Accidents involving industrial radiography are the most frequent cause of severe or fatal overexposure to workers and the public. On May 5, 2000, a radiation accident happened at a construction site in a gamma radiogr...Accidents involving industrial radiography are the most frequent cause of severe or fatal overexposure to workers and the public. On May 5, 2000, a radiation accident happened at a construction site in a gamma radiography practice at the village of Meet Halfa-Egypt. The accident was a severe overdose of non-radiation workers due to external exposure of Ir-192. This paper provides a methodology for calculating doses and dose rates from the most commonly used industrial γ-sources: 192Ir, 60Co, 134Cs, 137Cs and 131I. For this purpose, MCNP computer code based on Monte Carlo technique is used. The applied method helps firstly in studying and analyzing the doses from the above mentioned sources. Secondly, it provides a lead container design in a trial to reduce the dose rate within the permissible. Computer models were used to simulate the 192Ir Meet Halfa accident. To verify these models, the calculated doses were compared with a well-known empirical formula to convert source activity into dose rate and then the models were applied at different distances to analyze the factors that affect the deposited dose in the human body to find out the dose received by the victims.展开更多
Objective: The current research study aims to calculate entrance surface air kerma for skull, chest, cervical spine, lumbar spine, and pelvic X-ray examinations in interior posterior and posterior interior positions a...Objective: The current research study aims to calculate entrance surface air kerma for skull, chest, cervical spine, lumbar spine, and pelvic X-ray examinations in interior posterior and posterior interior positions and generate a method for chest dose reduction to decrease radiation risk. Materials and Methods: The indirect dose measurement was used in the current research. The X-ray tube output was measured using RAD-CHECK Plus ionization chamber and the indirect entrance surface air kerma was calculated via applying physical acquisition parameters such as a focus on skin distance, tube current times exposure time (mAs), and applied tube voltage (kV), and applying a mathematical model. Results: The main findings were obtained from comparing the radiation doses with the reference levels of International organizations such as the American College of Radiology and the International Atomic Energy Authority. The mean entrance skin dose for the skull (AP), skull (PA), skull (LAT), cervical spine (PA), cervical spine (LAT), lumbar spine (AP), lumbar spine (LAT), pelvis (AP), and pelvis (LAT) of adult X-ray examinations was within the diagnostic reference dose level values obtained by ACR (2018) except for the ESD for chest (AP) which was 0.88 mGy. Conclusions: The results of the study concluded that by adjusting the applied tube voltage, kV, and tube current product time, mAs decreased the radiation dose to the chest X-ray by 58%.展开更多
An adhesive of the SiBCN ceramic was synthesized through the polymer derived ceramics(PDC)route.Meanwhile with higher adhesion strength and simpler process condition,the polyborosilazane(PSNB)was modified by E-44 epox...An adhesive of the SiBCN ceramic was synthesized through the polymer derived ceramics(PDC)route.Meanwhile with higher adhesion strength and simpler process condition,the polyborosilazane(PSNB)was modified by E-44 epoxy resin.The E-44 epoxy resin was used to promote the oxidation process of SiBCN,in other words,to produce more amount of SiO2-B2O3 glasses.The phase composition,elemental analysis,chemical bonds and microstructure were investigated by using X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),and scanning electron microscope(SEM)measurements.The E-44 modified adhesives were cured at 120℃in air for 2 h,and were pyrolyzed at 1200,1400,and 1500℃for 2 h in air,respectively.The highest adhesion strength of the modified adhesive was up to 5.33,12.23,and 12.50 MPa after being heat treated at 1200,1400,and 1500℃,respectively.Finally,we proposed an adhesion model and revealed the adhesion mechanism of SiBCN ceramic.展开更多
A systematic approach to the design of the conducted electromagnetic interference （EMI） filter of high-density plasma cutting power supply has been developed. Converter components have been accurately modeled, with ...A systematic approach to the design of the conducted electromagnetic interference （EMI） filter of high-density plasma cutting power supply has been developed. Converter components have been accurately modeled, with parasitic elements extracted to reveal their impacts on the EMI noises. Circuit simulations have been used to analyze and minimize the EMI noises. Conducted EMI noise measurement and filter design of this power supply have been achieved which successfully satisfy the FCC class B limits in the frequency range from 150 kHz to 30 MHz. The analyses and experimental results show that the designed filter guarantees that the required attenuation will be achieved.展开更多
