma-Area Product yields the energy per Kerma-Area Product value (?/KAP). Published data on X-ray spectra characteristics and energy fluence per Air Kerma conversion factors were used to determine ?/KAP factors. In radiography, ?/KAP increased from 6 mJ Gy(-1) cm(-2) at the lowest X-ray tube voltage (50 kV) to 25 mJ Gy(-1) cm(-2) at the highest X-ray tube voltage (140 kV). ?/KAP values ranged between 1 and 5 mJ Gy(-1) cm(-2) in mammography and between 24 and 42 mJ Gy(-1) cm(-2) in CT. Changes in waveform ripple resulted in variations in ?/KAP of up to 15 %, similar to the effect of changes resulting in the choice of anode angle. For monoenergetic X-ray photons, there was a sigmoidal-type increase in ?/KAP from 2 mJ Gy(-1) cm(-2) at 20 keV to 42 mJ Gy(-1) cm(-2) at 80 keV. However, between 80 and 150 keV, the ?/KAP shows variations with changing photon energy of <10 %. Taking the average spectrum energy to consist of monoenergetic X rays generally overestimates the true value of ?/KAP. This study illustrated that the energy incident on a patient in any area of radiological imaging can be estimated from the total X-ray beam intensity (KAP) when X-ray beam quality is taken into account. Energy incident on the patient can be used to estimate the energy absorbed by the patient and the corresponding patient effective dose. PMID:24821931

  5. Is the dose equivalent index a practicable concept for use in regulations

    International Nuclear Information System (INIS)

    Additional limits are needed for supplementing, in regulations, the primary ICRP limits for effective dose equivalent and organ dose equivalents. In this paper quantities to be used for regulatory limiting of external irradiation are discussed. Possible quantities include exposure, air kerma, soft tissue absorbed dose, particle and energy fluence, and activity. These are compared with the absorbed dose index, and the dose equivalent index. It is concluded that the index quantities may be practicable for regulatory limitation of the direct external irradiation of individuals. In contrast, other quantities may be preferable for limitation of radiation fields where there is a potential risk for the irradiation of persons, and in particular those close to a radiation source, e.g. a consumer product. The dose equivalent index, as presently defined, does not seem recommendable for general use. (author)

  6. A conformal index determination to evaluate the prostate interstitial implants quality with high dose rate (HDR)

    International Nuclear Information System (INIS)

    For interstitial application of high dose rate (HDR) afterloading brachytherapy, generally a single stepping iridium-192 source is used, making possible optimization of the dose distribution by optimization of the relative time (dwell time) that the source remains at a certain position (dwell position). We analyzed the effects of geometric-volume optimization by three normalize methods in 22 prostate volume implants. In all patients the reference dose is specified at 85% of the mean central dose (as is done in the Paris System for dose specification. We compared the uniformity index, the irradiated volume, the total reference air kerma and a conformal index K that we introduce. It is clear from the table presented that the best optimization method is to normalize by a reference point and geometrical-volume optimization. The results show that the conformal index K presented is a useful and practical index to improve the quality of treatment of interstitial brachytherapy implants. (author)

  7. Effect of Scintillometer Height on Structure Parameter of the Refractive Index of Air Measurements

    Science.gov (United States)

    Gowda, P. H.; Howell, T. A.; Hartogensis, O.; Basu, S.; Scanlon, B. R.

    2009-12-01

    Scintillometers measure amount of scintillations by emitting a beam of light over a horizontal path and expresses as the atmospheric turbulence structure parameter as the refractive index of air (Cn2). Cn2 represents the turbulent strength of the atmosphere and describes the ability of the atmosphere to transport heat and humidity. The main objective of this study was to evaluate the effect of scintillometer height on Cn2 measurements and on the estimation of latent heat fluxes. The study was conducted during the 2009 summer growing season in the USDA-ARS Conservation and Production Research Laboratory (CPRL) at Bushland [350 11' N, 1020 06' W; 1,170 m elevation MSL], Texas. Field experiment consisted of two steps: (1) cross-calibration of scintillometers and (2) measurement of Cn2 at different heights. In the first step, three large aperture scintillometers (LAS) were deployed across two large lysimeter fields with bare soil surfaces. During the 3-week cross-calibration period, all three scintillometers were installed at a 2-m height with a path length of 420 m. Cn2 was monitored at a 1-min interval and averaged for 15-min periods. Cn2 measurements were synchronized with weather station and weighing lysimeter measurements. After the cross-calibration period, scintillometers were installed at 2-, 2.5- and 3-m heights, and Cn2 measurements were continued for another 3-week period. In addition to the Cn2 measurements, net radiation (Rn) and soil heat fluxes (G) were measured in both lysimeter fields. Cn2 values were corrected for inner scale dependence before cross calibration and estimation of sensible heat fluxes. Measurements of wind speed, air temperature, and relative humidity were used with Cn2 data to derive sensible heat fluxes. Latent heat fluxes were estimated as a residual from the energy balance and compared with lysimeter data. Results of cross calibration and effects of scintillometer height on the estimation of latent heat fluxes were reported and discussed.

  8. Exploring EKC, trends of growth patterns and air pollutants concentration level in Malaysia: A Nemerow Index Approach

    International Nuclear Information System (INIS)

    The present study examines an Environmental Kuznets Curve (EKC) hypothesis by analyzing annual data of air pollutants concentartion and per capita GDP as economic indicator over the (1996–2010) period in Malaysia. Nemerow Index Approach (I) used to generate a measures of air pollution. The results show that ambient air quality indicators supports the EKC hypothesis which stated that pollution levels increase as a country develops, but begin to decrease as rising incomes pass beyond a turning poin. Also, the I result is justifying that most pollutants are showing value less than 1.

  9. Solar radiation estimation using sunshine hour and air pollution index in China

    International Nuclear Information System (INIS)

    Highlights: • Aerosol can affect coefficients of A–P equation to estimate solar radiation. • Logarithmic model performed best, according to MBE, MABE, MPE, MAPE, RMSE and NSE. • Parameters of A–P model can be adjusted by API, geographical position and altitude. • A general equation to estimate solar radiation was established in China. - Abstract: Angström–Prescott (A–P) equation is the most widely used empirical relationship to estimate global solar radiation from sunshine hours. A new approach based on Air Pollution Index (API) data is introduced to adjust the coefficients of A–P equation in this study. Based on daily solar radiation, sunshine hours and API data at nine meteorological stations from 2001 to 2011 in China, linear, exponential and logarithmic models are developed and validated. When evaluated by performance indicators of mean bias error, mean absolute bias error, mean percentage error, mean absolute percentage error, root mean square error, and Nash–Sutcliffe Equation, it is demonstrated that logarithmic model performed better than the other models. Then empirical coefficients for three models are given for each station and the variations of these coefficients are affected by API, geographical position, and altitude. This indicates that aerosol can play an important role in estimation solar radiation from sunshine hours, especially in those highly polluted regions. Finally, a countrywide general equation is established based on the sunshine hour data, API and geographical parameters, which can be used to estimate the daily solar radiation in areas where the radiation data is not available

  10. Daily index of air pollution level; Indice giornaliero della qualita` dell`aria IGQA

    Energy Technology Data Exchange (ETDEWEB)

    Albergamo, C.; Cagnetti, P.; Mammarella, M. C.; Tondo, A. [ENEA, Centro Ricerche Casaccia, Rome (Italy). Dipt. Ambiente

    1997-05-01

    A daily evaluation of pollution level in urban area is the starting point to carry out any proper analysis of pollution data. In this paper an algorithm is stated in order to provide both a method to evaluate pollution level and a direct interpretation of resulting values according to the present law. Hour data, which is taken from surveying points, is previously transformed to daily data and then normalised to standard values. Afterwards, one value per pollutant is obtained as an index of the daily situation for the whole area. The operational choices in the algorithm are made with respect to the present law. The algorithm has been carried out by SAS language as a part of the project called A.T.M.O.S.F.E.R.A. (a decision-support-system developed by ENEA) to give a useful and intuitive instrument to spot critical situations for air pollution. The last part of the paper is an application to Rome data, from January 1992 to December 1996.

  11. Proceedings of the 20th DOE/NRC nuclear air cleaning conference: An index to the 1st--20th AEC/ERDA/DOE and DOE/NRC nuclear air cleaning conferences

    International Nuclear Information System (INIS)

    This document contains a cumulative index to the first through twentieth AEC, ERDA, DOE, and DOE/NRC Nuclear Air Cleaning Conferences and incorporates corrections of errors appearing in prior intermediate indexes

  12. Experimental hydrogen kerma factors for incident neutron energies from 25 to 75 MeV

    International Nuclear Information System (INIS)

    Hydrogen kerma factors and their uncertainties are deduced on an experimental basis, starting from our previously measured differential cross sections completed with available data from the literature, in the incident neutron energy range 25 to 75 MeV. The deduced experimental kerma factors are compared with theoretical predictions. A simple to use parametrization of the hydrogen kerma factor values in the incident neutron energy range 0.3 to 100 MeV is also proposed. (author)

  13. Development of a health-based air quality index for Canada : public opinion research 2004-05 : final report

    International Nuclear Information System (INIS)

    Canadians rely on an air quality indexes (AQIs) to inform them about air pollution conditions in their communities. However, there is no AQI common to all of Canada, and there is a lack of consistency in the way in which air quality is calculated and reported, as well as in the use of health-based messages. This paper reported findings of a public opinion research survey conducted to gauge Canadians' awareness, perceptions and behavioural responses to air quality, air pollution and AQIs. The aim of the study was to guide the development of health messages to more effectively communicate the AQI to Canadians with respect to the health risks associated with poor air quality. Telephone surveys were conducted immediately following a poor air quality episode to measure the public's awareness and response to these events, as well as residents' general awareness and use of AQIs. A separate research project was then conducted which consisted of in-depth qualitative interviews with 28 individuals recruited from the general population. A comprehensive national telephone survey was then conducted following the summer 2004 'smog season', which focused on the public's awareness of air pollution and AQIs. Results from the first 2 phases of the research were then presented at a workshop comprised of health and environmental communities specializing in air issues in Canada. Focus groups were then held to test public reaction to new AQI communications concepts derived from the research. Results indicated that Canadians widely identify air pollution as a significant environmental problem. However, the information from AQIs had a limited impact in terms of prompting actions to reduce personal exposure. A new type of national AQI for Canada was developed that conveyed information on air quality conditions and their significance. Key features include a 0 to 10 point unbounded scale showing current air quality conditions; a forecast of future conditions; standardized information covering health risks; targeted information for groups most at risk; and recommended activities

  14. Analysis of the Tandem Calibration Method for Kerma Area Product Meters Via Monte Carlo Simulations

    International Nuclear Information System (INIS)

    The IAEA recommends that uncertainties of dosimetric measurements in diagnostic radiology for risk assessment and quality assurance should be less than 7% on the confidence level of 95%. This accuracy is difficult to achieve with kerma area product (KAP) meters currently used in clinics. The reasons range from the high energy dependence of KAP meters to the wide variety of configurations in which KAP meters are used and calibrated. The tandem calibration method introduced by Poeyry, Komppa and Kosunen in 2005 has the potential to make the calibration procedure simpler and more accurate compared to the traditional beam-area method. In this method, two positions of the reference KAP meter are of interest: (a) a position close to the field KAP meter and (b) a position 20 cm above the couch. In the close position, the distance between the two KAP meters should be at least 30 cm to reduce the effect of back scatter. For the other position, which is recommended for the beam-area calibration method, the distance of 70 cm between the KAP meters was used in this study. The aim of this work was to complement existing experimental data comparing the two configurations with Monte Carlo (MC) simulations. In a geometry consisting of a simplified model of the VacuTec 70157 type KAP meter, the MCNP code was used to simulate the kerma area product, PKA, for the two (close and distant) reference planes. It was found that PKA values for the tube voltage of 40 kV were about 2.5% lower for the distant plane than for the close one. For higher tube voltages, the difference was smaller. The difference was mainly caused by attenuation of the X ray beam in air. Since the problem with high uncertainties in PKA measurements is also caused by the current design of X ray machines, possible solutions are discussed. (author)

  15. Development of a calibration methodology and tests of kerma area product meters

    International Nuclear Information System (INIS)

    The quantity kerma area product (PKA) is important to establish reference levels in diagnostic radiology exams. This quantity can be obtained using a PKA meter. The use of such meters is essential to evaluate the radiation dose in radiological procedures and is a good indicator to make sure that the dose limit to the patient's skin doesn't exceed. Sometimes, these meters come fixed to X radiation equipment, which makes its calibration difficult. In this work, it was developed a methodology for calibration of PKA meters. The instrument used for this purpose was the Patient Dose Calibrator (PDC). It was developed to be used as a reference to check the calibration of PKA and air kerma meters that are used for dosimetry in patients and to verify the consistency and behavior of systems of automatic exposure control. Because it is a new equipment, which, in Brazil, is not yet used as reference equipment for calibration, it was also performed the quality control of this equipment with characterization tests, the calibration and an evaluation of the energy dependence. After the tests, it was proved that the PDC can be used as a reference instrument and that the calibration must be performed in situ, so that the characteristics of each X-ray equipment, where the PKA meters are used, are considered. The calibration was then performed with portable PKA meters and in an interventional radiology equipment that has a PKA meter fixed. The results were good and it was proved the need for calibration of these meters and the importance of in situ calibration with a reference meter. (author)

  16. Kerma-factors in neutron interactions with lithium hydride

    International Nuclear Information System (INIS)

    Models to calculate heat generation in a substance have been developed for all kinds of neutron reactions in any energy range. The calculational model for kerma-factors is based on a precise solution of kinematic equations. The calculated kerma-factors for 6Li, 7Li, 1H (in terms of eVxb/atom) and for LiH with natural Li (in Wxs/cmxneutr) in the energy range from 10-4 to 107 eV are presented. In neutron interactions with 6Li the major contributions to heat generation were assumed to be from the 6Li(n,t)He reaction; with 7Li - from the reactions of elastic scattering, inelastic scattering on the level E=0.478 MeV, (n,n't) and (n,?); with hydrogen the main contribution is made from the reactions of elastic scattering and capture. Data of the ENDF/B-4 library and latest experimental results were used in the calculations. It is pointed out that the accuracy of the calculations depends only on the availability and accuracy of corresponding nuclear data

  17. [Analysis on Regional Characteristics of Air Quality Index and Weather Situation in Beijing and Its Surrounding Cities During the APEC].

    Science.gov (United States)

    Gao, Qing-xian; Lu, Jun-rong; Wang, Ning; Li, Wen-tao; Gao, Wen-kang; Su, Bu-da

    2015-11-01

    Analysis on the revolution and regional characteristics of air quality by hourly monitored readings from 1 to 15 November 2014 released by Environmental Monitoring Station of China and research of the impacts of weather situation and meteorological elements released by China Meteorological Administration towards air quality of Beijing and its surrounding cities during the Asia-Pacific Economic Cooperation (APEC) indicated that: (1) The air quality was good because of the implementation of mitigation measures, while the Air Quality Index (AQI) increased along with the termination of mitigation measures. Thus it can be seen that mitigation measures made a great contribution to the improvement of air quality of Beijing and its surrounding cities. (2) Affected by thermal inversion layer, AQI of Beijing and its surrounding cities increased quickly during the initial of the implemental of reducing measures which proved that pollutants would accumulate in the context of unfavourable weather, hence the influence of weather situation towards air quality could not be ignored. (3) Although affected by thermal inversion layer, the concentration of pollutants of Beijing was not accumulated to a high degree at the end period of reducing measures, while Tianjin, Tangshan, Baoding and Xingtai suffered from moderate and severe pollution at the same time which further illustrated that the implementation of mitigation measures have made a great contribution to the improvement of air quality in Beijing during APEC. PMID:26910978

  18. An evaluation model for air quality in underground uranium mines based on integrated scale index on weights of generalized contrast

    International Nuclear Information System (INIS)

    The shortcomings of traditional methods for evaluating air quality in underground uranium mines are analysis. Based on the analysis results and the principle that the concentration of the contaminants in a mine varies in a constant ratio and the degree of their hazard varies in an arithmetic progression, the evaluating indicators were determined for the air quality in a uranium mine, and an evaluation model was proposed for the evaluation of the air quality in a uranium mine based on integrated scale index on weights of generalized contrast. the model overcomes the shortcoming of traditional methods that the radiation hazard is considered mainly in all these methods. the model was used to evaluate the air quality of four places in an underground uranium mine, the grade of the air quality and the correspondingmeasures for controlling the air quality in the four places are determined. The evaluation results show that the model is applicable to the design of a ventilation system for an underground uranium mine and the evaluation of the air quality in the system. (authors)

  19. The use of evaluated nuclear data libraries for the calculation of kerma factors

    International Nuclear Information System (INIS)

    A computational model is developed for calculating neutron kerma factors and total energy of protons from basic nuclear data for all neutron reaction types in any energy range. The evaluated nuclear data libraries are used for calculating the kerma factors. (author). 4 refs

  20. Automatic unit for measuring refractive index of air based on Ciddor equation and its verification using direct interferometric measurement method.

    Czech Academy of Sciences Publication Activity Database

    Hucl, Václav; ?ížek, Martin; Hrabina, Jan; Mikel, B?etislav; ?e?ucha, Šimon; Buchta, Zden?k; Jedli?ka, Petr; Lešundák, Adam; Oulehla, Jind?ich; Mr?a, Libor; Šarbort, Martin; Šmíd, Radek; Lazar, Josef; ?íp, Ond?ej

    Bellingham : SPIE, 2013, 878837:1-9. ISBN 978-0-8194-9604-1. [Optical Measurement Systems for Industrial Inspection /8./. Munich (DE), 13.05.2013-16.05.2013] R&D Projects: GA ?R GAP102/10/1813; GA ?R GPP102/11/P819 Institutional support: RVO:68081731 Keywords : refractive index of air * precise measurement * laser interferometer Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  1. Position sensing with suppression of the drift of the refractive index of air for high resolution interferometry.

    Czech Academy of Sciences Publication Activity Database

    Holá, Miroslava; Buchta, Zden?k; ?íp, Ond?ej; Lazar, Josef

    Piscataway : IEEE, 2014. ISBN 978-1-4673-5225-3. [URSI General Assembly and Scientific Symposium (URSI GASS) 2014 /31./. Beijing (CN), 16.08.2014-23.08.2014] R&D Projects: GA TA ?R TA02010711; GA TA ?R TE01020233; GA MŠk(CZ) LO1212; GA MŠk ED0017/01/01 Institutional support: RVO:68081731 Keywords : refractive index of air * interferometry * Edlen formula Subject RIV: BH - Optics, Masers, Lasers

  2. A Visualization Approach to Air Pollution Data Exploration—A Case Study of Air Quality Index (PM2.5 in Beijing, China

    Directory of Open Access Journals (Sweden)

    Huan Li

    2016-02-01

    Full Text Available In recent years, frequent occurrences of significant air pollution events in China have routinely caused panic and are a major topic of discussion by the public and air pollution experts in government and academia. Therefore, this study proposed an efficient visualization method to represent directly, quickly, and clearly the spatio-temporal information contained in air pollution data. Data quality check and cleansing during a preliminary visual analysis is presented in tabular form, heat matrix, or line chart, upon which hypotheses can be deduced. Further visualizations were designed to verify the hypotheses and obtain useful findings. This method was tested and validated in a year-long case study of the air quality index (AQI of PM2.5 in Beijing, China. We found that PM2.5, PM10, and NO2 may be emitted by the same sources, and strong winds may accelerate the spread of pollutants. The average concentration of PM2.5 in Beijing was greater than the AQI value of 50 over the six-year study period. Furthermore, arable lands exhibited considerably higher concentrations of air pollutants than vegetation-covered areas. The findings of this study showed that our visualization method is intuitive and reliable through data quality checking and information sharing with multi-perspective air pollution graphs. This method allows the data to be easily understood by the public and inspire or aid further studies in other fields.

  3. 40 CFR Appendix G to Part 58 - Uniform Air Quality Index (AQI) and Daily Reporting

    Science.gov (United States)

    2010-07-01

    ...of public access, or by any other means, including a recorded phone message, a public Internet site, or facsimile transmission...index value as the AQI for O3 . ER27MR08.001 Where: Ip = the index value for pollutantp Cp = the truncated...

  4. How the consumer confidence index could increase air travel demand forecast accuracy?

    OpenAIRE

    Teyssier, Narjesse

    2012-01-01

    Because of the complex nature of the air transportation industry with continuous changes in the environment, the past records of air traffic forecasters, either using trend extrapolation or causal models or even more sophisticated methods have not produced accurate results. In recent years, the trend has been to develop air travel demand forecasts based on econometric equations, which specify a relationship between passenger traffic and a number of traditional key economic variables. However ...

  5. A Satellite-Based Multi-Pollutant Index of Global Air Quality

    Science.gov (United States)

    Cooper, Mathew J.; Martin, Randall V.; vanDonkelaar, Aaron; Lamsal, Lok; Brauer, Michael; Brook, Jeffrey R.

    2012-01-01

    Air pollution is a major health hazard that is responsible formillions of annual excess deaths worldwide. Simpleindicators are useful for comparative studies and to asses strends over time. The development of global indicators hasbeen impeded by the lack of ground-based observations in vast regions of the world. Recognition is growing of the need for amultipollutant approach to air quality to better represent human exposure. Here we introduce the prospect of amultipollutant air quality indicator based on observations from satellite remote sensing.

  6. DISDOS, Kerma in Model Man from External Gamma Source

    International Nuclear Information System (INIS)

    1 - Description of problem or function: The absorbed dose (actually Kerma) is calculated for simplified human phantoms (elliptical cylinders) irradiated by external photon sources. The phantoms are divided into three parts: head, trunk, and legs. Three source distributions are considered: collimated beam, point source, and isotropic irradiation; other sources may be considered since the codes are segmented. 2 - Method of solution: Monte Carlo calculations provide estimates of the dose and the standard deviation in each zone. The source energy spectrum may be discrete, uniformly distributed in an energy range, or given by a piece-wise continuous function. 3 - Restrictions on the complexity of the problem: Pair production is accounted for in the field of the nuclei only. Electron binding corrections to Compton scattering are omitted. The body has 22 organs

  7. Secondary bremsstrahlung and the energy-conservation aspects of kerma in photon-irradiated media

    Science.gov (United States)

    Kumar, Sudhir; Nahum, Alan E.

    2016-02-01

    Kerma, collision kerma and absorbed dose in media irradiated by megavoltage photons are analysed with respect to energy conservation. The user-code DOSRZnrc was employed to compute absorbed dose D, kerma K and a special form of kerma, K ncpt, obtained by setting the charged-particle transport energy cut-off very high, thereby preventing the generation of ‘secondary bremsstrahlung’ along the charged-particle paths. The user-code FLURZnrc was employed to compute photon fluence, differential in energy, from which collision kerma, K col and K were derived. The ratios K/D, K ncpt/D and K col/D have thereby been determined over a very large volumes of water, aluminium and copper irradiated by broad, parallel beams of 0.1 to 25 MeV monoenergetic photons, and 6, 10 and 15 MV ‘clinical’ radiotherapy qualities. Concerning depth-dependence, the ‘area under the kerma, K, curve’ exceeded that under the dose curve, demonstrating that kerma does not conserve energy when computed over a large volume. This is due to the ‘double counting’ of the energy of the secondary bremsstrahlung photons, this energy being (implicitly) included in the kerma ‘liberated’ in the irradiated medium, at the same time as this secondary bremsstrahlung is included in the photon fluence which gives rise to kerma elsewhere in the medium. For 25 MeV photons this ‘violation’ amounts to 8.6%, 14.2% and 25.5% in large volumes of water, aluminium and copper respectively but only 0.6% for a ‘clinical’ 6 MV beam in water. By contrast, K col/D and K ncpt/D, also computed over very large phantoms of the same three media, for the same beam qualities, are equal to unity within (very low) statistical uncertainties, demonstrating that collision kerma and the special type of kerma, K ncpt, do conserve energy over a large volume. A comparison of photon fluence spectra for the 25 MeV beam at a depth of???51?g cm?2 for both very high and very low charged-particle transport cut-offs reveals the considerable contribution to the total photon fluence by secondary bremsstrahlung in the latter case. Finally, a correction to the ‘kerma integral’ has been formulated to account for the energy transferred to charged particles by photons with initial energies below the Monte-Carlo photon transport cut-off PCUT; for 25 MeV photons this ‘photon track end’ correction is negligible for all PCUT below 10 keV.

  8. 40 CFR Appendix G to Part 58 - Uniform Air Quality Index (AQI) and Daily Reporting

    Science.gov (United States)

    2010-07-01

    ... (SLAMS) or parts of the SLAMS required by 40 CFR 58.10 for each pollutant except PM. For PM, calculate... the nearest integer. Table 2—Breakpoints for the AQI These breakpoints O3 (ppm)8-hour O3 (ppm)1-hour1... Index (AQI). U.S. Environmental Protection Agency, research Triangle Park, NC....

  9. The role of air pollution in the relationship between a heat stress index and human mortality in Toronto

    International Nuclear Information System (INIS)

    In this study we considered confounding from air pollutants and chronological variables in the relation between humidex, a summer temperature and humidity index, and nonaccidental mortality, from 1980-1996 in Toronto, Canada. Changes in the risk of death by age group, gender, and combined cardiac-respiratory cause of death were estimated for both 1 deg. C and 50-95th percentile increases in humidex using a generalized additive linear model. With air pollution terms in the models, relative risk (RR) point estimates narrowly exceeded 1.0 for all groups. Humidex effects were most apparent for females (RR=1.006, 95% CI=1.004-1.008 per 1 deg. C humidex and RR=1.089, 95% CI=1.058-1.121 for 50th to 95th percentile humidex). When air pollution was omitted from the model, RR in the 50-95th percentile analysis increased less than 1.71% for all groups except females, for which RR decreased 1.42%. Differences in RR per 1 deg. C humidex were all less than 0.12%. Confidence intervals narrowed slightly for all groups investigated. Heat stress has a statistically significant, yet minimal impact on Toronto populations, and air pollution does appear to have a small, but consistent confounding effect on humidex effect estimates

  10. PLAM - a meteorological pollution index for air quality and its applications in fog-haze forecasts in north China

    Science.gov (United States)

    Yang, Y.; Wang, J.; Gong, S.; Zhang, X.; Wang, H.; Wang, Y.; Wang, J.; Li, D.; Guo, J.

    2015-03-01

    Using surface meteorological observation and high resolution emission data, this paper discusses the application of PLAM/h Index (Parameter Linking Air-quality to Meteorological conditions/haze) in the prediction of large-scale low visibility and fog-haze events. Based on the two-dimensional probability density function diagnosis model for emissions, the study extends the diagnosis and prediction of the meteorological pollution index PLAM to the regional visibility fog-haze intensity. The results show that combining the influence of regular meteorological conditions and emission factors together in the PLAM/h parameterization scheme is very effective in improving the diagnostic identification ability of the fog-haze weather in North China. The correlation coefficients for four seasons (spring, summer, autumn and winter) between PLAM/h and visibility observation are 0.76, 0.80, 0.96 and 0.86 respectively and all their significance levels exceed 0.001, showing the ability of PLAM/h to predict the seasonal changes and differences of fog-haze weather in the North China region. The high-value correlation zones are respectively located in Jing-Jin-Ji (Beijing, Tianjin, Hebei), Bohai Bay rim and the southern Hebei-northern Henan, indicating that the PLAM/h index has relations with the distribution of frequent heavy fog-haze weather in North China and the distribution of emission high-value zone. Comparatively analyzing the heavy fog-haze events and large-scale fine weather processes in winter and summer, it is found that PLAM/h index 24 h forecast is highly correlated to the visibility observation. Therefore, PLAM/h index has better capability of doing identification, analysis and forecasting.

  11. Measurement of the nonlinear refractive index of air constituents at mid-infrared wavelengths

    CERN Document Server

    Zahedpour, S; Milchberg, H M

    2015-01-01

    We measure the nonlinear refractive index coefficients in N$_2$, O$_2$ and Ar from visible through mid-infrared wavelengths (\\lambda = 0.4 - 2.4 {\\mu}m). The wavelengths investigated correspond to transparency windows in the atmosphere. Good agreement is found with theoretical models of $\\chi^{(3)}$. Our results are essential for accurately simulating the propagation of ultrashort mid-IR pulses in the atmosphere.

  12. High-accuracy self-correction of refractive index of air using two-color interferometry of optical frequency combs.

    Science.gov (United States)

    Minoshima, Kaoru; Arai, Kaoru; Inaba, Hajime

    2011-12-19

    Long-path pulse-to-pulse interferometers of two-color frequency combs are developed using fundamental and second harmonics of a mode-locked fiber laser. Interferometric phase difference between two-color frequency combs was precisely measured by stabilizing the fundamental fringe phase by controlling the repetition frequency of the comb, and a stability of 10(-10) for 1000 s was achieved in the measurement of an optical path length difference between two wavelengths. In long-term measurements performed for 10 h, results of phase variation of interferometric measurements were highly consistent with the fluctuations in the calculated difference of refractive indices of air at two wavelengths with an accuracy of 10(-10). The difference between the measured optical distances corresponding to two wavelengths and the optical distance corresponding to the fundamental wavelength were used in the two-color method; high-accuracy self-correction of the fluctuation of refractive index of air was performed with an uncertainty of 5 × 10(-8) for 10-h measurements when the maximum refractive index change was on the order of 10(-6). PMID:22274198

  13. Cumulative Impact Evaluation in Central Part of Liepaja with Comulative Pollution Index Method and Air Pollution Dispersion Modelling

    Directory of Open Access Journals (Sweden)

    Kalni?š Viesturs

    2015-07-01

    Full Text Available Cumulative impact evaluation is one of the most actual problems in air quality monitoring. At the same time, it is also the most problematic factor to evaluate due to lack of appropriate methodology. The aim of this study was to assess the opportunity to use a new method – Cumulative Pollution Index (CPI in cumulative impact calculation from two different sets of data – bioindication survey with Index of Atmospheric Purity method and air pollution dispersion modelling. Results show that the usage of modelling data, instead of measurements, in cumulative impact evaluation can be quite difficult due to the fact that dispersion models not always give sufficiently accurate data. Despite the issues with modelling specifics, the use of dispersion modelling in CPI calculation shows that the use of this approach not only gives plausible data – obtained values correlate with pollution level and forming strong clustering in spatial distribution, but also reveals new facts about cumulative impact – demonstrates the city microclimate importance in forming of cumulative effect due to geometry of street canyons.

