Subjects -> EARTH SCIENCES (Total: 771 journals)     - EARTH SCIENCES (527 journals)    - GEOLOGY (94 journals)    - GEOPHYSICS (33 journals)    - HYDROLOGY (29 journals)    - OCEANOGRAPHY (88 journals) EARTH SCIENCES (527 journals)                  1 2 3 | Last
 Showing 1 - 200 of 371 Journals sorted by number of followers Nature Geoscience       (Followers: 161) IEEE Geoscience and Remote Sensing Letters       (Followers: 149) International Journal of Remote Sensing       (Followers: 144) Earth and Planetary Science Letters       (Followers: 141) Journal of Atmospheric and Solar-Terrestrial Physics       (Followers: 133) Journal of the Atmospheric Sciences       (Followers: 83) Ocean & Coastal Management       (Followers: 62) Marine Policy       (Followers: 60) International Journal of Geographical Information Science       (Followers: 55) Geochimica et Cosmochimica Acta       (Followers: 54) ICES Journal of Marine Science: Journal du Conseil       (Followers: 53) Natural Hazards       (Followers: 53) Journal of Earth System Science       (Followers: 52) Aquatic Conservation Marine and Freshwater Ecosystems       (Followers: 44) Hydrological Processes       (Followers: 44) Estuarine, Coastal and Shelf Science       (Followers: 41) Journal of Hydrologic Engineering       (Followers: 40) Geophysical Journal International       (Followers: 39) Groundwater       (Followers: 37) International Journal of Earth Sciences       (Followers: 37) International Journal of Applied Earth Observation and Geoinformation       (Followers: 36) Physics of the Earth and Planetary Interiors       (Followers: 34) Journal of Atmospheric and Oceanic Technology       (Followers: 33) Geomorphology       (Followers: 33) Chemical Geology       (Followers: 31) Marine Geology       (Followers: 31) Geology Today       (Followers: 31) Marine Environmental Research       (Followers: 31) Journal of Quaternary Science       (Followers: 31) Reviews of Modern Physics       (Followers: 30) Journal of Geotechnical and Geoenvironmental Engineering       (Followers: 30) Journal of Geology       (Followers: 30) Coastal Management       (Followers: 29) Advances In Physics       (Followers: 29) GPS Solutions       (Followers: 28) Bulletin of the Seismological Society of America       (Followers: 26) Landslides       (Followers: 26) Journal of Structural Geology       (Followers: 26) Quaternary Science Reviews       (Followers: 26) Ground Water Monitoring & Remediation       (Followers: 25) Geoforum       (Followers: 25) Earth Surface Processes and Landforms       (Followers: 25) Environmental Geology       (Followers: 25) Tectonophysics       (Followers: 24) Geocarto International       (Followers: 23) Coral Reefs       (Followers: 22) Bulletin of Volcanology       (Followers: 22) Hydrogeology Journal       (Followers: 21) Hydrobiologia       (Followers: 21) Tellus A       (Followers: 21) Marine and Petroleum Geology       (Followers: 21) Water Resources       (Followers: 21) Journal of Plasma Physics       (Followers: 21) Earthquake Spectra       (Followers: 20) Tellus B       (Followers: 20) Journal of Marine Research       (Followers: 20) Sedimentary Geology       (Followers: 20) Dynamics of Atmospheres and Oceans       (Followers: 19) Geophysics       (Followers: 19) Quaternary Research       (Followers: 19) Geological Journal       (Followers: 19) Global and Planetary Change       (Followers: 18) Physics of Metals and Metallography       (Followers: 18) African Journal of Aquatic Science       (Followers: 17) Computational Geosciences       (Followers: 17) Journal of Volcanology and Geothermal Research       (Followers: 17) Natural Hazards Review       (Followers: 16) Geological Magazine       (Followers: 16) The Holocene       (Followers: 16) Atmosphere-Ocean       (Followers: 16) Journal of Metamorphic Geology       (Followers: 15) Journal of Applied Geophysics       (Followers: 15) Journal of Asian Earth Sciences       (Followers: 15) Sedimentology       (Followers: 15) Ocean Development & International Law       (Followers: 15) Applied Geochemistry       (Followers: 14) Quaternary International       (Followers: 14) Journal of the World Aquaculture Society       (Followers: 13) Journal of Hydro-environment Research       (Followers: 13) Pramana       (Followers: 13) Soil Dynamics and Earthquake Engineering       (Followers: 13) Electromagnetics       (Followers: 13) Ocean Modelling       (Followers: 12) European Journal of Mineralogy       (Followers: 12) Frontiers of Earth Science       (Followers: 12) Continental Shelf Research       (Followers: 12) Computers and Geotechnics       (Followers: 12) Arctic, Antarctic, and Alpine Research       (Followers: 12) Pure and Applied Geophysics       (Followers: 12) CATENA       (Followers: 11) Journal of Petrology       (Followers: 11) Ore Geology Reviews       (Followers: 11) Contributions to Mineralogy and Petrology       (Followers: 11) Applied Geophysics       (Followers: 11) Journal of African Earth Sciences       (Followers: 11) IEEE