The present work examines the validity of using barium as a carrier for radium-226 determination and optimizes the amount added during the radiochemical separation from rock samples. The activity concentration of Ra-2...The present work examines the validity of using barium as a carrier for radium-226 determination and optimizes the amount added during the radiochemical separation from rock samples. The activity concentration of Ra-226 is determined in rock samples by liquid scintillation spectrometer via its short-lived daughters after the radiochemical separation. The activity of Ra-226 was calculated based on the counts measured in a window set for Po-214 peak. The activity measured by Liquid Scintillation Counter, LSC using Pulse Shape Analysis, PSA. Ba-133 was used for chemical yield. The applied method was tested using a Certified Reference Material, CRM ore number-Dl-1a which shows a good agreement with the certified values. The applied method for measuring Ra-226 has been adapted to be used in rocks such as monazite. The average activity for Ra-226 in rock samples collected from the commercial grade Egyptian monazite was 13.85 ± 2.05 Bq/g with a detection limit 9.58 mBq/g. The optimum conditions have been established during the present work such as precision, cost and time preparation which makes the method useful for radio chemists and the decision makers.展开更多
The aim of this study was to measure concentrations and distributions of natural radionuclides occurring in rocks. The activity concentrations (Bq·kg-1) of the naturally occurring radionuclides 226Ra, 232Th, and ...The aim of this study was to measure concentrations and distributions of natural radionuclides occurring in rocks. The activity concentrations (Bq·kg-1) of the naturally occurring radionuclides 226Ra, 232Th, and 40K in sedi- mentary rock samples from Eastern Desert (Um El-Huetat), Nile Valley (Gebel Owina) and from southwest Sinai (Wadi Ghweiba) were measured using a high-purity germanium detector. The samples under investigation (clay, shale and sandstone) were used as raw materials in the construction industry (bricks, ceramics, cement, fillers, etc.). Though the sediments of Egypt have already been investigated in the geological and mineralogical aspects, it is necessary to investigate the natural radioactivity in order to complete their classification. The average concentration values of 226Ra, 232Th, 40K in the surveyed samples were 47 ± 7 , 21± 5, 393±19 Bq.kg-1 (clay); 23 ± 5, 30 ± 6, 563 ± 24 Bq.kg-1 (shale); and 17 ± 4, 14 ± 4, 299 ± 17 Bq.kg-1 (sandstone), respectively. All sediment samples have radium equivalent activities ranging from 55 to 115 Bq·kg-1, lower than the limit set in the OECD Report (370 Bq·kg-1). The overall mean outdoor terrestrial gamma dose rates fluctuate from 28 to 55 nGy·h-1. The external gamma radiation dose due to natural radionuclides present in the samples have been computed and compared with the global averages. In terms of the radiation safety, the natural radioactivity of the sediment in Egypt is below the recommended limits of the gamma dose rate. Therefore, they can be used for all kinds of public buildings.展开更多
In robot-assisted surgery projects,researchers should be able to make fast 3D reconstruction. Usually 2D images acquired with common diagnostic equipments such as UT, CT and MRI are not enough and complete for an accu...In robot-assisted surgery projects,researchers should be able to make fast 3D reconstruction. Usually 2D images acquired with common diagnostic equipments such as UT, CT and MRI are not enough and complete for an accurate 3D reconstruction. There are some interpolation methods for approximating non value voxels which consume large execution time. A novel algorithm is introduced based on generalized regression neural network (GRNN) which can interpolate unknown voxles fast and reliable. The GRNN interpolation is used to produce new 2D images between each two succeeding ultrasonic images. It is shown that the composition of GRNN with image distance transformation can produce higher quality 3D shapes. The results of this method are compared with other interpolation methods practically. It shows this method can decrease overall time consumption on online 3D reconstruction.展开更多
