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1

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)

2008-01-01

2

Air-kerma cavity standards  

International Nuclear Information System (INIS)

This paper reviews the current status of air-kerma cavity standards for gamma rays from 60Co, 137Cs and 192Ir sources. It describes the basic principles and the theories to determine the air-kerma rate from the ionization current of graphite-walled cavity ionization chambers. A typical design of a cavity chamber is shown and described. The various correction factors to be applied to the standards and their determination by experimental and Monte Carlo methods are discussed. A typical uncertainty budget for a cavity standard is presented and the results of comparisons between primary standards are summarized and discussed. Finally, conclusions are drawn and proposals made for topics to be addressed in future studies. (authors)

2009-04-01

3

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)

2013-01-01

4

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

5

Air kerma rates measurement in an interventional cardiology suite  

International Nuclear Information System (INIS)

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

2010-05-01

6

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

2002-11-25

7

Air Kerma above environmental radiometric calibration facility for field equipment  

International Nuclear Information System (INIS)

The use of gamma ray spectrometers broadened the aims of gamma ray surveys, stead of measuring only the gross radiation, as was done with the GM tubes, it is now possible to be used for uranium exploration, geological mapping as an aid to the exploration of non radioactive ores like gold and tin, radiation background measurements to identify hot spots for radiation hazard evaluation and environmental monitoring of fallout from radiological and nuclear accidents. It became necessary to carefully and precisely calibrate the field equipment to be used to get all the information from such uses. There is an environmental radiometric calibration facility for field equipment, consisting of eight radioactive concrete sources, at the Institute of Radioprotection and Dosimetry - IRD (CNEN/Brazil). These sources are cylindrical with 3 m diameter, 0.5 m thick and weigh about 7.5 tons each. The amount and type of the radioactive material, 238 U and 232 Th and 40 K ores in secular radioactive equilibrium, added to the concrete to simulate rock outcrops, varies in order to obtain different gamma fields, varying in both energy and intensity. These different radiation fields were measured with a HPGe portable detector, specifically calibrated for spectrum stripping, and the air kerma energy distribution was determined for each concrete source and compared with the total air kerma calculated from the nuclide concentration and by others radiometric methods. (author)

2000-10-15

8

Computation of air kerma rate around an industrial radiography source  

International Nuclear Information System (INIS)

Use of Iridium-192 and Cobalt-60 sources in Industrial Radiography has recorded a steep rise in the last three decades in India. There are about 425 institutions in possession of 1100 radiography equipment's. Widespread use of these sources call for meticulous radiation safety programme in the use of these sources. A gamma radiography exposure device comprises of adequately shielded source holder assembly and accessories such as remote control cable and guide tube with suitable mechanism to facilitate radiation exposure in a safe manner for industrial radiography work. The source holder assembly is driven out of the shielded container through the guide tube by means of a suitable drive mechanism. Various built-in design safety features are incorporated in these devices to ensure safe operation and to avoid untoward incidents. In spite of effective regulatory control, accidents may take place. For example, an accident situation may arise due to decoupling of the source assembly which may lead to the source falling on the ground and consequent exposure of people around the source and also the personnel involved in source retrieval operations. A knowledge of the air kerma distribution around the source will be of use in estimating the doses to the concerned personnel. This paper discusses the air kerma distribution around and iridium-192 radiography source computed using Monte Carlo method

2001-12-01

9

Air kerma based dosimetry calibration for the Leksell Gamma Knife  

Energy Technology Data Exchange (ETDEWEB)

No accepted official protocol exists for the dosimetry of the Leksell Gamma Knife registered (GK) stereotactic radiosurgery device. Establishment of a dosimetry protocol has been complicated by the unique partial-hemisphere arrangement of 201 individual {sup 60}Co beams simultaneously focused on the treatment volume and by the rigid geometry of the GK unit itself. This article proposes an air kerma based dosimetry protocol using either an in-air or in-acrylic phantom measurement to determine the absorbed dose rate of fields of the 18 mm helmet of a GK unit. A small-volume air ionization chamber was used to make measurements at the physical isocenter of three GK units. The absorbed dose rate to water was determined using a modified version of the AAPM Task Group 21 protocol designed for use with {sup 60}Co-based teletherapy machines. This experimentally determined absorbed dose rate was compared to the treatment planning system (TPS) absorbed dose rate. The TPS used with the GK unit is Leksell GammaPlan. The TPS absorbed dose rate at the time of treatment is the absorbed dose rate determined by the physicist at the time of machine commissioning decay corrected to the treatment date. The TPS absorbed dose rate is defined as absorbed dose rate to water at the isocenter of a water phantom with a radius of 8 cm. Measurements were performed on model B and C Gamma Knife units. The absorbed dose rate to water for the 18 mm helmet determined using air-kerma based calculations is consistently between 1.5% and 2.9% higher than the absorbed dose rate provided by the TPS. These air kerma based measurements allow GK dosimetry to be performed with an established dosimetry protocol and without complications arising from the use of and possible variations in solid phantom material. Measurements were also made with the same ionization chamber in a spherical acrylic phantom for comparison. This methodology will allow further development of calibration methods appropriate for the smaller fields of GK units to be compared to a well established standard.

Meltsner, Sheridan Griffin; DeWerd, Larry A. [Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)

2009-02-15

10

Air kerma based dosimetry calibration for the Leksell Gamma Knife  

International Nuclear Information System (INIS)

No accepted official protocol exists for the dosimetry of the Leksell Gamma Knife registered (GK) stereotactic radiosurgery device. Establishment of a dosimetry protocol has been complicated by the unique partial-hemisphere arrangement of 201 individual 60Co beams simultaneously focused on the treatment volume and by the rigid geometry of the GK unit itself. This article proposes an air kerma based dosimetry protocol using either an in-air or in-acrylic phantom measurement to determine the absorbed dose rate of fields of the 18 mm helmet of a GK unit. A small-volume air ionization chamber was used to make measurements at the physical isocenter of three GK units. The absorbed dose rate to water was determined using a modified version of the AAPM Task Group 21 protocol designed for use with 60Co-based teletherapy machines. This experimentally determined absorbed dose rate was compared to the treatment planning system (TPS) absorbed dose rate. The TPS used with the GK unit is Leksell GammaPlan. The TPS absorbed dose rate at the time of treatment is the absorbed dose rate determined by the physicist at the time of machine commissioning decay corrected to the treatment date. The TPS absorbed dose rate is defined as absorbed dose rate to water at the isocenter of a water phantom with a radius of 8 cm. Measurements were performed on model B and C Gamma Knife units. The absorbed dose rate to water for the 18 mm helmet determined using air-kerma based calculations is consistently between 1.5% and 2.9% higher than the absorbed dose rate provided by the TPS. These air kerma based measurements allow GK dosimetry to be performed with an established dosimetry protocol and without complications arising from the use of and possible variations in solid phantom material. Measurements were also made with the same ionization chamber in a spherical acrylic phantom for comparison. This methodology will allow further development of calibration methods appropriate for the smaller fields of GK units to be compared to a well established standard.

2009-02-01

11

Review of requirements for a primary standard of air kerma for {sup 60}Co and {sup 137}Cs {gamma}-rays at protection level air kerma rates  

Energy Technology Data Exchange (ETDEWEB)

The three cavity chambers which comprise the primary standard of air kerma for {sup 60}Co and {sup 137}Cs {gamma}-rays are reaching the end of their working life. A new primary standard suitable for use at protection level air kerma rates is proposed to replace them and the main parameters which must be addressed in the design are identified. Recommendations are made for further work needed to inform the design process. (author)

Angliss, R.; Moretti, C

2000-03-01

12

Influence of atmospheric rainfall to ? radiation Kerma rate in surface air  

International Nuclear Information System (INIS)

Objective: To investigate the influence rule of the atmospheric Rainfall to the ? radiation Kerma rate in surface air in order to revise the result of its measurement during rainfall. Methods: The influence factors of rainfall to the measurement of the ? radiation Kerma rate in air were analyzed and then the differential equation of the correlation factors was established theoretically, and by resolving the equation, the mathematical model Was obtained. The model was discussed through several practical examples. Results: The mathematical model was coincided with the tendency of curve about the measured data on the influence rule of rainfall to the ? radiation Kerma rate in surface air. Conclusion: By using the theoretical formula in this article which is established to explain the relationship between the rainfall and the ? radiation Kerma rate in surface air, the influence of rainfall to the ? radiation Kerma rate in surface air could be correctly revised. (authors)

2009-04-01

13

Seasonal variation of air kerma rate in Sicily  

International Nuclear Information System (INIS)

Thermoluminescence dosimetry has been used to measure air kerma in 29 sites in Sicily. Four three month measurement campaigns have been carried out in order to assess seasonal variations. Average annual values between 20 and 90 nGy h-1, after cosmic background subtraction, are reported. Average annual values are strongly dependent on site lithology, and we find that winter data are generally the highest, while spring and autumn rates are generally the lowest with very similar trends in any site. Summer values generally lay in between. Largest seasonal variations are found in sites along the southern coast of the island, probably because of stronger action of winds affecting radon, along with its progeny, concentrations at ground level

2008-07-01

14

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

15

Corrections to air kerma rate measurements of 125I brachytherapy sources to free space conditions  

International Nuclear Information System (INIS)

Air kerma rate measurements have been made between 40 cm and 100 cm from one of a set of 125I reference sources within the facilities of Amersham International plc. Monte Carlo techniques have been used to calculate the air kerma rate components over the same range of distances from this source. After comparing the calculated data with measurements, the compliance of the data with the inverse square law was investigated, and corrections were derived to obtain the air kerma rate at 1 m in free space from each source. Simulations of the experimental setup with an isotropic monoenergetic point source close to the effective energy of 125I were found to reproduce the air kerma rate measurements reasonably accurately, and indicated that the contribution due to scattered photons was significant. The overall correction (which is defined as the product of individual corrections for chamber size effect, air attenuation and radiation scatter) required to the inverse square law to obtain the air kerma rate at 1 m in free space was found to be 0.981, 0.984 and 0.980, respectively, for air kerma rate measurements at 40 cm, 60 cm and 100 cm from the 125I reference source. The total uncertainty in these corrections was estimated to be 0.88% at the 1? level. (author)

1994-01-01

16

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)

1997-06-03

17

Calibration of Ionization Chambers for Measuring Air Kerma Integrated over Beam Area in Diagnostic Radiology  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The air kerma area product PKA is an important quantity used by hospital physicists in quality assurance and optimization processes in diagnostic radiology and is recommended by national authorities for setting of diagnostic reference levels. PKA can be measured using a transmission ionization chamber (kerma area product (KAP) meter) mounted on the collimator housing. Its signal QKAP must be calibrated to give values of PKA. The objective of this thesis is to analyze the factors influencing t...

Larsson, Peter

2006-01-01

18

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

19

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 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.

2010-06-07

20

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

 
 
 
 
21

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

Energy Technology Data Exchange (ETDEWEB)

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.

Kwon, Deukwoo; Little, Mark P.; Miller, Donald L. [Radiation Epidemiology Branch, National Cancer Institute, Division of Cancer Epidemiology and Genetics, Bethesda, Maryland 20852-7238 (United States); Radiation Epidemiology Branch, National Cancer Institute, Division of Cancer Epidemiology and Genetics, Bethesda, Maryland 20852-7238 and Department of Radiology and Radiological Sciences, F. Edward Hebert School of Medicine, Uniformed Services University, Bethesda, Maryland 20814 (United States)

2011-07-15

22

Quality assurance of air kerma strength for Ir-192 high dose rate source  

International Nuclear Information System (INIS)

AAPM TG43 report has recommended to measure air kerma strength with the strength of source. Main purpose of this study is to verify the accuracy of air kerma strength provided by manufacturer. Materials for this study were MAX-4001 Electrometer, HDR 1000 Plus of the corporation of standard imaging, and 6 french bronchial Applicator with 1000 mm. We measured ionization current in 10-90 mm range from the bottom of the central axis of chamber. The reference point of calibration displayed by the maximum ionization current in the ionization current curve was measured, and air kerma strength was computed from the maximum ionization current. We acquired 50 mm distance to correspond with the maximum ionization current in the ionization current curve. Its distance has perfectly fitted to the source reference point of calibration certificate of UW-ADCL. Air kerma strength computed value has measured about 0.5% more than calibration value provided by manufacturer. Air kerma strength of calibration certificate provided by manufacturer has acquired reliable results. This study shows that considering the move error of dwell position of source and the dead space length in well-type chamber is a good way to get an accurate result

2007-06-01

23

X-rays spectrum and air Kerma during a mammography study  

International Nuclear Information System (INIS)

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

2009-10-02

24

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

2008-06-01

25

Air-kerma determination using a variable-volume cavity ionization chamber standard  

International Nuclear Information System (INIS)

A graphite-walled cavity ionization chamber of modular design and variable volume has been used to determine the air-kerma rate in the reference 60Co field at the BIPM. The chamber can be configured in five sizes. High-accuracy mechanical measurements of the volume of the air cavity were made for each configuration using a co-ordinate measuring machine. Ionization current measurements were made for each configuration and corrected for the effects of ion recombination and diffusion, stem scatter and chamber orientation. Monte Carlo calculations of cavity dose were made to evaluate the correction factors kwall and kan. A reproducibility of the ionization current per mass of 1.5 parts in 104 was achieved on the repeated assembly of each configuration. The results show an air-kerma rate determination that increases with volume, the total change being around 8 parts in 104. When analysed differentially, the air-kerma rate relative to the BIPM standard is Kdiff/KBIPM = 1.0026(6). A detailed uncertainty budget is presented. Possible reasons for the observed behaviour are discussed that might have consequences for all existing standards for air-kerma

2007-12-07

26

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

27

Ratios of effective dose to entrance skin dose to the air kerma for some medical sources.  

Science.gov (United States)

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) u...

K. N. Wise

1998-01-01

28

Air kerma strength characterization of a GZP6 Cobalt-60 brachytherapy source  

Science.gov (United States)

Background Task group number 40 (TG-40) of the American Association of Physicists in Medicine (AAPM) has recommended calibration of any brachytherapy source before its clinical use. GZP6 afterloading brachytherapy unit is a 60Co high dose rate (HDR) system recently being used in some of the Iranian radiotherapy centers. Aim In this study air kerma strength (AKS) of 60Co source number three of this unit was estimated by Monte Carlo simulation and in air measurements. Materials and methods Simulation was performed by employing the MCNP-4C Monte Carlo code. Self-absorption of the source core and its capsule were taken into account when calculating air kerma strength. In-air measurements were performed according to the multiple distance method; where a specially designed jig and a 0.6 cm3 Farmer type ionization chamber were used for the measurements. Monte Carlo simulation, in air measurement and GZP6 treatment planning results were compared for primary air kerma strength (as for November 8th 2005). Results Monte Carlo calculated and in air measured air kerma strength were respectively equal to 17240.01 ?Gym2 h?1 and 16991.83 ?Gym2 h?1. The value provided by the GZP6 treatment planning system (TPS) was “15355 ?Gym2 h?1”. Conclusion The calculated and measured AKS values are in good agreement. Calculated-TPS and measured-TPS AKS values are also in agreement within the uncertainties related to our calculation, measurements and those certified by the GZP6 manufacturer. Considering the uncertainties, the TPS value for AKS is validated by our calculations and measurements, however, it is incorporated with a large uncertainty.

Toossi, Mohammad Taghi Bahreyni; Ghorbani, Mahdi; Mowlavi, Ali Asghar; Taheri, Mojtaba; Layegh, Mohsen; Makhdoumi, Yasha; Meigooni, Ali Soleimani

2010-01-01

29

Comparison of two different methods to determine the air kerma calibration factor, Nk, for 192Ir  

International Nuclear Information System (INIS)

Two different methods to determine the air kerma calibration factor for 192Ir high dose rate sources are described. One method is used by the Nederlands Meetinstituut (NMi), the national standards institute of the Netherlands, and is based on weighting the response curve of an ionization chamber over the 192Ir spectrum. Another method was developed by Goetsch et al. and is based on the determination of the absorption in the chamber wall for 192Ir and air kerma calibration factors for a 250 kV X ray quality and 137Cs gamma rays. The difference between both methods is discussed in the paper. A description of the NMi method is given. (author)

2003-12-01

30

Experimental verification of the air kerma to absorbed dose conversion factor C_w_,_u  

International Nuclear Information System (INIS)

In a recently published code of practice for the dosimetry of high-energy photon beams, the absorbed dose to water is determined using an ionization chamber having an air kerma calibration factor and applying the air kerma to absorbed dose conversion factor C_w_,_u. The consistency of these C_w_,_u values has been determined for four commonly employed types of ionization chambers in photon beams with quality varying between "6"0Co gamma-rays and 25 MV X-rays. Using a graphite calorimeter, C_w_,_u has been determined for a graphite-walled ionization chamber (NE 2561) for the same qualities. The values of C_w_,_u determined with the calorimeter are within the experimental uncertainty equal to C_w_,_u values determined according to any of the recent dosimetry protocols. (Auth.)

1987-01-01

31

Comparison of the standards of air kerma of the NCM Bulgaria and the BIPM for {sup 60}Co {gamma} rays  

Energy Technology Data Exchange (ETDEWEB)

A comparison of the standards of air kerma of the National Center of Metrology (NCM) and of the Bureau International des Poids et Mesures (BIPM) has been carried out in {sup 60}Co radiation. It shows that the ratio of the NCM and BIPM standards is 1.0117 with a relative standard uncertainty of 1.9 x 10{sup -3}. This is the first comparison of air kerma standards of the NCM with the BIPM. (authors)

Allisy-Roberts, P.J.; Burns, D.T. [Bureau International des Poids et Mesures (BIPM), 92 - Sevres (France); Kessler, C. [Centro Regional de Referencia para Dosimetria, Buenos Aries (Argentina); Ivanov, R.N. [National Center of Metrology, Sofia (Bulgaria)

2002-03-15

32

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

International Nuclear Information System (INIS)

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

2013-06-01

33

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

34

X-Rays spectrum and air kerma during a mammography study  

International Nuclear Information System (INIS)

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

2009-07-05

35

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

36

Study of the indirect calibration of clinical air kerma-area meters; Estudo da calibracao indireta de medidores clinicos do produto kerma-area  

Energy Technology Data Exchange (ETDEWEB)

Kerma-area product (P{sub KA}) is a quantity which is independent of the distance to the X-ray tube focal spot and that can be used to assess the effective dose in patients. Clinical P{sub KA} meters are usually calibrated on-site by measuring the air kerma with an ion chamber and evaluating the irradiated area by means of a radiographic image. This work presents a preliminary metrological evaluation of the calibration of a device marketed recently (PDC, Patient Dose Calibrator, Radcal), designed for calibrating clinical P{sub KA} meters. Results are also shown of applying the PDC to the cross calibration of a clinical P{sub KA} meter from a radiology equipment. Results confirm a lower energy dependence of the PDC relative to the tested clinical meter. (author)

Almeida Junior, Jose N. [Pontificia Univ. Catolica de Sao Paulo (PUC/SP), SP (Brazil). Curso de Fisica Medica; Silva, Marcia C. [Hospital Israelita Albert Einstein (HIAE), Sao Paulo, SP (Brazil); Terini, Ricardo A., E-mail: rterini@pucsp.b [Pontificia Univ. Catolica de Sao Paulo (DF/PUC/SP), SP (Brazil). Dept. de Fisica; Herdade, Silvio B. [Universidade de Sao Paulo (IEE/USP), SP (Brazil). Inst. de Eletrotecnica e Energia. Secao Tecnica de Desenvolvimento Tecnologico em Saude Marco A.G. Pereira

2011-07-01

37

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.

38

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2009-10-15

39

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

2001-11-26

40

Comparison of the standards for air kerma of the NPL and the BIPM for 60Co ? rays  

International Nuclear Information System (INIS)

An indirect comparison of the standards for air kerma of the National Physical Laboratory (NPL), United Kingdom and of the Bureau International des Poids et Mesures (BIPM) was made in 60Co gamma radiation in September 2007. The comparison result, based on the calibration coefficients for two transfer chambers and expressed as a ratio of the NPL and the BIPM standards for air kerma, is 1.0011 (0.0038). The degrees of equivalence between the NPL 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)

2010-02-01

 
 
 
 
41

A secondary air kerma strength standard for Yb-169 interstitial brachytherapy sources.  

Science.gov (United States)

Ytterbium-169 (169Yb) is a promising new intermediate low-energy isotope for interstitial implantation. To date, no air kerma strength (SK) standard for this source exists that can serve as a sound foundation for comparing various dose measurements and theoretical calculations. We have solved this problem by adapting the free air measurement technique of Goetsch et al, originally developed for 192Ir. Using a 100 cm3 spherical ion chamber with NIST traceable external beam calibrations in a free air geometry, we have measured the air kerma strength of six different source batches (two type 6 batches, three type 8 batches, and one experimental high-intensity source). Room scatter corrections, derived from an empirical fit to the data (following Goetsch et al) and/or directly by Monte Carlo simulation, yielded identical results with a reproducibility of 1%. The ratio [SK/Avendor] of measured SK to the vendor's contained activity assay averaged 1.554 cGy cm2 mCi-1 h-1 (0.0420 microGy m2 MBq-1 h-1), in conflict with the expected value of 1.34 (0.0362), derived from Monte Carlo calculations. The measured [SK/Avendor] for the type 8 seeds varies by as much as 10% whereas the SK/dose calibrator reading ratio varies by no more than 0.3%, suggesting that the reproducibility of Avendor is relatively poor. These discrepancies may help explain the variation (as large as 28%) in published dose rate constants for 169Yb. PMID:7652005

Das, R K; Mishra, V; Perera, H; Meigooni, A S; Williamson, J F

1995-05-01

42

[Measurement of the air kerma using dosimeters embedded in an acrylic phantom in interventional radiology.].  

Science.gov (United States)

Interventional radiology procedure guidelines and a measurement manual (IVR guidelines) have been published for the maintenance of interventional equipment with an objective of avoiding serious radiation-induced skin injuries. In the IVR guidelines, the positioning of a dosimeter at the interventional reference point is determined, whereas placement of a phantom is not specified. Therefore, the phantom is placed at any convenient location between the dosimeter and image intensifier. The space around the dosimeter reduces detection of scattered radiation. In this study, dosimeters (consisting of a parallel plate ionization chamber, glass dosimeter and OSL dosimeter) were embedded in the phantom surface to detected scattered radiation accurately. As a result, when dosimeters were embedded in the phantom surface, the air kerma was increased compared with that when dosimeters were placed on the phantom. This suggested that embedded dosimeters were able to detect scattered radiation from the phantom. PMID:16788288

Kawabe, Atsushi; Shibuya, Koichi; Takeda, Yoshihiro

2006-01-01

43

The correlation of air kerma-area product with staff dose in fluoroscopy  

International Nuclear Information System (INIS)

Radiation doses to staff who perform fluoroscopy can be relatively high compared with other occupationally exposed individuals working in diagnostic radiology and may approach a dose limit or constraint if their workload is high. It is therefore important to be able to monitor and predict radiation doses to staff performing fluoroscopy. Scattered radiation distributions in the vicinity of the patient couch were measured for simulations of both overcouch X-ray tube/undercouch image intensifier and undercouch X-ray tube/overcouch image intensifier fluoroscopy for a wide range of tube potentials (50-110 kV). An experimental arrangement realistic of clinical practice was set up. The effect of field size and focus skin distance was also studied. It was discovered from these results that the scattered radiation level at a point correlated with the air Kerma-area product reading irrespective of tube potential, field size or focus skin distance. (orig.)