  14. Association between indoor air pollutant exposure and blood pressure and heart rate in subjects according to body mass index.

    Science.gov (United States)

    Jung, Chien-Cheng; Su, Huey-Jen; Liang, Hsiu-Hao

    2016-01-01

    This study investigates the effects of high body mass index (BMI) of subjects on individual who exhibited high cardiovascular disease indexes with blood pressure (BP) and heart rate (HR) when exposed to high levels of indoor air pollutants. We collected 115 office workers, and measured their systolic blood pressure (SBP), diastolic blood pressure (DBP) and HR at the end of the workday. The subjects were divided into three groups according to BMI: 18-24 (normal weight), 24-27 (overweight) and >27 (obese). This study also measured the levels of carbon dioxide (CO2), total volatile organic compounds (TVOC), particulate matter with an aerodynamic diameter less than 2.5μm (PM2.5), as well as the bacteria and fungi in the subjects' work-places. The pollutant effects were divided by median. Two-way analysis of variance (ANOVA) was used to analyze the health effects of indoor air pollution exposure according to BMI. Our study showed that higher levels of SBP, DBP and HR occurred in subjects who were overweight or obese as compared to those with normal weight. Moreover, there was higher level of SBP in subjects who were overweight or obese when they were exposed to higher levels of TVOC and fungi (p<0.05). We also found higher value for DBP and HR with increasing BMI to be associated with exposure to higher TVOC levels. This study suggests that individuals with higher BMI have higher cardiovascular disease risk when they are exposed to poor indoor air quality (IAQ), and specifically in terms of TVOC. PMID:26363400

  15. Air Pollution Tolerance Index (APTI) of some tree species growing near rail roads of Madurai, Tamil Nadu (India).

    Science.gov (United States)

    Thambavani, D Sarala; Kamala, C

    2010-10-01

    Biological monitoring and assessment studies due to urban--rail road pollutants were carried out using Air Pollution Tolerance Index (APTI) of plants. Four plant (leaf) parameters--namely ascorbic acid, total chlorophyll, relative water content and leaf extract pH were combined together in a formulation signifying the APTI of plants. APTI was calculated for five different species such as Azadirachta indica, Delonix regia, Ficus religiosa, Pongamia pinnata and Polyalthia longifolia growing in two different areas, i.e. control area and along the railway track of Madurai, Tamil Nadu (India). The control site was selected in the college campus. None of the four plant parameters indicated a consistent response to pollutants. In the present study, Delonix regia and Pongamia pinnata lost the tolerance towards air pollutants and became more sensitive, but Azadirachta indica, Ficus religiosa, and Polyalthia longifolia indicated high APTI values over control area and hence considered as tolerant species. The APTI of plants showed a marked gradation as the pollutant load decreased from rail road to control area. The APTI can be used as a good indicator of impact of the air pollution on plants. PMID:22312796

  16. Humidity dependence in kerma area product meter used in diagnostic X ray examinations

    International Nuclear Information System (INIS)

    The air-kerma area product, PKA, is a dosimetric quantity that can be directly related to the patient dose and used for risk assessment associated with different x-ray examinations. PKA has the unit Gym2 and can be directly measured by use of a Kerma Area Product (KAP) meter placed in the radiation beam. PKA is the recommended quantity for use in the establishment of diagnostic reference levels (DRLs) for conventional x-ray examinations and is also a good indicator for when threshold doses for deterministic effects are reached in interventional x-ray procedures. Most modern x-ray equipment provides the operator with the total PKA from the examination or procedure. This PKA is either obtained from PKA measurements from a built-in KAP meter or calculated from exposure parameters. To get a reliable estimate of DRLs and the patient dose, it is essential that the PKA measurement is correct. Thus all environmental influences on the KAP meter should be taken into account. These influences can either be corrected for or included in the measurement uncertainty. These have to be considered both in the calibration of the KAP-meters, in the use of the KAP meters and in the determination of DRLs. A KAP meter is an electrometer and a plane parallel ion chamber with an active area of typical 15 cm X 15 cm. The KAP meter usually consist of three plastic plates (PMMA) which is coated with a conducting layer made of indium oxide doped with tin (In2O3:Sn). This coating is used due to its transparency to light. The air layers between the plates (sensitive volume) are open to the air. Thus the readings from the KAP meter have to be corrected for air pressure and temperature as for other ion chambers. It has been assumed that the humidity dependence of the KAP meter is so small that no correction has been necessary. This work will show that KAP meter with PMMA plastic plates coated with In2O3:Sn shows a humidity dependence so large that corrections should be considered. The measurements were performed by carefully controlling the humidity in the laboratory. Between each measurement the humidity was changed with steps of 5 to 10 %RH in the range 20-60 %RH. The measurements were performed two days after the humidity change, so the humidity inside the chamber could stabilise. The setup was as for a substitution calibration with the KAP meter 100 cm from the x- ray source and exposed to a beam limited by a aperture of 5 cm X 5 cm at 95 cm as described in TRS-457. A Capintec PR-30 was used as a monitor chamber. This chamber is made of C-552 and has small humidity dependence. Two KAP-chambers were tested. Both chambers showed the same humidity dependence. The humidity dependence for the chambers was (0.24 ± 0.10) % pr. %RH (k=2). The transmission factor of the chambers showed no humidity dependence. One of the chambers were tested at five different qualities from 40 kV to 150 kV (RQR2, RQR5, RQR8, RQR9, RQR 10). The humidity dependence was the same for all qualities. In an environment with no humidity control the humidity can typically vary from 20 %RH to 80 %RH. According to the results this can lead to about 14 % change in the KAP reading. This is a larger effect than recommended for KAP meters, ± 3.0 %, in the IEC 60580 standard. The observed humidity dependence means that great care have to be take when calibrating and using KAP meter for dose measurements. The humidity effect is not fully understood but it seems that the conducting layer on the PMMA is the origin of the effect

  17. Kerma factor evaluation and its application in nuclear heating experiment analysis

    International Nuclear Information System (INIS)

    The accuracy of calculating 'kerma factor', which is the response function for nuclear heating is very important in many applications, particularly fusion systems. A computer code, called MAZE, has been developed primarily for evaluating neutron and gamma kerma factors based on an improved modeling and a capability to analyze basic data and evaluate consistency in preserving energy. Kinematics equations and energy conservation considerations are modeled in the code. The code has features that allow comparison and analysis among different methods of calculating the kerma factor and it provides users with data information needed to make user-oriented selections from two to three, often different, results. A kerma factor library, called MAZE-LIB, has been generated with MAZE for most of the materials of interest in fusion based on the most recent and accurate data available, FENDL library, which is the nuclear data library selected by ITER. The kerma factor library provided in this work is the result of an extensive analysis of nuclear data and careful selection from among often different results from the different calculational methods. It was shown that some data inconsistency problems in preserving the energy still exist in the FENDL library. Some problems with the widely used computer code NJOY were exposed during the process of the kerma factor evaluation, which is crucial at this stage of fusion research, since NJOY is the primary nuclear data processing code selected by ITER. Comparison with nuclear heating experimental data, derived from very recent integral experiments with 14 MeV neutrons and the analysis of the uncertainty in prediction have been carried out using the newly developed kerma factors. (orig.)

  18. Improving Neural Network Prediction Accuracy for PM10 Individual Air Quality Index Pollution Levels.

    Science.gov (United States)

    Feng, Qi; Wu, Shengjun; Du, Yun; Xue, Huaiping; Xiao, Fei; Ban, Xuan; Li, Xiaodong

    2013-12-01

    Fugitive dust deriving from construction sites is a serious local source of particulate matter (PM) that leads to air pollution in cities undergoing rapid urbanization in China. In spite of this fact, no study has yet been published relating to prediction of high levels of PM with diameters neural network models (multilayer perceptron, Elman, and support vector machine) in predicting daily PM10 IAQI one day in advance. To obtain acceptable forecasting accuracy, measured time series data were decomposed into wavelet representations and wavelet coefficients were predicted. Effectiveness of these forecasters were tested using a time series recorded between January 1, 2005, and December 31, 2011, at six monitoring stations situated within the urban area of the city of Wuhan, China. Experimental trials showed that the improved models provided low root mean square error values and mean absolute error values in comparison to the original models. In addition, these improved models resulted in higher values of coefficients of determination and AHPC (the accuracy rate of high PM10 IAQI caused by nearby construction activity) compared to the original models when predicting high PM10 IAQI levels attributable to fugitive dust from nearby construction sites. PMID:24381481

  19. Determination of mass attenuation coefficients, effective atomic and electron numbers, mean free paths and kermas for PbO, barite and some boron ores

    International Nuclear Information System (INIS)

    The total mass attenuation coefficients, ?m, for PbO, barite, colemanite, tincal and ulexite were determined at 80.1, 302.9, 356.0, 661.7 and 1250.0 keV photon energies by using NaI (Tl) scintillation detector. Effective atomic number, Zeff, effective electron number, Neff, total atomic cross-section, ?t, total electronic cross-section, ?e, mean free path, mfp, and kerma relative to air were determined experimentally and theoretically. The theoretical mass attenuation coefficients were estimated using mixture rule. The calculated values were compared with the experimental values for all samples.

  20. Determination of mass attenuation coefficients, effective atomic and electron numbers, mean free paths and kermas for PbO, barite and some boron ores

    Science.gov (United States)

    Un, A.; Sahin, Y.

    2011-07-01

    The total mass attenuation coefficients, ? m, for PbO, barite, colemanite, tincal and ulexite were determined at 80.1, 302.9, 356.0, 661.7 and 1250.0 keV photon energies by using NaI (Tl) scintillation detector. Effective atomic number, Z eff, effective electron number, N eff, total atomic cross-section, ? t, total electronic cross-section, ? e, mean free path, mfp, and kerma relative to air were determined experimentally and theoretically. The theoretical mass attenuation coefficients were estimated using mixture rule. The calculated values were compared with the experimental values for all samples.

  1. High NDVI and Potential Canopy Photosynthesis of South American Subtropical Forests despite Seasonal Changes in Leaf Area Index and Air Temperature

    OpenAIRE

    Piedad M. Cristiano; Nora Madanes; Paula I. Campanello; Débora di Francescantonio; Sabrina A. Rodríguez; Yong-Jiang Zhang; Laureano Oliva Carrasco; Guillermo Goldstein

    2014-01-01

    The canopy photosynthesis and carbon balance of the subtropical forests are not well studied compared to temperate and tropical forest ecosystems. The main objective of this study was to assess the seasonal dynamics of Normalized Difference Vegetation Index (NDVI) and potential canopy photosynthesis in relation to seasonal changes in leaf area index (LAI), chlorophyll concentration, and air temperatures of NE Argentina subtropical forests throughout the year. We included in the analysis sever...

  2. Air

    Science.gov (United States)

    ... to protect yourself from dirty air . Indoor air pollution and outdoor air pollution Air can be polluted indoors and it can ... comes from the natural breakdown of uranium in soil, rock, and water and gets into the air ...

  3. Air ion and pollution index variation for indoor and outdoor atmosphere at rural station Ramanandnagar (17° 4?N, 74° 25?) India

    Indian Academy of Sciences (India)

    S D Pawar

    2013-02-01

    In the present study, the observation of indoor air ion concentration at a rural site has been carried out for the first time. These indoor observations are compared with outdoor air ion concentration. Net charge can be introduced into the atmosphere by processes such as combustion, rainfall and ultraviolet radiation. As compared to indoors, average air ions of both the polarities at outdoors are higher. Moreover, the air ion concentrations, experience large fluctuations during daytime, as compared to nighttime values. Positive and negative air ion concentrations are lower and uniform throughout the night both for indoor and outdoor conditions. Pollution index is more or less unity for outdoors in all-the-time period, which is good for human health. Due to limited sources of air ions indoors, it is observed that pollution index decreases from 00:00–02:00 hours and minimum is reached during 12:00–14:00 hours for indoors. During 00:00–02:00 hours, the indoor pollution index is 1.55, which is very harmful to human health.

  4. Wind erosion risk in the southwest of Buenos Aires Province, Argentina, and its relationship to the productivity index

    Science.gov (United States)

    Silenzi, Juan C.; Echeverría, Nora E.; Vallejos, Adrián G.; Bouza, Mariana E.; De Lucia, Martín P.

    2012-01-01

    Wind erosion risk (WER) for soils of each municipality in the southwest (SW) of Buenos Aires Province (10,491,172 ha) was determined using the wind erosion equation (WEQ) model. WER results from multiplying the soil erodibility index (" I") of the soil by the climatic factor ( C). WER (Mg ha -1 year -1) of each municipality was: Bahía Blanca: 22.4, Coronel Dorrego: 18.6, Coronel Pringles: 4.5, Coronel Rosales: 48.2, Coronel Suárez: 4.5, Guaminí: 3.0, Patagones: 104.6, Puan: 12.2, Saavedra: 3.0, Tornquist: 6.8, and Villarino: 31.7. The maximum weighted average of " I" (Mg ha -1 year -1) corresponded to Coronel Rosales (87.6), Patagones (87.2), Villarino (85.7), Puan (67.9); Guaminí (59.6), Coronel Dorrego (53.1), and Bahía Blanca (39.3); the remaining municipalities ranged between 34.9 and 32.1 Mg ha -1 year -1. The highest C (%) corresponded to Patagones (120), Bahía Blanca (57), Coronel Rosales (55), Villarino (37), Coronel Dorrego (35), Tornquist (21), and Puan (18); for the remaining municipalities it was 14%. The productivity index (PI) is known to establish a numerical value of the productive capacity of lands. The relationship between WER and PI, weighted averages, in all the studied municipalities was fitted by means of a linear model, WER (Mg ha -1 year -1) = 95.23 - 2.09 * PI (%) ( R2 = 66%), and a second-order polynomial model, WER (Mg ha -1 year -1) = 139.41 - 5.86 * PI (%) + 0.07 * PI 2 (%) ( R2 = 74%). No statistically significant relationship was found between WER and PI for each municipality.

  5. Calculated photon KERMA factors based on the LLNL EGDL [Evaluated Gamma-Ray Data Library] data file

    International Nuclear Information System (INIS)

    Photon (Gamma-Ray) KERMA factors calculated from the LLNL EGDL (Evaluated Gamma-Ray Data Library) file are tabulated for the elements from Z=1 to Z=30 and for 15 composite materials. The KERMA factors are presented for 191 energy groups over the incident photon energy range from 100 eV to 100 MeV. 3 refs

  6. Spatial and temporal analysis of Air Pollution Index and its timescale-dependent relationship with meteorological factors in Guangzhou, China, 2001–2011

    International Nuclear Information System (INIS)

    There is an increasing interest in spatial and temporal variation of air pollution and its association with weather conditions. We presented the spatial and temporal variation of Air Pollution Index (API) and examined the associations between API and meteorological factors during 2001–2011 in Guangzhou, China. A Seasonal-Trend Decomposition Procedure Based on Loess (STL) was used to decompose API. Wavelet analyses were performed to examine the relationships between API and several meteorological factors. Air quality has improved since 2005. APIs were highly correlated among five monitoring stations, and there were substantial temporal variations. Timescale-dependent relationships were found between API and a variety of meteorological factors. Temperature, relative humidity, precipitation and wind speed were negatively correlated with API, while diurnal temperature range and atmospheric pressure were positively correlated with API in the annual cycle. Our findings should be taken into account when determining air quality forecasts and pollution control measures. - Highlights: • Air pollution is still serious in Guangzhou, China. • Air Pollution Index was associated with a variety of meteorological parameters. • The temporal relationships were timescale-dependent. • The findings should be taken into account in air quality forecasts and pollution control. - Spatial and temporal variation of API and its timescale-dependent relationship with meteorological factors in Guangzhou were demonstrated

  7. Measurement of air-refractive-index fluctuation from laser frequency shift with uncertainty of order 10?9

    International Nuclear Information System (INIS)

    In the previous work (Ishige et al 2009 Meas. Sci. Technol. 20 084019), we presented a method of measuring the relative air-refractive-index fluctuation (?nair) from the laser frequency shift with the measurement uncertainty of order 10?8 using a phase modulation homodyne interferometer (Basile et al 1991 Metrologia 28 455), which was supported by an ultralow thermal expansion material (ULTEM) and an external cavity laser diode (ECLD). In this paper, an improvement in the uncertainty of the ?nair measurement is presented. The improvement method is based on a Fabry–Perot cavity constructed on the ULTEM, which has a thermal expansion coefficient of 2 × 10?8 K?1 and an ECLD. The Pound–Drever–Hall method (Drever et al 1983 Appl. Phys. B 31 97) is also used to control the ECLD frequency to track the resonance of the cavity. ?nair can be derived from the ECLD frequency shift. The estimated measurement uncertainty of ?nair for a short time (?150 s) in the experiment is of order 2.5 × 10?9 or less

  8. Precision measurement of refractive index of air based on laser synthetic wavelength interferometry with Edlén equation estimation

    Science.gov (United States)

    Yan, Liping; Chen, Benyong; Zhang, Enzheng; Zhang, Shihua; Yang, Ye

    2015-08-01

    A novel method for the precision measurement of refractive index of air (nair) based on the combining of the laser synthetic wavelength interferometry with the Edlén equation estimation is proposed. First, a nair_e is calculated from the modified Edlén equation according to environmental parameters measured by low precision sensors with an uncertainty of 10-6. Second, a unique integral fringe number N corresponding to nair is determined based on the calculated nair_e. Then, a fractional fringe ? corresponding to nair with high accuracy can be obtained according to the principle of fringe subdivision of laser synthetic wavelength interferometry. Finally, high accurate measurement of nair is achieved according to the determined fringes N and ?. The merit of the proposed method is that it not only solves the problem of the measurement accuracy of nair being limited by the accuracies of environmental sensors, but also avoids adopting complicated vacuum pumping to measure the integral fringe N in the method of conventional laser interferometry. To verify the feasibility of the proposed method, comparison experiments with Edlén equations in short time and in long time were performed. Experimental results show that the measurement accuracy of nair is better than 2.5 × 10-8 in short time tests and 6.2 × 10-8 in long time tests.

  9. Use of Segregation Indices, Townsend Index, and Air Toxics Data to Assess Lifetime Cancer Risk Disparities in Metropolitan Charleston, South Carolina, USA

    Directory of Open Access Journals (Sweden)

    LaShanta J. Rice

    2014-05-01

    Full Text Available Background: Studies have demonstrated a relationship between segregation and level of education, occupational opportunities, and risk behaviors, yet a paucity of research has elucidated the association between racial residential segregation, socioeconomic deprivation, and lifetime cancer risk. Objectives: We examined estimated lifetime cancer risk from air toxics by racial composition, segregation, and deprivation in census tracts in Metropolitan Charleston. Methods: Segregation indices were used to measure the distribution of groups of people from different races within neighborhoods. The Townsend Index was used to measure economic deprivation in the study area. Poisson multivariate regressions were applied to assess the association of lifetime cancer risk with segregation indices and Townsend Index along with several sociodemographic measures. Results: Lifetime cancer risk from all pollution sources was 28 persons/million for half of the census tracts in Metropolitan Charleston. Isolation Index and Townsend Index both showed significant correlation with lifetime cancer risk from different sources. This significance still holds after adjusting for other sociodemographic measures in a Poisson regression, and these two indices have stronger effect on lifetime cancer risk compared to the effects of sociodemographic measures. Conclusions: We found that material deprivation, measured by the Townsend Index and segregation measured by the Isolation index, introduced high impact on lifetime cancer risk by air toxics at the census tract level.

  10. Energy absorption buildup factors, exposure buildup factors and Kerma for optically stimulated luminescence materials and their tissue equivalence for radiation dosimetry

    International Nuclear Information System (INIS)

    Optically stimulated luminescence (OSL) materials are sensitive dosimetric materials used for precise and accurate dose measurement for low-energy ionizing radiation. Low dose measurement capability with improved sensitivity makes these dosimeters very useful for diagnostic imaging, personnel monitoring and environmental radiation dosimetry. Gamma ray energy absorption buildup factors and exposure build factors were computed for OSL materials using the five-parameter Geometric Progression (G-P) fitting method in the energy range 0.015–15 MeV for penetration depths up to 40 mean free path. The computed energy absorption buildup factor and exposure buildup factor values were studied as a function of penetration depth and incident photon energy. Effective atomic numbers and Kerma relative to air of the selected OSL materials and tissue equivalence were computed and compared with that of water, PMMA and ICRU standard tissues. The buildup factors and kerma relative to air were found dependent upon effective atomic numbers. Buildup factors determined in the present work should be useful in radiation dosimetry, medical diagnostics and therapy, space dosimetry, accident dosimetry and personnel monitoring. - Highlights: • EABF and EBF values of OSL materials have been calculated using G-P fitting method. • Zeff of OSL materials was observed higher than water, PMMA and standard ICRU tissues. • EABF, EBF and Ka were found Zeff dependent. • Ka of BeO roughly independent upon photon energies. • We found BeO the most promising OSL material for clinical and medical dosimetry

  11. Energy absorption buildup factors, exposure buildup factors and Kerma for optically stimulated luminescence materials and their tissue equivalence for radiation dosimetry

    Science.gov (United States)

    Singh, Vishwanath P.; Badiger, N. M.

    2014-11-01

    Optically stimulated luminescence (OSL) materials are sensitive dosimetric materials used for precise and accurate dose measurement for low-energy ionizing radiation. Low dose measurement capability with improved sensitivity makes these dosimeters very useful for diagnostic imaging, personnel monitoring and environmental radiation dosimetry. Gamma ray energy absorption buildup factors and exposure build factors were computed for OSL materials using the five-parameter Geometric Progression (G-P) fitting method in the energy range 0.015-15 MeV for penetration depths up to 40 mean free path. The computed energy absorption buildup factor and exposure buildup factor values were studied as a function of penetration depth and incident photon energy. Effective atomic numbers and Kerma relative to air of the selected OSL materials and tissue equivalence were computed and compared with that of water, PMMA and ICRU standard tissues. The buildup factors and kerma relative to air were found dependent upon effective atomic numbers. Buildup factors determined in the present work should be useful in radiation dosimetry, medical diagnostics and therapy, space dosimetry, accident dosimetry and personnel monitoring.

  12. Evaluation of neutron-6Li and -7Li interaction cross-sections for calculating kerma factors

    International Nuclear Information System (INIS)

    On the basis of an analysis of experimental data the neutron-6Li and -7Li interaction cross sections are evaluated and the kerma factors are calculated in the most important energy region for neutron slowing-down: 0.001-16 MeV. A detailed study is made of the deuterium and tritium build-up reactions

  13. Review of the research and application of KERMA factor and DPA cross section

    International Nuclear Information System (INIS)

    The data for recoil atom spectra, KERMA factor and displacement cross sections from neutron-induced reactions are calling increasing interest for applications to the study of radiation damage, calculation of heat generation in reactor, neutron therapy and biological research. PKA spectra sub-working group was recently established in Japanese Nuclear Data Committee as a part of developing JENDL Special Purpose Data Files. Current status of the data and various features of application of the KERMA-related problems were reviewed and discussed at the first meeting of the sub-working group. Present report is a compilation of the items presented at the meeting, covering a brief review of the existing research and the data, method of calculation, the KERMA factor data in neutron therapy, the deduction of KERMA factor of C-12 from neutron reaction measurement and analysis, the data base for radiation damage, the damage simulation calculation, and the method of storaging the evaluated data in ENDF/B-VI format. (author)

  14. Measurement of the tissue to A-150 tissue equivalent plastic kerma ratio at two p(66)Be neutron therapy facilities

    International Nuclear Information System (INIS)

    The ICRU tissue to A-150 tissue equivalent plastic kerma ratio is needed for neutron therapy dosimetry. The current ICRU protocol for neutron dosimetry recommends using a common conversion factor of 0.95 at all high-energy neutron therapy facilities. In an effort to determine facility specific ICRU tissue to A-150 plastic kerma ratios, an experimental approach was pursued. Four low pressure proportional counters that differed in wall materials (i.e. A-150, carbon, zirconium and zirconium-oxide) were used as dosimeters and integral kerma ratios were determined directly in the clinical beam. Measurements were performed at two p(66)Be facilities: iThemba LABS near Cape Town and Fermilab near Chicago. At the iThemba facility the clinical neutron beam is routinely filtered by a flattening and hardening filter combination. The influence of beam filtration on the kerma ratio was evaluated. Using two recent gas-to-wall dose conversion factor (rm,g value) evaluations a mean ICRU tissue to A-150 plastic kerma ratio of 0.93 ± 0.05 was determined for the clinical beam at iThemba LABS. The respective value for the Fermilab beam is 0.95 ± 0.05. The experimentally determined ICRU tissue to A-150 plastic kerma ratios for the two clinical beams are in agreement with theoretical evaluations. Beam filtration reduces the kerma ratio by 3 ± 2%

  15. The smart electronic unit for precise measurement of refractive index of air in a nano-positioning stage for scanning probe microscopy (SPM).

    Czech Academy of Sciences Publication Activity Database

    Hucl, Václav; ?ížek, Martin; Buchta, Zden?k; Mikel, B?etislav; Lazar, Josef; ?íp, Ond?ej

    Ostrava : TANGER Ltd, 2012, s. 817-821. ISBN 978-80-87294-32-1. [NANOCON 2012. International Conference /4./. Brno (CZ), 23.10.2012-25.10.2012] R&D Projects: GA MPO FR-TI2/705; GA MPO FR-TI1/241; GA ?R GAP102/10/1813 Institutional support: RVO:68081731 Keywords : refractive index of air * precise measurement * laser interferometer Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  16. A Visualization Approach to Air Pollution Data Exploration—A Case Study of Air Quality Index (PM2.5) in Beijing, China

    OpenAIRE

    Huan Li; Hong Fan; Feiyue Mao

    2016-01-01

    In recent years, frequent occurrences of significant air pollution events in China have routinely caused panic and are a major topic of discussion by the public and air pollution experts in government and academia. Therefore, this study proposed an efficient visualization method to represent directly, quickly, and clearly the spatio-temporal information contained in air pollution data. Data quality check and cleansing during a preliminary visual analysis is presented in tabular form, heat mat...

  17. Human Use Index (Future)

    Data.gov (United States)

    U.S. Environmental Protection Agency — Human land uses may have major impacts on ecosystems, affecting biodiversity, habitat, air and water quality. The human use index (also known as U-index) is the...

  18. Human Use Index

    Data.gov (United States)

    U.S. Environmental Protection Agency — Human land uses may have major impacts on ecosystems, affecting biodiversity, habitat, air and water quality. The human use index (also known as U-index) is the...

  19. Studies on mass attenuation coefficient, mass energy absorption coefficient and kerma of some vitamins

    International Nuclear Information System (INIS)

    Highlights: ? Kerma is essential for nuclear medicine, diagnostics and radiation dosimeter. ? The values of ?m and ?e/? depends on the photon energy and chemical content of vitamins. ? New experiments should be performed to study physical parameters of biomolecules. -- Abstract: The mass attenuation coefficients for some vitamins (retinol, beta-carotene, thiamine, riboflavin, niacinamide, pantothenic acid, pyridoxine, biotin, folic acid, cyanocobalamin, ascorbic acid, cholecalciferol, alpha-tocopherol, ketamine, hesperidin) were determined experimentally and theoretically at 356.61, 661.66, 1250 and 1408.01 keV photon energies by using a NaI(Tl) scintillation detector. Also, the mass energy absorption coefficients and kerma have been calculated. The calculated values were compared with the semi-empirical values for vitamins.

  20. Studies on effective atomic number, electron density and kerma for some fatty acids and carbohydrates

    DEFF Research Database (Denmark)

    Manohara, S.R.; Hanagodimath, S.M.; Gerward, Leif

    2008-01-01

    XCom program. The significant variation of Z(eff) and N-el is due to the variations in the dominance of different interaction processes in different energy regions. The maximum values of Z(eff) and N-el are found in the low-energy range, where photoelectric absorption is the main interaction process. The...... also made with the single values of the Z(eff) and N-el provided by the program XMuDat. It is also observed that carbohydrates have a larger kerma than fatty acids in the low-energy region, where photoelectric absorption dominates. In contrast, fatty acids have a larger kerma than carbohydrates in the...