The present work is a comprehensive of drinking water quality. Eleven groundwater samples were taken from various rural regions of Egypt, the groundwater samples were investigated for chemical, radiometric and heavy m...The present work is a comprehensive of drinking water quality. Eleven groundwater samples were taken from various rural regions of Egypt, the groundwater samples were investigated for chemical, radiometric and heavy metals analyses, the major cations including;sodium ( ), potassium ( ), calcium ( ) and magnesium ( ) ions species, the major anions of chloride ( ), sulphate ( ), nitrite ( ), phosphate ( ). Radiometric analyses in water expressed as the gross alpha and beta activity concentrations, heavy metals analyses including arsenic ( ), lead ( ), cobalt ( ), manganese ( ), iron ( ) and cadmium ( ) ions. The groundwater samples were found to contain high concentrations of heavy metals than the limited values of the world health organization (WHO). Heavy metals speciation were performed using MinteqA2 geochemical code. A modified exchange resin was prepared by polymerization of the condensed dioxalayl p-sulphanilamide with phenol, this ion exchange resin was examined by the different techniques such as;x-ray diffraction, infra red spectra (IR), and electronic microscopic, it was found a good adsorbent material that used for the reduction of heavy metals from contaminated groundwater samples.展开更多
<strong>Aim:</strong> To compare and analyze dose constraints and target coverage results and to reduce Bladder Wall (B<sub>wall</sub>) V<sub>18.12</sub> for prostate Stereotactic-B...<strong>Aim:</strong> To compare and analyze dose constraints and target coverage results and to reduce Bladder Wall (B<sub>wall</sub>) V<sub>18.12</sub> for prostate Stereotactic-Body Radiation Therapy (SBRT) when Seminal Vesicles (SSVV) are included or not. Several indicators based on intersection volumes are obtained to predict constraint fulfillment. <strong>Background:</strong> Due to prostate’s low alpha-beta ratio and the possibility of increasing the therapeutic ratio several moderate and extreme hypofractionation schemes have been proposed. The scheme selected was a fivefraction urethra-sparing prostate SBRT. <strong>Materials and Methods:</strong> 150 patients divided into two groups according to the inclusion of SSVV in PTV or not were analyzed. Histograms, average values, standard deviations and degrees of fulfillment were obtained for each constraint or goal and group. A possible reduction of the B<sub>wall</sub> V<sub>18.12</sub> was addressed by re-optimizing fifty randomly chosen patients. Predictors of constraint fulfilling were obtained by using the intersections of B<sub>wall</sub> and Rectum Wall (R<sub>wall</sub>) with the PTV. <strong>Results:</strong> Significant differences in R<sub>wall</sub> V<sub>32.62</sub> and V<sub>29</sub> were obtained when evaluating the influence of SSVV inclusion. A reduction of 12% in the B<sub>wall</sub> V<sub>18.12</sub> constraint was achieved without compromising coverage and OARs doses. No dependence on the inclusion of SSVV was found. <strong>Conclusions:</strong> Statistically significant differences have been found in R<sub>wall</sub> intermediate-dose constraint when SSVV was included. A reduction of 12% in the B<sub>wall</sub> V<sub>18.12</sub> constraint has been achieved without compromising the PTV coverage and the rest of OARs constraints. Constraint fulfillment predictors could be useful to evaluate the feasibility of prostate SBRT prior to the planning process for every single patient.展开更多
The streambed sediments of the Suez Canal have been analyzed for determining the natural radionuclides and long-lived radionuclides such as uranium by gamma and alpha spectrometric techniques. The specific activities ...The streambed sediments of the Suez Canal have been analyzed for determining the natural radionuclides and long-lived radionuclides such as uranium by gamma and alpha spectrometric techniques. The specific activities of 238U series, 232Th series and 40K (Bq/kg) were measured by gamma spectrometry based on Hyper-Pure Germanium detector (HPGe). The average specific activities of 226Ra(238U) series, 232Th series and 40K were ranged from 3.04 ± 1.10 to 14.70 ± 1.24 Bq/kg, from 1.12 ± 0.66 to 16.10 ± 1.30 and from 77 ± 4.90 to 350.50 ± 8.90 Bq/kg respectively. The concentration of 238U and 234U in the streambed sediments are ranged from 3.24 ± 0.21 to 13.34 ± 0.61 ppm and from 3.18 ± 0.02 to 13.77 ± 0.03 ppm in dry weight respectively. 234U/238U ratios of the sediments are relatively lower than unity in many locations indicating the preferential uranium leaching process. The results with the high ratios for 234U/238U were observed in the sediment collected from Port Said. This may be attributed to the sorption of uranium by sediment which has a relatively high content of organic matter. The geochemical behavior of sediment, the chemistry of uranium and the flow rates of water are considered as the most important factors controlling uranium isotopic composition of the streambed sediment. The result of radioactivity in sediment samples can be used to distinguish any future changes due to non-nuclear industries on the Suez Canal area.展开更多