Journal of Oceanic Engineering       (Followers: 11) Marine Mammal Science       (Followers: 10) Cretaceous Research       (Followers: 10) Earth Interactions       (Followers: 10) Australian Journal of Earth Sciences: An International Geoscience Journal of the Geological Society of Australia       (Followers: 10) Bulletin of Earthquake Engineering       (Followers: 10) Gondwana Research       (Followers: 10) Physics of Plasmas       (Followers: 10) Journal of Seismology       (Followers: 9) Physik in unserer Zeit       (Followers: 9) Lithos       (Followers: 9) Limnology       (Followers: 9) Acta Geophysica       (Followers: 9) Journal of Contemporary Physics (Armenian Academy of Sciences)       (Followers: 9) Journal of Marine Systems       (Followers: 9) Geotectonics       (Followers: 9) Facies       (Followers: 9) Comptes Rendus : Geoscience       (Followers: 9) Journal of Geodesy       (Followers: 9) Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards       (Followers: 8) Geophysical & Astrophysical Fluid Dynamics       (Followers: 8) Natural Resources Research       (Followers: 8) Geobiology       (Followers: 8) Quaternary Geochronology       (Followers: 8) Earthquake Engineering and Engineering Vibration       (Followers: 8) Geophysical Prospecting       (Followers: 7) Journal of Systematic Palaeontology       (Followers: 7) Physics of the Solid State       (Followers: 7) Plasma Physics Reports       (Followers: 7) Precambrian Research       (Followers: 7) Ocean Engineering       (Followers: 6) Petrology       (Followers: 6) Applied Clay Science       (Followers: 6) Journal of Sea Research       (Followers: 6) Geochemistry : Exploration, Environment, Analysis       (Followers: 6) Acta Geotechnica       (Followers: 6) Geo-Marine Letters       (Followers: 6) Journal of Coastal Conservation       (Followers: 6) Applied Ocean Research       (Followers: 6) Rock Mechanics and Rock Engineering       (Followers: 6) Chinese Geographical Science       (Followers: 6) Journal of Geodynamics       (Followers: 6) Resource Geology       (Followers: 6) Marine and Freshwater Research       (Followers: 6) Ocean Dynamics       (Followers: 6) International Journal of Geomechanics       (Followers: 6) Island Arc       (Followers: 5) Geofluids       (Followers: 5) Computational Mathematics and Mathematical Physics       (Followers: 5) Marine Geophysical Researches       (Followers: 5) Geochemistry       (Followers: 5) Permafrost and Periglacial Processes       (Followers: 5) Zeitschrift für Geomorphologie       (Followers: 5) Terra Nova       (Followers: 5) Energy Exploration & Exploitation       (Followers: 4) Organic Geochemistry       (Followers: 4) Mineralium Deposita       (Followers: 4) Marine Geodesy       (Followers: 4) Limnologica       (Followers: 4) Meteorologische Zeitschrift       (Followers: 4) Letters in Mathematical Physics       (Followers: 4) Geostandards and Geoanalytical Research       (Followers: 3) Surveys in Geophysics       (Followers: 3) Lithology and Mineral Resources       (Followers: 3) Russian Geology and Geophysics       (Followers: 3) Journal of Oceanology and Limnology       (Followers: 3) JETP Letters       (Followers: 3) Mathematical Physics, Analysis and Geometry       (Followers: 3) Fundamental and Applied Limnology / Archiv fÃ¼r Hydrobiologie       (Followers: 3) Contributions to Plasma Physics       (Followers: 3) Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen       (Followers: 3) Geomagnetism and Aeronomy       (Followers: 3) Journal of Petroleum Science and Engineering       (Followers: 3) Journal of Marine Science and Technology       (Followers: 3) Zeitschrift der Deutschen Gesellschaft für Geowissenschaften       (Followers: 3) Stratigraphy and Geological Correlation       (Followers: 2) Annales Henri Poincaré       (Followers: 2) Rocks & Minerals       (Followers: 2) Newsletters on Stratigraphy       (Followers: 2) Polar Record       (Followers: 2) Mineralogy and Petrology       (Followers: 2) International Journal of Coal Geology       (Followers: 2) Helgoland Marine Research       (Followers: 2) Journal of Geophysics and Engineering       (Followers: 2) Izvestiya, Physics of the Solid Earth       (Followers: 2) Journal of Mining Science       (Followers: 2) Studia Geophysica et Geodaetica       (Followers: 1) The Leading Edge       (Followers: 1) Izvestiya, Atmospheric and Oceanic Physics       (Followers: 1) Doklady Physics       (Followers: 1) Russian Physics Journal       (Followers: 1) Reports on Mathematical Physics       (Followers: 1) Glass Physics and Chemistry       (Followers: 1) Physics of Life Reviews       (Followers: 1) Neues Jahrbuch für Mineralogie - Abhandlungen       (Followers: 1) Russian Journal of Pacific Geology Russian Journal of Mathematical Physics Physics of Wave Phenomena Moscow University Physics Bulletin Moscow University Geology Bulletin Marine Georesources & Geotechnology Journal of Mountain Science Grassland Science Erwerbs-Obstbau Bulletin of the Lebedev Physics Institute