  1. Calculated neutron KERMA factors based on the LLNL ENDL data file. Volume 27

    International Nuclear Information System (INIS)

    Neutron KERMA factors calculated from the LLNL ENDL data file are tabulated for 15 composite materials and for the isotopes or elements in the ENDL file from Z = 1 to Z = 29. The incident neutron energies range from 1.882 x 10-5 to 20. MeV for the composite materials and from 1.30 x 10-9 to 20. MeV for the isotopes and elements

  2. Determination of the kerma in the neutron field produced by a fast reactor

    International Nuclear Information System (INIS)

    A description is given of the principle, method and technology to determine the tissue kerma rates of the neutron and ?-rays in a fission neutron field produced by a fast reactor with a IRM81-TE1 tissue-equivalent ionization chamber made in China and a low neutron sensitivity energy-compensated G-M counter. Meanwhile, measurements are made with a FWTIC-17A tissue-equivalent ionization chamber. The results determined with the two chambers agree well with each other

  3. A simple device for the measurement of kerma based on commercial PIN photo diodes.

    Czech Academy of Sciences Publication Activity Database

    Kushpil, Vasilij; Kushpil, Svetlana; Hu?a, Zden?k

    Cedex : EDP Sciences, 2012, s. 1-9. ISBN 978-88-7438-069-5. ISSN 2100-014X. [International Conference on Environmental Radioactivity - New Frontiers and Developments. ?ím (IT), 25.10.2010-27.10.2010] R&D Projects: GA MŠk LC07048 Institutional support: RVO:61389005 Keywords : PIN diode * kerma measurement Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders

  4. Applicability of the Environmental Relative Moldiness Index for Quantification of Residential Mold Contamination in an Air Pollution Health Effects Study

    Science.gov (United States)

    As part of the Near-Road Exposures and Effects of Urban Air Pollutants Study (NEXUS) investigating the respiratory health impacts of traffic-related air pollutants on asthmatic children in Detroit, Michigan, residential dust samples were collected to quantify mold exposure. Sett...

  5. Studies on effective atomic number, electron density and kerma for some fatty acids and carbohydrates

    DEFF Research Database (Denmark)

    Manohara, S.R.; Hanagodimath, S.M.

    2008-01-01

    The effective atomic number, Z(eff), the effective electron density, N-el, and kerma have been calculated for some fatty acids and carbohydrates for photon interaction in the extended energy range from 1 keV to 100 GeV using an accurate database of photon-interaction cross sections and the WinXCom program. The significant variation of Z(eff) and N-el is due to the variations in the dominance of different interaction processes in different energy regions. The maximum values of Z(eff) and N-el are found in the low-energy range, where photoelectric absorption is the main interaction process. The minimum values of Z(eff) and N-el are found at intermediate energies, typically 0.05 MeV kerma than fatty acids in the low-energy region, where photoelectric absorption dominates. In contrast, fatty acids have a larger kerma than carbohydrates in the MeV range, where Compton scattering is the main interaction process.

  6. Measurement of air-refractive-index fluctuation from frequency change using a phase modulation homodyne interferometer and an external cavity laser diode

    International Nuclear Information System (INIS)

    We present a method for air-refractive-index (nair) fluctuation measurement using a laser interferometer. The method is based on a combination of a phase modulation homodyne interferometer (PMHI), an external cavity laser diode (ECLD) and an ultralow thermal expansion material (ULTEM). The PMHI utilizes a Michelson interferometer which is constructed on the ULTEM plate under the condition of an air temperature fluctuation of less than 10 mK, so that the optical path change or the air-refractive-index fluctuation (?nair) caused by the thermal disturbance can be neglected. Meanwhile, the ECLD is controlled by adjusting its frequency to track some of the dark fringes of the interferometer, so that ?nair can be derived from the ECLD frequency change. The uncertainty of the ?nair measurement in the experiment is of 10?8 order. However, it will be possible to decrease the uncertainty to 10?9 or less if the signal-to-noise ratio (SNR) of the control system is improved

  7. Calibration of dosimeters used in diagnostic radiology in terms of air kerma rate

    International Nuclear Information System (INIS)

    This study was performed to determine IEC reference radiation beam quality for calibrating dosimeters used in diagnostic radiology. Additional filtration required to establish certain IEC quality was estimated from beam transmission measurements using Al absorbers. The experiment was carried out using medical x-ray equipment at Neelain Medical Center, Khartoum. The required added filtration thickness required to establish RQA quality was estimated according to the the method described in the IEC standard. The required filtration was estimated for each of radiation quality (40, 60, 80, 100, 120,) kV. Result showed the maximum deviation of 2.3%, for the half value-layers, which complied with the standard requirement of 3%, the additional filtration required for the RQA qualities was found to as follows: 1.2 mmAL (RQA2, 40 kV), 11.0 mmAL (RQA3, 60 kV), 20.7 mmAL ( RQA4, 80 kV), 29.5 mmAL (RQA5, 100 kV) and 33.0 mmAL (AQA6, 120 kV), those qualities recommended to be applied to calibration of the diagnostic radiology measurements instruments in Sudan.(Author)

  8. Doses monitoring in radiology: calibration of air kerma-area product (PKA meters

    Directory of Open Access Journals (Sweden)

    Ricardo Andrade Terini

    2013-12-01

    Full Text Available Objective The authors have sought to study the calibration of a clinical PKA meter (Diamentor E2 and a calibrator for clinical meters (PDC in the Laboratory of Ionizing Radiation Metrology at Instituto de Energia e Ambiente - Universidade de São Paulo. Materials and Methods Different qualities of both incident and transmitted beams were utilized in conditions similar to a clinical setting, analyzing the influence from the reference dosimeter, from the distance between meters, from the filtration and from the average beam energy. Calibrations were performed directly against a standard 30 cm3 cylindrical chamber or a parallel-plate monitor chamber, and indirectly against the PDC meter. Results The lowest energy dependence was observed for transmitted beams. The cross calibration between the Diamentor E2 and the PDC meters, and the PDC presented the greatest propagation of uncertainties. Conclusion The calibration coefficient of the PDC meter showed to be more stable with voltage, while the Diamentor E2 calibration coefficient was more variable. On the other hand, the PDC meter presented greater uncertainty in readings (5.0% than with the use of the monitor chamber (3.5% as a reference.

  9. Verification of traceability and backscattering in surface entrance air kerma measurements with detector type ionizing chamber

    International Nuclear Information System (INIS)

    Measurements of doses in radiology services by ionizing chambers are easier than those made by TLD, however the protocols for measurements differ regarding the calibration. The objectives were to verify the traceability in the measures of ESAK corrected by the inverse square law, due to the difference in position between the source and IC and the influence of the backscattered radiation in bringing the detector to the table. Was defined a procedure practiced by the radiological services and designed experimental arrangements for the same technique. Was noted that the approximation of the detector to the table generated a significant backscattered. (author)

  10. The photon fluence non-uniformity correction for air kerma near Cs-137 brachytherapy sources

    Science.gov (United States)

    Rodríguez, M. L.; de Almeida, C. E.

    2004-05-01

    The use of brachytherapy sources in radiation oncology requires their proper calibration to guarantee the correctness of the dose delivered to the treatment volume of a patient. One of the elements to take into account in the dose calculation formalism is the non-uniformity of the photon fluence due to the beam divergence that causes a steep dose gradient near the source. The correction factors for this phenomenon have been usually evaluated by the two theories available, both of which were conceived only for point sources. This work presents the Monte Carlo assessment of the non-uniformity correction factors for a Cs-137 linear source and a Farmer-type ionization chamber. The results have clearly demonstrated that for linear sources there are some important differences among the values obtained from different calculation models, especially at short distances from the source. The use of experimental values for each specific source geometry is recommended in order to assess the non-uniformity factors for linear sources in clinical situations that require special dose calculations or when the correctness of treatment planning software is verified during the acceptance tests.

  11. An EGSnrc investigation of cavity theory for ion chambers measuring air kerma

    International Nuclear Information System (INIS)

    The EGSnrc system is used to compare the response of an aluminum-walled thimble chamber to that of a graphite-walled thimble chamber for a 60Co beam. When compared to previous experimental results, the EGSnrc values of the ratios of chamber response differ by as much as 0.7% from the experiment. However, it is shown that this difference can be more than accounted for by switching from using the graphite mean excitation energy of 78 eV used in dosimetry protocols to the value of 86.8 eV suggested by more recent stopping-power experiments. This suggests that the uncertainty analysis of Monte Carlo results must be done more carefully, by taking into account uncertainties in the underlying basic data such as the electron and photon cross sections. In comparison to Spencer-Attix cavity theory for a thick-walled ion chamber, the Monte Carlo calculated values of the chamber response differ from the expected ones by 0.15% and 0.01% for the graphite and aluminum chambers, respectively, which are comparable to previously reported values for the Spencer-Attix correction factors. EGSnrc is also used to investigate the effect on the chamber response of thin dag layers on the inside of the aluminum wall. There is good agreement between the calculated and measured changes in chamber response versus the thickness of the dag. The results are compared to the predictions of the Almond-Svensson extension of cavity theory and show that the theory does not correctly predict the chamber response in the presence of thin dag layers. This finding is in agreement with previously reported experimental results. It is demonstrated that the values of ?, the fraction of ionizations in the gas arising from electrons generated in the dag layer, used in the theory, are not the source of the disagreement

  12. National air toxics information clearinghouse: Bibliography of selected reports and federal register notices related to air toxics. Index, 1992. Final report

    International Nuclear Information System (INIS)

    The purpose of the bibliography is to provide State and local agencies with citations to report and Federal Register notices useful to them in developing and operating air toxics control programs. The reports selected for this bibliography were published by the following agencies: U.S. EPA, NAS, NCI, NIEHS, NTP, NIOSH, ATSDR, CPSC, and WHO, including the International Agency for Research on Cancer. Relevant reports published by various State and local agencies are also included in this edition. The edition of the bibliography updates the cumulative bibliography previously published by the National Air Toxics Information Clearinghouse, Bibliography of Selected Reports and Federal Register Notices Related to Air Toxics, July 1991. The citations selected for this year were compiled from sources available through January 31, 1992

  13. Determination of mass attenuation coefficients, effective atomic and electron numbers, mean free paths and kermas for PbO, barite and some boron ores

    Energy Technology Data Exchange (ETDEWEB)

    Un, A., E-mail: ademun25@yahoo.com [Agri Ibrahim Cecen University, Faculty of Arts and Sciences, Department of Physics, 04100 Agri (Turkey); Sahin, Y. [Atatuerk University, Faculty of Sciences, Department of Physics, 25240 Erzurum (Turkey)

    2011-07-01

    The total mass attenuation coefficients, {mu}{sub m}, for PbO, barite, colemanite, tincal and ulexite were determined at 80.1, 302.9, 356.0, 661.7 and 1250.0 keV photon energies by using NaI (Tl) scintillation detector. Effective atomic number, Z{sub eff}, effective electron number, N{sub eff}, total atomic cross-section, {sigma}{sub t}, total electronic cross-section, {sigma}{sub e}, mean free path, mfp, and kerma relative to air were determined experimentally and theoretically. The theoretical mass attenuation coefficients were estimated using mixture rule. The calculated values were compared with the experimental values for all samples.

  14. Obtención de un índice de riesgo de erosión eólica y su aplicación en la provincia de Buenos Aires, Argentina Erosion risk index attainment and its application in the Buenos Aires province, Argentina

    Directory of Open Access Journals (Sweden)

    Susana Goldberg

    2004-12-01

    Full Text Available En este trabajo se propone un índice climático para estimar el riesgo de ocurrencia de erosión eólica basado en las leyes físicas que cuantifican el efecto de la agresión del medio (turbulencia atmosférica sobre la resistencia del sistema (textura del suelo. Este indicador es obtenido en función de observaciones meteorológicas estándar a partir de un modelo que incluye la alteración del perfil vertical del viento ocasionada por la presencia de partículas de suelo en el aire y es expresado en términos de la probabilidad de que la potencia del viento supere las condiciones umbrales para el comienzo del proceso. Si bien el índice fue obtenido para suelo seco y desnudo, la metodología permite avanzar hacia un modelo de evaluación de riesgo más general, si se determinan previamente los valores de velocidad de fricción umbral que corresponden a distintas condiciones que afectan la resistencia del suelo tales como la humedad del suelo, el contenido de materia orgánica, cobertura y uso de la tierra. Este modelo ha sido utilizado para evaluar la distribución espacial del riesgo de erosión eólica en la Provincia de Buenos Aires, Argentina.This paper proposes a climatic index to estimate the wind erosion risk based upon physical laws that quantify the effect of environment's aggression (atmospheric turbulence on system resistance (soil texture. This index is obtained as a function of standard meteorological observations including the alteration of the wind profile produced by the presence of soil particles in the air and it is expressed in terms of the probability for the wind power to exceed the threshold conditions. Although this index was obtained for dry and bare soil, it may mean an advance towards a more general model for risk evaluation if other factors intervening in soil resistance, such as soil humidity, organic material content, land cover and use are included. This model has been used to evaluate the spatial distribution of the wind erosion risk in Buenos Aires Province, Argentina.

  15. Doses monitoring in radiology: calibration of air kerma-area product (PKA) meters / Monitoração de doses em radiologia: a calibração de medidores do produto kerma-área (PKA)

    Scientific Electronic Library Online (English)

    Ricardo Andrade, Terini; Maria Carolina de Santana, Campelo; Jose Neres de, Almeida Jr.; Silvio Bruni, Herdade; Marco Aurelio Guedes, Pereira.

    2013-12-01

    Full Text Available Objective The authors have sought to study the calibration of a clinical PKA meter (Diamentor E2) and a calibrator for clinical meters (PDC) in the Laboratory of Ionizing Radiation Metrology at Instituto de Energia e Ambiente - Universidade de São Paulo. Materials and Methods Different qualities [...] of both incident and transmitted beams were utilized in conditions similar to a clinical setting, analyzing the influence from the reference dosimeter, from the distance between meters, from the filtration and from the average beam energy. Calibrations were performed directly against a standard 30 cm3 cylindrical chamber or a parallel-plate monitor chamber, and indirectly against the PDC meter. Results The lowest energy dependence was observed for transmitted beams. The cross calibration between the Diamentor E2 and the PDC meters, and the PDC presented the greatest propagation of uncertainties. Conclusion The calibration coefficient of the PDC meter showed to be more stable with voltage, while the Diamentor E2 calibration coefficient was more variable. On the other hand, the PDC meter presented greater uncertainty in readings (5.0%) than with the use of the monitor chamber (3.5%) as a reference.

  16. Uncontrolled combustion of shredded tires in a landfill - Part 2: Population exposure, public health response, and an air quality index for urban fires

    Science.gov (United States)

    Singh, Ashish; Spak, Scott N.; Stone, Elizabeth A.; Downard, Jared; Bullard, Robert L.; Pooley, Mark; Kostle, Pamela A.; Mainprize, Matthew W.; Wichman, Michael D.; Peters, Thomas M.; Beardsley, Douglas; Stanier, Charles O.

    2015-03-01

    The Iowa City Landfill in eastern Iowa, United States, experienced a fire lasting 18 days in 2012, in which a drainage layer of over 1 million shredded tires burned, generating smoke that impacted the surrounding metropolitan area of 130,000 people. This emergency required air monitoring, risk assessment, dispersion modeling, and public notification. This paper quantifies the impact of the fire on local air quality and proposes a monitoring approach and an air quality index (AQI) for use in future tire fires and other urban fires. Individual fire pollutants are ranked for acute and cancer relative risks using hazard ratios, with the highest acute hazard ratios attributed to SO2, particulate matter, and aldehydes. Using a dispersion model in conjunction with the new AQI, we estimate that smoke concentrations reached unhealthy outdoor levels for sensitive groups out to distances of 3.1 km and 18 km at 24-h and 1-h average times, respectively. Modeled and measured concentrations of PM2.5 from smoke and other compounds such as VOCs and benzo[a]pyrene are presented at a range of distances and averaging times, and the corresponding cancer risks are discussed. Through reflection on the air quality response to the event, consideration of cancer and acute risks, and comparison to other tire fires, we recommend that all landfills with shredded tire liners plan for hazmat fire emergencies. A companion paper presents emission factors and detailed smoke characterization.

  17. Paediatric entrance doses from exposure index in computed radiography

    Science.gov (United States)

    Vano, E.; Martinez, D.; Fernandez, J. M.; Ordiales, J. M.; Prieto, C.; Floriano, A.; Ten, J. I.

    2008-06-01

    Over the last two years we have evaluated paediatric patient doses in projection radiography derived from exposure level (EL) in computed radiography (CR) in a large university hospital. Entrance surface air kerma (ESAK) for 3501 paediatric examinations was calculated from the EL, which is a dose index parameter related to the light emitted by the phosphor-stimulable plate, archived in the Digital Imaging and Communications in Medicine (DICOM) header of the images and automatically transferred to a database using custom-built dedicated software. Typical mean thicknesses for several age bands of paediatric patients was estimated to calculate ESAK from the EL values, using results of experimental measurements with phantoms for the typical x-ray beam qualities used in paediatric examinations. Mean/median ESAK values (in µGy) for the age bands of paediatrics. Presently, this method is the only practical approach to automatically extract parameters contained in the DICOM header, for the calculation of patient dose values for the CR modality.

  18. Importance of the neutrons kerma coefficient in the planning of Brachytherapy treatments with Cf-252 sources

    International Nuclear Information System (INIS)

    The Cf-252 is a fast neutrons emitting radioisotope by spontaneous fission that can be used as sealed source in medicine applications, industry and research. Commercially its offer sources of different sizes, compact and with a fast neutrons emission of the order of 106 n/s-?g and an energy spectra that presents respectively maxim and average energy in 2.1 MeV and 0.7 MeV. In medicine new applications are being developed for the treatment of patient with hypoxic and voluminous tumors, where the therapy with photons has not given positive results, as well as for the protocols of therapy treatment by boron neutron capture, where very small sources of Cf-252 will be used with the interstitial brachytherapy technique of high and low dose rate. In this work an analysis of how the small differences that exist in the elementary composition of 4 wicked tumors, 4 ICRU healthy tissues and 3 substitute materials of ICRU tissue used in dosimetry are presented, its generate changes in the neutrons kerma coefficient in function of the energy and consequently in the absorbed dose in the interval of 11 eV to 29 MeV. These differences can produce maximum variations of the neutron kerma coefficients ratio for En > 1 keV of the one: 15% tumor/ICRU guest healthy tissue, 12% ICRU tumor/muscle, 12% ICRU healthy tissues ICRU/ICRU muscle, 22% substitutes tissue/tumor and 22% ICRU substitutes tissue/muscle. Also, it was found that the average value of the neutrons kerma coefficient for the 4 wicked tumors is from 6% to 7% smaller that the average value for the soft tissue in the interval energy of interest for therapy with fast neutrons with En > 1 MeV. These results have a special importance during the planning process of brachytherapy treatments with sources of 252Cf, to optimize and to individualize the patients treatments. (Author)

  19. The variability in kerma output and radiation quality of medical diagnostic x-ray units

    International Nuclear Information System (INIS)

    The use of diagnostic x-ray tubes results in an increased roughness of the anode surface. This effect of tube ageing increases the inherent filtration of the x-ray tube, hereby reducing kerma output and changing radiation quality. To study this effect, used rotating anodes were collected; the surface profiles and surface roughness of 8 focal tracks were determined. The surface profiles were then used to calculate x-ray spectra using a computer code. The results indicate that an increased roughness induces an additional filtration in the tungsten anode. The roughest surface (Ra=5.22 ?m) yields a mean additional absorber thickness in direction of the x-ray beam of about 18 ?m with a corresponding loss in kerma output of about 30 % at 70 kV. The effects on mean photon energy and HVL are rather small but highest around 70 kV and lowest at 140 kV. This is due to the K-edge in the attenuation coefficients of tungsten at 69.5 keV. To study the influence of tube ageing on beam quality with clinical x-ray units, kerma measurements were made for 19 samples as to determine attenuation curves. A fit method for the determination of total filtration including the effects of anode surface deterioration was devised. The thicknesses of the tungsten layers obtained using this method vary from 2.43 ?m to 11.89 ?m with an associated surface roughness Ra from 1.5 to 4.5 ?m corresponding very well to the thicknesses of the additional absorbing layers determined for rough anodes. A determination of additional filtration in terms of an equivalent aluminium filter gave thicknesses from 0.34 to 1.72 mm aluminium. The results showed that the effects of tube ageing on the x-rays could be described by an additional filtration of aluminium. (author)

  20. Effective atomic number, electron density and kerma of gamma radiation for oxides of lanthanides

    Indian Academy of Sciences (India)

    R S Niranjan; B Rudraswamy; N Dhananjaya

    2012-03-01

    An attempt has been made to estimate the effective atomic number, electron density (0.001 to 10$^5$ MeV) and kerma (0.001 to 20 MeV) of gamma radiation for a wide range of oxides of lanthanides using mass attenuation coef?cient from WinXCom and mass energy absorption coef?cient from Hubbell and Seltzer. The values of these parameters have been found to change with energy for different oxides of lanthanides. The lanthanide oxides ?nd remarkable applications in the ?eld of medicine, biology, nuclear engineering and space technology. Nano-oxides of lanthanide ?nd applications in display and lighting industry.

  1. Air

    International Nuclear Information System (INIS)

    In recent years several regulations and standards for air quality and limits for air pollution were issued or are in preparation by the European Union, which have severe influence on the environmental monitoring and legislation in Austria. This chapter of the environmental control report of Austria gives an overview about the legal situation of air pollution control in the European Union and in specific the legal situation in Austria. It gives a comprehensive inventory of air pollution measurements for the whole area of Austria of total suspended particulates, ozone, volatile organic compounds, nitrogen oxides, sulfur dioxide, carbon monoxide, heavy metals, benzene, dioxin, polycyclic aromatic hydrocarbons and eutrophication. For each of these pollutants the measured emission values throughout Austria are given in tables and geographical charts, the environmental impact is discussed, statistical data and time series of the emission sources are given and legal regulations and measures for an effective environmental pollution control are discussed. In particular the impact of fossil-fuel power plants on the air pollution is analyzed. (a.n.)

  2. Spatial Correlations of Anomaly Time Series of AIRS Version-6 Land Surface Skin Temperatures with the Nino-4 Index

    Science.gov (United States)

    Susskind, Joel; Lee, Jae N.; Iredell, Lena

    2013-01-01

    The AIRS Science Team Version-6 data set is a valuable resource for meteorological studies. Quality Controlled earth's surface skin temperatures are produced on a 45 km x 45 km spatial scale under most cloud cover conditions. The same retrieval algorithm is used for all surface types under all conditions. This study used eleven years of AIRS monthly mean surface skin temperature and cloud cover products to show that land surface skin temperatures have decreased significantly in some areas and increased significantly in other areas over the period September 2002 through August 2013. These changes occurred primarily at 1:30 PM but not at 1:30 AM. Cooling land areas contained corresponding increases in cloud cover over this time period, with the reverse being true for warming land areas. The cloud cover anomaly patterns for a given month are affected significantly by El Nino/La Nina activity, and anomalies in cloud cover are a driving force behind anomalies in land surface skin temperature.

  3. W/sub n/ and neutron kerma for methane-based tissue-equivalent gas

    International Nuclear Information System (INIS)

    The principal dosimeter used to determine the absorbed dose of neutrons employed in radiobiology and radiotherapy is the homogeneous tissue-equivalent (TE) ionization chamber. A methane-based TE gas mixture is most commonly used in the chamber cavity. This instrument is used to measure the charge liberated in the gas by the secondary charged particles set in motion by the neutrons. Conversion of this charge to absorbed dose requires knowledge of W/sub n/, the mean energy expended to form an ion pair in the gas by the initial spectra of secondary particles produced by the neutrons. The computation of W/sub n/ requires that secondary charged particle spectra calculated from neutron interaction cross sections and energetics be employed for each neutron energy used, as is done in this report. The computation of W/sub n/ also requires that experimental data on W for each type of secondary charged particle be available. Revision puts them in sufficient agreement with the other data that they are here given equal weight in the evaluations of W. Further, this report discusses the relative kermas contributed by the various types of charged particles. By combining computed charged particle spectra with the evaluations of W, the number of ion pairs produced in the gas by each type of charged particle is derived, from which W/sub n/ is computed as the quotient of the total kerma by the total number of ion pairs

  4. Scattering study at free air ionization chamber diaphragm

    International Nuclear Information System (INIS)

    The maim of this work consisted in the assessment of the correction factor for air kerma, due to scattered radiation in the diaphragm of the free-air ionization chamber model 481. LNMRl measurements were made to acquire x-ray spectra corresponding to the Qualities RQR-M, described in IEC 61627 standards (2005). These spectra were used as input data in the MC simulations. The operational range of energy spectra provide up to 35 keV. This energy range is typically used in diagnostic radiology, although there is not primary standard for air kerma. The determination of this factor is a fundamental process in the primary standardization of the air kerma. These factors were obtained by computer simulation using the Penelope code. The results are kRQR-M1=0,9946, kRQR-M2=0,9932, kRQR-M3=0,9978 and kRQR-M4=0,9885; with uncertainties of 0,007 and coverage factor equal to 2. lt can be concluded that, with respect to the diaphragm, the chamber can be used in the primary standard of air kerma. (author)

  5. Assessing the use of the Air Quality Health Index by vulnerable populations in a 'low-risk' region: A pilot study.

    Science.gov (United States)

    Spurr, K; Pendergast, N; MacDonald, S

    2014-01-01

    Several studies have shown a relationship between exposure to outdoor air pollution and adverse health effects, and that people with specific chronic diseases appear to be particularly vulnerable. An important opportunity exists for respiratory therapists to inform at-risk clients, especially those with lung disease, about outdoor air pollution and its role in self-management. The Air Quality Health Index (AQHI), a national program led by Health Canada and Environment Canada, is intended to inform individuals about the level of health risk associated with air pollution in Canadian communities, and to provide a tool to manage those risks. The main purpose of the present study was to assess the use of the AQHI by vulnerable populations in a 'low-risk' (AQHI ?3) region. The specific objectives were: to develop and evaluate an AQHI education strategy; to investigate whether awareness of the AQHI impacts self-management in vulnerable populations in low-risk regions; and to identify enabling factors and/or barriers concerning use of the AQHI by both health care professionals and their patients. A pilot study was conducted using a small convenience sample of clients/patients and educators at respiratory clinics across Nova Scotia. A short educational activity on the utility and application of the AQHI was incorporated into their regular disease management plans and surveys were administered pre- and posteducational intervention. Twenty-one clients from three respiratory clinics consented to participate in the study and received the AQHI education program. Using a Wilcoxon signed-rank test with paired data, five of six survey questions had statistically significant changes in response to pre- and posteducation. Some common themes that emerged from qualitative data collected included: limited access to the Internet; lack of its reporting in the media; confusion with other indexes; and relevancy of the AQHI in Nova Scotia, a 'low-risk' region. An AQHI educational program improved knowledge and use of the AQHI reported by respiratory clinic patients. Respiratory educators reported the AQHI education program was relatively simple to implement into their chronic disease education plan. A larger-scale study involving participants residing in a moderate- or high-risk region is recommended. PMID:26078611

  6. Ellipsometric study of molecular orientations of Thermomyces lanuginosus lipase at the air-water interface by simultaneous determination of refractive index and thickness.

    Science.gov (United States)

    Muth, Marco; Schmid, Reiner P; Schnitzlein, Klaus

    2016-04-01

    Ellipsometric studies of very thin organic films suffer from the low refractive index contrast between layer and bulk substrate. We demonstrate that null ellipsometry can not only provide detailed information about the adsorption kinetics and surface excess values, but in addition on layer thicknesses with submonolayer resolution of a lipase from Thermomyces lanuginosus at the air-water interface. While measuring very close to the Brewster angle, refractive indices and layer-thicknesses can both be determined with a precision that is sufficiently high to make conclusions on the density and orientation of the molecules at the interface. The orientation was found to be concentration- and pH value-dependent. At the isoelectric point, the lipase was almost vertically oriented with respect to the surface, while for pure distilled water and low lipase concentration a rather horizontal alignment was found. Further experiments, varying the size of the interfacial area in a Langmuir trough, confirm the different layer structures. PMID:26735895

  7. High NDVI and Potential Canopy Photosynthesis of South American Subtropical Forests despite Seasonal Changes in Leaf Area Index and Air Temperature

    Directory of Open Access Journals (Sweden)

    Piedad M. Cristiano

    2014-02-01

    Full Text Available The canopy photosynthesis and carbon balance of the subtropical forests are not well studied compared to temperate and tropical forest ecosystems. The main objective of this study was to assess the seasonal dynamics of Normalized Difference Vegetation Index (NDVI and potential canopy photosynthesis in relation to seasonal changes in leaf area index (LAI, chlorophyll concentration, and air temperatures of NE Argentina subtropical forests throughout the year. We included in the analysis several tree plantations (Pinus, Eucalyptus and Araucaria species that are known to have high productivity. Field studies in native forests and tree plantations were conducted; stem growth rates, LAI and leaf chlorophyll concentration were measured. MODIS satellite-derived LAI (1 km SIN Grid and NDVI (250m SIN Grid from February 2000 to 2012 were used as a proxy of seasonal dynamics of potential photosynthetic activity at the stand level. The remote sensing LAI of the subtropical forests decreased every year from 6 to 5 during the cold season, similar to field LAI measurements, when temperatures were 10 °C lower than during the summer. The yearly maximum NDVI values were observed during a few months in autumn and spring (March through May and November, respectively because high and low air temperatures may have a small detrimental effect on photosynthetic activity during both the warm and the cold seasons. Leaf chlorophyll concentration was higher during the cold season than the warm season which may have a compensatory effect on the seasonal variation of the NDVI values. The NDVI of the subtropical forest stands remained high and fairly constant throughout the year (the intra-annual coefficient of variation was 1.9%, and were comparable to the values of high-yield tree plantations. These results suggest that the humid subtropical forests in NE Argentina potentially could maintain high canopy photosynthetic activity throughout the year and thus this ecosystem may be a large carbon sink.

