The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Rongchang Chen - One of the best experts on this subject based on the ideXlab platform.
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measurement of the linear Attenuation Coefficients of breast tissues by synchrotron radiation computed tomography
Physics in Medicine and Biology, 2010Co-Authors: Rongchang Chen, Renata Longo, L Rigon, Fabrizio Zanconati, A De Pellegrin, Fulvia Arfelli, D Dreossi, R H Menk, E VallazzaAbstract:The measurement of the linear Attenuation Coefficients of breast tissues is of fundamental importance in the field of breast x-ray diagnostic imaging. Different groups have evaluated the linear Attenuation Coefficients of breast tissues by carrying out direct Attenuation measurements in which the specimens were thin and selected as homogeneous as possible. Here, we use monochromatic and high-intensity synchrotron radiation computed tomography (SR CT) to evaluate the linear Attenuation Coefficients of surgical breast tissues in the energy range from 15 to 26.5 keV. X-ray detection is performed by a custom digital silicon micro-strip device, developed in the framework of the PICASSO INFN experiment. Twenty-three human surgical breast samples were selected for SR CT and histological study. Six of them underwent CT, both as fresh tissue and after formalin fixation, while the remaining 17 were imaged only as formalin-fixed tissues. Our results for fat and fibrous tissues are in good agreement with the published values. However, in contrast to the published data, our measurements show no significant differences between fibrous and tumor tissues. Moreover, our results for fresh and formalin-fixed tissues demonstrate a reduction of the linear Attenuation coefficient for fibrous and tumor tissues after fixation.
E Vallazza - One of the best experts on this subject based on the ideXlab platform.
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measurement of the linear Attenuation Coefficients of breast tissues by synchrotron radiation computed tomography
Physics in Medicine and Biology, 2010Co-Authors: Rongchang Chen, Renata Longo, L Rigon, Fabrizio Zanconati, A De Pellegrin, Fulvia Arfelli, D Dreossi, R H Menk, E VallazzaAbstract:The measurement of the linear Attenuation Coefficients of breast tissues is of fundamental importance in the field of breast x-ray diagnostic imaging. Different groups have evaluated the linear Attenuation Coefficients of breast tissues by carrying out direct Attenuation measurements in which the specimens were thin and selected as homogeneous as possible. Here, we use monochromatic and high-intensity synchrotron radiation computed tomography (SR CT) to evaluate the linear Attenuation Coefficients of surgical breast tissues in the energy range from 15 to 26.5 keV. X-ray detection is performed by a custom digital silicon micro-strip device, developed in the framework of the PICASSO INFN experiment. Twenty-three human surgical breast samples were selected for SR CT and histological study. Six of them underwent CT, both as fresh tissue and after formalin fixation, while the remaining 17 were imaged only as formalin-fixed tissues. Our results for fat and fibrous tissues are in good agreement with the published values. However, in contrast to the published data, our measurements show no significant differences between fibrous and tumor tissues. Moreover, our results for fresh and formalin-fixed tissues demonstrate a reduction of the linear Attenuation coefficient for fibrous and tumor tissues after fixation.
U Cevik - One of the best experts on this subject based on the ideXlab platform.
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calculation of radiation Attenuation Coefficients effective atomic numbers and electron densities for some building materials
Radiation Protection Dosimetry, 2012Co-Authors: N Damla, Ahmet Duran Celik, Erkan Kiris, Hasan Baltas, U CevikAbstract:: Some building materials, regularly used in Turkey, such as sand, cement, gas concrete (lightweight, aerated concrete), tile and brick, have been investigated in terms of mass Attenuation coefficient (μ/ρ), effective atomic, numbers (Z(eff)), effective electron densities (N(e)) and photon interaction cross section (σ(a)) at 14 different energies from 81- to 1332-keV gamma-ray energies. The gamma rays were detected by using gamma-ray spectroscopy, a High Purity Germanium (HPGe) detector. The elemental compositions of samples were analysed using an energy dispersive X-ray fluorescence spectrometer. Mass Attenuation Coefficients of these samples have been compared with tabulations based upon the results of WinXcom. The theoretical mass Attenuation Coefficients were estimated using the mixture rule and the experimental values of investigated parameters were compared with the calculated values. The agreement of measured values of mass Attenuation coefficient, effective atomic numbers, effective electron densities and photon interaction cross section with the theory has been found to be quite satisfactory.