In this work the radiological dose and risks resulting from recycling of radioactive contaminated NORM scrap metal that produced from one of oil and gas production companies in Egypt, were determined by using RESRAD-R...In this work the radiological dose and risks resulting from recycling of radioactive contaminated NORM scrap metal that produced from one of oil and gas production companies in Egypt, were determined by using RESRAD-RECYCLE computer code. Two scenarios were used: the first was the workers’ scenario, while the second was end-use product scenario. Workers’ scenario was used in this study for evaluating the dose and risk to workers who process recycled materials. This scenario focused on the transport of radioactive NORM scrap metal from the place of origin to the smelter (scrap delivery step). Scenarios for six different workers were included under the scrap delivery step: two workers scrap cutter, two workers scrap loader, and two workers scrap truck driver. The values for each scenario were specified on the basis of processing 200 tons of NORM scrap metal. Because these operations occur before melting of the metal, mass and radionuclide partitioning factors were not applied in the scrap metal delivery step. The radionuclide concentration of the NORM scrap metal was used directly in the dose calculation. The maximum doses received from direct external exposure to all radio nuclides during cutter/sorter, scrap truck driver and unloading of scrap metals were 2.14E-04, 1.4E-06 and 1.86E-05 (mSv) respectively. The excess cancer risks for all radio nuclides during cutter/sorter of scrap metals reached 1.25E-07. Radiation exposures incurred by the scrap unloaders and scrap cutters/sorters were greater than those incurred by the other workers for their closer exposure distances and longer time.展开更多
Low-cost adsorbents, Magnesium ferrite (MgFe2O4) nanoparticles were synthesized using three different types of fuel such as Urea, Oxalic acid, and Citric acid via sol-gel auto-combustion method. The prepared products ...Low-cost adsorbents, Magnesium ferrite (MgFe2O4) nanoparticles were synthesized using three different types of fuel such as Urea, Oxalic acid, and Citric acid via sol-gel auto-combustion method. The prepared products were characterized by means of powder X-Ray Diffraction (XRD), Fourier Transform Infrared spectroscopy (FT-IR) and Field Emission Scanning Electron Microscope (FE-SEM). The influence of the fuel used on the morphology and the crystallite size of MgFe2O4 Nano products were studied. The results showed that Citric acid fuel produced pure MgFe2O4 with the smallest crystallite size average cluster = 13.53 nm. The synthesized sample was used for the removal of 99TcO4- anions from low level liquid waste under studied conditions. The different parameters affecting on the adsorption process using the batch method were studied. The results revealed that MgFe2O4 nanostructure has high removal ability of 99TcO4- from aqueous solutions (98.84%). The adsorption data are in good agreement with Freundlich and Pseudo second order isotherm models. The adsorption process was a chemisorption reaction additionally, the results of the thermodynamic parameters indicated that the adsorption of 99TcO4- on nanostructures was an exothermic and spontaneous process.展开更多
文摘Accidents involving industrial radiography are the most frequent cause of severe or fatal overexposure to workers and the public. On May 5, 2000, a radiation accident happened at a construction site in a gamma radiography practice at the village of Meet Halfa-Egypt. The accident was a severe overdose of non-radiation workers due to external exposure of Ir-192. This paper provides a methodology for calculating doses and dose rates from the most commonly used industrial γ-sources: 192Ir, 60Co, 134Cs, 137Cs and 131I. For this purpose, MCNP computer code based on Monte Carlo technique is used. The applied method helps firstly in studying and analyzing the doses from the above mentioned sources. Secondly, it provides a lead container design in a trial to reduce the dose rate within the permissible. Computer models were used to simulate the 192Ir Meet Halfa accident. To verify these models, the calculated doses were compared with a well-known empirical formula to convert source activity into dose rate and then the models were applied at different distances to analyze the factors that affect the deposited dose in the human body to find out the dose received by the victims.