1995-01-01

44

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1998-03-01

45

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)

2008-01-01

46

Survivor dosimetry. Part B. DS02 free-in-air neutron and gamma tissue kerma relative to DS86  

International Nuclear Information System (INIS)

The major determinant of the radiation dose to a survivor at a given location with respect to the hypocenter of a bomb detonation is the radiation field in the open at that location. Therefore, a change in free-in-air (FIA) kerma at any given distance from the bomb has a proportional effect on the doses of all survivors at that distance, if the shielding is not changed. The fluence-to-kerma coefficients used in the DS02 studies are discussed in Chapter 12, Part A, where one can see that the differences between the newer DS02 and older DS86 kerma coefficients for soft tissues of the body are quite small at the neutron and gamma-ray energies that are most important in the radiation dosimetry for the survivors. Thus, the differences in DS02 and DS86 FIA tissue kermas from neutrons and photons are due essentially to differences in the DS02 and DS86 source term and transport calculations discussed in Chapters 2 and 3. (J.P.N.)

47

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)

2006-01-01

48

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

International Nuclear Information System (INIS)

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 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. (authors)

2010-06-01

49

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)

2005-01-01

50

Comparison of the standards for air kerma of the NMIJ and the BIPM for 60Co ? rays  

International Nuclear Information System (INIS)

A first comparison of the standards for air kerma of the National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology (NMIJ/AIST) and of the Bureau International des Poids et Mesures (BIPM) has been carried out in 60Co radiation. It shows that the NMIJ and BIPM standards differ by 0.72 % with a relative standard uncertainty of 2.4 x 10-3. (authors)

2004-01-01

51

Revised correction factor for the UK national primary standard for air kerma for {sup 137}Cs and {sup 60}Co gamma-rays  

Energy Technology Data Exchange (ETDEWEB)

From 1 May 2009 the United Kingdom National Physical Laboratory (NPL) has changed its air kerma standards for Cs-137 and Co-60 {gamma}-rays. Adoption of the new correction factors results in an increase in the NPL air kerma standard by {approx} 1% for both Cs-137 and Co-60 {gamma}-rays. All NPL secondary standard calibrations issued after 1 May 2009 contain the revised correction factor. (authors)

Pearce, J.; Bass, G.; Duane, S.; Nutbrown, R.; Shipley, D. [National Physical Laboratory, Radiation Dosimetry Group, Teddington, Middlesex (United Kingdom)

2009-10-15

52

Uncertainty evaluation of the kerma in the air, related to the active volume in the ionization chamber of concentric cylinders, by Monte Carlo simulation  

International Nuclear Information System (INIS)

To implant the primary standard of the magnitude kerma in the air for X-ray between 10 - 50 keV, the National Metrology Laboratory of Ionizing Radiations (LNMRI) must evaluate all the uncertainties of measurement related with Victtoren chamber. So, it was evaluated the uncertainty of the kerma in the air consequent of the inaccuracy in the active volume of the chamber using the calculation of Monte Carlo as a tool through the Penelope software

2009-11-09

53

The measurement of beta dose and gamma air kerma rates in the Ribble Estuary  

Energy Technology Data Exchange (ETDEWEB)

As a by-product of the fabrication of uranium fuels, BNFL, Springfields are authorised to discharge beta emitting radionuclides, principally {sup 234m}Pa into the Ribble Estuary. The accumulation of {sup 234m}Pa in the estuarine sediments leads to enhanced beta dose rates not seen elsewhere in the UK. The methods used to determine the beta dose rate and calculate organ and effective doses are presented. The variation in beta dose and gamma air kerma rates in a small area were investigated and recommendations are made as to the number of replicates needed to reduce the error to {approx}10% of the mean. An example of the dose to a walker on the intertidal areas of the Ribble Estuary is calculated by the detailed methods. The effective dose was 73 {mu}Sv a{sup -1}, of which 86% was derived from gamma irradiation. Doses to hands contaminated by estuarine sediments are also low (0.004 {mu}Sv h{sup -1}). (Author).

Mudge, S.M.; Bourne, G.S.; Assinder, D.J. [University of Wales, Bangor (United Kingdom). School of Ocean Sciences

1996-12-01

54

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 cm"2, were calculated when the primary beam impart in an angle of 0 deg. The (secondary) photon beams transmitted respectively by 0,5 meter, 1,0 meter, 1,0 meter and 2,0 meter concrete walls, after they scattered by an angle of 90 deg in a cylindric phantom inside the room, were also determined. Generally, 50 millions of histories were computed for each simulation made for the primary beam. For the 90 deg spread, the number of histories was 100 millions. The computational code used on this work was the MCNP4B. The most common clinic accelerators used on radiotheraphic treatments were used on this work CLINAC-4, CLINAC-6, CLINAC-18 and CLINAC-2500. From the spectra analysis obtained in this work, it was possible to dispose the conversion factor for realistic beams found in radiotherapeutic establishment. (author)

2000-01-01

55

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

International Nuclear Information System (INIS)

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

2009-01-01

56

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

Energy Technology Data Exchange (ETDEWEB)

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%.

Oliveira, L.S.R. [Centro Tecnológico do Exército, CTEx (Brazilian Army Technological Center), Av. das Américas n° 28705, 23085-470 Rio de Janeiro (Brazil); Instituto de Radioprotecão e Dosimetria, CNEN/IRD (Institute for Radioprotection and Dosimetry, CNEN/IRD), Av. Salvador Allende s/no, P.O. Box 37750, 22783-127 Barra da Tijuca, Rio de Janeiro (Brazil); Conti, C.C., E-mail: ccconti@ird.gov.br [Instituto de Radioprotecão e Dosimetria, CNEN/IRD (Institute for Radioprotection and Dosimetry, CNEN/IRD), Av. Salvador Allende s/no, P.O. Box 37750, 22783-127 Barra da Tijuca, Rio de Janeiro (Brazil); Amorim, A.S.; Balthar, M.C.V. [Centro Tecnológico do Exército, CTEx (Brazilian Army Technological Center), Av. das Américas n° 28705, 23085-470 Rio de Janeiro (Brazil)

2013-03-21

57

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

International Nuclear Information System (INIS)

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

2002-04-01

58

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

59

The correlation of air kerma-area product with staff dose in fluoroscopy  

Energy Technology Data Exchange (ETDEWEB)

Radiation doses to staff who perform fluoroscopy can be relatively high compared with other occupationally exposed individuals working in diagnostic radiology and may approach a dose limit or constraint if their workload is high. It is therefore important to be able to monitor and predict radiation doses to staff performing fluoroscopy. Scattered radiation distributions in the vicinity of the patient couch were measured for simulations of both overcouch X-ray tube/undercouch image intensifier and undercouch X-ray tube/overcouch image intensifier fluoroscopy for a wide range of tube potentials (50-110 kV). An experimental arrangement realistic of clinical practice was set up. The effect of field size and focus skin distance was also studied. It was discovered from these results that the scattered radiation level at a point correlated with the air Kerma-area product reading irrespective of tube potential, field size or focus skin distance. (orig.) [Deutsch] Strahlenexpositionen von Personen, die Durchleuchtungen ausfuehren, koennen leicht mit beruflichen Strahlenexpositionen anderer Personen verglichen werden, die in roentgendiagnostischen Abteilungen arbeiten. Bei Durchleuchtungen koennen Dosisgrenzwerte oder Dosisschranken erreicht werden, wenn die Beschaeftigung dieses Personenkreises umfangreich ist. Es ist deshalb wichtig, die Dosen zu messen und Strahlendosen fuer Beschaeftigte, die Durchleuchtungen ausfuehren, im voraus abzuschaetzen. Die Verteilung der Streustrahlung in der Umgebung der Patientenlagerung wurden sowohl fuer Obertischanordnung der Roentgenroehre und Untertischposition des Bildverstaerkers, als auch fuer Untertischanordnung der Roentgenroehre und Obertischposition des Bildverstaerkers in einem weiten Roehren-Spannungsbereich (50 bis 110 kV) gemessen. Eine Versuchsanordnung, die der klinischen Anwendung entspricht, wurde gewaehlt. Der Einfluss der Feldgroesse und des Fokus-Hautabstandes wurden ebenfalls untersucht. Es konnte anhand dieser Versuche festgestellt werden, dass der Anteil der Streustrahlung an einem Punkt, der mit der Dosisflaechenprodukt-Anzeige in Beziehung gebracht wurde, unabhaengig von der Roehrenspannung, der Feldgroesse oder dem Fokus-Haut-Abstand war. (orig.)

Faulkner, K. [Regional Medical Centre, Physics Dept., Newcastle General Hospital, Newcastle upon Tyne (United Kingdom); Marshall, N.W. [Regional Medical Centre, Physics Dept., Newcastle General Hospital, Newcastle upon Tyne (United Kingdom)

1995-12-31

60

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)

2008-01-01

 
 
 
 
61

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)

2002-01-01

62

Comparison of the standards air-kerma of the SZMDM Yugoslavia and the BIPM 60Co ? rays  

International Nuclear Information System (INIS)

A comparison of the standards of air kerma of the Savezni Zavod za Mere i Dragocene Metale (SZMDM) and of the Bureau International des Poids et Mesures (BIPM) has been carried out in 60Co radiation. It shows that the SZMDM and BIPM standards differ by 0.79 % with a relative standard uncertainty of 1.8 x 10-3. This result is compatible with the previous comparison of 1991 when the changes in the corrections for the wall effect and for axial non-uniformity of the SZMDM standard are taken into account. (authors)

2002-01-01

63

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)

2008-01-01

64

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)

2009-01-01

65

The performance of the INER improved free-air ionization chamber in the comparison of air kerma calibration coefficients for medium-energy X-rays  

International Nuclear Information System (INIS)

This paper describes modifications to an original design, correction factors and uncertainty evaluations for an improved free-air ionization chamber constructed at the Institute of Nuclear Energy Research (INER, Taiwan). In addition, a comparison of secondary standard air kerma calibration coefficients for 100-250 kV medium-energy X-rays was performed to verify the experimental accuracy and measurement consistency of the improved chamber. The comparison results showed a satisfactory agreement in the measurements which were within the combined expanded uncertainties (k=2)

2005-01-01

66

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

International Nuclear Information System (INIS)

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

1994-03-01

67

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

International Nuclear Information System (INIS)

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

2009-11-09

68

Re-establishment of the air kerma and ambient dose equivalent standards for the BIPM protection-level 60Co beam  

International Nuclear Information System (INIS)

The air kerma and ambient dose equivalent standards for the protection-level 60Co beam have been re-established following the repositioning of the irradiator and modifications to the beam. Details concerning the standards and the new uncertainty budgets are described in this report with their implications for dosimetry comparisons and calibrations. (authors)

2005-01-01

69

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

International Nuclear Information System (INIS)

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%

2008-02-01

70

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

International Nuclear Information System (INIS)

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

2011-11-01

71

Neutron fluence and kerma free in air in a fission beam  

International Nuclear Information System (INIS)

The reactor-neutron-therapy facility of the Munich research reactor provides an intense beam of fission radiation with nearly equal intensities of the neutron and photon component, both having complex spectral structure in the energy region from 0.01 MeV up to 10 MeV. We determined the physical properties of the beam behind a 2.5 cm lead filter (RENT I) and of the unfiltered beam (RENT II) at a separation distance of 545 cm. Total neutron fluence rates (I: 1.31.108 s-1cm-2, II: 2.28.108 s-1cm-2) and the fission neutron fluence rate (I: 1.3% 0.1.10"8 s"-"1cm"-"2, II: 2.3% 0.2.10"8 s"-"1cm"-"2) were measured by means of the Mn-bath technique and threshold activation detectors, respectively. For the determination of the Kerma rates two pairs of neutron sensitive (t) and insensitive (u) chambers were employed. By means of measurements in the beam without and with additional thin filters of polyethylene the wall effects could be determined separately for the neutron and photon radiation components. This procedure offered the possibility to determine the chamber parameters for any mixed radiation field if the neutron sensitivity ksub(t) could be calculated for the involved fields. The kerma rates at 12kW thermal converter power were found to be for RENT I: Ksub(n) = 21.5 cGy/min and Ksub(g) = 6.4 cGy/min and for RENT II: Ksub(n) = 36.4 cGy/min and Ksub(g) = 32 cGy/min

1984-09-17

72

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

73

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)

2010-05-01

74

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)

2008-10-19

75

Attenuation factors in terms of air kerma to ambient dose equivalent and effective dose for diagnostic X rays rooms  

International Nuclear Information System (INIS)

In the present study, the attenuation of the quantities fluence and air kerma free-in-air by various layers of lead was compared with that of the quantities effective dose, E, and ambient dose equivalent, H*(d). This work aims to calculate the attenuation factors from 50 kV, 125 kV and 150 kV of X ray beams used for medical diagnostic, after transmission through barriers of lead. The X ray qualities used were those recommended by the Birch and Marshall for primary diagnostic X rays. Several lead layers were irradiated with a 50 cm x 50 cm field of primary X ray spectra. The transmitted spectra were calculated to obtain the attenuation factors for beams found in radiodiagnostic services. The calculations were done using the MCNPX Monte Carlo code and voxel model MAX. The values obtained were compared with data derived from the literature. In addition, attenuation factors for X ray qualities after penetration of lead layers were studied to get data which might be of interest in shielding of diagnostic rooms. (author)

2009-10-02

76

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

International Nuclear Information System (INIS)

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 192Ir 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 192Ir 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

2013-07-01

77

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

78

NOTE: Characterization of the radiation quality of 60Co therapy units by the fraction of air kerma attributable to scattered photons  

Science.gov (United States)

In this work we present a new parameter for characterizing the emitted photon spectra of 60Co radiotherapy units. It is intended to propose this parameter for the revised DIN standard 6809-1. In the previous DIN regulation, it had been sufficient to state the nature of the radioactive material within the source. However, scatter processes within the radioactive material as well as the source housing and the collimator system influence the shape of the photon spectrum, with a noticeable contribution in the low-energy portion. The fraction of the air kerma for a given distance from the source, position and beam size in air comprising all contributions by scattered photons up to an upper energy limit for the emitted spectrum from 60Co decay, will be proposed as a typical parameter. The new quantity, which is termed the 'fraction of air kerma attributable to scattered photons', PEScatter, has been calculated for E = 1.17 MeV and compared for four different Monte Carlo-simulated spectra of used 60Co devices. Not included in this new formalism is the air kerma contribution by scattered photons in between the two lines of the 60Co spectrum. A simple measurement procedure based on the signal ratio of two Farmer chamber detectors with different wall materials is discussed and its feasibility shown.

Chofor, N.; Looe, H. K.; Kapsch, R. P.; Harder, D.; Willborn, K. C.; Rühmann, A.; Poppe, B.

2007-04-01

79

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

80

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

 
 
 
 
81

A study of the relationship between peak skin dose and cumulative air kerma in interventional neuroradiology and cardiology  

Energy Technology Data Exchange (ETDEWEB)

A study of peak skin doses (PSDs) during neuroradiology and cardiology interventional procedures has been carried out using Gafchromic XR-RV2 film. Use of mosaics made from squares held in cling film has allowed doses to the head to be mapped successfully. The displayed cumulative air kerma (CAK) has been calibrated in terms of cumulative entrance surface dose (CESD) and results indicate that this can provide a reliable indicator of the PSD in neuroradiology. Results linking PSD to CESD for interventional cardiology were variable, but CAK is still considered to provide the best option for use as an indicator of potential radiation-induced effects. A CESD exceeding 3 Gy is considered a suitable action level for triggering follow-up of patients in neuroradiology and cardiology for possible skin effects. Application of dose action levels defined in this way would affect 8% of neurological embolisation procedures and 5% of cardiology ablation and multiple stent procedures at the hospitals where the investigations were carried out. A close relationship was observed between CESD and dose-area product (DAP) for particular types of procedure, and DAPs of 200-300 Gy cm{sup 2} could be used as trigger levels where CAK readings were not available. The DAP value would depend on the mean field size and would need to be determined for each application.

Neil, S; Padgham, C; Martin, C J [Health Physics, Gartnavel Royal Hospital, Glasgow G12 0XH (United Kingdom)

2010-12-01

82

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)

2010-05-28

83

Calibration of a 7.6 cm x 7.6 cm (3 inch x 3 inch) Sodium Iodide Gamma Ray Spectrometer for Air Kerma Rate  

International Nuclear Information System (INIS)

An experimental procedure is described for converting a gamma ray spectral measurement from a 7.6 cm x 7.6 cm (3 inch x 3 inch) sodium iodide (NaI) detector to air kerma rate. The calibration procedure involves measuring the energy deposited in the detector using 10 radioactive sources of known activity covering an energy range from 60 keV to 1836 keV. For each of the 10 sources, gamma ray spectra were measured with the source at different angles to the detector axis. The total energy deposited in the detector for the ten sources was confirmed by Monte Carlo calculations. The spectra measured at different angles were combined to produce a spectrum that would represent a homogeneous semi-infinite source of radiation. The resultant spectrum was then subdivided into 10 energy regions. Based on the known air kerma rates due to the sources, a calibration coefficient was calculated for each of the 10 energy regions. These calibration coefficients could then be used to convert the energy deposited in the 10 regions of an unknown spectrum to air kerma rate. The calibration procedure was confirmed by comparing the results from the detector with those from calibrated collimated beams of 137Cs and 60Co. A comparison of measurements using a calibrated pressurised ionisation chamber with those from a similar NaI spectrometer in Finland provided additional confirmation of the calibration procedure. (author)

2001-01-01

84

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

Science.gov (United States)

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

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

2013-01-01

85

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...

86

Isopleths of surface air concentration and surface air kerma rate due to a radioactive cloud released from a stack (3)  

International Nuclear Information System (INIS)

This report is a revised edition of 'Isopleths of Surface Air Concentration and Surface Air Absorbed Dose Rate due to a Radioactive Cloud Released from a Stack(II) '(JAERI-M 90-206) and based on the revised Nuclear Safety Guidelines reflected the ICRP1990 Recommendation. Characteristics of this report are the use of Air Karma Rate (Gy/h) instead of Air Absorbed Dose Rate (Gy/h), and the record of isopleths of surface air concentration and surface air karma rate on CD-ROM. These recorded data on CD-ROM can be printed out on paper and/or pasted on digital map by personal computer. (author)

2004-01-01

87

Intercomparison of the air kerma and absorbed dose to water therapy calibrations provided by NRPA and CPRH SSDLs  

International Nuclear Information System (INIS)

The primary goal of any calibration laboratory is to routinely provide calibration services of the highest accuracy. To this end, the laboratory should be equipped with measuring standards of the highest metrological quality traceable to the international measuring system, should establish the appropriate calibration conditions and implement good measuring and working practices. In the case of the Secondary Standard Dosimetry Laboratory (SSDL) members of the IAEA/WHO Network of SSDLs, a great deal of the service quality relies on the appropriate laboratory design and implementation of the recommended calibration practices. Different approaches have been used by SSDLs to guarantee the traceability of the reference standard to the international measurement system. These include calibration of their standards at the IAEA Dosimetry Laboratory, direct calibration at a primary standards laboratory or at a national calibration laboratory. The stability of reference and working standards is usually checked by means of radioactive check source measurements. The most comprehensive way that a laboratory could test its overall measurement competence is by taking part in comparisons with other laboratories of the same or higher metrological level. Regular efforts have been done at the regional scale by organizing such intercomparison exercises where the evaluation of the accuracy of secondary standards or the validation of new calibration methods has been the main objectives. Perhaps, the most important contribution to the assessment of SSDLs quality has been the periodical external measurement audit provided by the IAEA during the last years. Mos of these efforts have, however, only been focused on in-air and recently in-water calibration at the 60Co radiation quality. An intercomparison of the therapy calibration services available at the SSDLs of the Norwegian Radiation Protection Authority (NRPA) and of the Center for Radiation Protection and Hygiene (CPHR) was organized in February 2000. The comparison comprised the calibration of a field class ionization chamber in terms of air kerma at low and medium-energy kilo voltage X-ray qualities and 60Co as well as the calibration in terms of absorbed dose to water (at 60Co radiation quality). The intercomparison represents for the CPHR the validation of the newly implemented calibration service at X-ray qualities. The NRPA SSDL has in recent years participated in EUROMET and IAEA dosimetry intercomparisons with satisfactory results. Experiences derived from the present comparison are discussed and summarized in this report. Recommendations to the SSDL members of the IAEA/WHO Network in order to encourage regional cooperation by organizing similar intercomparison exercises as well as the possibility for the IAEA to extend the present audit services, to cover certain X-ray beam qualities, are also commented

2001-07-01

88

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 cm"3 and 30 cm"3 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 cm"3 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 On

2002-11-25

89

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)

2009-10-02

90

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

International Nuclear Information System (INIS)

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

2002-01-01

91

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)

2003-01-01

92

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

Energy Technology Data Exchange (ETDEWEB)

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

Lima, Marco Antonio Frota

2000-03-01

93

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

94

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

International Nuclear Information System (INIS)

Mammography aims to achieve a high image quality associated with a dose in the patient as low as feasible. Values of average glandular dose, DG, can be obtained by means of two dosimetric methods: one based on the measurement of incident air kerma, Ki, 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 (Ki) and average glandular dose (DG) 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 DG determined from Ki and also with the values of Ki and DG 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 Ki values ranged around 7.9% between the methods of action. The result of the values of DG ranged around 14.7% between the two methods of action. It is observed that the estimate of DG by the software is higher than the values measured with the dosimetric phantom. (author)

2009-10-02

95

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

2002-12-01

96

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)

2005-01-01

97

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

98

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

International Nuclear Information System (INIS)

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

2002-11-25

99

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

100

Ionization chambers for measuring air kerma integrated over beam area. Deviations in calibration values using simplified calibration methods  

International Nuclear Information System (INIS)

Calibrations of kerma-area product meters (KAP meters) are often performed using simplified methods. The accuracy thus obtained can be insufficient, especially when the KAP meters are used for optimizing radiological procedures. The deviations between the best available calibration factor (k) and the simplified calibration factor (ks) were measured at different clinical x-ray installations. Depending on the type of x-ray installation and calibration method, the quotient ks/k ranged from 0.83 to 1.19, reflecting the error made in practice using these methods. A simple alternative calibration method based on comparison with a KAP meter calibrated by the best available method is described. Depending on tube potential and the stability of the electrometers, the uncertainty in the calibration factor derived with this method was between 3.8% and 5.6% (at 95% confidence level). (author)

1998-03-01

 
 
 
 
101

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

102

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

International Nuclear Information System (INIS)

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

2005-01-01

103

Index plants for air pollution  

Energy Technology Data Exchange (ETDEWEB)

Air pollution in cities has caused damage to trees and a decline in the number of trees in the cities. It has caused defoliation of the zelkova trees. Plant damage can be used as an indicator of pollution. Damage symptoms vary according to pollutant and season. Sulfur dioxide (0.8 ppm) caused visible damage on half the potted plants during a laboratory experiment. Ozone also caused damage to plants during experiments.