1 2 3 | Last

Similar Journals
 Moscow University Physics BulletinJournal Prestige (SJR): 0.273 Citation Impact (citeScore): 1Number of Followers: 0      Hybrid journal (It can contain Open Access articles) ISSN (Print) 1934-8460 - ISSN (Online) 0027-1349 Published by Springer-Verlag  [2469 journals]
• A New Dosimetric Investigation of a Head Volume Irradiated by Carbon Ions
in the Presence of an Axial Magnetic Field

Abstract: — To improve the irradiation accuracy in hadron therapy, a lot of studies are in the evaluation uncluding how to integrate MRI and PET at the treatment of cancer patients. These two future techniques will offer simultaneously the monitoring of the beam during the irradiation. In this study and for the first time, we calculated the dose distribution in a head volume for several carbon ion energies and at different values of the magnetic field B using fluka MC code. Afterwards, either longitudinal or radial dose deflection was simulated with and without B. Basically, the Z axis is entered by the beam and the radial deflections mean the ones corresponded to the X axis which has the same direction of B. The maximum longitudinal deviation of bragg pick depth was 0.672 mm at 200 MeV and the maximum radial deflection was almost 4.23 cm at 100 MeV. Both of them are in the presence of B = 1.5 T. Our results are in a good agreement with previous experimental results (a maximum relative error founded of 2.08%). The results of this study will offer the monitoring of the dose deposition with good accuracy in the presence of a magnetic field in carbon ion therapy.
PubDate: 2021-12-01

• Monte Carlo Simulation of Accident Scenario Involving the NIAR Radioactive
Sources

Abstract: The consequences of radiological accidents outside the nuclear sector can be fatal. Therefore, emergency response plans must take into consideration the worst scenarios. This article presents a simulation of an accident in which it was assumed that the assembly of cobalt-60 sources from the irradiator installed at National Institute of Agronomic Research (NIAR) of Tangier was found on the ground. The Monte Carlo GEANT4 code was used to estimate the equivalent dose rate in the organs of an individual presented by an anthropomorphic phantom at different distances, and its variance with decreasing activity, this simulation will allow as to make the best decisions, correct actions, prevent serious radiobiological damage and to prepare the best methods of intervention in the occurrence of this scenario.
PubDate: 2021-12-01

• Conversion Coefficients of Local Skin Absorbed Dose per Fluence for
Monoenergetic Electrons and Positrons: An Analytical Approach

