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1

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)

2

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)

3

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)

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)

Andrade, Marcos Ely Almeida

2008-07-01

4

New LNHB primary standard for 60Co air kerma  

International Nuclear Information System (INIS)

As a single working chamber for a national air kerma standard was not considered safe and robust enough, a new set of six ionization chambers was devised to establish the French 60Co air kerma standard. 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 (example: mean energy expended by an electron to produce an ion pair in dry air), while others vary for each chamber (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 products of the six chamber-dependent factors was taken equal to the standard deviation of the sample composed of the products of the six chamber-dependent factors (0.078%). Compared with 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% ma rate uncertainty would drop from 0.38% to 0.31%. (authors)

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)

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

Energy Technology Data Exchange (ETDEWEB)

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)

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

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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

Angular dependence of the wall correction factor for air kerma measurements using cylindrical cavity chambers  

International Nuclear Information System (INIS)

The dependence of the results of air kerma measurements on the orientation of the cylindrical cavity chamber used for beam standardizations is reexamined. The wall attenuation correction factors for the 60Co and 136Cs air kerma measurements were obtained for various irradiation angles by extrapolation of the dependences of experimental data and by Monte Carlo simulations. Applying the correction based on extrapolation does not provide an angle-invariant air kerma rate, as desired. In contrast, Monte Carlo simulations, which take into account various affecting phenomena, produce a wall correction factor that makes the corrected air kerma independent of the incidence angle

11

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

12

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)

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)

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

13

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)

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The IPEM code of practice for determination of the reference air kerma rate for HDR (192)Ir brachytherapy sources based on the NPL air kerma standard.  

Science.gov (United States)

This paper contains the recommendations of the high dose rate (HDR) brachytherapy working party of the UK Institute of Physics and Engineering in Medicine (IPEM). The recommendations consist of a Code of Practice (COP) for the UK for measuring the reference air kerma rate (RAKR) of HDR (192)Ir brachytherapy sources. In 2004, the National Physical Laboratory (NPL) commissioned a primary standard for the realization of RAKR of HDR (192)Ir brachytherapy sources. This has meant that it is now possible to calibrate ionization chambers directly traceable to an air kerma standard using an (192)Ir source (Sander and Nutbrown 2006 NPL Report DQL-RD 004 (Teddington: NPL) http://publications.npl.co.uk). In order to use the source specification in terms of either RAKR, ?(R) (ICRU 1985 ICRU Report No 38 (Washington, DC: ICRU); ICRU 1997 ICRU Report No 58 (Bethesda, MD: ICRU)), or air kerma strength, S(K) (Nath et al 1995 Med. Phys. 22 209-34), it has been necessary to develop algorithms that can calculate the dose at any point around brachytherapy sources within the patient tissues. The AAPM TG-43 protocol (Nath et al 1995 Med. Phys. 22 209-34) and the 2004 update TG-43U1 (Rivard et al 2004 Med. Phys. 31 633-74) have been developed more fully than any other protocol and are widely used in commercial treatment planning systems. Since the TG-43 formalism uses the quantity air kerma strength, whereas this COP uses RAKR, a unit conversion from RAKR to air kerma strength was included in the appendix to this COP. It is recommended that the measured RAKR determined with a calibrated well chamber traceable to the NPL (192)Ir primary standard is used in the treatment planning system. The measurement uncertainty in the source calibration based on the system described in this COP has been reduced considerably compared to other methods based on interpolation techniques. PMID:20479510

Bidmead, A M; Sander, T; Locks, S M; Lee, C D; Aird, E G A; Nutbrown, R F; Flynn, A

2010-06-01

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The IPEM code of practice for determination of the reference air kerma rate for HDR {sup 192}Ir brachytherapy sources based on the NPL air kerma standard  

Energy Technology Data Exchange (ETDEWEB)

This paper contains the recommendations of the high dose rate (HDR) brachytherapy working party of the UK Institute of Physics and Engineering in Medicine (IPEM). The recommendations consist of a Code of Practice (COP) for the UK for measuring the reference air kerma rate (RAKR) of HDR {sup 192}Ir brachytherapy sources. In 2004, the National Physical Laboratory (NPL) commissioned a primary standard for the realization of RAKR of HDR {sup 192}Ir brachytherapy sources. This has meant that it is now possible to calibrate ionization chambers directly traceable to an air kerma standard using an {sup 192}Ir source (Sander and Nutbrown 2006 NPL Report DQL-RD 004 (Teddington: NPL) http://publications.npl.co.uk). In order to use the source specification in terms of either RAKR, .K{sub R} (ICRU 1985 ICRU Report No 38 (Washington, DC: ICRU); ICRU 1997 ICRU Report No 58 (Bethesda, MD: ICRU)), or air kerma strength, S{sub K} (Nath et al 1995 Med. Phys. 22 209-34), it has been necessary to develop algorithms that can calculate the dose at any point around brachytherapy sources within the patient tissues. The AAPM TG-43 protocol (Nath et al 1995 Med. Phys. 22 209-34) and the 2004 update TG-43U1 (Rivard et al 2004 Med. Phys. 31 633-74) have been developed more fully than any other protocol and are widely used in commercial treatment planning systems. Since the TG-43 formalism uses the quantity air kerma strength, whereas this COP uses RAKR, a unit conversion from RAKR to air kerma strength was included in the appendix to this COP. It is recommended that the measured RAKR determined with a calibrated well chamber traceable to the NPL {sup 192}Ir primary standard is used in the treatment planning system. The measurement uncertainty in the source calibration based on the system described in this COP has been reduced considerably compared to other methods based on interpolation techniques.

Bidmead, A M [Medical Physics, Royal Marsden Hospital, Fulham Road, London SW3 6JJ (United Kingdom); Sander, T; Nutbrown, R F [Acoustics and Ionising Radiation, National Physical Laboratory, Hampton Road, Teddington, Middlesex, TW11 0LW (United Kingdom); Locks, S M [Regional Medical Physics Department, NCCC block, Freeman Hospital, Newcastle upon Tyne, NE7 7DN (United Kingdom); Lee, C D [Medical Physics Department, Clatterbridge Centre for Oncology, Clatterbridge Road, Bebington, Wirral, Merseyside, CH63 4JY (United Kingdom); Aird, E G A [Medical Physics Department, Mt Vernon Hospital, Rickmansworth Road, Northwood, HA6 2RN (United Kingdom); Flynn, A, E-mail: Margaret.Bidmead@rmh.nhs.u [Medical Physics, Cookridge Hospital, Hospital Lane, Cookridge, Leeds, LS16 6QB (United Kingdom)

2010-06-07

16

The IPEM code of practice for determination of the reference air kerma rate for HDR 192Ir brachytherapy sources based on the NPL air kerma standard  

International Nuclear Information System (INIS)

This paper contains the recommendations of the high dose rate (HDR) brachytherapy working party of the UK Institute of Physics and Engineering in Medicine (IPEM). The recommendations consist of a Code of Practice (COP) for the UK for measuring the reference air kerma rate (RAKR) of HDR 192Ir brachytherapy sources. In 2004, the National Physical Laboratory (NPL) commissioned a primary standard for the realization of RAKR of HDR 192Ir brachytherapy sources. This has meant that it is now possible to calibrate ionization chambers directly traceable to an air kerma standard using an 192Ir source (Sander and Nutbrown 2006 NPL Report DQL-RD 004 (Teddington: NPL) http://publications.npl.co.uk). In order to use the source specification in terms of either RAKR, .KR (ICRU 1985 ICRU Report No 38 (Washington, DC: ICRU); ICRU 1997 ICRU Report No 58 (Bethesda, MD: ICRU)), or air kerma strength, SK (Nath et al 1995 Med. Phys. 22 209-34), it has been necessary to develop algorithms that can calculate the dose at any point around brachytherapy sources within the patient tissues. The AAPM TG-43 protocol (Nath et al 1995 Med. Phys. 22 209-34) and the 2004 update TG-43U1 (Rivard et al 2004 Med. Phys. 31 633-74) have been developed more fully than any other protocol and are widely used in commercial treatment planning systems. Since the TG-43 formalism uses the quantity air kerma strength, whereas this COP uses RAKR, a unit conversion eas this COP uses RAKR, a unit conversion from RAKR to air kerma strength was included in the appendix to this COP. It is recommended that the measured RAKR determined with a calibrated well chamber traceable to the NPL 192Ir primary standard is used in the treatment planning system. The measurement uncertainty in the source calibration based on the system described in this COP has been reduced considerably compared to other methods based on interpolation techniques.

17

The IPEM code of practice for determination of the reference air kerma rate for HDR 192Ir brachytherapy sources based on the NPL air kerma standard  

Science.gov (United States)

This paper contains the recommendations of the high dose rate (HDR) brachytherapy working party of the UK Institute of Physics and Engineering in Medicine (IPEM). The recommendations consist of a Code of Practice (COP) for the UK for measuring the reference air kerma rate (RAKR) of HDR 192Ir brachytherapy sources. In 2004, the National Physical Laboratory (NPL) commissioned a primary standard for the realization of RAKR of HDR 192Ir brachytherapy sources. This has meant that it is now possible to calibrate ionization chambers directly traceable to an air kerma standard using an 192Ir source (Sander and Nutbrown 2006 NPL Report DQL-RD 004 (Teddington: NPL) http://publications.npl.co.uk). In order to use the source specification in terms of either RAKR, \\dot K_R (ICRU 1985 ICRU Report No 38 (Washington, DC: ICRU); ICRU 1997 ICRU Report No 58 (Bethesda, MD: ICRU)), or air kerma strength, SK (Nath et al 1995 Med. Phys. 22 209-34), it has been necessary to develop algorithms that can calculate the dose at any point around brachytherapy sources within the patient tissues. The AAPM TG-43 protocol (Nath et al 1995 Med. Phys. 22 209-34) and the 2004 update TG-43U1 (Rivard et al 2004 Med. Phys. 31 633-74) have been developed more fully than any other protocol and are widely used in commercial treatment planning systems. Since the TG-43 formalism uses the quantity air kerma strength, whereas this COP uses RAKR, a unit conversion from RAKR to air kerma strength was included in the appendix to this COP. It is recommended that the measured RAKR determined with a calibrated well chamber traceable to the NPL 192Ir primary standard is used in the treatment planning system. The measurement uncertainty in the source calibration based on the system described in this COP has been reduced considerably compared to other methods based on interpolation techniques.

Bidmead, A. M.; Sander, T.; Locks, S. M.; Lee, C. D.; Aird, E. G. A.; Nutbrown, R. F.; Flynn, A.

2010-06-01

18

Reference air kerma and kerma-area product as estimators of peak skin dose for fluoroscopically guided interventions  

International Nuclear Information System (INIS)

Purpose: To determine more accurate regression formulas for estimating peak skin dose (PSD) from reference air kerma (RAK) or kerma-area product (KAP). Methods: After grouping of the data from 21 procedures into 13 clinically similar groups, assessments were made of optimal clustering using the Bayesian information criterion to obtain the optimal linear regressions of (log-transformed) PSD vs RAK, PSD vs KAP, and PSD vs RAK and KAP. Results: Three clusters of clinical groups were optimal in regression of PSD vs RAK, seven clusters of clinical groups were optimal in regression of PSD vs KAP, and six clusters of clinical groups were optimal in regression of PSD vs RAK and KAP. Prediction of PSD using both RAK and KAP is significantly better than prediction of PSD with either RAK or KAP alone. The regression of PSD vs RAK provided better predictions of PSD than the regression of PSD vs KAP. The partial-pooling (clustered) method yields smaller mean squared errors compared with the complete-pooling method.Conclusion: PSD distributions for interventional radiology procedures are log-normal. Estimates of PSD derived from RAK and KAP jointly are most accurate, followed closely by estimates derived from RAK alone. Estimates of PSD derived from KAP alone are the least accurate. Using a stochastic search approach, it is possible to cluster together certain dissimilar types of procedures to minimize the total error sum of squares.

19

Air kerma rate estimation by means of in-situ gamma spectrometry: A Bayesian approach  

International Nuclear Information System (INIS)

Full text: Bayesian inference is used to determine the Air Kerma Rate based on a set of in situ environmental gamma spectra measurements performed with a NaI(Tl) scintillation detector. A natural advantage of such approach is the possibility to quantify uncertainty not only in the Air Kerma Rate estimation but also for the gamma spectra which is unfolded within the procedure. The measurements were performed using a 3'' x 3'' NaI(Tl) scintillation detector. The response matrices of such detection system were calculated using a Monte Carlo code. For the calculations of the spectra as well as the Air Kerma Rate the WinBugs program was used. WinBugs is a dedicated software for Bayesian inference using Monte Carlo Markov chain methods (MCMC). The results of such calculations are shown and compared with other non-Bayesian approachs such as the Scofield-Gold iterative method and the Maximum Entropy Method

20

Air kerma intercomparison at sup 60 Co by solid TL detectors  

Energy Technology Data Exchange (ETDEWEB)

Air kerma produced by {sup 60}Co gamma radiation from two laboratories were compared by irradiating dosemeters on the same day in Sao Paulo and in Helsinki. The thermoluminescent fading of the posted dosemeters was controlled by performing irradiations in the same laboratory 13 days before and 10 days after the irradiation of the reference group. The ratio of the air kerma values as determined from the irradiations in the two laboratories was 0.971 +- 0.016, at the 95% confidence level. The uncertainty caused by fading was shown to be negligible. The difference of about 3% in the air kerma values was thus clearly demonstrated by the TLD method. Systematic and random errors in TLD with solid detectors are discussed together with methods for their minimisation. (author).

Toivonen, M.; Jaervinen, H. (Finnish Centre for Radiation and Nuclear Safety (STUK), Helsinki (Finland)); Campos, L.; Las, W. (Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil))

1990-01-01

21

Air Kerma Rate estimation by means of in-situ gamma spectrometry: A Bayesian approach  

Energy Technology Data Exchange (ETDEWEB)

Bayesian inference is used to determine the Air Kerma Rate based on in-situ gamma spectrum measurement performed with an NaI(Tl) scintillation detector. The procedure accounts for uncertainties in the measurement and in the mass energy transfer coefficients needed for the calculation. The WinBUGS program () was used. The results show that the relative uncertainties in the Air Kerma estimate are of about 1%, and that the choice of unfolding procedure may lead to an estimate systematic error of 3%.

Cabal, Gonzalo [Department of Dosimetry and Applications of Ionizing Radiation, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Brehova 7, 115 19 Prague 1 (Czech Republic); Department of Radiation Dosimetry, Nuclear Physics Institute, Academy of Sciences of the Czech Republic, Na Truhlarce 39/64, 180 86 Prague 8 (Czech Republic)], E-mail: cabal@ujf.cas.cz; Kluson, Jaroslav [Department of Dosimetry and Applications of Ionizing Radiation, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Brehova 7, 115 19 Prague 1 (Czech Republic)

2010-04-15

22

Air Kerma Rate estimation by means of in-situ gamma spectrometry: A Bayesian approach  

International Nuclear Information System (INIS)

Bayesian inference is used to determine the Air Kerma Rate based on in-situ gamma spectrum measurement performed with an NaI(Tl) scintillation detector. The procedure accounts for uncertainties in the measurement and in the mass energy transfer coefficients needed for the calculation. The WinBUGS program () was used. The results show that the relative uncertainties in the Air Kerma estimate are of about 1%, and that the choice of unfolding procedure may lead to an estimate systematic error of 3%.

23

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)

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)

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

24

Energy-absorption buildup factors, effective atomic numbers and air-kerma for human body parts, vitamins and tissue substitutes  

International Nuclear Information System (INIS)

Effective atomic numbers Zeff, air-kerma and energy-absorption buildup factors, EABF for some human organs and tissues, vitamins and tissue substitutes have been computed in the present work. Geometric-Progression (G-P) fitting method was applied for computation of EABF. It is observed that the EABF and air-kerma are dependent upon Zeff and chemical compositions. The EABF, Zeff and air-kerma of calcium carbonate and lithium carbonate are found in good agreement with cortical bone and fat, respectively. The EABF in the present work could be useful in medical diagnostics, radiation therapy procedures and also personal monitoring. (author)

25

Spectrally average conversion coefficients for air kerma to ambient dose equivalent for clinical linear accelerator  

International Nuclear Information System (INIS)

This work aims to calculate the conversion coefficients from air kerma to ambient dose equivalent, H*(10)/Kair for photon beams produced by linear accelerators, such as the Clinac-4, Clinac-6, Clinac-18 and Clinac-2500, after transmission through primary barriers of radiotherapy treatment rooms. Concrete walls of thickness 1.0, 1.5 and 2.0 m were irradiated with 30 cmx30 cm primary beam spectra. The transmitted spectra were calculated to obtain the conversion coefficients for beams found in radiotherapy services. The calculations were done using the MCNP-4B Monte Carlo code. The results indicate the need to use a factor of about 1.20 to obtain the ambient dose equivalent for radiation surveys near primary barriers using instruments calibrated in air kerma

26

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)

27

Air kerma distribution in an irradiation facility - Comparison of Monte Carlo simulations with physical dosimetry  

International Nuclear Information System (INIS)

In order to evaluate the effectiveness of Monte Carlo methods applied to shielding calculations, an air kerma rate evaluation was performed in different locations of a 60Co gamma irradiator, operated for industrial and research purposes in a state laboratory at Nuclear and Technological Inst. near Lisbon. The MCNPX code was used to perform the radiation transport simulation along the facility. Variance reduction techniques were used by implementing, among others, the weight window generator to account for the air kerma rate in the access maze leading to the facility's irradiation chamber. Analog Monte Carlo simulations were also performed to test the correct implementation of the non analog techniques used and to evaluate the computational efficiency gain. The validation of the computational results is discussed by comparison with physical dosimetry measurements using ionization chambers. The results obtained show a good agreement between the simulations and the measurements for the positions in and the exit of the irradiation room. Discrepancies were found for the positions where the air kerma rate is lower resulting from the deeper penetration of radiation across the shields and scattering through the maze walls. Further insight must be gained to improve the results at these positions. (authors)

28

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.

29

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

Science.gov (United States)

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.

Burns, D. T.; Kessler, C.

2009-05-01

30

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 unifor 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)

31

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

CERN Document Server

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...

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

2002-01-01

32

Effect of pressure, temperature and humidity in air on photon fluence and air kerma values at low photon energies  

International Nuclear Information System (INIS)

An investigation into the effect of pressure, temperature and humidity in air on photon fluence at a typical mammography, low bremsstrahlung energy (25 kVp), has been carried out. Pressure values corrected for humidity at varying temperatures were employed to determine the density of moist air. Using the corrected moist air densities, the X-ray photon fluence remaining after air attenuation has been computed assuming an X-ray focal spot-detector distance of 65 cm. Bremsstrahlung spectral distributions and the effects of pressure, temperature and humidity on the photon fluence from molybdenum and tungsten targets are illustrated. Comparative results suggest that such effects could be significant and need to be considered when calculating exposure levels from low-energy photons. The investigation showed that air kerma values from an X-ray spectrum that has significant lower-energy components is likely to be more sensitive to changes in pressure, temperature and humidity than the air kerma from an X-ray spectrum with lower-energy components less pronounced. Non-negligible air kerma values are involved

33

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese 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.

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

2004-12-01

34

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

Science.gov (United States)

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.

Davis, Stephen D.

35

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

36

Correlation of radioactivity measurements, air kerma rates and geological features of Sicily  

International Nuclear Information System (INIS)

Sicily, the largest Mediterranean island (with an extension of about 25000km2), exhibits a very wide variety of lithologies, ranging from sedimentary to metamorphic and volcanic rocks. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) have been applied to air kerma values measured by thermoluminescent dosimetry in several sites and to data of radionuclide concentrations, geochemical and mineralogical features of rocks and soils sampled in 29 sites of Sicily to point out similarities among different lithologies. The study was devoted to find multiple correlations and allow a better classification of Sicilian lithotypes. Samples of rocks and soils have been analyzed by X-ray fluorescence (XRF), X-ray diffractometry (XRD), and gamma-ray spectrometry. Major element concentrations, mineralogical data, along with specific activities of 40K, 238U, and 232Th natural radionuclides, have been determined in several samples. Geochemical, mineralogical and petrographic features are in good agreement with radiometric data. A survey was also performed to measure air kerma in outdoor environment using thermoluminescent dosimeters. The measured values were compared with the predicted levels computed from the radioisotope concentrations present in rock and soil samples. Moreover, collected data can be used to evaluate the health impact of the natural radioactivity on the populationation

37

Air kerma strength calibration of 0.6 cc Farmer chamber for 192Ir HDR source  

International Nuclear Information System (INIS)

One of the methods adopted by hospitals for the calibration of the HDR 192Ir source, in terms of Air Kerma Strength (AKS) is to use 0.6cc chamber at short source to chamber distances for measuring the air kerma rate at the chamber position and then compute the AKS using the appropriate correction factors. However, the 0.6 cc Farmer type chambers purchased by the users for the calibration of the HDR 192Ir source, are not generally provided with an HDR 192Ir calibration factor. With the result, many hospitals that have purchased the Farmer type chamber for the calibration of 192Ir HDR sources, use the 60Co calibration factor for this purpose. The use of 60Co calibration factor for the 192Ir HDR source would unnecessarily increase the uncertainty of the measured AKS. Again, because of the low chamber sensitivity, hospitals often use, source to chamber distances as small as a few cm for calibrating the 192Ir HDR source. In the absence of a rigid source-chamber positioning system, this can lead to several percent errors in AKS determination. Also, hospitals often don't take into account corrections for the room scatter or the fluence non-uniformity across the chamber, which further increase the uncertainty of the measured AKS

38

Air-kerma evaluation at the maze entrance of HDR brachytherapy facilities.  

Science.gov (United States)

In the absence of procedures for evaluating the design of brachytherapy (BT) facilities for radiation protection purposes, the methodology used for external beam radiotherapy facilities is often adapted. The purpose of this study is to adapt the NCRP 151 methodology for estimating the air-kerma rate at the door in BT facilities. Such methodology was checked against Monte Carlo (MC) techniques using the code Geant4. Five different facility designs were studied for (192)Ir and (60)Co HDR applications to account for several different bunker layouts.For the estimation of the lead thickness needed at the door, the use of transmission data for the real spectra at the door instead of the ones emitted by (192)Ir and (60)Co will reduce the lead thickness by a factor of five for (192)Ir and ten for (60)Co. This will significantly lighten the door and hence simplify construction and operating requirements for all bunkers.The adaptation proposed in this study to estimate the air-kerma rate at the door depends on the complexity of the maze: it provides good results for bunkers with a maze (i.e. similar to those used for linacs for which the NCRP 151 methodology was developed) but fails for less conventional designs. For those facilities, a specific Monte Carlo study is in order for reasons of safety and cost-effectiveness. PMID:25222942

Pujades, M C; Granero, D; Vijande, J; Ballester, F; Perez-Calatayud, J; Papagiannis, P; Siebert, F A

2014-12-01

39

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

40

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%

41

Comparison of the standards for air kerma of the NIST and the BIPM for 60Co gamma radiation  

International Nuclear Information System (INIS)

An indirect comparison of the standards for air kerma of the National Institute of Standards and Technology (NIST), USA, and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 60Co radiation beam of the BIPM in September 2011. The comparison result, based on the calibration coefficients for two transfer standards and expressed as a ratio of the NIST and the BIPM standards for air kerma, is 1.0039 with a combined standard uncertainty of 0.0034. The results are analysed and presented in terms of degrees of equivalence for entry in the BIPM key comparison database. (authors)

42

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)

43

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)

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.

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

44

Theoretical and experimental studies of the influence of air kerma rate on threshold contrast in diagnostic fluoroscopy systems.  

Science.gov (United States)

Experimental measurements of threshold contrast (CT) as a function of air kerma rate at the input plane of the image intensifier have been made for several diagnostic fluoroscopy units in clinical use. Threshold contrasts are determined by viewing a test object containing holes of fixed diameter and various depths under defined irradiation conditions. Kerma rate variations are effected by introducing aluminum sheets into the x-ray beam at fixed values of tube potential and current. At low kerma rates where quantum noise dominates, low tube potentials (60 kVp) usually yield lower values of CT than do higher potentials (100 kVp). At higher kerma rates the opposite is often true. A simple theoretical model for noise propagation in fluoroscopic imaging systems using models of diagnostic x-ray spectra lends qualitative support to the experimental findings. The often-quoted suggested upper limit of 100 mu R s-1 (0.87 mu Gy s-1) at the input phosphor would seem to be justified under the test conditions since little improvement in CT is usually observed at higher kerma rates. However, application to clinical practice would ideally require the use of more realistic phantom studies. PMID:6657744

Harrison, R M; Day, M J

1983-11-01

45

New Air Quality Index  

Science.gov (United States)

On July 23, the US Environmental Protection Agency (EPA) announced the release of a new Air Quality Index, which is used by state and local agencies for reporting on daily air quality to the public, especially in major cities. The new Index has been revised to enhance public understanding of air quality and associated health effects, and it reflects updated health information on several pollutants. In addition to the full text of the new AQI Rule (105 p.), several related documents are offered at the site. These include the AQI fact sheet, Air Quality Guide, Ozone Health Effects Booklet, and Guideline for Reporting of Daily Air Quality.

United States. Environmental Protection Agency. Office of Air Quality Planning and Standards.

46

Conversion coefficients from air kerma to personal dose equivalent in mammography  

International Nuclear Information System (INIS)

In this work, the scattered X-ray beams produced by a mammography unit with a Mo/Mo, Mo/Rh and W/Rh anode/filter combinations were applied in the evaluation of the Hp(10,00) and mean conversion coefficients from air kerma to the personal dose equivalent (C-barHp(10,00)). The higher values of Hp(10,00) are related to the Mo/Rh combination whereas the lower ones are for the W/Rh target/filter. C-barHp(10,00) values are in the range 0.19-0.54 Sv/Gy, where the higher values comprise the W/Rh combination.

47

A conversion method of air kerma from the primary, scatter, and leakage radiations to effective dose for calculating x-ray shielding barriers in mammography  

International Nuclear Information System (INIS)

In this study, a new approach has been introduced for derivation of the effective dose from air kerma to calculate shielding requirements in mammography facilities. This new approach has been used to compute the conversion coefficients relating air kerma to the effective dose for the mammography reference beam series of the Netherlands Metrology Institute Van Swinden Laboratorium, National Institute of Standards and Technology, and International Atomic Energy Agency laboratories. The results show that, in all cases, the effective dose in mammography energy range is less than 25% of the incident air kerma for the primary and the scatter radiations and does not exceed 75% for the leakage radiation

48

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

International Nuclear Information System (INIS)

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

49

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)

50

Comparison of the standards for air kerma of the MKEH and the BIPM for {sup 137}Cs gamma radiation  

Energy Technology Data Exchange (ETDEWEB)

An indirect comparison of the standards for air kerma of the Magyar Kereskedelmi Engedelyezesi Hivatal (MKEH), Hungary, and of the Bureau International des Poids et Mesures (BIPM) was carried out in the {sup 137}Cs radiation beam of the BIPM in October 2009. The comparison result, expressed as a ratio of the MKEH and the BIPM calibration coefficients of a transfer chamber for air kerma, is 1.0053 with a combined standard uncertainty of 2.5 * 10{sup -3}. The result of the earlier direct comparison in {sup 137}Cs {gamma} rays, made in 1994, was 0.9954(30); taking into account the changes made recently to both standards, the 1994 result becomes 1.0038(30), in agreement with the present comparison result. (authors)

Kessler, C.; Allisy-Roberts, P.J. [Bureau International des Poids et Mesures (BIPM), 92 - Sevres (France); Csete, I.; Machula, G. [Magyar Kereskedelmi Engedelyezesi Hivatal (Hungary)

2010-06-15

51

Comparison of the standards for air kerma of the BEV and the BIPM for {sup 137}Cs gamma radiation  

Energy Technology Data Exchange (ETDEWEB)

A direct comparison of the standards for air kerma of the Bundesamt fur Eich- und Vermessungswesen (BEV), Austria, and of the Bureau International des Poids et Mesures (BIPM) was carried out in the {sup 137}Cs radiation beam of the BIPM in March 2009. The result, expressed as ratios of the BEV and the BIPM standards for air kerma, is 1.0041 with a combined standard uncertainty of 3.1 * 10{sup -3}. The result of the earlier direct comparison in {sup 137}Csgamma rays, made in 1995, was 0.9961 (28); taking into account the changes made recently to both standards, the 1995 result becomes 1.0035 (24), in agreement with the present comparison result. The degrees of equivalence between the BEV and the other participants in the key comparison have been calculated and the results are presented in the form of a matrix. A graphical presentation is also given. (authors)

Kessler, C.; Allisy, P.J.; Burns, D.T. [Bureau International des Poids et Mesures (BIPM), 92 - Sevres (France); Steurer, A.; Tiefenboeck, W.; Gabris, F. [Bundesamt fur Eich- und Vermessungswesen, Vienna (Austria)

2010-02-15

52

Comparison of the standards of air kerma of the OMH and the BIPM for 60Co gamma radiation  

International Nuclear Information System (INIS)

A direct comparison between the standards for air kerma of the Orszagos Meresugyi Hivatal (OMH) and of the Bureau International des Poids et Mesures (BIPM) has been carried out in the 60Co radiation beams of the BIPM. The result, expressed as a ratio of the OMH and the BIPM standards for air kerma, indicates a relative difference of 10.9 x 10-3 with a combined standard uncertainty of 2.2 x 10-3. This new result agrees at the level of 0.4 x 10-3 with the earlier direct comparisons performed in 1986 and 1994, as modified in 2001 by the application of wall and axial non-uniformity correction factors, calculated for the OMH standards using the Monte Carlo method. (authors)

53

Comparison of the standards of air kerma of the LNE-LNHB and the BIPM for 60Co gamma radiation  

International Nuclear Information System (INIS)

A direct comparison of the standards for air kerma of the Laboratoire National de Metrologie et d'Essais - Laboratoire National Henri Becquerel (LNE-LNHB), France and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 60Co radiation beam of the BIPM in December 2003. The results, expressed as ratios of the LNE-LNHB and the BIPM standards for air kerma, indicate a relative difference of 3.5 x 10-3 with a combined standard uncertainty of 2.7 x 10-3. The earlier direct comparison in 60Co ? rays, made in 1993, resulted in an agreement of the two standards within 2.5 x 10-3. (authors)

54

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)

55

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)

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)

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

56

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 alibration procedures have been developed to offer traceable calibration of the hospital well ionization chambers. (author)

57

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%

58

Evaluation of the entrance surface air kerma in mammographic examinations in Rio de Janeiro (Brazil)  

International Nuclear Information System (INIS)

The aim of this work was to evaluate the distribution of the entrance surface air kerma (ESAK) and the average glandular dose (DG) in four mammography facilities located in the city of Rio de Janeiro. The ESAK values were estimated from the X-ray tube output rate (mGy/mAs) parameters. The image quality was evaluated by the radiologists in each clinic. The ESAK values obtained for a breast thickness of 45 mm were 5.58 mGy in Clinic A, 10.07 mGy in Clinic B, 13.89 mGy in Clinic C and 7.21 mGy in Clinic D. For DG, it can be seen that, for the same compressed breast thickness (50 mm), the value varied from 0.20 to 3.60 mGy, with a mean value of 1.50 mGy for all the clinics. In image quality evaluation, Clinic D was the only one that presented a very low acceptability for quality criteria and inadequacies in relation to specks, masses and optical density. (authors)

59

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)

60

Assessment of natural radioactivity in soil samples and comparison of direct and indirect measurement of environmental air kerma rate  

International Nuclear Information System (INIS)

This study presents the high purity germanium (HPGe) gamma spectrometric measurement of natural radioactivity mainly due to 226Ra, 232Th and 40K in soil samples collected in Ferozepur and Faridkot district of Punjab, India. 226Ra activity varied from 28.6 to 51.1 Bq kg-1 with the mean of 39.7 Bq kg-1. The range and mean activity of 232Th were 42.9 - 73.2 and 58.2 Bq kg-1, respectively. 40K activity was in the range of 470.9 - 754.9 Bq kg-1 with the mean of 595.2 Bq kg-1. The air kerma rate (AKR) at 1 m height from the ground was also measured using gamma survey meter in all the sampling locations, which was ranging from 92.1 to 122.8 nGy h-1 with the mean of 110.6 nGy h-1. The radiological parameters such as Raeq and activity index of the soil samples were also evaluated, which are the tools to assess the external radiation hazard due to building materials. The mean and range of the Raeq values were 168.7 and 132.9 - 210.4 Bq kg-1, respectively, whereas the activity index varied from 0.5 to 0.8 with the mean value of 0.62. These indices show that the indoor external dose due to natural radioactivity in the soil used for the construction will not exceed the dose criteria. The AKR was also evaluated from soil activity concentration and altitude correction of cosmic radiation contribution. The statistical tests such as ntribution. The statistical tests such as Pearson correlation, spearman rank correlation, box and whisker plot, the Wilcoxon/Mann-Whitney test and chi-square test, were used to compare the measured AKR with evaluated AKR, which indicates good correlation. (author)

61

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)

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)

Ramos, Manoel Mattos Oliveira

2009-07-01

62

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)

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)

Ksouri, W

2008-12-15

63

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

DEFF Research Database (Denmark)

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.

