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1.
Int J Cancer ; 151(4): 510-517, 2022 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-35429352

RESUMO

We analyzed long-term incidence trends in liver cancer (including hepatocellular carcinoma and intrahepatic cholangiocarcinoma) with an aim to interpret the changes in terms of known risk factors and hypothesize that historical exposure to Thorotrast, a radiographic contrast medium emitting alpha particles, has changed population rates. The NORDCAN database was used to collect cancer registry data from Denmark (DK), Finland (FI), Norway (NO) and Sweden (SE), which we used from 1953 (DK, FI and NO) and 1960 (SE) through 2019. Thorotrast, which caused a 100-fold risk of liver cancer was used in DK and SE, and probably also in FI between 1930 and 1950, but not in NO. The incidence trend for liver cancer showed a broad maximum at around 1980, most prominent and statistically significant in SE and DK men and women, and in all countries, a steadily increasing trend towards the end of follow-up. Incidence for NO was lower than for the other countries and the rates showed no peaking at around 1980. Birth cohort analysis identified a transient risk which could be dated to a period between 1930 and 1950 in countries other than NO. Considering a lag time between Thorotrast use and liver cancer appearance, the large incidence peak around 1980 in DK and DE was probably contributed by Thorotrast but considering the ecological nature of the findings, the association should be considered cautiously as hypothesis generating. The late increase in liver cancer risk is most likely lifestyle related and largely preventable.


Assuntos
Neoplasias dos Ductos Biliares , Carcinoma Hepatocelular , Neoplasias Hepáticas , Dióxido de Tório , Neoplasias dos Ductos Biliares/epidemiologia , Ductos Biliares Intra-Hepáticos , Carcinoma Hepatocelular/induzido quimicamente , Carcinoma Hepatocelular/epidemiologia , Dinamarca/epidemiologia , Feminino , Finlândia/epidemiologia , Humanos , Incidência , Neoplasias Hepáticas/induzido quimicamente , Neoplasias Hepáticas/epidemiologia , Masculino , Noruega/epidemiologia , Suécia/epidemiologia , Dióxido de Tório/efeitos adversos
2.
Z Med Phys ; 32(2): 135-141, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35248451
3.
Int J Cancer ; 151(2): 200-208, 2022 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-35213036

RESUMO

Cancers of the gallbladder and extrahepatic bile ducts (called here "GBC" because gallbladder cancer is the main component) are rare in Europe, including the Nordic countries. Their incidence has varied for unknown reasons and we hypothesize that Thorotrast, a previously used carcinogenic radiographic contrast medium, has contributed to the incidence trends. We obtained incidence and survival data from the NORDCAN database, which includes cancer registry data from Denmark (DK), Finland (FI), Norway (NO) and Sweden (SE), which are globally the oldest national cancer databases, starting from 1943 in DK, 1953 in FI and NO and 1960 in SE, and extending to 2016. The incidence trend for GBC showed a broad maximum around 1980 in men (close to 3/100 000) and women (4/100 000), except for NO, where this phenomenon was not seen. In 1955, FI and NO incidence rates were equal but FI rates peaked and later declined similar to DK and SE rates. By 2010, the incidence was similar in all Nordic countries, for both men and women, at close to 2.0/100 000. Birth cohort analysis showed strong effects for countries other than NO. Relative 1-year survival increased for men from 20% to about 50% and similarly for women although at a 5 percentage points lower level. Survival in NO was better than in other countries in the 1980s. Thorotrast, causing a high risk of GBC, was extensively used in the Nordic countries between 1930 and end of 1940s, with the exception of NO, where these was no documented use. These data suggest that Thorotrast influenced GBC epidemiology and probably worsened survival in certain periods.


Assuntos
Ductos Biliares Extra-Hepáticos , Neoplasias da Vesícula Biliar , Dióxido de Tório , Distribuição por Idade , Dinamarca/epidemiologia , Feminino , Finlândia/epidemiologia , Neoplasias da Vesícula Biliar/epidemiologia , Neoplasias da Vesícula Biliar/etiologia , Humanos , Incidência , Masculino , Noruega/epidemiologia , Sistema de Registros , Suécia/epidemiologia
4.
Environ Pollut ; 281: 116969, 2021 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-33845224