Abstract: This study seeks to calculate the conversion coefficients from fluence to local skin absorbed dose $$({\text{LSD/}}\Phi )$$ for monoenergetic electrons and positrons from 0.01 to 10 MeV. The conversion coefficients calculation used a new analytical approach. The obtained results are in good agreement with those previous published. A new analytical fit has provided a convenient approach for determining conversion coefficients for discrete incidents.
PubDate: 2021-12-01

• A Monte Carlo Dosimetric Parameters of the 60Co High Dose Rate
Brachytherapy and Investigation of TG43 Dose Accuracy in Different Media
Using GATE v8.2 Code

Abstract: The determination of the dose distribution is the key step for accurate dose delivery in brachytherapy as well as radiotherapy application. This research study contributes on the characterization of the 60Co high dose rate brachytherapy source model Co0.A86. We followed the recommendations of the American Association of Physicists in Medicine (AAPM) and European Society for Radiotherapy and Oncology (ESTRO) on dose calculation. In addition, this study aims also to investigate the accuracy of TG-43 algorithms dose calculations in different mediums relevant to high dose rate brachytherapy. For algorithm implementation, we have used the GEANT4 Application for Emission Tomography Monte Carlo code to reach our goal. Furthermore, we compared the obtained results with the previous published results. The obtained dosimetric data sets are in good agreement with the quoted values in the previous studies, where the authors used different Monte Carlo codes.
PubDate: 2021-12-01

• Energy Characteristics of Tsunami Sources and the Mechanism of Wave
Generation by Seismic Movements of the Ocean Floor

Abstract: A physical analysis of the generation of tsunami waves by seismic movements of the ocean floor is presented. For a set of strong underwater earthquakes, the work done against hydrostatic pressure during coseismic displacements of the ocean floor and the available potential energy, tsunami energy, are estimated. It is shown that an insignificant part of the earthquake energy (from 0.004% for Mw = 7 to 0.16 % for Mw = 9) is transferred to the tsunami waves, while the work done against the hydrostatic pressure is comparable in absolute value to the earthquake energy estimated by the Kanamori formula.
PubDate: 2021-12-01

• Searching for EAS Features in the Detection of Delayed Particles and Muons
at the MSU EAS Array

Abstract: Abstract The time distributions of particles in extensive air showers (EASs) have been studied using the EAS array at Moscow State University [1, 2]. More than 105 particles are produced in an EAS during the interaction of cosmic rays with energies above 1014 eV with the atmosphere. Delayed particles are detected in 3.5% of EASs with an unshielded detector located at the Earth’s surface. Muons are detected in 60% of EASs using a shielded detector located under a soil ground layer equivalent to a 20 m of water column. The detector signals are recorded using a two-beam analog storage oscilloscope. It has been found that the detection probability increases when observing muons for EASs containing from $${{10}^{5}}$$ to $${{10}^{6}}$$ particles, and when observing delayed particles for EASs containing from $${{10}^{6}}$$ to $${{10}^{7}}$$ particles. The distribution over distances to the EAS axis when observing delayed particles is wider than for muons and the age distributions do not differ within errors. The features of EASs with delayed particles and the hypothesis that the height of the appearance of delayed particles can be higher than the height at which EAS electrons and muons are produced are considered.
PubDate: 2021-12-01

• A Michelson Space Interferometer with Unequal Arms

Abstract: The principles and technical requirements for using the classical Michelson interferometer as a rangefinder in a constellation of satellites for measuring the parameters of the Earth’s gravitational field are considered.
PubDate: 2021-12-01

• Validation of X-Ray Spectra in Screening Mammography Simulated with Monte
Carlo