  8. Relationship between maternal pre-pregnancy body mass index, gestational weight gain and childhood fatness at 6-7 years by air displacement plethysmography.

    Science.gov (United States)

    Castillo, Helen; Santos, Iná S; Matijasevich, Alicia

    2015-10-01

    This study aims to investigate the effect of maternal pre-pregnancy body mass index (BMI) and gestational weight gain (GWG) on offspring body composition. In this prospective cohort study, offspring body composition at 6 years of age was obtained through air displacement plethysmography. Linear regression was used to obtain crude and adjusted coefficients. Information regarding offspring body composition and maternal pre-pregnancy BMI was available for 3156 children and on offspring body composition and GWG for 3129 children. There was a direct association of maternal pre-pregnancy BMI and GWG with offspring's fat mass (FM), fat-free mass (FFM), fat mass index (FMI), fat-free mass index (FFMI) and body fat percent (BF%) in crude and adjusted analyses. After adjustment for co-variables, for each kg?m(-2) of maternal pre-pregnancy BMI increase, there was a mean increment of 0.13?kg in the offspring FFM, 0.06?kg?m(-2) in FFMI, 0.11?kg in FM, 0.07?kg?m(-2) in FMI and 0.18% in BF%. For each kilogram of maternal GWG increase, there was a mean increment of 0.08?kg in offspring's FM, 0.05?kg?m(-2) in FMI, 0.04?kg in FFM, 0.01?kg?m(-2) in FFMI and 0.18 % in BF%. Mothers with a higher pre-pregnancy BMI or GWG tend to have children with greater adiposity at age 6 years. Fetal overnutrition is more likely among mothers with greater BMI during pregnancy; as a consequence, it can accelerate the childhood obesity epidemic. PMID:25850519

  9. Air pollution reduction with respect to the conversion of biomass into electricity and heat. Emission and cost indexes

    International Nuclear Information System (INIS)

    Although biomass conversion is considered to be a CO2-free method of producing electricity and heat other emissions have to be taken into account: SO2, NOx, HCl, HF, Hg, Cd, dusts, etc. The aim of the study on the title subject is to support the Dutch Ministry of Housing, Planning and Environment (VROM) in the determination of feasible emission standards for bioconversion installations. The Centre for Energy conservation and clean technology (CE) compiled information on the costs for flue gas purification for different degrees of purification. Because of the fact that the composition of flue gases strongly depends on the biomass flow and the applied conversion technique, both biomass flows and conversion techniques must be distinguished. The following biomass conversion techniques were studied: large-scale combustion of wood wastes and sludges, large-scale gasification of wood wastes, cocombustion of wood wastes and sludges, small-scale combustion of wood wastes and chicken manure, small-scale gasification of wood wastes, and fermentation of wastes from vegetables, fruits and gardens. For each combination it is determined what the emissions are in case of a minimal flue gas purification, what the emissions are and how much additional costs are involved in case the regulations in the BLA (decree on air pollution of waste incineration) are taken into account, and what the emissions are and how much additional costs are involved for a number of levels in between the two fore-mentioned cases. refs

  10. Neutron spectra and neutron kerma derived from activation and fission detector measurements in a d + T neutron therapy beam

    International Nuclear Information System (INIS)

    Neutron spectra at different positions in a phantom have been derived from activation foil and fission counter measurements for the collimated beam of the Amsterdam d + T fast-neutron therapy facility. The spectra show that the fraction of lower-energy neutrons increases with increasing depth in the phantom as well as with increasing distance from the central axis of the beam. Calculation of the ratios of kerma values in tissue and tissue-equivalent (TE) plastic and of Wsub(N) values for the spectra at five positions in the phantom, showed that the variations in these quantities are less than 0.5%. Kerma values have been derived from the neutron spectra and from the fission counter measurements separately. These neutron kerma values were compared with the neutron absorbed dose values derived from combined TE ionisation chamber and GM counter measurements. The dose values have been obtained applying recommendations given in the European protocol for neutron dosimetry for external beam therapy. At 50 mm and 100 mm depth along the central axis of the beam in the phantom, the agreement between the three methods was within 2%. In the penumbra region a maximum difference of about 7% has been observed between the three methods. The contribution from thermal neutrons to the total kerma is less than 1% in the beam as well as in the penumbra. (author)

  11. Tissue kerma vs distance relationships for initial nuclear radiation from the atomic devices detonated over Hiroshima and Nagasaki

    International Nuclear Information System (INIS)

    Initial nuclear radiation is comprised of prompt neutrons and prompt primary gammas from an exploding nuclear device, prompt secondary gammas produced by neutron interactions in the environment, and delayed neutrons and delayed fission-product gammas from the fireball formed after the nuclear device explodes. These various components must all be considered in establishing tissue kerma vs distance relationships which describe the decrease of initial nuclear radiation with distance in Hiroshima and in Nagasaki. The tissue kerma at ground evel from delayed fission-product gammas and delayed neutrons was investigated using the NUIDEA code developed by Science Applications, Inc. This code incorporates very detailed models which can take into account such features as the rise of the fireball, the rapid radioactive decay of fission products in it, and the perturbation of the atmosphere by the explosion. Tissue kerma vs distance relationships obtained by summing results of these current state-of-the-art calculations will be discussed. Our results clearly show that the prompt secondary gammas and delayed fission-product gammas are the dominant components of total tissue kerma from initial nuclear radiation in the cases of the atomic (or pure-fission) devices detonated over Hiroshima and Nagasaki

  12. Evaluation of Kerma rate in the skin entrance in interventional procedures guided by fluoroscopy

    International Nuclear Information System (INIS)

    Interventional therapeutic procedures guided by fluoroscopy are responsible for delayed exposure to radiation of professionals and patients. The technology employed on generation of the pulsed fluoroscopy can be an important tool of protection used for reducing the exposure time. It generates constant width and varied frequency pulse or width pulse or varied frequency for a constant frequency. The typical doses into the skin and its relationship with the quality of the images in the various technical and operational conditions should be known by the professionals so that they can optimize them. Generated radiation doses were evaluated using the Toshiba Infinitix equipment used in invasive cardiology procedures and electrophysiological studies through the Kerma rate at the entrance of the patient's skin measured throughout the year of 2004. With these information shall be set out the criteria for the decision of the technical-operational conditions that allow minimizing of dose

  13. Evaluation of skin entry kerma in radiological examinations at the Hospital de Clinicas, Parana, Brazil

    International Nuclear Information System (INIS)

    This paper evaluates the skin entry dose of pediatric and adults patients when submitted to radiological examinations at the Hospital de Clinicas do Parana, Brazil, as part integrate of the data assessment of International Atomic Energy Agency (IAEA) for Latin America. It was performed measurements of dose for evaluation of skin entry kerma in pediatric patients in thorax AP/PA examinations, adults of thorax in AP/PA, cranio caudal mammography and median lateral and patients of computerized tomography in examination of head, thorax and abdomen. The obtained data demonstrate the necessity of verification of diagnostic analysis standards. The great value amplitudes demonstrate the incompatibility of examination executions with those recommended by the literature. The dose values presented partially inside the range recommended and the other over the expected for the due examination when compared with the literature

  14. Results of comparative measurements of neutron tissue kerma and photon dose by emergency dosemeters

    International Nuclear Information System (INIS)

    The comparative study of the characteristics of the DINA dosemeter and silicon dosemeter, as well as the IKS-A thermoluminescent dosemeter and the GO-32 photoluminescent dosemeter is performed. The measurements were carried out at the BR-10, RF-GS, BR-1-21, BR-1-22 and IBR-30 reactos as well as at accelerators generating 14-16 MeV neutrons. The data obtained have shown that the measurement error for neutron tissue kerma using the DINA dosemeter can exceed 50%, for the silicon dosemeter it is considerably lower and equal to ±18%. The GO-32 dosemeter used for measuring the photon radiation dose has the sensitivity to neutrons of 0.02-0.05 radiation dose has the sensitivity to neutrons of 0.02-0.05

  15. HUMAN USE INDEX (FUTURE)

    Science.gov (United States)

    Human land uses may have major impacts on ecosystems, affecting biodiversity, habitat, air and water quality. The human use index (also known as U-index) is the percentage of human land use in an area, including agriculture, urban and suburban development, and mining. Low values ...

  16. HUMAN USE INDEX

    Science.gov (United States)

    Human land uses may have major impacts on ecosystems, affecting biodiversity, habitat, air and water quality. The human use index (also known as U-index) is the percentage of human land use in an area, including agriculture, urban and suburban development, and mining. Low values ...

  17. 2014 Environmental Performance Index (EPI)

    Data.gov (United States)

    National Aeronautics and Space Administration — The 2014 Environmental Performance Index (EPI) ranks 178 countries on 20 performance indicators in the following 9 policy categories: health impacts, air quality,...

  18. Humidity coefficient correction in the calculation equations of air refractive index by He-Ne laser based on phase step interferometry.

    Science.gov (United States)

    Chen, Qianghua; Liu, Jinghai; He, Yongxi; Luo, Huifu; Luo, Jun; Wang, Feng

    2015-02-10

    The refractive index of air (RIA) is an important parameter in precision measurement. The revisions to Edlen's equations by Boensch and Potulski [Metrologia 35, 133 (1998)] are mostly used to calculate the RIA at present. Since the humidity correction coefficients in the formulas were performed with four wavelengths of a Cd(114) lamp (644.0, 508.7, 480.1, and 467.9 nm) and at the temperature range of 19.6°C-20.1°C, the application is restricted when an He-Ne laser is used as the light source, which is mostly applied in optical precision measurement, and the environmental temperature is far away from 20°C as well. To solve this problem, a measurement system based on phase step interferometry for measuring the effect of the humidity to the RIA is presented, and a corresponding humidity correction equation is derived. The analysis and comparison results show that the uncertainty of the presented equation is better than that of Boensch and Potulski's. It is more suitable in present precision measurements by He-Ne laser, and the application temperature range extends to 14.6°C-24.0°C as well. PMID:25968028

  19. Fully-automated estimation of actual to potential evapotranspiration in the Everglades using Landsat and air temperature data as inputs to the Vegetation Index-Temperature Trapezoid method

    Science.gov (United States)

    Yagci, A. L.; Jones, J. W.

    2014-12-01

    While the greater Everglades contains a vast wetland, evapotranspiration (ET) is a major source of water "loss" from the system. Like other ecosystems, the Everglades is vulnerable to drought. Everglades restoration science and resource management requires information on the spatial and temporal distribution of ET. We developed a fully-automated ET model using the Vegetation Index-Temperature Trapezoid concept. The model was tested and evaluated against in-situ ET observations collected at the Shark River Slough Mangrove Forest eddy-covariance tower in Everglades National Park (Sitename / FLUXNET ID: Florida Everglades Shark River Slough Mangrove Forest / US-Skr). It uses Landsat Surface Reflectance Climate Data from Landsat 5, and Landsat 5 thermal and air temperature data from the Daily Gridded Surface Dataset to output the ratio of actual evapotranspiration (AET) and potential evapotranspiration (PET). When multiplied with a PET estimate, this output can be used to estimate ET at high spatial resolution. Furthermore, it can be used to downscale coarse resolution ET and PET products. Two example outputs covering the agricultural lands north of the major Everglades wetlands extracted from two different dates are shown below along with a National Land Cover Database image from 2011. The irrigated and non-irrigated farms are easily distinguishable from the background (i.e., natural land covers). Open water retained the highest AET/PET ratio. Wetlands had a higher AET/PET ratio than farmlands. The main challenge in this study area is prolonged cloudiness during the growing season.

  20. 40 CFR 58.50 - Index reporting.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 5 2010-07-01 2010-07-01 false Index reporting. 58.50 Section 58.50 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) AMBIENT AIR QUALITY SURVEILLANCE Air Quality Index Reporting § 58.50 Index reporting. (a) The State or...

  1. Patient Specific Kerma Area Product as an Exposure Estimator in Computed Tomography: The Concept and Typical Values

    International Nuclear Information System (INIS)

    Monitoring of exposure levels in computed tomography is important from the radiation safety point of view. In this paper, the concept suggested by Huda of using the patient specific kerma area product as an exposure estimator is extended by providing both a rigorous definition of this quantity and a method for its evaluation. The method was demonstrated on an axial scan of the standard CT dosimetry head phantom taken with a Siemens Somatom Open CT scanner. The resulting patient specific kerma area product was 0.25 Gy cm2 for the X ray tube voltage of 120 kV, tube current of 100 mA, scanning time of 1 s, and beam width at the isocentre of 1.2 cm. To implement this method, the CT scanner must be equipped with a KAP meter, and the calculation procedure must be added to the scanner's software. Alternatively, the patient specific kerma area product can be calculated by the CT scanner without using a KAP meter. In this case, however, the extra safety feature provided by the direct monitoring of the X ray beam by the KAP meter is lost. (author)

  2. ZZ KAOS/LIB-V, Kerma Factors, Nuclear Response Function Library for Fission, Fusion

    International Nuclear Information System (INIS)

    Description of program or function: Format: FIDO; Number of groups: 174 neutron groups; Nuclides: H, He, Li, Be, B, C, N, O, F, Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo, Hf, Ta, W, Pb, Bi, Th, Pa, U, Np, Pu, Am. Origin: ENDF/B-V, JENDL-2; Weighting spectrum: VITAMIN-E weighting function. The library includes neutron kerma factors, gas production, tritium breeding cross sections, and all important reaction cross sections for a large number of materials of interest in fission and fusion systems. The library was generated with the KAOS-V code (PSR-306) employing basic nuclear data from ENDF/B-V. Auxiliary nuclear data bases, such as the Japanese library JENDL-2, were used as a source of isotopic cross sections when these data are not provided in ENDF/B-V files for a natural element. KAOS/LIB-V employs the VITAMIN-E weighting function and energy group structure of 174 neutron groups. The library is designed for fusion and fission applications

  3. W/sub n/ and neutron kerma for methane-based tissue-equilvalent gas

    International Nuclear Information System (INIS)

    Homogeneous tissue-equivalent ionization chambers containing a methane-based gas mixture are widely used to determine the absorbed dose of neutrons employed in radiobiology and radiotherapy. Conversion of the measured ionization charge to the absorbed dose requires knowledge of W/sub n, the mean energy expended to form an ion pair in the gas by the initial spectra of secondary charged particles produced by the neutrons. This report discusses the computed charged particle spectra in the gas and the relative kermas contributed by the various types of charged particles. These spectra are combined with an evaluation of the available experimental data on W for the secondary particles to compute W/sub n/ as a function of neutron energy. Over the energy range of 0.1 to 20 MeV, W/sub n/ was found to vary from 32.8 to 31.0 eV, respectively, including sharp changes in W/sub n/ due to large resonances in the energy transferred to carbon and oxygen. It is recommended that the data presented be used to evaluate W/sub n/ for each neutron spectrum for which accurate dosimetry is required. A single value of 31.9 +- 0.9 eV is recommended for less demanding applications or when neutron spectra are poorly known

  4. Comments on 'Direct determination of kerma for a d(48.5)+Be therapy beam'

    International Nuclear Information System (INIS)

    In their paper, the authors comment on the differences between their results and ours, which we obtained in a p(62 MeV)+Be beam using Al and Al2O3 with a single anode wire. However, rather than focusing, as they did, on the differences between these two sets of measurements, it would, perhaps, be more appropriate to highlight the similarities, since these are, to the best of my knowledge, the only two published datasets for this kind of oxygen and carbon in fast neutron therapy beams. Comparing their figure 4 with our figure 8, both sets of measurements show an increased proton dose component for oxygen compared with carbon (at approximately 100 keV ?m and 100 MeV cm2g). Both sets of measurements also show a greater proportion of high LET events for oxygen compared with carbon, and the higher LET of the heavy recoil edge in the oxygen measurement is also evident in both cases. The main difference between the two sets of measurements, as Binns et al point out, lies in the relative magnitude of the alpha component: for both oxygen and carbon their alpha to proton ratio is greater than ours. However, it is the similarity in shape of the two datasets which provides validation of the experimental routes used to determine elemental kerma in neutron therapy beams. Letter-to-the-editor

  5. Index Bioclimatic "Wind-Chill"

    Directory of Open Access Journals (Sweden)

    Teodoreanu Elena

    2015-05-01

    Full Text Available This paper presents an important bioclimatic index which shows the influence of wind on the human body thermoregulation. When the air temperature is high, the wind increases thermal comfort. But more important for the body is the wind when the air temperature is low. When the air temperature is lower and wind speed higher, the human body is threatening to freeze faster. Cold wind index is used in Canada, USA, Russia (temperature "equivalent" to the facial skin etc., in the weather forecast every day in the cold season. The index can be used and for bioclimatic regionalization, in the form of skin temperature index.

  6. Use of an index to reflect the aggregate burden of long-term exposure to criteria air pollutants in the United States.

    OpenAIRE

    Kyle, Amy D.; Woodruff, Tracey J.; Buffler, Patricia A; Davis, Devra L

    2002-01-01

    Air pollution control in the United States for five common pollutants--particulate matter, ground-level ozone, sulfur dioxide, nitrogen dioxide, and carbon monoxide--is based partly on the attainment of ambient air quality standards that represent a level of air pollution regarded as safe. Regulatory and health agencies often focus on whether standards for short periods are attained; the number of days that standards are exceeded is used to track progress. Efforts to explain air pollution to ...

  7. Development of an Aggregate Air Quality Index Using a PCA-Based Method: A Case Study of the US Transportation Sector

    OpenAIRE

    Jaesung Choi; Yong Shin Park; Ju Dong Park

    2015-01-01

    For the past couple of decades, the transportation sector has made efforts to preserve and improve air quality for public health and sustainable growth between current and future generations. An easily understandable tool to measure the level of air pollution in the transportation sector by considering multiple air pollutants together might raise awareness about clean air to the public, practitioners, state policy planners, and the government. For this reason, this study develops an aggregate...

  8. The tree BVOC index

    International Nuclear Information System (INIS)

    Urban trees can produce a number of benefits, among them improved air quality. Biogenic volatile organic compounds (BVOCs) emitted by some species are ozone precursors. Modifying future tree planting to favor lower-emitting species can reduce these emissions and aid air management districts in meeting federally mandated emissions reductions for these compounds. Changes in BVOC emissions are calculated as the result of transitioning to a lower-emitting species mix in future planting. A simplified method for calculating the emissions reduction and a Tree BVOC index based on the calculated reduction is described. An example illustrates the use of the index as a tool for implementation and monitoring of a tree program designed to reduce BVOC emissions as a control measure being developed as part of the State Implementation Plan (SIP) for the Sacramento Federal Nonattainment Area. - Highlights: ? A Tree BVOC index based on reduced emissions from low emitting trees is described. ? An example illustrates use of the index as an implementation and monitoring tool. ? This index could be useful for including urban trees in air quality mitigation plans. - A tree BVOC index is presented that calculates reduced BVOC emissions from planting lower-emitting urban tree species that has potential application for SIP compliance.

  9. Indexing books

    CERN Document Server

    Mulvany, Nancy C

    2009-01-01

    Since 1994, Nancy Mulvany's Indexing Books has been the gold standard for thousands of professional indexers, editors, and authors. This long-awaited second edition, expanded and completely updated, will be equally revered.Like its predecessor, this edition of Indexing Books offers comprehensive, reliable treatment of indexing principles and practices relevant to authors and indexers alike. In addition to practical advice, the book presents a big-picture perspective on the nature and purpose of indexes and their role in published works. New to this edition are discus

  10. Patient-specific kerma-area product as an exposure estimator in computed tomography: The concept and typical values

    International Nuclear Information System (INIS)

    The concept of the patient-specific kerma-area product (PSKAP) as an exposure estimator in computed tomography (CT) was suggested, but no detailed information on how to evaluate this quantity in practice was given. We extend the idea by proposing (i) a rigorous definition of PSKAP, and (ii) a method for its evaluation by a CT scanner. To demonstrate the performance of the method, we used the Siemens Somatom Open CT scanner to obtain PSKAP values (here denoted as PPSKA) for the standard CT dosimetry head phantom

  11. Scattering study at free air ionization chamber diaphragm; Estudo do espalhamento no diafragma da camara de ionizacao de ar livre

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Alexandre Lo Bianco dos

    2011-07-01

    The maim of this work consisted in the assessment of the correction factor for air kerma, due to scattered radiation in the diaphragm of the free-air ionization chamber model 481. LNMRl measurements were made to acquire x-ray spectra corresponding to the Qualities RQR-M, described in IEC 61627 standards (2005). These spectra were used as input data in the MC simulations. The operational range of energy spectra provide up to 35 keV. This energy range is typically used in diagnostic radiology, although there is not primary standard for air kerma. The determination of this factor is a fundamental process in the primary standardization of the air kerma. These factors were obtained by computer simulation using the Penelope code. The results are k{sub RQR-M1}=0,9946, k{sub RQR} {sub -M2}=0,9932, k{sub RQR-M3}=0,9978 and k{sub RQR-M4}=0,9885; with uncertainties of 0,007 and coverage factor equal to 2. lt can be concluded that, with respect to the diaphragm, the chamber can be used in the primary standard of air kerma. (author)

  12. Calibration methodology application of kerma area product meters in situ: Preliminary results

    International Nuclear Information System (INIS)

    The kerma-area product (KAP) is a useful quantity to establish the reference levels of conventional X-ray examinations. It can be obtained by measurements carried out with a KAP meter on a plane parallel transmission ionization chamber mounted on the X-ray system. A KAP meter can be calibrated in laboratory or in situ, where it is used. It is important to use one reference KAP meter in order to obtain reliable quantity of doses on the patient. The Patient Dose Calibrator (PDC) is a new equipment from Radcal that measures KAP. It was manufactured following the IEC 60580 recommendations, an international standard for KAP meters. This study had the aim to calibrate KAP meters using the PDC in situ. Previous studies and the quality control program of the PDC have shown that it has good function in characterization tests of dosimeters with ionization chamber and it also has low energy dependence. Three types of KAP meters were calibrated in four different diagnostic X-ray equipments. The voltages used in the two first calibrations were 50 kV, 70 kV, 100 kV and 120 kV. The other two used 50 kV, 70 kV and 90 kV. This was related to the equipments limitations. The field sizes used for the calibration were 10 cm, 20 cm and 30 cm. The calibrations were done in three different cities with the purpose to analyze the reproducibility of the PDC. The results gave the calibration coefficient for each KAP meter and showed that the PDC can be used as a reference instrument to calibrate clinical KAP meters. - Highlights: • The Patient Dose Calibrator (PDC) is a new equipment from Radcal that measures KAP. • This study aimed the calibration of KAP meters in situ using the PDC as a reference. • The method used for the calibration of the KAP meters was the tandem method. • This instrument calculates the dose that the patient receives during an X-ray examination. • The calibration procedure is important to correct the measurements performed with KAP meters

  13. DS02 fluence spectra for neutrons and gamma rays at Hiroshima and Nagasaki with fluence-to-kerma coefficients and transmission factors for sample measurements.

    Science.gov (United States)

    Egbert, Stephen D; Kerr, George D; Cullings, Harry M

    2007-11-01

    Fluence spectra at several ground distances in Hiroshima and Nagasaki are provided along with associated fluence-to-kerma coefficients from the Dosimetry System 2002 (DS02). Also included are transmission factors for calculating expected responses of in situ sample measurements of neutron activation products such as (32)P,(36)Cl,(39)Ar,(41)Ca, (60)Co,(63)Ni,(152)Eu, and (154)Eu. The free-in-air (FIA) fluences calculated in 2002 are available for 240 angles, 69 energy groups, 101 ground distances, 5 heights, 4 radiation source components, 2 cities. The DS02 code uses these fluences partitioned to a prompt and delayed portion, collapsed to 58 energy groups and restricted to 97 ground distances. This is because the fluence spectra were required to be in the same format that was used in the older Dosimetry System 1986 (DS86) computer code, of which the DS02 computer code is a modification. The 2002 calculation fluences and the collapsed DS02 code fluences are presented and briefly discussed. A report on DS02, which is available on the website at the Radiation Effects Research Foundation, provides tables and figures of the A-bomb neutron and gamma-ray output used as the sources in the 2002 radiation transport calculations. While figures illustrating the fluence spectra at several ground ranges are presented in the DS02 Report, it does not include any tables of the calculated fluence spectra in the DS02 report. This paper provides, at several standard distances from the hypocenter, the numerical information which is required to translate the FIA neutron fluences given in DS02 to a neutron activation measurement or neutron and gamma-ray soft-tissue dose. PMID:17643260

  14. Importance of the neutrons kerma coefficient in the planning of Brachytherapy treatments with Cf-252 sources; Importancia del coeficiente de kerma de neutrones en la planeacion de tratamientos de Braquiterapia con fuentes de Cf-252

    Energy Technology Data Exchange (ETDEWEB)

    Paredes G, L.; Balcazar G, M. [ININ, 52045 Ocoyocac, Estado de Mexico (Mexico); Azorin N, J. [Universidad Autonoma Metropolitana, 09000 Mexico D.F. (Mexico); Francois L, J.L. [UNAM, 04500 Mexico D.F. (Mexico)]. e-mail: lpg@nuclear.inin.mx

    2006-07-01

    The Cf-252 is a fast neutrons emitting radioisotope by spontaneous fission that can be used as sealed source in medicine applications, industry and research. Commercially its offer sources of different sizes, compact and with a fast neutrons emission of the order of 10{sup 6} n/s-{mu}g and an energy spectra that presents respectively maxim and average energy in 2.1 MeV and 0.7 MeV. In medicine new applications are being developed for the treatment of patient with hypoxic and voluminous tumors, where the therapy with photons has not given positive results, as well as for the protocols of therapy treatment by boron neutron capture, where very small sources of Cf-252 will be used with the interstitial brachytherapy technique of high and low dose rate. In this work an analysis of how the small differences that exist in the elementary composition of 4 wicked tumors, 4 ICRU healthy tissues and 3 substitute materials of ICRU tissue used in dosimetry are presented, its generate changes in the neutrons kerma coefficient in function of the energy and consequently in the absorbed dose in the interval of 11 eV to 29 MeV. These differences can produce maximum variations of the neutron kerma coefficients ratio for E{sub n} > 1 keV of the one: 15% tumor/ICRU guest healthy tissue, 12% ICRU tumor/muscle, 12% ICRU healthy tissues ICRU/ICRU muscle, 22% substitutes tissue/tumor and 22% ICRU substitutes tissue/muscle. Also, it was found that the average value of the neutrons kerma coefficient for the 4 wicked tumors is from 6% to 7% smaller that the average value for the soft tissue in the interval energy of interest for therapy with fast neutrons with E{sub n} > 1 MeV. These results have a special importance during the planning process of brachytherapy treatments with sources of {sup 252}Cf, to optimize and to individualize the patients treatments. (Author)

  15. Cavity's theory of Bragg-Gray applied to ionization free-air chamber

    International Nuclear Information System (INIS)

    Ionization's chambers are kinds of dosimeters more useful to measurements such as required in radiotherapy. Are detectors of non pulse type (mean effect) and gaseous, calibrate in Kerma, unit Gray (Gy).The objective of this work is to relate the physical theory existing and the construction shape of the primary standard, that is the ionization of free-air chamber with variable volume, manufactured by Victoreen Instruments, used to measure magnitude air Kerma performed by the 'Laboratorio Nacional de Metrologia das Radiacoes Ionizantes' from Instituto de Radioprotecao e Dosimetria - LNMRI-IRD. For in such a way, will be done an evaluation of the chamber capability, and the sensibility of radiations of low energy, range from 20 kV to 80 kV, in the qualities of mammography not attenuate, mammography attenuate, diagnostic, therapy e protection through the construction's acquaintance, dimensions of pieces components and operational tests. Concerning the chamber's construction, the mechanical set consists of two cylinders of aluminium concentrically that moves axially between itself, objectifying the variation of internal volume (variable volume). The practical application of the Bragg-Gray cavity's theory can be applied to the chamber, where the reasons of the absorbed dose in different means to the same fluency is equal to the reason of stopping powers of two means. >From the definition of Kerma we can obtain the adsorbed dose and existing particles in (CPE), the absorbed dose is equal to the Kerma's collision. (author)

  16. AP Index

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Planetary Amplitude index - Bartels 1951. The a-index ranges from 0 to 400 and represents a K-value converted to a linear scale in gammas (nanoTeslas)--a scale that...

  17. Evaluation of skin entry kerma in radiological examinations at the Hospital de Clinicas, Parana, Brazil; Avaliacao de kerma de entrada na pele em exames radiologicos no Hospital de Clinicas do Parana, Brasil

    Energy Technology Data Exchange (ETDEWEB)

    Porto, Lorena E.; Schelin, Hugo R.; Santos, Amanda C. dos; Bunick, Ana Paula; Paschuk, Sergei; Denyak, Valeriy [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil); Tilly Junior, Joao G. [Universidade Federal do Parana (UFPR), Curitiba, PR (Brazil). Hospital de Clinicas; Khoury, Helen J., E-mail: khoury@ufpe.b [Universidade Federal de Pernambuco (UFPE/DEN), Recife, PE (Brazil). Dept. de Energia Nuclear

    2011-10-26

    This paper evaluates the skin entry dose of pediatric and adults patients when submitted to radiological examinations at the Hospital de Clinicas do Parana, Brazil, as part integrate of the data assessment of International Atomic Energy Agency (IAEA) for Latin America. It was performed measurements of dose for evaluation of skin entry kerma in pediatric patients in thorax AP/PA examinations, adults of thorax in AP/PA, cranio caudal mammography and median lateral and patients of computerized tomography in examination of head, thorax and abdomen. The obtained data demonstrate the necessity of verification of diagnostic analysis standards. The great value amplitudes demonstrate the incompatibility of examination executions with those recommended by the literature. The dose values presented partially inside the range recommended and the other over the expected for the due examination when compared with the literature

  18. Air temperature thresholds to evaluate snow melting at the surface of Alpine glaciers by T-index models: the case study of Forni Glacier (Italy)

    OpenAIRE

    A. Senese; Maugeri, M.; E. Vuillermoz; Smiraglia, C.; G. Diolaiuti

    2014-01-01

    The glacier melt conditions (i.e.: null surface temperature and positive energy budget) can be assessed by analyzing meteorological and energy data acquired by a supraglacial Automatic Weather Station (AWS). In the case this latter is not present the assessment of actual melting conditions and the evaluation of the melt amount is difficult and simple methods based on T-index (or degree days) models are generally applied. These models require the choice of a correct temperatu...