Kobayashi, Y.

1973-02-01

104

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2009-07-01

105

Toronto air quality index health links analysis  

Energy Technology Data Exchange (ETDEWEB)

Based on data acquired in the year 1995, Toronto Public Health published a report called Air Pollution Burden of Illness in Toronto. In that report, it was estimated that up to 1000 Toronto residents die prematurely each year while another 5500 are admitted to hospitals due to six smog-related air pollutants. In the present document, the authors examined the air quality classifications of the Ontario Air Quality Index (AQI) in an attempt to determine whether the values adequately reflect the state of air quality and the associated burden of illness in Toronto. After careful examination of the results, it became apparent that 92 per cent of the premature mortality and hospitalization took place at times when the Air Quality Index was in the very good or good range. At times when the Air Quality Index was in the moderate or poor-very poor range, an estimated 8 per cent of the burden of illness occurred. These results indicate that the concentration range of a pollutant used to classify the good and very good categories is not always in agreement with the pollutant levels responsible for the adverse health effects. As demonstrated by this study, the air quality associated with the very good or good range described by the AQI is responsible for negative health effects in Toronto, and are lower than the provincial criteria of Ontario. The air quality conditions that may have an impact on health are not always correctly identified by the current AQI system. The authors are recommending a review of the provincial criteria for several air pollutants, and the current AQI system needs to be modified. 16 refs., tabs., figs.

Pengelly, D. [McMaster Inst. of Environment and Health, Hamilton, ON (Canada); Campbell, M.; Macfarlane, R.; Li-Muller, A. [Toronto Public Health, ON (Canada)

2001-10-01

106

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

Directory of Open Access Journals (Sweden)

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

Renata Matos da Luz

2010-02-01

107

Comparison of air kerma standards of LNE-LNHB and NPL for 192Ir HDR brachytherapy sources: EUROMET project no 814  

International Nuclear Information System (INIS)

An indirect comparison has been made in the air kerma standards for high dose rate (HDR) 192Ir brachytherapy sources at the Laboratoire National Henri Becquerel (LNHB) and the National Physical Laboratory (NPL). The measurements were carried out at both laboratories between November and December 2004. The comparison was based on measurements using well-type transfer ionization chambers and two different source types, Nucletron microSelectron HDR Classic and version 2. The results show the reported calibration coefficients to agree within 0.47% to 0.63%, which is within the overall standard uncertainty of 0.65% reported by both laboratories at the time of this comparison. Following this comparison, some of the NPL primary standard correction factors were re-evaluated resulting in a change of +0.17% in the overall correction factor. The new factor was implemented in May 2006. Applying the revised chamber factor to the measurements reported in this comparison report will reduce the difference between the two standards by 0.17%. (note)

2008-03-21

108

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

Energy Technology Data Exchange (ETDEWEB)

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 {mu}Gy h{sup -1} was attributable to Springfields discharges alone. The contribution due to {sup 234m}Pa and {sup 234}Th ranged between 20 and 60%. An excess GAKR (GAKR arising from anthropogenic emissions alone) of 0.139-0.150 {mu}Gy {mu}Gy h{sup -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{sup -1}. (author)

Brown, J.E. [Environmental Sciences, Westlakes Scientific Consulting, Westlakes Science and Technology Park, Moor Row, Cumbria CA24 3LN (United Kingdom); Postgraduate Research Institute for Sedimentology, Reading University, PO Box 227, Reading RG6 2AB (United Kingdom); McDonald, P.; Willans, M. [Environmental Sciences, Westlakes Scientific Consulting, Westlakes Science and Technology Park, Moor Row, Cumbria CA24 3LN (United Kingdom); Parker, A.; Rae, J.E. [Postgraduate Research Institute for Sedimentology, Reading University, PO Box 227, Reading RG6 2AB (United Kingdom)

1999-12-01

109

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)

1999-12-01

110

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

Energy Technology Data Exchange (ETDEWEB)

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)

Lee, J.H.; Hwang, W.S. [Institute of Nuclear Energy Research, Longtan, Taiwan (China); Kotler, L.H.; Webb, D.V. [Australian Radiation Protection and Nuclear Safety Agency, Yallambie (Australia); Buermann, L. [Physikalisch Technische Bundesanstalt, Braunschweig (Germany); Burns, D.T. [Bureau International de Poids et Mesures, 92 - Sevres (France); Takeyeddin, M. [Atomic Energy Commission, Damascus (Syrian Arab Republic); Shaha, V.V. [Bhabha Atomic Research Centre, Mumbai (India); Srimanoroth, S. [Department of Medical Sciences, Nonthaburi (Thailand); Meghzifene, A. [International Atomic Energy Agency, Vienna (Austria); Hah, S.H.; Chun, K.J. [Korea Research Institute of Standards and Science, Yusong (Korea, Republic of); Kadni, T.B. [Malaysian Nuclear Agency, Kajang (Malaysia); Takata, N. [National Metrology Institute of Japan, Tsukuba (Japan); Msimang, Z. [National Metrology Institute of South Africa, Pretoria (South Africa)

2008-10-15

111

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)

2008-10-01

112

Comparison of air kerma measurements between the PTB and the IAEA for x-radiation qualities used in general diagnostic radiology and mammography  

Science.gov (United States)

A comparison of the air kerma standards for x-radiation qualities used in general diagnostic radiology and mammography, identified as EURAMET.RI(I)-S10 (EURAMET project #1221), was performed between the PTB and the IAEA. Two spherical and two parallel-plate reference-class ionization chambers of the IAEA and 12 beam qualities standardized in the IEC standard 61267:2005 plus 7 additional standard beam qualities established at both laboratories were selected for the comparison. The calibration coefficients were determined for the transfer chambers at the PTB in September 2012 and before and after this at the IAEA Dosimetry Laboratory. The results show the calibration coefficients of both laboratories to be in good agreement within the standard uncertainty of the comparison of about 0.47%. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by EURAMET, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Csete, István; Büermann, Ludwig; Gomola, Igor; Girzikowsky, Reinhard

2013-01-01

113

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

1996-01-01

114

Effect of Air Outlet Angle on Air Distribution Performance Index  

Directory of Open Access Journals (Sweden)

Full Text Available       In this paper a numerical study of velocity and temperature distribution in air conditioned space have been made. The computational model consists of the non-isothermal 3-D turbulent with (k-? model. The numerical study is made to conduct air distribution in a room air-conditioned space with real interior dimensions (6×4×3m and to analyze the effect of changing angle of grille vanes on the flow pattern, velocity, and temperature distribution in the room under a set of different condition, and under a supply air temperature of 16?C to examine the final result on air distribution performance index (ADPI.The results show a significant effect within the change of supply air angle, the maximum air distribution performance index (ADPI is 52% when air change per hour (ACH is equal to 10 at 16?C inlet temperature with angle ( 15? down, and the minimum value of (ADPI is 20% when ACH is equal to 15 at 16?C inlet temperature and angle ( degree. 

Isbeyeh W. Maid

2013-05-01

115

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

International Nuclear Information System (INIS)

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

2013-04-01

116

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, 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

2010-11-09

117

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  

Directory of Open Access Journals (Sweden)

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 dados 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.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 measurements 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

2012-04-01

118

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 SciELO Brazil | Language: Portuguese Abstract in portuguese 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.

119

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2005-12-15

120

Index to the AEC/ERDA/DOE Air Cleaning Conferences  

International Nuclear Information System (INIS)

A comprehensive index to the papers in the second through sixteenth AEC/ERDA/DOE Nuclear Air Cleaning Conference is discussed. The index will be published in early 1981 and will be designated as Volume 3 of the proceeding of the sixteenth conference. The index has three parts, a straight numeric tabulation, an author index, and a key word in context (KWIC) index

1980-10-23

 
 
 
 
121

Index to the AEC/ERDA/DOE Air Cleaning Conferences  

Energy Technology Data Exchange (ETDEWEB)

A comprehensive index to the papers in the second through sixteenth AEC/ERDA/DOE Nuclear Air Cleaning Conference is discussed. The index will be published in early 1981 and will be designated as Volume 3 of the proceeding of the sixteenth conference. The index has three parts, a straight numeric tabulation, an author index, and a key word in context (KWIC) index. (JGB)

Burchsted, C.A.

1980-01-01

122

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

123

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

Science.gov (United States)

Local Air Quality Conditions Zip Code: State : National Summary Air Quality Index (AQI) - A Guide to Air Quality and Your Health You will need Adobe Reader ... AirNow PDF page to learn more. Publications Air Quality Index - A Guide to Air Quality and Your ...

124

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

125

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

126

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)

2004-07-11

127

Neutron KERMA factors of Human Tissues  

Directory of Open Access Journals (Sweden)

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

Martin-Martin, A.

2007-07-01

128

KERMA received in neck by woman subject to mammography survey  

International Nuclear Information System (INIS)

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

2010-05-01

129

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

130

Seasonal ARIMA for Forecasting Air Pollution Index: A Case Study  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ai...

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

2012-01-01

131

Kerma transmission through various materials for a p(66)Be(49) neutron beam  

International Nuclear Information System (INIS)

Measurements are described for the Kerma fraction transmitted through several materials considered for shielding, collimation or blocking of fast neutrons produced by a 66 MeV proton beam at the Fermilab Neutron Therapy Facility (NTF). The measurements were made in air using an air filled 1 cm3 spherical ionization chamber. Two beam geometries were employed: 'narrow beam' and 'semi-broad beam'. Results of the total kerma fractions transmitted and for the attenuation lengths are presented for polyethylene, polyethylene concrete, Lipowitz low melting alloy, lead, steel and tungsten. (U.K.)

1981-01-01

132

Air-air heat extraction equipment in air conditioning plants: efficiency indexes and tests  

Energy Technology Data Exchange (ETDEWEB)

This CTI (Italian Thermotechnical Committee) norm, UNI CTI 8/198b, governing the measuring principles and methods relative to air-air heat extraction equipment performance testing, was designed to allow comparisons between different equipment makes. Reference is made to terminology and equipment typology as established by the norm, UNI CTI 8/198a.

1991-02-01

133

Neutron kerma coefficient: Reference tissue for tumours  

International Nuclear Information System (INIS)

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

2010-12-01

134

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.)

2010-11-08

135

Air University Library Index to Military Periodicals. Cumulative Issue January-December 1978. Volume 29, Number 4.  

Science.gov (United States)

The Air University Library Index to Military Periodicals is a subject index to significant articles, news items and editorials appearing in 68 English language military and aeronautical periodicals not indexed in readily available commercial indexing serv...

F. B. Rucks

1978-01-01

136

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

2008-01-01

137

Refractometer for Tracking Changes in the Refractive Index of Air Near 780 nm  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A new system, consisting of a double channel Fabry Perot etalon and laser diodes emitting around 780 nm is described and proposed to be used for air refractive index measurements. The principle of this refractometer is based on frequency measurements between optical laser sources. It permits quasi-instantaneous measurement with a resolution better than and uncertainty in the range. Some preliminary results on the stability of this system and the measurements of the refractive index of air wit...

1998-01-01

138

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)

139

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 bot...

Kermani, M.; Naddafi, K.; Shariat, M.; Mesbah, A. S.

2004-01-01

140

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)

2000-09-06

 
 
 
 
141

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

142

Energy absorption coefficients and photon kerma for LiF  

International Nuclear Information System (INIS)

Accurate knowledge of energy absorption coefficients is needed to calculate the absorbed dose in any material. The photon kerma for LiF relative to air and soft tissue is computed using energy absorption coefficient values for Li, F, air, and tissue. Values of energy absorption coefficients for air are already available in J. H. Hubbell's (Photon Cross-Sections, Attenuation Coefficients and Energy Absorption Coefficients from 10 KeV to 100 GeV. National Standard Reference Data System-National Bureau of Standards Report No. 29, Washington, D. C., 1969) tables. Those for tissue are obtained by adding the weighted average of the energy absorption coefficients to the different elements constituting the tissue. For fluorine, they are computed from the values given by F. H. Attix and W. C. Roesche (Eds, Radiation Dosimetry, Vol. I, Fundamentals. Academic Press, New York/London, 1968) for CaF2 and Ca. The values for lithium have been computed taking into consideration the photoelectric effect, Compton process, and pair production. Corrections for radiative energy losses, fluorescence yields, screening of electrons, etc., are appropriately applied. The energy absorption coefficients due to photoeffect, Compton scattering, and pair production are added to get the total. The energy absorption cross-section data for photon energies from 0.01 to 10 MeV are tabulated for each interaction

1982-01-01

143

Energy absorption coefficients and photon kerma for LiF  

Energy Technology Data Exchange (ETDEWEB)

Accurate knowledge of energy absorption coefficients is needed to calculate the absorbed dose in any material. The photon kerma for LiF relative to air and soft tissue is computed using energy absorption coefficient values for Li, F, air, and tissue. Values of energy absorption coefficients for air are already available in J. H. Hubbell's (Photon Cross-Sections, Attenuation Coefficients and Energy Absorption Coefficients from 10 KeV to 100 GeV. National Standard Reference Data System-National Bureau of Standards Report No. 29, Washington, D. C., 1969) tables. Those for tissue are obtained by adding the weighted average of the energy absorption coefficients to the different elements constituting the tissue. For fluorine, they are computed from the values given by F. H. Attix and W. C. Roesche (Eds, Radiation Dosimetry, Vol. I, Fundamentals. Academic Press, New York/London, 1968) for CaF/sub 2/ and Ca. The values for lithium have been computed taking into consideration the photoelectric effect, Compton process, and pair production. Corrections for radiative energy losses, fluorescence yields, screening of electrons, etc., are appropriately applied. The energy absorption coefficients due to photoeffect, Compton scattering, and pair production are added to get the total. The energy absorption cross-section data for photon energies from 0.01 to 10 MeV are tabulated for each interaction.

Sharada, K.S.

1982-01-01

144

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)

2007-04-18

145

Refractometer for Tracking Changes in the Refractive Index of Air Near 780 nm  

CERN Document Server

A new system, consisting of a double channel Fabry Perot etalon and laser diodes emitting around 780 nm is described and proposed to be used for air refractive index measurements. The principle of this refractometer is based on frequency measurements between optical laser sources. It permits quasi-instantaneous measurement with a resolution better than and uncertainty in the range. Some preliminary results on the stability of this system and the measurements of the refractive index of air with this apparatus are presented. The first measurements of the index of air at 780 nm are, within an experimental uncertainty of the order of, in agreement with the predicted values by the so-called revised Edl\\'en equations. This result is to the best of our knowledge the first to extend to the near infra-red the validity of the revised Edl\\'en equation derived for the wavelength range 350- 650 nm.

Khélifa, N E; Xu, J; Juncar, P; Himbert, M

1998-01-01

146

Suppression of Air Refractive Index Variations in High-Resolution Interferometry  

Directory of Open Access Journals (Sweden)

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

Zden?k Buchta

2011-08-01

147

Estimation of Air Temperature Using Temperature-Vegetation Index (TVX Method  

Directory of Open Access Journals (Sweden)

Full Text Available The determination of air temperature is important in the energy balance calculation, hydrology and meteorological studies. In this regard, the limited number of meteorological stations is one of the serious problems for air temperature determination on a large spatial scale. The remote sensing technique by covering large areas and using updated satellite images might be appropriate for estimation of this parameter. In this research, the negative correlation between land surface temperature and vegetation index (NDVI has been used for air temperature estimation through TVX method in which the inference of air temperature is based on the hypothesis that the temperature of the dense vegetation canopy is close to air temperature. For investigation the performance of TVX method, images of MODIS sensor have been applied for the Sefidrod River basin in the years 1381- 1382-1384. The spilt window technique which was developed by Price has been used for land surface temperature calculation. The mean difference between observed and estimated land surface temperature using Price algorithm was about 6.2Co. This error can affect the air temperature values. Because of using NDVI index in TVX method, this method has the sensitivity to the vegetation density, though in the parts with sparse vegetation, the value of error increases. 4 percent variation of air temperature against the 0.05 increasing of maximum NDVI indicates the high performance of TVX method for air temperature estimation in large areas.

L. Parviz

2011-07-01

148

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

International Nuclear Information System (INIS)

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

1981-01-01

149

Kerma-factor determination by charged-particle spectroscopy  

Energy Technology Data Exchange (ETDEWEB)

Neutron kerma factors can determined by measuring the cross sections, angular distributions and charged-particle emission spectra from (n,z) reactions where z stands for the light charged particles, namely protons, deuterons, tritons, {sup 3}He, or {alpha}-particles, and combining these data with information on the heavy nuclear recoils. This approach is compared with other approaches of determining kerma factors. Data are given near 14 MeV for materials from carbon to niobium.

Haight, R.C.

1994-07-01

150

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 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)

2006-11-13

151

CAQI Common Air Quality Index - Update with PM2.5 and sensitivity analysis.  

Science.gov (United States)

The CAQI or Common Air Quality Index was proposed to facilitate the comparison of air quality in European cities in real-time. There are many air quality indices in use in the world. All are somewhat different in concept and presentation and comparing air quality presentations of cities on the internet was virtually impossible. The CAQI and the accompanying website www.airqualitynow.eu and app were proposed to overcome this problem in Europe. This paper describes the logic of making an index, in particular the CAQI and its update with a grid for PM2.5. To assure a smooth transition to the new calculation scheme we studied the behaviour of the index before and after the changes. We used 2006 Airbase data from 31 urban background and 27 street stations all across Europe (that were monitoring PM2.5 in 2006). The CAQI characterises a city by a roadside and urban background situation. It also insists on a minimum number of pollutants to be included in the calculation. Both were deemed necessary to improve the basis for comparing one city to another. A sensitivity analysis demonstrates the comparative behaviour of the street and urban background stations and presents the sensitivity of the CAQI outcome to the pollutants included in its calculation. PMID:24238948

van den Elshout, Sef; Léger, Karine; Heich, Hermann

2014-08-01

152

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

2004-03-01

153

Trends of air pollution in Denmark - Normalised by a simple weather index model  

Energy Technology Data Exchange (ETDEWEB)

This report is a part of the Traffic Pool projects on 'Traffic and Environments', 1995-99, financed by the Danish Ministry of Transport. The Traffic Pool projects included five different projects on 'Surveillance of the Air Quality', 'Atmospheric Modelling', 'Atmospheric Chemistry Modelling', 'Smog and ozone' and 'Greenhouse effects and Climate', [Rasmussen, 2000]. This work is a part of the project on 'Surveillance of the Air Quality' with the main objectives to make trend analysis of levels of air pollution from traffic in Denmark. Other participants were from the Road Directory mainly focusing on measurement of traffic and trend analysis of the air quality utilising a nordic model for the air pollution in street canyons called BLB (Beregningsmodel for Luftkvalitet i Byluftgader) [Vejdirektoratet 2000], National Environmental Research Institute (HERI) mainly focusing on. measurements of air pollution and trend analysis with the Operational Street Pollution Model (OSPM) [DMU 2000], and the Copenhagen Environmental Protection Agency mainly focusing on measurements. In this study a more simple statistical model has been developed for trend analysis of the air quality. The model is filtering out the influence of the variations from year to year in the meteorological conditions on the air pollution levels. The weather factors found most important are wind speed, wind direction and mixing height. Measurements of CO, NO and NO{sub 2} from three streets in Copenhagen have been used, these streets are Jagtvej, Bredgade and H. C. Andersen's Boulevard (HCAB). The years 1994-1996 were used for evaluation of the method and annual indexes of air pollution index dependent only on meteorological parameters, called WEATHIX, were calculated for the years 1990-1997 and used for normalisation of the observed air pollution trends. Meteorological data were taken from either the background stations at the H.C. Oersted - building situated close to one of the street stations or the synoptic station at Kastrup Airport just outside Copenhagen. The mixing height was calculated using a bulk Richardson method on vertical profiles provided by the Numerical Weather Prediction model DMI-HIRLAM (Danish Meteorological Institute - High Resolution Limited Area Model). The model in general gives a good explanation of variations from year to year in the air quality. (au)

Kiilsholm, S.; Rasmussen, A.