Abstract: — Screening mammography is the examination of reference in the fight against breast cancer because of its sensitivity in detecting microlesions. Thus, it is crucial to ensure a good quality examination with the most suitable dose, requirements will depend on the choice of exposure parameters (anode/filter, tube voltage, and current) and the acquisition procedures. To optimize practices, we must understand the relationship between breast dose and image quality. This can be reached by knowing the X-ray energy spectra. This study aims to generate spectra of a mammographic x-ray tube, using two types of targets, Mo and Rh by Monte Carlo simulation using Gate code (GEANT4). To predict the X-ray spectra for the Mo/Mo and Rh/Rh target/filter combinations of the screening mammography tube, Monte Carlo modeling has been carried out using the GATE code (GEANT4); the generated spectra were validated by comparing them with those of the IPEM report 78. The curves of the spectra obtained by the Monte Carlo simulation have been normalized for a reliable comparison. The evaluation of these curves has been performed using statistical analysis with the student’s t-test. The results show that the energy spectra of the GATE code are in agreement with those produced by the IPEM report 78, no statistically significant differences have been observed between the IPEM and simulated spectra (p < 0.05), even though there are slight differences between them, especially in the characteristic intensity of the K-beam and in the low-energy range. Monte Carlo simulation is a reliable method for generating mammography spectra and can be used as a tool for optimizing acquisition parameters.
PubDate: 2021-12-01

• Computed Tomography Scan Optimization of Chest and Abdomen Protocols

Abstract: This work aims to optimize the scanning parameters of Chest and Abdomen protocols in computed tomography, whilst maintaining imagequality and reducing the dose. Two phantoms have been used to evaluate the dose and image quality on a 16-slice HITACHI CT system by establishing the optimization threshold for each protocol. The proposed Thoracic protocol has shown a reduction in Computed Tomography Dose Index (CTDIvol) and Contrast-Noise Ratio (CNR), and the spatial resolution has remained stable with a slight increase in noise. For the optimized Abdominal protocol, CTDIvol has reduced significantly, noise has increased at the two new proposed energies of 100 and 120 kV, and CNR has decreased. This research has shown that by optimizing Chest and Abdomen protocols, substantial dose reductions may be achieved without compromising image quality when using a multi-slice Scanner.
PubDate: 2021-12-01

• LOIS—a Program for Refining the Orbits of Artificial Earth Satellites
Using Global Positioning Systems

Abstract: The LOIS (Low Orbit Improvement Software) program used for high-precision positioning of low-orbit artificial Earth satellites is presented. The differential methods used in the program to refine the orbits are described. The results of refinement of model orbits are presented.
PubDate: 2021-12-01

• The Specific Features of the Surface of Mechanically Renewable Sn- and
Pb-Electrodes in Surface-Inactive Electrolytes

Abstract: The structure of charged phase interfaces between mechanically renewable Sn- and Pb-electrodes and LiClO $$_{4}$$ solutions in acetonitrile (AN) with different concentrations was studied by the impedance method and cyclic voltammetry. The intervals of the potentials at which these electrodes could be considered in good approximation as ideally polarizable were established. The zero-charge potentials were estimated to be $$- 0.37$$ and $$- 0.59$$ V (with respect to aq. SCE) for the Sn- and Pb-electrodes, respectively. The experimental capacitance–potential dependencies were shown to be in good agreement with the classic Gouy–Chapman–Stern–Grahame model. The correlations of the differences between the experimental potentials at zero and strongly negative charges on the electrical double layer with the difference between the vacuum work functions of these metals were considered and analyzed. The results obtained in AN solutions were compared with the data for aqueous solutions of surface-inactive electrolytes. It was shown that these metals should be classified among lyophobic systems similar to mercury and some other mercury-like sp-metals according to the character of their interactions with AN and H $$_{2}$$ O molecules.
PubDate: 2021-12-01

• Validation of GATE Monte Carlo Simulation and Al2O3:C OSL Nanodots for
Entrance Surface Dose Estimation in Mammography

Abstract: In this study, the objective was to give more data related to the use of GATE (Geant4-based Application for Tomographic Emission) and Al2O3:C Optically Stimulated Luminescence (OSL) nanodots, as two alternative methods to estimate entrance surface dose (ESD) in mammography. First, ESD values were simulated with GATE and compared with values measured with Al2O3:C OSL nanodots and Solid State kV/dose Multisensor AGMS-M+ (Radcal,USA), using a standard breast phantom MTM100 (CIRS, USA). On the other hand, GATE simulations were also performed with PMMA slabs of different thicknesses (10 to 90 mm) and then compared with experimental values using AGMS-M+ detector. Results pointed to a maximum difference of 17%, between X-ray spectra simulated with GATE and those calculated with the IPEM report number 78 software, for this reason, the air kerma factor was calculated with GATE and IPEM and compared to the one measured by the AGMS-M+ detector. The ESD results indicate that GATE and Al2O3:C OSL nanodots values were compatible within 4% with those obtained with AGMS-M+. This work gives more data according to the use of GATE and Al2O3:C OSL nanodots to determine the ESD. Indeed, in the literature, there are few studies related to the use of GATE code and Al2O3:C OSL nanodots in mammography systems.
PubDate: 2021-12-01