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assessment of natural radioactivity and mass Attenuation Coefficients of brick and roofing tile used in turkey
Radiation Measurements, 2011Co-Authors: N Damla, U Cevik, A I Kobya, Necati Celik, A Celik, Ibrahim YildirimAbstract:Abstract In this study the distribution of natural radionuclides (226Ra, 232Th, 40K) in brick and roofing tile samples commonly used as building materials in Turkey was measured by using gamma spectrometry. The activity concentrations, radium equivalent activities (Raeq), representative level index, indoor absorbed dose rate in air values and annual effective dose due to the intake of the above-mentioned radionuclides in the brick and roofing tile samples were estimated to assess the radiation hazard for people living in dwellings made of the materials studied. The measured average activity concentrations of 226Ra, 232Th and 40K were 34 ± 14, 34 ± 13 and 462 ± 175 Bq.kg−1, respectively, for brick samples. For roofing tile, the average activity concentrations of 226Ra, 232Th and 40K were measured to be 34 ± 14, 33 ± 12 and 429 ± 161 Bq.kg−1, respectively. The concentrations for these natural radionuclides were compared with the reported data of other countries. The Raeq values of all samples were lower than the limit of 370 Bq.kg−1, equivalent to a gamma dose of 1.5 mSv.a−1 recommended by OECD. This study shows that the measured brick and roofing tile samples do not pose any significant source of radiation hazard and are safe to be used as building materials. Moreover, the experimental mass Attenuation Coefficients (μ/ρ) of brick and roofing tile samples were determined in the energy range 80–1332 keV using the gamma ray transmission method. The experimental mass Attenuation Coefficients were compared with theoretical values obtained using XCOM. It was found that the computed values and the experimental results of this work are in good agreement with those reported in the literature. The chemical compositions and structural analysis (XRD) of the brick and roofing tile samples are also presented.
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radiation dose estimation and mass Attenuation Coefficients of marble used in turkey
Annals of Nuclear Energy, 2010Co-Authors: U Cevik, N Damla, Ahmet Duran Celik, A I Kobya, A KaraAbstract:Abstract In this study the natural radioactivity in marble samples used in Turkey was measured by means of gamma spectrometry. The results showed that the specific activities of 226Ra, 232Th and 40K ranged from 10 to 92 Bq kg−1, from 4 to 122 Bq kg−1 and from 28 to 676 Bq kg−1, respectively. The radiological hazards in marble samples due to the natural radioactivity were inferred from calculations of radium equivalent activities (Raeq), indoor absorbed dose rate in air values, the annual effective dose and gamma and alpha indexes. These radiological parameters were evaluated and compared with the internationally recommended values. The measurements showed that marble samples used in Turkey have low level of natural radioactivity; therefore, the use of these types of marble in dwellings is safe for inhabitants. Mass Attenuation Coefficients (μ/ρ) were obtained both experimentally and theoretically for different marble samples produced in Turkey by using gamma-ray transmission method. Experimental values showed a good agreement with the theoretical values.
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assessment of natural radiation exposure levels and mass Attenuation Coefficients of lime and gypsum samples used in turkey
Environmental Monitoring and Assessment, 2010Co-Authors: N Damla, Ahmet Duran Celik, U Cevik, A I Kobya, Necati CelikAbstract:The activity concentrations of 226Ra, 232Th, and 40K in lime and gypsum samples used as building materials in Turkey were measured using gamma spectrometry. The mean activity concentrations of 226Ra, 232Th, and 40K were found to be 38 ± 16, 20 ± 9, and 156 ± 54 Bq kg − 1 for lime and found to be 17 ± 6, 13 ± 5, and 429 ± 24 Bq kg − 1 for gypsum, respectively. The radiological hazards due to the natural radioactivity in the samples were inferred from calculations of radium equivalent activities (Raeq), indoor absorbed dose rate in the air, the annual effective dose, and gamma and alpha indices. These radiological parameters were evaluated and compared with the internationally recommended limits. The experimental mass Attenuation Coefficients (μ/ρ) of the samples were determined in the energy range 81–1,332 keV. The experimental mass Attenuation Coefficients were compared with theoretical values obtained using XCOM. It is found that the calculated values and the experimental results are in good agreement.