文摘Objective: The current research study aims to calculate entrance surface air kerma for skull, chest, cervical spine, lumbar spine, and pelvic X-ray examinations in interior posterior and posterior interior positions and generate a method for chest dose reduction to decrease radiation risk. Materials and Methods: The indirect dose measurement was used in the current research. The X-ray tube output was measured using RAD-CHECK Plus ionization chamber and the indirect entrance surface air kerma was calculated via applying physical acquisition parameters such as a focus on skin distance, tube current times exposure time (mAs), and applied tube voltage (kV), and applying a mathematical model. Results: The main findings were obtained from comparing the radiation doses with the reference levels of International organizations such as the American College of Radiology and the International Atomic Energy Authority. The mean entrance skin dose for the skull (AP), skull (PA), skull (LAT), cervical spine (PA), cervical spine (LAT), lumbar spine (AP), lumbar spine (LAT), pelvis (AP), and pelvis (LAT) of adult X-ray examinations was within the diagnostic reference dose level values obtained by ACR (2018) except for the ESD for chest (AP) which was 0.88 mGy. Conclusions: The results of the study concluded that by adjusting the applied tube voltage, kV, and tube current product time, mAs decreased the radiation dose to the chest X-ray by 58%.
基金Funded by the Research Fund of the National Key Research and Development Program of China(No.2017YFB0703200)the State Key Laboratory of Solidification Processing(NWPU),China(No.135-QP-2015)the Fundamental Research Funds for the Central Universities(No.3102017zy058).
文摘An adhesive of the SiBCN ceramic was synthesized through the polymer derived ceramics(PDC)route.Meanwhile with higher adhesion strength and simpler process condition,the polyborosilazane(PSNB)was modified by E-44 epoxy resin.The E-44 epoxy resin was used to promote the oxidation process of SiBCN,in other words,to produce more amount of SiO2-B2O3 glasses.The phase composition,elemental analysis,chemical bonds and microstructure were investigated by using X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),and scanning electron microscope(SEM)measurements.The E-44 modified adhesives were cured at 120℃in air for 2 h,and were pyrolyzed at 1200,1400,and 1500℃for 2 h in air,respectively.The highest adhesion strength of the modified adhesive was up to 5.33,12.23,and 12.50 MPa after being heat treated at 1200,1400,and 1500℃,respectively.Finally,we proposed an adhesion model and revealed the adhesion mechanism of SiBCN ceramic.
基金National Natural Science Foundation of China (No. 50477009)
文摘A systematic approach to the design of the conducted electromagnetic interference （EMI） filter of high-density plasma cutting power supply has been developed. Converter components have been accurately modeled, with parasitic elements extracted to reveal their impacts on the EMI noises. Circuit simulations have been used to analyze and minimize the EMI noises. Conducted EMI noise measurement and filter design of this power supply have been achieved which successfully satisfy the FCC class B limits in the frequency range from 150 kHz to 30 MHz. The analyses and experimental results show that the designed filter guarantees that the required attenuation will be achieved.
文摘The present work examines the validity of using barium as a carrier for radium-226 determination and optimizes the amount added during the radiochemical separation from rock samples. The activity concentration of Ra-226 is determined in rock samples by liquid scintillation spectrometer via its short-lived daughters after the radiochemical separation. The activity of Ra-226 was calculated based on the counts measured in a window set for Po-214 peak. The activity measured by Liquid Scintillation Counter, LSC using Pulse Shape Analysis, PSA. Ba-133 was used for chemical yield. The applied method was tested using a Certified Reference Material, CRM ore number-Dl-1a which shows a good agreement with the certified values. The applied method for measuring Ra-226 has been adapted to be used in rocks such as monazite. The average activity for Ra-226 in rock samples collected from the commercial grade Egyptian monazite was 13.85 ± 2.05 Bq/g with a detection limit 9.58 mBq/g. The optimum conditions have been established during the present work such as precision, cost and time preparation which makes the method useful for radio chemists and the decision makers.
