The Experts below are selected from a list of 222 Experts worldwide ranked by ideXlab platform
Rikuo Machinami - One of the best experts on this subject based on the ideXlab platform.
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revised organ partition of Thorium 232 in thorotrast patients
Radiation Research, 1999Co-Authors: Yuichi Ishikawa, James A H Humphreys, Clare G Collier, N D Priest, Y Kato, Takesaburo Mori, Rikuo MachinamiAbstract:Risk estimates for internally deposited α particles in humans, such as those for α-particle-induced leukemia, have been derived from data on the toxicity of 232 Th in patients injected with Thorotrast. Their derivation requires both epidemiological data and organ doses calculated from the volume of Thorotrast injected and a knowledge of its pattern of deposition within the body. However, accumulating evidence suggests that the organ partition of 232 Th that has commonly been used for dosimetry (i.e. liver:spleen:red bone marrow: others tissues = 59:29:9:3) is inaccurate. In the present study, the organ distribution of 232 Th has been recalculated using a revised averaging method and both published data and our own unpublished data. For the three major organs of deposition (liver, spleen and bone marrow), activity concentration data were selected from 27 published papers and data sets including 140 newly compiled Japanese cases. For organs of minor storage, both published data for 38 German and 24 Japanese autopsy cases and new data were used. The revised estimate of the relative partition of 232 Th among the above organs was 53:14:25:8. It follows that doses calculated to date are essentially correct for the liver but are too high for the spleen and about three times too low for the red bone marrow. This suggests that the risk of α-particle-induced leukemia, per unit of α-particle dose, in Thorotrast patients is about three times lower than previously thought.
Yuichi Ishikawa - One of the best experts on this subject based on the ideXlab platform.
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revised organ partition of Thorium 232 in thorotrast patients
Radiation Research, 1999Co-Authors: Yuichi Ishikawa, James A H Humphreys, Clare G Collier, N D Priest, Y Kato, Takesaburo Mori, Rikuo MachinamiAbstract:Risk estimates for internally deposited α particles in humans, such as those for α-particle-induced leukemia, have been derived from data on the toxicity of 232 Th in patients injected with Thorotrast. Their derivation requires both epidemiological data and organ doses calculated from the volume of Thorotrast injected and a knowledge of its pattern of deposition within the body. However, accumulating evidence suggests that the organ partition of 232 Th that has commonly been used for dosimetry (i.e. liver:spleen:red bone marrow: others tissues = 59:29:9:3) is inaccurate. In the present study, the organ distribution of 232 Th has been recalculated using a revised averaging method and both published data and our own unpublished data. For the three major organs of deposition (liver, spleen and bone marrow), activity concentration data were selected from 27 published papers and data sets including 140 newly compiled Japanese cases. For organs of minor storage, both published data for 38 German and 24 Japanese autopsy cases and new data were used. The revised estimate of the relative partition of 232 Th among the above organs was 53:14:25:8. It follows that doses calculated to date are essentially correct for the liver but are too high for the spleen and about three times too low for the red bone marrow. This suggests that the risk of α-particle-induced leukemia, per unit of α-particle dose, in Thorotrast patients is about three times lower than previously thought.
M A Misdaq - One of the best experts on this subject based on the ideXlab platform.
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Study of pollution in the El Jadida-Safi Atlantic coastal zone (Morocco) by using PIXE and SSNTD methods.
Journal of Environmental Radioactivity, 2008Co-Authors: H. Erramli, M A Misdaq, H.d. Gogon, Thierry Sauvage, Claire RambozAbstract:Abstract In this work, PIXE experiments were performed for measuring heavy and light elements' (ranging from aluminium to lead) concentrations inside various polluted and unpolluted soils as well as liquid samples collected from different phosphate factory sewers in the El Jadida-Safi Atlantic coastal region (Morocco). In addition, uranium ( 238 U) and Thorium ( 232 Th) contents were evaluated in the same samples studied by using CR-39 and LR-115 type II solid state nuclear track detectors (SSNTDs). The influence of the phosphate industry wastes on the concentrations of both radioactive and non-radioactive elements of the samples studied was investigated.