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radiation dose estimation and mass Attenuation Coefficients of cement samples used in turkey
Journal of Hazardous Materials, 2010Co-Authors: N Damla, Ahmet Duran Celik, U Cevik, A I Kobya, Necati Celik, R Van GriekenAbstract:Abstract Different cement samples commonly used in building construction in Turkey have been analyzed for natural radioactivity using gamma-ray spectrometry. The mean activity concentrations observed in the cement samples were 52, 40 and 324 Bq kg −1 for 226 Ra, 232 Th and 40 K, respectively. The measured activity concentrations for these radionuclides were compared with the reported data of other countries and world average limits. The radiological hazard parameters such as radium equivalent activities (Ra eq ), gamma index ( I γ ) and alpha index ( I α ) indices as well as terrestrial absorbed dose and annual effective dose rate were calculated and compared with the international data. The Ra eq values of cement are lower than the limit of 370 Bq kg −1 , equivalent to a gamma dose of 1.5 mSv y −1 . Moreover, the mass Attenuation Coefficients were determined experimentally and calculated theoretically using XCOM in some cement samples. Also, chemical compositions analyses of the cement samples were investigated.
Frank Verhaegen - One of the best experts on this subject based on the ideXlab platform.
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deriving effective atomic numbers from dect based on a parameterization of the ratio of high and low linear Attenuation Coefficients
Physics in Medicine and Biology, 2013Co-Authors: Guillaume Landry, J Seco, Mathieu Gaudreault, Frank VerhaegenAbstract:Dual energy computed tomography (DECT) can provide simultaneous estimation of relative electron density ?e?and effective atomic number Zeff. The ability to obtain these quantities (?e, Zeff) has been shown to benefit selected radiotherapy applications where tissue characterization is required. The conventional analysis method (spectral method) relies on knowledge of the CT scanner photon spectra which may be difficult to obtain accurately. Furthermore an approximate empirical Attenuation correction of the photon spectrum through the patient is necessary. We present an alternative approach based on a parameterization of the measured ratio of low and high kVp linear Attenuation Coefficients for deriving Zeff?which does not require the estimation of the CT scanner spectra. In a first approach, the tissue substitute method (TSM), the Rutherford parameterization of the linear Attenuation Coefficients was employed to derive a relation between Zeff?and the ratio of the linear Attenuation Coefficients measured at the low and high kVp of the CT scanner. A phantom containing 16 tissue mimicking inserts was scanned with a dual source DECT scanner at 80 and 140 kVp. The data from the 16 inserts phantom was used to obtain model parameters for the relation between Zeff?and . The accuracy of the method was evaluated with a second phantom containing 4 tissue mimicking inserts. The TSM was compared to a more complex approach, the reference tissue method (RTM), which requires the derivation of stoichiometric fit parameters. These were derived from the 16 inserts phantom scans and used to calculate CT numbers at 80 and 140 kVp for a set of tabulated reference human tissues. Model parameters for the parameterization of were estimated for this reference tissue dataset and compared to the results of the TSM. Residuals on Zeff?for the reference tissue dataset for both TSM and RTM were compared to those obtained from the spectral method. The tissue substitutes were well fitted by the TSM with R2?= 0.9930. Residuals on Zeff?for the phantoms were similar between the TSM and spectral methods for Zeff < 8 while they were improved by the TSM for higher Zeff. The RTM fitted the reference tissue dataset well with R2 = 0.9999. Comparing the Zeff?extracted from TSM and the more complex RTM to the known values from the reference tissue dataset yielded errors of up to 0.3 and 0.15 units of Zeff?respectively. The parameterization approach yielded standard deviations which were up to 0.3 units of Zeff?higher than those observed with the spectral method for Zeff?around 7.5. Procedures for the DECT estimation of Zeff?removing the need for estimates of the CT scanner spectra have been presented. Both the TSM and the more complex RTM performed better than the spectral method. The RTM yielded the best results for the reference human tissue dataset reducing errors from up to 0.3 to 0.15 units of Zeff?compared to the simpler TSM. Both TSM and RTM are simpler to implement than the spectral method which requires estimates of the CT scanner spectra.