RESUMO

Inhalation represents the most prevalent route of exposure with Thorium-232 compounds (Th-nitrate/Th-dioxide)/Th-containing dust in real occupational scenario. The present study investigated the mechanism of Th response in normal human alveolar epithelial cells (WI26), exposed to Th-nitrate or colloidal Th-dioxide (1-100 µg/ml, 24-72 h). Assessment in terms of changes in cell morphology, cell proliferation (cell count), plasma membrane integrity (lactate dehydrogenase leakage) and mitochondrial metabolic activity (MTT reduction) showed that Th-dioxide was quantitatively more deleterious than Th-nitrate to WI26 cells. TEM and immunofluorescence analysis suggested that Th-dioxide followed a clathrin/caveolin-mediated endocytosis, however, membrane perforation/non-endocytosis seemed to be the mode of Th internalization in cells exposed to Th-nitrate. Th-estimation by ICP-MS showed significantly higher uptake of Th in cells treated with Th-dioxide than with Th-nitrate at a given concentration. Both Th-dioxide and nitrate were found to increase the level of reactive oxygen species, which seemed to be responsible for lipid peroxidation, alteration in mitochondrial membrane potential and DNA-damage. Amongst HSPs, the protein levels of HSP70 and HSP90 were affected differentially by Th-nitrate/dioxide. Specific inhibitors of ATM (KU55933) or HSP90 (17AAG) were found to increase the Th- cytotoxicity suggesting prosurvival role of these signaling molecules in rescuing the cells from Th-toxicity.


Assuntos
Dióxido de Tório , Contagem de Células , Dano ao DNA , Células Epiteliais , Humanos , Pulmão/química , Nitratos/toxicidade , Estresse Oxidativo , Espécies Reativas de Oxigênio , Tório/análise
5.
Aquat Toxicol ; 209: 113-120, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30769157

RESUMO

Thorium (Th) is a natural radioactive element present in the environment and has the potential to be used as a clean nuclear fuel. Relatively little is known about the aquatic toxicity of Th, especially in nanoparticulate form, which may be the main chemical species of Th in the natural waters. In this study, impacts of ThO2 nanoparticles (NPs) with two different sizes (52 ± 5 nm, s-ThO2vs. 141 ± 6 nm, b-ThO2) on a green alga Chlorella pyrenoidosa (C. pyrenoidosa) were evaluated. Results indicated that C. pyrenoidosa was more sensitive to s-ThO2 (96-h EC30 = 64.1 µM) than b-ThO2 (96-h EC30 = 100.2 µM). Exposure to 200 µM of ThO2 NPs reduced the chlorophyll-a and chlorophyll-b contents of the algal cells. At 96 h, SEM and TEM showed that more agglomerates of s-ThO2 than those of b-ThO2 were attached onto the surface of algal cells. Reactive oxygen species (ROS) generation and membrane damage were induced after the attachment of high concentrations of ThO2 NPs. The heteroagglomeration between ThO2 NPs and algal cells and increased oxidative stress might play important roles in the toxicity of ThO2 NPs. To the best of our knowledge, this is the first report on aquatic toxicity of ThO2 NPs.


Assuntos
Chlorella/efeitos dos fármacos , Nanopartículas/toxicidade , Tamanho da Partícula , Dióxido de Tório/toxicidade , Testes de Toxicidade , Permeabilidade da Membrana Celular/efeitos dos fármacos , Chlorella/citologia , Chlorella/crescimento & desenvolvimento , Chlorella/ultraestrutura , Clorofila/análise , Clorofila A/análise , Oxirredução , Estresse Oxidativo/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Poluentes Químicos da Água/toxicidade
6.
Int J Radiat Biol ; 95(10): 1378-1389, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-30676164

RESUMO

Studies of ionizing radiation effects through the archiving of data began with standardizing medical treatments in the early 1900s shortly after the discovery of X-rays. Once the breadth of the delayed effects of ionizing radiation was recognized, the need for long-term follow up became apparent. There are now many human archives of data from nuclear disasters and accidents, occupational exposures, and medical procedures. Planned animal irradiation experiments began around the time of the Cold War and included a variety of doses, fractions, dose rates, and types of ionizing radiation. The goal of most of these studies was to supplement information coming from human data through carefully planned experimental conditions and immediate and uninterrupted data collection. This review aims to highlight major archives and databases that have shaped the field of radiation biology and provide a broad range of the types of datasets currently available. By preserving all of these data and tissue sets, radiation biologists can combine databases and conduct large-scale analyses of detailed existing data and perform new assays with cutting edge scientific approaches.