2000-07-01

154

Trends of air pollution in Denmark - Normalised by a simple weather index model  

International Nuclear Information System (INIS)

This report is a part of the Traffic Pool projects on 'Traffic and Environments', 1995-99, financed by the Danish Ministry of Transport. The Traffic Pool projects included five different projects on 'Surveillance of the Air Quality', 'Atmospheric Modelling', 'Atmospheric Chemistry Modelling', 'Smog and ozone' and 'Greenhouse effects and Climate', [Rasmussen, 2000]. This work is a part of the project on 'Surveillance of the Air Quality' with the main objectives to make trend analysis of levels of air pollution from traffic in Denmark. Other participants were from the Road Directory mainly focusing on measurement of traffic and trend analysis of the air quality utilising a nordic model for the air pollution in street canyons called BLB (Beregningsmodel for Luftkvalitet i Byluftgader) [Vejdirektoratet 2000], National Environmental Research Institute (HERI) mainly focusing on. measurements of air pollution and trend analysis with the Operational Street Pollution Model (OSPM) [DMU 2000], and the Copenhagen Environmental Protection Agency mainly focusing on measurements. In this study a more simple statistical model has been developed for trend analysis of the air quality. The model is filtering out the influence of the variations from year to year in the meteorological conditions on the air pollution levels. The weather factors found most important are wind speed, wind direction and mixing height. Measurements of CO, NO and NO2 from three streets in Copenhagen have been used, these streets are Jagtvej, Bredgade and H. C. Andersen's Boulevard (HCAB). The years 1994-1996 were used for evaluation of the method and annual indexes of air pollution index dependent only on meteorological parameters, called WEATHIX, were calculated for the years 1990-1997 and used for normalisation of the observed air pollution trends. Meteorological data were taken from either the background stations at the H.C. Oersted - building situated close to one of the street stations or the synoptic station at Kastrup Airport just outside Copenhagen. The mixing height was calculated using a bulk Richardson method on vertical profiles provided by the Numerical Weather Prediction model DMI-HIRLAM (Danish Meteorological Institute - High Resolution Limited Area Model). The model in general gives a good explanation of variations from year to year in the air quality. (au)

2000-01-01

155

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

156

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

157

A proper method of kerma-length product measurement during QC procedures in panoramic radiography  

International Nuclear Information System (INIS)

As a relevant dose descriptor in panoramic radiography, product of kerma and length PKL is used. The introduction of PKL was recommended by NRPB. Anyway, NRPB termed this quantity dose-width product (DWP), the name product of kerma and length comes from a new dosimetry formalism being developed by IAEA and ICRU. The product of kerma and length in panoramic radiography is an integral of kerma profile created at a front side of the secondary collimator along a line perpendicular to the collimator. The PKL should be measured at a place of maximum intensity of the beam with respect to vertical direction. The signal is integrated over the whole exposure cycle as well. Currently, no dose descriptor in panoramic radiography is measured in the Czech Republic during the QC measurements. Therefore the measurement of PKL should be included in QC procedures as well. A pilot study using three different methods of PKL measurement is being done in the Czech Republic since 2005. The measurements are performed by an X ray film attached to the front side of a secondary collimator, by a column of thermoluminescent detectors (TLDs) and pencil ionization chamber placed perpendicular to the secondary collimator. The results obtained through the mentioned methods agree within 10% generally. The film based method has a significant disadvantage. Air kerma in a profile maximum reaches values up to 30 mGy. Standard X ray films have no dosimetric properties for such a high dose, because the response lies in a region of plateau at a characteristic curve of the film. Therefore, a primary collimator has to be covered by a shielding material. It increases energy dependence of the detection system naturally. An advantage of the film based method is knowledge of a complete kerma distribution within an X ray field. This information is used for proper positioning of a CT pencil ionization chamber or a stack of TLDs within an X ray beam. In the study, monochromatic films Foma Medix XBU (18x24 cm) and a attenuating filter with thickness of 1 mm Cu were used. For film scanning, a laser scanner Lumisys LS50 was used, with scanning resolution 0,2 mm. Before each measurement, the scanner was calibrated by a PTW calibration film in a range of optical densities 0.08/3.4. The simplest and the fastest method is the pencil ionization chamber method. Pencil ionization chambers designed for CT dosimetry were used in the study, especially a type 10X5-3CT with an electrometer Radcal 9015 and a type CT 77336 with an electrometer PTW Nomex 7723. Dependent on a way of calibration of a relevant chamber and an electrometer, a quantity indicated by the electrometer is either integral of kerma profile along a chamber length (Nomex system), which is the required PKL, or just air kerma (Radcal system). In the latter case, indicated air kerma is multiplied by a chamber effective length. Calibration factor of the chambers was verified for beam qualities relevant to panoramic radiography, which are different from those in CT. For a beam quality 50 kV, total filtration 1 mm Al and effective energy Eef 22,7 keV, there was only a 5% difference in calibration factor according to CT energy range. For the TLD measurements, a column of 30 sintered pellets of LiF:Mg, Ti was used. Total length of the TLD column is 27 mm, which is a sufficient length to cover a useful part of the kerma profile. A manual TLD reader Harshaw 4500 was used for the readout of detectors. For routine measurements of several exposure settings at a given X ray unit, TLDs are not appropriate because of time consuming preparation and readout of the dosemeters. The TLD and X ray film systems were calibrated using a reference X ray machine Planmeca Intra in a national reference laboratory for X ray dosimetry. Beam quality for calibration was 70 kV, total filtration 2,2 mm Al, Eef 31 keV. It seems to be most user-friendly and appropriate to measure PKL by means of pencil ionization chamber, for which the calibration factor will be verified for beam qualities relevant to panoramic radiography. A radiogr aphic film should be

2006-11-13

158

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

2006-08-01

159

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

160

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

Directory of Open Access Journals (Sweden)

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

Hanif SedighNejad

2014-01-01

 
 
 
 
161

Displacement Kerma Cross Sections for Neutron Interactions in Molybdenum  

Energy Technology Data Exchange (ETDEWEB)

Modifications to the displacement kerma cross section methods employed in the NJOY99 nuclear data processing code are described. Calculations were performed with the modified code for molybdenum using ENDF-6 neutron interaction data. Results are presented for a range of plausible Ed values.

A. M. Ougouag; C. A. Wemple; C. D. Van Siclen

2004-04-01

162

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

163

The Aggregate Risk Index: An intuitive tool providing the health risks of air pollution to health care community and public  

Science.gov (United States)

In the framework of the European project PASODOBLE (FP7), we set up downstream information services by combining environmental and health data with a view to support the health care community and to improve vulnerable people welfare. Indeed there is a profound relationship between human health, well-being and air pollution levels. The main objectives are to establish correlations between air quality, exposure of populations and their reactivity, to develop and validate air quality indexes and to construct a prediction model of this sanitary index. This index will be implemented on 3 European sites: Greece (Athens and Thessaloniki), the Netherlands and "Provence Alpes Côte d'Azur" (South East of France). The selected region and cities are among the most affected by the atmospheric pollution in Europe and leads to serious sanitary concerns. The service aims to provide up-to-date, detailed information on air quality discomfort. The Aggregate Risk Index is based on the Cairncross's concept, obtained from the Relative Risk associated with short-term exposure to common air pollutants and takes into account the possible effects of a mixture of pollutants. This communication tool, easy to use and intuitive, about the levels of air pollution and the associated health risks, will be used to communicate information to the general population, authorities and to the health care community and will provide advanced warning of potentially health-damaging air pollution events.

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

2012-01-01

164

Calibration of Kerma Area Product Meters with a Patient Dose Calibrator  

International Nuclear Information System (INIS)

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

2011-11-01

165

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

Science.gov (United States)

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 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.

Ioannidou, A.; Papastefanou, C.

2010-01-01

166

The ambient air quality accounts for the Nova Scotia Genuine Progress Index  

International Nuclear Information System (INIS)

The Nova Scotia Genuine Progress Index (GPI) is a measure of sustainable development which provides a complete and accurate picture of our well-being as a society. The GPI assigns explicit values to environmental quality, population health, livelihood security, equity, free time, and educational attainment. The Nova Scotia GPI includes 22 social, economic and environmental components, including ambient air quality. This report investigates Nova Scotia's ambient air concentrations and emissions of carbon monoxide (CO), total particulate matter (PM), sulphur dioxide (SO2), nitrogen oxides (NOx), and volatile organic compounds (VOC). The costs of damages caused by the these key air pollutants are also examined. Exposure to these pollutants results in negative impacts on human health, damage to materials, agricultural crops and changes in forest productivity. From 1979 to 1996, national ambient concentrations of each of these pollutants decreased significantly. However, the national average concentration of ground-level ozone increased by 34 per cent during the same time period. In Nova Scotia, concentrations of CO, PM and SO2 have declined dramatically since 1979, but the trends for NO2 and ground-level ozone do not show significant declines. On a per capita basis, SOx emissions from electric power generation in the province are more than 8 times the Canadian average. The province also had higher per capita emissions of CO, PM, SOx and VOCs than all reporting OECD countries. Electric power generation is the greatest source of fuel combustion emissions in the province, followed by industrial and transportation sources. This report also described some individual actions that can be taken to reduce air pollutant emissions. 174 refs., 37 tabs., 60 figs

2004-01-01

167

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

Energy Technology Data Exchange (ETDEWEB)

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

Costa, Nathalia Almeida

2013-07-01

168

[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

169

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)

2011-11-01

170

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

Science.gov (United States)

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

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

2014-01-01

171

Studies on the local evaluation of the effects of air pollution by biological index, interim report I. On the evaluation of air pollution by remote sensing  

Energy Technology Data Exchange (ETDEWEB)

The amount of arboreal activity locally affected by air pollution and numerical data obtained by transformation of aerial photography of local arboreal activity were compared to determine a biological air pollution index. The remote sensing technique used in Japan is described. The investigation was carried out in Sept. 1973 and Oct. 1972 in 16 districts of Kanagawa prefecture on three evergreen trees and three deciduous trees easily affected by air pollution. A noticeable correlation occurred between arboreal activity of zelkova, ginkgo, castanopsis, and mixed flora and the photographic density and their ratios.

1973-12-01

172

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.

2013-06-17

173

Calibration of kerma-area product meters with a patient dose calibrator  

International Nuclear Information System (INIS)

Full text: Kerma-area product (KAP) meters are used for monitoring patient exposure during x-ray imaging. These field meters are used attached to clinical x-ray system and their calibration should be performed in the same position. Internationally uncertainty < 7% (confidence level 95%) is recommended for KAP measurements. The use of a proper calibration method is important to achieve appropriate measurement accuracy and comparable results. IAEA introduces three options for calibrations of field KAP meters: (1) calibration of the field KAP meter in laboratory (2) field calibration with a air kerma meter as a reference meter (3) field calibration with a KAP meter as a reference meter. In this study the use of novel large patient dose calibrator (PDC) meter as a reference KAP meter is studied. Comparison to the other calibration methods and to use of a conventional type of KAP meter as a reference instrument is made. The use of reference KAP meter was introduced by Toroi et al. as a tandem calibration method. The main drawback to the method is the uncertainty produced by pronounced energy dependence of the response of conventional type of KAP meters. PDC meter type has studied to have lower energy dependence and decreased uncertainty in tandem method is expected when using this type of KAP meter as a reference instrument. Calibrations of reference meters are made at the secondary standard laboratory of STUK with IEC standard radiation qualities. They are recommended and widely used for calibrations of dosimeters in x-ray imaging. As these radiation qualities do not cover the whole range of clinically used radiation qualities, interpolations, and in some cases also extrapolations, of calibration coefficient is needed. In this study the effect of interpolation from standard to clinical radiation qualities on measurement uncertainty is under specific interest. The calibration of PDC meter in SSDL laboratory is also performed with different field sizes and positions. Uniformity of the response is studied and the effects on field calibrations and uncertainties are valuated. Calibrated reference meters are used for calibrations of field KAP meters in clinical x-ray equipments. Special attention will be made on the achieved accuracy. One of the advantage of the tandem calibration method is that the reference KAP value is measured in the same way as the field KAP meter is measuring it (as a surface integral of air kerma). If the reference value is based on air kerma measured in the centre of the x-ray field, the method itself may have some field size dependence. The field size dependence of the methods was studied by Toroi et al. but the comparison was limited by the small size of reference KAP meter. In this study the field size dependence study was extended to larger field sizes. As a conclusion specific uncertainty budget is given for the field KAP meter calibration made with a PDC meter as a reference meter

2010-11-09

174

Response surface models for CFD predictions of air diffusion performance index in a displacement ventilated office  

Energy Technology Data Exchange (ETDEWEB)

Based on the Response Surface Methodology (RSM), the development of first- and second-order models for predicting the Air Diffusion Performance Index (ADPI) in a displacement-ventilated office is presented. By adopting the technique of Computational Fluid Dynamics (CFD), the new ADPI models developed are used to investigate the effect of simultaneous variation of three design variables in a displacement ventilation case, i.e. location of the displacement diffuser (L{sub dd}), supply temperature (T) and exhaust position (L{sub ex}) on the comfort parameter ADPI. The RSM analyses are carried out with the aid of a statistical software package MINITAB. In the current study, the separate effect of individual design variable as well as the second-order interactions between these variables, are investigated. Based on the variance analyses of both the first- and second-order RSM models, the most influential design variable is the supply temperature. In addition, it is found that the interactions of supply temperature with other design variables are insignificant, as deduced from the second-order RSM model. The optimised ADPI value is subsequently obtained from the model equations. (author)

Ng, K.C. [Department of Research and Applications, O.Y.L. R and D Center, Lot 4739, Jalan BRP 8/2, Taman Bukit Rahman Putra, 47000, Sungai Buloh, Selangor Darul Ehsan (Malaysia); Kadirgama, K. [Department of Mechanical Engineering, Universiti Tenaga Nasional, Km. 7, Jalan Kajang-Puchong, 43009 Kajang, Selangor Darul Ehsan (Malaysia); Ng, E.Y.K. [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore)

2008-07-01

175

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

International Nuclear Information System (INIS)

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

2005-01-01

176

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

International Nuclear Information System (INIS)

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

2011-11-01

177

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

International Nuclear Information System (INIS)

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

2013-01-01

178

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

International Nuclear Information System (INIS)

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

1989-04-01

179

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

2005-01-01

180

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

 
 
 
 
181

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

182

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

Science.gov (United States)

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

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

2012-01-01

183

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)

1978-01-01

184

Development of the Critical Care Air Transport Nurse Deployability Index (CCATT-DI).  

Science.gov (United States)

Highly trained Critical Care Air Transport Teams (CCATT) extend the capabilities of aeromedical transportation in the care of critically ill or injured patients from the battlefield. The purpose of this instrument development research is to develop a depl...

N. A. Ryan-Wenger

2007-01-01

185

Feed-Forward Artificial Neural Network Model for Air Pollutant Index Prediction in the Southern Region of Peninsular Malaysia  

Directory of Open Access Journals (Sweden)

Full Text Available This paper describes the application of principal component analysis (PCA and artificial neural network (ANN to predict the air pollutant index (API within the seven selected Malaysian air monitoring stations in the southern region of Peninsular Malaysia based on seven years database (2005-2011. Feed-forward ANN was used as a prediction method. The feed-forward ANN analysis demonstrated that the rotated principal component scores (RPCs were the best input parameters to predict API. From the 4 RPCs, only 10 (CO, O3, PM10, NO2, CH4, NmHC, THC, wind direction, humidity and ambient temp out of 12 prediction variables were the most significant parameters to predict API. The results proved that the ANN method can be applied successfully as tools for decision making and problem solving for better atmospheric management.

Azman Azid

2013-12-01

186

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

The development of a dose reader for the measurement of the radiation dose from neutron and ionizing radiation is presented. The dose reader (kerma meter) is using as active element commercial PIN diodes with long base, which can provide a maximal dependence of the lifetime of minority carriers from the absorbed dose. We consider a simple theory of PIN diodes for the role of the kerma meter and discuss the idea for optimization of the calibration procedure. The characteristics of the dosimete...

Kushpil V.; Kushpil S.; Huna Z.

2012-01-01

187

C/O Kerma coefficient ratio for 96 MeV neutrons deduced from microscopic measurements  

International Nuclear Information System (INIS)

Double-differential cross sections for neutron-induced light-ion production at 96 MeV have been measured for a variety of nuclei at The Svedberg Laboratory. Using the measured cross-section data, we deduce the Kerma coefficient from carbon and oxygen for p, d, t, 3He and ? particles. In order to get the total Kerma for C and O, we add GNASH calculation values where experimental data are not available and obtain a Kerma coefficient of 7.85 ± 0.63 fGy m2 for carbon and 7.09 ± 0.57 fGy m2 for oxygen. The C/O Kerma coefficient ratio then becomes 1.11 ± 0.11. In addition we determine the Kerma ratio between ICRU muscle and A-150, again adding calculations with the GNASH code where no experimental data are available, and obtain a value of 0.98 ± 0.05. While the Kerma coefficients for carbon and oxygen do not agree with the prediction in ICRU Report 63, the ratio values are in good agreement with existing predictions.

2010-12-01

188

C/O Kerma coefficient ratio for 96 MeV neutrons deduced from microscopic measurements  

Energy Technology Data Exchange (ETDEWEB)

Double-differential cross sections for neutron-induced light-ion production at 96 MeV have been measured for a variety of nuclei at The Svedberg Laboratory. Using the measured cross-section data, we deduce the Kerma coefficient from carbon and oxygen for p, d, t, {sup 3}He and {alpha} particles. In order to get the total Kerma for C and O, we add GNASH calculation values where experimental data are not available and obtain a Kerma coefficient of 7.85 {+-} 0.63 fGy m{sup 2} for carbon and 7.09 {+-} 0.57 fGy m{sup 2} for oxygen. The C/O Kerma coefficient ratio then becomes 1.11 {+-} 0.11. In addition we determine the Kerma ratio between ICRU muscle and A-150, again adding calculations with the GNASH code where no experimental data are available, and obtain a value of 0.98 {+-} 0.05. While the Kerma coefficients for carbon and oxygen do not agree with the prediction in ICRU Report 63, the ratio values are in good agreement with existing predictions.

Goettsche, M. [Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala (Sweden); Department of physics, University of Hamburg, Hamburg (Germany); Pomp, S., E-mail: Stephan.Pomp@physics.uu.s [Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala (Sweden); Tippawan, U. [Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala (Sweden); Plasma and Beam Physics Research Facility, Chiang Mai University (Thailand); Andersson, P.; Bevilacqua, R.; Blomgren, J.; Gustavsson, C.; Osterlund, M.; Simutkin, V. [Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala (Sweden)

2010-12-15

189

Assessment of productivity loss in air-conditioned buildings using PMV index  

Energy Technology Data Exchange (ETDEWEB)

This theoretical study reports on the assessment of productivity loss in air-conditioned office buildings using the PMV approach and makes use of Wyon's reviews [D.P. Wyon, P.O. Fanger, B.W. Olesen, C.J.K. Pedersen, The mental performance of subjects clothed for comfort at two different air temperatures, Ergonomics 18 (1975) 358-374; D.P. Wyon, Individual microclimate control: required range, probable benefits and current feasibility, in: Proceedings of Indoor Air '96, Institute of Public Health, Tokyo, 1996; D.P. Wyon, Indoor environmental effects on productivity. IAQ 96 Paths to better building environments/Keynote address. Y. Kevin. Atlanta, ASHRAE, pp. 5-15] as the basis to compare and to relate how the productivity loss could be minimised through improved thermal comfort design criteria. The finding shows that task-related performance is significantly correlated with the human perception of thermal environment that in turn is dependent on temperatures. Different combinations of thermal criteria (air velocity, clo, metabolic, etc.) can lead to similar PMV value and the PMV equation is useful to predict productivity loss that is due to the rate of change in thermal conditions. The study also highlights the issues that remain to be resolved in future research. (author)

Kosonen, R. [Halton OY, Kausala (Finland); Tan, F. [CapitaLand Commercial Limited, Singapore (Singapore)

2004-07-01

190

Predicting bioconcentration of chemicals into vegetation from soil or air using the molecular connectivity index  

Energy Technology Data Exchange (ETDEWEB)

Bioconcentration factors (BCFs) are the ratio of chemical concentration found in an exposed organism (in this case a plant) to the concentration in an air or soil exposure medium. The authors examine here the use of molecular connectivity indices (MCIs) as quantitative structure-activity relationships (QSARS) for predicting BCFs for organic chemicals between plants and air or soil. The authors compare the reliability of the octanol-air partition coefficient (K{sub oa}) to the MC based prediction method for predicting plant/air partition coefficients. The authors also compare the reliability of the octanol/water partition coefficient (K{sub ow}) to the MC based prediction method for predicting plant/soil partition coefficients. The results here indicate that, relative to the use of K{sub ow} or K{sub oa} as predictors of BCFs the MC can substantially increase the reliability with which BCFs can be estimated. The authors find that the MC provides a relatively precise and accurate method for predicting the potential biotransfer of a chemical from environmental media into plants. In addition, the MC is much faster and more cost effective than direct measurements.

Dowdy, D.L.; McKone, T.E.; Hsieh, D.P.H. [Univ. of California, Davis, CA (United States)

1995-12-31

191

Cellulose (delta)18O is an index of leaf-to-air vapor pressure difference (VPD) in tropical plants.  

Science.gov (United States)

Cellulose in plants contains oxygen that derives in most cases from precipitation. Because the stable oxygen isotope composition, ?(18)O, of precipitation is associated with environmental conditions, cellulose ?(18)O should be as well. However, plant physiological models using ?(18)O suggest that cellulose ?(18)O is influenced by a complex mix of both climatic and physiological drivers. This influence complicates the interpretation of cellulose ?(18)O values in a paleo-context. Here, we combined empirical data analyses with mechanistic model simulations to i) quantify the impacts that the primary climatic drivers humidity (e(a)) and air temperature (T(air)) have on cellulose ?(18)O values in different tropical ecosystems and ii) determine which environmental signal is dominating cellulose ?(18)O values. Our results revealed that e(a) and T(air) equally influence cellulose ?(18)O values and that distinguishing which of these factors dominates the ?(18)O values of cellulose cannot be accomplished in the absence of additional environmental information. However, the individual impacts of e(a) and T(air) on the ?(18)O values of cellulose can be integrated into a single index of plant-experienced atmospheric vapor demand: the leaf-to-air vapor pressure difference (VPD). We found a robust relationship between VPD and cellulose ?(18)O values in both empirical and modeled data in all ecosystems that we investigated. Our analysis revealed therefore that ?(18)O values in plant cellulose can be used as a proxy for VPD in tropical ecosystems. As VPD is an essential variable that determines the biogeochemical dynamics of ecosystems, our study has applications in ecological-, climate-, or forensic-sciences. PMID:21245322

Kahmen, Ansgar; Sachse, Dirk; Arndt, Stefan K; Tu, Kevin P; Farrington, Heraldo; Vitousek, Peter M; Dawson, Todd E

2011-02-01

192

Predicting plant uptake of organic chemicals from soil or air using octanol/water and octanol/air partition ratios and a molecular connectivity index  

Energy Technology Data Exchange (ETDEWEB)

A bioconcentration ratio (BCR) represents the ratio of the concentration of a chemical found in an exposed biological system, such as a plant or fish, to the concentration in the exposure medium (water, soil, or air). A comparison is made of the precision and accuracy of the molecular connectivity index (MCI) and the octanol/water partition coefficient (K{sub ow}) as predictors of BCRs from the soil matrix into above- or below-ground vegetation tissues. Calculated octanol/air partition coefficient (K{sub oa}) values are compared with calculated K{sub ow} and MCI values as predictors of measured air-to-plant BCRs. Based on a statistical evaluation of explained variance, residual error, and cross-validation, this evaluation reveals that the MCI provides higher precision, greater ease of use, and a more cost-effective method for predicting the potential bioconcentration of a chemical from soil into above-ground vegetation. Statistical analyses of the various methods reveal that both the K{sub ow} and MCI approaches have a similar level of precision for predicting BCRs from soil solution into roots and, among MCI, K{sub oa} and K{sub ow}; K{sub oa} is somewhat more precise and valid than MCI and K{sub ow} for estimating uptake, but all have limited accuracy as bioconcentration predictors. These latter results are derived mainly from the paucity of both reliable K{sub oa} values and measured air-to-plant BCRs and indicate a need for more experimental measurements from which more accurate models may be developed.

Dowdy, D.L. [Univ. of California, Davis, CA (United States). Dept. of Environmental Toxicology; McKone, T.E. [Univ. of California, Berkeley, CA (United States). School of Public Health

1997-12-01

193

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

Science.gov (United States)

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

Un, A.; Sahin, Y.

2011-07-01

194

Status of Obesity in Terms of Body Mass Index among Indian Air Force Personnel  

Directory of Open Access Journals (Sweden)

Full Text Available Introduction: This paper investigates the prevalence of obesity (BMI >30 kg/m2 among five geographical groups of Indian Air Force personnel of different age. Purpose of study: To observe the status of obesity among IAF and see whether there is age-wise and regional difference in obesity among the different geographical groups. Results: Gradual increase in mean BMI is seen as age of the population increases. There is an overall marked increase in BMI level among all the three age groups for all the other four zones. F-ratio test of normal range BMI does show significant difference among the zones. There is a statistically significant difference in normal BMI (18.5–24.9 wt/ht2 among all the age groups (F-ratio=11.561, p < 0.05. BMI correlated positively with age in the 20-25 age groups (r = 0.119, p= 0.000 and 26-30 age groups (r = 0.075, p= 0.009 respectively, but BMI did not show any statistically significant correlation with age in the 31-35 age group. Observations: A marked increase in overweight and pre-obese prevalence is seen both age and region wise in the IAF personnel if the Asian BMI cut off levels are applied

L. Robert Varte

2011-10-01

195

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

1986-01-01

196

Specific kerma equivalent for photons and neutrons up to 20 MeV  

International Nuclear Information System (INIS)

Specific kerma equivalent, specific Kerma and quality factor have been calculated for photons and neutrons in the photon energy range from 0.1 KeV to 20 MeV and the neutron energy range from thermal neutron energies up to 20 MeV. The latest recomendation of the tissue composition, the LET data for charged particles and more recent cross-sections data for photon and neutron reactions induced in tissue have been used. This information can be used to estimate the radiation dose equivalent and for the interpretation of the tissue-equivalent equidosemeter energy responses

1985-01-01

197

Air  

…below the level at which they can do significant harm. Information & advice from us * Air quality * Emissions to air * Air pollution incidents * Ozone depletion * Acid rain * Pollution inventory data * National atmospheric emissions inventory * National Environmental Technology Centre * Local air quality…

198

Air  

…the level at which they can do significant harm. Information & advice from us * Air quality * Emissions to air * Air pollution incidents * Ozone depletion * Acid rain * Pollution inventory data * National atmospheric emissions inventory * National Environmental Technology Centre * Local air quality management…

199

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

200

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

2009-12-01

 
 
 
 
201

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)

1991-01-01

202

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

Science.gov (United States)

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. PMID:24732883

Li, Li; Qian, Jun; Ou, Chun-Quan; Zhou, Ying-Xue; Guo, Cui; Guo, Yuming

2014-07-01

203

Air  

air * Air pollution incidents * Ozone depletion * Acid rain * Pollution inventory data * National atmospheric emissions inventory * National Environmental Technology Centre * Local air quality management * Air Quality Modelling and Assessment Unit.  See links below for additional information. Mitigation… Related Searches: position statements

204

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.