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analysis of radon uranium 238 and Thorium 232 in potable waters dose to adult members of the moroccan urban population
Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 2007Co-Authors: M A Misdaq, H Ouabi, A MerzoukiAbstract:Abstract Uranium ( 238 U) and Thorium ( 232 Th) concentrations as well as radon ( 222 Rn) and thoron ( 220 Rn) alpha-activities per unit volume have been measured inside various potable water samples collected from nineteen cities in Morocco by using CR-39 and LR-115 type II solid state nuclear track detectors (SSNTDs). Measured radon alpha-activities ranged from (0.37 ± 0.02) Bq l −1 to (13.6 ± 1.10) Bq l −1 for the potable water samples studied. Alpha-activities due to radon from the ingestion of the studied potable water samples were determined in different compartments of the gastrointestinal system by using the ICRP compartmental model for radon. Annual committed equivalent doses due to radon were evaluated in the gastrointestinal compartments from the ingestion of the potable water samples studied. The influence of the target tissue mass, radon intake and alpha-activity integral due to radon on the annual committed equivalent doses in the gastrointestinal compartments was investigated.
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Study of the weekly irrigation cycle of a cultivated field in a semi-arid area (Marrakech region, Morocco) by using CR-39 and LR-115 II track detectors and radon as a natural tracer
Radiation Measurements, 2007Co-Authors: M A Misdaq, Z. EssaouifAbstract:Abstract Uranium ( 238 U) and Thorium ( 232 Th) concentrations were measured in the soil of a cultivated field situated in a semi-arid area (Marrakech, Morocco) by using CR-39 and LR-115 type II solid state nuclear track detectors (SSNTDs). The same track detectors were used for measuring alpha- and beta-activities due to radon and thoron gases emanating from the soil of the studied irrigated agricultural field. The influence of the humidity (soil water content), soil depth and climate conditions on the weekly irrigation cycle of the studied cultivated field was investigated by exploiting radon measurements.
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The Influence of the Calcination and Water Washing Treatments on the Uranium Content in Sedimentary Phosphate Samples Using Solid State Nuclear Track Detectors and Gamma-Ray Spectrometry
Journal of Radioanalytical and Nuclear Chemistry, 2000Co-Authors: M A Misdaq, Y. Ouahidi, S. Fakhi, J. Lamine, A. Bakhchi, A. Yves, M. Azouazi, J. C. Abbe, M. BenmansourAbstract:The uranium and Thorium contents were evaluated in the 100–400 µm granulometric fraction of different sedimentary phosphate samples by using a method based on determining the mean critical angles of etching of the CR-39 and LR-115 type II solid state nuclear track detectors (SSNTD) for detecting α-particles emitted by the nuclei of the uranium-238 and Thorium-232 series. Data obtained were compared with the results of γ-ray spectrometry measurements performed on the same samples. The influence of the calcination and water washing treatments as well as the lithology and stratigraphy on the uranium concentration of the phosphate samples was investigated.
Naz T Jarallah - One of the best experts on this subject based on the ideXlab platform.
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the relationship of nuclear decay methods alpha and beta particles with the nuclear deformation for nuclei inuranium 238 and Thorium 232 series
Energy Procedia, 2019Co-Authors: Huda A Marid, Naz T JarallahAbstract:Abstract In this work, a study of the relationship of the decay mode (alpha and beta) emission and the deformed shape of even-even nuclei in uranium -238 and Thorium -232 series is presented. To achieve our purpose the quadrupole deformation parameter (β2) (which refers to the shape of nuclei) and eccentricity (e) (represented the radioactivity) have been compute for each nuclei which decay by (alpha or beta) particles emission in each series. The results of deformation parameter show that the deformation on the shape of nuclei (near from spherical shape) for nuclei which decay by beta particles emission is lower than the deformation on the shape of the nuclei which decay by alpha particles emission for two series. In addition, we shows that the effected of deformation parameter greeter than the effected of eccentricity by the type of decay (alpha & beta) emission. Finally, an empirical equation has been extracted from plotting deformation parameter as a function to eccentricity, which can be used to calculate the defamation parameter for any nuclei has eccentricity value.
T L Ku - One of the best experts on this subject based on the ideXlab platform.
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distribution of Thorium 232 in manganese nodules and crusts paleoceanographic implications
Paleoceanography, 1990Co-Authors: T L KuAbstract:Detailed depth profiles of 232Th in deep-sea ferromanganese nodules and encrustations often show a subsurface maximum followed by a drastic inward decrease to a certain depth before levelling out. Length scales of this feature vary among the profiles but are proportional to growth rates of the specimens, suggesting that the profiles record changes in oceanic 232Th flux with time. Consideration of the nodule chronology, the history of eolian accumulation recorded in sediment cores, and the marine geochemical behavior and budget of 232Th leads us to propose that 232Th in nodules/crusts is of eolian origin. The drastic inward decrease of 232Th is a reflection of increase in the wind borne dust flux induced by the Northern Hemisphere glaciation beginning 2–3 Ma. The subsurface 232Th peak may indicate the decline of eolian flux since 0.1–0.3 Ma.