Bargholz, Kim; Korsbech, Uffe C C

1997-01-01

64

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)

65

Ozone - Current Air Quality Index  

Science.gov (United States)

... 3/26/15: Updated Air Quality Guide for Ozone 2/03/15: Updated Ozone Facts webpage. more announcements Air Quality Basics Air Quality Index | Ozone | Particle Pollution | UV | Smoke from fires | What You ...

66

COOMET.RI(I)-K1 comparison of national measurement standards of air kerma for 60Co ? radiation  

International Nuclear Information System (INIS)

Results are presented of the COOMET key comparison of the national measurement standards of air kerma for 60Co ? radiation. Participants of the comparison were PTB (Germany, pilot institute), VNIIM (Russia), SMU (Slovakia), BelGIM (Belarus), CPHR (Cuba) and RMTC (Latvia). PTB, VNIIM and SMU had previously taken part in a key comparison with the Bureau International de Poids et Mesures (BIPM) and operated as link laboratories in order to evaluate the degree of equivalence of the participants' results with the key comparison reference value. These data form the basis of the results entered into the BIPM key comparison database for comparison COOMET.RI(I)-K1. (authors)

67

Summary of the BIPM.RI(I)-K5 comparison for air kerma in 137Cs gamma radiation  

International Nuclear Information System (INIS)

International comparisons of air kerma in 137Cs gamma radiation beams have been made at the Bureau International des Poids et Mesures (BIPM) since 1994. Twelve national metrology institutes have taken part, seven of which have repeated the comparison over the intervening years. The key comparison reference value (KCRV) is taken as the BIPM evaluation, each comparison result being the ratio of the national metrology institute (NMI) evaluation to that of the BIPM standard under the same reference conditions. The degrees of equivalence between each NMI and the KCRV and a graphical presentation are given using the most recent published result for eleven NMIs. (authors)

68

Air kerma to Hp(3) conversion coefficients for a new cylinder phantom for photon reference radiation qualities  

International Nuclear Information System (INIS)

The International Organization for Standardization (ISO) has issued a standard series on photon reference radiation qualities (ISO 4037). In this series, no conversion coefficients are contained for the quantity personal dose equivalent at a 3 mm depth, Hp(3). In the past, for this quantity, a slab phantom was recommended as a calibration phantom; however, a cylinder phantom much better approximates the shape of a human head than a slab phantom. Therefore, in this work, the conversion coefficients from air kerma to Hp(3) for the cylinder phantom are supplied for X- and gamma radiation qualities defined in ISO 4037. (authors)

69

Air kerma to Hp(3) conversion coefficients for a new cylinder phantom for photon reference radiation qualities.  

Science.gov (United States)

The International Organization for Standardization (ISO) has issued a standard series on photon reference radiation qualities (ISO 4037). In this series, no conversion coefficients are contained for the quantity personal dose equivalent at a 3 mm depth, H(p)(3). In the past, for this quantity, a slab phantom was recommended as a calibration phantom; however, a cylinder phantom much better approximates the shape of a human head than a slab phantom. Therefore, in this work, the conversion coefficients from air kerma to H(p)(3) for the cylinder phantom are supplied for X- and gamma radiation qualities defined in ISO 4037. PMID:22434922

Behrens, R

2012-09-01

70

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)

71

Measurement of conversion coefficients between air Kerma and personal dose equivalent and backscatter factors for diagnostic X-ray beams  

International Nuclear Information System (INIS)

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 cm3 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 133 Ba, 241 Am and 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)

72

Comparisons of the radiation protection standards for air kerma of the NIST and the BIPM for 60Co and 137Cs gamma radiation  

International Nuclear Information System (INIS)

An indirect comparison of the standards for air kerma of the National Institute of Standards and Technology (NIST), USA, and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 60Co and 137Cs radiation protection-level beams of the BIPM in September 2011. The comparison results, based on the calibration coefficient for two transfer standards and expressed as a ratio of the NIST and the BIPM standards for air kerma, are 1.0023 with a combined standard uncertainty of 3.2 * 10-3 in 60Co, and 0.9990 with a combined standard uncertainty of 3.5 * 10-3 in 137Cs. The result in the 60Co beam for radiation protection agrees within the uncertainties with the result of the comparison carried out at the same time in the CIS Bio 60Co beam for radiotherapy-level air kerma. (authors)

73

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 satisfactoryed 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.

74

KEY COMPARISON: Comparison of the standards for air kerma of the MKEH and the BIPM for 137Cs gamma radiation  

Science.gov (United States)

An indirect comparison of the standards for air kerma of the Magyar Kereskedelmi Engedélyezési Hivatal (MKEH), Hungary, and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 137Cs radiation beam of the BIPM in October 2009. The comparison result, expressed as a ratio of the MKEH and the BIPM calibration coefficients of a transfer chamber for air kerma, is 1.0053 with a combined standard uncertainty of 2.5 × 10-3. The result of the earlier direct comparison in 137Cs ? rays, made in 1994, was 0.9954(30); taking into account the changes made recently to both standards, the 1994 result becomes 1.0038(30), in agreement with the present comparison result. 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).

Kessler, C.; Allisy-Roberts, P. J.; Csete, I.; Machula, G.

2010-01-01

75

Evaluation of the air kerma rates values of x radiation systems used in calibration of measurement instruments in radiodiagnosis  

International Nuclear Information System (INIS)

In this work it was made the evaluation of the air kerma rates values obtained during the calibration of instruments used in diagnostic radiology measurements at the Calibration Laboratory of IPEN, as well as its variation according to the ambient conditions. This evaluation is part of the quality control programme of the reference instruments used in this type of calibration. The measurements carried out from August of 2003 to April of 2004 were analyzed for the Medicor X radiation system and from January to May of 2005 for the Seifert/Pantak X radiation system. Monitor chambers were added in the field in order to correct any possible variations in the electric beam that could cause an alteration in the primary beam for both X radiation systems. After the positioning of the monitor chambers a maximum decrease of 6.9 % for 90 kV in the primary beam was verified. After that the air kerma rates values presented a maximum variation of 8 %. The ambient conditions (temperature, pressure and humidity) control was made using appropriate calibrated instruments for each case. (author)

76

Comparison of the PTB and OMH air kerma standards for 60Co and 137Cs gamma radiation  

International Nuclear Information System (INIS)

A direct comparison between the primary air kerma standards of the PTB and OMH was carried out for 60Co and 137Cs ? rays in June 2000 within a time period of 1 month. The OMH standard is a graphite cavity chamber of the cylindrical type. The PTB standard is comprised of three graphite cavity chambers, different in shape and size. Two of them are of the cylindrical type and one of them is a pancake type chamber. The main technical parameters of the standards and the applied beams are described. The correction factors of the chambers are given together with their uncertainties. In particular, it is pointed out that for the first time calculated instead of measured wall correction factors were applied to all chambers. The ratios of air kerma rates measured with the PTB standard to those measured with the OMH standard were 1,0009 and 1,0011 for 60Co and 137Cs radiation, respectively. They are well within the stated relative standard uncertainties of the ratios of 0,22% for 60Co and 0,24% for 137Cs. The consistency of the results, which was obtained with ionisation chambers characterised by wall correction factors between 0,9980 and 1,0280 for 137Cs and between 1,0004 and 1,0212 for 60Co, is of special importance because it strongly confirms the validity of the calculation procedure to determine wall correction factors. (orig.)

77

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)

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.

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

2014-01-01

78

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

International Nuclear Information System (INIS)

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. (authors)

79

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

International Nuclear Information System (INIS)

A direct comparison of the standards for air kerma of the National Metrology Institute of Japan (NMIJ) and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 137Cs radiation protection-level beam of the BIPM in June 2012. The comparison result, expressed as a ratio of the NMIJ and the BIPM standards for air kerma, is 0.9977 with a combined standard uncertainty of 2.6 * 10-3. Taking into account the changes made to the BIPM standard, the result of the present comparison agrees within the uncertainties with the result of the direct comparison carried out in 2001. (authors)

80

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)

81

Conversion coefficients from air kerma to personal dose equivalent Hp(3) fir eye-lens dosimetry  

International Nuclear Information System (INIS)

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 Hp(3). A set of energy and angular dependent conversion coefficients Hp(3)/Kair in the new proposed square cylindrical phantom of ICRU tissue, have been calculated with the Monte-Carlo code PENELOPE. The Hp(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)

82

Comparison of the air-kerma standards of the BEV 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 BEV and the BIPM in the low-energy x-ray range. The results at the different radiation qualities show the standards to be in reasonable agreement with respect to the combined relative standard uncertainty of the comparison of 2.4 x 10-3. (authors)

83

Comparison of the air-kerma standards of the VNIIM and the BIPM in the medium-energy X-ray range  

International Nuclear Information System (INIS)

An indirect comparison has been made between the air-kerma standards of the VNIIM and the BIPM in the medium-energy x-ray range. The results show the standards to be in agreement within the stated uncertainty. (authors)

84

Measurement of air kerma rates for 6- to 7-MeV high-energy gamma-ray field by ionisation chamber and build-up plate  

International Nuclear Information System (INIS)

The 6- to 7-MeV high-energy gamma-ray calibration field by the 19F(p, ??)16O reaction is to be served at the Japan Atomic Energy Agency. For the determination of air kerma rates using an ionisation chamber in the 6- to 7-MeV high-energy gamma ray field, the establishment of the charged particle equilibrium must be achieved during measurement. In addition to measurement of air kerma rates by the ionisation chamber with a thick build-up cap, measurement using the ionisation chamber and a build-up plate (BUP) was attempted, in order to directly determine air kerma rates under the condition of regular calibration for ordinary survey meters and personal dosemeters. Before measurements, Monte Carlo calculations were made to find the optimum arrangement of BUP in front of the ionisation chamber so that the charged particle equilibrium could be well established. Measured results imply that air kerma rates for the 6- to 7-MeV high-energy gamma-ray field could be directly determined under the appropriate condition using an ionisation chamber coupled with build-up materials. (authors)

85

COOMET regional comparison of national measurement standards of air kerma for 137Cs ? radiation at protection level  

International Nuclear Information System (INIS)

Results are presented of the COOMET supplementary comparison of the national measurement standards for air kerma in 137Cs ? radiation at protection level (?10 mGy/h). Ten National Metrology Institutes from the COOMET organization and the International Atomic Energy Agency participated in this COOMET project no. 445. The PTB acted as pilot laboratory. Two of the participants, the SMU (Slovakia) and the NSC-'IM' (Ukraine) participated in the measurements but did not submit a valid report of results. The comparison reference value (CRV) was obtained as the mean result of the PTB and the VNIIM, both of which had previously taken part in the key comparison BIPM-RI(I)-K5. The degree of equivalence with the CRV was evaluated. The results were consistent within the relative standard uncertainties of the comparison ranging from 0.28% to 1.3% and deviated from the CRV by less than 1%. (authors)

86

COOMET.RI(I)-K1 comparison of national measurement standards of air kerma for {sup 60}Co {gamma} radiation  

Energy Technology Data Exchange (ETDEWEB)

Results are presented of the COOMET key comparison of the national measurement standards of air kerma for {sup 60}Co {gamma} radiation. Participants of the comparison were PTB (Germany, pilot institute), VNIIM (Russia), SMU (Slovakia), BelGIM (Belarus), CPHR (Cuba) and RMTC (Latvia). PTB, VNIIM and SMU had previously taken part in a key comparison with the Bureau International de Poids et Mesures (BIPM) and operated as link laboratories in order to evaluate the degree of equivalence of the participants' results with the key comparison reference value. These data form the basis of the results entered into the BIPM key comparison database for comparison COOMET.RI(I)-K1. (authors)

Buermann, L. [Physikalisch-Technische Bundesanstalt (PTB), Braunschweig (Germany); Oborin, A.V. [D I Mendeleyev Institute for Metrology (VNIIM), St Petersburg (Russian Federation); Dobrovosky, J. [3 Slovensky Metrologicky Ustav (SMU), Bratislava (Slovakia); Milevsky, V.S. [Belarussian State Institute for Metrology (BelGIM), Minsk (Belarus); Walwyn Salas, G. [Centro de Proteccion e Higiene de las Radiaciones (CPHR), Habana (Cuba); Lapenas, A. [Radiation Metrology and Testing Centre of the Latvian National Metrology Centre Ltd (RMTC), Salaspils (Latvia)

2009-12-15

87

Measurement of conversion coefficients between free in air kerma and personal dose equivalent for diagnostic X-ray beams  

Energy Technology Data Exchange (ETDEWEB)

Conversion coefficients between free in air kerma and personal dose equivalent were experimentally determined for the diagnostic X-ray qualities recommended by the International Electrotechnical Commission (IEC) for primary beams (RQR) and three RQA. Harshaw LiF-100H thermoluminescent dosemeters (TLD) were used for measurements after being calibrated against an ionization chamber traceable to the National Metrology Laboratory. A 300mmx300mmx150mm polymethilmethacrylate (PMMA) slab phantom was used for deep-dose measurements. The dosemeters were placed in the central axis of the X-ray beam at five different depths in the phantom (5, 10, 15, 25 and 35 mm) upstream the beam direction. The typical combined standard uncertainty of conversion coefficient value was 12%.

Rosado, P.H.G. [Centro de Desenvolvimento da Tecnologia Nuclear/CNEN, Belo Horizonte, MG (Brazil)], E-mail: phgr@cdtn.br; Nogueira, M.S. [Centro de Desenvolvimento da Tecnologia Nuclear/CNEN, Belo Horizonte, MG (Brazil)], E-mail: mnogue@cdtn.br; Genezini, F.; Vilela, E.C. [Centro Regional de Ciencias Nucleares/CNEN, Recife, PE (Brazil)

2008-02-15

88

Final report of the SIM {sup 60}Co Air-Kerma comparison (KCDB Entry SIM.RI(I)-K1)  

Energy Technology Data Exchange (ETDEWEB)

Transfer chambers were used to compare the standards for {sup 60}Co air kerma maintained by seven laboratories. Six of the laboratories are members of the Sistema Interamericano de Metrologia (SIM) regional metrology organization while the seventh is the International Atomic Energy Agency (IAEA) laboratory in Vienna. The National Research Council (NRC) acted as the pilot laboratory for the comparison. Because of the participation of laboratories holding primary standards, the comparison results could be linked to the key comparison reference value maintained by the Bureau International des Poids et Mesures (BIPM). The results for all laboratories were within the expanded uncertainty (two standard deviations) of the reference value. The estimated relative standard uncertainty of the comparison between any pair of laboratories ranged from 0.5% to 1.0%. The largest discrepancy between any two laboratories was 1.0%. (authors)

Ross, C.K.; Shortt, K.R. [National Research Council (NRC) (Canada); Saravi, M. [Comision Nacional de Energia Atomica (CNEA) (Argentina); Meghzifene, A. [International Atomic Energy Agency (IAEA), Vienna (Austria); Tovar, V.M. [ININ Mexico (Mexico); Barbosa, R.A.; Da Silva, C.N. [IRD, Rio de Janeiro, RJ (Brazil); Carrizales, L. [LSCD Venezuela (Venezuela); Seltzer, S.M. [National Institute of Standards and Technology (NIST) (United States)

2008-10-15

89

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)

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)

Sanchez, Mirtha Elizabet Gamarra

2008-07-01

90

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)

91

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 tereproducibility 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)

92

LNE-LNHB air-kerma and absorbed dose to water primary standards for low dose-rate 125I brachytherapy sources  

International Nuclear Information System (INIS)

The devices and methods applied for the LNE-LNHB primary standards in terms of reference air-kerma and absorbed dose to water for low dose-rate brachytherapy sources are described. Both standards are based on ionimetric measurements, using a circular-shaped free-in-air ionization chamber, and Monte Carlo calculated conversion factors. Results for an IBt Bebig 125I source are presented and used here to assess the dose-rate constant. Uncertainties of 1.5% and 1.6% (with k = 1) were found for the air-kerma rate and the absorbed dose to water rate estimated with the new primary standards. Good agreement was found between our values and the AAPM published dose-rate constants. Comparisons with other primary standards are in progress. (authors)

93

Calculation of the humidity correction factor in air kerma strength measurement for 125I and 103Pd brachytherapy sources and its uncertainty by Monte Carlo method  

International Nuclear Information System (INIS)

Highlights: ? Humidity can affect the measurement of air kerma strength. ? Humidity correction factor “khumidity” values are calculated by using a Monte Carlo method. ? Humidity correction factors are calculated for 2% to 100% relative humidity. ? khumidity shows a minimum at 10% relative humidity and a maximum at 100%. ? The uncertainty in khumidity is calculated to be about 0.2% for 125I and 103Pd sources. - Abstract: Humidity is one of the sources of systematic error in the absolute measurement of air kerma strength of 125I and 103Pd low energy brachytherapy sources by using free air ionization chambers. In this paper, the humidity correction factor and its uncertainty for several environmental conditions have been calculated by applying an indigenous developed uncertainty analysis algorithm programmed in FORTRAN. The results of the analysis showed that the humidity could affect the corrected measured source strength value by about 0.2%

94

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 esults are described and their estimation using Monte Carlo codes of particle transport are presented for the Bebig iodine seed sources, referenced I125 S16

95

Determination of air-kerma strength for the {sup 192}Ir GammaMedplus iX pulsed-dose-rate brachytherapy source  

Energy Technology Data Exchange (ETDEWEB)

Purpose: Pulsed-dose-rate (PDR) brachytherapy was originally proposed to combine the therapeutic advantages of high-dose-rate (HDR) and low-dose-rate brachytherapy. Though uncommon in the United States, several facilities employ pulsed-dose-rate brachytherapy in Europe and Canada. Currently, there is no air-kerma strength standard for PDR brachytherapy {sup 192}Ir sources traceable to the National Institute of Standards and Technology. Discrepancies in clinical measurements of the air-kerma strength of the PDR brachytherapy sources using HDR source-calibrated well chambers warrant further investigation.Methods: In this research, the air-kerma strength for an {sup 192}Ir PDR brachytherapy source was compared with the University of Wisconsin Accredited Dosimetry Calibration Laboratory transfer standard well chambers, the seven-distance technique [B. E. Rasmussen et al., 'The air-kerma strength standard for 192Ir HDR sources,' Med. Phys. 38, 6721-6729 (2011)], and the manufacturer's stated value. Radiochromic film and Monte Carlo techniques were also employed for comparison to the results of the measurements.Results: While the measurements using the seven-distance technique were within + 0.44% from the manufacturer's determination, there was a + 3.10% difference between the transfer standard well chamber measurements and the manufacturer's stated value. Results showed that the PDR brachytherapy source has geometric and thus radiological qualities that exhibit behaviors similar to a point source model in contrast to a conventional line source model.Conclusions: The resulting effect of the pointlike characteristics of the PDR brachytherapy source likely account for the differences observed between well chamber and in-air measurements.

Riley, A. D.; Pike, T. L.; Micka, J. A.; Fulkerson, R. K.; DeWerd, L. A. [Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin 53705 (United States)

2013-07-15

96

Comparison of national air kerma standards for ISO 4037 narrow spectrum series in the range 30 kV to 300 kV  

International Nuclear Information System (INIS)

For the first time results are presented of an indirect comparison of ten national standards for air kerma for ten radiation qualities of the ISO 4037 narrow spectrum series in the range from 30 kV to 300 kV. Nine of the ten participants maintain primary air kerma standards, one is traceable to PTB. The comparison was conducted in the time period from February 2004 until October 2005. For each radiation quality, the results are analysed in terms of the degrees of equivalence of each national standard with respect to the comparison reference value. These data form the basis of the results in the BIPM key comparison database for comparison EUROMET.RI(I)-S3. In addition, results are presented of differences in the results due to different realizations of beam qualities at the participants' sites and of the influence of different transfer chamber sizes on the variance of the comparison results. (authors)

97

Comparison of national air kerma standards for ISO 4037 narrow spectrum series in the range 30 kV to 300 kV  

Energy Technology Data Exchange (ETDEWEB)

For the first time results are presented of an indirect comparison of ten national standards for air kerma for ten radiation qualities of the ISO 4037 narrow spectrum series in the range from 30 kV to 300 kV. Nine of the ten participants maintain primary air kerma standards, one is traceable to PTB. The comparison was conducted in the time period from February 2004 until October 2005. For each radiation quality, the results are analysed in terms of the degrees of equivalence of each national standard with respect to the comparison reference value. These data form the basis of the results in the BIPM key comparison database for comparison EUROMET.RI(I)-S3. In addition, results are presented of differences in the results due to different realizations of beam qualities at the participants' sites and of the influence of different transfer chamber sizes on the variance of the comparison results. (authors)

Buermann, L. [Physikalisch-Bundesanstalt (PTB), Braunschweig (Germany); O' Brien, M. [National Institute of Standards and Technology (NIST), Gaithersburg (United States); Butler, D. [Australian Radiation Protection and Nuclear Safety Agency (ARPANSA), Victoria (Australia); Csete, I. [National Office of Measures (OMH), Budapest (Hungary); Gabris, F. [Bundesamt fur Eich- und Vermessungswesen (BEV), Wien (Austria); Hakanen, A. [Radiation and Nuclear Safety Authority (STUK), Helsinki (Finland); Lee, J.H. [National Radiation Standard Laboratory, Institute of Nuclear Energy Research (INER), Lungtan, Taiwan (China); Palmer, M. [National Physical Laboratory (NPL), Teddington (United Kingdom); Saito, N. [National Metrology Institute of Japan (NMIJ), National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba (Japan); Vries, W. de [NMi Van Swinden Laboratorium, Utrecht (Netherlands)

2008-12-15

98

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)

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).

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

2015-01-01

99

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)

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).

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

2014-01-01

100

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)

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).

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

2014-01-01

101

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)

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).

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

2014-01-01

102

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

Science.gov (United States)

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. 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).

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

2014-01-01

103

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

Science.gov (United States)

An indirect comparison of the standards for reference air kerma rate for 192Ir high dose rate brachytherapy sources of the National Physical Laboratory (NPL), United Kingdom, and of the Bureau International des Poids et Mesures (BIPM) was carried out at the NPL in June 2010. The comparison result, based on the calibration coefficients for a transfer standard and expressed as a ratio of the NPL and the BIPM standards for reference air kerma rate, is 0.9989 with a combined standard uncertainty of 0.0057. 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).

Alvarez, J. T.; Sander, T.; de Pooter, J. A.; Allisy-Roberts, P. J.; Kessler, C.

2014-01-01

104

Key comparison BIPM.RI(I)-K7 of the air-kerma standards of the NIST, USA 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 NIST 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 3.2 parts in 103. The results are analysed and presented in terms of degrees of equivalence for entry in the BIPM key comparison database. (authors)

105

Technical aspects of the dissemination of the air-kerma standard from 137Cs gamma-ray beams in the United States  

International Nuclear Information System (INIS)

The national standard for air kerma from gamma-ray beams is maintained in the U.S. by the National Institute of Standards and Technology (NIST), the primary standard radiation dosimetry laboratory in the U.S. The standard is disseminated throughout the U.S. by a well established network of instrument calibration facilities. The main tool used at both NIST and at these calibration facilities for disseminating the national standard are radioactive cesium irradiators. The output of these cesium irradiators is well known at each one of the calibration facilities and is therefore used for calibrating radiation detection equipment in terms of the radiation quantity air kerma. This ensures the accuracy of measurements performed with radiation detection equipment used in numerous types of applications throughout the country. In this paper a brief description of the standards program at NIST will be presented including the dissemination of the national standard for air kerma from gamma-ray beams throughout the U.S. Technical aspects of the operation of the NIST facilities will be described. (author)

106

Comparisons of the radiation protection standards for air kerma of the NIST and the BIPM for 60Co and 137Cs gamma radiation  

Science.gov (United States)

An indirect comparison of the standards for air kerma of the National Institute of Standards and Technology (NIST), USA, and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 60Co and 137Cs radiation protection-level beams of the BIPM in September 2011. The comparison results, based on the calibration coefficient for two transfer standards and expressed as a ratio of the NIST and the BIPM standards for air kerma, are 1.0023 with a combined standard uncertainty of 3.2 × 10-3 in 60Co, and 0.9990 with a combined standard uncertainty of 3.5 × 10-3 in 137Cs. The result in the 60Co beam for radiation protection agrees within the uncertainties with the result of the comparison carried out at the same time in the CIS Bio 60Co beam for radiotherapy-level air kerma. 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).

Kessler, C.; Allisy-Roberts, P. J.; Minniti, R.

2014-01-01

107

COOMET regional comparison of national measurement standards of air kerma for 137Cs ? radiation at protection level  

Science.gov (United States)

Results are presented of the COOMET supplementary comparison of the national measurement standards for air kerma in 137Cs ? radiation at protection level (~10 mGy/h). Ten National Metrology Institutes from the COOMET organization and the International Atomic Energy Agency participated in this COOMET project no. 445. The PTB acted as pilot laboratory. Two of the participants, the SMU (Slovakia) and the NSC-'IM' (Ukraine) participated in the measurements but did not submit a valid report of results. The comparison reference value (CRV) was obtained as the mean result of the PTB and the VNIIM, both of which had previously taken part in the key comparison BIPM-RI(I)-K5. The degree of equivalence with the CRV was evaluated. The results were consistent within the relative standard uncertainties of the comparison ranging from 0.28% to 1.3% and deviated from the CRV by less than 1%. 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).

Büermann, L.; Oborin, A. V.; Milevsky, V. S.; Walwyn Salas, G.; Sukhishvili, S.; Ginga, I.; Ivanov, R.; Gudelis, A.; Gomola, I.

2014-01-01

108

Kerma in the air at entry surface in thorax pediatric examinations at public hospital in Parana, Brazil  

International Nuclear Information System (INIS)

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)

109

KEY COMPARISON: COOMET.RI(I)-K1 comparison of national measurement standards of air kerma for 60Co ? radiation  

Science.gov (United States)

Results are presented of the COOMET key comparison of the national measurement standards of air kerma for 60Co ? radiation. Participants of the comparison were PTB (Germany, pilot institute), VNIIM (Russia), SMU (Slovakia), BelGIM (Belarus), CPHR (Cuba) and RMTC (Latvia). PTB, VNIIM and SMU had previously taken part in a key comparison with the Bureau International de Poids et Mesures (BIPM) and operated as link laboratories in order to evaluate the degree of equivalence of the participants' results with the key comparison reference value. These data form the basis of the results entered into the BIPM key comparison database for comparison COOMET.RI(I)-K1. 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).

Büermann, L.; Oborin, A. V.; Dobrovosky, J.; Milevsky, V. S.; Walwyn Salas, G.; Lapenas, A.

2009-01-01

110

Summary of the BIPM.RI(I)-K5 comparison for air kerma in 137Cs gamma radiation  

Science.gov (United States)

International comparisons of air kerma in 137Cs gamma radiation beams have been made at the Bureau International des Poids et Mesures (BIPM) since 1994. Twelve national metrology institutes have taken part, seven of which have repeated the comparison over the intervening years. The key comparison reference value (KCRV) is taken as the BIPM evaluation, each comparison result being the ratio of the national metrology institute (NMI) evaluation to that of the BIPM standard under the same reference conditions. The degrees of equivalence between each NMI and the KCRV and a graphical presentation are given using the most recent published result for eleven NMIs. 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).

Allisy-Roberts, P. J.; Kessler, C.; Burns, D. T.