Assuntos
Bases de Dados Factuais , Lesões por Radiação/epidemiologia , Lesões por Radiação/história , Radiação Ionizante , Radiobiologia , Poluentes Radioativos do Ar , Animais , Acidente Nuclear de Chernobyl , Alemanha , História do Século XX , História do Século XXI , Humanos , Camundongos , Centrais Nucleares , Guerra Nuclear , Exposição Ocupacional , Traumatismos Ocupacionais , Lesões por Radiação/terapia , Poluentes Radioativos do Solo , Dióxido de Tório/efeitos adversos , Estados Unidos
7.
Radiologe ; 56(12): 1072-1078, 2016 Dec.
Artigo em Alemão | MEDLINE | ID: mdl-27885402

RESUMO

Detection of gadolinium deposits in patients who have repeatedly been administered intravenous gadolinium chelates have given rise to concern regarding the long-term safety of magnetic resonance imaging (MRI) contrast media. Nevertheless, negative long-term clinical effects have not yet been observed. In some publications parallels have been drawn to the sequelae of thorotrast that was formerly used for arterial angiography. In this article the history of thorotrast use is briefly described and in particular why, despite warnings, this substance was used frequently and worldwide. A brief summary of the results of the German Thorotrast Study revealed that high excess rates were only observed for primary malignant liver tumors after a 15-year or longer latency period and to a lesser degree of leukemias, as well as for severe local complications due to paravascular injections, particularly in the neck region. Based on this historical review, we will venture to take stock of the outcome from the "success story" of this contrast agent.


Assuntos
Angiografia/história , Doença Hepática Induzida por Substâncias e Drogas/história , Meios de Contraste/história , Neoplasias Hepáticas/história , Radiologia/história , Dióxido de Tório/história , Alemanha , História do Século XX , Humanos
8.
Radiat Environ Biophys ; 55(3): 281-9, 2016 08.
Artigo em Inglês | MEDLINE | ID: mdl-27154786

RESUMO

It is well known that exposures like those from (226)Ra, (224)Ra and Thorotrast(®) injections increase the risk of neoplasia in bone marrow and liver. The thorium-based radioactive contrast agent Thorotrast(®) was introduced in 1929 and applied worldwide until the 1950s, especially in angiography and arteriography. Due to the extremely long half-life of several hundred years and the life-long retention of the thorium dioxide particles in the human body, patients suffer lifetime internal exposure. The health effects from the incorporated thorium were investigated in a few cohort studies with a German study being the largest among them. This retrospective cohort study was set up in 1968 with a follow-up until 2004. The study comprises 2326 Thorotrast patients and 1890 patients of a matched control group. For those being alive at the start of the study in 1968 follow-up was done by clinical examinations on a biannual basis. For the others, causes of death were collected in various ways. Additionally, clinical, radiological and biophysical studies of patients were conducted and large efforts were made to best estimate the radiation doses associated with incorporation of the Thorotrast. The aim of this paper is to describe the cohort, important results and some open questions. The data from the German Thorotrast Study are available to other interested researchers. Information can be found at http://storedb.org .


Assuntos
Carcinógenos/toxicidade , Meios de Contraste/toxicidade , Neoplasias Induzidas por Radiação/epidemiologia , Dióxido de Tório/toxicidade , Estudos de Coortes , Alemanha/epidemiologia , Humanos
9.
Talanta ; 152: 211-8, 2016 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-26992513

RESUMO

Two novel thoria (ThO2) nanoparticles-carbon paste electrodes were used to evaluate an anodic stripping voltammetric method for the direct determination of arsenite and total inorganic arsenic (arsenite plus arsenate) in water samples. The effect of Ag((I)), Cu((II)), Hg((II)), Sb((III)) and Se((IV)) ions on the electrochemical response of arsenic was assayed. The developed electroanalytical method offers a rapid procedure with improved analytical characteristics including good repeatability (3.4%) at low As((III)) concentrations, high selectivity, lower detection limit (0.1 µg L(-1)) and high sensitivity (0.54 µA µg(-1) L). The analytical capability of the optimized method was demonstrated by the determination of arsenic in certified reference materials (trace elements in natural water, trace elements in water and coal fly ash).