文摘The aim of this study was to measure concentrations and distributions of natural radionuclides occurring in rocks. The activity concentrations (Bq·kg-1) of the naturally occurring radionuclides 226Ra, 232Th, and 40K in sedi- mentary rock samples from Eastern Desert (Um El-Huetat), Nile Valley (Gebel Owina) and from southwest Sinai (Wadi Ghweiba) were measured using a high-purity germanium detector. The samples under investigation (clay, shale and sandstone) were used as raw materials in the construction industry (bricks, ceramics, cement, fillers, etc.). Though the sediments of Egypt have already been investigated in the geological and mineralogical aspects, it is necessary to investigate the natural radioactivity in order to complete their classification. The average concentration values of 226Ra, 232Th, 40K in the surveyed samples were 47 ± 7 , 21± 5, 393±19 Bq.kg-1 (clay); 23 ± 5, 30 ± 6, 563 ± 24 Bq.kg-1 (shale); and 17 ± 4, 14 ± 4, 299 ± 17 Bq.kg-1 (sandstone), respectively. All sediment samples have radium equivalent activities ranging from 55 to 115 Bq·kg-1, lower than the limit set in the OECD Report (370 Bq·kg-1). The overall mean outdoor terrestrial gamma dose rates fluctuate from 28 to 55 nGy·h-1. The external gamma radiation dose due to natural radionuclides present in the samples have been computed and compared with the global averages. In terms of the radiation safety, the natural radioactivity of the sediment in Egypt is below the recommended limits of the gamma dose rate. Therefore, they can be used for all kinds of public buildings.
文摘In robot-assisted surgery projects,researchers should be able to make fast 3D reconstruction. Usually 2D images acquired with common diagnostic equipments such as UT, CT and MRI are not enough and complete for an accurate 3D reconstruction. There are some interpolation methods for approximating non value voxels which consume large execution time. A novel algorithm is introduced based on generalized regression neural network (GRNN) which can interpolate unknown voxles fast and reliable. The GRNN interpolation is used to produce new 2D images between each two succeeding ultrasonic images. It is shown that the composition of GRNN with image distance transformation can produce higher quality 3D shapes. The results of this method are compared with other interpolation methods practically. It shows this method can decrease overall time consumption on online 3D reconstruction.
文摘The present work is a comprehensive of drinking water quality. Eleven groundwater samples were taken from various rural regions of Egypt, the groundwater samples were investigated for chemical, radiometric and heavy metals analyses, the major cations including;sodium ( ), potassium ( ), calcium ( ) and magnesium ( ) ions species, the major anions of chloride ( ), sulphate ( ), nitrite ( ), phosphate ( ). Radiometric analyses in water expressed as the gross alpha and beta activity concentrations, heavy metals analyses including arsenic ( ), lead ( ), cobalt ( ), manganese ( ), iron ( ) and cadmium ( ) ions. The groundwater samples were found to contain high concentrations of heavy metals than the limited values of the world health organization (WHO). Heavy metals speciation were performed using MinteqA2 geochemical code. A modified exchange resin was prepared by polymerization of the condensed dioxalayl p-sulphanilamide with phenol, this ion exchange resin was examined by the different techniques such as;x-ray diffraction, infra red spectra (IR), and electronic microscopic, it was found a good adsorbent material that used for the reduction of heavy metals from contaminated groundwater samples.
文摘<strong>Aim:</strong> To compare and analyze dose constraints and target coverage results and to reduce Bladder Wall (B<sub>wall</sub>) V<sub>18.12</sub> for prostate Stereotactic-Body Radiation Therapy (SBRT) when Seminal Vesicles (SSVV) are included or not. Several indicators based on intersection volumes are obtained to predict constraint fulfillment. <strong>Background:</strong> Due to prostate’s low alpha-beta ratio and the possibility of increasing the therapeutic ratio several moderate and extreme hypofractionation schemes have been proposed. The scheme selected was a fivefraction urethra-sparing prostate SBRT. <strong>Materials and Methods:</strong> 150 patients divided into two groups according to the inclusion of SSVV in PTV or not were analyzed. Histograms, average values, standard deviations and degrees of fulfillment were obtained for each constraint or goal and group. A possible reduction of the B<sub>wall</sub> V<sub>18.12</sub> was addressed by re-optimizing fifty randomly chosen patients. Predictors of constraint fulfilling were obtained by using the intersections of B<sub>wall</sub> and Rectum Wall (R<sub>wall</sub>) with the PTV. <strong>Results:</strong> Significant differences in R<sub>wall</sub> V<sub>32.62</sub> and V<sub>29</sub> were obtained when evaluating the influence of SSVV inclusion. A reduction of 12% in the B<sub>wall</sub> V<sub>18.12</sub> constraint was achieved without compromising coverage and OARs doses. No dependence on the inclusion of SSVV was found. <strong>Conclusions:</strong> Statistically significant differences have been found in R<sub>wall</sub> intermediate-dose constraint when SSVV was included. A reduction of 12% in the B<sub>wall</sub> V<sub>18.12</sub> constraint has been achieved without compromising the PTV coverage and the rest of OARs constraints. Constraint fulfillment predictors could be useful to evaluate the feasibility of prostate SBRT prior to the planning process for every single patient.