2013-01-01

111

Air kerma standard and measurement comparison on source strength determination for high-dose rate 192Ir brachytherapy in Taiwan  

International Nuclear Information System (INIS)

This paper describes the establishment by the Inst. of Nuclear Energy Research (INER Taiwan (CN)) of the reference air kerma rate (RAKR) calibration standard for measurement of high-dose rate (HDR) 192Ir brachytherapy source strength. A bilateral comparison has been made in the RAKR standards for HDR 192Ir brachytherapy sources at the INER and Physikalisch-Technische Bundesanstalt (PTB (Germany)) and the measurement difference was within the overall standard uncertainty and showed good agreement between the two calibration standard systems established at the INER and the PTB. Besides, INER also worked with 20 domestic hospitals to organise an on-site measurement comparison programme to explore the status of HDR 192Ir brachytherapy source strength determination in Taiwan. The comparison results presented the ratios of RAKR with vendor values, as determined by INER and hospitals from the programme. The ratios fall in all cases within the ± 3 % guaranteed by the vendors for a coverage factor of k=2 or at 95 % confidence level. (authors)

112

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)

113

Accuracy of Spencer-Attix cavity theory and calculations of fluence correction factors for the air kerma formalism  

International Nuclear Information System (INIS)

EGSnrc calculations of ion chamber response and Spencer-Attix (SA) restricted stopping-power ratios are used to test the assumptions of the SA cavity theory and to assess the accuracy of this theory as it applies to the air kerma formalism for 60Co beams. Consistent with previous reports, the EGSnrc calculations show that the SA cavity theory, as it is normally applied, requires a correction for the perturbation of the charged particle fluence (Kfl) by the presence of the cavity. The need for Kfl corrections arises from the fact that the standard prescription for choosing the low-energy threshold ? in the SA restricted stopping-power ratio consistently underestimates the values of ? needed if no perturbation to the fluence is assumed. The use of fluence corrections can be avoided by appropriately choosing ?, but it is not clear how ? can be calculated from first principles. Values of ? required to avoid Kfl corrections were found to be consistently higher than ? values obtained using the conventional approach and are also observed to be dependent on the composition of the wall in addition to the cavity size. Values of Kfl have been calculated for many of the graphite-walled ion chambers used by the national metrology institutes around the world and found to be within 0.04% of unity in all cases, with an uncertainty of about 0.02%.

114

Theoretical considerations of using in-air chamber readings for evaluation of the attenuation of in-phantom primary water collision kerma  

International Nuclear Information System (INIS)

In treatment planning of photon radiation therapy, obtaining accurate attenuation of in-phantom primary water collision kerma is important for accurate evaluation of the in-phantom primary and scatter absorbed dose. In-air chamber readings are often taken for evaluation of the attenuation of in-phantom primary water collision kerma. Using the Awall concept, theoretical consideration is given to the evaluation method and the following conclusions are drawn: For beams with multiple photon energies, the evaluation method can be perfectly valid only under certain extreme conditions. However, if the build-up cap is made of a low Z material like acrylic or aluminum and if its thickness is approximately equal to what is required for maximum dose build-up, the evaluation method can be valid with a high degree of accuracy. For beams with a single photon energy, the evaluation method can be perfectly valid without any particular conditions. (author)

115

Coomet Project 445: Comparison of National Measurement Standards of Air Kerma for Cs-137 Gamma Radiation at Protection Level  

International Nuclear Information System (INIS)

A COOMET supplementary comparison of the national measurement standards of air kerma for Cs-137 gamma radiation at protection level (?10 mGy/h) was carried out between May 2011 and February 2013. Participants were VNIIM (Russia), BelGIM (Belarus), CPHR (Cuba), GEOSTM (Georgia), INSM (Moldova), NSC-'IM' (Ukraine), SMU (Slovakia), PTB (Germany), BIM (Bulgaria), VMT/FTMC (Lithuania) and the International Atomic Energy Agency (IAEA). The PTB acted as the pilot laboratory. The comparison reference value (CRV) was obtained as the mean of the results obtained by PTB and VNIIM, both of which had previously taken part in the key comparison BIPM-RI (I)-K5. Results will be published in Appendix B of the BIPM key comparison database (KCDB) using the identifier COOMET.RI(I)-S1 as soon as the Draft B report is accepted. The comparison was organized within an extended COOMET project (identified as Project 445/DE/08), the aim of which was not only to compare national standards but also for educational purposes. Some of the participants had taken part in such a comparison for the first time and, therefore, an introductory seminar was held at PTB in May 2011. The seminar was open for participation also to those countries of the COOMET region which did not participate in the comparison and to nonMRA signatories and countries without an approved quality management system in order to acquire measurement routine and theoretical as well as organizational knowledge for future comparisons. The main goal of this seminar was to prepare the participants for the procedure of having entries accepted for the CMC list in the metrological area of Ionising Radiation, Section I, x and gamma rays

116

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

117

Measurement of kVp, PPV and air kerma values in function of the electric current quantity and the focus-detector distance in one X-ray equipment  

International Nuclear Information System (INIS)

The objective of this work was to study the behavior of the X-ray equipment Pantak/Seifert, model MXR-160/22 of the calibration laboratory of IPEN, LCI, operating in the diagnostic radiology radiation quality RQR 5 (70 kV). For this evaluation it was used a noninvasive meter PTW, DiavoltTM model. The measurements of kVp, PPV and Dose (air kerma), were made varying the electric current and distance between the focal point and the meter. This behavior is described in the literature and was expected in the analysis of the measurements for comparison purposes. For the tests where it was only increased the electric current it was waited a linear increase of the dose (air kerma), but not a variation in the kVp and PPV. The measurements had corresponded to the waited behavior, since the Dose (air kerma) measurements presented a linear increase with the increase of the electric current and the kVp and PPV values showed a variation less than 2%. In the corresponding measurements increasing the distance between focal point and meter, it was waited the exponentially decreasing of the Dose (air kerma) and again a small variation or no variation of the PPV and kVP with the increase of the distance. Over again the measurements corresponded to the expected, where the Dose (air kerma) decreased exponentially and the PPV and the kVp had a variation less than 1.5%. (author)

118

A PROPOSED UNIFORM AIR POLLUTION INDEX  

Science.gov (United States)

A uniform air pollution index for the U.S. is proposed. The index was developed from ten criteria identified in a survey of all the air pollution indices currently in use in the U.S. and Canada. The proposed index, named the Pollutant Standards Index (PSI), was designed to overco...

119

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)

120

Key comparison BIPM.RI(I)-K2 of the air-kerma standards of the NIST, USA 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 NIST and the BIPM in the low-energy x-ray range. The results show the standards to be in general agreement at the level of the combined standard uncertainty for the comparison of 4.1 parts in 103, although the results for the different radiation qualities show variations that are larger than would be expected. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. (authors)

121

Recent regional key comparison results for air kerma and absorbed dose to water in X-rays and 60Co radiation  

International Nuclear Information System (INIS)

Degrees of equivalence (DoE) of the national standards as a result of periodically organized supporting key or supplementary comparisons are essential to maintain the calibration and measurement capabilities CMC lines in the database of the CIPM MRA. All the primary and secondary' standard dosimetry laboratories belong to at least one of the APMP, AFRIMETS, COOMET, EURAMET, and SIM Regional Metrology Organizations. Most of their host country's NMIs have signed the CIPM MRA and these NMIs or Designated Institutes (DI) in 32 countries worldwide have published dosimetry CMC's. From these 941 claims, 222 relate to the calibration of a wide variety of dosemeters in term of air kerma or absorbed dose to water being used in diagnostic or therapy practice in hospitals. In the case of low and medium energy X-ray beam qualities, one regional key comparison (APMP.RI (I)-K3) has been published and has some results that do not fully support the stated uncertainties of the participants. The other two similar comparisons (APMP.RI (I)-K-2, SIM.RI (I)-K-2) are still ongoing. For air kerma of the 60Co beam from the APMP.RI(I)-K1, SIM.RI(I)-K1 and EURAMET.RI(I)-K1 comparisons there are two results among the twenty-one recently established DoE values that is outside the expanded uncertainty. Further technical details of regional comparisons including the stated uncertainty budgets for the calibration of a typical therapy ionization chamber will be presented in the poster. Concmber will be presented in the poster. Concerning the future regional key and supplementary comparison program the most important issues are the following: - encourage the dosimetry laboratories to organise and coordinate these comparisons, - more economic arrangement of the X-ray comparisons on the basis of the generic beam qualities of the 85 standard qualities, - organization of supplementary comparisons in term of air kerma length to support the CT dose measurements, - using dedicated mammography X-ray tube for air kerma comparisons of mammography beam qualities, - new comparisons involving the radiation of the brachytherapy sources in terms of absorbed dose to water in the vicinity of the seeds, - new Dw comparisons for high energy accelerator beams to have more information about the different high energy accelerator beams

122

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)

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

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

123

Determination of distance error and scatter correction factor used in measurement of reference air kerma rate of high dose rate 192Ir source  

International Nuclear Information System (INIS)

192Ir sources are being increasingly used in high dose rate (HDR) brachytherapy treatment of malignant diseases. The accuracy of dose delivery to the tumor directly depends on the accuracy of the source strength. It is therefore essential to calibrate accurately the strength of HDR sources so that prescribed dose can be delivered to the tumour within stipulated limit. The ICRU, BCRU (UK), BIPM (France) and IAEA have recommended specifying brachytherapy sources in term of reference air kerma rate (RAKR) while NIST (USA) recommends the quantity air kerma strength (AKS). IAEA recommends the use of 1.0 cm3 (approx.) cylindrical chamber in addition to suitable well-type chamber for the RAKR measurement of HDR sources. To determine RAKR or AKS by cylindrical chambers, it is required to know the distance error and room scatter contribution precisely. The seven-distance measurement technique has been recommended to determine these two parameters. In this method, output of the source in air, Md' is the sum of primary and scattered radiation. Two different methods were used to estimate c, Ms and f which are the subject matter of this paper

124

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

Science.gov (United States)

A direct comparison of the standards for air kerma of the National Metrology Institute of Japan (NMIJ) and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 137Cs radiation protection-level beam of the BIPM in June 2012. The comparison result, expressed as a ratio of the NMIJ and the BIPM standards for air kerma, is 0.9977 with a combined standard uncertainty of 2.6 × 10-3 Taking into account the changes made to the BIPM standard, the result of the present comparison agrees within the uncertainties with the result of the direct comparison carried out in 2001. 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).

Kessler, C.; Saito, N.; Kurosawa, T.

2013-01-01

125

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 ? 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)

126

Comparisons of the standards for air kerma of the PTB and the BIPM for {sup 60}Co and {sup 137}Cs gamma radiation  

Energy Technology Data Exchange (ETDEWEB)

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 {sup 60}Co and {sup 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 {sup 60}Co of 9.9 x 10{sup -3} with a combined standard uncertainty of 1.8 x 10{sup -3}, and in {sup 137}Cs of 6.4 x 10{sup -3} with a combined standard uncertainty of 2.8 x 10{sup -3}. The earlier comparisons in {sup 60}Co {gamma} rays made in 1971 (direct) and 1989 (indirect) resulted in an agreement of the two standards within 2 x 10{sup -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, k{sub wall} and k{sub pn}, for the PTB standards, which were calculated using Monte Carlo methods. (authors)

Allisy-Roberts, P.J.; Burns, D.T. [Bureau International des Poids et Mesures (BIPM), 92 - Sevres (France); Buermann, L.; Kramer, H.M. [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany)

2005-11-15

127

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

128

CORRIGENDUM: Diaphragm correction factors for free-air chamber standards for air kerma in x-rays Diaphragm correction factors for free-air chamber standards for air kerma in x-rays  

Science.gov (United States)

The paper describes the Monte Carlo calculation of diaphragm correction factors for free-air ionization chamber standards. Although not submitted for publication until December 2008, this work was carried out in 2006 and preliminary results were presented at the World Congress on Medical Physics and Biomedical Engineering of that year (Kessler 2006). Subsequently, Mainegra-Hing et al (2008) published the results of similar calculations for their own standard. In retrospect, the authors regret that they did not take the opportunity to revise their manuscript to include a citation to the work of Mainegra-Hing et al. The following sentence should be added at the end of the second paragraph of section 7 (Discussion) on page 2744 (following the text '...correction for diaphragm scatter.'): 'In a more recent work, Mainegra-Hing et al (2008) calculated a combined correction for diaphragm transmission and scatter of 0.9984 for their 250 kV measurement conditions. This is in agreement with the value 0.9983(3) obtained in the present work.' References Kessler C 2006 Calculation of the aperture scatter and transmission correction factors for the BIPM free-air chamber standards using the code PENELOPE World Congress on Medical Physics and Biomedical Engineering (27 August-1 September 2006, Seoul, Korea) Mainegra-Hing E, Reynaert N and Kawrakow I 2008 Novel approach for the Monte Carlo calculation of free-air chamber correction factors Med. Phys. 35 3650-60

Burns, D. T.; Kessler, C.

2009-07-01

129

Where should we measure the entrance air kerma rate during acceptance testing of the automatic dose control of a fluoroscopic system?  

Science.gov (United States)

In Japan, the entrance air kerma rate (EAKR) to a patient cannot exceed 50 mGy/min in conventional fluoroscopy. However, it is unclear where the EAKR should be measured. We obtained the tube potential and tube current as a function of polymethylmethacrylate (PMMA) thickness, and the EAKR at the interventional reference point (IRP) was measured from the trajectory. The EAKR at the point established by the U.S. Food and Drug Administration (FDA) was calculated from EAKR at the IRP. The EAKR at the IRP exceeded the limit at a PMMA thickness of 22-28 cm. However, the EAKR did not exceed the limit at the FDA point. If the EAKR to a patient is being verified to meet the recent Japanese ruling, the EAKR should be measured at the FDA point, and if the EAKR is being evaluated for determination of the skin dose, it should be monitored at the IRP. PMID:23413079

Fukuda, Atsushi; Miyati, Tosiaki; Matsubara, Kosuke

2013-07-01

130

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

Science.gov (United States)

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. 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).

Burns, D. T.; Kessler, C.; Tanaka, T.; Kurosawa, T.; Saito, N.

2015-01-01

131

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

Science.gov (United States)

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. 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).

Kessler, C.; Burns, D. T.; Steurer, A.; Tiefenboeck, W.; Bauer, M.

2015-01-01

132

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

Science.gov (United States)

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. 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).

Burns, D. T.; Kessler; Steurer, A.; Tiefenboeck, W.; Bauer, M.

2015-01-01

133

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

Science.gov (United States)

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. 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).

Burns, D. T.; Kessler, C.; Steurer, A.; Tiefenboeck, W.; Bauer, M.

2015-01-01

134

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

Science.gov (United States)

A key comparison has been made between the air-kerma standards of the PTB, Germany 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 of the comparison of 2.1 parts in 103. The results are analysed and presented in terms of degrees of equivalence, 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).

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

2014-01-01

135

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

Science.gov (United States)

A first key comparison has been made between the air-kerma standards of the VSL and the BIPM in mammography x-ray beams. The results show the standards to be in agreement within the standard uncertainty of 5.7 parts in 103. 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).

Kessler, C.; Burns, D. T.; de Prez, L.; Joulaeizadeh, L.

2014-01-01

136

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

Science.gov (United States)

A key comparison has been made between the air-kerma standards of the PTB, Germany 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 5.0 parts in 103. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. 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).

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

2014-01-01

137

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

Science.gov (United States)

A key comparison has been made between the air-kerma standards of the ENEA, Italy 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 6.2 parts in 103. The results are analysed and presented in terms of degrees of equivalence, 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).

Burns, D. T.; Kessler, C.; Pinto, M.; Cappadozzi, G.; Silvestri, C.; Toni, M. P.

2014-01-01

138

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)

139

Use of a new breast phantom for dosimetric determination of incident air kerma and mean glandular dose in digital mammography system  

Energy Technology Data Exchange (ETDEWEB)

Mammography aims to achieve a high image quality associated with a dose in the patient as low as feasible. Values of average glandular dose, D{sub G}, can be obtained by means of two dosimetric methods: one based on the measurement of incident air kerma, K{sub i}, associated with tables of conversion factors that depend on the half value layer, the thickness and the glandular composition of the breast. And the one that makes the measure directly to thermoluminescent dosimeters, TLDs, placed in a new dosimetric phantom. Thus, this study aims to determine the incident air kerma (K{sub i}) and average glandular dose (D{sub G}) applied on patients in a digital mammography system (DR) using the phantom dosimetric developed. Another objective is to compare the results with the values of D{sub G} determined from K{sub i} and also with the values of K{sub i} and D{sub G} indicated in the examination of each patient by the digital mammography unit. The result of the average values measured in 77 patients with compressed breast thickness within the range of 5.5 cm and 6.5 cm, shows that the K{sub i} values ranged around 7.9% between the methods of action. The result of the values of D{sub G} ranged around 14.7% between the two methods of action. It is observed that the estimate of D{sub G} by the software is higher than the values measured with the dosimetric phantom. (author)

Coutinho, Celia M.C.; Almeida, Claudio D. de, E-mail: celia@ird.gov.b, E-mail: claudio@ird.gov.b [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil); Peixoto, Joao E., E-mail: joao.e.peixoto@uol.com.b [Instituto Nacional de Cancer (INCa/RJ), Rio de Janeiro, RJ (Brazil); Lopes, Ricardo T., E-mail: ricardo@lin.ufrj.b [Coordenacao dos Programas de Pos-graduacao de Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear

2009-07-01

140

KERMA ratios in pediatric CT dosimetry  

Energy Technology Data Exchange (ETDEWEB)

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.)

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

141

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)

142

Neutron kerma factors, and water equivalence of some tissue substitutes  

Energy Technology Data Exchange (ETDEWEB)

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{sup -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)

Singh, V. P.; Badiger, N. M. [Karnatak University, Department of Physics, Dharwad, 580003 (India); Vega C, H. R., E-mail: kudphyvps@rediffmail.com [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico)

2014-08-15

143

Radiological investigations at the "Taiga" nuclear explosion site, part II: man-made ?-ray emitting radionuclides in the ground and the resultant kerma rate in air.  

Science.gov (United States)

Samples of soil and epigeic lichens were collected from the "Taiga" peaceful nuclear explosion site (61.30°N 56.60°E, the Perm region, Russia) in 2009 and analyzed using high resolution ?-ray spectrometry. For soil samples obtained at six different plots, two products of fission ((137)Cs and (155)Eu), five products of neutron activation ((60)Co, (94)Nb, (152)Eu, (154)Eu, (207)Bi) and (241)Am have been identified and quantified. The maximal activity concentrations of (60)Co, (137)Cs, and (241)Am for the soils samples were measured as 1650, 7100, and 6800 Bq kg(-1) (d.w.), respectively. The deposit of (137)Cs for the top 20 cm of soil on the tested plots at the "Taiga" site ranged from 30 to 1020 kBq m(-2); the maximal value greatly (by almost 3 orders of magnitude) exceeded the regional background (from global fallout) level of 1.4 kBq m(-2). (137)Cs contributes approximately 57% of the total ground inventory of the man-made ?-ray emitters for the six plots tested at the "Taiga" site. The other major radionuclides -(241)Am and (60)Co, constitute around 40%. Such radionuclides as (60)Co, (137)Cs, (241)Am, and (207)Bi have also been determined for the epigeic lichens (genera Cladonia) that colonized certain areas at the ground lip produced by the "Taiga" explosion. Maximal activity concentrations (up to 80 Bq kg(-1) for (60)Co, 580 Bq kg(-1) for (137)Cs, 200 Bq kg(-1) for (241)Am, and 5 Bq kg(-1) for (207)Bi; all are given in terms of d.w.) have been detected for the lower dead section of the organisms. The air kerma rates associated with the anthropogenic sources of gamma radiation have been calculated using the data obtained from the laboratory analysis. For the six plots tested, the kerma rates ranged from 50 to 1200 nGy h(-1); on average, 51% of the dose can be attributed to (137)Cs and 45% to (60)Co. These estimates agree reasonably well with the results of the in situ measurements made during our field survey of the "Taiga" site in August 2009. PMID:22541991

Ramzaev, V; Repin, V; Medvedev, A; Khramtsov, E; Timofeeva, M; Yakovlev, V

2012-07-01

144

APMP/TCRI key comparison report of measurement of air kerma for medium-energy x-rays (APMP.RI(I)-K3)  

International Nuclear Information System (INIS)

The APMP/TCRI Dosimetry Working Group performed the APMP.RI(I)-K3 key comparison of measurement of air kerma for medium-energy x-rays (100 kV to 250 kV) between 2000 and 2003. In total, 11 institutes took part in the comparison, among which 8 were APMP member laboratories. Two commercial cavity ionization chambers were used as transfer instruments and circulated among the participants. All the participants established the 100 kV, 135 kV, 180 kV and 250 kV x-ray beam qualities equivalent to those of the BIPM. The results showed that the maximum difference between the participants and the BIPM in the medium-energy x-ray range, evaluated using the comparison data of the linking laboratories ARPANSA and PTB, is less than 1.4%. The degrees of equivalence between the participants are presented and this comparison confirms the calibration capabilities of the participating laboratories. (authors)

145

Monte Carlo investigation of influence of Titanium k X-rays on air-kerma strength and dose rate constant of 125I brachytherapy sources  

International Nuclear Information System (INIS)

Recently the number of 125I brachytherapy sources and its applications has dramatically increased in the treatment of the eye, brain, head and neck region and in permanent implant for early stage prostate cancer. The active material of all these sources is in the form of silver rod or sphere, coated with radioactive layer and encapsulated in titanium tube. The photoelectric interaction of 125I photons with titanium (Ti) encapsulation generates K-shell characteristic x-rays of energy ?5 keV. These x-rays are totally absorbed in tissue within 1 mm of the source (mean free path in water is only 0.23 mm) and thus do not contribute to the dose rate constant ?. NIST in 1999, proposed that these x-rays should be excluded while determining air-kerma strength Sk. In the present work we investigate the influence of the above-mentioned x-rays on the calculated values of Sk and ? for few commercial models of 125I sources. The geometry details of the investigated sources are significantly different from each other. Monte Carlo-based MCNP code with updated photon cross-section library is used for this purpose

146

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)

147

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)

148

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

149

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

Science.gov (United States)

A key comparison has been made between the air-kerma standards of the VSL, Netherlands and the BIPM in the low-energy x-ray range. The results for the direct comparison show the standards to be in general agreement for the 10 kV, 30 kV and 25 kV radiation qualities at the level of the expanded uncertainty for the comparison of 6.6 parts in 103. For the 50 kV qualities, differences approaching twice the expanded uncertainty are observed. The results for an indirect comparison made at the same time are not consistent with the direct results, in the worst case (10 kV) differing by 4 parts in 102. The results are analysed and presented in terms of degrees of equivalence, 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).

Burns, D. T.; Kessler, C.; de Prez, L.; Joulaeizadeh, L.

2014-01-01

150

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 hambers, 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.

151

Direct reference air-kerma rate calibration of 192Ir for a thimble-type ionization chamber in a cylindrical solid phantom  

International Nuclear Information System (INIS)

International and national reports strongly recommend experimental verification of the calibration of new HDR 192Ir sources prior to their clinical application for afterloading brachytherapy. To guarantee traceability, calibrated transfer standards are used, e.g. the recommended well-type ionization chambers (WIC) or certain detector-phantom arrangements (DPA) consisting of a thimble-type ionization chamber with a solid phantom. In Germany, direct calibrations for 192Ir were only provided for WICs. In June 2010, the PTB directly calibrated a DPA-transfer standard in the quantity reference air-kerma rate (RAKR) for 192Ir photons for the University Hospital Tubingen. This direct calibration provides the advantage that the comprehensive RAKR 192Ir calibration coefficient already takes all influence quantities into account - their correction factors are thus unified - except for the air-density correction kp. The DPA-transfer standard described above and a WIC used as a reference were compared for acceptance tests of three GammaMedplus HDR 192Ir afterloading sources. The measurement uncertainty of the WIC and of the DPA-transfer standard were ±2.6% (k = 2) and ±2.8% (k = 2) respectively. A strong correlation was found between these measurement results with a coefficient of determination of r2 = 0.9998. Determining the RAKR of an HDR 192Ir afterloading source is as simple with the DPAloading source is as simple with the DPA as it is with WIC. The direct 192Ir calibrated DPA-transfer standard can therefore be used alternatively in future with the same measurement uncertainty if no WIC is available. (authors)

152

Comparison of the air-kerma standards of the PTB 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 Physikalisch-Technische Bundesanstalt (PTB), Germany, and the Bureau International des Poids et Mesures (BIPM) in the x-ray range from 10 kV to 50 kV. Additional measurements were made at 80 kV and 100 kV to provide information on the electron-loss correction for the BIPM standard at these qualities. The comparison took place at the BIPM in March 1999 using the reference conditions recommended by the CCRI. There is general agreement at the level of one standard uncertainty, although there is a significant trend in the results between 30 kV and 50 kVa. This is in part due to the treatment of fluorescence radiation. The effect of fluorescence for the BIPM standard has been calculated using the Monte Carlo code EGSnrc and the fluorescence correction calculated in this way and the effect of including these new values in the present comparison are given. It should be noted, however, that these new correction factors for the BIPM standard have not yet been adopted. The result at 10 kV is significantly different from the others. This is not uncommon and raises a number of possibilities, for example the large corrections for air attenuation and guard wire attenuation, or unexplained aperture effects that have arisen in certain comparisons. In this respect, it is possible that the uncertainties for the 10 kV quality are underestimated. The measurements at 80 kV and 100 kV were made principally to test the correction factors for the BIPM standard, making use of the fact that the large electrode separation of the PTB PK100 chamber results in very little electron loss. (authors)

153

From reference air-kerma-rate to nominal absorbed dose-rate to water Paradigm shift in photon brachytherapy: ISO new work item proposal  

International Nuclear Information System (INIS)

Full text: Over decades, photon radiation brachytherapy (BT) has proven worldwide as an essential modality of high precision radiation oncology for certain primary tumor sites. The dosimetric uncertainty of photon brachytherapy, however, is currently much larger than in external beam radiotherapy due to several factors including: calibration to the reference air-kerma-rate K.R K.R (or air-kerma strength), dose calculation model, dosimetric functions and dose measurement complexity, besides the geometrical dose uncertainties in high dose-gradient BT-fields. In addition, many photon sources are applied with quite different dosimetric properties requiring much skill from the medical physicist. This work proposes increased accuracy of brachytherapy through improvements in source calibration and clinical dosimetry methodology. Currently, BT-photon sources are calibrated free in air, at 100 cm distance, and in terms of K.R. By calibrating BT-photon sources directly to the TG-43U1 reference point at 1 cm in water, to be named the nominal absorbed dose-rate to water, D.w,1, the number of calibration steps in the traceability chain is reduced from 6 to 4, thus reducing the expanded uncertainty in dose delivery for patient treatment. With a target combined uncertainty of ucue.w,1 primary standards, whi/sup>w,1 primary standards, which will soon become available for high energy and low energy, high and low dose-rate BT-photon sources. This is a paradigm shift that requires: international consensus, metrologic work and guidance. Thus, there is a need for an ISO standard based on and extending the AAPM TG-43U1 formalism. Taking into account the results and conclusions of the AAPM 2010 discussions, a draft for an ISO new work item proposal on Clinical dosimetry - Photon radiation sources for brachytherapy will be presented. This standardization project could be launched within ISO TC 85/SC 2/WG 22, in continuation of ISO 21439 (2009) for beta radiation sources. Clear terms and definitions are basic requirements for this standard. It is proposed that BT-photon radiation qualities need to be reclassified as: high-energy >100 keV, medium energy 40 keV to 100 keV, and low energy photons .w,1-recalibrated special transfer standards like well-type ionization-chambers) and as fast, direct reading dosemeter with high spatial and temporal resolution as required for detailed acceptance tests of BT-sources, -software, -planning, and -verification. This ISO-standard will provide guidance for clinical BT-dosimetry in terms of absorbed dose to water and for estimating the uncertainty of this new quantity. Most standardized procedures can be given by referring to AAPM-reports and ESTRO-documents. General quality assurance issues, radiation protection and safety issues are outside the scope. Recommendations will be prepared to replace the K.R K.R by D.w,1 as basic dosimetric quantity, to become consistent with external beam radiotherapy and to reduce the dosimetric uncertainty in brachytherapy

154

Nuclear heating constant KERMA library  

International Nuclear Information System (INIS)

Based on evaluated nuclear data file JENDL-3, published in April 1990, we produced a nuclear group constant KERMA library for fusion nuclear group constant set FUSION-J3 instead of the KERMA library for GICX40. Neutron KERMA factors were calculated directly by considering the kinematics in collisions, called 'Direct Method'. In this method, uncertainties in calculated KERMA factors are expected to be reduced since subtraction between great numbers is not necessary as in the energy balance method. Gamma ray KERMA factors were calculated by the energy balance method. In case of gamma ray, there is no problem in calculating gamma ray KERMA by the energy balance method since gamma ray heating means energy deposition of kinetic energy in gamma ray. Produced KERMA library is applicable to fusion neutronics calculations. It is expected that highly accurate results will be obtained in nuclear heating calculations for fusion reactor designs. (author)

155

Ferramenta computacional para avaliação de kerma no ar em aplicações de radioproteção em áreas de internação de pacientes: proposição de um método simples para avaliação experimental / Computational toolkit for evaluating air kerma with the purpose of radiation protection of hospital inpatients: proposal of a simple experimental evaluation method  

Scientific Electronic Library Online (English)

Full Text Available OBJETIVO: Apresentar uma ferramenta de análise de dados que pode ser utilizada para proteção de pacientes e trabalhadores em áreas de uso de equipamentos móveis. MATERIAIS E MÉTODOS: Foi desenvolvida uma ferramenta, em planilha ativa Excel®, que utiliza medidas de exposição para gerar um banco de da [...] dos de fatores de forma e calcular o kerma no ar ao entorno de um leito. O banco de dados inicial foi coletado com três equipamentos móveis. Um espalhador não antropomórfico foi utilizado, sendo realizadas medidas de exposição em uma malha de (4,2 × 4,2) m², ao passo de 0,3 m. RESULTADOS: A ferramenta calcula o kerma no ar (associado à exposição de pacientes expostos e ao equivalente de dose ambiente) à radiação secundária. Para distâncias inferiores a 60,0 cm, valores acima do limite máximo de equivalente de dose ambiente definido para área livre (0,5 mSv/ano) foram verificados. Os dados coletados a 2,1 m foram sempre inferiores a 12% do referido limite. CONCLUSÃO: A ferramenta é capaz de auxiliar na proteção radiológica de pacientes e trabalhadores, quando associada à coleta de dados adequada, pois possibilita a determinação de áreas livres ao entorno de leitos em áreas onde equipamentos móveis geradores de radiação X são utilizados. Abstract in english OBJECTIVE: To present a data analysis toolkit that may be utilized with the purpose of radiation protection of hospital inpatients and workers in areas where mobile apparatuses are used. MATERIALS AND METHODS: An Excel® ActiveSheet was utilized to develop a computational toolkit with exposure measur [...] ements to generate a database of shape factors and to calculate the air kerma around hospital beds. The initial database included data collected with three mobile apparatuses. A non-anthropomorphic phantom was utilized and exposure measurements were performed on a (4.2 × 4.2) m² mesh-grid at 0.3 m steps. RESULTS: The toolkit calculates the air kerma (associated with patients' radiation exposure and with ambient equivalent dose) under secondary radiation. For distances lower than 60.0 cm, values above the maximum ambient equivalent dose threshold defined for radiation free areas (0.5 mSv/year) were verified. Data collected at 2.1 m have always presented values lower than 12% of that threshold. CONCLUSION: The toolkit can aid in the radiological protection of patients and workers, provided it is combined with appropriate data collection, since it allows the determination of radiation free areas around beds in rooms where mobile X-ray apparatuses are utilized.