Assuntos
Arsênio/isolamento & purificação , Arsenitos/isolamento & purificação , Nanopartículas/química , Dióxido de Tório/química , Poluentes Químicos da Água/isolamento & purificação , Carbono/química , Técnicas Eletroquímicas , Eletrodos , Água Doce/química , Limite de Detecção , Nanocompostos/química , Nanocompostos/ultraestrutura , Nanopartículas/ultraestrutura
10.
Histochem Cell Biol ; 145(1): 41-51, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26608651

RESUMO

Biological material itself appears with poor contrast in electron microscopy (EM), due to its composition mostly of light elements. Classical staining agents such as osmium tetroxide, uranyl acetate, and lead citrate preserve and/or stain cellular structures such as membranes, cytoplasm, and organelles well for EM. However, extracellular polymeric substances (EPS) show no or only poor contrast with these staining agents. The endothelial glycocalyx in blood vessels consists mainly of proteoglycans. It can be visualized by EM only by additional staining with heavy metal ions such as copper (Alcian blue, cupromeronic blue), ruthenium (ruthenium red), or lanthanum. Best results are achieved by combined perfusion of fixative and stain. Cationic hydrous thorium dioxide colloids (named here cThO2) trace acidic groups in EPS. We describe here the use of cThO2 to visualize the glomerular endothelial glycocalyx in the mouse kidney. cThO2 shows high electron density and binds to a continuous layer of up to a few hundred nanometers thickness on the glomerular endothelium, as well as on epithelia in other blood vessels in perfused animals. The observed staining pattern gives rise to periodic densities, with a spacing varying between 50 and 200 nm, depending on the overall layer thickness, which varies between below 50 up to 300 nm. Due to high electron density of the used cThO2 particles, the introduced method allows distinct imaging and precise fine structural analysis of the endothelial glycocalyx.


Assuntos
Tomografia com Microscopia Eletrônica/métodos , Células Endoteliais/citologia , Glicocálix/metabolismo , Glomérulos Renais/citologia , Dióxido de Tório/metabolismo , Animais , Coloides/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Coloração e Rotulagem
12.
Pathol Int ; 64(6): 251-62, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24965107

RESUMO

The effects of radiation on human health have been a major concern, especially after the Fukushima Daiichi Nuclear Power Plant (FNPP) accident. We can determine these effects only from radiological disasters. The radiological contrast medium Thorotrast is known to induce hepatic cancers decades after injection. Using archival materials from Thorotrast patients, we performed molecular pathological studies to elucidate carcinogenic mechanisms of internal radiation exposure. It is emphasized here that radiation-induced cancers are a complex consequence of biological response to radiation and ingested radionuclides. We further expanded the study to establish clinically relevant radioresistant cancer cells in order to develop more effective and less harmful radiation therapy. We also found that cancer cells can acquire radioresistance by low-dose fractionated radiation within one month. The FNPP accidents prompted us to collect tissue samples from animals in and around the evacuation zone in order to construct a tissue bank. The final goal of the bank is to enable research that will contribute to the common understanding of radioprotection.


Assuntos
Neoplasias Induzidas por Radiação/patologia , Dióxido de Tório/efeitos adversos , Acidente Nuclear de Fukushima , Instabilidade Genômica , Humanos , Neoplasias Induzidas por Radiação/genética
13.
Phys Med ; 30(4): 489-96, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24560944

RESUMO

BACKGROUND: The epidemiology of the slightly radioactive contrast agent named Thorotrast presents a very long latency period between the injection and the development of the related pathologies. It is an example of the more general problem posed by a radioactive internal contaminant whose effects are not noteworthy in the short term but become dramatic in the long period. A point that is still to be explored is fluctuations (in space and time) in the localized absorption of radiation by the tissues. METHODS: A Monte Carlo simulation code has been developed to study over a 30-year period the daily absorption of α radiation by µm-sized portions of tissue placed at a distance of 0-100 µm from a model source, that approximates a compact thorium dioxide source in liver or spleen whose size is ≳20 µm. The biological depletion of the daughter nuclei of the thorium series is taken into account. The initial condition assumes chemically purified natural thorium. RESULTS: Most of the absorbed dose is concentrated in a 25-µm thick layer of tissue, adjacent to the source boundary. Fluctuations where a target region with a volume of 1 µm(3) is hit by 3-5 α particles in a day or in a shorter period of time are relevant in a 1-10 µm thick layer of tissue adjacent to the source boundary, where their frequency is larger than the Poisson-law prediction.