文摘The streambed sediments of the Suez Canal have been analyzed for determining the natural radionuclides and long-lived radionuclides such as uranium by gamma and alpha spectrometric techniques. The specific activities of 238U series, 232Th series and 40K (Bq/kg) were measured by gamma spectrometry based on Hyper-Pure Germanium detector (HPGe). The average specific activities of 226Ra(238U) series, 232Th series and 40K were ranged from 3.04 ± 1.10 to 14.70 ± 1.24 Bq/kg, from 1.12 ± 0.66 to 16.10 ± 1.30 and from 77 ± 4.90 to 350.50 ± 8.90 Bq/kg respectively. The concentration of 238U and 234U in the streambed sediments are ranged from 3.24 ± 0.21 to 13.34 ± 0.61 ppm and from 3.18 ± 0.02 to 13.77 ± 0.03 ppm in dry weight respectively. 234U/238U ratios of the sediments are relatively lower than unity in many locations indicating the preferential uranium leaching process. The results with the high ratios for 234U/238U were observed in the sediment collected from Port Said. This may be attributed to the sorption of uranium by sediment which has a relatively high content of organic matter. The geochemical behavior of sediment, the chemistry of uranium and the flow rates of water are considered as the most important factors controlling uranium isotopic composition of the streambed sediment. The result of radioactivity in sediment samples can be used to distinguish any future changes due to non-nuclear industries on the Suez Canal area.
文摘In this work the radiological dose and risks resulting from recycling of radioactive contaminated NORM scrap metal that produced from one of oil and gas production companies in Egypt, were determined by using RESRAD-RECYCLE computer code. Two scenarios were used: the first was the workers’ scenario, while the second was end-use product scenario. Workers’ scenario was used in this study for evaluating the dose and risk to workers who process recycled materials. This scenario focused on the transport of radioactive NORM scrap metal from the place of origin to the smelter (scrap delivery step). Scenarios for six different workers were included under the scrap delivery step: two workers scrap cutter, two workers scrap loader, and two workers scrap truck driver. The values for each scenario were specified on the basis of processing 200 tons of NORM scrap metal. Because these operations occur before melting of the metal, mass and radionuclide partitioning factors were not applied in the scrap metal delivery step. The radionuclide concentration of the NORM scrap metal was used directly in the dose calculation. The maximum doses received from direct external exposure to all radio nuclides during cutter/sorter, scrap truck driver and unloading of scrap metals were 2.14E-04, 1.4E-06 and 1.86E-05 (mSv) respectively. The excess cancer risks for all radio nuclides during cutter/sorter of scrap metals reached 1.25E-07. Radiation exposures incurred by the scrap unloaders and scrap cutters/sorters were greater than those incurred by the other workers for their closer exposure distances and longer time.
文摘Low-cost adsorbents, Magnesium ferrite (MgFe2O4) nanoparticles were synthesized using three different types of fuel such as Urea, Oxalic acid, and Citric acid via sol-gel auto-combustion method. The prepared products were characterized by means of powder X-Ray Diffraction (XRD), Fourier Transform Infrared spectroscopy (FT-IR) and Field Emission Scanning Electron Microscope (FE-SEM). The influence of the fuel used on the morphology and the crystallite size of MgFe2O4 Nano products were studied. The results showed that Citric acid fuel produced pure MgFe2O4 with the smallest crystallite size average cluster = 13.53 nm. The synthesized sample was used for the removal of 99TcO4- anions from low level liquid waste under studied conditions. The different parameters affecting on the adsorption process using the batch method were studied. The results revealed that MgFe2O4 nanostructure has high removal ability of 99TcO4- from aqueous solutions (98.84%). The adsorption data are in good agreement with Freundlich and Pseudo second order isotherm models. The adsorption process was a chemisorption reaction additionally, the results of the thermodynamic parameters indicated that the adsorption of 99TcO4- on nanostructures was an exothermic and spontaneous process.
