RESUMO
When a cost-benefit analysis is applied to the optimization of practices involving radiation protection, the alpha value is used to determine the amount of money required to be invested in a practice to minimize radiation doses to acceptable levels. The alpha value is often linked to the gross domestic product (GDP) per capita, so the monetary reference value of person-Sievert can often be different in each country. Evaluation of the alpha value in Brazil was performed in 1993 and 2000 making use of the procedure advised by ICRP to produce projections up to 2015 and subsequently in 2004 by using the procedure recommended by the IAEA. This paper, in response to the social and economic situation in Brazil, calculates the alpha value and compares it with the projections of the 1993 and 2000 papers and includes a dollar correction to take account of the differences in the purchasing power from that time. This procedure illustrates the significant gap of value in use and that the actual value should be two to three times higher. By GDP per capita, the authors could calculate the alpha value updated to various countries including the European Union and compare them with the official value currently in use. In conclusion, it is believed that all countries that adopt an alpha value should upgrade it to the present day.
Assuntos
Produto Interno Bruto , Proteção Radiológica/economia , Brasil , Análise Custo-Benefício , HumanosRESUMO
This work aims to evaluate the potential risks of incidents in nuclear research reactors. For its development, two databases of the International Atomic Energy Agency (IAEA) were used: the Research Reactor Data Base (RRDB) and the Incident Report System for Research Reactor (IRSRR). For this study, the probabilistic safety analysis (PSA) was used. To obtain the result of the probability calculations for PSA, the theory and equations in the paper IAEA TECDOC-636 were used. A specific program to analyse the probabilities was developed within the main program, Scilab 5.1.1. for two distributions, Fischer and chi-square, both with the confidence level of 90 %. Using Sordi equations, the maximum admissible doses to compare with the risk limits established by the International Commission on Radiological Protection (ICRP) were obtained. All results achieved with this probability analysis led to the conclusion that the incidents which occurred had radiation doses within the stochastic effects reference interval established by the ICRP-64.
Assuntos
Centrais Elétricas , Proteção Radiológica , Liberação Nociva de Radioativos , Gestão da Segurança , Humanos , Energia Nuclear , Probabilidade , Monitoramento de RadiaçãoRESUMO
Analytical geometric models for the bones of the knee region have been developed. A survey was done on real pieces to obtain the dimensions of the geometric sections used in each model. The dependence of the section dimensions on the bone length and the estimated dimensions of the bones for a 1.70 m tall person are presented. A parameter that attempts to relate the person's height to the bone length was included. Using reference data for the tissues and for bone composition, the models represent 8.7% (each knee) of a 10 kg skeleton and present the following densities: femur and tibia 1590 kg m(-3), fibula 1660 kg m(-3) and patella 1720 kg m(-3).
Assuntos
Osso e Ossos/anatomia & histologia , Osso e Ossos/fisiologia , Articulação do Joelho/anatomia & histologia , Articulação do Joelho/fisiologia , Modelos Biológicos , Radiometria/métodos , Radiometria/normas , Simulação por Computador , Humanos , Doses de RadiaçãoRESUMO
Radioactive patients may expose others after radiopharmaceutical administrations, and evaluation of the absorbed dose or exposure rates close to patients is important in keeping radiation doses as low as reasonably achievable. Two theoretical exposure models, point source and line source models, are frequently used to calculate exposure or dose rates without the support of actual measurements. If measurements of exposure rates were performed near patients, an experimental exposure model could be implemented. When measurements of exposure rates are performed, these measurements are made inside therapy rooms or other confined places, in which case scattered radiation may significantly influence the measurements. In this study we measured exposure rates from radioactive patients without the influence of scattered radiation and determined correction factors for the theoretical exposure models. The exposure rates from a total of 110 radioactive patients were measured at 1.0 h after oral administration of Na131I for thyroid therapy; the results +/-1 SD at distances of 0.5, 1.0, 1.5, 2.0, 3.0, and 4.0 m in front of the patients were (29 +/- 6), (9.9 +/- 1.7), (4.6 +/- 0.9), (2.7 +/- 0.5), (1.31 +/- 0.25) and (0.74 +/- 0.12) x 10(-10) C kg(-1) MBq(-1) h(-1) [1.0 x 10(-10) C kg(-1) MBq(-1) h(-1) = 14.34 x 10(-6) R mCi(-1) h(-1)], respectively. To obtain more accurate estimates of the actual exposure rates from patients using the theoretical exposure models, we found that correction factors should be applied; the functions CFEM = 1.19 + 32.80e(5.92D) and CFLS = 0.022LnD + 0.639 describe these correction factors for distances less than or equal to 1.0 m from the patients for experimental and line source exposure models, respectively. The function that describes the correction factors to the point source model is CFPS = 0.224LnD + 0.638 at the same distances; applying these correction factors leads to a reduction from 56% to 1% in the difference between measured exposure rates and theoretical exposure rates calculated by the point source exposure model at a distance of 1.0 m from patients. The results given here provide more accuracy in evaluation of exposure rates and consequently absorbed doses near radioactive patients and allow for more effective radiological protection procedures during patient management.