  19. Determination of mass attenuation coefficients, effective atomic numbers, effective electron numbers and kermas for Earth and Martian soils

    International Nuclear Information System (INIS)

    Highlights: ? The present work have been expected to be lead to extraterrestrial research. ? Our work have thrown light on the radiation physics and the applications. ? The data which are used to shielding application are not available in the literature. - Abstract: Total mass attenuation coefficients, effective atomic numbers, effective electron numbers and kerma values for Earth and Martian soils are calculated in the energy range from 1 keV to 100 GeV. The values of mass attenuation and absorption coefficients used in calculations are taken from the WinXCOM program and correct data base. Contributions of different scatterings on the total mass attenuation coefficients of the soils are presented. In addition, the obtained results for Martian soils are compared with the results for Earth soils. The similarities of Earth and Martian soils are also investigated.

  20. Detection and estimation trends linked to air quality and mortality on French Riviera over the 1990-2005 period to develop a prediction model of an aggregate risk index

    Science.gov (United States)

    Sicard, P.; Mangin, A.; Hebel, P.; Lesne, O.; Malléa, P.

    2009-04-01

    There is a profound relation between human health and well being from the one side and air pollution levels from the other. Air quality in South of France and more specifically in Nice, is known to be bad, especially in summer. The main objectives are to establish correlations between air pollution, exposure of people and reactivity of these people to this aggression, to validate a risk index built from air quality and pollen data in the area of Nice and to construct a prediction model of this sanitary index. The spatial extent of the experiment will be mainly the territory of "Alpes Maritimes". All the tasks are performed in collaboration with the "Heath-Environment Network" of the "Centre Hospitalier Universitaire" of Nice. The development of an adequate tool for observation (health index and/or indices per pathology) to understand impacts of pollution levels in an area is of utmost importance. These indexes should take into account the possible adverse effects associated with the coexistence of all the pollutants and environmental parameters. This tool must be able to inform the citizens about the levels of pollution in an adequate and understandable way but also to be used by relevant authorities to take a series of predetermined measures to protect the health of the population. This paper describes the first step to construct a prediction model of this sanitary index with a confidence interval 99% (and 95%): detection and estimation trends observed in concentrations of pollutants, emissions and mortality over the 1990-2005 period in the "Alpes Maritimes" area. The non-parametric Mann-Kendall test has been developed for detecting and estimating monotonic trends in the time series and applied in our study at annual values of pollutants air concentrations. An important objective of many environmental monitoring programs is to detect changes or trends in pollution levels over time. Over the period 1990-2005, concerning the emissions of the main pollutants, we obtained significant decreasing trends. Between 1994 and 2005, from the SO2 concentrations, decreasing trends of 1.2 %.year-1 (urban stations) and of 5.4 %.year-1 (traffic stations) were calculated. Over the same period, we obtained a decreasing trend of 1.3 %.year-1 for the NO2 concentrations (urban stations) and of 3.1 %.year-1 for the traffic stations. In addition, a decreasing trend of 0.5 %.year-1 was calculated for the suburban stations over the 1998-2005 period. Globally, the concentration of the major pollutants showed a clear downward trend and those main reductions have reflected the reduction policy of the emissions over twenty years. By considering the ozone mean values in urban areas over the 1997-2005 period, an increasing of 3.0 %.year-1 was obtained with annual averages and 3.9 %.year-1 with median values. Over the 1990-2005 period, we obtained significant decreasing trends concerning the "ischemic heart diseases" (- 1.20 %.year-1) and "asthma" (- 4.03 %.year-1) categories. No significant sex-related difference was identified for these groups. An annual change rate of + 0.31 %.year-1 for the "airway diseases" and of + 2.50%.year-1 for the "unknown causes" were identified. For these categories, we noted a sex-related difference. In fact, we obtained for males a decreasing trend contrary to females.

  1. Intelligent indexing

    International Nuclear Information System (INIS)

    In this paper we discuss the relevance of artificial intelligence to the automatic indexing of natural language text. We describe the use of domain-specific semantically-based thesauruses and address the problem of creating adequate knowledge bases for intelligent indexing systems. We also discuss the relevance of the Hilbert space ι2 to the compact representation of documents and to the definition of the similarity of natural language texts. (author). 17 refs., 2 figs

  2. Louisiana ESI: INDEX (Index Polygons)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains vector polygons representing the boundaries of all the hardcopy cartographic products produced as part of the Environmental Sensitivity Index...

  3. Characterization of a free-air ionization chamber in direct X-ray beams as used in mammography

    International Nuclear Information System (INIS)

    At this work stability and characterization tests were undertaken on a Victoreen free-air ionization chamber, model 481. The tests were realized using direct X-ray beams as a contribution for its establishment as a primary standard system of the quantity air kerma. The characterization tests were: saturation curve, ion collection efficiency, polarity effect, response linearity with the air kerma rate and response linearity with the chamber volume variation. The ion collection efficiency allowed the determination of the ion recombination factor. Most of the test results showed agreement with the limits established by international standards. Furthermore, the air attenuation factors for the mammography beams with aluminum and molybdenum filters were obtained. The factors for photon transmission and scattering at the diaphragm edges were also determined for mammography beams with aluminum filter and for the standard beam with molybdenum filter. (author)

  4. GCUBE Indexing

    Directory of Open Access Journals (Sweden)

    M.Laxmaiah

    2013-07-01

    Full Text Available Spatial Online Analytical Processing System involves the non-categorical attribute information alsowhereas standard online analytical processing system deals with only categorical attributes. Providingspatial information to the data warehouse (DW; twomajor challenges faced are; 1.Defining andAggregation of Spatial or Continues values and 2.Representation, indexing, updating and efficient queryprocessing. In this paper, we present GCUBE (Geographical Cube storage and indexing procedure toaggregate the spatial information/Continuous values. We employed the proposed approach storing andindexing using synthetic and real data sets and evaluated its build, update and Query time. It is observedthat the proposed procedure offers significant performance advantage.

  5. Indexing mechanisms

    International Nuclear Information System (INIS)

    It is stated that the indexing mechanism described can be used in a nuclear reactor fuel element inspection rig. It comprises a tubular body adapted to house a canister containing a number of fuel elements located longtitudinally, and has two chucks spaced apart for displacing the fuel elements longitudinally in a stepwise manner, together with a plunger mechanism for displacing them successively into the chucks. A measuring unit is located between the chucks for measuring the diameter of the fuel elements at intervals about their circumferences, and a secondary indexing mechanism is provided for rotating the measuring unit in a stepwise manner. (U.K.)

  6. Doses monitoring in radiology: calibration of air kerma-area product (P{sub KA}) meters; Monitoracao de doses em radiologia: a calibracao de medidores do produto kerma-area (P{sub KA})

    Energy Technology Data Exchange (ETDEWEB)

    Terini, Ricardo Andrade; Campelo, Maria Carolina de Santana; Almeida Junior, Jose Neres de, E-mail: rterini@pucsp.br [Pontificia Universidade Catolica de Sao Paulo (PUC-SP), SP (Brazil); Herdade, Silvio Bruni; Pereira, Marco Aurelio Guedes [Universidade de Sao Paulo (IEE/USP), SP (Brazil). Instituto de Energia e Ambiente

    2013-11-15

    Materials and methods: different qualities of both incident and transmitted beams were utilized in conditions similar to a clinical setting, analyzing the influence from the reference dosimeter, from the distance between meters, from the filtration and from the average beam energy. Calibrations were performed directly against a standard 30 cm{sup 3} cylindrical chamber or a parallel-plate monitor chamber, and indirectly against the PDC meter. Results: the lowest energy dependence was observed for transmitted beams. The cross calibration between the Diamentor E2 and the PDC meters, and the PDC presented the greatest propagation of uncertainties. Conclusion: the calibration coefficient of the PDC meter showed to be more stable with voltage, while the Diamentor E2 calibration coefficient was more variable. On the other hand, the PDC meter presented greater uncertainty in readings (5.0%) than with the use of the monitor chamber (3.5%) as a reference. (author)

  7. Effect of indoor air pollution during cooking on peak expiratory flow rate and its association with exposure index in rural women.

    Science.gov (United States)

    Sukhsohale, Neelam D; Narlawar, Uday W; Phatak, Mrunal S; Agrawal, Sanjay B; Ughade, Suresh N

    2013-01-01

    Routine exposure to domestic cooking fuels is an important source of indoor air pollution causing deterioration of lung function. We conducted a community based cross-sectional study in 760 non-smoking rural women involved in household cooking with four types of cooking fuels i.e. Biomass, Kerosene stove, Liquid Petroleum Gas (LPG) and Mixed (combination of two and more cooking fuels). Peak Expiratory Flow Rate (PEFR) less than 80% of the predicted was considered as abnormal PEFR. The overall prevalence of abnormal PEFR was found to be 29.1% with greater predominance among biomass fuel users (43.3%) with high risk ratio (1.86) as compared to kerosene (0.63), LPG (0.75) and mixed (0.66) fuel users. However the pair wise comparison of different groups of cooking fuels by Marascuilo procedure reported significant differences within different groups except kerosene--mixed group. The study also demonstrated a negative correlation between observed PEFR and exposure indices in different cooking fuels (r = -0.51). Our results indicate that prolonged exposure to cooking fuels particularly biomass fuels as a source of cooking adversely affects PEFR in nonsmoking rural women. PMID:24617169

  8. Evaluated cross section libraries and kerma factors for neutrons up to 100 MeV on 40Ca and 31P

    International Nuclear Information System (INIS)

    The authors present evaluations of the interaction of 20 to 100 MeV neutrons with calcium and phosphorus, which follows on from the previous work on carbon, nitrogen, and oxygen. The aim is to accurately represent integrated cross sections, inclusive emission spectra, and kerma factors, in a data library which can be used in radiation transport calculations. They apply the GNASH nuclear model code, which includes Hauser-Feshbach, preequilibrium, and direct reaction mechanisms, and use experimental measurements to optimize the calculations. Total, elastic, and nonelastic cross sections, angle-energy correlated emission spectra for light ejectiles with A ? 4 and gamma-rays, and average energy depositions, are determined. The expected accuracy of the calculated cross sections and kerma factors is discussed

  9. Evaluated cross section libraries and kerma factors for neutrons up to 100 MeV on 16O and 14N

    International Nuclear Information System (INIS)

    We present evaluations of the interaction of 20 to 100 MeV neutrons with oxygen and nitrogen nuclei, which follows on from our previous work on carbon. Our aim is to accurately represent integrated cross sections, inclusive emission spectra, and kerma factors, in a data library which can be used in radiation transport calculations. We apply the FKK-GNASH nuclear model code, which includes Hauser-Feshbach, preequilibrium, and direct reaction mechanisms, and use experimental measurements to optimize the calculations. We determine total, elastic, and nonelastic cross sections, angle-energy correlated emission spectra, for light ejectiles with A?4 and gamma-rays, and average energy depositions. Our results for charged-particle emission spectra agree well with the measurements of Subramanian et al.. We compare kerma factors derived from our evaluated cross sections with experimental data, providing an integral benchmarking of our work. The evaluated data libraries are available as electronic files

  10. Calculation and evaluation of cross-sections and kerma factors for neutrons up to 100 MeV on {sup 16}O and {sup 14}N

    Energy Technology Data Exchange (ETDEWEB)

    Chadwick, M.B. [California Univ., Livermor, CA (United States). Lawrence Livermore National Lab.; Young, P.G.

    1997-03-01

    We present evaluations of the interaction of neutrons with energies between 20 and 100 MeV with oxygen and nitrogen nuclei, which follows on from our previous work on carbon. Our aim is to accurately represent integrated cross sections, inclusive emission spectra, and kerma factors, in a data library which can be used in radiation transport calculations. We apply the FKK-GNASH nuclear model code, which includes Hauser-Feshbach, preequilibrium, and direct reaction mechanisms, and use experimental measurements to optimize the calculations. We determine total, elastic, and nonelastic cross sections, angle-energy correlated emission spectra for light ejectiles with A {<=} 4 and gamma-rays, and average energy depositions. Our results for charged-particle emission spectra agree well with the measurements of Subramanian et al. We compare kerma factors derived from our evaluated cross sections with experimental data, providing an integral benchmarking of our work. (author). 52 refs.

  11. Application of low cost GaAs LED as neutron kerma dosimeter and fluence monitor at FLASH

    International Nuclear Information System (INIS)

    Displacement damage caused by fast neutrons in unbiased Gallium Arsenide (GaAs) Light Emitting Diodes (LED) resulted in a reduction of the light output. On the other hand, a similar type of LED irradiated with gamma rays from a 60Co source up to a dose level in excess of 1.0 kGy (1.0 x 105 rad) was found to show no significant drop of the light emission. This phenomenon was used to develop a low cost passive fluence monitor and kerma dosemeter for accelerator-produced neutrons. These LED-dosemeters were used to assess the integrated fluence of photoneutrons, which were contaminated with a strong bremsstrahlung gamma-background generated by the 730 MeV superconducting electron linac of the FLASH (Free Electron Laser at Hamburg) at Deutsches Elektronen-Synchrotron (DESY). The applications of GaAs LED as a routine neutron fluence monitor and displacement damage precursor for the electronic components located in high-energy accelerator environment are highlighted. (orig.)

  12. Variacion temporal de índices de precipitaciones extremas en el centro de la provincia de Buenos Aires / Temporal variation of extreme precipitations indexes in the centre of Buenos Aires province

    Scientific Electronic Library Online (English)

    Mónica, Gelmi; Rafael, Seoane.

    2013-06-01

    Full Text Available El objetivo de esta investigación consiste en estudiar la evolución temporal de precipitaciones diarias para detectar la presencia de tendencias y la frecuencia de eventos extremos. Las series de precipitaciones observadas corresponden a cuatro estaciones meteorológicas ubicadas en el centro de la P [...] rovincia de Buenos Aires, Argentina. Los cambios en las precipitaciones extremas a nivel diario se evalúan con los índices propuestos por la World Meteorological Organization-Commission for Climatology (WMO-CCL) y el World Climate Research Programme (WCRP) - Climate Variability and Predictability. Para estudiar los posibles cambios en la relación período de retorno - precipitaciones máximas se aplicaron a las series dos funciones de densidad de probabilidades, la Generalizada de Valores Extremos y la Gamma de dos parámetros. Los resultados estimados con las dos funciones de densidad de probabilidades de la precipitación máxima, generalmente muestran un incremento de la precipitación asociado a la misma probabilidad de ocurrencia en el período 1971-1999 respecto a 1951-1970. Los eventos de precipitación que produjeron crecidas, ocurridos en Olavarría y Azul desde la década del 80 son una clara indicación del interés del estudio de este tema tanto por sus implicancias sociales asociadas con las inundaciones, como por la necesidad de actualizar las estimaciones de los parámetros de diseño de obras hidráulicas. Los valores de los índices estimados indican la existencia de una tendencia positiva en la precipitación en la mayoría de las estaciones meteorológicas y una mayor frecuencia de ocurrencia de valores extremos para el periodo 1971-1999 en relación al periodo 1951-1970. Abstract in english The objective of this research is to study the temporal evolution of daily precipitation in order to detect the presence of trends and to estimate the frequency of extreme events. The observed precipitation series correspond to four meteorological stations located in the center of the Province of Bu [...] enos Aires, Argentina. Changes in daily extreme precipitation were assessed through the indices proposed by the World Meteorological Organization-Commission for Climatology (WMO-CCL) and the World Climate Research Program (WCRP) -Climate Variability and Predictability. In order to analyze possible changes in the return period - maximum precipitation relationship, two probability density functions were applied to the series, the Generalized Extreme Values and the two parameters Gamma. The obtained results show, in general, a higher probability of occurrence of greater precipitations over the period 1971-1999 respect of period 1951-1970. The rainfall events that caused floods in Olavarría and Azul since the '80s clearly show the interest of studying this subject, not only because of its social implications associated to floods, but the demand of developing techniques to update the estimation of design parameters of hydraulic works. The estimated indices suggest a positive trend in the precipitation at most of the analyzed meteorological stations and a higher frequency of occurrence of extreme values over the period 1971-1999 compared to the period 1951-1970.

  13. Evaluated cross-section libraries and kerma factors for neutrons up to 100 MeV on 12C

    International Nuclear Information System (INIS)

    A program is being carried out at Lawrence Livermore National Laboratory to develop high-energy evaluated nuclear data libraries for use in Monte Carlo simulations of cancer radiation therapy. In this report we describe evaluated cross sections and kerma factors for neutrons with incident energies up to 100 MeV on 12C. The aim of this effort is to incorporate advanced nuclear physics modeling methods, with new experimental measurements, to generate cross section libraries needed for an accurate simulation of dose deposition in fast neutron therapy. The evaluated libraries are based mainly on nuclear model calculations, benchmarked to experimental measurements where they exist. We use the GNASH code system, which includes Hauser-Feshbach, preequilibrium, and direct reaction mechanisms. The libraries tabulate elastic and nonelastic cross sections, angle-energy correlated production spectra for light ejectiles with A?and kinetic energies given to light ejectiles and heavy recoil fragments. The major steps involved in this effort are: (1) development and validation of nuclear models for incident energies up to 100 MeV; (2) collation of experimental measurements, including new results from Louvain-la-Nueve and Los Alamos; (3) extension of the Livermore ENDL formats for representing high-energy data; (4) calculation and evaluation of nuclear data; and (5) validation of the libraries. We describe the evaluations in detail, with particular emphasis on our new high-energy modeling developments. Our evaluations agree well with experimental measurements of integrated and differential cross sections. We compare our results with the recent ENDF/B-VI evaluation which extends up to 32 MeV

  14. Spatial variability of air dry bulb temperature and black globe humidity index in a broiler house during the heating phase / Variabilidade espacial de variáveis ambientais em um galpão avícola durante a fase de aquecimento

    Scientific Electronic Library Online (English)

    Patrícia F., Ponciano; Tadayuki, Yanagi Junior; Gabriel A. E S., Ferraz; João D., Scalon; Leonardo, Schiassi.

    2013-06-01

    Full Text Available A temperatura de bulbo seco do ar (t bs) bem como o índice de temperatura do globo negro e umidade (ITGU) exercem grande influência no desenvolvimento de frangos de corte durante a fase de aquecimento. Sendo assim, o objetivo deste trabalho foi analisar a estrutura e a magnitude da variabilidade esp [...] acial da t bs e ITGU, utilizando ferramentas da geoestatística por meio de análise de semivariograma e, ainda, a produção de mapas de isolinhas por meio de interpolação por krigagem. O experimento foi conduzido na mesorregião oeste de Minas Gerais, na primavera de 2010, em um galpão comercial com sistema de aquecimento constituído de duas fornalhas de aquecimento indireto do ar, durante os primeiros 14 dias de vida das aves. Os dados foram registrados em intervalos de cinco minutos, no período das 8 às 10 horas. As variáveis foram avaliadas por semivariograma ajustado pelo método da máxima verossimilhança restrita (REML), testando-se os modelos esférico e exponencial. Os mapas de krigagem foram produzidos baseados no melhor método de ajuste do semivariograma. As técnicas da geoestatística possibilitaram caracterizar a variabilidade da t bs e ITGU, permitindo a observação da dependência espacial. Além disso, com a utilização da geoestatística e dos mapas de distribuição, pode-se identificar falhas no sistema de aquecimento, em regiões do galpão que poderiam vir a prejudicar o desenvolvimento dos pintinhos. Abstract in english The air dry-bulb temperature (t db),as well as the black globe humidity index (BGHI), exert great influence on the development of broiler chickens during their heating phase. Therefore, the aim of this study was to analyze the structure and the magnitude of the t db and BGHI spatial variability, usi [...] ng geostatistics tools such as semivariogram analysis and also producing kriging maps. The experiment was conducted in the west mesoregion of the states of Minas Gerais in 2010, in a commercial broiler house with heating system consisting of two furnaces that heat the air indirectly, in the firsts 14 days of the birds' life. The data were registered at intervals of five minutes in the period from 8 a.m. to 10 a.m. The variables were evaluated by variograms fitted by residual maximum likelihood (REML) testing the Spherical and Exponential models. Kriging maps were generated based on the best model used to fit the variogram. It was possible to characterize the variability of the t db and BGHI, which allowed observing the spatial dependence by using geostatistics techniques. In addition, the use of geostatistics and distribution maps made possible to identify problems in the heating system in regions inside the broiler house that may harm the development of chicks.

  15. Estimation of entrance dose on chest radiographs according to the exposure index on Computerized Radiology System: preliminary results

    International Nuclear Information System (INIS)

    Digital radiology has improved image quality in radiographs in comparison to screen/film systems though the visual control of the quantity of radiation involved on these exams became more demanding due to the low perception of over and underexposed images. Therefore, this study aims to analyze the exposure index (EI) from chest examinations and relate them to the entrance skin dose. Indices from 29 patients and kerma entrance dose were correlated. A correlation coefficient equal to 0,6881 was calculated. EI and entrance dose are correlated positive and moderately, indicating the relevance to deepen the subject. (author)

  16. Characterization of a free-air ionization chamber in direct X-ray beams as used in mammography; Caracterizacao de uma camara de ionizacao de ar-livre em feixes diretos de raios X utilizados em mamografia

    Energy Technology Data Exchange (ETDEWEB)

    Lima, Mateus Hilario de

    2014-08-01

    At this work stability and characterization tests were undertaken on a Victoreen free-air ionization chamber, model 481. The tests were realized using direct X-ray beams as a contribution for its establishment as a primary standard system of the quantity air kerma. The characterization tests were: saturation curve, ion collection efficiency, polarity effect, response linearity with the air kerma rate and response linearity with the chamber volume variation. The ion collection efficiency allowed the determination of the ion recombination factor. Most of the test results showed agreement with the limits established by international standards. Furthermore, the air attenuation factors for the mammography beams with aluminum and molybdenum filters were obtained. The factors for photon transmission and scattering at the diaphragm edges were also determined for mammography beams with aluminum filter and for the standard beam with molybdenum filter. (author)

  17. Evaluation of cross sections and calculation of kerma factors for neutrons up to 80 MeV on {sup 12}C

    Energy Technology Data Exchange (ETDEWEB)

    Harada, M.; Watanabe, Y. [Kyushu Univ., Fukuoka (Japan); Chiba, S.; Fukahori, T.

    1997-03-01

    We have evaluated the cross sections for neutrons with incident energies from 20 to 80 MeV on {sup 12}C for the JENDL high-energy file. The total cross sections were determined by a generalized least-squares method with available experimental data. The cross sections of elastic and inelastic scattering to the first 2{sup +} were evaluated with the theoretical calculations. The optical potentials necessary for these calculations were derived using a microscopic approach by Jeukenne-Lejeune-Mahaux. For the evaluation of double differential emission cross sections (DDXs), we have developed a code system SCINFUL/DDX in which total 35 reactions including the 3-body simultaneous breakup process (n+{sup 12}C {yields} n+{alpha}+{sup 8}Be) can be taken into consideration in terms of a Monte Carlo method, and have calculated the DDXs of all light-emissions (A{<=}4) and heavier reaction products. The results for protons, deuterons, and alphas showed overall good agreement with experimental data. The code is also applicable for calculations of total and partial kerma factors. Total kerma factors calculated for energies from 20 to 80 MeV were compared with the measurements and the other latest evaluations from the viewpoints of medical application and nuclear heating estimation. (author)

  18. Photon and neutron fluence-to-kerma conversion factors for ICRP-1975 reference man using improved elemental compositions for bone and marrow of the skeleton

    International Nuclear Information System (INIS)

    A twelve-element approximation of the total-body, soft-tissue and skeletal components of ICRP-1975 Reference Man is used to investigate particle fluence-to-kerma conversion factors for photons with energies between 1 keV and 20 MeV and neutrons with energies between 0.0253 eV and 20 MeV. Several recent ICRP revisions to the elemental composition of Reference Man, which have not been included in other kerma-factor calculations, are taken into account. This work suggests some additional revisions to the major-element content (i.e., H, C, N, and O) and to the mineral and trace-element content (i.e., Na, Mg, P, S, Cl, K, Ca, and Fe) of various total-body, soft-tissue, and skeletal components of Reference Man. The revisions to the bone and red marrow of the skeleton offer significant new refinements in red-bone-marrow dosimetry

  19. Human occupations and environmental changes in the Nile valley during the Holocene: The case of Kerma in Upper Nubia (northern Sudan)

    Science.gov (United States)

    Honegger, Matthieu; Williams, Martin

    2015-12-01

    Our article presents a detailed Holocene archaeological sequence from the Nile Valley at Kerma in Upper Nubia, northern Sudan. This sequence retraces the evolution of human populations thanks to the study of several sites, supported by 90 14C dates. Reconstruction of the environmental changes was supported by a study of dated stratigraphic sections located near the archaeological sites studied, and illustrates the effects on human occupation of changes in river flow and floods, which are in turn forced by climatic changes. The results shed new light on the evolutionary dynamics of the Holocene populations in Nile Valley, little known due to the numerous hiatuses in occupation. When compared with the situation in the Sahara and the rest of the Nile Valley, they confirm that the initial occupation took place ca. 10.5 kyr BP after the start of the African Humid Period, followed by a migration towards the banks of the Nile commencing 7.3 kyr BP. They also confirm the appearance of the Neolithic by ca. 8.0 kyr BP. The Kerma stratigraphic sequences show two prosperous periods (10-8 and 7-6 kyr BP) and two hiatuses in the occupation of the sites (7.5-7.1 and 6.0-5.4 kyr BP), resulting from increased aridity.

  20. Preliminary results on characterization tests of a free-air chamber

    Energy Technology Data Exchange (ETDEWEB)

    Lima, Mateus H. de; Caldas, Linda V.E., E-mail: mhlima@ipen.br, E-mail: lcaldas@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2013-07-01

    Free-air chambers are widely used in radiation metrology laboratories as primary standards for air kerma in the range of low and medium x-ray energies. There are two types of free-air ionization chambers: the parallel-plate type and the cylindrical type. The first one is used as primary standard at laboratories as the NIST, BIPM and NPL. The cylindrical type, on the other hand, is used in the standard calibration laboratories of Germany, Italy and Taiwan. In 1961, Attix proposed a design of a cylindrical free-air ionization chamber with a variable length presenting some advantages over the fixed-length design. The Instituto de Pesquisas Energeticas e Nucleares (IPEN) has a Victoreen chamber, model 481, based on this design for x-ray energies up 50 keV. The objective of this study is to investigate the possibility of using this chamber as a primary standard of air kerma in the Calibration Laboratory of IPEN. In this work are presented the preliminary results of the characterization tests of the free-air ionization chamber: leakage current, stability of response, saturation curve, collection efficiency, response linearity and response linearity with the cylinder displacement. (author)

  1. Estimating the Mean Annual Surface Air Temperature at Armagh Observatory, Northern Ireland, and the Global Land-Ocean Temperature Index for Sunspot Cycle 24, the Current Ongoing Sunspot Cycle

    Science.gov (United States)

    Wilson, Robert M.

    2013-01-01

    As noted by Gray et al., Sir William Herschel was the first to suggest a possible close connection between the Sun and the Earth’s climate. The Sun, being the source of energy that impacts and drives the Earth’s climate system, displays a variety of changes over both short and long term time scales, the most obvious examples being the somewhat regular waxing and waning of sunspots with time (i.e., the sunspot cycle (SC)), first described by Samuel Heinrich Schwabe, a German apothecary and amateur astronomer who observed the Sun from Dessau, Germany, and the now well established variation of the Sun’s irradiance over the SC. Other factors related to the SC have been linked to changes in climate as well. Some of these other factors include the role of cosmic rays and the solar wind (i.e., the geomagnetic cycle) on climate, as well as the apparent close association between trends in global and northern hemispheric temperature and the length of the SC, although some investigators have described the inferred association between climate and, in particular, SC length as now being weak. More recently, Solheim et al. have reported on the relation between SC length and the average temperature in the same and immediately following SC for a number of meteorological stations in Norway and in the North Atlantic region. They noted that while they found no significant trend (correlation) between SC length and the average temperature when measured for the same cycle, in contrast, they found a significant negative trend when SC length was compared with the following cycle’s average temperature. From this observation, they suggested that average northern hemispheric temperature during the present ongoing SC (SC24) will be lower by about 0.9 °C than was seen in SC23 (spanning 1996–2007, based on yearly averages of sunspot number (SSN), and onset for SC24 occurring in 2008). The purpose of this Technical Publication (TP) is to examine the annual variations of the Armagh surface air temperature (ASAT) and the Global Land-Ocean Temperature Index (GLOTI) in relation to SSN and the SC in order to determine their likely values during SC24. Hence, it may provide insight as to whether solar forcing of global temperature is now lessening as a contributor to global warming, thereby indicating a possible cooling in the near term immediate future that potentially could ameliorate the effect of increased anthropogenic warming.