Assuntos
Absorção de Radiação , Partículas alfa , Meios de Contraste , Método de Monte Carlo , Dióxido de Tório , Doses de Radiação
14.
JBR-BTR ; 97(4): 254-8, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25603638

RESUMO

We report the CT, surgical and histopathologic findings of a rare case of Hepatic Angiosarcoma (HAS) diagnosed in a 85-year old women 65 years afterThorotrast (Th232) exposure for angiography. At the early arterial phase of dynamic MDCT, peripheral curvilinear and central nodular puddling of contrast produced in the 8 cm tumor.Then progressive contrast filling of the tumor was observed on the delayed scans. Associated pathognomonic signs related to previous Th232 exposure were also found comprising diffuse intrahepatic reticular bands of calcifications, numerous calcified epigastric lymph nodes and a calcified shrunken spleen. Emergency laparotomy was performed because of associated hemoperitoneum. With a delay of 65 years afterThorotrast exposure, this historical case probably represents, to our knowledge, the most delayed presentation of Th232 related HAS ever published.


Assuntos
Meios de Contraste/efeitos adversos , Hemangiossarcoma/induzido quimicamente , Hemangiossarcoma/diagnóstico por imagem , Neoplasias Hepáticas/induzido quimicamente , Neoplasias Hepáticas/diagnóstico por imagem , Dióxido de Tório/efeitos adversos , Idoso de 80 Anos ou mais , Carcinógenos , Diagnóstico Diferencial , Evolução Fatal , Feminino , Hemangiossarcoma/química , Hemangiossarcoma/patologia , Hemangiossarcoma/cirurgia , Humanos , Fígado/diagnóstico por imagem , Fígado/patologia , Fígado/cirurgia , Neoplasias Hepáticas/química , Neoplasias Hepáticas/patologia , Neoplasias Hepáticas/cirurgia , Tomografia Computadorizada Multidetectores/métodos , Dióxido de Tório/análise
15.
Phys Med ; 29(5): 520-30, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23333397

RESUMO

We simulate the α-activity of the Thorium series elements present in the contrast medium named Thorotrast, used until 1960 and cause of certified deaths until today. Assuming, as active components at t=0, (232)Th and (228)Th in the same relative concentration they have in nature, α-activity oscillates for some decades before reaching a stationary value that in absence of biological depletion would be AST =24000Bq/g. Our Montecarlo code generates the nuclear decays of the Thorium series with and without in-vivo biological depletion, arriving to three kinds of results for the activity: 1) Theoretical activity concentration (no biological depletion). Our result is fitted by: A(t)=A(ST).{[1-exp(-t/10)]+[exp(-t/tB)(1-0.8exp(-t/tA))]}, with t in years, tA=1.07.10(-2) years, and tB=2.38 years. 2) Weak biological depletion (228Ra/232 Th equilibrium activity ratio 0.6, 224Ra/228Ra e.a.r 0.9, 10% excretion for 220Rn). The ratio of the activity concentration to the theoretical activity concentration is fitted by: A weak (t)/A(t)=0.61+0.29 exp[-(t/15)2] (t in years). 3) Strong biological depletion (228Ra/232Th e.a.r 0.4, 224Ra/228Ra e.a.r. 0.8, 10% excretion for 220Rn). The ratio of the activity concentration to the theoretical activity concentration is fitted by A(strong)(t)/A(t)=0.44+0.4 exp[-(t/13)2](t in years). We also report fluctuation calculation for two cases where standard statistical behavior is not expected.


Assuntos
Partículas alfa , Tório/química , Modelos Teóricos , Radioquímica , Tório/isolamento & purificação , Dióxido de Tório/química , Fatores de Tempo
16.
Clin Imaging ; 37(3): 583-5, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23313189

RESUMO

This is a case report of a 79-year-old woman who was found to have numerous hyperdense nodular lesions in the upper abdomen, which were incidentally discovered during routine follow-up of a lung nodule. These hyperdense lesions included a lace-like reticular distribution within the liver, multiple extremely dense lymph nodes, and a shrunken hyperdense spleen. We discuss differential considerations for such a constellation of findings and explain why we believe the findings in this case are consistent with prior thorium dioxide exposure. We conclude with a discussion of the pathophysiology and important complications of thorium dioxide exposure and the best imaging modalities for its detection. We believe that this is an important entity that all physicians should be aware of because even though it is seldom seen today, it has characteristic imaging findings and the correct diagnosis is critical given the increased risk of malignancy for which such patients should be screened for.