Gabriela, Hoff; José Rodrigo Mendes, Andrade; Andréia Caroline Fischer da Silveira, Fischer; Alexandre, Bacelar.

2012-04-01

156

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 coming 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)

157

Key comparison BIPM.RI(I)-K2 of the air-kerma standards of the LNE-LNHB, France and the BIPM in low-energy x-rays  

Energy Technology Data Exchange (ETDEWEB)

A key comparison has been made between the air-kerma standards of the LNE-LNHB, France 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 of the comparison of 1.6 parts in 10{sup 3}, with no evidence of a trend in the results at different radiation qualities. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. (authors)

Burns, D.T.; Roger, P. [Bureau International des Poids et Mesures, Pavillon de Breteuil, F-92312 Sevres cedex (France); Denoziere, M.; Leroy, E. [CEA Saclay, LIST Laboratoire National Henri Becquerel, CEA Saclay, 91191 Gif sur Yvette (France)

2011-08-15

158

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)

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)

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

159

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)

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)

Rosado, Paulo Henrique Goncalves

2008-07-01

160

Air Quality Index (AQI) -- A Guide to Air Quality and Your Health  

Science.gov (United States)

... Air Quality Conditions Zip Code: State : National Summary Air Quality Index (AQI) - A Guide to Air Quality and Your Health You will ... Air Quality and Your Health (PDF, 12pp., 333KB) Air Quality Guide for Ozone Air Quality Guide for Particle Pollution ( ...

161

Report on EUROMET.RI(I)-K1 and EUROMET.RI(I)-K4 (EUROMET project no. 813): Comparison of air kerma and absorbed dose to water measurements of 60Co radiation beams for radiotherapy  

International Nuclear Information System (INIS)

The results of an unprecedented international effort involving 26 countries are reported. The EUROMET.RI(I)-K1 and EUROMET.RI(I)-K4 key comparisons were conducted with the goal of supporting the relevant calibration and measurement capabilities (CMC) planned for publication by the participant laboratories. The measured quantities were the air kerma (Kair) and the absorbed dose to water (Dw) in 60Co radiotherapy beams. The comparison was conducted by the pilot laboratory MKEH (Hungary), in a star-shaped arrangement from January 2005 to December 2008. The calibration coefficients of four transfer ionization chambers were measured using two electrometers. The largest deviation between any two calibration coefficients for the four chambers in terms of air kerma and absorbed dose to water was 2.7% and 3.3% respectively. An analysis of the participant uncertainty budgets enabled the calculation of degrees of equivalence (DoE), in terms of the deviations of the results and their associated uncertainties. As a result of this EUROMET project 813 comparison, the BIPM key comparison database (KCDB) will include eleven new Kair and fourteen new Dw DoE values of European secondary standard dosimetry laboratories (SSDLs), and the KCDB will be updated with the new DoE values of the other participant laboratories. The pair-wise degrees of equivalence of participants were also calculated. In addition to assessing calibration techniques and uncertainty ng calibration techniques and uncertainty calculations of the participants, these comparisons enabled the experimental determinations of NDw/NKair ratios in the 60Co gamma radiation beam for the four radiotherapy transfer chambers. (authors)

162

The influence of micro location on the air freezing index  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper are exposed research results of air freezing index values occurring in area of Bosnia and Herzegovina. Theoretic probabilities of air freezing index occurrence are calculated, based on data of 26 meteorological stations, in order to determine its return periods of appearing (the probability of air freezing index appearance average once in period considered. To this purpose five the most frequent in praxis theoretic distribution functions are used: GAUSS, GALTON, LOG-PEARSON, PEARSON and GUMBEL. As the most appropriate function for all meteorogic stations the LOG-PEARSON was selected because it on the best way approximates values of calculated air freezing index. Regarding to influence of micro location on the value of air freezing index some independent parameters of location which are measurable (variables and have supposed influence, are took in analysis. To this purpose the mathematic model of multi variant regression analysis was used and the regression equation of the associated influence of independent parameters was determined. Using this discovered equation designers of road pavement can for each micro-location cutted by the road line, calculate the air freezing index and check the pavement structure on the harmful freezing effects.

Mazi? Branko

2004-01-01

163

Remarks on KERMA Factors in ACE files  

Science.gov (United States)

Some neutron KERMA factors in ACE files are negative and extremely large if nuclear data libraries do not keep energy-balance. The status of neutron KERMA factors in the official ACE file of ENDF/B-VII.1 is examined. As a result, it is found out that neutron KERMA factors of nuclei more than 200 in ENDF/B-VII.1 have some problems. Effects of the inadequate KERMA factor are also investigated, which are large for neutron heat while those are small for total (neutron + gamma) heat. Users who use only neutron KERMA factors should check if the factors are adequate or not before they use the factors.

Konno, C.; Ochiai, K.; Takakura, K.; Sato, S.

2014-04-01

164

X Ray Spectrometry of Low Energy Photons for Determining Conversion Coefficients from Air Kerma, Ka, to Personal Dose Equivalent, Hp(10), for Radiation Qualities of the ISO Narrow Spectrum Series  

International Nuclear Information System (INIS)

The pulse height spectra of the radiation qualities N-10 to N-120 of the ISO narrow spectrum series (N) were measured using a commercial Ge spectrometer and a specially designed lead collimator. For the unfolding of these spectra, three response matrices of the Ge spectrometer for different maximum energies and energy resolutions were calculated by the EGS4 (Electron Gamma Shower version 4) code incorporating the PRESTA and LSCAT options. Then, the pulse height spectra were unfolded with two different algorithms to check the correctness. To verify the measuring and unfolding method, the first half value layers (HVLs) were determined using small ionisation chambers and the fluence spectra. The mean photon energies were calculated, also on the basis of the fluence spectra, and compared with published values. For each radiation quality N-10 to N-120 the conversion coefficients hpK(10;N,?) from air kerma Ka to personal dose equivalent at 10mm depth, Hp (10,?), were calculated for angles of incidence ? of 15, 30, 45, 60 deg. and 75 deg. between the unidirectional photon field and the normal to the slab phantom surface. Because the fluence spectra were influenced by the air density, in particular the low energy spectra, the hpK(10;N,?) values were normalised to reference conditions. Differences of up to about 88% between the hpK(10;N,?) values presented in this work and those given in ISO/FDIS 4037-3 were found. (aven in ISO/FDIS 4037-3 were found. (author)

165

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  

Science.gov (United States)

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. 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).

Tanaka, T.; Saito, N.; Bero, M.; Butler, D.; Mahant, A. K.; Meghzifene, A.; Chu, C. H.; Kadni, T. B.; Jinjie, WU; Soodprasert, T.

2014-01-01

166

An updated equation for the refractive index of air  

Science.gov (United States)

Laser has been widely used in spectroscopic and metrological measurement. High-precision laser metrology is affected by the refractive index of air. In order to apply the algorithm for the refractive index of air in some situation where low calculation complexity and high-precision are needed, the algorithm of the refractive index of Rueger is updated. As the errors of Rueger's algorithm are mainly affected by temperature, humidity, and the concentration of carbon dioxide in the atmosphere as well as laser wavelength, we do some revisions about these effects of the factors of atmosphere in Rueger's algorithm. The conditions of standard air is redefined in this paper because of the average concentration of carbon dioxide in the atmosphere has been changed in the past few decades. As the concentration of carbon dioxide in the air is not constant, the effect of carbon dioxide on the refractive index of air is taken into consideration in the updated algorithm. The updated algorithm adapts to the real atmosphere well. The effects of dry air and humid air on the algorithm are also corrected, and the refractive index of air calculated by the updated algorithm is much closer to that of Philip E.Ciddor's algorithm defined as reference algorithm in the paper because of its high-precision. The performance of the updated algorithm is also analyzed in this paper. It is compared to that of the reference algorithm and the real measured data. Comparing results show that the performance of the algorithm has been improved after the correction. Comparing to the reference algorithm, the performance of the updated algorithm is a little bit lower, but the updated algorithm is much simpler and easier to be applied. Comparing to Rueger's algorithm, the performance of the updated algorithm is much higher and the complexity of the updated algorithm increases very small. The updated algorithm meets low calculation complexity and high-precision requirements.

Li, Wenchen; Dai, Zuoxiao; Dai, Ning; Chen, Ren; Sun, Xiaojie; Xia, Xiang; Li, Tao; Ma, Bei; Sheng, Hao

2014-12-01

167

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)

168

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

169

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)

170

Hold Your Breath. A New Index of Air Quality  

Energy Technology Data Exchange (ETDEWEB)

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.

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

171

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.

172

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

173

Forecasting of daily air quality index in Delhi.  

Science.gov (United States)

As the impact of air pollutants on human health through ambient air address much attention in recent years, the air quality forecasting in terms of air pollution parameters becomes an important topic in environmental science. The Air Quality Index (AQI) can be estimated through a formula, based on comprehensive assessment of concentration of air pollutants, which can be used by government agencies to characterize the status of air quality at a given location. The present study aims to develop forecasting model for predicting daily AQI, which can be used as a basis of decision making processes. Firstly, the AQI has been estimated through a method used by US Environmental Protection Agency (USEPA) for different criteria pollutants as Respirable Suspended Particulate Matter (RSPM), Sulfur dioxide (SO2), Nitrogen dioxide (NO2) and Suspended Particulate Matter (SPM). However, the sub-index and breakpoint concentrations in the formula are made according to Indian National Ambient Air Quality Standard. Secondly, the daily AQI for each season is forecasted through three statistical models namely time series auto regressive integrated moving average (ARIMA) (model 1), principal component regression (PCR) (model 2) and combination of both (model 3) in Delhi. The performance of all three models are evaluated with the help of observed concentrations of pollutants, which reflects that model 3 agrees well with observed values, as compared to the values of model 1 and model 2. The same is supported by the statistical parameters also. The significance of meteorological parameters of model 3 has been assessed through principal component analysis (PCA), which indicates that daily rainfall, station level pressure, daily mean temperature, wind direction index are maximum explained in summer, monsoon, post-monsoon and winter respectively. Further, the variation of AQI during the weekends (holidays) and weekdays are found negligible. Therefore all the days of week are accounted same in the models. PMID:21962560

Kumar, Anikender; Goyal, P

2011-11-15

174

Comparison of the air-kerma standards of the VNIIM and the BIPM in the low-energy X-ray range  

International Nuclear Information System (INIS)

An indirect comparison has been made between the air erma standards of the VNIIM and the BIPM in the low-energy x-ray range. The results show the standards to be in agreement at the level of one to two standard uncertainties. The trend in the results at different radiation qualities is explained in terms of the photon-scatter correction applied to the VNIIM standard. (authors)

175

Determination of backscatter factors for diagnostic x-ray beams by experimental and Monte Carlo Methods and determination of air kerma to dose equivalent conversion factors for the calibration of personal monitors  

International Nuclear Information System (INIS)

Backscatter measurements are essential for the determination of the Dose Equivalent quantity H(0.07) in phantoms or H'(0.07) in ICRU sphere, both for area monitoring and individual monitoring purposes. Backscatter factor data for the diagnostic x-ray beams are sparsely Some of the published data are entirely from calculations for idealised irradiation conditions available. A Siemens Polymat 501 diagnostic x-ray machine was used for the investigations. Variations in kV, mA and time of exposure of the machine are microprocessor-controlled, giving a highly stable output. A light beam diaphragm was attached to the x-ray tube and the total inherent filtration was estimated as 2.9 mm Al. The spectra in terms of exposure per keV interval as well as Photon fluence per keV interval of the three collimated reference beams of 40 kV, 60 kV, 81 kV were determined by attenuation analysis method, using a free air chamber and pure aluminium and copper attenuators. A 3 c.c. spherical Shonka C-552 chamber and a 0.2 c.c. Nuclear Enterprises type 2577 graphite walled chamber which were calibrated against low kV primary standard free air chamber were used to determine back scatter factors for PMMA and water phantom respectively. The measuring set-up consisted of locally designed Varactor input operational amplifier in conjunction with a Philips digital voltmeter and 1 nano Farad reference capacitance. Back scatter factors were determined using 30 cm x 30 cm x 15 cm PMMA phantom and a 30 ccm x 30 cm x 15 cm PMMA phantom and a 30 cm x 30 cm x 25.6 cm reference water phantom and conversion coefficients in terms of H(0.07)/Air kerma were determined, which can be used to calibrate personal monitors. The Monte Carlo Code for Neutrons and Photons (MCNP) was also used to find out the Back scatter factors and back scattered spectra for the PMMA and water phantom. The paper gives the details of the experiment and results and comparisons with published data. Typical Results: The ratio of measured to Monte Carlo determined backscatter values were with ±3% at the three beams used. The Monte Carlo values showed an agreement of better than ±6% with Physikalische Technische Bundesanstat (PTB) Monte Carlo values of nearest narrow spectra. (author)

176

Refractive Index of Humid Air in the Infrared: Model Fits  

CERN Document Server

The theory of summation of electromagnetic line transitions is used to tabulate the Taylor expansion of the refractive index of humid air over the basic independent parameters (temperature, pressure, humidity, wavelength) in five separate infrared regions from the H to the Q band at a fixed percentage of Carbon Dioxide. These are least-squares fits to raw, highly resolved spectra for a set of temperatures from 10 to 25 C, a set of pressures from 500 to 1023 hPa, and a set of relative humidities from 5 to 60%. These choices reflect the prospective application to characterize ambient air at mountain altitudes of astronomical telescopes.

Mathar, R J

2006-01-01

177

Secondary charged particle spectra and kerma calculations  

International Nuclear Information System (INIS)

The calculation of kerma factors from known cross sections is not as simple as is often implied. The kerma factors are strongly influenced by the reaction mechanism assumed. An important example of this dependence on the reaction mechanism is the contribution of the 12C(n,n')3? reaction to the total kerma in carbon. First, a short review will be given of the ENDF/B-V carbon cross sections which were used in the calculation of carbon kerma factors. Using the reaction channels implied in the ENDF/B-V evaluation, the contribution of various reactions to the total kerma factors in carbon will be given. A detailed analysis of the reaction mechanisms which could contribute to the (n,n')3? reaction in carbon has been carried out. First their contribution to kerma, independent of cross section, will be calculated and then the initial spectra of alpha particles produced by the various reaction mechanisms will be given. A discussion of possible ways of experimentally distinguishing the reaction mechanisms will be made by comparing their different initial spectra and their variation in kerma with neutron energy. Finally, the event-size spectra for tissue-equivalent proportional counters will be presented, giving only the contributions from the (n,n')3? reaction and its various possible reaction channels. 3 refs., 11 figs., 4 tabs

178

Seasonal ARIMA for Forecasting Air Pollution Index: A Case Study  

Directory of Open Access Journals (Sweden)

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.

Muhammad H. Lee

2012-01-01

179

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

180

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

181

SELFAS2 : radio emission from cosmic ray air showers. Effect of realistic air refractive index  

CERN Document Server

Using the simulation code SELFAS2, we present predictions of the radio signal emitted by extensive air showers (EAS) during their development in the atmosphere. The radio emission in the MHz range coming from air showers is the superposition of two mechanisms: the variation of the transverse current due to the systematic opposite drift of electrons and positrons in the Earth's magnetic field and the variation of the charge excess due to the electrons in excess in the shower front. In this paper, we stress particularly the effect of the realistic air refractive index on the radio signal predicted by SELFAS2.

Marin, Vincent

2012-01-01

182

Evaluation of reference kerma rate determination procedures applied to 192Ir sealed radionuclide sources by radiotherapy departments in the Czech Republic  

International Nuclear Information System (INIS)

Reference air kerma rates of 192Ir sealed high-dose rate sources determined by the National Radiation Protection Institute within independent audits of carried brachytherapy departments in the Czech Republic were compared with the data in the sealed radionuclide source certificates and status test reports. The reference air kerma rates were measured by the free in-air technique. Furthermore, the reference air kerma rate determination procedures applied during independent audits and during radiation source acceptance procedures and status tests are mutually compared. Particular attention is paid to the determination of the 192Ir calibration factor and to the use of correction factors. Recommendations are given for a correct determination of the reference air kerma rates. (orig.)

183

The quotient of absorbed dose and the collision part of kerma for photon beams  

International Nuclear Information System (INIS)

With the conceptual definition of the quotient (?) of absorbed dose and the collision part of kerma for photon beams, the procedure of computing ? is briefly described. A series of calculations of ? was carried out for photons of 0.4, 0.5, 1 and 2 MeV in polystyrene, carbon, air and aluminium. Resultant values are tabulated and evaluated. (author)

184

Índice integrado de calidad del aire para ciudades colombianas / Integrated air quality index for Colombian cities  

Scientific Electronic Library Online (English)

Full Text Available SciELO Colombia | Language: Spanish Abstract in spanish En este trabajo se propone un índice que integra información sobre los dos contaminantes criterio de mayor incidencia sobre la salud humana en las ciudades colombianas, ozono (O3) y material particulado con diámetro menor a 10?m (PM10), utilizando lógica difusa. El índice se calcula para las normas [...] de calidad del aire que rigen actualmente en Colombia, aunque su adaptación a otras reglamentaciones es sencilla. Abstract in english In this work an integrated index is proposed using fuzzy logic which incorporates information on the two criteria pollutants of highest incidence on human health in Colombian cities, ozone (O3) and particulate matter with diameter less than 10?m (PM10). The index is calculated for current Colombian [...] air quality standards, although its adaptation to others is straightforward.

Mauricio, Jaramillo; Daniel Enrique, González; María Eugenia, Núñez; Gloria, Portilla.

2009-06-01

185

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)

186

Neutron and gamma kerma and spectrum measurements to 1.6 km from a neutron source  

International Nuclear Information System (INIS)

The Army Pulse Radiation Division at Aberdeen Proving Ground operates a neutron source which provides U235 fission neutrons and gamma rays in an air-over-ground geometry. Neutron and gamma tissue kerma and spectra have been measured out to a range of 1.6 km from the source. These data are used to validate various analytical radiation transport and shielding models, including those used in Hiroshima-Nagasaki dose reevaluation efforts. (author)

187

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)

188

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

Czech Academy of Sciences Publication Activity Database

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

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

189

Comparing air quality among Italy, Germany and Poland using BC indexes  

OpenAIRE

In this paper we discuss air quality assessment in three Italian, German and Polish regions using the index methodology proposed in Bruno and Cocchi (2002, 2007). This analysis focuses first of all on the quality of the air in each of the countries being taken into consideration, and then adopts a more general approach in order to compare pollution severity and toxicity. This is interesting in a global European perspective where all countries are commonly involved in assessing air quality and...

Bodnar, Olha; Cameletti, Michela; Fasso, Alessandro; Schmid, Wolfgang

2008-01-01

190

Working with 150-MeV evaluations: NJOY and KERMA  

International Nuclear Information System (INIS)

New evaluations of neutron and proton data to 150 MeV will allow the accurate determination of radiation heating for several important applications including accelerator technologies and radiation therapy. The NJOY Nuclear Data Processing System has been extended to convert these data into kerma factors for easy calculations of neutron heating. The results compare well with experimental kerma measurements

191

Tsp and Pm10 Measurement and Description of Air Quality Index (Aqi in the Ambient Air in Shariati Hospital District  

Directory of Open Access Journals (Sweden)

Full Text Available Apparently, breathing clean air is of significant importance to human beings and thus attention to what enters our body through inhalation is on the increase. Tehran’s air pollution has received considerable media coverage in recent years: Since particulate matter (TSP and PM10 is one of the important pollutants in this city, an attempt was made to study TSP and PM10 concentrations and to make a qualitative assessment of air using the Air Quality Index (AQI, with TSP and PM10 sampling both daily and on a monthly basis. Shariati Hospital district was selected as study area from 22 December 2001 to 20 April 2002. To determine the amount of TSP and PM10 according to EPA and WHO standards, 61 samples were taken for TSP and 61 samples for PM10 with High Volume Sampler. The results indicated that: •As for TSP and PM10, the period extending from 20 February to 20 March (Esfand was the most heavily polluted one in this study. The cleanest spell was observed from 21 March to 20 April (Farvardin. •Saturdays and Mondays were the most polluted days of the week for TSP and PM10 and Fridays were the cleanest. •As for TSP, In 51 percent of the samples the Air Quality Index (AQI was below 100 (AQI100. •In the case of PM10, in 75.5 percent of samples the Air Quality Index (AQI was below 100 (AQI100.

A.S Mesbah

2004-06-01

192

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

193

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

Science.gov (United States)

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 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. PMID:22086025

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

2011-11-01

194

An international calibration of Kerma - Area Product meters for patient dose optimisation study  

International Nuclear Information System (INIS)

The results of international calibration of Kerma Area Product (KAP) meters for European SENTINEL survey on patient dose optimisation of cardiac and interventional radiology practice are presented. Twelve countries were involved in the study. An investigation was conduced on 25 KAP meters fitted to under-couch X-ray tubes; 13 KAP meters were installed on cardiac units and the remaining 12 on interventional ones. The simplified calibration method has been applied, consisting of KAP estimation by multiplying the air kerma at the centre of the X-ray field by the irradiated area. The obtained values of calibration factors range from 0.4 to 0.9 and from 0.4 to 0.8 for KAP meters installed on cardiac and interventional units, respectively. They account also for table and mattress attenuation. For air kerma assessment, measurements with thermoluminescent dosemeters have been applied and when possible compared against an additional reference dosemeter. As the result of the investigation, the importance of calibration of KAP meters in clinical conditions that include mattress and table attenuation has been recognised. (authors)

195

PROFILE: The Use of a Simple Air Quality Index in the Helsinki Area, Finland  

Science.gov (United States)

/ A simple air quality index (AQI) was introduced for the Helsinki Metropolitan Area in 1993, in order to inform the public about the current air quality in an easily understood way. The pollutants included in the AQI are CO (1 and 8 h), NO2 (1 and 24 h), SO2 (1 and 24 h), O3 (1 h) and PM10 (24 h). The AQI is linked to the new air quality guidelines in Finland. The AQI is based on acute health effects, but long-term effects on nature and materials are also taken into consideration. Subindices are calculated hourly for all pollutants and for a given hour the highest subindex becomes the AQI. AQI values are currently calculated for the center of Helsinki and for typical suburban areas.KEY WORDS: Air pollution; Air quality index; Guidelines; Helsinki; Finland PMID:9582388

Hämekoski

1998-07-01

196

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

Science.gov (United States)

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

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

2015-04-01

197

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 particior 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

198

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 Memoerage (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)

199

VEHICLE TO VEHICLE COMMUNICATION FOR SHARING AIR QULAITY INDEX USING RFID ALONG WITH GPS AND WAP???????  

Directory of Open Access Journals (Sweden)

Full Text Available This paper studies the vehicle to vehicle communication to share Air Quality Index messages. .AQI Indicates whether pollutant levels in air may cause health concerns. AQI Ranges from 0 (least concern to 500 (greatest concern. This air quality message is passed by communication like one-to-many, local, and geo-significant. The vehicular communication network is ad-hoc, highly mobile, and with large numbers of contending nodes. We design several random access protocols for medium access control. The protocols fit in the facility of RFID, GPS and WA P

N.Vallileka

2015-03-01

200

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...

201

ZZ VITAMIN-J/KERMA, Gas Production Cross-Sections, Neutron and Gamma Kerma in FOURACES Format  

International Nuclear Information System (INIS)

1 - Description of program or function: Format: ANISN; Number of groups: 175 neutron plus 38 photon energy groups; Nuclides: H-1, D-2, T-3, Li-6, Li-7, Be-9, B-10, B-11, C, O-16, Al-27, Si, Ti, V, Cr, Mn-55, Fe, Ni, Cu, Zr, Nb-93, Mo, Ba-134, Ba-135, Ba-136, Ba-137, Ba-138, W-182, W-183, W-184, W-186, Pb, Bi-209, He-3, He-4, N-14, Mg, P-31, S, Ca, Co-59, In, Sn, Ta-181, Re Origin: EFF-1, DLC-99 (HUGO) data library; Weighting spectrum: Maxwellian plus 1/E plus fission spectrum plus fusion peak. Library of gas production cross sections, neutron kerma factors and photon kerma factors in FOURACES format according to GEFF-1 specifications. Kerma factors have been calculated for temperatures 300 K and 800 K. 2 - Method of solution: For the gas production cross sections, the lump reactions 203 and 207 included in EFF-1 had been assumed as the basic of the computation. The neutronics kerma factors have been calculated with the module KERMA of THEMIS. The photonic kerma factors have been calculated with the module GROUPG of THEMIS, starting from the DLC-99 (HUGO) data library of gamma interactions

202

Measurement and calculation of fluence, spectra and tissue kerma at large distances from a fission source  

International Nuclear Information System (INIS)

An experimental program is underway at the Army Pulse Radiation Division reactor (APRDR) at Aberdeen Proving Ground, Maryland, to provide benchmark quality radiation transport data characterizing an air-over-ground environment. The data are used to evaluate analytical radiation transport models and provide validation for techniques used to measure radiation protection or shielding of various materiel. The APRDR is a bare critical assembly fueled with uranium ten weight percent molybdenum alloy. For this application the reactor is operated outdoors 14M above ground. Todate measurements have been made by both US and German scientists of neutron and gamma fluence, spectra, and kerma at ranges from 1 to 400 meters from the reactor

203

Procedures for establishing and maintaining consistent air-kerma strength standards for low-energy, photon-emitting brachytherapy sources: Recommendations of the Calibration Laboratory Accreditation Subcommittee of the American Association of Physicists in Medicine  

International Nuclear Information System (INIS)

Low dose rate brachytherapy is being used extensively for the treatment of prostate cancer. As of September 2003, there are a total of thirteen 125I and seven 103Pd sources that have calibrations from the National Institute of Standards and Technology (NIST) and the Accredited Dosimetry Calibration Laboratories (ADCLs) of the American Association of Physicists in Medicine (AAPM). The dosimetry standards for these sources are traceable to the NIST wide-angle free-air chamber. Procedures have been developed by the AAPM Calibration Laboratory Accreditation Subcommittee to standardize quality assurance and calibration, and to maintain the dosimetric traceability of these sources to ensure accurate clinical dosimetry. A description of these procedures is provided to the clinical users for traceability purposes as well as to provide guidance to the manufacturers of brachytherapy sources and ADCLs with regard to these procedures

204

Refractive index sensing with an air-slot photonic crystal nanocavity  

OpenAIRE

We investigate an air-slot photonic crystal cavity for high-precision refractive index sensing. The high quality factor ?2:6 × 10^4 of the cavity, along with a strong overlap between the resonant mode and the hollow core region, allows us to achieve an experimental sensitivity of 510 nm per refractive index unit (RUI) and a detection limit below 1 × 10^?5 RUI. The device has a remarkably low sensing volume of 40 aliters, holding less than 1 × 10^6 molecules.

Ja?gerska?, Jana; Zhang, Hua; Diao, Zhaolu; Le Thomas, Nicolas; Houdre?, Romuald

2010-01-01

205

Simultaneous measurements of radar reflectivity and refractive index spectra in clear air convection.  

Science.gov (United States)

Simultaneous measurements of radar reflectivity and radio refractive index at several altitudes in clear air convection have been made. The experimental data were compared with the theoretical relationship which relates the reflectivity to the refractivity spectrum. The agreement between the measurements and the theory is excellent and shows that the radar returns in clear air are the result of, and can be quantitatively described as being from, fine-scale refractivity fluctuations due to turbulent mixing. Further, the data give strong support to the -5/3 spectral decay of the refractivity spectrum in the inertial subrange.

Konrad, T. G.; Robison, F. L.

1972-01-01

206

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

OpenAIRE

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...

Hanif SedighNejad; Tariq Iqbal; John Quaicoe

2014-01-01

207

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

Directory of Open Access Journals (Sweden)

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.

SULISTIJORINI

2008-09-01

208

Effect of the relative optical air mass and the clearness index on solar erythemal UV irradiance.  