H O Tekin - One of the best experts on this subject based on the ideXlab platform.
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measurement of mass Attenuation Coefficients effective atomic numbers and electron densities for different parts of medicinal aromatic plants in low energy region
Nuclear Science and Techniques, 2018Co-Authors: M I Sayyed, F Akman, Ibrahim Halil Gecibesler, H O TekinAbstract:The mass Attenuation Coefficients (µ/ρ) for different parts (root, flower, stem, and leaf) of three medicinal aromatic plants (Teucrium chamaedrys L. subsp. sinuatum, Rheum ribes, and Chrysophthalmum montanum) were measured using an 241Am photon source in a stable geometry and calculated using the Monte Carlo N-Particle Transport Code System-extended (MCNPX) code and the WinXCOM program. The experimental and theoretical MCNPX and WinXCOM values exhibited good agreement. The measured mass Attenuation coefficient values were then used to compute the effective atomic number (Zeff) and electron density (NE) of the samples. The results reveal that S1-S (stem of Teucrium chamaedrys L. subsp. sinuatum) has the highest values of µ/ρ and Zeff.
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photon Attenuation Coefficients of different rock samples using mcnpx geant4 simulation codes and experimental results a comparison study
Radiation Effects and Defects in Solids, 2018Co-Authors: Shamsan S Obaid, H O Tekin, M I Sayyed, D K Gaikwad, Y Elmahroug, Pravina P PawarAbstract:The photon Attenuation Coefficients for the rocks (Feldspathic basalt, Compact basalt, Volcanic rock, Pink granite, Sandstone and Dolerite) have been investigated using MCNPX and Geant4 codes for p...
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validation of mcnpx with experimental results of mass Attenuation Coefficients for cement gypsum and mixture
Journal of Radiation Protection and Research, 2017Co-Authors: H O Tekin, Viswanath P Singh, Tugba Manici, E E AltunsoyAbstract:Background: Shielding properties of compound or mixture is presented in terms of mass Attenuation Coefficients using Monte Carlo simulation. Mass Attenuation Coefficients of cement, gypsum and the mixture of gypsum and PbCO3 has been investigated using monte carlo MCNPX. Materials and Methods: The mass Attenuation Coefficients of cement, gypsum and the mixture of gypsum and PbCO3 were calculated for photon energies 365.5, 661.6, 1,173.2, and 1,332.5 keV energies. Results and Discussion: The simulated values of mass Attenuation Coefficients were compared avaialable experimental results, theoretical values by XCOM and found good comparability of the results. Conclusion: Standard simulation geometry used in the present investigation would be very useful for various types of sample for shielding and dosimetry applications.
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mcnp x monte carlo code application for mass Attenuation Coefficients of concrete at different energies by modeling 3 3 inch nai tl detector and comparison with xcom and monte carlo data
Science and Technology of Nuclear Installations, 2016Co-Authors: H O TekinAbstract:Gamma-ray measurements in various research fields require efficient detectors. One of these research fields is mass Attenuation Coefficients of different materials. Apart from experimental studies, the Monte Carlo (MC) method has become one of the most popular tools in detector studies. An NaI(Tl) detector has been modeled, and, for a validation study of the modeled NaI(Tl) detector, the absolute efficiency of 3 × 3 inch cylindrical NaI(Tl) detector has been calculated by using the general purpose Monte Carlo code MCNP-X (version 2.4.0) and compared with previous studies in literature in the range of 661–2620 keV. In the present work, the applicability of MCNP-X Monte Carlo code for mass Attenuation of concrete sample material as building material at photon energies 59.5 keV, 80 keV, 356 keV, 661.6 keV, 1173.2 keV, and 1332.5 keV has been tested by using validated NaI(Tl) detector. The mass Attenuation Coefficients of concrete sample have been calculated. The calculated results agreed well with experimental and some other theoretical results. The results specify that this process can be followed to determine the data on the Attenuation of gamma-rays with other required energies in other materials or in new complex materials. It can be concluded that data from Monte Carlo is a strong tool not only for efficiency studies but also for mass Attenuation Coefficients calculations.