  2. EJSCREEN Indexes 2015 Public

    Data.gov (United States)

    U.S. Environmental Protection Agency — There is an EJ Index for each environmental indicator. There are eight EJ Indexes in EJSCREEN reflecting the 8 environmental indicators. The EJ Index names are:...

  3. EJSCREEN Indexes 2015 Internal

    Data.gov (United States)

    U.S. Environmental Protection Agency — There is an EJ Index for each environmental indicator. There are 12 EJ Indexes in EJSCREEN reflecting the 12 environmental indicators. The EJ Index names are:...

  4. Are exposure index values consistent in clinical practice? A multi-manufacturer investigation

    International Nuclear Information System (INIS)

    The advent of digital radiography poses the risk of unnoticed increases in patient dose. Manufacturers have responded to this by offering an exposure index (EI) value to the clinician. Whilst the EI value is a measure of the air kerma at the detector surface, it has been recommended by international agencies as a method of monitoring radiation dose to the patient. Recent studies by the group have shown that EI values are being used in clinical practice to monitor radiation dose and assess image quality. This study aims to compare the clinical consistency of the EI value in computed radiography (CR) and direct digital radiography (DR) systems. An anthropomorphic phantom was used to simulate four common radiographic examinations: skull, pelvis, chest and hand. These examinations were chosen as they provide contrasting exposure parameters, image detail and radiation dose measurements. Four manufacturers were used for comparison: Agfa Gaevert CR, Carestream CR, Philips Digital Diagnost DR and Siemens DR. For each examination, the phantom was placed in the optimal position and exposure parameters were chosen in accordance with European guidelines and clinical practice. Multiple exposures were taken and the EI recorded. All exposure parameters and clinical conditions remained constant throughout. For both DR systems, the EI values remained consistent throughout. No significant change was noted in any examination. In both CR systems, there were noteworthy fluctuations in the EI values for all examinations. The largest for the Agfa system was a variation of 1.88-2.21 for the skull examination. This represents to the clinician a doubling of detector dose, despite all exposure parameters remaining constant. In the Kodak system, the largest fluctuation was seen for the chest examination where the EI ranged from 2560 to 2660, representing approximately an increase of 30% in radiation dose, despite consistent parameters. The fluctuations seen with the CR systems are most likely due to image processing delay, replacing of the imaging plate and calibration factors. Fluctuations in EI values may result in confusion to the clinician and unnecessary repeat examinations. The reliability of EI values as a feedback mechanism for CR is also questionable. (authors)

  5. Why Indexing Works

    OpenAIRE

    Heaton, J. B.; Polson, N. G.; de Witte, J. H.

    2015-01-01

    We develop a simple stock selection model to explain why active equity managers tend to underperform a benchmark index. We motivate our model with the empirical observation that the best performing stocks in a broad market index perform much better than the other stocks in the index. While randomly selecting a subset of securities from the index increases the chance of outperforming the index, it also increases the chance of underperforming the index, with the frequency of underperformance be...

  6. A comparison of in-air and in-water calibration of a dosimetry system used for radiation dose assessment in cancer therapy

    OpenAIRE

    Arshed Waheed; Mahmood Khalid; Qazi Ikramullah; Ullah Asad; Akhter Perveen; Ahmad Salman Syed; Jamil Zeeshan

    2010-01-01

    An accurate calibration of the therapy level radiation dosimetry system has a pivotal role in the accuracy of dose delivery to cancer patients. The two methods used for obtaining a tissue equivalent calibration of the system: air kerma calibration and its conversion to a tissue equivalent value (absorbed dose to water) and direct calibration of the system in a water phantom, have been compared for identical irradiation geometry. It was found that the deviation between the two methods remained...

  7. Lobby index in networks

    CERN Document Server

    Korn, A; Telcs, A

    2008-01-01

    We propose a new node centrality measure in networks, the lobby index, which is inspired by Hirsch's h-index. It is shown that in scale free networks the l-index has power tail with exponent square of the exponent of the degree distribution one. Properties of the l-index and extensions are discussed.

  8. Conception and realization of a parallel-plate free-air ionization chamber for the absolute dosimetry of an ultrasoft X-ray beam

    International Nuclear Information System (INIS)

    We report the design of a millimeter-sized parallel plate free-air ionization chamber (IC) aimed at determining the absolute air kerma rate of an ultra-soft X-ray beam (E = 1.5 keV). The size of the IC was determined so that the measurement volume satisfies the condition of charged-particle equilibrium. The correction factors necessary to properly measure the absolute kerma using the IC have been established. Particular attention was given to the determination of the effective mean energy for the 1.5 keV photons using the PENELOPE code. Other correction factors were determined by means of computer simulation (COMSOL™and FLUKA). Measurements of air kerma rates under specific operating parameters of the lab-bench X-ray source have been performed at various distances from that source and compared to Monte Carlo calculations. We show that the developed ionization chamber makes it possible to determine accurate photon fluence rates in routine work and will constitute substantial time-savings for future radiobiological experiments based on the use of ultra-soft X-rays

  9. Conception and realization of a parallel-plate free-air ionization chamber for the absolute dosimetry of an ultrasoft X-ray beam

    Energy Technology Data Exchange (ETDEWEB)

    Groetz, J.-E., E-mail: jegroetz@univ-fcomte.fr; Mavon, C.; Fromm, M. [Laboratoire Chrono-Environnement, UMR CNRS 6249, Université de Franche-Comté, 16 route de Gray, 25030 Besançon Cedex (France); Ounoughi, N. [Laboratoire Chrono-Environnement, UMR CNRS 6249, Université de Franche-Comté, 16 route de Gray, 25030 Besançon Cedex (France); Laboratoire de Physique des Rayonnements et Applications, Université de Jijel, B.P. 98 Ouled Aissa, Jijel 18000 (Algeria); Belafrites, A. [Laboratoire de Physique des Rayonnements et Applications, Université de Jijel, B.P. 98 Ouled Aissa, Jijel 18000 (Algeria)

    2014-08-15

    We report the design of a millimeter-sized parallel plate free-air ionization chamber (IC) aimed at determining the absolute air kerma rate of an ultra-soft X-ray beam (E = 1.5 keV). The size of the IC was determined so that the measurement volume satisfies the condition of charged-particle equilibrium. The correction factors necessary to properly measure the absolute kerma using the IC have been established. Particular attention was given to the determination of the effective mean energy for the 1.5 keV photons using the PENELOPE code. Other correction factors were determined by means of computer simulation (COMSOL™and FLUKA). Measurements of air kerma rates under specific operating parameters of the lab-bench X-ray source have been performed at various distances from that source and compared to Monte Carlo calculations. We show that the developed ionization chamber makes it possible to determine accurate photon fluence rates in routine work and will constitute substantial time-savings for future radiobiological experiments based on the use of ultra-soft X-rays.

  10. Determination of the air attenuation and electronic loss for the free air concentric cylinders ionization chamber

    International Nuclear Information System (INIS)

    Along the latest years, the LNMRI has been proceeding a continuous research work with a concentric cylinders type free air ionizing chamber (VICTOREEN, model 481), aiming to establish it as a new national standard, and, as a consequence, replace the worldwide accepted secondary standard, calibrated by PTB. Taking into account that the absolute determination of kerma in air with a free air ionizing chamber implies the acquirement of a number of correction factors. The main objective of the present work comprises the determination of the two factors, specifically, electronic loss (ke) and air attenuation (ka). The correction factors were obtained through mammography qualities reference spectrum, using Monte Carlo simulation method. The Penelope code was used in the simulation procedures. Simulations took place in two stages, the acquirement of specters related to the qualities of interest (mammography) with the x ray tube (Pantak, model HF160 e Panalytical, model XRF window), and the free-air ionization chamber. The data were compared to those related to the BIPM chamber, to electronic loss were not detected. The comparison between air attenuation factors was obtained data bellow 0.13%. (author)

  11. What the Index Medicus indexes, and why.

    Science.gov (United States)

    Truelson, S D

    1966-10-01

    The main criterion for selecting journals for indexing in Index Medicus, and thereby largely in MEDLARS, is quality. Subject scope varies with the voiced needs of the biomedical community. The Index aims to cover the best journals in all relevant subject fields, but the percentage of journals on a subject indexed depends on the quality of each journal. Country and language coverage depends on quality, even in the case of the best journals of each, although American biases may affect such selection. While a number of guidelines exist for identifying quality journals, information necessary to apply them confidently is often difficult to obtain. The National Library of Medicine is advised by an Ad Hoc Panel on the Selection of Journals for Index Medicus, composed both of NLM officers and extramural members. Criticism has been voiced that too many titles are indexed, compared with titles actually used, but no meaningful statistics of use exist which can identify titles which should be excluded from indexing. Continuing suggestions from users regarding titles indexed would benefit everyone. PMID:5922258

  12. 174 Reduction in Allergic Rhinitis Index by Decreasing Aero-Allergens and Malodor Causing Volatile Organic Compounds by Luna Air Purifiers Using Photo-Catalytic Oxidation (PCO) Technology

    OpenAIRE

    Ghosh, Nabarun; Aguaiza, Cristina; Guzman, Alicia; Chudasama, Jay; Bennert, Jeff; Das, A. B.

    2012-01-01

    Background The quality of the environment within buildings is a topic of major importance for public health. Breathing pure and clean air allows us to think more clearly, sleep more soundly, and stay healthier. Studies show that we receive 56% of our energy from the air we breathe, more than from water and food combined. On average we breathe 37 pounds of air a day. It has been established that the use of negative ions in a purification system is an effective means of eradicating aeroallergen...

  13. Refractive index of plant cell walls

    Science.gov (United States)

    Gausman, H. W.; Allen, W. A.; Escobar, D. E.

    1974-01-01

    Air was replaced with media of higher refractive indices by vacuum infiltration in leaves of cucumber, blackeye pea, tomato, and string bean plants, and reflectance of noninfiltrated and infiltrated leaves was spectrophotometrically measured. Infiltrated leaves reflected less light than noninfiltrated leaves over the 500-2500-nm wavelength interval because cell wall-air interfaces were partly eliminated. Minimal reflectance should occur when the average refractive index of plant cell walls was matched by the infiltrating fluid. Although refractive indices that resulted in minimal reflectance differed among the four plant genera, an average value of 1.425 approximates the refractive index of plant cell walls for the four plant genera.

  14. Calculation of conversion coefficients Hp(3)/K air using the PENELOPE Monte Carlo code and comparison with MCNP calculation results

    International Nuclear Information System (INIS)

    The authors report calculations performed using the MNCP and PENELOPE codes to determine the Hp(3)/K air conversion coefficient which allows the Hp(3) dose equivalent to be determined from the measured value of the kerma in the air. They report the definition of the phantom, a 20 cm diameter and 20 cm high cylinder which is considered as representative of a head. Calculations are performed for an energy range corresponding to interventional radiology or cardiology (20 keV-110 keV). Results obtained with both codes are compared

  15. Supersymmetry and index theory

    International Nuclear Information System (INIS)

    The author presents information mainly concerned with the fact that many of the ingredients and results in index theory have very simple analogs in supersymmetric quantum mechanical systems so that using elementary quantum mechanics one can obtain new proofs of the Atiyah-Singer index theorem and related results. Simple ideas on index theorems and characteristic classes are reviewed; simple results on fermion functional integrals are outlined; supersymmetric quantum mechanical systems which appear naturally in dealing with index problems are analyzed; proof of the classical index theorem is presented; the character valued index theorem is derived; and applications of the methods developed here for the computation of anomalies are presented

  16. CENDI Indexing Workshop

    Science.gov (United States)

    1994-01-01

    The CENDI Indexing Workshop held at NASA Headquarters, Two Independence Square, 300 E Street, Washington, DC, on September 21-22, 1994 focused on the following topics: machine aided indexing, indexing quality, an indexing pilot project, the MedIndEx Prototype, Department of Energy/Office of Scientific and Technical Information indexing activities, high-tech coding structures, category indexing schemes, and the Government Information Locator Service. This publication consists mostly of viewgraphs related to the above noted topics. In an appendix is a description of the Government Information Locator Service.

  17. Master Veteran Index (MVI)

    Data.gov (United States)

    Department of Veterans Affairs — As of June 28, 2010, the Master Veteran Index (MVI) database based on the enhanced Master Patient Index (MPI) is the authoritative identity service within the VA,...

  18. UV Index Widget

    Data.gov (United States)

    U.S. Environmental Protection Agency — The UV Index Widget displays the ultraviolet (UV) Index providing a daily forecast of the expected risk of overexposure to the sun for a user-specified area of...

  19. UV Index Widget

    Data.gov (United States)

    U.S. Environmental Protection Agency — The UV Index Widget displays the ultraviolet (UV) Index providing a daily forecast of the expected risk of overexposure to the sun for a user-specified area of...

  20. American Samoa ESI: INDEX (Index Polygons)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains vector polygons representing the boundaries of all the hardcopy cartographic products produced as part of the Environmental Sensitivity Index...

  1. The Europe 2020 Index

    Science.gov (United States)

    Pasimeni, Paolo

    2013-01-01

    This paper presents a new index to quantify, measure and monitor the progress towards the objectives of the Europe 2020 strategy. This index is based on a set of relevant, accepted, credible, easy to monitor and robust indicators presented by the European Commission at the time the strategy was launched. The internal analysis of the index shows…

  2. Machine-Aided Indexing.

    Science.gov (United States)

    Jacobs, Charles R.

    Progress is reported at the 1,000,000 word level on the development of a partial syntatic analysis technique for indexing text. A new indexing subroutine for hyphens is provided. New grammars written and programmed for Machine Aided Indexing (MAI) are discussed. (ED 069 290 is a related document) (Author)

  3. Stamping Forming Quality Index

    Directory of Open Access Journals (Sweden)

    Yanping Zheng

    2013-01-01

    Full Text Available The study proposes that stamping forming quality index should include defect quality index and thickness variation uniformity quality index and different types of stamping parts focus on different defect quality index .Moreover, the fracture and wrinkle quality index can be demonstrated by the distance between the major strain of the simulation unit and the critical curve of the fracture and wrinkle trend in FLD, while thickness variation uniformity quality index can be expressed by variance of sheet metal thinning rate. It takes the automobile back plate reinforcement as the example, select stamping quality index as optimization objectives and constraint conditions based on numerical simulation technology, then apply the technical means that contain with orthogonal test design, neural network and genetic algorithm to optimize the process variables. The result indicates that the method of this study is feasible and effective and has application value in engineering.

  4. Air Pollution

    Science.gov (United States)

    Air pollution is a mixture of solid particles and gases in the air. Car emissions, chemicals from factories, dust, ... a gas, is a major part of air pollution in cities. When ozone forms air pollution, it's ...

  5. Air quality indices : a review

    International Nuclear Information System (INIS)

    Pollution Probe presents some background information that will help in the development of a national Air Quality Index (AQI) in Canada. This report examines the issues that should be addressed in revising the national Index of the Quality of Air (IQUA) or creating a new national Air Quality Index. The IQUA was devised in 1976 and provides Canadians with real-time information on the state of community air quality by including major pollutants and their synergies. It is currently being used for air quality management plans and air quality alert systems. At the same time that the IQUA was devised, the United States Environmental Protection Agency (US EPA) produced a parallel air quality index known as the Pollution Standard Index (PSI) which incorporated 5 criteria pollutants (particulate matter, sulphur dioxide, carbon monoxide, nitrogen oxide and ground level ozone) for which national health-based standards were devised. In 1999, the US EPA renamed their index the Air Quality Index (AQI) and made revisions to the primary health-based national ambient air quality standards for ground-level ozone and particulate matter. Separate values for PM2.5 and PM10 were incorporated and mandatory reporting was required for metropolitan areas with populations of 350,000 or more. Similarly, the IQUA has undergone major developments that affect the validity of the index, including: rejection by the Working Group on Air Quality Objectives and Guidelines of the previous maximum desirable and maximum acceptable air quality criteria, recognition that standards for many of the contaminants are outdated, developing more sensitive instrumentation for real-time monitoring of contaminants. This report also describes the use of the national short term Air Quality Index by provincial, territorial and local authorities in Canada. Pollution Probe recommends setting up a mechanism to review and revise IQUA on a regular basis that would incorporate governments, the medical profession, special public interest groups, as well as environmental and industrial interest groups. It also recommends that new ways should be developed to facilitate a comparison between IQUA and AQI readings with those for AQI in the United States, especially in border communities. 7 tabs

  6. Photon and neutron fluence-to-kerma conversion factors for ICRP-1975 reference man using improved elemental compositions for bone and marrow of the skeleton

    International Nuclear Information System (INIS)

    Findings of a recent ORNL review, and of other reviews, which have been discussed at the Late Effects Workshop on Dosimetry of Atomic Bomb Survivors, 29th Annual Meeting of the Radiation Research Society, Minneapolis, Minnesota, 31 May 1981, and the Symposium on Reevaluations of Dosimetric Factors, Hiroshima and Nagasaki, US Department of Energy, Germantown, Maryland, 5 and 6 September 1981, have clearly established a need to revise the dosimetry for the A-bomb survivors. This effort will involve several divisions at ORNL, several other national laboratories, and several consulting firms. One of the main tasks of the Health and Safety Research Division at ORNL is to provide revised estimates of various organ-dose parameters related to a survivor's neutron and gamma-ray exposures. The objectives of the work summarized in this report were: (a) to better define the elemental composition of various skeletal components of ICRP-1975 Reference Man, and (b) to investigate photon and neutron fluence-to-kerma conversion factors for various total-body and organ-tissue components of ICRP-1975 Reference man as revised here. Scaled down mathematical descriptions of the volumes and shapes of the total body and internal organs of Reference Man will be used, of course, in the organ-dose calculations for A-bomb survivors

  7. ZZ DLC-14 AIR, Group Constant Library of Secondary Gamma Transport in Air for ANISN Calculation

    International Nuclear Information System (INIS)

    1 - Nature of physical problem solved: Format: ANISN, DOT, MORSE (FIDO format); Number of groups: 22 neutron / 18 gamma-ray; Nuclides: air; Origin: ENDF/B for neutron cross sections, DLC-4/HPIC for gamma-ray and DLC-12/POPLIB for secondary gamma-ray production. Weighting spectrum: 1/E for neutron cross sections. The basic idea behind the distribution of this ANISN input data is to allow potential users to repeat the ANISN calculations reported in ref. (1). It is felt that it will be more economical to repeat the calculations rather than to distribute the results of the Straker-Gritzner (1) calculations. However, the cross section part of the data can actually be used in DOT or MORSE or any transport code which will accept input cross section in the FIDO format. 2 - Method of solution: The sample input data for ANISN are for a P5, S16 calculation of the transport of neutrons and secondary gamma-rays from a 12.2 to 15 MeV point neutron source in an infinite air medium. The source is actually uniformly distributed in the first interval (500 cm radius) of a spherical medium of air with radius 3005 meters. The problem is set up for calculating various 'detector responses' by means of the 'activity' option available with ANISN. This is accomplished by providing a cross section table for a 'material' which has detector responses in certain table positions. Then the inclusion of appropriate input data for 22$ and 23$ arrays causes the group fluxes to be multiplied by the group response function values to give the desired answer. The neutron detector responses calculated by this sample problem are Henderson tissue dose, Snyder-Neufeld dose, tissue kerma, and air kerma. The gamma-ray response functions calculated are Henderson tissue dose and air kerma. The neutron cross sections were first reduced from point data from ENDF/B to a 104 fine group structure with a modified version of CSP, assuming a 1/E weighting factor. The gamma-ray data were reduced from point data from DLC-4/HPIC to an 18 group structure using MUG. The POPOP-4 code was used to convert secondary gamma-ray production data from DLC-12/POPLIB to neutron-to-gamma-ray group transfer cross sections. The coupled set (104 neutron, 18 gamma-ray groups) was then collapsed to 22 neutron and 18 gamma-ray groups with ANISN, using as the weighting function the spectrum from a spatially uniform source of 14 MeV neutrons in an infinite air medium with a density of 1.11 mg/cc. The resulting data are coupled macroscopic multigroup, P5 expansion cross sections for air punched on cards and suitable for input to the ANISN code

  8. A Tourism Conditions Index

    OpenAIRE

    Chang, Chia-lin; Hsu, Hui-Kuang; McAleer, Michael

    2014-01-01

    This paper uses monthly data from April 2005 to August 2013 for Taiwan to propose a novel tourism indicator, namely the Tourism Conditions Index (TCI). TCI accounts for the spillover weights based on the Granger causality test and estimates of the multivariate BEKK model for four TCI indicators to predict specific tourism and economic environmental indicators for Taiwan. The foundation of the TCI is the Financial Conditions Index (FCI), which is derived from the Monetary Conditions Index (MCI...

  9. Supplement: Commodity Index Report

    Data.gov (United States)

    Commodity Futures Trading Commission — Shows index traders in selected agricultural markets. These traders are drawn from the noncommercial and commercial categories. The noncommercial category includes...

  10. EJSCREEN Supplementary Indexes 2015 Internal

    Data.gov (United States)

    U.S. Environmental Protection Agency — There are 60 supplementary EJ Indexes in EJSCREEN that are divided into 5 categories: EJ Index with supplementary demographic index, Supplementary EJ Index 1 with...

  11. EJSCREEN Supplementary Indexes 2015 Internal

    Data.gov (United States)

    U.S. Environmental Protection Agency — There are 60 supplementary EJ Indexes in EJSCREEN that are divided into 5 categories: EJ Index with supplementary demographic index, Supplementary EJ Index 1 with...

  12. Aktivitas Hipolipidemik dan Indeks Aterogenik yang Rendah Ekstrak Air Daun Tapak Dara pada Tikus Hiperkolesterolemia (HYPOLIPIDEMIC ACTIVITY AND LOW ATHEROGENIC INDEX OF AQUEOUS LEAF EXTRACTS OF CATHARANTHUS ROSEUS IN HYPERCHOLESTEROLEMIC RATS

    Directory of Open Access Journals (Sweden)

    I Nyoman Suarsana

    2016-01-01

    Full Text Available Catharanthus roseus is one plant recognized as medical potential which can decrease cholesterol. Thepresent study was carried out to evaluate the effect of aqueous leaf extracts of C. roseus on plasma lipidprofil levels in rats cholesterol rich diet and atherogenic index. This study was carried out on 15 SpraqueDawley male rats randomly distributed into five groups (n=3. Rats hypercholesterolemic wereadministrated cholesterol rich diet containing 1% (w/w. Normal control group with normal diet whitoutextracts (K1, positive control hypercholesterolemic group (K2 with cholesterol rich diet whitout extracts,and others three groups (K3-K5 were feed high cholesterol and 1 mL of aqueous leaf extracts of C. roseuswith a dose of 20% (w/v, 40% (w/v and 80% (w/v respectively, administered twice daily 1 mL orally.Treatment was given for 28 days. After treatment, the plasma lipids profile such cholesterol total, highdensity lipoprotein (HDL, low density lipoprotein (LDL, triglyceride (TGA level were measured. Theresults showed that during the period of treatment with cholesterol rich diet have produced under condition hypercholesterolemic of rats with average cholesterol levels of 124.33 ± 4.04 mg/dL (K2 group. Treatmentwith extract dose of 80% showed the best results among the other doses in reducing levels of total cholesterol,triglycerides, LDL and raise HDL levels. Extract treatment dose of 80% up to four weeks resulted incholesterol total (79.33±3.51 mg/dL, TGA (72.33±6.65 mg/dL, HDL (55.00±3.60 mg/dL, and LDL(9.87±5.34mg/dL. In addition, value ratio of cholesterol:HDL was 1.4: 1 and atherogenic index value was0.44. These results suggest that extracts of leaf C. roseus optimum doses 80% (w/v has hipolipidemicactivity in hypercholesterolemic rats and it has low atherogenic index value.

  13. Global Ecosystem Restoration Index

    DEFF Research Database (Denmark)

    Fernandez, Miguel; Garcia, Monica; Fernandez, Nestor

    The Global ecosystem restoration index (GERI) is a composite index that integrates structural and functional aspects of the ecosystem restoration process. These elements are evaluated through a window that looks into a baseline for degraded ecosystems with the objective to assess restoration...

  14. Estimation of entrance dose on chest radiographs according to the exposure index on Computerized Radiology System: preliminary results; Estimativa de dose de entrada a partir do indice de exposicao em sistema CR: resultados preliminares

    Energy Technology Data Exchange (ETDEWEB)

    Donomai, Luana Kaoru; Jornada, Tiago da Silva; Daros, Kellen Adriana Curci, E-mail: luana.donomai@gmail.com, E-mail: tiagosjornada@gmail.com, E-mail: daros.kellen@unifesp.br [Universidade Federal de Sao Paulo (UNIFESP), Sao Paulo, SP (Brazil)

    2014-07-01

    Digital radiology has improved image quality in radiographs in comparison to screen/film systems though the visual control of the quantity of radiation involved on these exams became more demanding due to the low perception of over and underexposed images. Therefore, this study aims to analyze the exposure index (EI) from chest examinations and relate them to the entrance skin dose. Indices from 29 patients and kerma entrance dose were correlated. A correlation coefficient equal to 0,6881 was calculated. EI and entrance dose are correlated positive and moderately, indicating the relevance to deepen the subject. (author)

  15. Sensitivity of coefficients for converting entrance surface dose and kerma-area product to effective dose and energy imparted to the patient

    Science.gov (United States)

    Wise, K. N.; Sandborg, M.; Persliden, J.; Alm Carlsson, G.

    1999-08-01

    We investigate the sensitivity of the conversions from entrance surface dose (ESD) or kerma-area product (KAP) to effective dose (E) or to energy imparted to the patient () to the likely variations in tube potential, field size, patient size and sex which occur in clinical work. As part of a factorial design study for chest and lumbar spine examinations, the tube potentials were varied to be ±10% of the typical values for the examinations while field sizes and the positions of the field centres were varied to be representative of values drawn from measurements on patient images. Variation over sex and patient size was based on anthropomorphic phantoms representing males and females of ages 15 years (small adult) and 21 years (reference adult). All the conversion coefficients were estimated using a mathematical phantom programmed with the Monte Carlo code EGS4 for all factor combinations and analysed statistically to derive factor effects. In general, the factors studied behaved independently in the sense that interaction of the physical factors generally gave no more than a 5% variation in a conversion coefficient. Taken together, variation of patient size, sex, field size and field position can lead to significant variation of E/KAP by up to a factor of 2, of E/ESD by up to a factor of 3, of /KAP by a factor of 1.3 and of /ESD by up to a factor of 2. While KAP is preferred to determine , the results show no strong preference of KAP over ESD in determining E. The mean absorbed dose in the patient obtained by dividing (determined using KAP) by the patient's mass was found to be the most robust measure of E.

  16. Sensitivity of coefficients for converting entrance surface dose and kerma-area product to effective dose and energy imparted to the patient

    International Nuclear Information System (INIS)

    We investigate the sensitivity of the conversions from entrance surface dose (ESD) or kerma-area product (KAP) to effective dose (E) or to energy imparted to the patient (?) to the likely variations in tube potential, field size, patient size and sex which occur in clinical work. As part of a factorial design study for chest and lumbar spine examinations, the tube potentials were varied to be ±10% of the typical values for the examinations while field sizes and the positions of the field centres were varied to be representative of values drawn from measurements on patient images. Variation over sex and patient size was based on anthropomorphic phantoms representing males and females of ages 15 years (small adult) and 21 years (reference adult). All the conversion coefficients were estimated using a mathematical phantom programmed with the Monte Carlo code EGS4 for all factor combinations and analysed statistically to derive factor effects. In general, the factors studied behaved independently in the sense that interaction of the physical factors generally gave no more than a 5% variation in a conversion coefficient. Taken together, variation of patient size, sex, field size and field position can lead to significant variation of E/KAP by up to a factor of 2, of E/ESD by up to a factor of 3, of ?/KAP by a factor of 1.3 and of ?/ESD by up to a factor of 2. While KAP is preferred to determine ?, the results show no strong preference of KAP over ESD in determining E. The mean absorbed dose D-bar in the patient obtained by dividing ? (determined using KAP) by the patient's mass was found to be the most robust measure of E. (author)

  17. Supersymmetric Berry index

    CERN Document Server

    Ilinskii, K N; Melezhik, V S; Ilinski, K N; Kalinin, G V; Melezhik, V V

    1994-01-01

    We revise the sequences of SUSY for a cyclic adiabatic evolution governed by the supersymmetric quantum mechanical Hamiltonian. The condition (supersymmetric adiabatic evolution) under which the supersymmetric reductions of Berry (nondegenerated case) or Wilczek-Zee (degenerated case) phases of superpartners are taking place is pointed out. The analogue of Witten index (supersymmetric Berry index) is determined. As the examples of suggested concept of supersymmetric adiabatic evolution the Holomorphic quantum mechanics on complex plane and Meromorphic quantum mechanics on Riemann surface are considered. The supersymmetric Berry indexes for the models are calculated.