• Analysis of Radiation Shielding Characteristics of Magnetite/High Density
Polyethylene Nanocomposite at Diagnostic Level Using the MCNPX, XCOM,
XMuDat and Auto-Zeff Programs

Abstract: – Given the lack of data on radiation shielding properties of ironoxide (magnetite) against gamma-rays, this study addresses radiation shielding characteristics of a novel lead-free material, namely magnetite/high density polyethylene (HDPE/Fe3O4) nanocomposite for diagnostic radiology and nuclear medicine purposes.Thus, radiation shielding characteristics of this nanocomposite, including mass attenuation coefficients, half-value layer (HVL) and transmittance (I/I0%) valuesat various concentrationsnamely 0, 1.16, 1.93, 3.87, 5.8, and 7.74 wt % were obtained viathe MCNPX code at low and medium energies. The simulation simulation results exhibited a good agreementwith the other approaches namely XCOM and XMuDat programs. Besides, the effective atomic number was calculated using direct-method and Auto-Zeff software. The results showed that with an increase in the magnetite wt %, the mass attenuation coefficients underwent an increasing trend followed by the effective atomic number.
PubDate: 2021-12-01

• Analysis of Half-Value Layer and Average Glandular Dose for Mammography
Using Gate

Abstract: Absract Background: Screening mammography is an unavoidable method for detecting breast cancer. It is therefore imperative to ensure a quality examination. To optimize practices, it is necessary to control the relationship between the dose to the breast and the image quality, this can be achieved by the Average Glandular Dose (AGD). The objective of this study is to calculate the average absorbed breast dose during a mammography examination by MONTE CARLO simulation using the GATE code (GEANT4). Methods: In this study, we performed our modulation on a digital mammography screening machine. The validation of the modelled simulation configuration was obtained by comparing the modulated spectra with the spectra produced by IPEM SRS 78, and by calculating the HVL values in Al. Finally, the values of the average absorbed dose were studied using the Monte Carlo code GATE, the results were compared with the experimental measurements using a semiconductor detector (Radcal AGMS -DM+) and a MTM100 phantom. Result: Our calculated results for the average glandular dose were consistent with the results of the experimental measurement and the energy spectra produced by GATE were in good agreement with that produced by IPEM Report 78. Conclusion: It can be assumed that the dose received in Mammography is highly dependent on the energy spectrum of the beam. Our modeling for screening mammography using GATE can be applied to further dosimetric studies of the mammography radiation exposure to the breast.
PubDate: 2021-12-01

• Modeling the Dose Distribution in a Bone Implant during Sterilization with
a Fast Electron Flow

Abstract: The passage of fast electron beams with energies in the range from 0.5 to 3 MeV through a fragment of bone tissue during radiation sterilization has been modeled using the GEANT4 software package. Analysis of the data showed that the optimal particle energies are 1 MeV for a sample thickness of 4 mm, 1.5 MeV for a sample thickness of 6 mm, 2 MeV for a sample thickness of 8 mm, and 2.5 MeV for a sample thickness of 10 mm when the sample is irradiated bilaterally or rotated.
PubDate: 2021-12-01

• Uranyl Luminescence Quenching in the Presence of Organic Reagents Based on
2,2'-Bipyridyldicarboxylic Acid

Abstract: The absorption and luminescence spectra and the luminescence decay kinetics of uranyl ions (UO22+) in the presence of organic reagents based on 2,2'-bipyridyldicarboxamides with various substituents have been studied. The quantum yields and luminescence lifetimes of uranyl nitrate hexahydrate and uranyl complexes with organic ligands in acetonitrile solutions have been determined. The mechanism of energy transfer in uranyl complexes is proposed.
PubDate: 2021-12-01