Assuntos
Radioisótopos do Iodo/uso terapêutico , Monitoramento de Radiação , Proteção Radiológica , Compostos Radiofarmacêuticos/uso terapêutico , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Hipertireoidismo/radioterapia , Radioisótopos do Iodo/efeitos adversos , Masculino , Pessoa de Meia-Idade , Compostos Radiofarmacêuticos/efeitos adversos , Neoplasias da Glândula Tireoide/radioterapiaRESUMO
In several countries, low-level radioactive wastes are treated and stored awaiting construction and operation of a final repository. In some cases, interim storage may be extended for decades requiring special attention regarding security issues. The International Atomic Energy Agency (IAEA) recommends segregation of wastes that may be exempted from interim storage or ultimate disposal. The paper presents a method to optimize the decision making process regarding exemption vs. interim storage or ultimate disposal of these wastes.
Assuntos
Resíduos Radioativos , Gerenciamento de Resíduos/normas , Gerenciamento de Resíduos/economiaRESUMO
The measurement of exposure rates is fundamentally important in the release of patients given radioactive materials and for keeping the exposures of others as low as reasonable achievable. Similar measurement methodologies have generally been used for point and extended sources, but this approach may lead to methodological errors in calculating radiation dose estimates. In this study, nuclear medicine patients who received high activities of Na131I for therapy were monitored using different measurement methodologies, and the results showed that the usual measurement performed at 1.0 m in front of the body resulted in a mean error of 40% between experimental and theoretical exposure rates. The best measurements were obtained when performed at 2.0 m in front of the patients. With this approach, the error was about 2% between experimental and theoretical values. These findings suggest a new methodology for patients' measurement in nuclear medicine and could be useful for personal monitoring in cases of radiological emergencies involving 131I ingestion.
Assuntos
Hipertireoidismo/radioterapia , Proteção Radiológica , Neoplasias da Glândula Tireoide/radioterapia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Radioisótopos do Iodo/uso terapêutico , Masculino , Pessoa de Meia-Idade , Medicina Nuclear , Doses de Radiação , Monitoramento de Radiação , Radiometria , Reprodutibilidade dos Testes , Estudos RetrospectivosRESUMO
Nuclear medicine procedures that use I activity represent significant sources of potential absorbed dose to medical staff, volunteers, and the general public. The potential exposures are due principally from exposures to excreted and retained activities in the patients' bodies. In general, exposure rate decreases in a simple exponential manner. The average effective half-life found for all patients in the study reported here is 11.41 +/- 0.02 h; this information may be used in guidelines on the management of patients in thyroid cancer therapy and for general radioprotection practice.
Assuntos
Radioisótopos do Iodo/farmacocinética , Radioisótopos do Iodo/uso terapêutico , Neoplasias da Glândula Tireoide/metabolismo , Neoplasias da Glândula Tireoide/radioterapia , Contagem Corporal Total/métodos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Carga Corporal (Radioterapia) , Feminino , Meia-Vida , Humanos , Radioisótopos do Iodo/análise , Radioisótopos do Iodo/química , Masculino , Taxa de Depuração Metabólica , Pessoa de Meia-Idade , Compostos Radiofarmacêuticos/análise , Compostos Radiofarmacêuticos/química , Compostos Radiofarmacêuticos/farmacocinética , Compostos Radiofarmacêuticos/uso terapêutico , Eficiência Biológica Relativa , Estudos RetrospectivosRESUMO
The evaluation of the absorbed dose from radioactive patients during the treatment of thyroid disease is an important factor in establishing precautions in these procedures, and the I retention/excretion by patients' bodies provides additional information to medical and radioprotection service. In 94 patients, the measurement of exposure rates was performed over 7 d following NaI administration, and the rates permitted the study of the dynamics of excretion and the potential dose evaluation. The administered activities ranged from 3.7 GBq (100 mCi) to 16.65 GBq (450 mCi), and the results proved that the majority of the activity is excreted by patients in the first 3 d after NaI administration. The average (131)I activity excreted at 24, 48, 72, 96, and 120 h after oral administration was (72 +/- 10), (91 +/- 6), (97 +/- 3), (98.9 +/- 1.5), and (99.6 +/- 0.7)%, respectively. According to the administered activity, the evaluation of the accumulated absorbed dose from patients ranged from 3.0 +/- 0.7 to 8.4 +/- 1.1 mSv at 1 m and 1.2 +/- 0.4 to 3.2 +/- 0.4 mSv at 2 m. The data reported here are important to radioprotection policy and to add to and improve on the guidelines reported in U.S. NRC Regulatory Guide 8.39.