Assuntos
Neoplasias Pulmonares/diagnóstico por imagem , Doenças Linfáticas/induzido quimicamente , Doenças Linfáticas/patologia , Sistema Fagocitário Mononuclear/efeitos dos fármacos , Sistema Fagocitário Mononuclear/diagnóstico por imagem , Dióxido de Tório/efeitos adversos , Idoso , Meios de Contraste/efeitos adversos , Feminino , Humanos , Achados Incidentais , Neoplasias Pulmonares/complicações , Tomografia Computadorizada por Raios X/métodos
18.
J Hazard Mater ; 241-242: 340-7, 2012 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-23084243

RESUMO

Quantitative leaching of Sr from homogeneous and calcined (Th,Sr) O(2) in dilute perchloric acid medium suggests the possibility of reducing the hazardousness of discharged nuclear fuel by separation of (90)Sr, a prominent fission product at dissolution stage itself rather than the conventional approach of its recovery from high level nuclear waste. Apart from mitigating the radiotoxicity of the nuclear waste, recovered (90)Sr can be employed as a compact heat source and as parent radionuclide for (90)Y (used in therapy radiopharmaceuticals), provided it can be made available at desired high purity. Leaching behavior of few other fission products was also investigated to quantify their contamination in leached Sr. Feasibility of employing extraction chromatography using Sr selective resin was explored in perchloric acid medium. In this context, the distribution coefficients of (85)Sr(II), Th (IV), Zr(IV), Y(III), Pd(II) as well as (152)Eu(III) and (137)Cs (I) were determined under varying nitric acid/perchloric acid concentration and under varying loading conditions of metal ions. Perchloric acid medium appears better than nitric acid medium for preferential leaching of Sr from (Th,Sr)O(2) as well as for uptake of Sr by Sr selective chromatographic resin.


Assuntos
Cromatografia Líquida/métodos , Resíduos Radioativos/prevenção & controle , Radioisótopos de Estrôncio/isolamento & purificação , Estrôncio/química , Dióxido de Tório/química , Tório/química , Cromatografia Líquida/instrumentação , Éteres de Coroa/química , Resinas de Troca Iônica/química , Ácido Nítrico/química , Percloratos/química , Radioisótopos de Ítrio/isolamento & purificação
19.
J Phys Condens Matter ; 24(21): 215405, 2012 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-22575874

RESUMO

Thorium dioxide (ThO(2)) is of great interest to energy research as thorium-based nuclear fuel offers the promise of increased proliferation resistance, longer fuel cycles, higher burn-up and improved wasteform characteristics in the generation of nuclear power. However, understanding of ThO(2) as a nuclear fuel is not as comprehensive as UO(2). In order to improve the atomic level understanding of thorium-based fuels, we have developed eight interatomic potential descriptions of ThO(2) by fitting the experimental lattice parameter, elastic constants and static dielectric constants. Using these interatomic potentials, we have calculated the structural and elastic properties, phase stability, defect formation energies, defect binding energies and complexes as well as the energetics of low-index surfaces. A critical assessment of all the potentials is performed by comparing the predicted properties with available experimental and first-principles calculations.


Assuntos
Modelos Químicos , Modelos Moleculares , Teoria Quântica , Dióxido de Tório/química , Simulação por Computador , Módulo de Elasticidade , Transição de Fase
20.
Radiologe ; 51(12): 1052-7, 2011 Dec.
Artigo em Alemão | MEDLINE | ID: mdl-22089257

RESUMO

The medical management and counseling of persons at high risk due to exposure to chemicals or radiation or due to personal disposition, present an additional challenge for physicians and especially radiologists involved. This article is based on own experiences with patients who had been exposed to Thorotrast. They had been injected with the contrast medium Thorotrast, which was in use world-wide until around 1950. Thorotrast caused a chronic alpha irradiation mainly of the liver (up to 0.4 Gy/a), spleen (1.2 Gy/a) and bone marrow (0.1 Gy/a). For the Thorotrast patients and their physicians the most worrying problem was the risk of primary malignant liver tumors which occurred in more than 20% of the exposed persons, i.e. 100 times more frequently than in a non-exposed control group. The medical and especially radiological experiences with the management of these patients summarize a general aspect of the problem and can be referred to when managing other high risk groups.


Assuntos
Neoplasias Hepáticas/etiologia , Neoplasias Hepáticas/terapia , Neoplasias Induzidas por Radiação/etiologia , Neoplasias Induzidas por Radiação/terapia , Dióxido de Tório/efeitos adversos , Doença Crônica , Meios de Contraste/efeitos adversos , Humanos , Neoplasias Hepáticas/diagnóstico , Neoplasias Induzidas por Radiação/diagnóstico , Compostos Radiofarmacêuticos/efeitos adversos , Medição de Risco , Fatores de Risco
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