• Monte Carlo Simulation of Surface Dose and Dose Rate in 6MV-FFF Beams

Abstract: — The objective of this study is to demonstrate by Monte Carlo simulation the variation of the surface dose and dose rate for the 6MV-FFF mode compared to the 6MV-FF mode. We demonstrate the effect of the filter on the capture of low energy photons and their impact on the surface dose and dose rate as well as the contribution of the dose induced by the contamination particles. Furthermore, the effect of the heterogeneous medium on the dose rate. The Monte Carlo simulations were validated by experimental measurements in a water phantom using the gamma index (2%/2 mm) and the mean absolute error (MAE). The results obtained indicate that the surface dose is increased in the FFF mode by almost 10% in the 3 $$\times$$ 3, 5 $$\times$$ 5, and 10 $$\times$$ 10 cm2 irradiation fields. The dose rate (Gy/primary particle) is increased for the 6MV-FFF mode by a factor of almost 2.5.
PubDate: 2021-12-01

• Estimation of Computed Tomography Dose Index (CTDI) Using Monte Carlo
Simulation

Abstract: — The use of Monte Carlo methods can help measure radiation doses during a CT procedure to assess radiation risk, such as long-term radiation-induced cancers. Before any Monte Carlo-based simulation can be performed, it must be validated first. This study presents a validation of a Monte Carlo simulation to estimate the computed tomography dose index (CTDI) using a Hitachi Supria 16-slice scanner. This simulation was performed using GATE software which is based on GEANT4 code. CTDI serves to measure the absorbed dose of radiation per rotation of the X-ray tube and is a directly measurable dosimetric parameter. The objective of this study is the validation of a CTDI computed by Monte Carlo simulation with data from experimental measurements for a 16-slice CT system. An ionization chamber and its associated electrometer for phantom measurements. The cylindrical phantom of polymethylmethacrylate (PMMA) with a diameter of 16 cm was used for the determination of the CTDI for 80, 100, and 120 KVp at 100 mAs. The CTDI was measured at the center ( $$CTD{{I}_{c}}$$ ) and at four locations on the periphery ( $$CTD{{I}_{p}}$$ ) of the phantom using the pencil chamber, and then the weighted computed tomography dose index ( $$CTD{{I}_{w}}$$ ) was determined. The measurement data are compared with the results of the GATE simulation. GATE is a simplified platform of the GEANT4 code which is based on Monte Carlo techniques. The differences between CTDI measurements and simulations are 11%, 9%, and 17% for 80, 100, and 120 KVp, respectively. There is a good agreement of $$CTD{{I}_{w}}$$ between simulated and measured results with a deviation of no more than 17%. Thus, the evaluation of $$CTD{{I}_{w}}$$ during a CT protocol can be performed using the configuration adopted in this study.
PubDate: 2021-12-01

• Impact of Aluminum Plates on Uniformity of Depth Dose Distribution in
Object during Electron Processing

Abstract: The impact of aluminum beam modifier plates on the uniformity of the absorbed dose distribution over the depth of objects is studied using computer simulation of the treatment of objects by monoenergetic accelerated electrons with energies from 4 to 10 MeV. It has been found that the method for modifying the electron beam using modifier plates makes it possible to increase the uniformity of the dose distribution over the volume of the treated object by 15–20%.
PubDate: 2021-12-01

• Monte Carlo Simulation as a Predictive Tool to Program a Reloading

Abstract: The purpose of this work is to determine a date for the next reloading operation of the panoramic gamma irradiator of the Moroccan National Institute of Agronomic Research (NIAR) by studying the variation with time of the dosimetric mapping at the inside the irradiation casemate between 2021 and 2030. The NIAR irradiator is a gamma irradiator currently contains 8 cobalt-60 pencils used to develop Moroccan agriculture by doing research in this field by ionization of agricultural products. Monte Carlo simulation via the GEANT4 code was used as a tool to establish the distribution of isodose in the irradiation room due to its important role in meeting the dosimetric requirements for this type of facilities. The results show that from January 1, 2024, serious measures must be taken to arrange a date for the NIAR irradiator reloading operation not later than 2027.
PubDate: 2021-11-01
DOI: 10.3103/S0027134921060047

JournalTOCs
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Email: journaltocs@hw.ac.uk
Tel: +00 44 (0)131 4513762