Science.gov (United States)

This paper analyses the effects of the clearness index (Kt) and the relative optical air mass (mr) on erythemal UV irradiance (UVER). The UVER measurements were made in Valencia (Spain) from 6:00 am to 6:00 pm between June 2003 and December 2012 and (140,000 data points). Firstly, two models were used to calculate values for the erythemal ultraviolet irradiance clearness index (KtUVER) as a function of the global irradiance clearness index (Kt). Secondly, a potential regression model to measure the KtUVER as a function of the relative optical air mass was studied. The coefficients of this regression were evaluated for clear and cloudy days, as well as for days with high and low ozone levels. Thirdly, an analysis was made of the relationship between the two effects in the experimental database, with it being found that the highest degree of agreement, or the joint highest frequencies, are located in the optical mass range mr?[1.0, 1.2] and the clearness index range of Kt?[0.8, 1.0]. This is useful for establishing the ranges of parameters where models are more efficient. Simple equations have been tested that can provide additional information for the engineering projects concerning thermal installations. Fourthly, a high dispersion of radiation data was observed for intermediate values of the clearness for UV and UVER. PMID:24911276

Moreno, J C; Serrano, M A; Cañada, J; Gurrea, G; Utrillas, M P

2014-09-01

209

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

Energy Technology Data Exchange (ETDEWEB)

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)

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

210

Air quality trends and potential health effects - Development of an aggregate risk index  

Science.gov (United States)

The "Provence Alpes Côte d'Azur" (PACA) region, in the South East of France, is one of Europe's regions most influenced by the atmospheric pollution. During the last 15 years, the industrial emissions decrease caused an evolution of the atmospheric pollution nature. Nowadays, atmospheric pollution is more and more influenced by the road traffic, the dominating pollution source in urban zones for the PACA region. Combined with this intense road traffic, the strong hot season of the Mediterranean climate contributes to the region bad air quality; it is known to be one of the worse in Europe. The recognized air pollution effects over public health include increased risk of hospital admissions and mortality by respiratory or cardiovascular diseases. The combination of these serious pollution related health hazards with senior and children vulnerabilities leads to serious sanitary concerns. Over the 1990-2005 period, we obtained, using the non-parametric Mann-Kendall test from annual mortality dataset (CépiDC), decreasing trends for Asthma (-5.00% year -1), Cardiovascular (-0.73% year -1), Ischemic (-0.69% year -1) and cerebrovascular diseases (-3.10% year -1). However, for "Other heart diseases" (+0.10% year -1) and "Respiratory" (+0.10% year -1) an increase was observed. The development of an adequate tool to understand impacts of pollution levels is of utmost importance. Different pollutants have different health endpoints, information may be lost through the use of a single index consequently, in this study we present the modified formula of air quality index, based on Cairncross's concept the Aggregate Risk Index (ARI). ARI is based on the relative risk of the well-established increased daily mortality, or morbidity, enabling an assessment of additive effects of short-term exposure to the main air pollutants: PM 2.5, PM 10, SO 2, O 3 and NO 2 in order to account for the reality of the multiple exposures impacts of chemical agents. The ARI, developed per pathology, takes into account the possible adverse effects associated with the coexistence of all pollutants. This index will enable to communicate the health risks associated, from modelled or monitored pollutant concentrations, to the general population. The second step will consist in the construction of a prediction model of this sanitary index.

Sicard, Pierre; Lesne, Olivia; Alexandre, Nicolas; Mangin, Antoine; Collomp, Rémy

2011-02-01

211

Application of frequency combs in the measurement of the refractive index of air  

International Nuclear Information System (INIS)

We report a new method in the precision measurement of the refractive index of air using a highly unbalanced Michelson interferometer with a femtosecond optical frequency comb as the light source. Standard dry air is filled into a 30 m multipass cell, serving as the long arm of the interferometer, while a short arm acts as the reference path. Both time and frequency domain interferograms are recorded to measure the refractive index of air. The deviation of our experimental results with Edlen's formula is 1.4x10-9 at 800 nm. Our experiment has a standard error of 5.2x10-9 at fixed parameters (pressure and temperature). This is achieved by putting the multipass cell into a temperature-stabilized box, and also by locking the interferometer path length with a He-Ne laser. We achieved a temperature stabilization of 0.8 mK for 25 h. This corresponds to 0.4 ?m multipass cell length change. The locking of the He-Ne interferometer enables us to achieve 7 nm path-length change outside the multipass cell. Combined with accurate measurement of temperature and pressure, we were able to achieve an accuracy of 7.7x10-9

212

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

213

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

Science.gov (United States)

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

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

2014-08-01

214

X ray beam quality specification for kerma area product meters  

International Nuclear Information System (INIS)

Full text: The kerma area product (KAP) in a diagnostic X ray beam is usually measured with a plane parallel transmission ionization chamber. The response of KAP chambers depend significantly on the energy distribution of radiation, and KAP meters are commonly calibrated with a discrete set of radiation qualities. Appropriate specification of radiation quality is needed to allow interpolation between the measured calibration coefficients. This is especially evident when calibration coefficients for laboratory radiation qualities are converted to clinical qualities. Radiation quality of an X ray beam can be specified explicitly by the tube voltage and total filtration, together with anode angle and material. The half value layer (HVL) of the X ray beam is a generally used beam quality specifier and depends on all these parameters. When a high quality cavity ionization chamber is used properly, the response of the chamber depends on energy rather smoothly and the HVL can be used to specify radiation quality and to interpolate the calibration coefficients between radiation qualities. This is not the case with KAP chambers, however. The energy dependence of the response is affected by the materials and design of the KAP chamber. IEC standard for KAP meters sets a requirement of maximum overall uncertainty of 25% (2 SD) for the accuracy of KAP measurement, including the maximum deviation of ±8% arising from X ray tube voltage variation, in the range of 50 kV to 150 kV wittion, in the range of 50 kV to 150 kV with a 2,5 mm aluminium filtration. No requirements for the response are stated in the standard for other filtrations. ICRU recommendations for diagnostic dosimetry state a maximum overall uncertainty of 7% (2 SD) for KAP measurements. This also emphasizes the need for accurate beam quality specification. In this work the energy dependence of KAP ionization chambers was investigated using a tungsten anode X ray tube (anode angle 20 deg.) with a set of standard and clinical radiation qualities. Tube voltages of 40 kV-150 kV and filtrations from 1,3 mm to 5 mm Al, and 4 mm Al with 0,1 mm and 0,2 mm Cu were used. The HVL values ranged from 1 mm to 9 mm Al. A diaphragm providing a strictly defined radiation field was designed and the KAP measurements were performed at 5 cm distance from the diaphragm. The reference value for the kerma area product was determined as the product of air kerma measured in the field centre and the area of the field at the same distance. For a KAP meter the calibration coefficient was determined as a quotient of the reference value by the measured KAP value. Calibration coefficients were expressed relative to different beam quality specifiers: HVL, tube voltage and filtration. For any individual KAP meter the variation of calibration coefficients was in the range of 20%-30% for the used beam qualities, yet the behaviour of the response relative to radiation quality was clearly different for KAP chambers of different design. For constant HVL values the variation of calibration coefficients ranged up to 10% among typical clinical radiation qualities used in this study, and thus the HVL alone cannot specify the radiation quality adequately. At least two beam quality specifiers need to be known to describe the response of a KAP meter. For a KAP meter, it is not possible to interpolate calibration coefficients between different X ray qualities relative to the HVL alone. Adequate and convenient specifiers in practice are the tube voltage and total filtration or, if one of these parameters is not known, the HVL instead of that. To allow the interpolations, measured calibration coefficients should cover the range of all clinically used radiation qualities. This work is part of the IAEA coordinated research project for testing the implementation of the IAEA Code of Practice on Dosimetry in X ray Diagnostic Radiology. (author)

215

A method to determine the water kerma in a phantom for X-rays with energies up to 40 keV  

International Nuclear Information System (INIS)

In brachytherapy, as in any form of radiation therapy, accurate dosimetry in terms of absorbed dose to water is required. The output of brachytherapy sources has, up to now, been specified as the reference air kerma rate at 1 m distance. For this reason, the Physikalisch-Technische Bundesanstalt is developing a primary standard to determine the absorbed dose to water at the point of measurement within a water phantom. A candidate for the standard to be newly established is a water-equivalent parallel-plate ionization chamber with continuously adjustable electrode spacing, forming an extrapolation chamber in a phantom of water-equivalent material. In this work, a method is introduced to determine the absorbed dose to water with an extrapolation chamber in a phantom of water-equivalent material. Thereby, a conversion factor C(xi+1, xi) is applied to the difference of the ionization charges measured at two different plate separations xi and xi+1. In contrast to already described methods, the applied method is based on fundamental dosimetric relations without the use of a wall-less chamber approximation. It will be shown that by using the wall-less chamber approximation, a term contributing to the absorbed dose to water is overlooked. This term is given by the net energy fluence of the secondary electrons at the surface of the measuring volume. The introduced method is verified experimentally by a comparison with water kerma valtally by a comparison with water kerma values obtained from air kerma measurements free in air and applying a conversion factor to water kerma obtained by Monte Carlo (MC) calculations for the conditions of the experiment. Evidence is produced showing that the new model significantly increases the consistency of experimental and MC results. (author)

216

Investigation of Humidity Effect on the Air Refractive Index using an Optical Fiber Design  

Directory of Open Access Journals (Sweden)

Full Text Available In this study operation of an optical design based on the intensity modulation for the refractive index change has been described. The reported instrument measures the transmitted output power depending up on the medium refractive index in the light path of a fiber-to-fiber design. A liquid cell is located between the fibers in the light path and power variations for different cold and hot water levels in the cell are measured. By using a reference humidity meter the calibration curve representing the relative humidity (%RH as a function of the transmitted output power is obtained. For the hot water with the final temperature of T = 32.7C the output power range of 255.0 -313.0 nW is measured for a relative humidity change of 32.76 -41.26%. A power variation of 58 nW is noted for the 8.5% RH variation which shows the high sensitivity for the reported sensor. For the light transmitted in dry air path the output power is 516.7 nW while for the water path such power is 784.6 nW. Thus, the reported device can check the presence of the water vapor, water, or any other transparent liquid in the gap between the two axially aligned fibers. Performance of the new system is satisfactory as a refractive index monitoring mean and for the water/water vapor sensing.

H. Golnabi

2011-01-01

217

Spatial and seasonal variations of the air pollution index and a driving factors analysis in china.  

Science.gov (United States)

In this study, the daily air pollution index (API) of 110 cities based on ground monitoring was conducted on the 2011 data set from the Ministry of Environmental Protection of China. The pollutant concentrations, seasonal variations, and spatial autocorrelations were evaluated. The results show that the major principal pollutants in China are inhalable particles. In addition, the total number of clean days (API ? 50) is apparently smaller in the northern cities than in the southern cities as a result of fuel utilization and large-scale organized central heating. Seasonally, air pollution is most severe in winter and is caused by low-frequency rainfall, strong northwest winds, dry climate, and high energy consumption; this is followed by spring, which is a season of frequent sandstorms. According to spatial autocorrelation analysis, clusters with high API value agglomeration (High-High clusters) are mainly concentrated in the middle and northern parts of China, whereas clusters with low API agglomeration (Low-Low clusters) are principally concentrated in the southern parts of China due to a favorable climate and abundant rainfall. Meteorological data, including wind speed and temperature, have great impacts on API. The air quality effects of industrial structure, energy use, urban greening, and traffic congestion were also analyzed. With the ecological function of purifying the air, industries that use natural resources and urban greening could help to reduce API, whereas secondary industry and gas use, which have a positive coefficient, increase the API value. The risk of exposure to poor air quality is largest in the winter, smallest in the summer, and remains relatively unchanged in the spring and autumn. PMID:25602202

Jiang, Hong-Yue; Li, Hai-Rong; Yang, Lin-Sheng; Li, Yong-Hua; Wang, Wu-Yi; Yan, Ya-Chen

2014-11-01

218

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)

219

Review of kerma-area product and total energy incident on patients in radiography, mammography and CT  

International Nuclear Information System (INIS)

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 x 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 1/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). 1/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. (authors)

220

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

Science.gov (United States)

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

Jyothi, S Jissy; Jaya, D S

2010-05-01

221

Partial Kerma Factors for Neutron Scattering from ^16O^  

Science.gov (United States)

Success for the use of neutron for radiation therapy and other applications in radiological physics depends on the understanding of the interaction of neutron with elements in the tissue. Study of the mechanisms of energy deposition by neutron interaction with matter is very important to improve the understanding of the neutron dosimetry. Cross section data are the basic inputs for many types of calculations in radiation physics. One important quantity in some radiological applications of neutron is the kerma (kinetic energy released in material.) Differential elastic and inelastic neutron scattering from some elements of biological interests are available at energies 18 -- 26 MeV. Optical Model Potentials based on these measured cross sections may be used to calculate various quantities of interest for the neutron dosimetry at higher energies where cross section data may not be available. Kerma values for elastic and inelastic scattering of neutron from ^16O are obtained from differential cross sections.

Islam, Mohammed

2011-10-01

222

Evaluation of calibration error for applying exposure index  

International Nuclear Information System (INIS)

Exposure indicators of digital radiography systems have been termed by manufacturers individually. The International Electrotechnical Commission (IEC) provided a concept of exposure index (EI) that unified the exposure indicators in order to recognize the deviations from the intended exposure. Although the IEC determined the calibration conditions between the exposure indicator and the air kerma at the detector surface, the tolerance was described was limited concerning the beam conditions. The purpose of this study is to evaluate the calibration error regarding the geometry and the added filtrations. The relative errors of calibrations based on the IEC condition were derived using the value of exposure indicators at EI value of 200, 500 and 1000 for field size of 10 x 10 cm, 20 x 20 cm, 30 x 30 cm and 43 x 43 cm, and source-image receptor distance (SID) of 100 cm, 120 cm, 150 cm and 200 cm. The beam qualities using added filtrations of 0.5 mm Cu +2 mm Al, 0.6 mm Cu and 21 mm Al were adjusted to RQA 5. The air kerma at the detector surface over the clinical use ranged from 0.18 to 26.3 ?Gy. Consequently, the relative errors for the calibrations were less than 6% at a field size of more than 10 x 10 cm and at SID of more than 100 cm with all added filtrations. (author)

223

[Evaluation of calibration error for applying exposure index].  

Science.gov (United States)

Exposure indicators of digital radiography systems have been termed by manufacturers individually. The International Electrotechnical Commission (IEC) provided a concept of exposure index (EI) that unified the exposure indicators in order to recognize the deviations from the intended exposure. Although the IEC determined the calibration conditions between the exposure indicator and the air kerma at the detector surface, the tolerance was described was limited concerning the beam conditions. The purpose of this study is to evaluate the calibration error regarding the geometry and the added filtrations. The relative errors of calibrations based on the IEC condition were derived using the value of exposure indicators at EI value of 200, 500 and 1000 for field size of 10×10 cm, 20×20 cm, 30×30 cm and 43×43 cm, and source-image receptor distance (SID) of 100 cm, 120 cm, 150 cm and 200 cm. The beam qualities using added filtrations of 0.5 mm Cu+2 mm Al, 0.6 mm Cu and 21 mm Al were adjusted to RQA 5. The air kerma at the detector surface over the clinical use ranged from 0.18 to 26.3 µGy. Consequently, the relative errors for the calibrations were less than 6% at a field size of more than 10 × 10 cm and at SID of more than 100 cm with all added filtrations. PMID:22104235

Ariga, Eiji

2011-01-01

224

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 ?m of 7Be aerosols have been observed at locations characterized with relative low pollution, while it is concluded that in the activity size distribucluded 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.

225

The Asthma Impact Record (AIR) index: a rating scale to evaluate the quality of life of asthmatic patients in France.  

Science.gov (United States)

Asthma is a chronic disease, which affects patients' daily lives. The goal of this study was the development of a disease-specific scale to evaluate quality of life in asthmatic patients in France: The Asthma Impact Record Index (AIR Index). The study was conducted with the participation of 486 asthmatic patients using the following steps: 1) selection of dichotomous items; 2) reduction of the number of items; 3) study of reproducibility of the questionnaire; 4) weighting of items; 5) study of the reliability and validity of the final version of the AIR Index. The final version of the AIR Index contains 63 unweighted items. The items were classified into subscales representing the main dimensions of quality of life: 1) physical, which was itself split into two subscales: a) physical activities; and b) symptoms; 2) psychological; and 3) social or relational. The internal consistency, measured by Cronbach's alpha coefficients, was found to be high, for the global scale and all subscales (range 0.79-0.94). The concurrent validity, evaluated by studying the relationship between the score values on the global scale and the subscales, and the parameters reflecting disease severity, was also high. We conclude that the AIR Index might represent a useful evaluative and discriminant instrument in studying quality of life in asthma in French populations. PMID:8804933

Letrait, M; Lurie, A; Bean, K; Mesbah, M; Venot, A; Strauch, G; Grandordy, B M; Chwalow, J

1996-06-01

226

Indexed  

CERN Document Server

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.

Hagy, Jessica

2008-01-01

227

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

Science.gov (United States)

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

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

2009-07-01

228

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

Science.gov (United States)

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.

Bekhet, Hussain A.; >Tahira Yasmin,

2013-06-01

229

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.

230

Instructor's Index to U.S. Navy and Air Force Materials for Teaching Basic Electricity. Final Report, No. 29.  

Science.gov (United States)

The purpose of this index is to identify U.S. Navy and U.S. Air Force transparencies, films, and manuals which can be used by schools and colleges to teach basic electricity. Materials are classified according to 39 major categories including Electron Theory, Batteries and Battery Connections, D.C. Series Circuits, Network Theorems,…

Stoller, Alan

231

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 and 2-900 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 gn of this stations are discriminated

232

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 researcications 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

233

Automated foam index test: Quantifying air entraining agent addition and interactions with fly ash-cement admixtures  

Energy Technology Data Exchange (ETDEWEB)

The use of a new automated foam index test (AFIT) instrument is discussed as a quantitative approach to observe air entraining agent (AEA) interactions with and to measure proper AEA dosage into cement-fly ash mixtures. Based on measuring acoustic emission from bubbles bursting on top of and in water-cement-ash mixtures after AEA addition, AFIT uses computer control to automate steps taken and quantities used during foam index testing, including: water addition; AEA titration; admixture agitation; and acoustic emission data acquisition. Variation of these steps is investigated relative to determining the dynamics of AEA adsorption onto the solid surfaces within water-cement-ash mixtures. Working within time durations needed for AEA equilibration, different water dilution and titration levels of AEA helped elucidate influences of equilibration on the AFIT-determined foam index values. A mathematical discussion about AFIT foam index curves is offered that relates changes in foam stability to surface tension and interactions with free calcia as AEA's are titrated into ash and cement-ash mixtures. Correlations between experimental surface tension data and the foam index curves are also presented. The potential of applying the AFIT to control air content in concrete with and without fly ash is also examined relative to using the C231 ASTM testing procedure on concrete mixes.

Stencel, J.M.; Song, H.P.; Cangialosi, F. [Tribo Flow Separation, Lexington, KY (United States)

2009-04-15

234

Development of a Quality Index Method (QIM) for Maatjes Herring Stored in Air and Under Modified Atmosphere  

OpenAIRE

The aim of the study was to develop a Quality Index Method (QIM) scheme for maatjes herring stored in air and under a modified atmosphere at 4°C and 10°C. The attributes included in this new scheme are: appearance of skin side and bone side, color of the blood, odor (rancidity and other), taste (rancidity and other), aftertaste and texture. The QIM scheme developed proved to be potentially useful in evaluating and defining the quality of maatjes herring stored in air and under modified atmo...

Lyhs, U.; Schelvis-smit, A. A. M.

2005-01-01

235

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

Czech Academy of Sciences Publication Activity Database

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

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

236

Assessment of skin entrance kerma in the United States: the Nationwide Evaluation of X Ray Trends (NEXT)  

International Nuclear Information System (INIS)

The Nationwide Evaluation of X ray Trends (NEXT) is an annual survey programme to estimate national skin entrance air kerma, free-in-air, for representative diagnostic X ray examinations, conducted in the United States between the federal government's Food and Drug Administration (FDA) and various state and local governments through the coordinating agency, the conference of Radiation Control Program Directors (CRCPD). NEXT began in 1973 and in 1983 underwent a major change; limiting the annual survey to one examination, using standard attenuation phantoms for the measurement of exposure, empirically evaluating film processing, and the collection of comprehensive technical data such as tube potential, half-value layer (HVL), type of film, screen, grid, and optical density of the resulting phantom radiograph. Surveys have been performed for chest radiography (1984 and 1986), abdomen and lumbosacral spine (1987 and 1989), mammography (1985 and 1988), computerised tomography (CT) (1990), and fluoroscopy (1991). (author)

237

TE and TM guided modes in an air waveguide with negative-index-material cladding.  

Science.gov (United States)

We numerically demonstrate that a planar waveguide in which the inner layer is a gas with refractive index n0 = 1, sandwiched between two identical semi-infinite layers of a negative index material, can support both transverse electric and transverse magnetic guided modes with low losses. Recent developments in the design of metamaterials with an effective negative index suggest that this waveguide could operate in the infrared region of the spectrum. PMID:15903802

D'Aguanno, G; Mattiucci, N; Scalora, M; Bloemer, M J

2005-04-01

238

Kerma factors of elements and compounds for neutron energies below 30 MeV  

International Nuclear Information System (INIS)

Based on recently calculated tables of neutron kerma factors for 19 elements, kerma factors for 44 compounds have been calculated. The neutron energy range covered extends from 8 eV to 30 MeV. Because of the increased uncertainty in the nuclear data at the higher energies, care must be taken when the tables are applied above 15 MeV. The user must also be careful when applying these results to compounds at low neutron energies, because of the difficulties in associating kerma values with molecular materials at energies below approximately 30 eV. (author)

239

Partial kerma factor data for nitrogen and oxygen for fast neutrons  

International Nuclear Information System (INIS)

The kerma for fast neutrons consists of partial kerma contributions from events such as (n,n), (n,n'), (n,p), (n,alpha) and other (n, charged particle) reactions. Improved fast neutron partial kerma values for (n,p) and (m,alpha) events for nitrogen and oxygen are evaluated using the available data on the break up of (n,p) and (n, alpha) cross sections corresponding to the ground and the various excited states of the residual nucleus in each of these two reactions. (author)

240

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

Energy Technology Data Exchange (ETDEWEB)

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.

NONE

2005-05-15

241

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

OpenAIRE

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 ...

Teyssier, Narjesse

2012-01-01

242

Experimental determination of kerma factors at E/sub n/ approx. = 15 MeV  

Energy Technology Data Exchange (ETDEWEB)

Experimental values for the kerma per unit fluence at the neutron energy, E/sub n/ = 15 MeV, have been determined for graphite, Mg, and Fe. Ion chambers of small size with walls of these materials were employed, and were filled with a variety of gases--N/sub 2/, CO/sub 2/, Ne, Ar, Kr, and Xe. A calibrated neutron source was employed, allowing a straightforward determination of the kerma per unit fluence.

Goldberg, E.; Slaughter, D.R.; Howell, R.H.

1978-04-05

243

Application of New MODIS-Based Aerosol Index for Air Pollution Severity Assessment and Mapping in Upper Northern Thailand  

Directory of Open Access Journals (Sweden)

Full Text Available This paper reports capability of a newly-proposed index called the aerosol prediction index (API in the determination and mapping of near-ground PM10 concentrations (at spatial resolution of 500 x 500 m during the 2009 and 2010 burning seasons in upper northern Thailand. API is a normalized index defined based on the difference in the observed reflectance data at two spectral bands of the MODIS instrument aboard NASA?s Terra satellite; Band 3 (blue and Band 7 (mid-infrared. Initial analysis suggested that API had strong correlation with the corresponding MODIS-AOD and AERONET-AOD with coefficient of determination (R2 about 0.62 in both cases, and also with the reference PM10 data with R2 of 0.66. In terms of predictive performance, it exhibited low bias at low PM10 condition and achieved impressive prediction accuracy with relative error of 10.78 %. The near-ground PM10 concentration map yielded from the proposed index was proved very useful in the comprehensive assessment of aerosol pollution situation over entire area at fine spatial detail. This task could not be fulfilled from sole use of the ground-based measured data or standard MODIS-AOD product. These findings indicate that API should be a promising tool for the regular monitoring of air pollution severity over the concerned area.

Chat Phayungwiwatthanakoon

2014-06-01

244

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

245

Radio Emission from Cosmic Ray Air Showers based on Shower Simulations: On the Importance of a Realistic Atmospheric Index of Refraction  

CERN Document Server

We present a macroscopic calculation of coherent electro-magnetic radiation from air showers initiated by ultra-high energy cosmic rays, based on currents obtained from three-dimensional Monte Carlo simulations of air showers in a realistic geo-magnetic field. We discuss the importance of a correct treatment of the index of refraction in air, given by the law of Gladstone and Dale, which affects the pulses enormously for certain configurations, compared to a simplified treatment using a constant index. We also provide some information about the numerical procedures referred to as EVA 1.0.

Werner, Klaus; Scholten, Olaf

2012-01-01

246

Evaluation of the Chinese New Air Quality Index (GB3095-2012) : Based on Comparison with the US AQI System and the WHO AQGs  

OpenAIRE

The “PM2.5 issue” was the tipping point for China’s clean air movement last year and the incentive for implementation of the new Air Quality Index (GB3095-2012). It is necessary to carry out an evaluation of the Chinese new AQI system based on comparison with developed countries and improve the system afterwards. The study evaluates the Chinese new Air Quality Index through comparison with the EPA AQI system and with the WHO AQGs as reference. The six mutual indicators have been sele...

Gao, Fanyu

2013-01-01

247

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 conductates (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

248

Monte Carlo evaluation of kerma in an HDR brachytherapy bunker  

International Nuclear Information System (INIS)

In recent years, the use of high dose rate (HDR) after-loader machines has greatly increased due to the shift from traditional Cs-137/Ir-192 low dose rate (LDR) to HDR brachytherapy. The method used to calculate the required concrete and, where appropriate, lead shielding in the door is based on analytical methods provided by documents published by the ICRP, the IAEA and the NCRP. The purpose of this study is to perform a more realistic kerma evaluation at the entrance maze door of an HDR bunker using the Monte Carlo code GEANT4. The Monte Carlo results were validated experimentally. The spectrum at the maze entrance door, obtained with Monte Carlo, has an average energy of about 110 keV, maintaining a similar value along the length of the maze. The comparison of results from the aforementioned values with the Monte Carlo ones shows that results obtained using the albedo coefficient from the ICRP document more closely match those given by the Monte Carlo method, although the maximum value given by MC calculations is 30% greater. (note)

249

Monte Carlo evaluation of kerma in an HDR brachytherapy bunker.  

Science.gov (United States)

In recent years, the use of high dose rate (HDR) after-loader machines has greatly increased due to the shift from traditional Cs-137/Ir-192 low dose rate (LDR) to HDR brachytherapy. The method used to calculate the required concrete and, where appropriate, lead shielding in the door is based on analytical methods provided by documents published by the ICRP, the IAEA and the NCRP. The purpose of this study is to perform a more realistic kerma evaluation at the entrance maze door of an HDR bunker using the Monte Carlo code GEANT4. The Monte Carlo results were validated experimentally. The spectrum at the maze entrance door, obtained with Monte Carlo, has an average energy of about 110 keV, maintaining a similar value along the length of the maze. The comparison of results from the aforementioned values with the Monte Carlo ones shows that results obtained using the albedo coefficient from the ICRP document more closely match those given by the Monte Carlo method, although the maximum value given by MC calculations is 30% greater. PMID:15724543

Pérez-Calatayud, J; Granero, D; Ballester, F; Casal, E; Crispin, V; Puchades, V; León, A; Verdú, G

2004-12-21

250

Measurement of the nonlinear refractive index of air and other gases at 248 nm  

Science.gov (United States)

The self-phase modulation of 10 ps laser pulses at 248 nm passing through a focus in a gas cell has been used to determine the nonlinear refractive indices of air, nitrogen, oxygen, methane, argon and neon and to put an upper limit on the value for helium.

Shaw, M. J.; Hooker, C. J.; Wilson, D. C.

1993-11-01

251

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

Directory of Open Access Journals (Sweden)

Full Text Available 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 air quality index to help prepare decision makers, which could rank a state according to the different levels of multiple air pollutants. The index is developed for use with principal com-ponent analysis and an algebra about a line segment, and then applied to the US transportation sector using data on five air pollutants (CO, NOx, PM, SO2, and VOCs in 2008. This study finds that some states were less polluted or more polluted in terms of the index, although their GDP levels for a transport mode were similar to each other. Thus, this finding implies that the necessary actions for stricter air quality standards must be taken in their boundaries.

Jaesung Choi

2015-02-01

252

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

Science.gov (United States)

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

Thambavani, D Sarala; Kamala, C

2010-10-01

253

Neutron kerma factors for magnesium and aluminium measured with low-pressure proportional counters  

International Nuclear Information System (INIS)

Low-pressure proportional counters enable the simultaneous determination of neutron absorbed dose in the detector wall material and of ionisation yield spectra. In well defined neutron fields the kerma to fluence ratio (kerma factor) can be evaluated from the absorbed dose results. To date this type of investigation has been performed mainly with the compound tissue-equivalent material A-150 plastic. The determination of elemental kerma factors with the proportional counter method is applicable to those materials which enable the construction of electrically conductive chamber walls. In the present investigation, kerma factor measurements with aluminium- and magnesium-walled proportional counters were performed at neutron energies of 13.9, 15.0, 17.0 and 19.0 MeV. The gas-to-wall absorbed dose conversion factors were assessed making use of the measured ionisation yield spectra. Up to 17 MeV neutron energy the measured kerma factors are in good agreement with values calculated by Caswell et al and Dimbylow. At 19.0 MeV the measured results are significantly higher than those of Caswell et al but are in good agreement with those of Dimbylow. (author)

254

Energy and kerma dependence of the Czechoslovak dosimetric Si-diode  

International Nuclear Information System (INIS)

The dose-response relationships were studied the Czechoslovak long base silicon diode in a neutron field. Diodes were manufactured from an N type silicon monocrystal and were 1.2x1.8x1.8 mm3 in size; the response of such diodes is given by the change in voltage on the diode during the flow of a constant 25 mA forward current. The properties of the diode were studied in neutron fields from the following sources: 252Cf, U 120 M isochronous cyclotron, WWR-S research reactor, pulse reactors IBR-30 and IBR-2. The found variation of voltage changes with tissue kerma of neutrons were not linear and their shape depended on the energy spectrum of the neutrons, thus differing from one source to another. The variation could well be approximated by the function K/sub n/=a?U/sup b/ (K/sub n/ - tissue kerma, energy dependence of the diodes and the errors which may occur in the determination of kerma in an unknown neutron field. Within the kerma value range of 0.5 to 30 Gy the uncertainty of determining kerma is given by the factor 1.3+-1. (A.K.)

255

Precision positioning with suppression of the influence of refractive index of air.  