  18. Concurrency Control for Adaptive Indexing

    CERN Document Server

    Graefe, Goetz; Idreos, Stratos; Kuno, Harumi; Manegold, Stefan

    2012-01-01

    Adaptive indexing initializes and optimizes indexes incrementally, as a side effect of query processing. The goal is to achieve the benefits of indexes while hiding or minimizing the costs of index creation. However, index-optimizing side effects seem to turn read-only queries into update transactions that might, for example, create lock contention. This paper studies concurrency control in the context of adaptive indexing. We show that the design and implementation of adaptive indexing rigorously separates index structures from index contents; this relaxes the constraints and requirements during adaptive indexing compared to those of traditional index updates. Our design adapts to the fact that an adaptive index is refined continuously, and exploits any concurrency opportunities in a dynamic way. A detailed experimental analysis demonstrates that (a) adaptive indexing maintains its adaptive properties even when running concurrent queries, (b) adaptive indexing can exploit the opportunity for parallelism due ...

  19. Index of Glossary Terms

    Science.gov (United States)

    ... In the News Article Index Tests Conditions Screening Features News Glossary About This Site Send Us Your Comments For Health Professionals Get the Mobile App iTunes | Android | Kindle Follow Us Understanding Your Tests | Inside the ...

  20. Arizona - Social Vulnerability Index

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Social Vulnerability Index is derived from the 2000 US Census data. The fields included are percent minority, median household income, age (under 18 and over...

  1. Regional Snowfall Index (RSI)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Climatic Data Center is now producing the Regional Snowfall Index (RSI) for significant snowstorms that impact the eastern two thirds of the U.S....

  2. National Death Index

    Data.gov (United States)

    U.S. Department of Health & Human Services — The National Death Index (NDI) is a centralized database of death record information on file in state vital statistics offices. Working with these state offices,...

  3. Cataloguing and Indexing Activities

    Science.gov (United States)

    Bakewell, K. G. B.

    1971-01-01

    Comments are given on: the 18th edition of the Decimal Classification, the MARC Automated Serials System (MASS) project, and the Cataloging and Indexing Group's survey of catalog use. (11 references) (NH)

  4. Vegetation Drought Response Index

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — VegDRI, short for Vegetation Drought Response Index, is a drought-monitoring tool developed by scientists at EROS in collaboration with the National Drought...

  5. TOMS Absorbing Aerosol Index

    Data.gov (United States)

    Washington University St Louis — TOMS_AI_G is an aerosol related dataset derived from the Total Ozone Monitoring Satellite (TOMS) Sensor. The TOMS aerosol index arises from absorbing aerosols such...

  6. Lattice Index Coding

    OpenAIRE

    Natarajan, Lakshmi; Hong, Yi; Viterbo, Emanuele

    2014-01-01

    The index coding problem involves a sender with K messages to be transmitted across a broadcast channel, and a set of receivers each of which demands a subset of the K messages while having prior knowledge of a different subset as side information. We consider the specific case of noisy index coding where the broadcast channel is Gaussian and every receiver demands all the messages from the source. Instances of this communication problem arise in wireless relay networks, sen...

  7. Dow's chemical exposure index guide

    International Nuclear Information System (INIS)

    A number of events in the 1970's and 1980's impacted the course of process safety. Incidents such as Flixborough, Seveso, Three-Mile Island, and Bhopal are well known throughout industry and are recognized as examples of major disasters. Even though events leading up to these disasters were completely different they had one common element between them: a substance was released from a manufacturing unit, became airborne and presented a hazard of such magnitude as to place the safety of both employees and the surrounding public in jeopardy. As a result, industry became increasingly concerned regarding potential loss, in human and economic terms, as plants and equipment grew in size. The Flixborough incident raised the level of concern for process safety, particularly in terms of the hazards presented by fire and explosion. Seveso and Three-Mile Island emphasized the need to consider far-field exposure. The Bhopal incident created an urgent need to recognize and understand the expected downwind impact of potential releases of acutely toxic substances to the air. In order to meet this need, the Dow Chemical Company, a recognized leader in the area of safety and loss prevention, presented a Chemical Exposure Index in 1986. AIChE has recently published an updated version entitled Dow's Chemical Exposure Index Guide. 7 refs., 5 figs

  8. CHEMICAL AND BIOLOGICAL AIR POLLUTANTS, AS PARAMETERS OF COMPLEX AIR QUALITY INDICES

    OpenAIRE

    TEKLA EÖTVÖS; LÁSZLÓ MAKRA

    2007-01-01

    Human health is essentially influenced by air quality. Atmospheric air in residential areas contains many pollutants. The monitoring and the plain publishing of the measured values are important both for the authorities and the public. Air quality is often characterized by constructing air quality indices, and these indices are used to inform the public. The construction of an advanced air quality index is usually done by averaging the measured data usually in time and space; hereby important...

  9. Characterization of the new free-air primary standard for low-energy X-rays at CMI

    International Nuclear Information System (INIS)

    In 2011 a decision was made by Czech Metrology Institute to build a free-air ionization chamber (FAC) intended to be used as a primary standard of air kerma rate for low-energy X-rays (photon energy below 50 keV, including mammography X-ray qualities) in order to replace the currently used secondary ionization chamber and to decrease the uncertainty of air kerma reference value. In the period 2011–2012, the FAC has been designed, manufactured and put into operation. Its performance was tested using a calibrated secondary chamber and then by an informal comparison with a national primary standard of BEV (Austria). Physical characteristics of the FAC are described and individual correction factors are discussed focusing on computational methods utilized in their estimation. Summary of the correction factors with the uncertainty budget is presented. - Highlights: • A new primary standard for low-energy X-ray beam constructed at CMI. • Correction factors calculated by MCNPX simulations. • The chamber performance tested by an informal comparison with BEV (Austria). • The chamber considered ready for key comparison and standardization of X-ray beams

  10. Computaional Complexity Analysis on Water Quality Index

    OpenAIRE

    Anni Prabakaran & Dr. B. Poorna

    2012-01-01

    The computational algorithms are used to determine the features and applications from large data sets in real time environment. The computational applications are also used in environmental computing to evaluate the degree of air, water and sound pollutions and measures of prevention. The computational process of water quality index (WQI) is determined through analysis of water quality attributes. Though existing methods produced WQI with certain water quality attributes according to the natu...

  11. A Ventilation Index for Tropical Cyclones

    OpenAIRE

    Tang, Brian; Emanuel, Kerry Andrew

    2012-01-01

    An important environmental control of both tropical cyclone intensity and genesis is vertical wind shear. One hypothesized pathway by which vertical shear affects tropical cyclones is midlevel ventilation—or the flux of low-entropy air into the center of the tropical cyclone. Based on a theoretical framework, a ventilation index is introduced that is equal to the environmental vertical wind shear multiplied by the nondimensional midlevel entropy deficit divided by the potential intensity. The...

  12. SOIL-RAD - A computer program to calculate air kerma, ambient dose rate and effective dose rate due to photons emitted by radionuclides distributed in soil or on the soil-air surface

    OpenAIRE

    Blaauboer RO

    2012-01-01

    In verschillende onderzoeken is er behoefte aan een geautomatiseerde methode voor het bepalen van de dosis ten gevolge van externe bestraling door radionucliden in en op de bodem. Hierbij kan gedacht worden aan migratie van fallout in de bodem, berekenen van de afschermende werking van de bodem bij het opbrengen van een afdeklaag over een laag ertsafval en het dosistempo door de natuurlijke aanwezigheid van radionucliden. In het kader van een onderzoek naar het gebruik...

  13. Estimating the Upcrossings Index

    CERN Document Server

    Sebastião, João Renato; Ferreira, Helena; Pereira, Luísa

    2012-01-01

    For stationary sequences, under general local and asymptotic dependence restrictions, any limiting point process for time normalized upcrossings of high levels is a compound Poisson process, i.e., there is a clustering of high upcrossings, where the underlying Poisson points represent cluster positions, and the multiplicities correspond to cluster sizes. For such classes of stationary sequences there exists the upcrossings index $\\eta,$ $0\\leq \\eta\\leq 1,$ which is directly related to the extremal index $\\theta,$ $0\\leq \\theta\\leq 1,$ for suitable high levels. In this paper we consider the problem of estimating the upcrossings index $\\eta$ for a class of stationary sequences satisfying a mild oscillation restriction. For the proposed estimator, properties such as consistency and asymptotic normality are studied. Finally, the performance of the estimator is assessed through simulation studies for autoregressive processes and case studies in the fields of environment and finance.

  14. Upgrading the Wiener index

    Directory of Open Access Journals (Sweden)

    PABLO PERUZZO

    2002-10-01

    Full Text Available The Wiener index W is the oldest molecular-graph-based structure-descriptor. It is defined as the sum of the distances of all pairs of vertices of the molecular graph G, where the distance is the number of edges in the shortest path connecting the respective vertices, and where G is the hydrogen-depleted molecular graph. This seemingly very simple topological index could be "upgraded" (a by using as the distance the sum of the bond lengths along the shortest path, or (b by using the Euclidean distance between the respective pairs of atoms. Each of these "upgraded" Wiener indices could be computed either (a for the hydrogen-depleted or (b for the hydrogen-filled molecular graph. We provide examples showing that none of the modifications (aa, (ab, (ba, (bb yields better results than the ordinary Wiener index, and that there is a very good linear correlation between W and its "upgraded" variants.

  15. Sustainability index for Taipei

    International Nuclear Information System (INIS)

    Sustainability indicators are an effective means of determining whether a city is moving towards sustainable development (SD). After considering the characteristics of Taipei, Taiwan, discussions with experts, scholars and government departments and an exhaustive literature review, this study selected 51 sustainability indicators corresponding to the socio-economic characteristic of Taipei City. Such indicators should be regarded as a basis for assessing SD in Taipei City. The 51 indicators are classified into economic, social, environmental and institutional dimensions. Furthermore, statistical data is adopted to identify the trend of SD from 1994 to 2004. Moreover, the sustainability index is calculated for the four dimensions and for Taipei as a whole. Analysis results demonstrate that social and environmental indicators are moving towards SD, while economic and institutional dimensions are performing relatively poorly. However, since 2002, the economic sustainability index has gradually moved towards SD. Overall, the Taipei sustainability index indicates a gradual trend towards sustainable development during the past 11 years

  16. 2005 Environmental Sustainability Index (ESI)

    Data.gov (United States)

    National Aeronautics and Space Administration — The 2005 Environmental Sustainability Index (ESI) is a measure of overall progress towards environmental sustainability, developed for 146 countries. The index...

  17. Fourth Indexing Course

    Directory of Open Access Journals (Sweden)

    Director DESIDOC

    1982-04-01

    Full Text Available The fourth training course in 'Indexing' was organised by DESIDOC at Metcalfe House, Delhi from 24 Feb to 6 Mar 1982. The course was intended for information personnel of DRDO Labs/Estts located in the north zone. The curriculum covered various aspects of indexing techniques and systems including computer processing. Besides the lectures and practical assignments, audiovisual demonstration on NTIS services was also screened. Visits to DRDO Computer Centre to familiarise the participants with the working of the computer, and INSDOC/National Science Library were also arranged.

  18. Indexing Moving Points

    DEFF Research Database (Denmark)

    Agarwal, Pankaj K.; Arge, Lars Allan; Erickson, Jeff

    2003-01-01

    We propose three indexing schemes for storing a set S of N points in the plane, each moving along a linear trajectory, so that any query of the following form can be answered quickly: Given a rectangle R and a real value t, report all K points of S that lie inside R at time t. We first present an indexing structure that, for any given constant >0, uses O(N/B) disk blocks and answers a query in O((N/B)1/2+ +K/B) I/Os, where B is the block size. It can also report all the points of S that lie insi...

  19. Practical Hydrogen Loading of Air Silica Fibres

    DEFF Research Database (Denmark)

    Sørensen, Henrik Rokkjær; Jensen, Jesper Bevensee; Jensen, Jesper Bo Damm; Bruyere, Frederic; Hansen, Kim P.

    A method for hydrogen-loading air-silica optical fibres has been developed allowing out-diffusion times comparable to standard step-index fibres. Examples of the first grating written in Ge-doped air-silica fibres using a 266nm UV-laser are shown.......A method for hydrogen-loading air-silica optical fibres has been developed allowing out-diffusion times comparable to standard step-index fibres. Examples of the first grating written in Ge-doped air-silica fibres using a 266nm UV-laser are shown....

  20. Glycemic Index Values Database

    Science.gov (United States)

    NCI has developed a listing of Glycemic Index (GI) values for individual foods. Food codes from the USDA Continuing Survey of Food Intakes of Individuals (CSFII) are used as a reference. This file provides GI values for those foods consumed by adults and queried on the DHQ or other FFQs used at NCI.

  1. Well Being Index

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Gallup-Healthways Well-Being Index is the first-ever daily assessment of U.S. residents' health and well-being. By interviewing at least 1,000 U.S. adults every...

  2. An Admissions Accountability Index

    Science.gov (United States)

    Brailey, Lester G.; Jacobs, Les

    1974-01-01

    CUNY's comprehensive data base and its geographic and educational parameters make possible the computation of an Admissions Accountability Index built on an input-output (hours-applications) ratio. It helps staff determine which high schools need and deserve more time and service, and helps high-school advisers compare their results with similar…

  3. Graded-index magnonics

    Science.gov (United States)

    Davies, C. S.; Kruglyak, V. V.

    2015-10-01

    The wave solutions of the Landau-Lifshitz equation (spin waves) are characterized by some of the most complex and peculiar dispersion relations among all waves. For example, the spin-wave ("magnonic") dispersion can range from the parabolic law (typical for a quantum-mechanical electron) at short wavelengths to the nonanalytical linear type (typical for light and acoustic phonons) at long wavelengths. Moreover, the long-wavelength magnonic dispersion has a gap and is inherently anisotropic, being naturally negative for a range of relative orientations between the effective field and the spin-wave wave vector. Nonuniformities in the effective field and magnetization configurations enable the guiding and steering of spin waves in a deliberate manner and therefore represent landscapes of graded refractive index (graded magnonic index). By analogy to the fields of graded-index photonics and transformation optics, the studies of spin waves in graded magnonic landscapes can be united under the umbrella of the graded-index magnonics theme and are reviewed here with focus on the challenges and opportunities ahead of this exciting research direction.

  4. Simulation of Iodine-125 seeds photon spectra in the air by using the Monte Carlo method

    International Nuclear Information System (INIS)

    Viewing the characteristics of the construction of I-125 seed sources, the low energy of the I-125 photons spectra and the large anisotropy of these photons energy fluence, this paper presents a study of those parameters and their influence on the dose calculations during the sources implant, and also the results of the simulation by using the EGS4 Monte Carlo code for the IMC.6711 I-125 seed photon model, produced by the Amersham Healthcare and Instituto de Pesquisas Energeticas da Comissao Nacional de Energia Nuclear. The intensity of the kerma in the air has been calculated based on the photon fluencies for distances ranging from the source surface to 5 cm in air

  5. Clean Air Markets - Quick Facts and Trends

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Quick Facts and Trends module is part of a suite of Clean Air Markets-related tools that are accessible at http://camddataandmaps.epa.gov/gdm/index.cfm. The...

  6. Clean Air Markets - Quick Facts and Trends

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Quick Facts and Trends module is part of a suite of Clean Air Markets-related tools that are accessible at http://camddataandmaps.epa.gov/gdm/index.cfm. The...

  7. Scientific Journal Indexing

    Directory of Open Access Journals (Sweden)

    Getulio Teixeira Batista

    2007-08-01

    Full Text Available It is quite impressive the visibility of online publishing compared to offline. Lawrence (2001 computed the percentage increase across 1,494 venues containing at least five offline and five online articles. Results shown an average of 336% more citations to online articles compared to offline articles published in the same venue. If articles published in the same venue are of similar quality, then they concluded that online articles are more highly cited because of their easier access. Thomson Scientific, traditionally concerned with printed journals, announced on November 28, 2005, the launch of Web Citation Index™, the multidisciplinary citation index of scholarly content from institutional and subject-based repositories (http://scientific.thomson. com/press/2005/8298416/. The Web Citation Index from the abstracting and indexing (A&I connects together pre-print articles, institutional repositories and open access (OA journals (Chillingworth, 2005. Basically all research funds are government granted funds, tax payer’s supported and therefore, results should be made freely available to the community. Free online availability facilitates access to research findings, maximizes interaction among research groups, and optimizes efforts and research funds efficiency. Therefore, Ambi-Água is committed to provide free access to its articles. An important aspect of Ambi-Água is the publication and management system of this journal. It uses the Electronic System for Journal Publishing (SEER - http://www.ibict.br/secao.php?cat=SEER. This system was translated and customized by the Brazilian Institute for Science and Technology Information (IBICT based on the software developed by the Public Knowledge Project (Open Journal Systems of the British Columbia University (http://pkp.sfu.ca/ojs/. The big advantage of using this system is that it is compatible with the OAI-PMH protocol for metadata harvesting what greatly promotes published articles visibility. Currently, there are 687 conformably registered repositories in OAI. The Public Knowledge Project – Open Archives Harvester2. lists Ambi-Água: http://pkp.sfu.ca/harvester2/demo/index.php/browse/ index/677. At the OAI base the URL of Ambi-Água is http://www.agro.unitau.br/ seer/index.php/ambi-agua/oai?verb=Identify. Therefore, all Service Providers are automatically capable of harvesting metadata from Ambi-Água articles.

  8. Harary index - Twelve years later

    OpenAIRE

    Lu?i?, Bono; Mili?evi?, Ante; Nikoli?, Sonja; Nenad TRINAJSTI?

    2002-01-01

    A modification of the Harary index, denoted by H and introduced twelve years ago, is proposed. Unlike the original index, this index, called the modified Harary index and denoted by (m)H, consists of two parts: the first relates to greater contributions of outer bonds and the second to smaller contributions of inner bonds of an alkane, which is in accordance with the chemists' intuition. The Wiener index W Harary index and modified Harary index are compared in the structure-property modeling ...

  9. Fundamental data on environmental gamma-ray fields in the air due to sources in the ground

    International Nuclear Information System (INIS)

    This report documents the extensive results of calculations of gamma-ray fields due to sources distributed in the ground. Air kerma per unit source density at 12 heights up to 300 m above the ground was calculated using a Monte Carlo method for monoenergetic plane sources in and on the ground and for natural radionuclides uniformly distributed in the ground. In case of plane sources, calculations were performed for 18 photon energies from 10 keV to 5 MeV and for 22 source depths expressed in mass per unit area ranging from 0 to 200 g/cm2. For natural nuclides, the whole lines compiled in a recent nuclear data file were taken into account. With respect to kerma in air and fluence of primary photon, the whole calculated results are shown in this report. For double-differential gamma-ray fields, several heights and source depths were selected to demonstrate the features. The calculated data for different soil compositions in energy range up to 100 keV were also shown to give the measure of the effect of soil compositions. (author)

  10. Introduction of a Cooling-Fan Efficiency Index

    DEFF Research Database (Denmark)

    Schiavon, S.; Melikov, Arsen Krikor

    2009-01-01

    In a warm environment, air movement with elevated velocity is a well-known cooling strategy. The local air movement is typically generated by cooling fans (e.g., ceiling fan, table fans, etc.). Appearance, power input, and price are the main parameters considered today when purchasing cooling fans......, while cooling capacity and efficiency of energy use are unknown. To address this knowledge gap, this paper introduces the cooling-fan efficiency (CFE) index, defined as the ratio between the cooling effect (measured with a thermal manikin) generated by the device and its power consumption. The index was...... determined for a ceiling fan, a desk fan, standing fan, and a tower fan in a real office at three room air temperatures and at different fan speed levels. The results reveal that the index is sensitive enough to identify differences in the performance of the cooling devices. A standard method for testing fan...

  11. Refractive index based measurements

    DEFF Research Database (Denmark)

    SØrensen, Henrik SchiØtt Technical University of Denmark,

    In a method for performing a refractive index based measurement of a property of a fluid such as chemical composition or temperature, a chirp in the local spatial frequency of interference fringes of an interference pattern is reduced by mathematical manipulation of the recorded light intensity in the interference pattern or by the physical positioning and arrangement of a detector used for capturing the interference pattern.

  12. Towards Cryptocurrency Index

    OpenAIRE

    Trimborn, Simon

    2015-01-01

    In dieser Thesis wird ein Marktindex konstruiert, wobei neu entwickelte Methoden für solch eine Aufgabe verwendet werden. Die Entscheidung über die Anzahl der Indexteilnehmer wird mithilfe des AIC und BIC Kriteriums getroffen und die Liquiditätsregel wird auf Grundlage der BIS Umfrage ermittelt. Dieser neu entwickelte Index, CRIX, wird dann benutzt, um den Kryptowährungsmarkt gegen Bitcoins und andere Märkte zu vergleichen. Es wurde herausgefunden, dass dieser Markt wesentlich risikoreicher i...

  13. Potential vorticity index

    Science.gov (United States)

    Barcilon, Albert; Weng, Hengyi

    1991-01-01

    Based on the European Center For Medium Range Weather Forecasting (ECMWF) First Global Atmospheric Research Program Global Experiment (FGGE) IIIb data set in the 1978 to 1979 winter, a potential vorticity (PV) index was defined as a measure of the zonally averaged, mid-latitude PV gradient on the 300 K isentropic surface in the Northern Hemisphere. The evolution of that index and its relation to teleconnection patterns of 500 mb geopotential height anomaly are studied. The results of the temporal and spatial variation of blocking and cyclogenesis in the 1978 to 1979 winter and its relation to global and local PV gradients were obtained. Complex empirical orthogonal function (EOF) analyses were performed, using the same FGGE data set for the 1978 to 1979 winter, for a representative high latitude band and mid latitude band geopotential height anomalies at 500 mb, phi sub h, phi sub m, and PV gradient at 300 K, delta(Q), at each longitude for the three month period. The focus of current research is the following: (1) to perform Fourier analyses for the first three EOF's of phi sub h, phi sub m, and delta(Q) at given latitude bands, and to find the dominant wavenumbers and frequencies which are responsible for these EOF's; (2) to compare the results from EOF and Fourier analyses which will be used to explore the relations of blocking and cyclogensis with local and global PV gradients; and (3) to study the time dependence of the local PV gradients and relate it to the PV index vacillation cycles observed in the PV index cycle.

  14. Indexing for summary queries

    DEFF Research Database (Denmark)

    Yi, Ke; Wang, Lu; Wei, Zhewei

    2014-01-01

    Database queries can be broadly classified into two categories: reporting queries and aggregation queries. The former retrieves a collection of records from the database that match the query's conditions, while the latter returns an aggregate, such as count, sum, average, or max (min), of a....... Our indexes require linear space and extract a summary with the optimal or near-optimal query cost. We illustrate the efficiency and usefulness of our designs through extensive experiments and a system demonstration....

  15. Indexing Cost Sensitive Prediction

    OpenAIRE

    Battle, Leilani; Benson, Edward; Parameswaran, Aditya; Wu, Eugene

    2014-01-01

    Predictive models are often used for real-time decision making. However, typical machine learning techniques ignore feature evaluation cost, and focus solely on the accuracy of the machine learning models obtained utilizing all the features available. We develop algorithms and indexes to support cost-sensitive prediction, i.e., making decisions using machine learning models taking feature evaluation cost into account. Given an item and a online computation cost (i.e., time) ...

  16. Indexical Hybrid Tense Logic

    DEFF Research Database (Denmark)

    Blackburn, Patrick Rowan; Jørgensen, Klaus Frovin

    2012-01-01

    In this paper we explore the logic of now, yesterday, today and tomorrow by combining the semantic approach to indexicality pioneered by Hans Kamp [9] and refined by David Kaplan [10] with hybrid tense logic. We first introduce a special now nominal (our @now corresponds to Kamp’s original now operator N) and prove completeness results for both logical and contextual validity. We then add propositional constants to handle yesterday, today and tomorrow; our system correctly treats sentences like ...

  17. Refractive index based measurements

    DEFF Research Database (Denmark)

    In a method for performing a refractive index based measurement of a property of a fluid such as chemical composition or temperature by observing an apparent angular shift in an interference fringe pattern produced by back or forward scattering interferometry, ambiguities in the measurement caused by the apparent shift being consistent with one of a number of numerical possibilities for the real shift which differ by 2n are resolved by combining measurements performed on the same sample using li...

  18. '76 EQ Index

    Science.gov (United States)

    National Wildlife, 1976

    1976-01-01

    This report evaluates the environmental quality of the United States. The analysis reveals that wildlife, soil, water, minerals, and living space indices have slid downward from 1969 to 1975. Only air quality slightly improved and timber remained steady. Despite this pessimistic picture, public support for environmental goals is still high. (MR)

  19. Introduction of a Cooling-Fan Efficiency Index

    DEFF Research Database (Denmark)

    Schiavon, S.; Melikov, Arsen Krikor

    2009-01-01

    In a warm environment, air movement with elevated velocity is a well-known cooling strategy. The local air movement is typically generated by cooling fans (e.g., ceiling fan, table fans, etc.). Appearance, power input, and price are the main parameters considered today when purchasing cooling fans, while cooling capacity and efficiency of energy use are unknown. To address this knowledge gap, this paper introduces the cooling-fan efficiency (CFE) index, defined as the ratio between the cooling effect (measured with a thermal manikin) generated by the device and its power consumption. The index was determined for a ceiling fan, a desk fan, standing fan, and a tower fan in a real office at three room air temperatures and at different fan speed levels. The results reveal that the index is sensitive enough to identify differences in the performance of the cooling devices. A standard method for testing fan cooling effect and an index for determining fan efficiency, such as the CFE index proposed in this study, need to be developed. The cooling fans generate a nonuniform velocity field around occupants, which cannot be described with a single air-velociry value. Therefore, it is not clear how to apply in practice the recommended elevated velocities in warm environments presented in the present standards. The standards need to be revised.

  20. Variation of transmittance spectra of porous antireflection coatings with index profile

    International Nuclear Information System (INIS)

    Transmittance spectra were calculated for single-layer coatings with the homogeneous refractive index, index profiles that increase monotonically with distance into the coating, and index profiles that rise in discrete steps. The calculations predict that large transmittance at tuned wavelengths can be obtained using any of these coating designs and known, porous silica coating materials. The spectral bandwidth of transmittance maxima increases when the index profile is altered from homogeneous to any profile whose index increases monotonically with thickness in the coating. Bandwidth is greatest for the linear-ramp coating whose index rises linearly from that of air to that of the substrate

  1. Air refractive index measurement using low-coherence interferometry.

    Czech Academy of Sciences Publication Activity Database

    Pikálek, Tomáš; Buchta, Zden?k

    2015-01-01

    Ro?. 54, ?. 16 (2015), s. 5024-5020. ISSN 1559-128X R&D Projects: GA MŠk ED0017/01/01; GA MŠk(CZ) LO1212; GA ?R GB14-36681G Institutional support: RVO:68081731 Keywords : updated edlen equantion * frequency combs * laser * refractometry Subject RIV: BH - Optics, Masers, Laser s Impact factor: 1.784, year: 2014

  2. New share index to track progress of environmental industry

    International Nuclear Information System (INIS)

    This article discusses the work of the environmental finance house Imax Capital in persuading investors to invest in environmental industries. The development of the ET-50 Index by Impax Capital Asset Management to track progress of the environmental industry is reported, and the categories of the ET-50 including alternative energy generators and equipment providers, air and water pollution control, soil and site remediation, recycling and waste management, and environmental engineering and consulting are considered. The performance of the ET-50 Index, and the work of Impax and RER in the development of a dedicated renewable energy share index by are discussed

  3. Graded Index Microstructured Polymer Optical Fibers for Terahertz Applications

    OpenAIRE

    Ma, Tian; Markov, Andrey; Wang, Lili; Skorobogatiy, Maksim

    2014-01-01

    Graded index microstructured polymer optical fiber incorporating a specially designed air-hole array featuring variable air-hole diameters and inter-hole separation is proposed, fabricated and characterized in view of the fiber potential applications in low-loss, low-dispersion terahertz guidance. The proposed fiber features simultaneously low chromatic and intermodal dispersions, as well as low loss in the terahertz spectral range. We then experimentally demonstrate that pr...

  4. Large elliptical nanostructured gradient-index microlens.

    Science.gov (United States)

    Buczynski, Ryszard; Filipkowski, Adam; Waddie, Andrew J; Piechal, Bernard; Nowosielski, Jedrzej; Pysz, Dariusz; Stepien, Ryszard; Taghizadeh, Mohammad R

    2016-01-01

    We demonstrate the feasibility of the development of a gradient-index elliptical microlens with a size of 75×125???m using nanostructured glass technology. The gradient index is obtained by means of a discrete internal structure composed of two glasses with feature sizes much smaller than the wavelength of the incident light. A modified photonic crystal fiber-drawing technique is used for the lens fabrication. The elliptical shape of the lens is obtained by a novel final drawing stage where the spherically symmetric lens preform is drawn into an elliptical form by collapsing two large air holes placed in the preform during assembly. The effective focal lengths of 160 and 260 ?m for the orthogonal axes are obtained experimentally for the fabricated lens, and show good agreement with those predicted by the effective medium theory and the full-wave beam propagation simulations. PMID:26835626

  5. Negative refractive index metamaterials

    Directory of Open Access Journals (Sweden)

    Willie J. Padilla

    2006-07-01

    Full Text Available Engineered materials composed of designed inclusions can exhibit exotic and unique electromagnetic properties not inherent in the individual constituent components. These artificially structured composites, known as metamaterials, have the potential to fill critical voids in the electromagnetic spectrum where material response is limited and enable the construction of novel devices. Recently, metamaterials that display negative refractive index – a property not found in any known naturally occurring material – have drawn significant scientific interest, underscoring the remarkable potential of metamaterials to facilitate new developments in electromagnetism.

  6. BGS geoscience index system

    OpenAIRE

    Loudon, T. V.