2012-10-01

205

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

Directory of Open Access Journals (Sweden)

Full Text Available The development of a dose reader for the measurement of the radiation dose from neutron and ionizing radiation is presented. The dose reader (kerma meter is using as active element commercial PIN diodes with long base, which can provide a maximal dependence of the lifetime of minority carriers from the absorbed dose. We consider a simple theory of PIN diodes for the role of the kerma meter and discuss the idea for optimization of the calibration procedure. The characteristics of the dosimeter were measured for a few types of commercial diodes. The device can be useful for many practical tasks of control for radiation environments in the environment, nuclear physics and for industrial application.

Kushpil S.

2012-04-01

206

Analysis of the tandem calibration method for kerma area meters vis Monte Carlo simulations  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The IAEA recommends that uncertainties of dosimetric measurements in diagnostic radiology for risk assessment and quality assurance should be less than 7% on the confidence level of 95%. This accuracy is difficult to achieve with kerma area product (KAP) meters currently used in clinics. The reasons range from the high energy dependence of KAP meters to the wide variety of configurations in which KAP meters are used and calibrated. The tandem calibration method introduced by Pöyry, Komppa an...

2011-01-01

207

Air  

…the position statements on the following: * Environmental taxation * Air quality * Reducing the environmental impacts of road and air transport. Key environmental problems * Global warming and predicted effects of climate change * Strategic assessment of potential emissions * Long-term predictions.…

208

The SAFE (SGRQ score, air-flow limitation and exercise tolerance) Index: a new composite score for the stratification of severity in chronic obstructive pulmonary disease  

Science.gov (United States)

Background This study was proposed to develop a composite of outcome measures using forced expiratory volume percentage of predicted, exercise capacity and quality of life scores for assessment of chronic obstructive pulmonary disease (COPD) severity. Materials and methods Eighty?six patients with COPD were enrolled into a prospective, observational study at the respiratory outpatient clinic, National University Hospital Malaysia (Hospital Universiti Kebangsaan Malaysia ? HUKM), Kuala Lumpur. Results Our study found modest correlation between the forced expiratory volume in 1?s (FEV1), 6?min walk distance and the SGRQ scores with mean (SD) values of 0.97 (0.56)?litres/s, 322 (87)?m and 43.7 (23.6)%, respectively. K?Means cluster analysis identified four distinct clusters which reached statistical significance which was refined to develop a new cumulative staging system. The SAFE Index score correlated with the number of exacerbations in 2 years (r?=?0.497, p<0.001). Conclusion We have developed the SGRQ, Air?Flow limitation and Exercise tolerance Index (SAFE Index) for the stratification of severity in COPD. This index incorporates the SGRQ score, the FEV1 % predicted and the 6?min walk distance. The SAFE Index is moderately correlated with the number of disease exacerbations.

Azarisman, Mohd Shah; Fauzi, Mohd Anshar; Faizal, Mohd Perdaus Ahmad; Azami, Zaharim; Roslina, Abdul Manap; Roslan, Harun

2007-01-01

209

Air  

…Environmental taxation * Air quality * Reducing the environmental impacts of road and air transport. Key environmental problems * Global warming and predicted effects of climate change * Strategic assessment of potential emissions * Long-term predictions. Our long-term objective Cleaner air for everyone…

210

Air  

…Environmental taxation * Air quality * Reducing the environmental impacts of road and air transport. Key environmental problems * Global warming and predicted effects of climate change * Strategic assessment of potential emissions * Long-term predictions. Our long-term objective Cleaner air for everyone… Related Searches: position statements

211

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2011-07-01

212

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

International Nuclear Information System (INIS)

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. (author)

2013-01-01

213

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

2009-08-01

214

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

International Nuclear Information System (INIS)

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

1992-01-01

215

QSPR study on the octanol/air partition coefficient of polybrominated diphenyl ethers by using molecular distance-edge vector index  

Science.gov (United States)

Background The quantitative structure property relationship (QSPR) for octanol/air partition coefficient (KOA) of polybrominated diphenyl ethers (PBDEs) was investigated. Molecular distance-edge vector (MDEV) index was used as the structural descriptor of PBDEs. The quantitative relationship between the MDEV index and the lgKOA of PBDEs was modeled by multivariate linear regression (MLR) and artificial neural network (ANN) respectively. Leave one out cross validation and external validation was carried out to assess the predictive ability of the developed models. The investigated 22 PBDEs were randomly split into two groups: Group I, which comprises 16 PBDEs, and Group II, which comprises 6 PBDEs. Results The MLR model and the ANN model for predicting the KOA of PBDEs were established. For the MLR model, the prediction root mean square relative error (RMSRE) of leave one out cross validation and external validation is 2.82 and 2.95, respectively. For the L-ANN model, the prediction RMSRE of leave one out cross validation and external validation is 2.55 and 2.69, respectively. Conclusion The developed MLR and ANN model are practicable and easy-to-use for predicting the KOA of PBDEs. The MDEV index of PBDEs is shown to be quantitatively related to the KOA of PBDEs. MLR and ANN are both practicable for modeling the quantitative relationship between the MDEV index and the KOA of PBDEs. The prediction accuracy of the ANN model is slightly higher than that of the MLR model. The obtained ANN model shoud be a more promising model for studying the octanol/air partition behavior of PBDEs.

2014-01-01

216

Air  

…Strategy in England and Wales. Policy/position statements Click on the links below to view the position statements on the following: * Environmental taxation * Air quality * Reducing the environmental impacts of road and air transport. Key environmental problems * Global warming and predicted effects of…

217

Air  

…Strategy in England and Wales. Policy/position statements Click on the links below to view the position statements on the following: * Environmental taxation * Air quality * Reducing the environmental impacts of road and air transport. Key environmental problems * Global warming and predicted effects of… Related Searches: position statements

218

Air  

…regulating the release of pollutants into air from over 2000 of the larger or more complex industrial processes. Through our powers in pollution control, we also have an important role in working with Local Authorities, the Highways Agency and other organisations to deliver the Government??s Air Quality…

219

Air  

Air Environment Agency??s roles & responsibilities We play a major role by regulating the release of pollutants into air from over 2000 of the larger or more complex industrial processes. Through our powers in pollution control, we also have an important role in working with Local Authorities, the… Related Searches: position statements

220

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

Science.gov (United States)

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 temperature threshold. In fact, melt does not necessarily occur at daily air temperatures higher than 273.15 K. In this paper, to detect the most indicative threshold witnessing melt conditions in the April-June period, we have analyzed air temperature data recorded from 2006 to 2012 by a supraglacial AWS set up at 2631 m a.s.l. on the ablation tongue of the Forni Glacier (Italian Alps), and by a weather station located outside the studied glacier (at Bormio, a village at 1225 m a.s.l.). Moreover we have evaluated the glacier energy budget and the Snow Water Equivalent (SWE) values during this time-frame. Then the snow ablation amount was estimated both from the surface energy balance (from supraglacial AWS data) and from T-index method (from Bormio data, applying the mean tropospheric lapse rate and varying the air temperature threshold) and the results were compared. We found that the mean tropospheric lapse rate permits a good and reliable reconstruction of glacier air temperatures and the major uncertainty in the computation of snow melt is driven by the choice of an appropriate temperature threshold. From our study using a 5.0 K lower threshold value (with respect to the largely applied 273.15 K) permits the most reliable reconstruction of glacier melt.

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

2014-03-01

 
 
 
 
221

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

222

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

International Nuclear Information System (INIS)

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

2006-09-03

223

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

224

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

International Nuclear Information System (INIS)

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

1989-01-01

225

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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.

 

Method...

Azizifar, M.

2012-01-01

226

Air  

…information. Mitigation opportunities * Policy wording * Refined alternatives * Pollution prevention guidance notes  * Cumulative Effects Assessment (CEA) * Emissions trading. See links below for additional information. * Air Quality Modelling and Assessment Unit (AQMAU) AQMAU is the Environment Agency's… Related Searches: position statements

227

Air  

…information. Mitigation opportunities * Policy wording * Refined alternatives * Pollution prevention guidance notes  * Cumulative Effects Assessment (CEA) * Emissions trading. See links below for additional information. * Air Quality Modelling and Assessment Unit (AQMAU) AQMAU is the Environment Agency's…

228

Scattering study at free air ionization chamber diaphragm  

International Nuclear Information System (INIS)

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

2011-01-01

229

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

2008-06-10

230

Neutron kerma factors for H, C, N, O, and tissue in the energy range of 20 to 70 MeV  

Energy Technology Data Exchange (ETDEWEB)

Calculated kerma factors (kerma per unit fluence) in the energy range of 20 to 70 MeV based on nonelastic charged-particle-production cross-section data obtained from the intranuclear-cascade model of nuclear reactions are given for H, C, N, O, and tissue.

Alsmiller, R.G. Jr.; Barish, J.

1976-12-01

231

Air Quality Guide for Ozone  

Science.gov (United States)

... Code: State : National Summary Air Quality Guide for Ozone You may have seen the Air Quality Index ... http://www.airnow.gov Air Quality Guide for Ozone Air Quality Index Protect Your Health Good (0- ...

232

Measurement of neutron kerma factors in C and O: neutron energy range of 20 MeV to 70 MeV  

International Nuclear Information System (INIS)

Kerma factors for oxygen and carbon have been measured in nearly monoenergetic neutron beams of energies between 34 MeV and 66 MeV. The kerma was determined experimentally with low pressure proportional counters (PC) by measuring the absorbed doses to the gases. Recently calculated gas-to-wall absorbed dose conversion factors, rm,g, were used to deduce the doses in the PC wall materials. The kerma in oxygen was obtained from the difference of the kerma determined with ZrO2 and Zr walled PCs, that in carbon was determined with graphite-walled PCs. The neutron fluence were measured with a proton recoil telescope, the spectral fluences with an NE213 scintillation detector by applying pulse shape and time-of-flight techniques. The kerma factors of carbon from the present measurements were compared with values of previous works which were analysed anew using the improved rm,g values. (author)

1994-10-03

233

Air  

…or more complex industrial processes. Through our powers in pollution control, we also have an important role in working with Local Authorities, the Highways Agency and other organisations to deliver the Government??s Air Quality Strategy in England and Wales. Policy/position statements Click on the…

234

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

235

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

Scientific Electronic Library Online (English)

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

Goldberg, Susana; Weiss, Gabriel.

236

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

1983-01-01

237

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

238

A Distributed Air Index Based on Maximum Boundary Rectangle over Grid-Cells for Wireless Non-Flat Spatial Data Broadcast.  

Science.gov (United States)

In the pervasive computing environment using smart devices equipped with various sensors, a wireless data broadcasting system for spatial data items is a natural way to efficiently provide a location dependent information service, regardless of the number of clients. A non-flat wireless broadcast system can support the clients in accessing quickly their preferred data items by disseminating the preferred data items more frequently than regular data on the wireless channel. To efficiently support the processing of spatial window queries in a non-flat wireless data broadcasting system, we propose a distributed air index based on a maximum boundary rectangle (MaxBR) over grid-cells (abbreviated DAIM), which uses MaxBRs for filtering out hot data items on the wireless channel. Unlike the existing index that repeats regular data items in close proximity to hot items at same frequency as hot data items in a broadcast cycle, DAIM makes it possible to repeat only hot data items in a cycle and reduces the length of the broadcast cycle. Consequently, DAIM helps the clients access the desired items quickly, improves the access time, and reduces energy consumption. In addition, a MaxBR helps the clients decide whether they have to access regular data items or not. Simulation studies show the proposed DAIM outperforms existing schemes with respect to the access time and energy consumption. PMID:24940864

Im, Seokjin; Choi, JinTak

2014-01-01

239

A Distributed Air Index Based on Maximum Boundary Rectangle over Grid-Cells for Wireless Non-Flat Spatial Data Broadcast  

Directory of Open Access Journals (Sweden)

Full Text Available In the pervasive computing environment using smart devices equipped with various sensors, a wireless data broadcasting system for spatial data items is a natural way to efficiently provide a location dependent information service, regardless of the number of clients. A non-flat wireless broadcast system can support the clients in accessing quickly their preferred data items by disseminating the preferred data items more frequently than regular data on the wireless channel. To efficiently support the processing of spatial window queries in a non-flat wireless data broadcasting system, we propose a distributed air index based on a maximum boundary rectangle (MaxBR over grid-cells (abbreviated DAIM, which uses MaxBRs for filtering out hot data items on the wireless channel. Unlike the existing index that repeats regular data items in close proximity to hot items at same frequency as hot data items in a broadcast cycle, DAIM makes it possible to repeat only hot data items in a cycle and reduces the length of the broadcast cycle. Consequently, DAIM helps the clients access the desired items quickly, improves the access time, and reduces energy consumption. In addition, a MaxBR helps the clients decide whether they have to access regular data items or not. Simulation studies show the proposed DAIM outperforms existing schemes with respect to the access time and energy consumption.

Seokjin Im

2014-06-01

240

A Hybrid Method to Improve Forecasting Accuracy - An Introduction of a Day of the Week Index for Air Cargo Weight Data  

Directory of Open Access Journals (Sweden)

Full Text Available Air cargo loading weight forecasting is an important factor for managers in the aviation industry because revenue is dependent on the amount of weight loaded. In this paper, we propose a new method to improve forecasting accuracy and confirm them by the numerical example. Focusing that the equation of exponential smoothing method(ESM is equivalent to (1,1 order ARMA model equation, a new method of estimation of smoothing constant in exponential smoothing method is proposed before by us which satisfies minimum variance of forecasting error. Generally, smoothing constant is selected arbitrarily. But in this paper, we utilize above stated theoretical solution. Firstly, we make estimation of ARMA model parameter and then estimate smoothing constants. Thus theoretical solution is derived in a simple way and it may be utilized in various fields. Combining the trend removing method with this method, we aim to improve forecasting accuracy. Furthermore, “a day of the week index” is newly introduced for the daily air cargo weight data and we have obtained good result. The effectiveness of this method should be examined in various cases.

Tatsuhiro Kuroda

2012-11-01

 
 
 
 
241

Neutron scattering cross sections and partial kerma values for oxygen, nitrogen and calcium at 18  

International Nuclear Information System (INIS)

Recent measurements of differential elastic and inelastic neutron scattering from oxygen, nitrogen and calcium at 18 < Esub(n) < 26 MeV are presented and analysed in terms of the optical model. These data, together with earlier measurements of scattering and total cross sections, are used to construct model potentials that may be used to calculate various quantities of interest in neutron dosimetry in an energy region (20-60 MeV) where very few cross section data are available. The heavy-ion-recoil contribution to kerma is obtained directly from the data at each energy. The value of proton inelastic scattering data for validating potential models at high energy is discussed. (author)

1988-03-01

242

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

International Nuclear Information System (INIS)

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

2005-11-02

243

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

2010-05-28

244

AIR QUALITY MONITORING WITH THE LICHEN BIODIVERSITY INDEX (LBI) IN THE DISTRICT OF FAENZA (ITALY) MONITORING DE LA QUALITÉ DE L’AIR AU MOYEN DE L'INDICE DE BIODIVERSITÉ LICHÉNIQUE (IBL) SUR LE TERRITOIRE DE LA COMMUNE DE FAENZA (ITALIE) MONITORAGGIO DELLA QUALITÀ DELL’ARIA MEDIANTE L'INDICE DI BIODIOVERSITÀ LICHENICA (IBL) NEL TERRITORIO DEL COMUNE DI FAENZA (ITALIA)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The Lichen Biodiversity Index (LBI) is a method for monitoring air pollution. This method employs lichens living on lime trees because they are sensitive to NOx and SOx, and it considers the variations in their communities. This study was performed in 16 stations located in the suburbs of Faenza city town and the result shows a more than acceptable air quality although in some stations the air was affected by the polluting effects of the vehicle traffic.L’...

Manuela Cioffi

2009-01-01

245

HUMAN USE INDEX (FUTURE)  

Science.gov (United States)

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

246

HUMAN USE INDEX  

Science.gov (United States)

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

247

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

International Nuclear Information System (INIS)

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

2011-11-01

248

Ozone - Current Air Quality Index  

Science.gov (United States)

... Quality Conditions Zip Code: State : National Summary Forecast Current AQI AQI Loop More Maps Action Day Highest ... About the Highest 5 Today's Forecasts Tomorrow's Forecasts Current AQI Cowtown, AZ 105 Concord, CA 104 Elk ...

249

Paediatric entrance doses from exposure index in computed radiography  

Energy Technology Data Exchange (ETDEWEB)

Over the last two years we have evaluated paediatric patient doses in projection radiography derived from exposure level (EL) in computed radiography (CR) in a large university hospital. Entrance surface air kerma (ESAK) for 3501 paediatric examinations was calculated from the EL, which is a dose index parameter related to the light emitted by the phosphor-stimulable plate, archived in the Digital Imaging and Communications in Medicine (DICOM) header of the images and automatically transferred to a database using custom-built dedicated software. Typical mean thicknesses for several age bands of paediatric patients was estimated to calculate ESAK from the EL values, using results of experimental measurements with phantoms for the typical x-ray beam qualities used in paediatric examinations. Mean/median ESAK values (in {mu}Gy) for the age bands of <1 year, 1-5 years, 6-10 years and 11-15 years have been obtained for chest without a bucky: 51/41, 57/34, 91/54 and 122/109; chest with a bucky (for only the last three age bands): 114/87, 129/105 and 219/170; abdomen: 119/91, 291/225, 756/600 and 1960/1508 and pelvis: 65/48, 455/314, 943/707 and 2261/1595. Sample sizes of clinical images used for the (indirect) measurements were 1724 for chest without a bucky, 799 for chest with a bucky, 337 for abdomen and 641 for pelvis. The methodology we describe could be applicable to other centres using CR as an imaging modality for paediatrics. Presently, this method is the only practical approach to automatically extract parameters contained in the DICOM header, for the calculation of patient dose values for the CR modality.

Vano, E; Martinez, D; Fernandez, J M; Ordiales, J M; Prieto, C; Floriano, A [Medical Physics Service, San Carlos University Hospital, 28040 Madrid (Spain); Ten, J I [Diagnostic Radiology Service, San Carlos University Hospital, 28040 Madrid (Spain)], E-mail: eliseo@med.ucm.es

2008-06-21

250

Paediatric entrance doses from exposure index in computed radiography  

International Nuclear Information System (INIS)

Over the last two years we have evaluated paediatric patient doses in projection radiography derived from exposure level (EL) in computed radiography (CR) in a large university hospital. Entrance surface air kerma (ESAK) for 3501 paediatric examinations was calculated from the EL, which is a dose index parameter related to the light emitted by the phosphor-stimulable plate, archived in the Digital Imaging and Communications in Medicine (DICOM) header of the images and automatically transferred to a database using custom-built dedicated software. Typical mean thicknesses for several age bands of paediatric patients was estimated to calculate ESAK from the EL values, using results of experimental measurements with phantoms for the typical x-ray beam qualities used in paediatric examinations. Mean/median ESAK values (in ?Gy) for the age bands of <1 year, 1-5 years, 6-10 years and 11-15 years have been obtained for chest without a bucky: 51/41, 57/34, 91/54 and 122/109; chest with a bucky (for only the last three age bands): 114/87, 129/105 and 219/170; abdomen: 119/91, 291/225, 756/600 and 1960/1508 and pelvis: 65/48, 455/314, 943/707 and 2261/1595. Sample sizes of clinical images used for the (indirect) measurements were 1724 for chest without a bucky, 799 for chest with a bucky, 337 for abdomen and 641 for pelvis. The methodology we describe could be applicable to other centres using CR as an imaging modality for paediatrics. Presently, this method is the only practical approach to automatically extract parameters contained in the DICOM header, for the calculation of patient dose values for the CR modality

2008-06-21

251

Paediatric entrance doses from exposure index in computed radiography.  

Science.gov (United States)

Over the last two years we have evaluated paediatric patient doses in projection radiography derived from exposure level (EL) in computed radiography (CR) in a large university hospital. Entrance surface air kerma (ESAK) for 3501 paediatric examinations was calculated from the EL, which is a dose index parameter related to the light emitted by the phosphor-stimulable plate, archived in the Digital Imaging and Communications in Medicine (DICOM) header of the images and automatically transferred to a database using custom-built dedicated software. Typical mean thicknesses for several age bands of paediatric patients was estimated to calculate ESAK from the EL values, using results of experimental measurements with phantoms for the typical x-ray beam qualities used in paediatric examinations. Mean/median ESAK values (in microGy) for the age bands of bucky: 51/41, 57/34, 91/54 and 122/109; chest with a bucky (for only the last three age bands): 114/87, 129/105 and 219/170; abdomen: 119/91, 291/225, 756/600 and 1960/1508 and pelvis: 65/48, 455/314, 943/707 and 2261/1595. Sample sizes of clinical images used for the (indirect) measurements were 1724 for chest without a bucky, 799 for chest with a bucky, 337 for abdomen and 641 for pelvis. The methodology we describe could be applicable to other centres using CR as an imaging modality for paediatrics. Presently, this method is the only practical approach to automatically extract parameters contained in the DICOM header, for the calculation of patient dose values for the CR modality. PMID:18523350

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

2008-06-21

252

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

International Nuclear Information System (INIS)

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

1996-01-01

253

Hydrocarbons and Air Pollution: An Annotated Bibliography. Part I., Categories A to E and Part II., Categories F to M and Indexes.  

Science.gov (United States)

This two-part bibliography represents an effort to collect, condense, and organize the literature on the hydrocarbons in relation to air pollution. The approximately 2,300 documents abstracted are all included in the information storage and retrieval system of the National Air Pollution Control Administration's (NAPCA) Air Pollution Technical…

National Air Pollution Control Administration (DHEW), Raleigh, NC.