Czech Academy of Sciences Publication Activity Database

Bellingham : SPIE, 2013, 878831:1-7. 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 GA102/09/1276; GA ?R GPP102/11/P820; GA TA ?R TA02010711; GA TA ?R TE01020233; GA MŠk ED0017/01/01 Institutional support: RVO:68081731 Keywords : nanometrology * refractometry * interferometry * refractive index * nanoscale Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

Holá, Miroslava; Hrabina, Jan; Oulehla, Jind?ich; ?ížek, Martin; Mikel, B?etislav; ?e?ucha, Šimon; Buchta, Zden?k; ?íp, Ond?ej; Lazar, Josef

256

Critical evaluation of neutron kerma factors using theoretical and experimental ionization yield spectra  

International Nuclear Information System (INIS)

Ionization yield calculations were performed and compared to measurements for 13.9, 15.0, 17.0 and 19.0 MeV. The measured spectra were normalized to unit neutron fluence and the calculations take account of the neutron energy distributions at the detector positions. The computer code was tested by comparison with experimental data at 0.57, 2.07 and 5.25 MeV because physical data are well known at these energies. Total kerma for 19 MeV as well as kerma due to alpha-particles for 17.0 and 19.0 MeV are significantly lower for the measured data. There is clear evidence that the 12C (n,n'3?) cross section for 17 and 19 MeV used in the calculations and in kerma evaluations is too high

257

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

258

Atomic data required in accurate measurements of kerma for neutrons with low pressure proportional counters  

International Nuclear Information System (INIS)

The accuracy achievable in neutron dosimetry for radiation therapy critically depends on the knowledge of the kerma factors for the tissue components and the detector materials. Gas filled cavity chambers allow to achieve relatively accurate measurements of kerma for the chamber wall material. Ionisation chambers and proportional counters measure with high precision the charge from ionisation produced in the gas by the charged particles released in neutron interactions with the wall and with the gas. However, the overall uncertainty of the kerma measurement depends on the quality of the basic physical data required in the application of the cavity chamber principles, in particular, W-values, stopping powers and stopping power ratios for the charged particles released and their energy dependence. The paper summarizes the experience gained in evaluating atomic data to be used in cavity chamber principles for neutron kerma measurements with tissue-equivalent and non hydrogenous proportional counters. Proportional counters with walls made of A-150 TE plastic, graphite, Al, Mg, Fe, Zr and ZrO have been used to measure neutron kerma factors by several groups. Different mixtures such as methane based TE gas, propane based TE gas or CO2 were used as counting gases. It is shown that the spectral information provided by the proportional counters can be used to assess quantities such as the gas-to-wall absorbed dose conversion factor. An attempt is made to assess the factor. An attempt is made to assess the uncertainties in kerma measurements due to the uncertainties of basic atomic data. (author). 40 refs, 12 figs, 5 tabs

259

Spatial variation of dose and kerma in a composite slab - an interface study  

International Nuclear Information System (INIS)

This work investigates the spatial variation of kerma and dose, when 60Co, 4 MV and 6 MV conical photon beams are incident on composite slab in contact geometry. Discontinuities in both kerma and dose profiles have been observed at the interfaces. The influence of Bone+Marrow (BM) on dose and secondary-electron fluence, in the Fat-BM interface, have mainly been discussed in this work. It is seen that at the Fat-BM interface, the dose has been enhanced by about 3 %, at 0.25 mm in the backward direction, for all photon beams considered in the calculations. (author)

260

Spectral index of high-energy cosmic rays by the Compton-Getting effect at solar time frame with the Tibet air shower array  

Energy Technology Data Exchange (ETDEWEB)

We report on the spectral index of cosmic rays around 10 TeV energy region obtained by observation of the Compton-Getting anisotropy due to the terrestrial orbital motion around the Sun with the Tibet III air shower array during the period from 1999 to 2005. The spectral index has turned out to be 2.99{+-}0.54, which is consistent with 2.74 by the direct energy spectrum measurement. This method is a new approach to measure the spectral index and is complementary to the conventional energy spectrum measurement.

Amenomori, M. [Department of Physics, Hirosaki University, Hirosaki 036-8561 (Japan); Ayabe, S. [Department of Physics, Saitama University, Saitama 338-8570 (Japan); Bi, X.J. [Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Chen, D. [Faculty of Engineering, Yokohama National University, Yokohama 240-8501 (Japan); Cui, S.W. [Department of Physics, Hebei Normal University, Shijiazhuang 050016 (China); Danzengluobu [Department of Mathematics and Physics, Tibet University, Lhasa 850000 (China); Ding, L.K. [Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Ding, X.H. [Department of Mathematics and Physics, Tibet University, Lhasa 850000 (China); Feng, C.F. [Department of Physics, Shandong University, Jinan 250100 (China); Feng, Zhaoyang [Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Feng, Z.Y. [Institute of Modern Physics, South West Jiaotong University, Chengdu 610031 (China); Gao, X.Y.; Geng, Q.X. [Department of Physics, Yunnan University, Kunming 650091 (China); Guo, H.W. [Department of Mathematics and Physics, Tibet University, Lhasa 850000 (China); He, H.H. [Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); He, M. [Department of Physics, Shandong University, Jinan 250100 (China); Hibino, K. [Faculty of Engineering, Kanagawa University, Yokohama 221-8686 (Japan); Hotta, N. [Faculty of Education, Utsunomiya University, Utsunomiya 321-8505 (Japan); Hu, Haibing [Department of Mathematics and Physics, Tibet University, Lhasa 850000 (China); Hu, H.B. [Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China)] (and others)

2008-01-15

261

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

Science.gov (United States)

The AIRS Science Team Version-6 retrieval algorithm recently became operational and was used to reprocess all AIRS/AMSU data, starting from September 2002, and continues to the present. We have studied the characteristics of AIRS Version-6 monthly mean level-3 products, generated on a 1°x 1° lat-lon spatial grid, over the 11 year time period September 2002 through August 2013. Of particular interest are the anomaly time series of Version-6 monthly mean 1°x 1° gridded products, given by their difference from monthly climatologies which we generated by taking the 11 year mean of the monthly mean grid point values for that month. We have generated separate climatologies based only on retrievals done using ascending Aqua orbit 1:30 PM local time observations; based only on descending 1:30 AM local time observations; and also based on the average of the 1:30 AM/1:30 PM observations. AIRS Version-6 has many significant improvements over the previously operational Version-5 retrieval algorithm. One of the major improvements in retrieval methodology is that surface skin temperatures, over both land and ocean, are now determined using observations only in the shortwave spectral range 2400 cm-1 to 2664 cm-1. Using these channels, surface skin temperature is determined simultaneously with shortwave surface spectral emissivity and surface spectral bi-directional reflectance of solar radiation. Surface longwave spectral emissivity is determined in a subsequent step using AIRS observations between 738 cm-1 and 1250 cm-1. Over the time period under study, day/night average land surface skin temperature anomalies are highly positively correlated in time over some arid tropical land areas with the NOAA Niño-4 Index, especially over Australia and South Africa. The Niño-4 Index is a measure of El Niño/La Niña activity and is highly positive during a strong El Niño event and highly negative during a strong La Niña event. These positive anomaly correlations are very large during the day, but drop off significantly at night. As a consequence of these correlations, daytime land surface skin temperatures over Australia and South Africa have cooled considerably over the 11 year time period during the day, but not at night. This local cooling is attributed to the fact that there was a moderately strong El Niño in 2003, corresponding to locally warm land surface skin temperature anomalies during the day; and there were strong La Niña events toward the end of the time period, corresponding to locally large negative daytime land surface skin temperature anomalies at the end of the time period. Very little cooling took place at night in these areas. The cooling of land surface skin temperatures in these regions appears to be unrelated to the considerable warming that took place over this time period poleward of 70°N between 30°E and 160°E, in which anomalies were for the most part uncorrelated with El Niño activity.

Susskind, J.; Lee, J.; Iredell, L.

2013-12-01

262

Particulate Matter Concentrations and the Air Quality Index in the Central Part of Tehran City, Tehran, Iran  

Directory of Open Access Journals (Sweden)

Full Text Available Background and Aim: The association between particulate matter (PM and cardiovascular diseases (CVD was shown in the mid-1990 through several epidemiological studies. Increased hospital admissions of patients with cardiovascular and respiratory problems in days when, due to high concentrations of PM, air pollution is high, bears witness to this. In this study we measured concentrations of the PM fractions in the air in the central part of Tehran city, Tehran, Iran Methods and Materials: The concentrations of suspended particles (PM10, PM2.5 and PM1 were measured during February-June 2007 in two stations in central Tehran. Stations1 was in the Enghelab Square, a crowded part of the city with highly polluted air, where many educational institutes (e.g. Tehran University are located, while station 2 was located near the Nasr Bridge, through which one of the most important highways (Martyr Chamran Highway passes. The MP concentrations were measured once every 3 days, twice each day, once during the morning traffic rush hour (9-11 AM and once during the afternoon traffic rush hour (4-6 PM, using a portable device, e.g., Environmental Dust Monitor Model GRIMM107.Results: One-way ANOVA tests showed significant differences (p<0.05 between PM concentration in the two stations. The daily mean concentrations of PM10, PM2.5 and PM1were, respectively, 77.67, 44.46 and 26.89 ?mm-3, in station 1, and 55.31, 28.15 and 19.12 ?mm-3, in station 2."nConclusion: The concentrations of PM10, PM2.5 and PM1 were lower in both stations than the respective USEPA 24-hour primary NAAQS standards, established in 1987 for PM10 and in 1999 for PM2.5. However, the proportions of the total samples with PM concentrations exceeding the new EPA standards established in 2006 were 67% and 25% in stations 1 and 2, respectively. The air quality index (AQI was unhealthy in 32% and 10.5% of the samples in stations 1 and 2, respectively. In addition, PM2.5 was the indicator pollutant in 87% of the samples in station 1 and 82% of the samples in station 2.

A R Mesdaghinia

2009-03-01

263

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

264

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)

265

New calculation method of neutron kerma coefficients for carbon and oxygen below 30 MeV  

International Nuclear Information System (INIS)

On the basis of the statistical theory of a neutron-induced light nucleus reaction, a new kerma coefficient calculation formula, expressed as k?=NijkEijk(En)?ijk(En), is developed in this paper. In an analysis of the n+12C and n+16O reactions below 30 MeV, the average energies Eijk of emitted particles of all kinds in the laboratory frame are derived in detail for different channels, allowing an exact energy balance. The optical model parameters of neutron and charged particles, which had reproduced very well the outgoing neutron double-differential cross sections in our early works, are used to obtain the cross sections ?ijk. The calculated partial, elastic recoil, and total kerma coefficients for carbon and oxygen are consistent with existing experimental kerma coefficient data. The elastic cross sections and the first Legendre coefficients of elastic angular distribution derived from EBDF/B-VIIb3 are used in this paper to improve significantly the elastic recoil and total kerma coefficients

266

Assessment of skin entrance Kerma in the United States: the nationwide evaluation of X ray trends (next)  

International Nuclear Information System (INIS)

The Nationwide Evaluation of X ray Trends (NEXT) is an annual survey programme to estimate national skin entrance air kerma, free-in-air, for representative diagnostic X ray examinations. It is conducted in the United States cooperatively between the federal government's Food and Drug Administration (FDA) and the various state and local governments through the coordinating agency known as the conference of Radiation Control Program Directors (CRCPD). NEXT originally began in 1973 and in 1983 it underwent a major change; limiting the annual survey to one examination, using standard attenuation phantoms for the measurement of exposure, empirically evaluating film processing, and the collection of comprehensive technical data such as tube potential, half value layer (HVL), type of film, screen, grid, and optical density of the resulting phantom radiograph. Surveys have been performed for chest radiography (1984 and 1986), the abdomen and lumbosacral spine examination (1987 and 1989), mammography (1985 and 1988), computerised tomography (CT) (1990), and currently fluoroscopy (1991). The mammography and fluoroscopy examinations differ from the other surveys by incorporating image quality test objects

267

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

Science.gov (United States)

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.

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

2012-01-01

268

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)

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.

LaShanta J. Rice

2014-05-01

269

Measured neutron carbon kerma factors from 14.1 MeV to 18 MeV  

International Nuclear Information System (INIS)

For A-150 tissue-equivalent plastic, the total neutron kerma is dominated by the hydrogen kerma. Tissue kerma is inferred with reasonable accuracy by normalization to the kerma factor ratio between tissue and A-150 plastic. Because of the close match in the hydrogen abundance in these materials, the principal uncertainty is due to the kerma factors of carbon and oxygen. We have measured carbon kerma factor values of 0.183 +- 0.015 10-8 cGy cm2 and 0.210 +- 0.16 10-8 cGy cm2 at 14.1-MeV and 15-MeV neutron energy, respectively. A preliminary value of 0.297 +- 0.03 10-8 cGy cm2 has been determined at 17.9 MeV. A recent microscopic cross section measurement of the (n,n'3?) reaction in carbon at 14.1-MeV energy gives a kerma factor of 0.184 +- 0.019 108 cGy cm2 in agreement with the present result. 9 refs., 4 figs., 2 tabs

270

Elucidating inequality in Nubia: An examination of entheseal changes at Kerma (Sudan).  

Science.gov (United States)

Located 10 km south of the Third Cataract of the Nile River, the ancient city of Kerma was once capital to the second largest state in Africa. The Eastern Cemetery at Kerma (?4 km east of city center) encompasses 80+ hectares and was used over a period of 1,500 years (3,200-1,500 BC). Excavated in the early 20th century by George Reisner, the cemetery contained an estimated 20,000-40,000 individuals. Reisner classified these burials into multiple categories, including chiefs and human sacrifices, based on burial position and grave goods. This study investigates the skeletal embodiment of social inequality by examining variation in entheseal severity between the Kerma burial classifications. Seventeen entheses were examined using the Hawkey and Merbs (1995) scoring method (n?=?205 individuals); age, sex, and body size variables were considered by employing Mann-Whitney U tests and partial Spearman's correlations. This analysis suggests that significant differences in entheseal changes existed between select burial types. Specifically, "corridor sacrifices" had significantly higher rates of entheseal changes while "chiefs" and "subsidiary burials" had similar entheseal changes; furthermore, within these burial categories, males had higher entheseal scores despite body size controls. The elevated entheseal changes in the sacrificial burials may be due to an intensive agro-pastoral lifestyle or other demanding forms of manual labor. In conclusion, the disparity of entheseal markers between burial subgroups at Kerma might reflect a degree of social inequality within this state level society. This bioarchaeological research informs our understanding of socially-defined categories of persons as well as everyday life in Ancient Kerma. Am J Phys Anthropol 156:192-202, 2015. © 2014 Wiley Periodicals, Inc. PMID:25327628

Schrader, Sarah A

2015-02-01

271

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

272

A radiation exposure index for CT  

International Nuclear Information System (INIS)

The purpose of this study is to define an Exposure Index for CT (EICT) and to estimate the magnitude of the EICT for common clinical CT examinations. For a single-axial rotation of a CT X-ray tube that includes only rays that pass through the patient, the CT Exposure Index (EICT) is defined as the average Air Kerma that would be incident on an extended 360 deg. detector array completely surrounding the patient. For an axial scan of a uniform cylindrical phantom, EICT can be approximated as T x [(CTDIair)/4] x [?deg./360 deg.] where T is the fractional transmission through the cylinder, CTDIair is the CT Dosimetry Index-determined 'free in air' at isocentre, and ?/2 is the fan beam angle that will completely irradiate a cylindrical phantom at isocentre. The value of CTDIair can be estimated from the weighted CTDI (CTDIw) for a given CT examination, and the angle ? depends on the irradiation geometry that can be obtained from the cylinder diameter (r) and the focus to isocentre distance (R). At a voltage of 120 kV, transmission through an adult head was ?2.6%, through an adult abdomen?0.4% and through a 5-y-old paediatric abdomen ?3%. Average ratios of CTDIair/CTDIw were 1.42±0.12 in 16-cm dosimetry phantom and 2.82±0.37 in 32-cm phantom. Values of b ranged from 30.18 (R = 61 cm and r =8 cm) to 85.38 (R = 55 cm and r=20 cm). For an adult head CT examicm). For an adult head CT examination, EICT was estimated to be?70 ?Gy at a CTDIvol of 75 mGy (16 cm), and for an adult abdominal CT examination, EICT was estimated to be?11 ?Gy at a CTDIvol of 25 mGy (32 cm). For an abdomen CT examination in a 5-y-old child, EICT was estimated to be ?21 ?Gy at a CTDIvol of 20 mGy (16 cm). The EICT is introduced that provides a quantitative measure of the amount of the radiation used to generate images in any CT examination and is analogous to the average image receptor Exposure Index recently proposed for use in projection imaging. The EICT metric provides operators with an objective index of the amount of the radiation used to create CT images and can be used to control quantum mottle in CT. (authors)

273

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

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

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

274

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.

275

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

DEFF Research Database (Denmark)

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.

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

2008-01-01

276

NOTE: Studies on effective atomic number, electron density and kerma for some fatty acids and carbohydrates  

Science.gov (United States)

The effective atomic number, Zeff, the effective electron density, Nel, 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 Zeff and Nel is due to the variations in the dominance of different interaction processes in different energy regions. The maximum values of Zeff and Nel are found in the low-energy range, where photoelectric absorption is the main interaction process. The minimum values of Zeff and Nel are found at intermediate energies, typically 0.05 MeV < E < 5 MeV, where Compton scattering is dominant. In this case, Zeff is equal to the mean atomic number of the bio-molecule. Wherever possible, the calculations are compared with experimental results. A comparison is also made with the single values of the Zeff and Nel 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 MeV range, where Compton scattering is the main interaction process.

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

2008-10-01

277

Study of the properties of aerosols and the air quality index using a backscatter lidar system and AERONET Sunphotometer in the City of São Paulo, Brazil.  

Science.gov (United States)

Between the months of July and September of 2007 during the so-called Brazilian dry season, an aerosol profiling campaign was carried out with a backscatter(ing) lidar system in the city of São Paulo, Brazil. The main goal of this campaign was to observe the aerosol load in the troposphere (up to 10 km) and its daily behavior to check for air dispersion conditions, planetary boundary, and mixed layer height daily evolution. Lidar analysis provided aerosol optical properties in the visible range (532 nm) and quantities such as aerosol backscatter(ing) and extinction coefficients in conjunction with the aerosol optical thickness provided by a collocated AERONET Sunphotometer. Altogether 61 days were used in the dataset, which were compared with air quality indexation from the local air quality monitoring and management agency. PMID:20437773

Landulfo, Eduardo; Lopes, Fábio J S; Mariano, Glauber L; Torres, Ani S; de Jesus, Wellington C; Nakaema, Walter M; Jorge, Maria P P M; Mariani, Rauda

2010-04-01

278

A consistent set of neutron kerma coefficients from thermal to 150 MeV for biologically important materials  

Energy Technology Data Exchange (ETDEWEB)

Neutron cross sections for nonelastic and elastic reactions on a range of elements have been evaluated for incident energies up to 150 MeV. These cross sections agree well with experimental cross section data for charged-particle production as well as neutron and photon production. Therefore they can be used to determine kerma coefficients for calculations of energy deposition by neutrons in matter. Methods used to evaluate the neutron cross sections above 20 MeV, using nuclear model calculations and experimental data, are described. Below 20 MeV, the evaluated cross sections from the ENDF/B-VI library are adopted. Comparisons are shown between the evaluated charged-particle production cross sections and measured data. Kerma coefficients are derived from the neutron cross sections, for major isotopes of H, C, N, O, Al, Si, P, Ca, Fe, Cu, W, Pb, and for ICRU-muscle, A-150 tissue-equivalent plastic, and other compounds important for treatment planning and dosimetry. Numerous comparisons are made between our kerma coefficients and experimental kerma coefficient data, to validate our results, and agreement is found to be good. An important quantity in neutron dosimetry is the kerma coefficient ratio of ICRU-muscle to A-150 plastic. When this ratio is calculated from our kerma coefficient data, and averaged over the neutron energy spectra for higher-energy clinical therapy beams [three p(68)+Be beams, and a d(48.5)+Be beam], a value of 0.94{plus_minus}0.03 is obtained. Kerma ratios for water to A-150 plastic, and carbon to oxygen, are also compared with measurements where available. {copyright} {ital 1999 American Association of Physicists in Medicine.}

Chadwick, M.B. [University of California, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Barschall, H.H. [Department of Medical Physics, University of Wisconsin, Madison, Wisconsin 53706-1532 (United States); Caswell, R.S. [National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); DeLuca, P.M. [Department of Medical Physics, University of Wisconsin, Madison, Wisconsin 53706-1532 (United States); Hale, G.M. [University of California, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Jones, D.T. [National Accelerator Centre, Faure, CapeTown (South Africa); MacFarlane, R.E. [University of California, Los Alamos, National Laboratory, Los Alamos, New Mexico 87545 (United States); Meulders, J.P. [Universite Catholique de Louvain, Louvain-la-Neuve (Belgium); Schuhmacher, H.; Schrewe, U.J. [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany); Wambersie, A. [Universite Catholique de Louvain, Louvain-la-Neuve (Belgium); Young, P.G. [University of California, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

1999-06-01

279

Primary standardization of 137Cs Amersham source in terms of air kerma strength  

International Nuclear Information System (INIS)

The objective of the present work was to determine the AKS of the source using the primary graphite chamber and compare with the value quoted in the certificate so as to have an indirect intercomparison with NIST, USA

280

Primary standardization of the HDR 192Ir source in terms of air kerma strength  

International Nuclear Information System (INIS)

Establishing a primary standard of AKS at the Standards Laboratory and offering traceable calibration to all the hospitals that make use of HDR 192Ir, in brachytherapy is important. With this objective, the primary standardization of the HDR 192Ir source was undertaken. Details of the work are presented

281

BIPM and COMECON comparisons of air kerma standards in X- and ?-radiation fields  

International Nuclear Information System (INIS)

The results of comparisons undertaken by a regional metrology organization at several x- and ?-ray qualities are compared with those of BIPM international comparisons. The results are statistically coherent in most cases. (authors)

282

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 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

283

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.)

284

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

285

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...

286

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)

Full Text Available SciELO Brazil | Languages: English, Portuguese Abstract in english 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.

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

2013-12-01

287

Application of the quality index methodology for dosimetric verification of build-up effect beyond air-tissue interface in treatment planning system algorithms  

International Nuclear Information System (INIS)

We have designed a simple benchmark test for the user of a treatment planning system to check the calculation algorithm's ability to model the build up effect beyond an air/tissue interface. The expected result is expressed as an inhomogeneity correction factor CF derived from measurements and from Monte Carlo calculations for a full range of photon beam qualities. The linear regression lines obtained from plotting CF as a function of beam quality index form the basis for a quantitative check of the algorithm performance

288

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

Energy Technology Data Exchange (ETDEWEB)

The effective atomic number, Z{sub eff}, the effective electron density, N{sub 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{sub eff} and N{sub el} is due to the variations in the dominance of different interaction processes in different energy regions. The maximum values of Z{sub eff} and N{sub el} are found in the low-energy range, where photoelectric absorption is the main interaction process. The minimum values of Z{sub eff} and N{sub el} are found at intermediate energies, typically 0.05 MeV < E < 5 MeV, where Compton scattering is dominant. In this case, Z{sub eff} is equal to the mean atomic number of the bio-molecule. Wherever possible, the calculations are compared with experimental results. A comparison is also made with the single values of the Z{sub eff} and N{sub 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 MeV range, where Compton scattering is the main interaction process. (note)

Manohara, S R; Hanagodimath, S M [Department of Physics, Gulbarga University, Gulbarga-585 106, Karnataka (India); Gerward, L [Department of Physics, Technical University of Denmark, DK-2800 Lyngby (Denmark)], E-mail: smhmath@rediffmail.com

2008-10-21

289

KAOS-V code: An evaluation tool for neutron kerma factors and other nuclear responses  

Energy Technology Data Exchange (ETDEWEB)

The accurate evaluation of neutron fluence-to-kerma factors from microscopic nuclear data is the subject of this report. The algorithms developed for this purpose combine in a consistent manner the two basic methods for computing kerma factors, namely kinematics and direct energy balance. These algorithms are implemented in the code KAOS-V which was used as the main evaluation tool to construct the response function library KAOS/LIB-V. KAOS-V uses data from the evaluated nuclear data files ENDF/B/V. Auxiliary nuclear data bases, e.g., the Japanese evaluated nuclear data library JENDL-2 can be used as a source of isotopic cross sections when these data are not provided in ENDF/B-V files for a natural element. These are needed mainly to estimate average quantities such as effective Q-values for the natural element. The code has the ability to compare the different results which aids in the choice of a consistent set of algorithms to evaluate kerma factors. Data in ENDF/B-IV and ENDF/B-V format can be processed. For resonance treatment, the code has the ability to access NJOY and NPTXS interface files in formatted or binary forms. No input instructions are necessary to run the code interactively. The user can simply respond to the interactive messages sent by the code if an INPUT file is absent. An INPUT file is automatically generated following an interactive run, and can be edited and used to rerun or produce different results. Grouped and point output data can be produced along with graphic representation. These features are instrumental in detecting and understanding energy balance deficiencies and other problems in the nuclear data files. 60 refs., 4 figs.

Farawila, Y.; Gohar, Y.; Maynard, C. (Georgia Inst. of Tech., Atlanta, GA (USA); Argonne National Lab., IL (USA); Wisconsin Univ., Madison, WI (USA). Dept. of Nuclear Engineering and Engineering Physics)

1989-09-01

290

Precision refractive index measurements of air, N2, O2, Ar, and CO2 with a frequency comb  

International Nuclear Information System (INIS)

We report precision measurements of the refractive indices of dry air, N2, O2, Ar, and CO2, performed by using a frequency comb as the light source in a Mach-Zehnder interferometer setup. Improved dispersion formulas for all gases are derived with a sensitivity level of 10-9. These results are valid for a wavelength range from 740 to 860 nm and are in good agreement with measurements from other groups

291

Group-phase Velocity Difference and THz Oscillation of the Nonlinear Refractive Index in Air: Particle-like Solutions  

International Nuclear Information System (INIS)

We present an analytical approach to the theory of optical pulses with superbroad spectrum propagated in air. The corresponding modified amplitude envelope equation admits oscillated with terahertz frequency nonlinear term The fluctuation is due to the group and phase velocity difference. In the partial case of femtosecond pulses with power, little above the critical for self-focusing, exact (3+1)D particle-like solution is found.

292

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

293

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)

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.

Piedad M. Cristiano

2014-02-01

294

Geomagnetic activity related NOx enhancements and polar surface air temperature variability in a chemistry climate model: modulation of the NAM index  

Directory of Open Access Journals (Sweden)

Full Text Available The atmospheric chemistry general circulation model ECHAM5/MESSy is used to simulate polar surface air temperature effects of geomagnetic activity variations. A transient model simulation was performed for the years 1960–2004 and is shown to develop polar surface air temperature patterns that depend on geomagnetic activity strength, similar to previous studies. In order to eliminate influencing factors such as sea surface temperatures (SST or UV variations, two nine-year long simulations were carried out, with strong and weak geomagnetic activity, respectively, while all other boundary conditions were held to year 2000 levels. Statistically significant temperature effects that were observed in previous reanalysis and model results are also obtained from this set of simulations, suggesting that such patterns are indeed related to geomagnetic activity. In the model, strong geomagnetic activity and the associated NOx enhancements lead to polar stratospheric ozone loss. Compared with the simulation with weak geomagnetic activity, the ozone loss causes a decrease in ozone radiative cooling and thus a temperature increase in the polar winter mesosphere. Similar to previous studies, a cooling is found below the stratopause, which other authors have attributed to a decrease in the mean meridional circulation. In the polar stratosphere this leads to a more stable vortex. A strong (weak Northern Hemisphere vortex is known to be associated with a positive (negative Northern Annular Mode (NAM index; our simulations exhibit a positive NAM index for strong geomagnetic activity, and a negative NAM for weak geomagnetic activity. Such NAM anomalies have been shown to propagate to the surface, and this is also seen in the model simulations. NAM anomalies are known to lead to specific surface temperature anomalies: a positive NAM is associated with warmer than average northern Eurasia and colder than average eastern North Atlantic. This is also the case in our simulation. Our simulations suggest a link between geomagnetic activity, ozone loss, stratospheric cooling, the NAM, and surface temperature variability.

P. Jöckel

2010-12-01

295

Use of threshold activation detectors to obtain neutron kerma for biological irradiations  

International Nuclear Information System (INIS)

Fission and non-fission activation foils have been irradiated in the experimental room at the Armed Forces Radiobiology Research Institute (AFRRI) in Bethesda, Maryland, in order to characterize the neutron field there. The field, which is generated by neutrons from a TRIGA MARK-F reactor adjacent to the room, is used for radiobiological experiments. The neutron exposure parameter, neutron tissue kerma rate per unit reactor power, is derived from individual detector measurements and an a priori spectrum obtained from neutron transport calculations. Beginning with conventional averaging of single-detector results, the analysis proceeds to a least-squares adjustment which avoids spectrum interpolation. An example is included of benchmark referencing to a fission neutron spectrum and consequent improvement in measurement confidence

296

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

297

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

298

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

Science.gov (United States)

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.

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

2013-01-01

299

Retrieval of structure functions of air temperature and refractive index from large eddy simulations of the atmospheric boundary layer  

Science.gov (United States)

A methodology is presented to infer the refractive-index structure function parameter and the structure parameters for temperature and humidity from numerical simulations of the turbulent atmospheric convective boundary layer (CBL). The method employs spatial and temporal averaging of multiple realizations of the CBL flow field reproduced by a large-eddy simulation (LES) of the atmosphere. The Cn2 values yielded by LES-based approach agree fairly well with Cn2 values predicted by the Monin-Obukhov similarity theory. In this respect, the Cn2 retrieval from the LES data is promising for evaluating the vertical profile of Cn2 throughout the entire CBL. Under the considered CBL conditions and for the selected optical wavelength of 0.55 ?m the value of Cn2 was found to be dominated by the CT2 contribution in the first few hundred meters above the surface, whereas the CTq contribution became significant aloft.

Wilson, Chris; van Eijk, Alexander M.; Fedorovich, Evgeni

2013-09-01

300

Air Pollution Quality Index (AQI and Density of PM1, PM2.5 and PM10 in the Air of Qom  

Directory of Open Access Journals (Sweden)

Full Text Available Background and Objectives: Air pollution has broad social, economical, political and technical aspects. one of the major issues in this regard is taking measures to prevent its increase. Since suspended particles are among the standard pollutants, the present study was carried out with the aim of measuring the amounts of these particles.Methods: In the present study, the suspended particles ( PM1, PM2.5 and PM10 were measured at two sites in Qom city. For each of them, 60 samples were selected with the Enviro Check during five consecutive months during summer (2 months and fall.Results: During sampling, PM10 in the period between October 22'th to November 22nd 2007 had the maximum amount with the mean of 117µg/m3 and in the period between September 22'th to October 22nd 2007 it had the minimum amount with the mean of 83µg/m3. PM2.5 in the period between November 22nd to December 22nd 2007 with the mean of 33µg/m3 had the maximum amount and in the period between July 22nd to October 22nd 2007 it had the minimum amount with the mean of 8µg/m3. Conclusion: Based on the findings of this study, the densities of suspended particles PM1, PM2.5 and PM10 were below the standard levels on most occasions. The amounts of AQI for them were normal and acceptable.