    1992-01-01

    It is appropriate, at a amap library automation workshop on the British Geological Survey's home ground, to consider a new initiative that has a bearing on BGS's map indexing activities. The geological map is a primary means of communicating geological information, especially that collected by methodical geological survey. BGS has therefore been a publisher of maps since 1835, mostly at 1:50 000 and smaller scales. In addition,BGS staff are users of geological and other maps world-wide, and t...

  7. Software Maintainability Index Revisited

    Energy Technology Data Exchange (ETDEWEB)

    Welker, Kurt Dean

    2001-08-01

    For many years now, software practitioners have been collecting metrics from source code in an effort to better understand the software they are developing or changing. Maintainability Index (MI) is a composite metric that incorporates a number of traditional source code metrics into a single number that indicates relative maintainability. As originally proposed by Oman and Hagemeister, the MI is comprised of weighted Halstead metrics (effort or volume), McCabe's Cyclomatic Complexity, lines of code (LOC), and number of comments [1, 2]. Two equations were presented: one that considered comments and one that did not.

  8. Monitoring of Air Polution by Using Fuzzy Logic

    OpenAIRE

    Dr. Gopal Upadhyaya,; Mr. Nilesh Dashore

    2010-01-01

    The Air Quality Index is a simple and generalized way to describe the air quality in China, Hong Kong, Malaysia and now in India. Indian Air Quality Index (IND-AQI) is mainly a health related index with the descriptor words: “Good (0- 100)”, “Moderate (101-200 )”, “Poor (201-300)”, “Very Poor (301-400)”, “Severe (401-500)”. State Environment Protection Agency (SEPA ) is responsible for measuring the level of air pollution in China . In China the AQI is based on the level of 5 atmospheric poll...

  9. 2001 Environmental Sustainability Index (ESI)

    Data.gov (United States)

    National Aeronautics and Space Administration — The 2001 Environmental Sustainability Index (ESI) utilizes a refined methodology based on the 2000 Pilot ESI effort, to construct an index covering 122 countries...

  10. Liberalizing air cargo services in APEC

    OpenAIRE

    Geloso Grosso, Massimo; Shepherd, Ben

    2009-01-01

    This study aims at assessing the link between a more liberal air cargo regime and increased bilateral merchandise trade in the Asia Pacific region, under the auspices of APEC. Using the gravity model and employing the Air Liberalisation Index (ALI) developed by the WTO Secretariat, this paper finds strong support for two hypotheses. First, more liberal air services policies are positively, significantly and robustly associated with higher bilateral trade in merchandise. The results also sh...

  11. Visceral Adiposity Index

    Science.gov (United States)

    Amato, Marco C.; Giordano, Carla; Galia, Massimo; Criscimanna, Angela; Vitabile, Salvatore; Midiri, Massimo; Galluzzo, Aldo

    2010-01-01

    OBJECTIVE To individuate a novel sex-specific index, based on waist circumference, BMI, triglycerides, and HDL cholesterol, indirectly expressing visceral fat function. RESEARCH DESIGN AND METHODS Visceral adiposity index (VAI) was first modeled on 315 nonobese healthy subjects. Using two multiple logistic regression models, VAI was retrospectively validated in 1,498 primary care patients in comparison to classical cardio- and cerebrovascular risk factors. RESULTS All components of metabolic syndrome increased significantly across VAI quintiles. VAI was independently associated with both cardiovascular (odd ratio [OR] 2.45; 95% CI 1.52–3.95; P < 0.001) and cerebrovascular (1.63; 1.06–2.50; P = 0.025) events. VAI also showed significant inverse correlation with insulin sensitivity during euglycemic-hyperinsulinemic clamp in a subgroup of patients (Rs = ?0.721; P < 0.001). By contrast, no correlations were found for waist circumference and BMI. CONCLUSIONS Our study suggests VAI is a valuable indicator of “visceral adipose function” and insulin sensitivity, and its increase is strongly associated with cardiometabolic risk. PMID:20067971

  12. Growth Index after Planck

    CERN Document Server

    Xu, Lixin

    2013-01-01

    To investigate the possible deviation from the standard $\\Lambda$CDM model and the Einstein's gravity theory in the dynamical perspectives, the growth index $\\gamma_L$ was proposed. Recently, thanks to the measurement of the cosmic growth rate via the redshift-space distortion, one can understand the evolution of density contrast through $f\\sigma_8(z)$, where $f(z)=d\\ln \\delta/d \\ln a$ is the growth rate of matter and $\\sigma_8(z)$ is the rms amplitude of the density contrast $\\delta$ at the comoving $8h^{-1}$ Mpc scale. In this paper, we use the red-shift space distortion data points to investigate the growth index on the bases of the Einstein's gravity theory and a modified gravity theory under the assumption $f=\\Omega_m(a)^{\\gamma_L}$. To fix the background evolution, the cosmic observational data points from the type Ia supernovae SNLS3, cosmic microwave background radiation from {\\it Planck} and baryon acoustic oscillation are used. Via the Markov Chain Monte Carlo method, the $\\gamma_L$ values were obta...

  13. Lies, Damn Lies, and Indexes.

    Science.gov (United States)

    Lance, Keith Curry; Cox, Marti A.

    2000-01-01

    Offers a methodological critique of Thomas Hennen's American Public Library Rating Index as well as a response by Hennen. Discusses statistics; indexes; correlations; variables; weighting; and how public libraries should be assessed, and Hennen defends his work and suggests it should be called a scorecard rather than an index. (LRW)

  14. Air lock

    International Nuclear Information System (INIS)

    The patent refers to an air lock system preferably for nuclear stations for the transport of heavy loads by means of a trolley on rails. For opening and closing of the air lock parts of the rails are removed, e.g. by a second rail system perpendicular to the main rails. (P.K.)

  15. Designing of Index-Guiding Photonic Crystal Fibre by Finite Element Method Simulation

    Directory of Open Access Journals (Sweden)

    S. S. Mishra

    2010-11-01

    Full Text Available Different structures of Index-guiding Photonic crystal fibre are designed. The attractive vectorial Finite Element Method simulation technique is used to analyse such PCFs by taking suitable fibre parameter i.e. air hole diameter (d, pitch (? and air core diameter (d¥.Few important properties such as variation of refractive index with wavelength and nice confinement modal field pattern were studied. Index-guided photonic crystal fibre having inner core of radius 0.2µm, pitch 2.4µm and identical air hole of diameter d=1.38µm is suggested for which leakage of signal is almost zero at wavelength 1.55µm.

  16. Superbridge index of composite knots

    OpenAIRE

    Jin, Gyo Taek

    2000-01-01

    An upper bound of the superbridge index of the connected sum of two knots is given in terms of the braid index of the summands. Using this upper bound and minimal polygonal presentations, we give an upper bound in terms of the superbridge index and the bridge index of the summands when they are torus knots. In contrast to the fact that the difference between the sum of bridge indices of two knots and the bridge index of their connected sum is always one, the corresponding difference for the s...

  17. Automated Water Extraction Index

    DEFF Research Database (Denmark)

    Feyisa, Gudina Legese; Meilby, Henrik; Fensholt, Rasmus; Proud, Simon Richard

    2014-01-01

    Classifying surface cover types and analyzing changes are among the most common applications of remote sensing. One of the most basic classification tasks is to distinguish water bodies from dry land surfaces. Landsat imagery is among the most widely used sources of data in remote sensing of water...... resources; and although several techniques of surface water extraction using Landsat data are described in the literature, their application is constrained by low accuracy in various situations. Besides, with the use of techniques such as single band thresholding and two-band indices, identifying an...... appropriate threshold yielding the highest possible accuracy is a challenging and time consuming task, as threshold values vary with location and time of image acquisition. The purpose of this study was therefore to devise an index that consistently improves water extraction accuracy in the presence of...

  18. Indexing contamination surveys

    International Nuclear Information System (INIS)

    The responsibility for safely managing the Tank Farms at Hanford belongs to Lockheed Martin Hanford Corporation which is part of the six company Project Hanford Management Team led by Fluor Daniel Hanford, Inc.. These Tank Farm Facilities contain numerous outdoor contamination areas which are surveyed at a periodicity consistent with the potential radiological conditions, occupancy, and risk of changes in radiological conditions. This document describes the survey documentation and data tracking method devised to track the results of contamination surveys this process is referred to as indexing. The indexing process takes a representative data set as an indicator for the contamination status of the facility. The data are further manipulated into a single value that can be tracked and trended using standard statistical methodology. To report meaningful data, the routine contamination surveys must be performed in a manner that allows the survey method and the data collection process to be recreated. Three key criteria are necessary to accomplish this goal: Accurate maps, consistent documentation, and consistent consolidation of data meeting these criteria provides data of sufficient quality to be tracked. Tracking of survey data is accomplished by converting the individual survey results into a weighted value, corrected for the actual number of survey points. This information can be compared over time using standard statistical analysis to identify trends. At the Tank Farms, the need to track and trend the facility's radiological status presents unique challenges. Many of these Tank Farm facilities date back to the second world war. The Tank Farm Facilities are exposed to weather extremes, plant and animal intrusion, as well as all of the normal challenges associated with handling radiological waste streams. Routine radiological surveys did not provide a radiological status adequate for continuing comparisons

  19. Variación espacial de la exposición a contaminación atmosférica en la ciudad de Valencia y su relación con un índice de privación The spatial distribution of population exposure to outdoor air pollution in Valencia (Spain and its association with a privation index

    Directory of Open Access Journals (Sweden)

    Marisa Estarlich

    2013-04-01

    Full Text Available Objetivo: Evaluar la variación espacial de la exposición a dióxido de nitrógeno (NO2 en la ciudad de Valencia y su relación con la privación socioeconómica y la edad. Métodos: La población por sección censal (SC procede del Instituto Nacional de Estadística. Los niveles de NO2 se midieron en 100 puntos del área de estudio, mediante captadores pasivos, en tres campañas entre 2002 y 2004. Se utilizó regresión por usos del suelo (LUR para obtener el mapa de los niveles de NO2. Las predicciones del LUR se compararon con las proporcionadas por: a el captador más cercano de la red de vigilancia, b el captador pasivo más cercano, c el conjunto de captadores en un entorno y d kriging. Se asignaron niveles de contaminación para cada SC. Se analizó la relación entre los niveles de NO2, un índice de privación con cinco categorías y la edad (>65 años. Resultados: El modelo LUR resultó el método más preciso. Más del 99% de la población superó los niveles de seguridad propuestos por la Organización Mundial de la Salud. Se encontró una relación inversa entre los niveles de NO2 y el índice de privación (? = -2,01?g/m³ en el quintil de mayor privación respecto al de menor, IC95%: -3,07 a -0,95, y una relación directa con la edad (? = 0,12?g/m³ por incremento en unidad porcentual de población >65 años, IC95%: 0,08 a 0,16. Conclusiones: El método permitió obtener mapas de contaminación y describir la relación entre niveles de NO2 y características sociodemográficas.Objective: To evaluate spatial variation in exposure to nitrogen dioxide (NO2 air pollution in the city of Valencia, Spain, and its association with socioeconomic deprivation and age. Methods: Census tract population data were obtained from the National Statistics Institute of Spain. Outdoor NO2 was monitored in 100 sites in the study area, through the use of passive samplers, in three campaigns between 2002 and April 2004. Land use regression (LUR was used to obtain a map of NO2 levels. The LUR predictions were compared with the NO2 level obtained by: a the nearest sampler of the monitoring network, b the nearest passive sampler, c the mean distance-weighted levels of the samplers in the neighborhood, and d the NO2 level obtained by using Kriging. For each census tract, the NO2 levels were obtained. The association of NO2 air pollution exposure with population age (>65 years and the 5-category deprivation index was analyzed. Results: The LUR models showed less error than the other prediction methods. The safety levels proposed by the World Health Organization were exceeded in more than 99% of the population. An inverse relationship was found between NO2 levels and the deprivation index (? = -2.01?g/m³ in the most deprived quintile compared with lower deprivation, 95%CI: -3.07; -0.95 and a direct relationship was found with age (? = 0.12?g/m³ per unit increase in percentage of the population > 65 years, 95%CI: 0.08; 0.16. Conclusions: The method allowed pollution maps to be obtained and the association between NO2 levels and sociodemographic characteristics to be described.

  20. Variación espacial de la exposición a contaminación atmosférica en la ciudad de Valencia y su relación con un índice de privación / The spatial distribution of population exposure to outdoor air pollution in Valencia (Spain) and its association with a privation index

    Scientific Electronic Library Online (English)

    Marisa, Estarlich; Carmen, Iñiguez; Ana, Esplugues; Enrique, Mantilla; Òscar, Zurriaga; Andreu, Nolasco; Ferran, Ballester.

    2013-04-01

    Full Text Available Objetivo: Evaluar la variación espacial de la exposición a dióxido de nitrógeno (NO2) en la ciudad de Valencia y su relación con la privación socioeconómica y la edad. Métodos: La población por sección censal (SC) procede del Instituto Nacional de Estadística. Los niveles de NO2 se midieron en 100 p [...] untos del área de estudio, mediante captadores pasivos, en tres campañas entre 2002 y 2004. Se utilizó regresión por usos del suelo (LUR) para obtener el mapa de los niveles de NO2. Las predicciones del LUR se compararon con las proporcionadas por: a) el captador más cercano de la red de vigilancia, b) el captador pasivo más cercano, c) el conjunto de captadores en un entorno y d) kriging. Se asignaron niveles de contaminación para cada SC. Se analizó la relación entre los niveles de NO2, un índice de privación con cinco categorías y la edad (>65 años). Resultados: El modelo LUR resultó el método más preciso. Más del 99% de la población superó los niveles de seguridad propuestos por la Organización Mundial de la Salud. Se encontró una relación inversa entre los niveles de NO2 y el índice de privación (? = -2,01?g/m³ en el quintil de mayor privación respecto al de menor, IC95%: -3,07 a -0,95), y una relación directa con la edad (? = 0,12?g/m³ por incremento en unidad porcentual de población >65 años, IC95%: 0,08 a 0,16). Conclusiones: El método permitió obtener mapas de contaminación y describir la relación entre niveles de NO2 y características sociodemográficas. Abstract in english Objective: To evaluate spatial variation in exposure to nitrogen dioxide (NO2) air pollution in the city of Valencia, Spain, and its association with socioeconomic deprivation and age. Methods: Census tract population data were obtained from the National Statistics Institute of Spain. Outdoor NO2 wa [...] s monitored in 100 sites in the study area, through the use of passive samplers, in three campaigns between 2002 and April 2004. Land use regression (LUR) was used to obtain a map of NO2 levels. The LUR predictions were compared with the NO2 level obtained by: a) the nearest sampler of the monitoring network, b) the nearest passive sampler, c) the mean distance-weighted levels of the samplers in the neighborhood, and d) the NO2 level obtained by using Kriging. For each census tract, the NO2 levels were obtained. The association of NO2 air pollution exposure with population age (>65 years) and the 5-category deprivation index was analyzed. Results: The LUR models showed less error than the other prediction methods. The safety levels proposed by the World Health Organization were exceeded in more than 99% of the population. An inverse relationship was found between NO2 levels and the deprivation index (? = -2.01?g/m³ in the most deprived quintile compared with lower deprivation, 95%CI: -3.07; -0.95) and a direct relationship was found with age (? = 0.12?g/m³ per unit increase in percentage of the population > 65 years, 95%CI: 0.08; 0.16). Conclusions: The method allowed pollution maps to be obtained and the association between NO2 levels and sociodemographic characteristics to be described.

  1. Air filter

    International Nuclear Information System (INIS)

    An air filter consists of an upright cylinder of corrugated or pleated filter fabric, joined at its upper end to a tubular right-angled elbow. The open end of the elbow includes an internal lip seal, so the elbow can be slid onto a horizontal spigot in an air filter unit. The filter can be cleaned by subjecting the fabric to a reverse pressure pulse from a nozzle. The construction facilitates removal of the filter into a plastic bag secured round a frame behind a door, when the unit is used to filter radioactive dust from air. (author)

  2. Generalizations of Wiener polarity index and terminal Wiener index

    CERN Document Server

    Ilic, Aleksandar

    2011-01-01

    In theoretical chemistry, distance-based molecular structure descriptors are used for modeling physical, pharmacologic, biological and other properties of chemical compounds. We introduce a generalized Wiener polarity index $W_k (G)$ as the number of unordered pairs of vertices $\\{u, v\\}$ of $G$ such that the shortest distance $d (u, v)$ between $u$ and $v$ is $k$. For $k = 3$, we get standard Wiener polarity index. Furthermore, we generalize the terminal Wiener index $TW_k (G)$ as the sum of distances between all pairs of vertices of degree $k$. For $k = 1$, we get standard terminal Wiener index. In this paper we describe a linear time algorithm for computing these indices for trees and partial cubes, and characterize extremal trees maximizing the generalized Wiener polarity index and generalized terminal Wiener index among all trees of given order $n$.

  3. The glycemic index.

    Science.gov (United States)

    Wolever, T M

    1990-01-01

    Different starchy foods produce different glycemic responses when fed individually, and there is evidence that this also applies in the context of the mixed meal. Methods of processing, and other factors unrelated to the nutrient composition of foods may also have major effects on the glycemic response. The reason for differences in glycemic response appears to relate to the rate at which the foods are digested and the many factors influencing this. The glycemic index (GI) is a system of classification in which the glycemic responses of foods are indexed against a standard (white bread). This allows the results of different investigators to be pooled. GI values also depend upon a number of nonfood-related variables. The method of calculation of the glycemic response area is most important, but the method of blood sampling and length of time of studies also may have effects. Variability of glycemic responses arises from day-to-day variation in the same subject and variation between different subjects. There is less variability between the GI values of different subjects than there is within the same subject from day to day. Therefore, the mean GI values of foods are independent of the glucose tolerance status of the subjects being tested. Potentially clinically useful starchy foods producing relatively flat glycemic responses have been identified, including legumes, pasta, barley, bulgur, parboiled rice and whole grain breads such as pumpernickel. Specific incorporation of these foods into diets have been associated with reduced blood glucose, insulin, and lipid levels. Low-GI foods may influence amino acid metabolism although the implications of these are unknown. In addition, low GI foods increase colonic fermentation. The physiologic and metabolic implications of this relate to increased bacterial urea utilization, and to the production and absorption of short chain fatty acids in the colon. The application of the GI to therapeutic diets should be in the context of the overall nutrient composition of the diet. High-fat or high-sugar foods may have a low GI, but it may not be prudent to recommend these foods solely on the basis of the GI. It is therefore suggested that the most appropriate use of the GI is to rank the glycemic effects of starchy foods which would already have been chosen for possible inclusion in the diet on the basis of their nutritional attributes, i.e. low-fat, unrefined carbohydrate. PMID:2180214

  4. 2012 Environmental Performance Index and Pilot Trend Environmental Performance Index

    Data.gov (United States)

    National Aeronautics and Space Administration — The 2012 Environmental Performance Index (EPI) ranks 132 countries on 22 performance indicators in the following 10 policy categories: environmental burden of...

  5. 2012 Environmental Performance Index and Pilot Trend Environmental Performance Index

    Data.gov (United States)

    National Aeronautics and Space Administration — The 2012 Environmental Performance Index (EPI) ranks 132 countries on 22 performance indicators in the following 10 policy categories: environmental burden of...

  6. Dependence with air density of the response of the PTW SourceCheck ionization chamber for low energy brachytherapy sources

    Energy Technology Data Exchange (ETDEWEB)

    Tornero-López, Ana M.; Guirado, Damián; Ruiz-Arrebola, Samuel [Servicio de Radiofísica y Protección Radiológica, Hospital Universitario San Cecilio, E-18012 Granada (Spain); Perez-Calatayud, Jose [Servicio de Radioterapia, Unidad de Radiofísica, Hospital Universitario y Politécnico La Fe, E-46026 Valencia (Spain); Simancas, Fernando; Lallena, Antonio M. [Departamento de Física Atómica, Molecular y Nuclear, Universidad de Granada, E-18071 Granada (Spain); Gazdic-Santic, Maja [Department of Medical Physics and Radiation Safety, Clinical Centre of Sarajevo University, 71000 Sarajevo (Bosnia and Herzegovina)

    2013-12-15

    Purpose: Air-communicating well ionization chambers are commonly used to assess air kerma strength of sources used in brachytherapy. The signal produced is supposed to be proportional to the air density within the chamber and, therefore, a density-independent air kerma strength is obtained when the measurement is corrected to standard atmospheric conditions using the usual temperature and pressure correction factor. Nevertheless, when assessing low energy sources, the ionization chambers may not fulfill that condition and a residual density dependence still remains after correction. In this work, the authors examined the behavior of the PTW 34051 SourceCheck ionization chamber when measuring the air kerma strength of {sup 125}I seeds.Methods: Four different SourceCheck chambers were analyzed. With each one of them, two series of measurements of the air kerma strength for {sup 125}I selectSeed{sup TM} brachytherapy sources were performed inside a pressure chamber and varying the pressure in a range from 747 to 1040 hPa (560 to 780 mm Hg). The temperature and relative humidity were kept basically constant. An analogous experiment was performed by taking measurements at different altitudes above sea level.Results: Contrary to other well-known ionization chambers, like the HDR1000 PLUS, in which the temperature-pressure correction factor overcorrects the measurements, in the SourceCheck ionization chamber they are undercorrected. At a typical atmospheric situation of 933 hPa (700 mm Hg) and 20 °C, this undercorrection turns out to be 1.5%. Corrected measurements show a residual linear dependence on the density and, as a consequence, an additional density dependent correction must be applied. The slope of this residual linear density dependence is different for each SourceCheck chamber investigated. The results obtained by taking measurements at different altitudes are compatible with those obtained with the pressure chamber.Conclusions: Variations of the altitude and changes in the weather conditions may produce significant density corrections, and that effect should be taken into account. This effect is chamber-dependent, indicating that a specific calibration is necessary for each particular chamber. To our knowledge, this correction has not been considered so far for SourceCheck ionization chambers, but its magnitude cannot be neglected in clinical practice. The atmospheric pressure and temperature at which the chamber was calibrated need to be taken into account, and they should be reported in the calibration certificate. In addition, each institution should analyze the particular response of its SourceCheck ionization chamber and compute the adequate correction factors. In the absence of a suitable pressure chamber, a possibility for this assessment is to take measurements at different altitudes, spanning a wide enough air density range.

  7. Applied Parallel Metadata Indexing

    Energy Technology Data Exchange (ETDEWEB)

    Jacobi, Michael R [Los Alamos National Laboratory

    2012-08-01

    The GPFS Archive is parallel archive is a parallel archive used by hundreds of users in the Turquoise collaboration network. It houses 4+ petabytes of data in more than 170 million files. Currently, users must navigate the file system to retrieve their data, requiring them to remember file paths and names. A better solution might allow users to tag data with meaningful labels and searach the archive using standard and user-defined metadata, while maintaining security. last summer, I developed the backend to a tool that adheres to these design goals. The backend works by importing GPFS metadata into a MongoDB cluster, which is then indexed on each attribute. This summer, the author implemented security and developed the user interfae for the search tool. To meet security requirements, each database table is associated with a single user, which only stores records that the user may read, and requires a set of credentials to access. The interface to the search tool is implemented using FUSE (Filesystem in USErspace). FUSE is an intermediate layer that intercepts file system calls and allows the developer to redefine how those calls behave. In the case of this tool, FUSE interfaces with MongoDB to issue queries and populate output. A FUSE implementation is desirable because it allows users to interact with the search tool using commands they are already familiar with. These security and interface additions are essential for a usable product.

  8. A New Comparison of the "Current Index to Journals in Education" and the "Education Index": A Deep Analysis of Indexing.

    Science.gov (United States)

    Brown, M. Suzanne; Edwards, Jana S.; LaSee-Willemssen, Jeneen

    1999-01-01

    This article compares "Current Index to Journals in Education" (CIJE) with "Education Index" by article type and reveals pronounced differences in indexing practices. Implications for educational and interdisciplinary research, reference services, index selection, and library instruction are discussed. (Author)

  9. Recommended concentration limits of indoor air pollution indicators for requirement of acceptable indoor air quality

    Directory of Open Access Journals (Sweden)

    Wang J., Zhang X.

    2010-07-01

    Full Text Available Object and goals of indoor air pollution control with ventilation may influence improvement of indoor air quality, building energy consumption and even carbon emissions. Indicators of indoor air pollution caused by occupants-related sources and building-related sources were chosen based on sources emitting characteristics, pollutants composition, indicator choosing principles and indoor air pollution situation in China. Then the recommended concentration limits of indicators were given for unadapted and adapted persons according to logarithmic index evaluation method, combined with percentage of dissatisfaction and joint effect of indoor air pollution caused by these two kinds of sources.

  10. Aeronautical Engineering: 1983 cumulative index

    Science.gov (United States)

    1984-01-01

    This bibliography is a cumulative index to the abstracts contained in NASA SP-7037 (158) through NASA SP-7037 (169) of Aeronautical Engineering: A Continuing Bibliography. NASA SP-7037 and its supplements have been compiled through the cooperative efforts of the American Institute of Aeronautics and Astronautics (AIAA) and the National Aeronautics and Space Administration (NASA). This cumulative index includes subject, personal author, corporate source, contract, report number, and accession number indexes.

  11. Equiseparability on Terminal Wiener Index

    DEFF Research Database (Denmark)

    Deng, Xiaotie; Zhang, Jie

    2012-01-01

    The aim of this work is to explore the properties of the terminal Wiener index, which was recently proposed by Gutman et al. (2004) [3], and to show the fact that there exist pairs of trees and chemical trees which cannot be distinguished by using it. We give some general methods for constructing equiseparable pairs and compare the methods with the case for the Wiener index. More specifically, we show that the terminal Wiener index is degenerate to some extent.

  12. Filter indexing for spectrophotometer system

    International Nuclear Information System (INIS)

    A spectrophotometer system has an optical system for transmitting a beam from a source at select wavelengths onto a detector. A plurality of filters are positioned in a tray. A stepper mechanism indexes the tray along a path. A microcomputer controls the stepper mechanism and the optical system. The wavelength is successively changed over a range, the tray is indexed to move a select filter into the beam at a predetermined wavelength and the changing is discontinued during indexing

  13. 2008 Environmental Performance Index (EPI)

    Data.gov (United States)

    National Aeronautics and Space Administration — The 2008 Environmental Performance Index (EPI) centers on two broad environmental protection objectives: (1) reducing environmental stresses on human health, and...

  14. 2008 Environmental Performance Index (EPI)

    Data.gov (United States)

    National Aeronautics and Space Administration — The 2008 Environmental Performance Index (EPI) centers on two broad environmental protection objectives: (1) reducing environmental stresses on human health, and...

  15. 2010 Environmental Performance Index (EPI)

    Data.gov (United States)

    National Aeronautics and Space Administration — The 2010 Environmental Performance Index (EPI) ranks 163 countries on environmental performance based on twenty-five indicators grouped within ten core policy...

  16. Topological Dynamics indexed by words

    CERN Document Server

    Farmaki, Vassiliki

    2011-01-01

    Starting with a combinatorial partition theorem for words over an infinite alphabet dominated by a fixed sequence, established recently by the authors, we prove recurrence results for topological dynamical systems indexed by such words. In this way we extend the classical theory developed by Furstenberg and Weiss of dynamical systems indexed by the natural numbers to systems indexed by words. Moreover, applying this theory to topological systems indexed by semigroups that can be represented as words we get analogous recurrence results for such systems.

  17. 2002 Environmental Sustainability Index (ESI)

    Data.gov (United States)

    National Aeronautics and Space Administration — The 2002 Environmental Sustainability Index (ESI) measures overall progress toward environmental sustainability for 142 countries based on environmental systems,...

  18. 2002 Environmental Sustainability Index (ESI)

    Data.gov (United States)

    National Aeronautics and Space Administration — The 2002 Environmental Sustainability Index (ESI) measures overall progress toward environmental sustainability for 142 countries based on environmental systems,...

  19. Computer aided indexing at NASA

    Science.gov (United States)

    Buchan, Ronald L.

    1987-01-01

    The application of computer technology to the construction of the NASA Thesaurus and in NASA Lexical Dictionary development is discussed in a brief overview. Consideration is given to the printed and online versions of the Thesaurus, retrospective indexing, the NASA RECON frequency command, demand indexing, lists of terms by category, and the STAR and IAA annual subject indexes. The evolution of computer methods in the Lexical Dictionary program is traced, from DOD and DOE subject switching to LCSH machine-aided indexing and current techniques for handling natural language (e.g., the elimination of verbs to facilitate breakdown of sentences into words and phrases).

  20. VARIABILITY OF THE THERMAL CONTINENTALITY INDEX IN CENTRAL EUROPE

    Directory of Open Access Journals (Sweden)

    CIARANEK1 DOMINIKA

    2014-03-01

    Full Text Available The paper presents the spatial and temporal variability of thermal continentality in Central Europe. Gorczy?ski’s and Johansson-Ringleb’s formulae were used to derive the continentality index. The study also looked at the annual patterns of air temperature amplitude (A, a component of both of these formulae, and D; the difference between the average temperatures of autumn (Sep.-Nov. and spring (Mar.-May. Records of six weather stations representing the climate of Central Europe were included in the study covering the period 1775-2012 (Potsdam, Drezden, Prague, Vienna, Krakow, Debrecen. The highest continentality index was found in Debrecen and the lowest in Potsdam. The continentality index fluctuated with time with two pronounced dips at the turn of the 19th century and in the second half of the 20th century. The highest continentality index values were recorded during the 1930s and 1940s.