254

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

255

Measurement of neutron kerma factors in C and O: neutron energy range of 20 MeV to 70 MeV  

Energy Technology Data Exchange (ETDEWEB)

Kerma factors for oxygen and carbon have been measured in nearly monoenergetic neutron beams of energies between 34 MeV and 66 MeV. The kerma was determined experimentally with low pressure proportional counters (PC) by measuring the absorbed doses to the gases. Recently calculated gas-to-wall absorbed dose conversion factors, r{sub m,g}, were used to deduce the doses in the PC wall materials. The kerma in oxygen was obtained from the difference of the kerma determined with ZrO{sub 2} and Zr walled PCs, that in carbon was determined with graphite-walled PCs. The neutron fluence were measured with a proton recoil telescope, the spectral fluences with an NE213 scintillation detector by applying pulse shape and time-of-flight techniques. The kerma factors of carbon from the present measurements were compared with values of previous works which were analysed anew using the improved r{sub m,g} values. (author).

Schrewe, U.J.; Brede, H.J.; Dangendorf, V. [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany)] [and others

1995-12-31

256

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.

2010-06-20

257

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

258

Influence of ion chamber response on in-air profile measurements in megavoltage photon beams  

International Nuclear Information System (INIS)

This article presents an investigation of the influence of the ion chamber response, including buildup caps, on the measurement of in-air off-axis ratio (OAR) profiles in megavoltage photon beams using Monte Carlo simulations with the EGSnrc system. Two new techniques for the calculation of OAR profiles are presented. Results of the Monte Carlo simulations are compared to measurements performed in 6, 10 and 25 MV photon beams produced by an Elekta Precise linac and shown to agree within the experimental and simulation uncertainties. Comparisons with calculated in-air kerma profiles demonstrate that using a plastic mini phantom gives more accurate air-kerma measurements than using high-Z material buildup caps and that the variation of chamber response with distance from the central axis must be taken into account

2005-09-01

259

Energy dependence of kerma of thermoluminescent glass dosemeters for photons with energy till 6 MeV  

International Nuclear Information System (INIS)

Experimentally determined is energy dependence of ICG dosemeters (individual control by means of glasses) in the photon energy range from 1 to 6 MeV. The ICG dosemeters of 4x15x15 mm3 dimensions in standard filters compensating energy dependence in the photon energy range from 0.03 to 1.25 MeV. To irradiate the dosemeters the following photon sources were used: 1.38 and 2.76 MeV 24Na source; Pu-?-? 16N neutron source with 4.45 MeV gamma radiation and 6.13 MeV 16N source. Energy dependence of the dosemeters was determined by the kerma which, in turn, was determined by experimentally measured depth absorption doses in a medium equivalent to a detector. It has been established, that ICG energy dependence within the investigated energy range increases, but not more than by 20 %

1978-01-01

260

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2012-10-01

 
 
 
 
261

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

262

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.

263

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

1991-09-25

264

UK Index  

Science.gov (United States)

The UK Index provides a searchable index of resources in or about the United Kingdom. The Quick Reference section offers links to News Resources in the UK such as the BBC, weather information, UK record charts, and UK related USENET newsgroups. The Foreign & Commonwealth Office provides good advice for travelers. The search engine allows the selection of categories such as arts or business to restrict the search to pages included in one category or a combination of categories.

265

[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

266

Heat Index  

Science.gov (United States)

... Graphical Fire Weather Aviation Weather Air Quality Current Weather Observations Satellite Images Rivers/Lakes Oklahoma Mesonet West Texas Mesonet Radar Imagery Nationwide Central Oklahoma SW OK/NW TX Northern ...

267

Biometeorological comfort index  

Energy Technology Data Exchange (ETDEWEB)

The paper aims to represent and scale biometeorological sensations through a thermal index which comprises the effects of temperature, humidity and wind. The cooling power of a measured combination of wind speed and air temperature is equated with that due to the combination of a reference wind speed (related to the air movement experienced by a person walking in still air), and a derived ''aerodynamic'' temperature. A ''biometeorological'' temperature which is the average of such an ''aerodynamic'' temperature and a conventionally measured wet bulb temperature is shown to afford a better measure of comfort in Spain than some other, alternative indices.

Rodriguez, C.; Mateos, J.; Garmendia, J.

1985-01-01

268

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

1995-01-01

269

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

270

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

International Nuclear Information System (INIS)

The authors present evaluations of the interaction of 20 to 100 MeV neutrons with calcium and phosphorus, which follows on from the previous work on carbon, nitrogen, and oxygen. The aim is to accurately represent integrated cross sections, inclusive emission spectra, and kerma factors, in a data library which can be used in radiation transport calculations. They apply the GNASH nuclear model code, which includes Hauser-Feshbach, preequilibrium, and direct reaction mechanisms, and use experimental measurements to optimize the calculations. Total, elastic, and nonelastic cross sections, angle-energy correlated emission spectra for light ejectiles with A ? 4 and gamma-rays, and average energy depositions, are determined. The expected accuracy of the calculated cross sections and kerma factors is discussed

1995-01-01

271

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

272

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2013-11-15

273

Jung Index  

Science.gov (United States)

Compiled by Matthew Clapp of the University of Georgia, the Jung Index is a collection of more than 300 online resources about and related to the life and work of Carl Jung, the Swiss psychologist and psychiatrist who founded analytic psychology. Resources are indexed into ten major topic areas and include sections such as Research Resources, Jungian Psychology, and Psychoanalysis, among others. A What's New? section, a What's Cool? section, and the JungNet Newsletter keep frequent visitors up to date on the latest and greatest resources in analytic psychology. In addition, the site provides a glossary of Jungian terms, a gallery of Jungian images, and a moderated forum for Jungian discussion.

1999-01-01

274

Entropy | Indexing &  

...covered by following databases and archives: Indexing & Abstracting Services CAS - Chemical Abstracts (ACS) Current Contents - Physical, Chemical & Earth Sciences ( Thomson Reuters) DBLP Computer Science Bibliography (Universität Trier) DOAJ - Directory of Open Access Journals Energy & Power Source (EBSCO) INSPEC (IET) io-port (FIZ Karlsruhe) Journal Citation Report (Thomson Reuters) MathSciNet (American Mathematical Society) SCIE - Science Citation Index Expanded (Thomson Reuters) SciSearch (...Thomson Reuters) Scopus (Elsevier) Web of Science (Thomson Reuters) Zentralblatt MATH (FIZ Karlsruhe) Full-text Archives CLOCKSS (Digital Archive System) e-Helvetica (Swiss National Library Archive) LOCKSS (Lots of Copies Keep Stuff Safe) Content Aggregators EBSCOhost (EBSCO Publishing) J-Gate (Informatics India) Entropy EISSN 1099-4300 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert Terms & Conditions Privacy Policy Contact MDPI Payment Information Jobs at MDPI ...

275

A QUANTITATIVE EVALUATION OF THE POLLUTANT STANDARDS INDEX  

Science.gov (United States)

The U.S. Environmental Protection Agency has recommended a daily air pollution index for use by State and local air pollution control agencies--the Pollutant Standards Index (PSI). The new index makes use of segmented linear functions which convert measured concentrations of each...

276

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 SciELO Argentina | Language: Spanish Abstract in spanish 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.

277

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

278

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

International Nuclear Information System (INIS)

A program is being carried out at Lawrence Livermore National Laboratory to develop high-energy evaluated nuclear data libraries for use in Monte Carlo simulations of cancer radiation therapy. In this report we describe evaluated cross sections and kerma factors for neutrons with incident energies up to 100 MeV on 12C. The aim of this effort is to incorporate advanced nuclear physics modeling methods, with new experimental measurements, to generate cross section libraries needed for an accurate simulation of dose deposition in fast neutron therapy. The evaluated libraries are based mainly on nuclear model calculations, benchmarked to experimental measurements where they exist. We use the GNASH code system, which includes Hauser-Feshbach, preequilibrium, and direct reaction mechanisms. The libraries tabulate elastic and nonelastic cross sections, angle-energy correlated production spectra for light ejectiles with A?and kinetic energies given to light ejectiles and heavy recoil fragments. The major steps involved in this effort are: (1) development and validation of nuclear models for incident energies up to 100 MeV; (2) collation of experimental measurements, including new results from Louvain-la-Nueve and Los Alamos; (3) extension of the Livermore ENDL formats for representing high-energy data; (4) calculation and evaluation of nuclear data; and (5) validation of the libraries. We describe the evaluations in detail, with particular emphasis on our new high-energy modeling developments. Our evaluations agree well with experimental measurements of integrated and differential cross sections. We compare our results with the recent ENDF/B-VI evaluation which extends up to 32 MeV

1995-01-01

279

Determination of the kerma factors in tissue-equivalent plastic, C, Mg, and Fe for 14.7-MeV neutrons  

International Nuclear Information System (INIS)

Microdosimetric measurements were made with tissue-equivalent plastic, (TEP), C-, Mg-, and Fe-, walled proportional counters filled with propane-based TE gas and Ar gas and irradiated with 14.7-MeV neutrons. A theoretical model was used for the analysis of energy deposition in spherical detectors. An effective average mass stopping-power ratio and a W correction were calculated to convert the gas ionization to the kerma in the wall material. The neutron fluence at the position of microdosimetric measurements was determined with an associated particle chamber mounted with surface barrier detectors. The experimental measurements along with the calculated correction factors yielded kerma factors of 0.660 x 10-8 cGy cm2 for TEP, 0.219 x 10-8 cGy cm2 for C, 0.122 x 10-8 cGy cm2 for Mg, and 0.479 x 10-9 cGy cm2 for Fe. The estimated uncertainties are 8.0% for TEP, 10.5% for C, and 9.3% for Mg and Fe

1987-01-01

280

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

 
 
 
 
281

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

1982-01-01

282

Kitap ?ndeksleri / Book Indexing  

Directory of Open Access Journals (Sweden)

Full Text Available This article is a review of Book Indexes from a variety of points, which are in fact the oldest indexes used in the world. They are different than journal indexes and database indexes which are ongoing projects. Book indexes, on the other hand, are unique in their own frameworks, as each one is a completed and finished unit. Construction of book indexes, types of indexes (according to subject headings and proper names, synthesis and analytic methods; and formats of indexes (indented and run-in formats are described. There is a list of important conventions relating to book indexes at the end of the article

Meral Alaku?

2006-04-01

283

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

284

Spatial variability of air dry bulb temperature and black globe humidity index in a broiler house during the heating phase / Variabilidade espacial de variáveis ambientais em um galpão avícola durante a fase de aquecimento  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese A temperatura de bulbo seco do ar (t bs) bem como o índice de temperatura do globo negro e umidade (ITGU) exercem grande influência no desenvolvimento de frangos de corte durante a fase de aquecimento. Sendo assim, o objetivo deste trabalho foi analisar a estrutura e a magnitude da variabilidade esp [...] acial da t bs e ITGU, utilizando ferramentas da geoestatística por meio de análise de semivariograma e, ainda, a produção de mapas de isolinhas por meio de interpolação por krigagem. O experimento foi conduzido na mesorregião oeste de Minas Gerais, na primavera de 2010, em um galpão comercial com sistema de aquecimento constituído de duas fornalhas de aquecimento indireto do ar, durante os primeiros 14 dias de vida das aves. Os dados foram registrados em intervalos de cinco minutos, no período das 8 às 10 horas. As variáveis foram avaliadas por semivariograma ajustado pelo método da máxima verossimilhança restrita (REML), testando-se os modelos esférico e exponencial. Os mapas de krigagem foram produzidos baseados no melhor método de ajuste do semivariograma. As técnicas da geoestatística possibilitaram caracterizar a variabilidade da t bs e ITGU, permitindo a observação da dependência espacial. Além disso, com a utilização da geoestatística e dos mapas de distribuição, pode-se identificar falhas no sistema de aquecimento, em regiões do galpão que poderiam vir a prejudicar o desenvolvimento dos pintinhos. Abstract in english The air dry-bulb temperature (t db),as well as the black globe humidity index (BGHI), exert great influence on the development of broiler chickens during their heating phase. Therefore, the aim of this study was to analyze the structure and the magnitude of the t db and BGHI spatial variability, usi [...] ng geostatistics tools such as semivariogram analysis and also producing kriging maps. The experiment was conducted in the west mesoregion of the states of Minas Gerais in 2010, in a commercial broiler house with heating system consisting of two furnaces that heat the air indirectly, in the firsts 14 days of the birds' life. The data were registered at intervals of five minutes in the period from 8 a.m. to 10 a.m. The variables were evaluated by variograms fitted by residual maximum likelihood (REML) testing the Spherical and Exponential models. Kriging maps were generated based on the best model used to fit the variogram. It was possible to characterize the variability of the t db and BGHI, which allowed observing the spatial dependence by using geostatistics techniques. In addition, the use of geostatistics and distribution maps made possible to identify problems in the heating system in regions inside the broiler house that may harm the development of chicks.

Ponciano, Patrícia F.; Yanagi Junior, Tadayuki; Ferraz, Gabriel A. E S.; Scalon, João D.; Schiassi, Leonardo.

285

UV (Ultraviolet) Index  

Science.gov (United States)

... Environmental Protection Agency Search Search Contact Us SunWise UV Index Check your UV Index Tip: If your ... What factors affect the level of UV radiation? UV Index Forecast The forecast map shows contour lines ...

286

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.

2010-12-01

287

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

288

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)

2010-01-01

289

Journal selection and indexing for Index Medicus and Chinese periodicals indexed in Index Medicus  

Directory of Open Access Journals (Sweden)

Full Text Available Index Medicus / MEDLINE / PubMed published by U.S. National Library of Medicine (NLM is the most important and commonly used biomedical literature retrieval system in the world. According to the "List of Journals Indexed in Index Medicus (2004", 4 098 journals are indexed for Index Medicus, including 70 journals from mainland China and Hong Kong and 9 journals from Taiwan. Journal of Chinese Integrative Medicine established in May, 2003 is indexed in Index Medicus in 2004. This article outlines the critical elements of journal selection for Index Medicus/MEDLINE and the journal selection process for indexing at NLM, and introduces some measures for the Journal of Chinese Integrative Medicine being indexed in Index Medicus / MEDLINE.

ZHOU Qing-Hui

2005-01-01

290

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

2010-04-28

291

Nucleic acid indexing  

Energy Technology Data Exchange (ETDEWEB)

A restriction site indexing method for selectively amplifying any fragment generated by a Class II restriction enzyme includes adaptors specific to fragment ends containing adaptor indexing sequences complementary to fragment indexing sequences near the termini of fragments generated by Class II enzyme cleavage. A method for combinatorial indexing facilitates amplification of restriction fragments whose sequence is not known.

Guilfoyle, Richard A. (Madison, WI); Guo, Zhen (Bellevue, WA)

2001-01-01

292

Nucleic acid indexing  

Energy Technology Data Exchange (ETDEWEB)

A restriction site indexing method for selectively amplifying any fragment generated by a Class II restriction enzyme includes adaptors specific to fragment ends containing adaptor indexing sequences complementary to fragment indexing sequences near the termini of fragments generated by Class II enzyme cleavage. A method for combinatorial indexing facilitates amplification of restriction fragments whose sequence is not known.

Guilfoyle, Richard A. (Madison, WI); Guo, Zhen (Bellevue, WA)

1999-01-01

293

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

2013-12-01

294

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

295

Air pollution in the United Kingdom  

Energy Technology Data Exchange (ETDEWEB)

This book gives a brief but authoritative and up-to-date overview of air pollution in the UK. It describes the major air pollution problems facing the country, illustrated in part with data provided by the national monitoring network. Chapters are entitled: indoor air pollution; urban air pollution in the United Kingdom; rural air pollution in the United Kingdom; global air pollution problems - present and future; the health effects of air pollution in the United Kingdom; current and future legislation - United Kingdom and Europe; developments in air pollution measurement techniques; quality assurance and quality control of ambient air quality; subject index.

Hewett, C.N.; Davison, G. [eds.] [Lancaster University, Lancaster (United Kingdom)

1997-12-31

296

Supersymmetry and index theory  

International Nuclear Information System (INIS)

The author presents information mainly concerned with the fact that many of the ingredients and results in index theory have very simple analogs in supersymmetric quantum mechanical systems so that using elementary quantum mechanics one can obtain new proofs of the Atiyah-Singer index theorem and related results. Simple ideas on index theorems and characteristic classes are reviewed; simple results on fermion functional integrals are outlined; supersymmetric quantum mechanical systems which appear naturally in dealing with index problems are analyzed; proof of the classical index theorem is presented; the character valued index theorem is derived; and applications of the methods developed here for the computation of anomalies are presented

1985-01-01

297

Kaiser's Systematic Indexing.  

Science.gov (United States)

Describes a system of subject indexing developed by Julius Kaiser (1868-1927) which is based on "concretes" and "processes" to govern the form of subject headings and subdivisions. Elements of amplification, guides for the subject index, and criticism of Kaiser's systematic indexing are noted. Five sources are given. (EJS)

Rodriguez, Robert D.

1984-01-01

298

ZZ DLC-14 AIR, Group Constant Library of Secondary Gamma Transport in Air for ANISN Calculation  

International Nuclear Information System (INIS)

1 - Nature of physical problem solved: Format: ANISN, DOT, MORSE (FIDO format); Number of groups: 22 neutron / 18 gamma-ray; Nuclides: air; Origin: ENDF/B for neutron cross sections, DLC-4/HPIC for gamma-ray and DLC-12/POPLIB for secondary gamma-ray production. Weighting spectrum: 1/E for neutron cross sections. The basic idea behind the distribution of this ANISN input data is to allow potential users to repeat the ANISN calculations reported in ref. (1). It is felt that it will be more economical to repeat the calculations rather than to distribute the results of the Straker-Gritzner (1) calculations. However, the cross section part of the data can actually be used in DOT or MORSE or any transport code which will accept input cross section in the FIDO format. 2 - Method of solution: The sample input data for ANISN are for a P5, S16 calculation of the transport of neutrons and secondary gamma-rays from a 12.2 to 15 MeV point neutron source in an infinite air medium. The source is actually uniformly distributed in the first interval (500 cm radius) of a spherical medium of air with radius 3005 meters. The problem is set up for calculating various 'detector responses' by means of the 'activity' option available with ANISN. This is accomplished by providing a cross section table for a 'material' which has detector responses in certain table positions. Then the inclusion of appropriate input data for 22$ and 23$ arrays causes the group fluxes to be multiplied by the group response function values to give the desired answer. The neutron detector responses calculated by this sample problem are Henderson tissue dose, Snyder-Neufeld dose, tissue kerma, and air kerma. The gamma-ray response functions calculated are Henderson tissue dose and air kerma. The neutron cross sections were first reduced from point data from ENDF/B to a 104 fine group structure with a modified version of CSP, assuming a 1/E weighting factor. The gamma-ray data were reduced from point data from DLC-4/HPIC to an 18 group structure using MUG. The POPOP-4 code was used to convert secondary gamma-ray production data from DLC-12/POPLIB to neutron-to-gamma-ray group transfer cross sections. The coupled set (104 neutron, 18 gamma-ray groups) was then collapsed to 22 neutron and 18 gamma-ray groups with ANISN, using as the weighting function the spectrum from a spatially uniform source of 14 MeV neutrons in an infinite air medium with a density of 1.11 mg/cc. The resulting data are coupled macroscopic multigroup, P5 expansion cross sections for air punched on cards and suitable for input to the ANISN code

1972-01-01

299

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)

2013-01-01

300

Stamping Forming Quality Index  

Directory of Open Access Journals (Sweden)

Full Text Available The study proposes that stamping forming quality index should include defect quality index and thickness variation uniformity quality index and different types of stamping parts focus on different defect quality index .Moreover, the fracture and wrinkle quality index can be demonstrated by the distance between the major strain of the simulation unit and the critical curve of the fracture and wrinkle trend in FLD, while thickness variation uniformity quality index can be expressed by variance of sheet metal thinning rate. It takes the automobile back plate reinforcement as the example, select stamping quality index as optimization objectives and constraint conditions based on numerical simulation technology, then apply the technical means that contain with orthogonal test design, neural network and genetic algorithm to optimize the process variables. The result indicates that the method of this study is feasible and effective and has application value in engineering.

Yanping Zheng

2013-01-01

 
 
 
 
301

Measuring the Molecular Polarizability of Air  

CERN Multimedia

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 at atmospheric pressure to be n = 1.0002651(66), which is in agreement with the accepted value of n=1.000271375(6).

Madsen, M J; Krutz, S R; Milliman, M J

2009-01-01

302

Optimization on indoor air diffusion of floor-standing type room air-conditioners  

Energy Technology Data Exchange (ETDEWEB)

The indoor air diffusion of a typical office equipped with a floor-standing type air-conditioner (FSAC) in summer was evaluated and optimized. Two existing evaluation indexes, the air diffusion performance index and the energy utilization coefficient, were modified for their more reasonable application in the evaluation on air diffusion performance of a FSAC. And also, a new index, fast cooling effect index, was presented to evaluate the fast-cooling effect. Based on the indoor airflow simulation using computational fluid dynamics, the three indexes were applied to evaluate the air diffusion performance of the FSAC. As a result, the optimal indoor air diffusion types with best thermal feelings, fine energy utilization efficiency and excellent fast-cooling effect were obtained, and also, a control scheme was suggested. (author)

Weiwei Liu; Zhiwei Lian; Ye Yao [Shanghai Jiao Tong Univ. (China). Inst. of Refrigeration and Cryogenics

2008-07-01

303

Calculation of conversion coefficients Hp(3)/K air using the PENELOPE Monte Carlo code and comparison with MCNP calculation results; Calcul des coefficients de conversion H{sub p}(3)lK{sub air} au moyen du code de monte-carlo penelope et comparaison avec les resultats de calculs MCNP  

Energy Technology Data Exchange (ETDEWEB)

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

Daures, J.; Gouriou, J.; Bordy, J.M. [CEA Saclay, LIST, Laboratoire National Henri Becquerel (LNE-LNHB), 91 - Gif-sur-Yvette (France)

2010-07-01

304

A Tourism Conditions Index  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

305

Smooth tail index estimation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Both parametric distribution functions appearing in extreme value theory - the generalized extreme value distribution and the generalized Pareto distribution - have log-concave densities if the extreme value index gamma is in [-1,0]. Replacing the order statistics in tail index estimators by their corresponding quantiles from the distribution function that is based on the estimated log-concave density leads to novel smooth quantile and tail index estimators. These new estima...

Mu?ller, Samuel; Rufibach, Kaspar

2006-01-01

306

Air filters; Air filter  

Energy Technology Data Exchange (ETDEWEB)

Efforts for improving the collection efficiency of air filters began with the HEPA (high efficiency particulate air) filter for clean rooms in the semiconductor industry. Now, a ULPA (ultra low penetration air) filter has come into being, capable of dealing with 0.1{mu}m-large particulates, and studies are under way for a super ULPA or others capable of dust collection on the nanometer scale. The method generally used for enhancing filter material efficiency increases the number of fibers by making them finer in diameter, but this method also increases pressure loss. An improved method increases the amount of filter material without changing the diameter, which increases the handling capacity provided the rate remains the same of the fine dust travelling through the filter. Improvement on the folding of filter material or the use of materials lower in pressure loss should also be used jointly with the above-said measures. The latest filter is only 1/4 of the conventional ones in size and weight, which is attributed to the success in collection efficiency improvement and pressure loss reduction. Although the air filter aims primarily to collect fine dust, studies are under way to apply it for the control of chemical substances and for the cleaning of air at residential houses (against ticks and pollen). Used filters are buried as is or after incineration and compaction, or cleaned for reuse, but reconsideration needs be made about these methods of disposal. 6 refs., 4 figs., 4 tabs.