Safdari M

2011-06-01

301

ZZ RFL-2-DTF, Group Constant Library of Reaction Cross-Section, Gas Production, Kerma, DPA  

International Nuclear Information System (INIS)

1 - Description of program or function: Format: DTF format and the structure is adopted from the MACKLIB-IV library. Number of groups: group library of reaction cross sections, gas production, kerma and DPA. Materials: H-1, H-2, H-3, He-3, He-4, Li-6, Li-7, Be-9, B-10, B-11, C-Nat, N-14, N-15, O-16, F-19, Na-23, Mg-Nat, Al-27, Si-28, P-31, S-Nat, Cl-Nat, Ar-36, Ar-38, Ar-40, K-Nat, Ca-Nat, Ti-Nat, V-Nat, Cr-50, Cr-52, Cr-53, Cr-54, Mn-55, Fe-54, Fe-56, Fe-57, Fe-58, Co-59, Ni-58, Ni-60, Ni-61, Ni-62, Ni-64, Cu-63, Cu-65, Zr-Nat, Nb-93, Mo-92, Mo-94, Mo-95, Mo-96, Mo-97, Mo-98, Mo-100, Ag-107, Ag-109, Cd-Nat, In-113, In-115, Sn-112, Sn-114, Sn-115, Sn-116, Sn-117, Sn-118, Sn-119, Sn-120, Sn-12,2 Sn-124, Ba-130, Ba-134, Ba-135, Ba-136, Ba-137, Ba-138, Hf-174, Hf-176, Hf-177, Hf- 178, Hf-179, Hf-180, Ta-181, W-Nat, W-182, W-183, W-184, W-186, Re-185, Re-187, Pb-Nat, Bi-209. Temperatures: T=293.6 K. Origin: GEFF-2 and GEPDL. RFL-2 is a group library of reaction cross sections, gas production, kerma and DPA based upon GEFF-2 and GEPDL - which are included in the package ZZ-GEFF-2-GENDF - and upon DECNET - included in the ZZ-DECNET-GENDF package (see below the description of these libraries). RFL-2 has been derived from them by the GENTORFL code (GENdf To RFL). Its primary use is to complete the neutron transport libraries in ANISN or FIDO format with data normally not present in the traditional files. It includes all GEFF-2 materials at T=293.6 K and ?0 = infinity; as quals at T=293.6 K and ?0 = infinity; as qualifying point it gives 'delayed' kerma and 'delayed' gamma-ray production matrices, i.e. the energy release and the photons, respectively, generated by the decay of radioactive nuclei produced in the primary reactions; decay events that occur within 10000 seconds from the primary reaction are taken into account. The library includes many isotopes, since for each natural element included in GEFF-2 the decay of all component isotopes have been traced out. The library is in DTF format and the structure is adopted from the MACKLIB-IV library. The list of the included materials is given in one separate file. The position of the reactions in the RFL-2 matrix are given in the ZZRFL2.POS file. Source libraries GEFF-2: This P5 library for fusion neutronics calculations is based upon the 175 neutron, 42 photon VITAMIN-J group structure with the standard weighting function: Maxwellian (at the temperature to which the material is referenced) + 1/E + fission spectrum + 1/E + fusion peak + 1/E. It includes 93 materials - almost all from EFF-2 basic data; but Ag-107, Ag-109, natural Cd, the 6 Hf isotopes and the 4 W isotopes have been taken from JEF-2.2 - at 3 temperatures and 6 dilution values; 10 thermal groups are provided below 3 eV. Neutron cross sections and diffusion matrices, photon and gas production, kerma and DPA are given. GEPDL: GEPDL is a 42 group photon interaction P8 library based upon EPDL-90 to be used in conjunction with GEFF-2 for preparing neutron + photon coupled libraries by means of codes such as MATXSR - to produce data for TRANSX - or SMILER - an AMPX-77 module to produce AMPX Master Libraries from GENDF structured data. DECNET: DECNET is a library for fusion damage computations of 175 neutron +42 photon VITAMIN-J energy group with the standard weighting function: Maxwellian (at the temperature to which the material is referenced) + 1/E + fission spectrum + 1/E + fusion peak + 1/E; it includes neutron kerma and gamma-ray production data from radioactive nuclei at 3 temperatures with the same materials of ZZ-GEFF-2-GENDF (see below) from 1-H-1 to Bi-209, mostly taken from EFF-2 with some nuclides from JEF-2.2 - Ag-107, Ag-109, Cd, the 6 Hf isotopes and the 4 W isotopes; however the list of the materials disagrees with that of GEFF-2 in that all elemental nuclides have been split into the components isotopes to follow the respective decay chain; and not all materials of GEFF-2 produce nuclei which disintegrate within the assumed decay time of 10000 seconds delay from the primary events which produced the rad

302

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)

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)

Santos, Alexandre Lo Bianco dos

2011-07-01

303

NOTE: Monte Carlo evaluation of kerma in an HDR brachytherapy bunker  

Science.gov (United States)

In recent years, the use of high dose rate (HDR) after-loader machines has greatly increased due to the shift from traditional Cs-137/Ir-192 low dose rate (LDR) to HDR brachytherapy. The method used to calculate the required concrete and, where appropriate, lead shielding in the door is based on analytical methods provided by documents published by the ICRP, the IAEA and the NCRP. The purpose of this study is to perform a more realistic kerma evaluation at the entrance maze door of an HDR bunker using the Monte Carlo code GEANT4. The Monte Carlo results were validated experimentally. The spectrum at the maze entrance door, obtained with Monte Carlo, has an average energy of about 110 keV, maintaining a similar value along the length of the maze. The comparison of results from the aforementioned values with the Monte Carlo ones shows that results obtained using the albedo coefficient from the ICRP document more closely match those given by the Monte Carlo method, although the maximum value given by MC calculations is 30% greater.

Pérez-Calatayud, J.; Granero, D.; Ballester, F.; Casal, E.; Crispin, V.; Puchades, V.; León, A.; Verdú, G.

2004-12-01

304

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

OpenAIRE

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 ...

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

2002-01-01

305

Validity of constant room scatter assumption in the air kerma strength standardization of a remote afterloading 192Ir HDR source  

International Nuclear Information System (INIS)

The objective of the present study is to examine the validity of the constant room scatter assumption for rooms of various sizes (including the room size where the standardization of a 192Ir HDR source was carried out) for a remote afterloading micro selectron 192Ir HDR source. The well-established Monte Carlo simulation code MCNP (Version 3.1, 1980) was used in the study

306

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)

307

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.

308

Assessment of effects of air pollution on the ring width of Japanese cedars (Cryptomeria Japonica D. Don) (2). Relationships between the standardized ring index and the pollution levels of SO sub 2 and NO sub 2 in the ambient air at the surrounding area of thermoelectric power stations  

Energy Technology Data Exchange (ETDEWEB)

Effects of air pollution on the growth of cedar by ring width analysis of core samples of cedar in the arena of thermal power station in Fukui Prefecture with correction of tree-age and climate conditions. As the index of air pollution, SO{sub 2}, NO{sub 2}, and annual average pH value of rain water, were applied. Photo-film of soft X-ray of core sample with 5mm diameter was applied to densitometer for measuring the ring width. The result was statistically calculated to obtain standardized ring index. As the consideration of experimental result, it was understood that growth of cedar was inhibited within the range estimated by diffusion, and that effects of SO{sub 2}, NO{sub 2} were recognized but not that of acid rain. 27 refs., 6 figs., 2 tabs.

Kato, Terutaka; Kasuya, Minoru; Kagamimori, Sadanobu; Kawano, Shoichi; Kozuka, Hiroshi (Toyama Medical and Pharmaceutical Univ. (Japan); Kyoto Univ. (Japan))

1988-12-20

309

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)

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

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

310

Calculation of the backscattering in water and compared to the values in air; Calculo del factor de retrodispersion en agua y comparativa con los valores en aire  

Energy Technology Data Exchange (ETDEWEB)

The purpose of this paper is to calculate values of BSF in water and comparison with data on air 11SF found in the literature. For this simulations have been performed by the Monte Carlo method for calculating values ??kerma water in the presence of a manikin of this material and in the absence thereof. The simulations were performed for monoenergetic beams in order to facilitate the calculation of the BSF for any spectral distribution of those found in the field of radiology.

Minano Herrero, J. A.; Sarasa Rubio, A.; Roldan Arjona, J. M.

2011-07-01

311

Study of effective atomic numbers and electron densities, kerma of alcohols, phantom and human organs, and tissues substitutes  

Directory of Open Access Journals (Sweden)

Full Text Available Effective atomic numbers (ZPIeff and electron densities of eighteen alcohols such as wood alcohol, CH3OH; grain alcohol, C2H5OH; rubbing alcohol, C3H7OH; butanol, C4H9OH; amyl alcohol, C5H11OH; cetyl alcohol, C16H33OH; ethylene glycol, C2H4(OH2; glycerin, C3H5(OH3; PVA, C2H4O; erythritol, C4H6(OH4; xylitol, C5H7(OH5; sorbitol, C6H8(OH6; volemitol, C7H9(OH7; allyl alcohol, C3H5OH; geraniol, C10H17OH; propargyl alcohol, C3H3OH; inositol, C6H6(OH6, and menthol, C10H19OH have been calculated in the photon energy region of 1 keV-100 GeV. The estimated values have been compared with experimental values wherever possible. The comparison of ZPIeff of the alcohols with water phantom and PMMA phantom indicate that the ethylene glycol, glycerin, and PVA are substitute for PMMA phantom and PVA is substitute of water phantom. ZPIeff of alcohols have also been compared with human organs and tissues. Ethylene glycol, glycerin and PVA, allyl alcohol, and wood alcohols are found tissue substitutes for most of human organs. Kerma which is the product of the energy fluence and mass energy-absorption coefficient, have been calculated in the energy region from 1 keV to 20 MeV for the alcohols. The results show the kerma is more or less independent of energy above 100 keV.

Singh Vishwanath P.

2013-01-01

312

Characterization of the new free-air primary standard for low-energy X-rays at CMI  

Science.gov (United States)

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.

Šolc, Jaroslav; Sochor, Vladimír

2014-11-01

313

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

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...

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

2014-01-01

314

Power and polarization beam-splitters, mirrors, and integrated interferometers based on air-hole photonic crystals and lateral large index-contrast waveguides.  

Science.gov (United States)

Air hole 2D photonic crystals (PhC) and air slots have been used in association with semiconductor ridge waveguides to produce highly compact beam-splitters (less than 10 microm x10 microm) for power or polarization separators and mirrors. An efficiency of 99 % (in both 2D and 3D formulations) has been obtained for the power beam-splitter using finite-difference time-domain (FDTD) simulations - and around 95 % has been measured experimentally for structures realized in silicon-on-insulator (SOI) waveguides. In the polarization splitter, an extinction ratio as large as 11 dB was also reached experimentally. Examples of combinations of these elements in the form of interferometers are also presented. PMID:19516730

Pottier, Pierre; Mastroiacovo, Sara; De La Rue, Richard M

2006-06-12

315

Evaluated cross section libraries and kerma factors for neutrons up to 100 MeV on {sup 16}O and {sup 14}N  

Energy Technology Data Exchange (ETDEWEB)

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.

Chadwick, M.B.; Young, P.G.

1995-07-01

316

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

317

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)

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.

Chadwick, M.B. [California Univ., Livermor, CA (United States). Lawrence Livermore National Lab.; Young, P.G.

1997-03-01

318

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)

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)

Lima, Mateus Hilario de

2014-08-01

319

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

Energy Technology Data Exchange (ETDEWEB)

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)

Silva, J.L.D.F.; Cardoso, R.S.; Peixoto, J.G.P. [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)]. E-mail: joseluiz@ird.gov.br; ricardo@ird.gov.br; guilherm@ird.gov.br

2007-07-01

320

Evolution of the snow area index of the subarctic snowpack in central Alaska over a whole season. consequences for the air to snow transfer of pollutants.  

Science.gov (United States)

The detailed physical characteristics of the subarctic snowpack must be known to quantify the exchange of adsorbed pollutants between the atmosphere and the snow cover. For the first time, the combined evolutions of specific surface area (SSA), snow stratigraphy, temperature, and density were monitored throughout winter in central Alaska. We define the snow area index (SAI) as the vertically integrated surface area of snow crystals, and this variable is used to quantify pollutants' adsorption. Intense metamorphism generated by strong temperature gradients formed a thick depth hoar layer with low SSA (90 cm(2) g-1) and density (200 kg m(-3)), resulting in a low SAI. After snowpack buildup in autumn, the winter SAI remained around 1000 m(2)/m(2) of ground, much lower than the SAI of the Arctic snowpack, 2500 m(2) m-(2). With the example of PCBs 28 and 180, we calculate that the subarctic snowpack is a smaller reservoir of adsorbed pollutants than the Arctic snowpack and less efficiently transfers adsorbed pollutants from the atmosphere to ecosystems. The difference is greater for the more volatile PCB 28. With climate change, snowpack structure will be modified, and the snowpack's ability to transfer adsorbed pollutants from the atmosphere to ecosystems may be reduced, especially for the more volatile pollutants. PMID:17256489

Taillandier, A S; Domine, F; Simpson, W R; Sturm, M; Douglas, T A; Severin, K

2006-12-15

321

Immigration Index  

Science.gov (United States)

Striving to become the "immigration resource directory on the net," the Immigration Index is a newly launched Website dedicated to news and information about immigration worldwide. Along with breaking headlines from a variety of news sources about immigration-related issues such as asylum, migration, trafficking and women, and much more, the site contains a fully annotated collection of links to immigration materials all around the World Wide Web. Only a month old, some of the categories in the Index's hierarchy still need some filling in. In time, however, the Immigration Index promises to become an invaluable resource for interested parties.

322

Comparison of measured and calculated radiation transport in air-over-ground geometry to 1.6 km from a fission source  

International Nuclear Information System (INIS)

Neutron and gamma-ray tissue kerma and scalar spectrum measurements have been made at the Army Pulse Radiation Division (APRD), Aberdeen Proving Ground, to 1.6 km in air-over-ground geometry from a fission source and are compared to state-of-the-art transport calculations. Measurements have been made by the APRD staff as well as German, Canadian, and French scientists. A variety of integral detectors and differential spectrometers were used. Agreement among the various groups ranges from good to excellent. Calculations have been made in support of shielding programs and in connection with the Hiroshima-Nagasaki dose reevaluation effort. The DOT transport calculations have been performed at the Lawrence Livermore and Oak Ridge National Laboratories, the Defence Research Establishment, Ottawa, and at Science Applications, Inc. Monte Carlo calculations have been performed at Los Alamos National Laboratory. The calculations are generally consistent. Average calculated-to-measured kerma ratios range from 0.83 to 1.27. Calculated-to-measured neutron flux ratios vary from about 0.6 near 1 keV and about 0.8 near 5 MeV to about 1.7 near 0.8 MeV. These spectral differences tend to cancel when determining tissue kerma, raising the possibility that some of the agreement in kerma may be fortuitous. Sources of possible discrepancies are discussed

323

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 ?2 to the compact representation of documents and to the definition of the similarity of natural language texts. (author). 17 refs., 2 figs

324

[Glycaemic index].  

Science.gov (United States)

Glycaemic index is a measure of blood glucose increase two hours after intake of food containing 50 g of carbohydrate. The reference is measurements after intake of 50 g glucose or white bread containing 50 g carbohydrate, which is set to the value of 100. The glycaemic index was developed to help persons with diabetes improve their blood glucose control in order to avoid long-term complications. Apple can have an index of approximately 40, while a baguette has 95 and pumpernickel bread 41. Some observational studies suggest that a carbohydrate diet with low glycaemic index may reduce the risk of overweight, diabetes type 2 and colon cancer. There are at present few published controlled clinical trials supporting this conclusion. The food industry and some people working with weight reduction have shown interest in using the glycaemic index. The system may easily cause confusion and leave the impression that important and nutritious carbohydrate-containing foods should be avoided. The glycaemic index could be a tool for dieticians and physicians counselling persons with metabolic syndrome, overweight, diabetes type 1 or 2. PMID:14714013

Kolset, Svein Olav

2003-11-20

325

Design and preliminary test of a free-air ionization chamber for low-energy X-ray  

International Nuclear Information System (INIS)

A free-air ionization chamber in low-energy X-ray has been designed and manufactured at the National Institute of Metrology (NIM, China) according to the definition of air-kerma. The results of a preliminary test show that the leakage current of ionization chamber is around 2 x 10-15A, and the correction factor of ion recombination for the ionization chamber is also obtained. The free-air ionization chamber is suitable for the primary standard in low-energy X-rays. (authors)

326

Evaluated cross-section libraries and kerma factors for neutrons up to 100 MeV on {sup 12}C  

Energy Technology Data Exchange (ETDEWEB)

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 {sup 12}C. 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{le}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.

Chadwick, M.B.; Blann, M.; Cox, L. [Lawrence Livermore National Lab., CA (United States); Young, P.G. [Los Alamos National Lab., NM (United States); Meigooni, A. [Kentucky Univ., Lexington, KY (United States). Dept. of Radiation Medicine

1995-04-11

327

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)

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.

Mónica, Gelmi; Rafael, Seoane.

2013-06-01

328

Rib index.  

Science.gov (United States)

This article analyzes the double rib contour sign (DRCS) and the rib index (RI). The analyzed topics are 1. the history of presentations - publication of DRCS-RI, 2. the study source origin: school screening for idiopathic scoliosis (IS), 3. what the DRCS and the RI are- Description, 4. the quantification of the DRCS - RI, 5. a reliability study for RI 6. how much the rib index is affected by the distance between the radiation source and the irradiated individual, 7. the implications on IS aetiology, 8. the applications of Rib index for a. documentation of the deformity, b. assessment of physiotherapy, c. assessment of brace treatment and d. pre- and post-operative assessment; assessment of the rib-cage deformity correction on the transverse plane, 9. the use of RI and implications for screening policies 10. the reference of the RI method in spinal textbooks and finally 11. the citations in Google Scholar. PMID:25635184

Grivas, Theodoros B

2014-01-01

329

Population Index  

Science.gov (United States)

Two excellent bibliographic resources for population studies are the "Population Index" from the Office of Population Research at Princeton University, and "Population Organizations: Finder's Guide" from the Center for Demography and Ecology at the University of Wisconsin-Madison. "Population Index" is a quarterly publication that has been available since 1935. It "covers all fields of interest to demographers, including fertility, mortality, population size and growth, migration, nuptiality and the family, research methodology, projections and predictions, historical demography, and demographic and economic interrelations. Input is derived from original publications including monographs, journal articles, other serial publications, working papers, doctoral dissertations, machine-readable data files, and relevant acquisitions lists and bibliographies." About 3,500 citations are produced annually. Full text for the Index is available at the "Population Index" Web site for 1986-present (Vol. 52-present). Indexes can be searched by author, subject matter, geographical region, or publication year. There is now an experimental free text search capability for the 1994-present issues. "Population Organizations: Finder's Guide" is a no frills "practical tool for population professionals who need a single source for the quick location of organizations that publish and distribute or post population or family planning documents." It contains hundreds of citations, providing organization addresses, phone and FAX numbers, and Internet addresses when available. The Guide is updated every six months and is maintained by Ruth Sandor, Director of the Library of the Center for Demography and Ecology. Office of Population Research, Princeton University: http://opr.princeton.edu/ "Population Organizations: Finder's Guide": gopher://cde2.ssc.wisc.edu:70/00/addazlis gopher to: cde2.ssc.wisc.edu select: Population Organizations: Finder's Guide Center for Demography and Ecology, University of Wisconsin-Madison: http://www.ssc.wisc.edu/cde/

330

Conception and realization of a parallel-plate free-air ionization chamber for the absolute dosimetry of an ultrasoft X-ray beam  

Science.gov (United States)

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.

Groetz, J.-E.; Ounoughi, N.; Mavon, C.; Belafrites, A.; Fromm, M.

2014-08-01

331

Evaluation of cross sections and calculation of kerma factors for neutrons up to 80 MeV on {sup 12}C  

Energy Technology Data Exchange (ETDEWEB)

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)

Harada, M.; Watanabe, Y. [Kyushu Univ., Fukuoka (Japan); Chiba, S.; Fukahori, T.

1997-03-01

332

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

333

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)

334

Assessment of corrective factors for the LNHB reference measurement in terms of Kr air for iodine 125  

International Nuclear Information System (INIS)

The LNHB (Laboratoire National Henri Becquerel) is currently developing a new primary reference for low dose rate curietherapy with iodine 125 in terms of reference kerma in air. This includes an innovative sensor: an ionization chamber with a toroidal air wall. The authors present Monte Carlo calculations performed for the determination of corrective factors to be applied to come down to reference conditions or to correct possible measurement errors. Calculations have been performed for the specific geometries of BEBIG sources which are used for ophthalmic and prostatic curietherapy treatments

335

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

336

Air Quality  

Science.gov (United States)

... Radiation Air Quality Planning & Standards Air Quality Air Quality Announcements Greenversations Blog: New Picture Book Teaches Kids ... air pollution areas. For more information about Air Quality Monitoring, visit Monitoring Information AMTIC - The Ambient Monitoring ...

337

Ptolemaic Indexing  

CERN Document Server

This paper discusses a new family of bounds for use in similarity search, related to those used in metric indexing, but based on Ptolemy's inequality, rather than the metric axioms. Ptolemy's inequality holds for the well-known Euclidean distance, but is also shown here to hold for quadratic form metrics in general. In addition, the square root of any metric is Ptolemaic, which means that the principles introduced in this paper have a very wide applicability. The inequality is examined empirically on both synthetic and real-world data sets and is also found to hold approximately, with a very low degree of error, for important distances such as the angular pseudometric and several Lp norms. Indexing experiments are performed on several data sets, demonstrating a highly increased filtering power when using certain forms of Ptolemaic filtering, compared to existing, triangular methods. It is also shown that combining the Ptolemaic and triangular filtering can lead to better results than using either approach on ...

Hetland, Magnus Lie

2009-01-01

338

Dependence with air density of the response of the PTW SourceCheck ionization chamber for low energy brachytherapy sources  

International Nuclear Information System (INIS)

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 125I seeds.Methods: Four different SourceCheck chambers were analyzed. With each one of them, two series of measurements of the air kerma strength for 125I selectSeedTM 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

339

Double-differential cross sections and kerma coefficients for light-charged particles produced by 96 MeV neutrons on carbon  

Energy Technology Data Exchange (ETDEWEB)

Double-differential cross sections of inclusive light-ion (p, d, t, {sup 3}He and {alpha}) production in carbon induced by 96 MeV neutrons have been measured at eight laboratory angles from 20{sup o} to 160{sup o} in steps of 20{sup o}. Experimental techniques, as well as procedures for data taking and data reduction, are presented. Deduced energy-differential and production cross sections are herewith reported. Experimental cross sections are compared with theoretical reaction model calculations and experimental data in the literature. The measured production cross sections for protons, deuterons, tritons, {sup 3}He, and {alpha} particles support the trends suggested by data at lower energies. Deduced partial kerma coefficients for carbon are also shown.

Tippawan, U., E-mail: udomrat@fnrf.science.cmu.ac.t [Plasma and Beam Physics Research Facility, Department of Physics and Material Science, Chiang Mai University (Thailand); Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala (Sweden); Pomp, S.; Blomgren, J. [Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala (Sweden); Dangtip, S. [Plasma and Beam Physics Research Facility, Department of Physics and Material Science, Chiang Mai University (Thailand); Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala (Sweden); Gustavsson, C.; Klug, J. [Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala (Sweden); Nadel-Turonski, P. [Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala (Sweden); Catholic University of America, Washington, DC (United States); Osterlund, M.; Nilsson, L. [Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala (Sweden); Olsson, N. [Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala (Sweden); Swedish Defence Research Agency (FOI), Stockholm (Sweden); Jonsson, O.; Prokofiev, A.V. [Svedberg Laboratory, Uppsala University (Sweden); Corcalciuc, V. [Horia Hulubei National Institute of Physics and Nuclear Engineering, Bucharest (Romania); Koning, A.J. [Nuclear Research and Consultancy Group NRG, Petten (Netherlands); Watanabe, Y. [Department of Advanced Energy Engineering Science, Kyushu University (Japan)

2010-12-15

340

Double-differential cross sections and kerma coefficients for light-charged particles produced by 96 MeV neutrons on carbon  

International Nuclear Information System (INIS)

Double-differential cross sections of inclusive light-ion (p, d, t, 3He and ?) production in carbon induced by 96 MeV neutrons have been measured at eight laboratory angles from 20o to 160o in steps of 20o. Experimental techniques, as well as procedures for data taking and data reduction, are presented. Deduced energy-differential and production cross sections are herewith reported. Experimental cross sections are compared with theoretical reaction model calculations and experimental data in the literature. The measured production cross sections for protons, deuterons, tritons, 3He, and ? particles support the trends suggested by data at lower energies. Deduced partial kerma coefficients for carbon are also shown.

341

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)

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.

Wilson, Robert M.

2013-01-01

342

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 desirabluidelines 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

343

Measuring the Molecular Polarizability of Air  

OpenAIRE

We present an update of the "refractive index of air" experiment commonly used in optics and undergraduate advanced labs. The refractive index of air is based on the average molecular polarizability, which we measured from the period of the phase shift in a Michelson interferometer as a function of pressure. Our value of the average molecular polarizability of air is \\gamma_mol = 2.133 \\pm 0.032 \\times 10^{-29} m^3 (95% CI) and from this we find the refractive index of air a...

Madsen, M. J.; Brown, D. R.; Krutz, S. R.; Milliman, M. J.

2009-01-01

344

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 ...

345

Determination of the diaphragm correction factor of the LNE-LNHB free-air chambers for low and medium energy X-rays  

International Nuclear Information System (INIS)

Until recently, in the establishment of the French LNE-LNHB national reference in terms of air kerma for low and medium energy X-rays, the effect of the diaphragm located at the entrance of the free-air ionization chambers was not sufficiently taken into account. This report describes the different Monte Carlo computations made in 2010-2011 with the PENELOPE Monte Carlo code to determine a correction factor (kdia) describing the influence of the different incident photon interactions taking place into the diaphragm on the deposited energy in the collecting volume. (author)

346

Transport of initial radiations in air over ground  

International Nuclear Information System (INIS)

A time-dependent system of classification is normally used to divide the ionizing radiation from a nuclear explosion into two groups: initial and residual. The initial radiation is the ionizing radiation emitted within the first minute following the detonation of the weapon, and the residual radiation is the ionizing radiation emitted later. Transport calculations for the prompt and delayed radiations were performed separately and then combined at fixed ground locations to obtain the total neutron and gamma-ray fluence, together with their energy and angular distributions. Modeling of the air-over-ground transport for the delayed radiation is a more difficult task. For example, such complex effects as the rapid early-time decay of the fission products, the rise of the fireball, and the blast-enhanced transport of the delayed radiation must be considered. The blast wave from the explosion enhances the transport of the delayed radiations by removing most of the air between the fireball and the shock front. This work uses transport modeling procedures and source term data developed in studies by Science Applications International Corporation (SAIC). In their studies, the delayed neutron and gamma-ray fluences were estimated by means of a one-dimensional ANISN calculation that takes into account the air density profile at a fixed location on the ground at discrete time intervals after the explosion. The effects of ground scattering were then computed separately by means og were then computed separately by means of the VCS code. These transport modeling procedures were verified by applying them to weapon tests where time dependent gamma-ray measurements were made as a function of ground range. Many of the calculations and comparisons of this work involve the use of dosimetric parameter called kerma. Kerma equals the total kinetic energy of all the charged particles liberated by neutrons and gamma rays in a small volume of a given material divided by the mass of the material in that volume element

347

User-Centered Indexing.  

Science.gov (United States)

Distinguishes between document-oriented and user-oriented indexing and discusses the advantages and disadvantages of request-oriented and automated indexing. Request-oriented indexing is difficult to implement with human, a priori indexing. Automated indexing can be tailored to individual requests, but most research in this area focuses on global…

Fidel, Raya

1994-01-01

348

Index Funds Online  

Science.gov (United States)

Matthew Roberts recently released Index Funds Online in response to the lack of index investment fund information on the Internet. Site features include the market performance newsletter Indexing Quarterly, background and definitional information on major US Indexes such as the S&P 500, and a library of new and interesting financial Websites, articles, and book reviews. Links to current index performance figures are also provided as well as a simple site search system and index fund discussion board.

349

Refractive index of plant cell walls  

Science.gov (United States)

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.

Gausman, H. W.; Allen, W. A.; Escobar, D. E.

1974-01-01

350

Calculation of photon scattering and transmission correction factors for a free air ionization chamber at Nuclear Science and Technology Research Institute in Iran  

International Nuclear Information System (INIS)

Highlights: ? Transmission and scattering correction factors are calculated by using MCNP 4C. ? Transmission correction factor (ktr) is determined to be 1 for 6 cm aperture radius. ? Determined ktr is 0.9999 for photon energies above 85 keV for 4 cm aperture radius. ? Obtained scattering correction factor for 125I is 0.9987, for 4 cm aperture radius. ? Calculated scattering correction factor for 103Pd is 0.9992, for the same aperture. - Abstract: In primary standard dosimetry laboratories, the air kerma strength of low energy brachytherapy sources 125I and 103Pd is measured by standard free air ionization chambers. At present, one of these free air ionization chambers is constructed in Radiation Application Research School, in Nuclear Science and Technology Research Institute in Iran. The transmission and scattering correction factors are needed for the absolute determination of air kerma strength. Transmission and scattering correction factors were calculated for a monoenergetic point isotropic source with energies from 5 keV to 100 keV for ionization chamber with 4 cm and 6 cm aperture radii by using the MCNP 4C code. The calculated scattering correction factors for 125I and 103Pd brachytherapy sources are 0.9987 and 0.9992, respectively and determined transmission correction is one for our free air ionization chamber of aperture radius 4 cm. cm.

351

CHEMICAL AND BIOLOGICAL AIR POLLUTANTS, AS PARAMETERS OF COMPLEX AIR QUALITY INDICES  

OpenAIRE

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...