Takahashi, K. [Nippon Muki Co. Ltd., Tokyo (Japan)

1998-06-05

307

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.

Nations, United

308

Definitions and Methodological Issues Regarding Airline Network Concentration Indexes  

Directory of Open Access Journals (Sweden)

Full Text Available This work aims to develop a review of recent articles regarding concentration of airline networks. Here I discuss the main concentration indexes proposed by recent papers and balance its advantages and disadvantages, with the aim of highlighting the effect that indexes have on the direction of air transportation policies.[Paper in Portuguese

Leandro Capitani

2009-01-01

309

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.

2012-04-01

310

Indexing Editorial Cartoons.  

Science.gov (United States)

Discusses access to editorial cartoons, including the importance and worth of editorial cartoons; sources, including newspapers, museums, and special cartoon collections; indexing and classification; subject access; indexing by illustrator and subject; technology and access, including digital data; access to special collections; and access to…

Chapple-Sokol, Angie

1996-01-01

311

TIGR Drosophila Gene Index  

Science.gov (United States)

The Institute for Genomic Resources (TIGR) placed online the Drosophila Gene Index (version 1.1) in 1999. The index is searchable by nucleotide or protein sequence, identifier (TC, ET, EST, GB), tissue, or gene product name. Note that this resource is available free of charge "only to researchers at non-profit institutions using it for non-commercial purposes."

312

TIGR Tomato Gene Index  

Science.gov (United States)

The Institute for Genomic Resources (TIGR) placed online the Tomato Gene Index (version 1.2) in 1999. The index is searchable by nucleotide or protein sequence, identifier (TC, ET, EST, GB), tissue, or gene product name. Note that this resource is available free of charge "only to researchers at non-profit institutions using it for non-commercial purposes."

313

Eccentric connectivity index  

CERN Document Server

The eccentric connectivity index $\\xi^c$ is a novel distance--based molecular structure descriptor that was recently used for mathematical modeling of biological activities of diverse nature. It is defined as $\\xi^c (G) = \\sum_{v \\in V (G)} deg (v) \\cdot \\epsilon (v)$\\,, where $deg (v)$ and $\\epsilon (v)$ denote the vertex degree and eccentricity of $v$\\,, respectively. We survey some mathematical properties of this index and furthermore support the use of eccentric connectivity index as topological structure descriptor. We present the extremal trees and unicyclic graphs with maximum and minimum eccentric connectivity index subject to the certain graph constraints. Sharp lower and asymptotic upper bound for all graphs are given and various connections with other important graph invariants are established. In addition, we present explicit formulae for the values of eccentric connectivity index for several families of composite graphs and designed a linear algorithm for calculating the eccentric connectivity in...

Ili?, Aleksandar

2011-01-01

314

A new supersymmetric index  

International Nuclear Information System (INIS)

Witten's index has been an effective tool in addressing questions of supersymmetry breaking. It is natural to ask if there are other 'index-like' objects which can be computed exactly and provide further insight into the structure of supersymmetric theories. In this work such an index is reported. The index is related to the geometry of the vacua and satisfies an exact differential equation as a function of ?. For integrable theories the index can also be computed thermodynamically by using the exact S-matrix. The equivalence of these two results implies a highly non-trivial equivalence of a set of coupled integral equations with these differential equations, among them Painleve III and the affine Toda equations. 56 refs

1992-07-31

315

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

2007-01-01

316

The human protein index  

Energy Technology Data Exchange (ETDEWEB)

The feasibility of constructing a human protein index and the data base associated with it is discussed. The index would be used to explore molecular anatomy and pathology of human cells. At present, the index is closely tied to the only technique that provides the requisite resolution: two-dimensional electrophoresis. Mapping of human cells, tissues and body fluids together with the mapping of micro-biopsy samples of tissues from individuals with many different diseases should create a systematic description of disease at the protein level. (JMT)

Anderson, N.G.; Anderson, L.

1982-01-01

317

Smooth tail index estimation  

CERN Document Server

Both parametric distribution functions appearing in extreme value theory - the generalized extreme value distribution and the generalized Pareto distribution - have log-concave densities if the extreme value index is between -1 and 0. Replacing the order statistics in tail index estimators by their corresponding quantiles from the distribution function that is based on the estimated log-concave density leads to novel smooth quantile and tail index estimators. Monte Carlo simulations suggest that these new estimators are highly accurate and well superior to their non-smoothed counterparts.

Müller, S; M\\"uller, Samuel; Rufibach, Kaspar

2006-01-01

318

Windchill Temperature (WCT) Index  

Science.gov (United States)

... NWS Offices Key NWS Contacts DAPM/OPL List Hydro Reps Map ... Windchill Temperature (WCT) index uses advances in science, technology, and computer modeling to provide an accurate, understandable, ...

319

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.

Foundation, Wgbh E.

2011-10-25

320

Low-index discontinuity terahertz waveguides.  

Science.gov (United States)

A new type of dielectric THz waveguide based on recent approaches in the field of integrated optics is presented with theoretical and experimental results. Although the guiding mechanism of the low-index discontinuity (LID) THz waveguide is total internal reflection, the THz wave is predominantly confined in the virtually lossless low-index air gap within a high-index dielectric waveguide due to the continuity of electric flux density at the dielectric interface. Attenuation, dispersion and single-mode confinement properties of two LID structures are discussed and compared with other THz waveguide solutions. The new approach provides an outstanding combination of high mode confinement and low transmission losses currently not realizable with any other metal-based or photonic crystal approach. These exceptional properties might enable the breakthrough of novel integrated THz systems or endoscopy applications with sub-wavelength resolution. PMID:19529388

Nagel, Michael; Marchewka, Astrid; Kurz, Heinrich

2006-10-16

 
 
 
 
321

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

In verschillende onderzoeken is er behoefte aan een geautomatiseerde methode voor het bepalen van de dosis ten gevolge van externe bestraling door radionucliden in en op de bodem. Hierbij kan gedacht worden aan migratie van fallout in de bodem, berekenen van de afschermende werking van de bodem bij het opbrengen van een afdeklaag over een laag ertsafval en het dosistempo door de natuurlijke aanwezigheid van radionucliden. In het kader van een onderzoek naar het gebruik...

Ro, Blaauboer

2012-01-01

322

Hydrophytometeorological indexes of Virginia type tobacco  

Directory of Open Access Journals (Sweden)

Full Text Available The field trial of Virginia type tobacco (Hevesi-9 was set in irrigation conditions, in the vicinity of Brzi Brod village, Nišava River's valley, on the alluvium soil type. Water consumption for evapotranspiration, at the irrigated variant and the control one, was calculated for each month and the whole vegetation period, by making the balance between water consumption from the soil layer to 2m under the ground, total precipitation amount in the vegetation and water added by irrigation. Hydro-phyto-meteorological indexes of Virginia type tobacco were calculated in regard to air temperature, relative air humidity, air humidity deficiency, sunshine duration and global radiation. Among the six meteorological elements (the above mentioned five and wind speed analyzed in the studied period, the highest level of correlation with tobacco ETP was shown by air temperature (r=0.88, so the use of hydro-phytotermic index could be recommended for calculation of potential evapotranspiration in irrigation practice.

Aksi? Miroljub

2008-01-01

323

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.

324

Concurrency Control for Adaptive Indexing  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 adapt...

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

2012-01-01

325

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.

1997-01-01

326

Scrophulariaceae Names Index  

Science.gov (United States)

The Natural History Museum in London (UK) offers this Scrophulariaceae Names Index as part of a larger, developing Scrophulariaceae Information System. Featuring one of the weirdest and most interesting of plant Families (the Scrophulariaceae), this preliminary list currently contains some 21,000 names, mainly species binomials. Also to be included in the database are names of species in closely related families reflecting historic changes in taxonomic classification. To begin using the searchable Scrophulariaceae Names Index, first click on the "additional Information" link; then enter the Genus and Species names (or the first letter of each). Typical returns include reference information, sorted by scientific species name.

327

The Bibliographical Star Index  

International Nuclear Information System (INIS)

The Bibliographical Star Index tries to solve the problem of retrieving the observations or any kind of notes about a star. The retrieval program lists all the papers with authors, references and full title in which a given star is cited. (Auth.)

1981-07-10

328

Index: FOI Reports.  

Science.gov (United States)

This cumulative index provides a listing, by topic, of the following Freedom of Information Center reports: reports 1 through 340, summary papers S1 through S38, and opinion papers 001 through 0017. Subject titles include, among many others, "Academic Freedom,""Book Censorship,""Consumer Protection,""Gag Orders,""Press Councils,""TV News," and…

Atkins, Jeanni

329

The Psychological Growth Index  

Science.gov (United States)

The Psychological Growth Index, a true-false questionnaire of 140 items, has been administered to 7,500 individuals in the 14 to 22 age group to distinguish psychologically mature adolescents from less-fully mature peers. Author claims after careful statistical scrutiny instrument remains clinically valid. (DS)

Nixon, Robert E.

1972-01-01

330

Index Rivers ICD4  

1 Salmon and sea trout Index river monitoring: Annual and `real-time' stock status report. 1. Introduction Seven `monitored' rivers in England and Wales (E&W) provide annual run (or `returning stock estimates') for adult salmon. These estimates are derived from automatic fish counters and/or…

331

Infinitesimal index: cohomology computations  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this note several computations of equivariant cohomology groups are performed. For the compactly supported equivariant cohomology, the notion of infinitesimal index developed in arXiv:1003.3525, allows to describe these groups in terms of certain spaces of distributions arising in the theory of splines. The new version contains a large number of improvements.

Concini, Corrado; Procesi, Claudio; Vergne, Michele

2010-01-01

332

Internet Intelligence Index  

Science.gov (United States)

Compiled by competitive intelligence firm Fuld & Company, the Internet Intelligence Index is a compilation of sites useful in gathering competitor and marketplace information on the Internet. All links are annotated and organized by subjects ranging from legal resources to patents and industry-specific information. Additional information on the field of competitive intelligence in general is available on site.

1998-01-01

333

Infinitesimal index: cohomology computations  

CERN Document Server

In this note several computations of equivariant cohomology groups are performed. For the compactly supported equivariant cohomology, the notion of infinitesimal index developed in arXiv:1003.3525, allows to describe these groups in terms of certain spaces of distributions arising in the theory of splines.

De Concini, Corrado; Vergne, Michele

2010-01-01

334

Characterization of the refractive index in gradient-index elements  

Directory of Open Access Journals (Sweden)

Full Text Available The paper is focused on measurement techniques of gradient-index elements particularly useful for slightly inhomogeneous glasses from small laboratory melts. A construction of the measurement cuvette and dependence of the refractive index of an immersion liquid on its parameters is discussed. The dependence of the refractive index of ?-bromonaphtalene on temperature for ? = 0.6328 ?m is described. A measuring method of the refractive index profile of gradient-index elements is presented.

Dariusz Litwin

2008-01-01

335

Automatic Indexing of Full Texts.  

Science.gov (United States)

Demonstrates efficiency of preparation of query description using semantic analyser method based on analysis of semantic structure of documents in field of automatic indexing. Results obtained are compared with automatic indexing results performed by traditional methods and results of indexing done by human indexers. Sample terms and codes are…

Jonak, Zdenek

1984-01-01

336

Index of sampling and analytical methods for multimedia monitoring  

International Nuclear Information System (INIS)

This index is a key component of the Power Plant Inegrated Systems-Chemical Emissions Studies (PISCES) project. The index is a compilation of relevant information, including capabilities and limitations of sampling and analytical methods used to measure trace chemicals in power plant air, water, and solid byproduct discharge streams. The information was gathered from an extensive literature search of ten databases and over 1,500 citations. The information will help utility personnel select appropriate measurement methods

1993-01-01

337

Phrase searching in text indexes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Phrase searching in text indexes Compare different approaches to perform phrase searching, and consider a new approach whereas bigrams is considered as index term. This master thesis focus at the challenges within phrase searching in large text indexes, and to assess alternative approaches to cope with such indexes. This goal was achieved by performing an experiment, based on the theory of using bigrams consisting of stopwords as additional index terms. Realizing the characteristics...

2008-01-01

338

Phrase searching in text indexes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Phrase searching in text indexes Compare different approaches to perform phrase searching, and consider a new approach whereas bigrams is considered as index term. This master thesis focus at the challenges within phrase searching in large text indexes, and to assess alternative approaches to cope with such indexes. This goal was achieved by performing an experiment, based on the theory of using bigrams consisting of stopwords as additional index terms. Realizing the characteristics withi...

2008-01-01

339

Comparing the Palmer Drought Index and the Standardized Precipitation Index for Zagreb-Gric Observatory  

Science.gov (United States)

Conventional Palmer Drought Index (PDSI) and recent Standardized Precipitation Index (SPI) are compared for Zagreb-Gric weather station. Historical time series of PDSI and SPI are compared. For that purpose monthly precipitation, air temperature and air humidity data for Zagreb-Gric Observatory and period 1862-2010 are used. The results indicate that SPI is simpler for interpretation than PDI. On the other side, lack of temperature within SPI, make impossible use of it on climate change applications. Further development of both indices is required. Possible applications of them in irrigation scheduling system is considered as well for drought risk assessment. In addition, a comparison of PDSI and SPI for the periods from 1 to 24 months indicate the best agreement between PDSI and SPI for the periods from 6 to 12 months.

Pandzic, Kreso

2014-05-01

340

Isolated intrathoracic injury with air bag use.  

Science.gov (United States)

The restrained (air bag and seatbelt) driver of a vehicle involved in a high-speed motor-vehicle accident sustained a tear of the thoracic aorta with no signs of external injury. Air bag deployment may mask significant internal injury, and a high index of suspicion is warranted in such situations. PMID:10155430

Sama, A E; Barnaby, D P; Wallis, K J; Gadaleta, D; Hall, M H; Nelson, R L; Naidich, J; Ward, R J

1995-01-01

 
 
 
 
341

Index of Learning Styles  

Science.gov (United States)

The Index of Learning Styles (ILS) is an on-line instrument used to assess preferences in four dimensions (active/reflective, sensing/intuitive, visual/verbal, and sequential/global) of a learning style model formulated by Richard M. Felder and Linda K. Silverman. The ILS results provide an indication of an individual's learning preferences while also providing an even better indication of the preference profile of a group of students (a class).

Felder, Richard M.; Silverman, Linda K.; University, North C.

342

[Disability evaluation: Barthel's index].  

Science.gov (United States)

In Public Health exists a growing tendency to evaluate the impact of health problems both on the quality of life of the persons involved as well as the use of health services. In this sense, the evaluation of incapacity is acquiring ever greater relevance. The Barthel Index is an instrument widely used to this end and measures the capacity of the person for the execution of ten basic activities in daily life, obtaining a quantitative estimation of the subject's level of dependency. The Barthel Index has been used, since its introduction in 1955, resulting in numerous versions, as well as serving as a standard of comparison with other scales. It is an easily applicable method, with a high level of reliability and validity, capable of detecting changes, easy to interpret and the application of which is not problematic. On the other hand, its adaptation to different cultural environments is almost immediate. Although it has a few limitations, the Barthel Index may be recommended as a selection method for measuring physical incapacity, both in clinical practice as well as in epidemiological investigation and Public Health. PMID:9546856

Cid-Ruzafa, J; Damián-Moreno, J

1997-01-01

343

[Seedling index of Salvia miltiorrhiza and its simulation model].  

Science.gov (United States)

Through the correlation analysis on the quantitative traits and their ratios of Salvia miltiorrhiza seedlings and seedling quality, a series of representative indices reflecting the seedling quality of the plant species were determined, and the seedling index suitable to the S. miltiorrhiza seedlings was ascertained by correlation degree analysis. Meanwhile, based on the relationships between the seedling index and the air temperature, solar radiation and air humidity, a simulation model for the seedling index of S. miltiorrhiza was established. The experimental data of different test plots and planting dates were used to validate the model. The results showed that the root diameter, stem diameter, crown dry mass, root dry mass, and plant dry mass had significant positive relationships with the other traits, and could be used as the indicators of the seedling's health. The seedling index of S. miltiorrhiza could be calculated by (stem diameter/root diameter + root dry mass/crown dry mass) x plant dry mass. The stem diameter, root dry mass, crown dry mass and plant dry mass had higher correlations with the seedling index, and thus, the seedling index determined by these indicators could better reflect the seedling's quality. The coefficient of determination (R2) between the predicted and measured values based on 1:1 line was 0.95, and the root mean squared error (RMSE) was 0.15, indicating that the model established in this study could precisely reflect the quantitative relationships between the seedling index of S. miltiorrhiza and the environmental factors. PMID:23359940

Huang, Shu-Hua; Xu, Fu-Li; Wang, Wei-Ling; Du, Jun-Bo; Ru, Mei; Wang, Jing; Cao, Xian-Yan

2012-10-01

344

Polarization entanglement with GRaded-INdex lenses  

CERN Document Server

A novel optical device based on the integration of a GRaded-INdex (GRIN) rod lens and a single mode optical fiber is presented. We show that this system, characterized by a remarkable easiness of alignment and allowing high coupling efficiency of single mode radiation, preserves the polarization entanglement of 2-photon states generated by spontaneous parametric down conversion. We also demonstrate that the use of two equal integrated systems, separated by a free air space, determines very low transmission losses. Hence this device is suitable to inter-connect different sides of complex optical circuits operating with photons entangled in various degrees of freedom, such as polarization and spatial momentum.

Vallone, Giuseppe; De Martini, Francesco; Mataloni, Paolo

2009-01-01

345

Buffering of index structures  

Science.gov (United States)

Buffering the index structures is an important problem, because disk I/O dominates the cost of queries. In this paper, we compare existing algorithms for uniform, nonuniform static and nonuniform dynamic access patterns. We experimentally show that the LRU-2 method is better than the other methods. We also propose an efficient implementation of the LRU-2 algorithm. In the second part of the paper, we propose a new buffering algorithm for a distributed system where each machine has its own buffer. We show experimentally that this method performs better than other buffering techniques.

Yavuz, Tuba; Kahveci, Tamer; Singh, Ambuj K.

2000-10-01

346

Remote Sensing | Indexing &  

...AGORA (FAO) CAB Abstracts (CABI) COMPENDEX (Elsevier) Current Contents - Physical, Chemical & Earth Sciences ( Thomson Reuters) DOAJ - Directory of Open Access Journals Energy & Power Source (EBSCO) Engineering Source (EBSCO) INSPEC (IET) Journal Citation Report (Thomson Reuters) SCIE - Science Citation Index Expanded ...Science (Thomson Reuters) Full-text Archives CLOCKSS (Digital Archive System) e-Helvetica (Swiss National Library Archive) LOCKSS (Lots of Copies Keep Stuff Safe) Content Aggregators EBSCOhost (EBSCO Publishing) J-Gate (Informatics India) Remote Sens. EISSN 2072-4292 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table ...

347

Index theory and Groupoids  

CERN Multimedia

This paper collects the notes of a serie of lectures given by the two authors during the summer school "Geometric and topological methods for Quantum Field Theory" at Villa de Leyva, Colombia, summer 2007. These lecture notes are mainly devoted to a proof using groupoids and $KK$-theory of Atiyah-Singer index theorem on compact smooth manifolds. We will present an elementary introduction to groupoids, $C^*$-algebras, $KK$-theory and pseudodifferential calculus on groupoids. We will finish by showing that the point of view adopted here generalizes to the case of conical pseudo-manifolds.

Debord, Claire

2008-01-01

348

Remarks on the Balaban Index  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this paper we compute some bounds of the Balaban index and then by means of group action we compute the Balaban index of vertex transitive graphs. ACM Computing Classification System (1998): G.2.2 , F.2.2.

Ghorbani, Modjtaba

2013-01-01

349

Alberta oil sands index. Glossary  

Energy Technology Data Exchange (ETDEWEB)

This glossary is a list of keywords used in the Alberta Oil Sands Index (AOSI), including a definition or statement of how the keyword is used for most terms. For this index, it is understood that oil sands consists of bitumen impregnated sands, often called tar sand, bituminous sand, carbonaceous rock, or oil-impregnated rock. The index contains all published information on oil sands, indexed by keywords, categories and weights. Descriptions are given of the subject categories used and the weight system.

1989-01-01

350

Index Sets and Vectorization  

Energy Technology Data Exchange (ETDEWEB)

Vectorization is data parallelism (SIMD, SIMT, etc.) - extension of ISA enabling the same instruction to be performed on multiple data items simultaeously. Many/most CPUs support vectorization in some form. Vectorization is difficult to enable, but can yield large efficiency gains. Extra programmer effort is required because: (1) not all algorithms can be vectorized (regular algorithm structure and fine-grain parallelism must be used); (2) most CPUs have data alignment restrictions for load/store operations (obey or risk incorrect code); (3) special directives are often needed to enable vectorization; and (4) vector instructions are architecture-specific. Vectorization is the best way to optimize for power and performance due to reduced clock cycles. When data is organized properly, a vector load instruction (i.e. movaps) can replace 'normal' load instructions (i.e. movsd). Vector operations can potentially have a smaller footprint in the instruction cache when fewer instructions need to be executed. Hybrid index sets insulate users from architecture specific details. We have applied hybrid index sets to achieve optimal vectorization. We can extend this concept to handle other programming models.

Keasler, J A

2012-03-27

351

Open Budget Index  

Science.gov (United States)

Around the world different governments provide different levels of information about their national budgets, and for some parties, this is a real area of concern. For those interested in this timely subject, the Center of Budget and Policy Priorities has created the Open Budget Index. Released in October 2006, this index rates countries on how open their budget books are to their citizens. As the site notes, this information can help a variety of groups "identify meaningful budget reforms needed in specific countries to combat corruption and strengthen basic services to improve people's lives." A great way to start on the site is by looking through country profiles from Uganda, Mexico, and India that will let concerned parties know specifically how budget transparency improves people's lives. After that, visitors can scroll down through a complete list of country summaries and questionnaires from Albania to Zambia. Visitors should also be aware that many of the materials on the site are available in a number of languages, including Arabic, French, Russian, and Spanish.

352

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

353

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

354

Gamers versus the Index  

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents an ethnographic study of pupils within a trial programme (P2, aimed at developing an upper secondary education for so-called ‘gamers’ who had ‘dropped out’ of school. It was done to follow up a previous trial programme (P1, since many young persons have problems with school. The main question examined here is: When we found situations where the learning worked, by means of social responsitivity, what components were active? How were meaningful affordances created? The trials may be understood from a historical perspective on orality and literacy. Print enabled words to be embedded in space as indexes (tables, lists etc rather than in time (as orality implies. The index is practiced at the core of traditional school today, with attendance lists and schedules (controlling time and space and schoolbooks (finalizing the word. Digital culture challenges these structures where the word is not as finalized, and literacy may include other modalities than writing. School is a culture conservative context, which fights back this transformation with more control, through the use of indexes and constraints on digital culture. As contrast, P2 replaced the schedule with full workdays. This enabled the use of commercial off-the-shelf (COTS computer games, especially massively multiplayer online (MMO games, as replacement for schoolbooks (not all books. The study is based on interviews with the pupils as well as daily participatory observations for two years. Further, data about attendance over two years and grades at the start and end of P2 are presented. The results show that most of the pupils returned to school, became interested in learning again and got grades. They expressed a sense of freedom, which is closely related to the voluntary aspect of playing a game. In other words, to do things for the sake of the actitivity itself, rather than some external learning goal. The paper concludes with a comparison between P2 and traditional school, based upon the study and suggests future research. A review of related research is also included.

2013-01-01

355

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 SciELO Public Health | Language: Spanish Abstract in spanish 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.

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

356

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 SciELO Spain | Language: Spanish Abstract in spanish 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.

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

357

Favorableness-Reality Index  

Directory of Open Access Journals (Sweden)

Full Text Available By constructing a systematic structure of processes, decision models would give the most comprehensive and appropriate decision out of the variety of choices. As an instance, Analytic Hierarchy Process model (AHP has helped to perfect interpretation and systematic decision. Application of this model in control process and evaluation of organization performance were investigated. The opinion of senior chief managers and mid managers about organizational priorities in terms of plan's elements and organizational politicians was gathered via inquiring forms and real performance was specified. The results were analyzed by AHP model and finally, Favorableness-Reality Index (FRI was defined for performance evaluation. For instance, implementation plan of quality management system in a consulting firm was perused.

Mahmoud Ahmadinejad

2008-01-01

358

Environmental Sustainability Index  

Science.gov (United States)

A collaboration among the World Economic Forum's Global Leaders for Tomorrow Environment Task Force, The Yale Center for Environmental Law and Policy, and the Columbia University Center for International Earth Science Information Network (CIESIN), the Environmental Sustainability Index (ESI) "is a measure of overall progress towards environmental sustainability, developed for 122 countries." The ESI is based on 22 core "indicators," each of which combines two to six variables for a total of 67 underlying variables. The idea is to create cross-national comparisons of environmental progress as part of an effort to foster a more analytically driven approach to environmental decision-making. The top-ranked nations were Finland, Norway, and Canada, with the US coming in at number eleven and the UK placing sixteenth. Visitors can view the rankings and download the full text of the 225-page report and a Powerpoint Presentation at the site. A spreadsheet of the ESI is promised for the near future.

2000-01-01

359

Guidelines for preparing subject indexes  

Directory of Open Access Journals (Sweden)

Full Text Available Subject indexes are defined by international standards such as ISO 999 and ANSI Z39.4. These determine the functions that must be implemented in an index in order to give the information seeker an effective means for searching information inside a document. This functionality relies upon the structure and arrangement of index and is also affected by the quality of translation of contents into headings. The structure elements with their scope and the most common alphabetical arrangement are described thoroughly. Since time for index building is limited, the indexer should comply with guidelines that enable quick acquaintance with document contents and translation into headings. The indexer must also pay attention to selection and specificity of headings and depth of indexing.

Jure Bricelj

2008-01-01

360

Thermal comfort and cold air distribution  

Energy Technology Data Exchange (ETDEWEB)

Cold air distribution systems supply air at temperatures between 38 F and 51 F. Cold air distribution systems are increasingly attractive when used in conjunction with ice storage systems to shave peak load by shifting the demand to off-peak hours. They also require less operating and capital costs because they use smaller fans, ducts, piping, and pumps. However, an important issue in design and application of cold air systems is the effect on occupant comfort. There are several techniques and methodologies that practitioners use for evaluation of conventional air distribution systems. Among these is the Air Diffusion Performance Index (ADPI). It is widely used in the US and is referenced in the 1993 ASHRAE Handbook--Fundamentals. However, this technique is based on empirical correlations obtained from tests conducted with conventional systems and it cannot be guaranteed that they will be equally applicable to cold air systems. This study was undertaken, therefore, to extend the existing techniques (especially the Air Diffusion Performance Index) to applications where cold air distribution systems are utilized. This work presents a critical review of the evolution of the ADPI technique and offers several recommendations for developing a firm foundation for future room air distribution research.

Hassani, V. [National Renewable Energy Lab., Golden, CO (United States); Miller, P.L. [Miller (Paul), Arvada, CO (United States)

1998-10-01

 
 
 
 
361

Air Abrasion  

Science.gov (United States)

... information you need from the Academy of General Dentistry Tuesday, May 27, 2014 About | Contact InfoBites Quick ... general dentist, who has been trained in restorative dentistry techniques, will perform any procedures that use air- ...

362

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

363

Radioecological indexes of fallout measurements from the Fukushima nuclear accident  

Science.gov (United States)

Fallout from the Fukushima nuclear accident has been monitored for about 1 month in Thessaloniki, Northern Greece. Three different radionuclides, one short-lived, one relatively long-lived and one long- lived fission product were identified in air, grass and milk samples. The 131I, 137Cs and 134Cs activity concentrations in air reached 497, 145 and 126 ?Bqm?3, respectively on 4 April, 2011. These radionuclides are of particular concern regarding their transfer from the environment to population through the ingestion pathways for the assessment of the Fukushima accident consequences. Radioecological indexes (eco-indexes) of fallout measurements in the air-grass-cow-milk-man pathway for 131I were determined, as they are related to radiological impact of the Fukushima derived radionuclides on the public and environment.

Manolopoulou, Metaxia; Stoulos, Stylianos; Ioannidou, Alexandra; Vagena, Eleni

2014-05-01

364

High Speed Solar Wind Influence on NAO Index and Surface Temperature on Earth  

Science.gov (United States)

The most important role in the atmospheric circulation in the Northern hemisphere plays the North Atlantic Oscillation (NAO). The NAO index changes the surface air temperature in a typical pattern. This research is about high speed solar wind streams (HSSWS) and their influence on the atmospheric circulation. The NAO index increases when a HSSWS reaches the Earth in all studied cases and this leads to typical surface air temperature changes in short term scale.

Asenovska, Yana

2014-03-01

365

Air Pollution and Cardiovascular System  

Directory of Open Access Journals (Sweden)

Full Text Available Air pollution is one of the environmental problems that threaten the public health. The air is a gas mixture. Air pollution is defined as the existence in the amount of pollutants harmful to humans and other organisms in the atmosphere as a result of the natural or human activity thereby changing to the gas rates in the air. The negative effects of pollution-causing particles on the health are closely related to the chemical structure of particles, whether causing a fibrotic reaction, whether having an amorphous shape and the aerodynamic diameters of particles. The particles larger than 10 microns in aerodynamic diameter can not reach up to the alveoli, and can be removed by mucociliary system. If the particles are smaller than 10 microns, these particles can reach to the alveoli, and are closely associated with the cardiovascular mortality and morbidity. The concentration of these particles (PM10 is used as an indicator of pollution, and creates the basis for air quality index. Air pollution has several negative effects such as blood pressure changes, atherosclerosis, endothelial dysfunction, autonomic dysfunction, inflammation, oxidative stress etc. In this review, the effects of air pollution on the cardiovascular system will be examined, and the importance of this issue will be emphasized. [TAF Prev Med Bull 2011; 10(1.000: 97-106

Ejder Kardesoglu

2011-02-01

366

Nuclear Energy Standards. KWIC index  

Energy Technology Data Exchange (ETDEWEB)

The KWIC Index is an alphabetical listing that provides rapid identification of NE standards based upon the specific subject areas. This index facilitates identification of a NE standard by major or key words located in the center of the alphabetical index listing. Alphanumerical designations for specific NE standards are shown in the right-hand column. Standards referenced in this listing include those that are active, inactive, or discontinued.

1984-01-01

367

Guidelines for preparing subject indexes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Subject indexes are defined by international standards such as ISO 999 and ANSI Z39.4. These determine the functions that must be implemented in an index in order to give the information seeker an effective means for searching information inside a document. This functionality relies upon the structure and arrangement of index and is also affected by the quality of translation of contents into headings. The structure elements with their scope and the most common alphabetical arrangement are de...

2008-01-01

368

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

369

A generalized Major index statistic  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Inspired by the $k$-inversion statistic for LLT polynomials, we define a $k$-inversion number and $k$-descent set for words. Using these, we define a new statistic on words, called the $k$-major index, that interpolates between the major index and inversion number. We give a bijective proof that the $k$-major index is equidistributed with the major index, generalizing a classical result of Foata and rediscovering a result of Kadell. Inspired by recent work of Haglund and Ste...

Assaf, Sami

2008-01-01

370

Definitions and methodological issues regarding airline network concentration indexes [paper in Portuguese  

Directory of Open Access Journals (Sweden)

Full Text Available This work aims to develop a review of recent articles regarding concentration of airline networks. Here I discuss the main concentration indexes proposed by recent papers and balance its advantages and disadvantages, with the aim of highlighting the effect that indexes have on the direction of air transportation policies.

Leandro M. Capitani

2009-07-01

371

Sprache und Sozio-Oekonomischer Index (Speech and Socioeconomic Index)  

Science.gov (United States)

A comparison of the socioeconomic index of 77 speakers of Dutch, recorded in 40 places, revealed certain correlations between index and individual linguistic behavior, particularly in regard to the speed of articulation, quantity quotient (low vowels/short vowels), pitch modulation, number of relative clauses and passive construction. (Text is in…

Bluhme, Hermann

1976-01-01

372

A Periodontitis Severity Index.  

Science.gov (United States)

A Periodontitis Severity Index (PSI) was developed and then tested in a population of 154 patients attending the University of Mississippi School of Dentistry screening clinic. Patients were grouped by age decade. The premises of the PSI follow: (1) Periodontitis is diagnosed on the concurrence of clinically apparent marginal inflammation and vertical loss of supporting periodontium (the severity of the associated clinical inflammation does not seem to be related to the severity of the tissue loss) and (2) a Schei ruler is used to determine from the radiograph the percentage of bone loss for a tooth surface. For each patient, a 0 to 1 Clinical Inflammation Score (CIS) was determined at the mesial and distal of every tooth. A CIS of 0 reflected no demonstrable clinical inflammation, whereas a CIS of 1 meant that clinical inflammation could be detected. A modified Schei ruler was used to determine the percentage of bone loss at each interproximal site. A Bone Loss Score (BLS) was calculated on a 0 to 10 whole number continuum. A BLS of 0 meant no bone loss, 1 = up to 10%, etc., up to BLS 10 = 90 to 100% loss. The PSI was then calculated for each mesial and distal surface. PSI = BLS X CIS. The PSI could be 0 if either no bone loss could be determined or the gingiva was healthy. In the presence of marginal inflammation, the PSI value was directly proportional to the percentage of bone loss. Mean PSI values were calculated for each age group. The PSI tended to increase with age. The PSI offers several advantages.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3457141

Adams, R A; Nystrom, G P

1986-03-01

373

A comparison of in-air and in-water calibration of a dosimetry system used for radiation dose assessment in cancer therapy  

Directory of Open Access Journals (Sweden)

Full Text Available An accurate calibration of the therapy level radiation dosimetry system has a pivotal role in the accuracy of dose delivery to cancer patients. The two methods used for obtaining a tissue equivalent calibration of the system: air kerma calibration and its conversion to a tissue equivalent value (absorbed dose to water and direct calibration of the system in a water phantom, have been compared for identical irradiation geometry. It was found that the deviation between the two methods remained within a range of 0% to ±1.7% for the PTW UNIDOS dosimetry system. This means that although the recommended method is in-water calibration, under exceptional circumstances, in-air calibration may be used as well.

Arshed Waheed

2010-01-01

374

Employment Cost Index, March 2001  

Science.gov (United States)

The Employment Cost Index "measures changes in compensation costs, which include wages, salaries, and employer costs for employee benefits." Released on April 26, 2001, the Employment Cost Index for March 2001 was 152.5, which shows a rise of 4.1 percent from March 2000.

375

VISCOSITY INDEX OF RAPESEED OIL  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper were determined viscosity index of rapeseed oil using two methods. Viscosity index is calculated from the measured viscosity at 40 and 1000C using ASTM D 2270 and method graphically using ASTM D 341. The viscosity-temperature coefficient of rapeseed oil was calculated from the measured viscosity at 40 and 1000C.

IOANA STANCIU

2011-09-01

376

Maslov index for Hamiltonian systems  

Directory of Open Access Journals (Sweden)

Full Text Available The aim of this article is to give an explicit formula for computing the Maslov index of the fundamental solutions of linear autonomous Hamiltonian systems in terms of the Conley-Zehnder index and the map time one flow.

Alessandro Portaluri

2008-01-01

377

[DNA index and bronchopulmonary neoplasms].  

Science.gov (United States)

The authors take into consideration 40 cases of lung neoplasms in order to see the relationship between DNA index examined by image analysis, and histological grading we deduced from the results that DNA index agrees with the grading and better points out the biological pattern of the neoplasm, beharing differently in each histological type. PMID:8316342

Oddi, G; D'Alessandro, C; Sacripanti, D; Capobasso, G

1993-05-01

378

Indexed Languages and Unification Grammars  

CERN Multimedia

Indexed languages are interesting in computational linguistics because they are the least class of languages in the Chomsky hierarchy that has not been shown not to be adequate to describe the string set of natural language sentences. We here define a class of unification grammars that exactly describe the class of indexed languages.

Burheim, T

1995-01-01

379

Infrared refractive index of diamond  

International Nuclear Information System (INIS)

The refractive index of natural Type IIa diamond is reported for spectral region 2.5--25mm. The data have been filtered to a Herzberger-type dispersion formula with a quality of fit of a few places in the fifth decimal place. The resultant index uncertainty is abut 10-3

1981-01-01

380

Index of Refraction without Geometry  

Science.gov (United States)

This article presents several activities that permit students to determine the index of refraction of transparent solids and liquids using simple equipment without the need for geometrical relationships, special lighting or optical instruments. Graphical analysis of the measured data is shown to be a useful method for determining the index of…

Farkas, N.; Henriksen, P. N.; Ramsier, R. D.

2006-01-01

 
 
 
 
381

Indexing Temporal XML Using FIX  

Science.gov (United States)

XML has become an important criterion for description and exchange of information. It is of practical significance to introduce the temporal information on this basis, because time has penetrated into all walks of life as an important property information .Such kind of database can track document history and recover information to state of any time before, and is called Temporal XML database. We advise a new feature vector on the basis of FIX which is a feature-based XML index, and build an index on temporal XML database using B+ tree, donated TFIX. We also put forward a new query algorithm upon it for temporal query. Our experiments proved that this index has better performance over other kinds of XML indexes. The index can satisfy all TXPath queries with depth up to K(>0).

Zheng, Tiankun; Wang, Xinjun; Zhou, Yingchun

382

New “Informatics” Index Term Category  

Science.gov (United States)

A new category has been added to the AGU index terms to allow indexing of items related to areas such as data management and analysis, large-scale computational experimentation and modeling, and hardware and software infrastructure. Topics included in the “1900 Informatics” category, compiled by representatives of AGU's Earth and Space Science Informatics (ESSI) focus group, include metadata, ontologies, virtual globes, semantic technology, and virtualization. The AGU index terms have many uses. For example, they are the controlled vocabulary for indexing AGU journal papers, book chapters, meeting abstracts, and Eos articles, as well as some external systems and data sets. The vocabulary also forms the basis of AGU’s “virtual journal” subsets, e-mail alerts, and RSS (“Really Simple Syndication”) Web feeds, and is also useful for browsing and searching AGU articles and abstracts. For more information on AGU index terms, visit http://www.agu.org/pubs/indexterms/.

Sears, Jon

2009-10-01

383

Product-cordial index and friendly index of regular graphs  

Directory of Open Access Journals (Sweden)

Full Text Available Let $G=(V,E$ be a connected simple graph. A labeling $f:V to Z_2$ induces two edge labelings $f^+, f^*: E to Z_2$ defined by $f^+(xy = f(x+f(y$ and $f^*(xy = f(xf(y$ for each $xy in E$. For $i in Z_2$, let $v_f(i = |f^{-1}(i|$, $e_{f^+}(i = |(f^{+}^{-1}(i|$ and $e_{f^*}(i = |(f^*^{-1}(i|$. A labeling $f$ is called friendly if $|v_f(1-v_f(0| le 1$. For a friendly labeling $f$ of a graph $G$, the friendly index of $G$ under $f$ is defined by $i^+_f(G = e_{f^+}(1-e_{f^+}(0$. The set ${i^+_f(G | f is a friendly labeling of G}$ is called the full friendly index set of $G$. Also, the product-cordial index of $G$ under $f$ is defined by $i^*_f(G = e_{f^*}(1-e_{f^*}(0$. The set ${i^*_f(G | f is a friendly labeling of G}$ is called the full product-cordial index set of $G$. In this paper, we find a relation between the friendly index and the product-cordial index of a regular graph. As applications, we will determine the full product-cordial index sets of torus graphs which was asked by Kwong, Lee and Ng in 2010; and those of cycles.

Wai Chee Shiu

2012-03-01

384

Dirty air or shelter air  

Energy Technology Data Exchange (ETDEWEB)

The life-saving function of a shelter especially against radioactive radiation depends above all on its ventilation-air filter system. It has to function without a mistake. As the structure itself assures radiation protection only in part even when it has very thick concrete walls and a total protection equipment it does not have any effect when the ventilation-air filter system installation has some defects. Its exact calculation, installation and subsequent permanent control assure optimal protection. The problem concerning the efficiency of the technical installations in shelters and the maintenance of this function is discussed.

Schlesinger, H.

1981-01-01

385

Indoor air quality and energy issues of refrigerant modulating air-conditioning systems in the tropics  

Energy Technology Data Exchange (ETDEWEB)

The concept of refrigerant modulating air-conditioning systems for medium sized office buildings is increasingly becoming popular owing to their simplicity in installation and maintenance as well as the potential to conserve energy. However, it is important to evaluate the issues of ventilation and indoor air quality (IAQ) associated with such systems. In this paper, the results of an integrated IAQ-energy audit of two buildings in Singapore, employing the refrigerant modulating air-conditioning systems are presented and compared with those from conventional central air-conditioning systems. Two different designs of providing the outside air to the occupied zones are considered and it is observed that the design involving a direct connection of the outside air duct to the fan coil units is better than the design that involves supplying the outside air directly into the occupied zones. Key performance parameters such as the ventilation index, air exchange effectiveness characteristics and the energy index of the refrigerant modulating air-conditioning system are comparable to conventional central air-conditioning systems. (Author)

Sekhar, S.C.; Lim, A.H. [Singapore National Univ., Dept. of Building, Singapore (Singapore)

2003-06-01

386

L'index significant (The Pointed Index Finger).  

Science.gov (United States)

In the framework of a study of nonverbal communication, the various meanings attached to the pointed index finger are analyzed. The question is raised as to what extent the findings hold for cultures other than French. (AMH)

Calbris, G.

1979-01-01

387

Habitat Suitability Index Models: Fallfish  

Science.gov (United States)

A review and synthesis of existing information were used to develop riverine and lacustrine habitat models for fallfish (Semotilis corporalis), a freshwater species. The models are scaled to produce an index of habitat suitability between 0 (unsuitable habitat) to 1 (optimally suitable habitat) for freshwater, marine and estuarine areas of the continental United States. Habitat suitability indexes (HSI's) are designed for use with the habitat evaluation procedures developed by the U.S. Fish and Wildlife Service. Also included are discussions of Suitability Index (SI) curves as used in the Instream Flow Incremental Methodology (IFIM) and SI curves available for an IFIM analysis of Fallfish habitat.

Trial, Joan G.; Wade, Charles S.; Stanley, Jon G.; Nelson, Patrick C.

1983-01-01

388

The 3D Indexing Problem  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper discusses the problem of 3D indexing. That is, given a collection of 3D object models (CAD models, formalized as collections of labeled 3D points), an indexing algorithm may perform off-line pre-processing to generate a data structure that allows it to decide quickly whether a given 2D image was contains any of the objects represented by the 3D models. We first review and develop some mathematical machinery. Next, the indexing problem is related to well-known point-location and sea...

Breuel, Thomas M.

1993-01-01

389

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

390

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)

2005-01-01

391

DESCRIPTION OF EVALUATION INDEXES FOR PERFORMANCE OF PHYSICAL EDUCATION TEACHERS  

Directory of Open Access Journals (Sweden)

Full Text Available MIRKAZEMI, S.A. ; ALIYANI, M.H. ; KASHTIDAR, M. ; HEMMATINEZHAD, M.A. Description of evaluation indexes for performance of physical education teachers. Brazilian Journal of Biomotricity. v. 6, n. 1, p. 33-42, 2012. This paper presents evaluation indexes for performance of physical education teachers, because they play a vital role in the training and education. Research society include all of experts in the school sporting affairs , that we select them purposely .we use to research from self-designed question air and its validity byconsensus of experts .we use Alpha cronbach correlation (0.78 for its reliability. Based on the experts opinions (Delphi method, we modify them during four stages. After modifications of each stages, we suggest another modification to them and finally, we reach to a consensus based on the Kendall coefficient (w=0.702 regarding to evaluation indexes. The results show that among 40 proposed indexes. In the 9 dimensions, 8 indexes are very necessary and 4 indexes are less necessary. Teacher evaluation needs to compile standard, thereby we evaluate performances effectively and efficiently. Thus we suggest that reviewin the teachers evaluation system can show our system weaknesses and strengthens and we evaluate teacher's performance efficiently.

Mehr Ali Hemmatinezhad

2012-03-01

392

Refractive Index Compensation in Over-Determined Interferometric Systems  

Directory of Open Access Journals (Sweden)

Full Text Available We present an interferometric technique based on a differential interferometry setup for measurement under atmospheric conditions. The key limiting factor in any interferometric dimensional measurement are fluctuations of the refractive index of air representing a dominating source of uncertainty when evaluated indirectly from the physical parameters of the atmosphere. Our proposal is based on the concept of an over-determined interferometric setup where a reference length is derived from a mechanical frame made from a material with a very low thermal coefficient. The technique allows one to track the variations of the refractive index of air on-line directly in the line of the measuring beam and to compensate for the fluctuations. The optical setup consists of three interferometers sharing the same beam path where two measure differentially the displacement while the third evaluates the changes in the measuring range, acting as a tracking refractometer. The principle is demonstrated in an experimental setup.

Zden?k Buchta

2012-10-01

393

? dependence of the Witten index  

International Nuclear Information System (INIS)

The ?-dependence of the regularized Witten index is commented in supersymmetric quantum mechanics focusing on the problem of periodic boundary conditions and the normalization of the corresponding eigenstates. (Author)

1985-01-01

394

Introduction to indexing and abstracting  

CERN Document Server

Successful information access in the digital information age requires robust systems of indexing and abstracting. This book provides a complete introduction to the subject that covers the many recent changes in the field.

Cleveland, Ana

2013-01-01

395

National Disease and Therapeutic Index.  

Science.gov (United States)

The report describes the National Disease and Therapeutic Index constructed by IMS America, Ltd. NDTI is a statistical compilation of current data on drugs prescribed by physicians in private practice in the United States. The Consumer Safety Statistics S...

J. B. Gatrell

1974-01-01