TEKLA EÖTVÖS; LÁSZLÓ MAKRA

2007-01-01

352

Air pollution control escalate equipment costs  

International Nuclear Information System (INIS)

During fiscal year 1994, this author used the Bernard J. Steigerwald Opportunity for Independent Study, sponsored by US Environmental Protection Agency's Office of Air Quality Planning and Standards (Research Triangle Park, N.C.), to develop a group of quarterly indexes for adjusting or escalating air pollution control costs from one period to another. In all, nine indexes were developed, one equipment cost index (ECI) for each of nine control device categories. For convenience to the reader, additional indexes for two other equipment categories--available as part of the Producer Price Indexes compiled by the US Bureau of Labor Statistics--are also presented here. These 11 indexes--collectively known as the Vatavuk Air Pollution Control Cost Indexes (VAPCCI)--can be used to escalate costs from the initial (base) period (first quarter 1994) forward to any quarter in the future. To date, final indexes have been calculated (and are presented at the end of this article) for the second, third, and fourth quarters of 1994, and first quarter 1995; preliminary indexes are provided for second quarter 1995. Quarterly updates of these cost indexes will be computed as soon as the required input data become available. To date, no other set of cost indexes has been developed for such a wide array of pollution-control devices

353

Indoor Air  

Science.gov (United States)

Let's Talk about... INDOOR AIR When we talk about air pollution, we often think of smog, chemicals produced by factories or exhaust from cars. ... we breathe air that is in the room. Indoor air can become polluted, or spoiled, by adding harmful ...

354

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.nce 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)

355

Orbifold Index Cobordism Invariance  

CERN Document Server

We prove cobordism index invariance for transversally elliptic pseudo-differential operators associated to locally free actions of tori. This result implies index cobordism invariance for elliptic operators on orbifolds.

Farsi, C

2005-01-01

356

Dow Jones Internet Indexes  

Science.gov (United States)

Dow Jones Indexes has created the Dow Jones Internet Index (DJII) to bring "an ordered perspective" to "the seeming chaos of Internet stocks." The new index includes companies that generate a minimum of 50 percent of their revenues from the Internet. Complete documentation of DJII components, data, historical values, and news are provided on-site.

357

The Europe 2020 Index  

Science.gov (United States)

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…

Pasimeni, Paolo

2013-01-01

358

Air Pollution  

Science.gov (United States)

The Phoenix metropolitan area, like many large cities, has problems with air pollution at certain times of the year. You can do a simple experiment to determine some of the factors that affect air pollution.

Dr. Biology

359

Air Pollution.  

Science.gov (United States)

A summary of one of our most pressing environmental problems, air pollution, is offered in this book by the Director of Air Pollution Control for the Queensland (Australia) State Government. Discussion of the subject is not restricted to Queensland or Australian problems and policies, however, but includes analysis of air pollution the world over.…

Gilpin, Alan

360

Air Pressure  

Science.gov (United States)

In this experiment, learners use a blow dryer and water bottle to observe and record changes in air pressure caused by changes in temperature. Educators can use this activity to explain how changes in temperature cause changes in air pressure which cause wind. This activity guide contains background information on air pressure, instructions for an extension experiment, and links to useful online resources.

University of Illinois

2009-01-01

361

Monitoring of Air Polution by Using Fuzzy Logic  

OpenAIRE

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 o...

Dr. Gopal Upadhyaya,; Mr. Nilesh Dashore

2010-01-01

362

Assessment of effects of air pollution on the ring width of Japanese cedars (Cryptomeria Japonica D. Don) (1). Relationships between the operation of thermoelectric power stations and the fluctuations of the standardized ring index  

Energy Technology Data Exchange (ETDEWEB)

Effects of air pollution on ring width of cedar were investigated in the vicinity of thermoelectric power station, and correction method of climate conditions was studied. The investigation was conducted in Fukui Prefecture and samples were obtained at 1 meter height from ground. The sample was applied by soft-X ray apparatus and light absorbance of the image was measured. Fritts' method was applied to the result to obtain approximation of yearly-change pattern of ring width by exponential curve, and components of climate conditions and age of tree were separated by multiple regression analysis. As the consideration of the result, it was understood that, by operation of the power station, difference of environmental conditions by location for cedar growing were drastically changed. 22 refs., 6 figs., 2 tabs.

Kato, Terutaka; Kasuya, Minoru; Kagamimori, Sadanobu; Kawano, Shoichi; Kozuka, Hiroshi (Toyama Medical and Pharmaceutical Univ. (Japan); Kyoto Univ. (Japan); Toyama Medical and Pharmaceutical Univ. (Japan))

1988-12-20

363

Liberalizing air cargo services in APEC  

OpenAIRE

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...

Geloso Grosso, Massimo; Shepherd, Ben

2009-01-01

364

A Tourism Conditions Index  

OpenAIRE

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...

Chang, Chia-lin; Hsu, Hui-kuang; Mcaleer, Michael

2014-01-01

365

Eco-Index  

Science.gov (United States)

Eco-Index, a project of the Rainforest Alliance, is "a searchable almanac of current and past conservation projects in Mesoamerica, with project descriptions, goals, achievements, lessons learned, and more." With current, well-presented features covering a range of biodiversity conservation issues, Eco-Index offers an excellent way for conservation researchers and practitioners to keep abreast of activity in their field. Users are encouraged to add their own project descriptions to the Eco-Index database. Available in English or Spanish.

366

Human Development Index Data  

Science.gov (United States)

This data set traces the varying patterns of national progress in recent decades, documenting impressive long-term Human Development Index (HDI) gains even in most low-income countries. The data set also includes three innovative new measurements: the Inequality-adjusted Human Development Index (IHDI), the Gender Inequality Index (GII) and the Multidimensional Poverty Index (MPI). The data set is available in both CSV and SDMX file formats and contains more than 100 indicators that measure quality of life for all UN member states.

United Nations

367

Correcting the concentration index.  

Science.gov (United States)

In recent years attention has been drawn to several shortcomings of the Concentration Index, a frequently used indicator of the socioeconomic inequality of health. Some modifications have been suggested, but these are only partial remedies. This paper proposes a corrected version of the Concentration Index which is superior to the original Concentration Index and its variants, in the sense that it is a rank-dependent indicator which satisfies four key requirements (transfer, level independence, cardinal invariance, and mirror). The paper also shows how the corrected Concentration Index can be decomposed and generalized. PMID:18367273

Erreygers, Guido

2009-03-01

368

Air Travelers  

Science.gov (United States)

Offered by the Science Learning Network, the Air Travelers Web site is "an introduction to the basic principles of buoyancy, properties of gases, temperature, and the technology involved in hot air ballooning." Four activities are described along with any materials needed, directions, and questions that help students understand the concepts. A bonus activity is also provided that explains how to build your own hot air balloon using common household items.

1996-01-01

369

Hot Air  

Science.gov (United States)

In this activity, learners set up an experiment to investigate the effects of hot air on the path of a laser beam. They observe the wandering position of the laser beam spot on the wall after the light travels through hot air rising from the candle flame. Learners produce a table of observations from both the Cool Air and Hot Air experiments, and answer questions using evidence from their experiment. Apply what learners discover in this experiment to real-life by discussing why stars "twinkle."

The University of Texas McDonald Observatory

2011-01-01

370

A Ventilation Index for Tropical Cyclones  

OpenAIRE

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. T...

Tang, Brian; Emanuel, Kerry Andrew

2012-01-01

371

Does Indexing Exhaustively Matter?  

Science.gov (United States)

Experiments with two distinct collections, using three levels of indexing exhaustively for both documents and requests, show that substantially the same performance is obtained for very different levels of document indexing, if suitable choices are made of request level. (6 references) (Author)

Sparck Jones, Karen

1973-01-01

372

Concurrency Control for Adaptive Indexing  

CERN Document Server

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 ...

Graefe, Goetz; Idreos, Stratos; Kuno, Harumi; Manegold, Stefan

2012-01-01

373

Measuring environmental quality. An index of pollution  

International Nuclear Information System (INIS)

This paper develops an index of pollution based on the epidemiological dose-response function associated with each pollutant, and the welfare losses due to exposure to pollution. The probability of damage is translated into welfare losses, which provides the common metric required for aggregation. Isopollution surfaces may then be used to compare environmental quality over time and space. An Air Pollution Index (API) is computed using 1997 data for the criteria pollutants under the Clean Air Act (CAA). The results are compared with the EPA's Pollutant Standards Index (PSI). Two significant differences emerge: unlike the PSI, the API facilitates a detailed ranking of regions by air quality and API values may contradict PSI results. Some regions with PSI values of 100-200 are considered less polluted under the proposed methodology than those with PSI values between 50 and 100. The key reason for the difference is that PSI values are determined entirely by the gas with the highest relative concentration whereas the API value is based on the ambient concentrations of all pollutants. 14 refs

374

Air Pollution  

Science.gov (United States)

Students are introduced to the concept of air quality by investigating the composition, properties, atmospheric layers and everyday importance of air. They explore the sources and effects of visible and invisible air pollution. By learning some fundamental meteorology concepts (air pressure, barometers, prediction, convection currents, temperature inversions), students learn the impact of weather on air pollution control and prevention. Looking at models and maps, they explore the consequences of pollutant transport via weather and water cycles. Students are introduced to acids, bases and pH, and the environmental problem of acid rain, including how engineers address this type of pollution. Using simple models, they study the greenhouse effect, the impact of increased greenhouse gases on the planet's protective ozone layer and the global warming theory. Students explore the causes and effects of the Earth's ozone holes through an interactive simulation. Students identify the types and sources of indoor air pollutants in their school and home, evaluating actions that can be taken to reduce and prevent poor indoor air quality. By building and observing a few simple models of pollutant recovery methods, students explore the modern industrial technologies designed by engineers to clean up and prevent air pollution.

Integrated Teaching and Learning Program,

375

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

376

Dependence with air density of the response of the PTW SourceCheck ionization chamber for low energy brachytherapy sources  

Energy Technology Data Exchange (ETDEWEB)

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.

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

377

UV Index estimation from global radiation and total ozone observations in Azores  

OpenAIRE

The UV Index (UVI) is a public-oriented meteorological kind of information about the damaging ultraviolet radiation at the ground (Vaniceck et al., 1999). Its use begins to be so popular as temperatures highs, wind chill, fire risk index, air quality index and other meteorological indexes and parameters. A UVI scale was already defined by WHO (WHO, 2002) in order to provide a correspondence between UVI levels and protective measures to avoid damaging effects on humans. However, UVI is usually...

Carvalho, Fernanda; Henriques, Diamantino; Fialho, Paulo

2007-01-01

378

Recommended concentration limits of indoor air pollution indicators for requirement of acceptable indoor air quality  

Energy Technology Data Exchange (ETDEWEB)

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.

Wang, J.; Zhang, X. [Institute of HVAC and GAS Engineering, College of Mechanical Engineering, Tongji University, Shanghai 200092 (China)

2010-07-01

379

Recommended concentration limits of indoor air pollution indicators for requirement of acceptable indoor air quality  

Directory of Open Access Journals (Sweden)

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.

Wang J., Zhang X.

2010-07-01

380

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)

381

Air Quality  

Science.gov (United States)

The City of Albuquerque, New Mexico, offers a wide range of information about the factors that affect air quality and ways that people can improve it at this website. Users can find out facts on asbestos, radon, pollen, ozone, and temperature inversion. Visitors can discover the factors that influence ground level ozone development by choosing different weather conditions, emission levels, and populations in the interactive Smog City Simulator. The many requirements for the city presented at the website are a great way for users to learn how they can reduce air pollution. The website also presents data and information about the Tijeras/Roosevelt Middle School Ambient Air Monitoring Project.

382

The Index of Refraction  

Science.gov (United States)

In this media-rich lesson plan, students explore the refraction of light at the boundary between materials: they learn about the refractive indices of various materials and measure the index of refraction of plastic or gelatin.

WGBH Educational Foundation

2011-10-25

383

Cataloguing and Indexing Activities  

Science.gov (United States)

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)

Bakewell, K. G. B.

1971-01-01

384

CAD Centre - Index Searcher  

Science.gov (United States)

A searchable index of the CAD Centre, a postgraduate teaching and research unit in design manufacture and engineering management, with research focused on design methods and computer support of the design process for engineering applications.

385

Index of Refraction  

Science.gov (United States)

Refraction is an important behavior of light that can be used to explain the operation of lenses, prisms, and optical fiber, as well as natural phenomena such as rainbows and mirages. The index of refraction, or refractive index, is defined as the ratio of the speed of light in a vacuum to the speed of light in a material. The index of refraction is an important property of optical materials and one that can be easily measured in the laboratory.This lesson begins with a video that introduces the concept of refraction. Students learn firsthand how when a wave of light travels from one medium to another, the change in the wave's speed leads to a change in its wavelength and the bending of the wave. Next, students investigate index of refraction through an interactive media asset, research, and a class discussion. Following a video about the index of refraction and Snell's law, students work in groups to conduct their own laboratory experiment to measure the index of refraction of gelatin (or plastic).Note: This is the first of two optics lesson plans. You may want to follow this lesson with the Fiber Optics Lesson Plan.

386

Indexing Moving Points  

DEFF Research Database (Denmark)

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 inside R during a given time interval. A point can be inserted or deleted, or the trajectory of a point can be changed, in O(logB2 N) I/Os. Next, we present a general approach that improves the query time if the queries arrive in chronological order, by allowing the index to evolve over time. We obtain a tradeoff between the query time and the number of times the index needs to be updated as the points move. We also describe an indexing scheme in which the number of I/Os required to answer a query depends monotonically on the difference between the query time stamp t and the current time. Finally, we develop an efficient indexing scheme to answer approximate nearest-neighbor queries among moving points.

Agarwal, Pankaj K.; Arge, Lars Allan

2003-01-01

387

Air Abrasion  

Science.gov (United States)

... information you need from the Academy of General Dentistry Saturday, April 18, 2015 About | Contact InfoBites Quick ... general dentist, who has been trained in restorative dentistry techniques, will perform any procedures that use air- ...

388

Graded index porous optical fibers - dispersion management in terahertz range.  

Science.gov (United States)

A graded index porous optical fiber incorporating an air-hole array featuring variable air-hole diameters and inter-hole separations is proposed, fabricated, and characterized in a view of the fiber potential applications in low-loss, low-dispersion terahertz guidance. The proposed fiber features simultaneously low modal and intermodal dispersions, as well as low loss in the terahertz spectral range. We experimentally demonstrate that graded index porous fibers exhibit smaller pulse distortion, larger bandwidth, and higher excitation efficiency when compared to fibers with uniform porosity. PMID:25837124

Ma, Tian; Markov, Andrey; Wang, Lili; Skorobogatiy, Maksim

2015-03-23

389

Neural computing thermal comfort index for HVAC systems  

International Nuclear Information System (INIS)

The primary purpose of a heating, ventilating and air conditioning (HVAC) system within a building is to make occupants comfortable. Without real time determination of human thermal comfort, it is not feasible for the HVAC system to yield controlled conditions of the air for human comfort all the time. This paper presents a practical approach to determine human thermal comfort quantitatively via neural computing. The neural network model allows real time determination of the thermal comfort index, where it is not practical to compute the conventional predicted mean vote (PMV) index itself in real time. The feed forward neural network model is proposed as an explicit function of the relation of the PMV index to accessible variables, i.e. the air temperature, wet bulb temperature, globe temperature, air velocity, clothing insulation and human activity. An experiment in an air conditioned office room was done to demonstrate the effectiveness of the proposed methodology. The results show good agreement between the thermal comfort index calculated from the neural network model in real time and those calculated from the conventional PMV model

390

Determination of the air attenuation and electronic loss for the free air concentric cylinders ionization chamber; Determinacao da atenuacao do ar e perda eletronica para a camara de ionizacao de ar livre de cilindros concentricos  

Energy Technology Data Exchange (ETDEWEB)

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 (k{sub e}) and air attenuation (k{sub a}). 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)

Oliveira, Hebert Pinto Silveira de

2010-07-01

391

The Quilt Index  

Science.gov (United States)

With the goal of creating a single, comprehensive index to American quilts, the Quilt Index builds on the work of 4 state quilt documentation and digitization projects: the Michigan Quilt Project, Kentucky Quilt Project, Illinois Quilt Research Project, and Quilts of Tennessee (more information about these projects is at the site). Currently almost 900 quilt images and pieces of information are searchable in the Quilt Index. The project has established standards for data elements to be collected, and forms to facilitate the addition of quilt documentation from other states. Quilts dating from 1800 to 1999 can be searched by pattern name, quilter's name, location made, date, and collection or documentation project. Searches by pattern name (baby blocks, ocean waves, wedding ring) are possible, but the interface is quite picky about singular and plural. Several ways to browse are also available, such as by collection, period, and style/technique, or choose "view the entire index" to display 887 quilts and records. The Quilt Index is hosted by MATRIX, the humanities technology center at Michigan State University that also hosts H-Net, Humanities and Social Sciences OnLine.

392

UV (Ultraviolet) Index  

Science.gov (United States)

... useful tool for planning sun-safe outdoor activities. Ozone depletion, as well as seasonal and weather variations, cause ... menu Learn the Issues Air Chemicals and Toxics Climate Change Emergencies Greener Living Health and Safety Land and ...

393

Internet Corruption Perception Index  

Science.gov (United States)

The Internet Corruption Perception Index is provided by Transparency International and Goettingen University, Germany. The goal of the site to "rank countries by the extent of corruption in public administration." The ranking can then be used to help assess country risks. The Internet Corruption Perception Index is published annually and is based on "surveys undertaken by Gallup International, the World Competitiveness Yearbook, assessments by Political & Economic Risk Consultancy in Hong Kong, DRI/McGraw Hill Global Risk Service, Political Risk Services in Syracuse, USA, and data gathered from internet sources directly." The index for 1997 covers 52 countries, including both developed and developing countries. Recently added to the site is the report on the bribery propensity of leading exporting nations; this section investigates the "propensity to pay bribes for the acquisition of contracts in international trade." At the site, visitors can provide their own input on a country's bribery propensity.

394

Air surveillance  

Energy Technology Data Exchange (ETDEWEB)

This section of the 1994 Hanford Site Environmental Report summarizes the air surveillance and monitoring programs currently in operation at that Hanford Site. Atmospheric releases of pollutants from Hanford to the surrounding region are a potential source of human exposure. For that reason, both radioactive and nonradioactive materials in air are monitored at a number of locations. The influence of Hanford emissions on local radionuclide concentrations was evaluated by comparing concentrations measured at distant locations within the region to concentrations measured at the Site perimeter. This section discusses sample collection, analytical methods, and the results of the Hanford air surveillance program. A complete listing of all analytical results summarized in this section is reported separately by Bisping (1995).

Patton, G.W.

1995-06-01

395

Air surveillance  

International Nuclear Information System (INIS)

This section of the 1994 Hanford Site Environmental Report summarizes the air surveillance and monitoring programs currently in operation at that Hanford Site. Atmospheric releases of pollutants from Hanford to the surrounding region are a potential source of human exposure. For that reason, both radioactive and nonradioactive materials in air are monitored at a number of locations. The influence of Hanford emissions on local radionuclide concentrations was evaluated by comparing concentrations measured at distant locations within the region to concentrations measured at the Site perimeter. This section discusses sample collection, analytical methods, and the results of the Hanford air surveillance program. A complete listing of all analytical results summarized in this section is reported separately by Bisping (1995)

396

Fiber optic refractive index monitor  

Science.gov (United States)

A sensor for measuring the change in refractive index of a liquid uses the lowest critical angle of a normal fiber optic to achieve sensitivity when the index of the liquid is significantly less than the index of the fiber core. Another embodiment uses a liquid filled core to ensure that its index is approximately the same as the liquid being measured.

Weiss, Jonathan David (Albuquerque, NM)

2002-01-01

397

Student Derived KP Index  

Science.gov (United States)

This is an activity about the Kp index, a quantification of fluctuations in the Earth's magnetic field due to the relative strength of a magnetic storm. Learners will take a reading from a magnetometer site and make a Kp index estimate to predict whether or not an aurora display will occur near that site. This resource is designed to support student analysis of THEMIS (Time History of Events and Macroscale Interactions during Substorms) Magnetometer line-plot data. This activity requires the use of a computer with Internet access. This is activity 18 in Exploring Magnetism: Earth’s Magnetic Personality.

398

Schmidt Sting Pain Index  

Science.gov (United States)

This Wikipedia page has the cleanest version of the Schmidt Sting Pain Index I've seen online. Justin O. Schmidt created this index after years of work with Hymenoptera, and relates his vast experience with their venom to a scale that can be understood by all. The page has only a few references, but one of those will take you to Christ Starr's four stage sting pain scale. At the top of the scale are bullet ants, and pepsis wasps, at the bottom are sweat bees and fire ants.

0000-00-00

399

CHEMICAL AND BIOLOGICAL AIR POLLUTANTS, AS PARAMETERS OF COMPLEX AIR QUALITY INDICES  

Directory of Open Access Journals (Sweden)

Full Text Available 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 aspects of the data can be lost. All known indices contain only chemical pollutants, while certain biological pollutants can enhance the effects of the chemical pollutants and vice versa. In this paper we discuss the importance of integrating biological pollutants into air quality indices. In order to increase efficacy of these indices to the civil society we aim to introduce geographic information system (GIS methods into publishing air quality information.

TEKLA EÖTVÖS

2007-12-01

400

Gradient Refractive Index Lenses.  

Science.gov (United States)

Describes the nature of gradient refractive index (GRIN) lenses, focusing on refraction in these materials, focal length of a thin Wood lens, and on manufacturing of such lenses. Indicates that GRIN lenses of small cross section are in limited production with applications suggested for optical communication and photocopying fields. (JN)

Morton, N.

1984-01-01

401

Divisia Monetary Index  

OpenAIRE

This short paper is the first draft of an encyclopedia entry on Divisia Monetary Indexes to appear in the second edition of the International Encyclopedia of the Social Sciences. The encyclopedia is edited by William A. Darity and forthcoming from Macmillan Reference USA (Thomson Gale).

Barnett, William A.

2006-01-01

402

A Social Capital Index  

Science.gov (United States)

We define an index of social capital using game-theoretical concepts. We assume that interests of individuals are presented by means of a cooperative game which take into account possible different players abilities whereas the network of relations is modeled by a graph. The social capital of each actor is then measured as the difference between his Myerson value and his Shapley value.

Gonzàlez-Aranguena, Enrique; Khmelnitskaya, Anna; Manuel, Conrado; del Pozo, Mónica

2011-09-01

403

On indexed actions  

CERN Document Server

We present some laws relating the $\\Cat$-indexed categories of left, right and bi-actions: by defining $(A\\comp M)x = Mx^{Ax}$ one gets a biclosed monoidal action of $\\Set^{X\\op}$ on $(\\Set^X)\\op$, while $\\B X$ and $\\Cat/X$ act (partially) on their opposites by exponentials; both the inclusions $(\\B X,\\B X)\\to (\\Set^{X\\op},\\Set^X) \\to (\\Cat/X,\\Cat/X)$ preserve the (cartesian) monoidal structures and the actions, and the same holds for substitutions along functors. These strong morphisms of strong indexed monoidal actions have in fact a wider range of applications; in particular, replacing $\\Set$ with any (co)complete symmetric monoidal closed category $\\V$, we consider the pair of indexed categories $(\\V_0^{X\\op},\\V_0^X ; X\\in\\Cat)$ with the pair of biclosed indexed monoidal actions of each one on the opposite of the other one and its formal relationships with biactions and constant actions. Some of the resulting laws also hold in a fragment of biclosed bicategory (with an object supporting a symmetric monoid...

Pisani, Claudio

2012-01-01

404

The Index House  

International Nuclear Information System (INIS)

This paper reports on the Pennsylvania Radon Research and Demonstration Project. The project involved the monitoring of the Index House for indoor radon, and was one of the earliest programs involving indoor radon contamination. The history of the house, the investigation, and testing and remediation procedures are discussed

405

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.

406

/Air Atmospheres  

Science.gov (United States)

Molten magnesium oxidizes rapidly when exposed to air causing melt loss and handling difficulties. The use of certain additive gases such as SF6, SO2, and CO2 to form a protective MgO layer over a magnesium melt has been proposed. The oxidation behavior of molten magnesium in air containing various concentrations of SF6 was investigated. Measurements of the kinetics of the oxide layer growth at various SF6 concentrations in air and temperatures were made. Experiments were performed using a thermogravimetric analysis unit in the temperature range of 943 K to 1043 K (670 °C to 770 °C). Results showed that a thin, coherent, and protective MgF2 layer was formed under SF6/Air mixtures, with a thickness ranging from 300 nm to 3 ?m depending on SF6 concentration, temperature, and exposure time. Rate parameters were calculated and a model for the process was developed. The morphology and composition of the surface films were studied using scanning electron microscope and energy-dispersive spectroscope.

Emami, Samar; Sohn, Hong Yong; Kim, Hang Goo

2014-08-01

407

Air quality  

International Nuclear Information System (INIS)

This chapter of the 'Assessment of the state of the environment in Lebanon' describes the air quality and identifies the most important air quality issues. Baseline information about the factors affecting dispersion and the climate of Lebanon presents as well and overall estimation of total emissions in Lebanon. Emissions from vehicles, electricity and power plants generation are described. Industrial emitters of air pollutants are described for each kind of industry i.e.cement plants, Selaata fertilizer factory, sugar-beet factory, refineries and for those derived from the use of leaded fuel . Impact of economic and human activities on air quality in Lebanon (especially in Beirut and Tripoli) are quantified by quantities of CO2, SO2, NOx, total suspended particulates(TSP), deposition and their environmental effects on health. In abscence of emissions monitoring, data available are expressed in terms of fuel use, output and appropriate empirical factors, national output and workfores sizes. Finally key issues and some potential mitigation /management approaches are presented

408

Scientific Journal Indexing  

Directory of Open Access Journals (Sweden)

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.

Getulio Teixeira Batista

2007-08-01

409

Determining the Thickness and Refractive Index of a Mirror  

Science.gov (United States)

When a laser beam reflects from a back surface glass mirror and falls on a screen, a pattern of discrete bright spots is created by partial reflection and refraction of the light at the air-glass interface and reflection at the mirror surface (Fig. 1). This paper explains how this phenomenon can be used to determine the refractive index and the…

Uysal, Ahmet

2010-01-01

410

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)

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.

Marisa, Estarlich; Carmen, Iñiguez; Ana, Esplugues; Enrique, Mantilla; Òscar, Zurriaga; Andreu, Nolasco; Ferran, Ballester.

2013-04-01

411

Influence of local air velocity from air conditioner evaluated by salivary and skin biomarkers  

Energy Technology Data Exchange (ETDEWEB)

The purpose of this paper is to reveal both the psychosomatic and the physical effects of local air velocity from an air conditioner using biomarkers which can be collected noninvasively. Salivary {alpha}-amylase activity (SAA) and salivary cortisol were used as the indexes of psychosomatic effects. The total protein (TP) collected from stratum corneum was used as an index of the physical condition of dry skin. A continuous experiment over a 5 days period in summer was conducted using 8 healthy young male adults for 2-types of airflow conditioners, a whole ceiling-type air conditioner (without local air velocity) and a normal-type air conditioner (with local air velocity). The subjects felt cool, windy, dry and uncomfortable when under the normal-type air conditioner as determined in a subjective evaluation. The SAA under the normal-type air conditioner fluctuated more widely than with the whole ceiling-type air conditioner. The level of salivary cortisol decreased more in a day under the normal-type air conditioner than with the whole ceiling-type air conditioner. These results showed that reducing local air velocity may provide more healthy psychosomatic conditions over the long-term. Moreover, the TP of a drying-exposed skin area showed a significant change during this experiment whereas the TP of drying-protected area was relatively unchanged. It was indicated that one week's exposure to local air velocity conditions possibly influences the drying of facial skin. Thus, air movement at low velocity can be provides more comfortable conditions not only psychosomatically but also physically. (author)

Yamaguchi, Masaki; Takahashi, Takayuki; Yoshino, Yuichiro; Sasaki, Makoto [Graduate School of Engineering, Iwate University, 4-3-5 Ueda, Morioka 020-8551 (Japan); Nishimiya, Hajime [Asahi Kasei Homes Corporation, R and D Laboratories, 2-1 Samejima, Fuji, Shizuoka 416-8501 (Japan)

2010-11-15

412

Evaluation of a energy consumption index for commercial buildings in Brazil  

Energy Technology Data Exchange (ETDEWEB)

The present paper proposes a energy consumption index for commercial buildings located in four different Brazilian climates. For such evaluations, the building simulation tool EnergyPlus was used and a sensitivity analysis was made for some of the main parameters of an air-conditioned building. The analysis showed that the electrical power and lighting density as well as the COP of the air conditioning system promotes the higher variations on the proposed energy index. (author)

Silva, Jose Eduardo Correa Santana; Hernandez Neto, Alberto [Universidade de Sao Paulo (EP/USP), SP (Brazil). Escola Politecnica], Emails: jose.edu@gmail.com, ahneto@usp.br

2010-07-01

413

Inhalation dose due to presence of 131I in air above septic tank system of an endocrinology hospital  

International Nuclear Information System (INIS)

We present here measurements of the 131I concentration for both: Gaseous and aerosol fraction of 131I in the air above the septic tank containing wastes from medical application of this isotope. Aerosols were collected using air filters, whereas gaseous forms of iodine were trapped in KI impregnated charcoal double layer cartridge. Besides an active method (pumping of the air through system of filters) an attempt for using a passive method (charcoal traps) for monitoring of radio-iodine is described. For better characterisation of a site the external kerma was determined by means of G - M and TLD techniques as well as the activity kept in the septic tank was measured by gamma spectrometry. Results show that the activity of the aerosol fraction can be neglected compared to that of the gaseous fraction. He measured activity of air is low, on the level of 1 Bq m-3, even during simulated failure of the ventilation system. Estimated inhalation dose for the serviceman of septic tanks is low (?10%) compared with external dose obtained by such person due to gamma radiation from the tank (on the level ?500 nSv h-1). Therefore, the concept of passive monitoring of the iodine in air was abandoned. Also estimated is the efficiency of 131I reduction by a charcoal filter of the ventilation system and 131I input to the environment by the ventilation chimney. (authors)

414

'76 EQ Index  

Science.gov (United States)

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 pessimi