Assuntos
Radioisótopos do Iodo/farmacocinética , Radioisótopos do Iodo/uso terapêutico , Modelos Biológicos , Medição de Risco/métodos , Neoplasias da Glândula Tireoide/metabolismo , Neoplasias da Glândula Tireoide/radioterapia , Contagem Corporal Total/métodos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Carga Corporal (Radioterapia) , Brasil/epidemiologia , Simulação por Computador , Feminino , Meia-Vida , Humanos , Radioisótopos do Iodo/análise , Radioisótopos do Iodo/química , Masculino , Taxa de Depuração Metabólica , Pessoa de Meia-Idade , Compostos Radiofarmacêuticos/análise , Compostos Radiofarmacêuticos/química , Compostos Radiofarmacêuticos/farmacocinética , Compostos Radiofarmacêuticos/uso terapêutico , Eficiência Biológica Relativa , Estudos Retrospectivos , Fatores de RiscoRESUMO
Spent or disused sealed radiation sources--no longer needed sources--may represent a risk of radiological accident or may be a target for criminal acts in countries where final disposal options are unavailable and where an increasing number of sources are being kept in extended storage. In developing countries, thousands of radium needles, teletherapy sources, oil well logging neutron sources, and miscellaneous industrial radioactive gauges are annually collected as waste and stored in research institutes. The objectives of the study described in this paper are to inventory such sources in Brazil, including those presently in use and those already collected as waste, and to design a dedicated repository where spent sources could be disposed of properly. The inventory of sources in Brazil and the concept of the repository are presented and its feasibility is discussed.
Assuntos
Documentação/métodos , Documentação/normas , Proteção Radiológica/métodos , Resíduos Radioativos/prevenção & controle , Eliminação de Resíduos/métodos , Eliminação de Resíduos/normas , Medição de Risco/métodos , Gestão da Segurança/métodos , Brasil , Equipamentos e Provisões , Arquitetura de Instituições de Saúde , Estudos de Viabilidade , Lesões por Radiação/prevenção & controle , Gerenciamento de Resíduos/métodos , Gerenciamento de Resíduos/normasRESUMO
As relações entre trabalhadores, pacientes e médicos diante dos princípios básicos de proteção radiológica, têm, neste trabalho, uma introdução histórica que dá ênfase ao seu desenvolvimento até se chegar ao período atual. É abordada a evolução dos conhecimentos científicos quanto aos benefícios e malefícios advindo da utilização das radiações ionizantes nas atividades humanas. Tais princípios (justificação, otimização e limitação) são tratados de modo a fornecer uma visão ampla de seus campos de aplicação. No princípio da otimização são introduzidas as técnicas de ajuda para a tomada de decisão utilizadas em proteção radiológica. No princípio da limitação de doses foi introduzido o conceito de limite vinculado a um determinado segmento da população ou a uma determinada atividade humana. Com relação ao atual relacionamento entre equipe médica e paciente, discute-se a mudança de filosofia no que diz respeito à dose de radiação ministrada, que deve ser mínima com relação aos objetivos de diagnose ou cura. Para tanto devem ser seguidas as recomendações da ICRP - International Commision on Radiological Protection. A radiação pode trazer benefícios desde que utilizada com racionalidade, eficiência e cuidados. A radiação não deve ser temida, mas respeitada.
Assuntos
Medicina do Trabalho , Proteção Radiológica/normas , Radiação IonizanteRESUMO
The mathematical phantom of the Brazilian man was developed because many anatomical differences exist between South Americans, Europeans and North Americans. The objective of this work was to compare specific absorbed fractions (SAF) obtained for a model of the Brazilian adult male with those for the reference adult calculated by Snyder et al. in 1974 and to evaluate the importance of these new values in calculating radiation doses in diagnosis and therapy. The length and mass of the total body for the Brazilian man phantom were obtained from tables provided by the Brazilian government (IBGE) in which the masses of organs were measured atautopsy. Monte Carlo methods (using the ALGAM-97 computer code) were applied to calculate SAF for internal organs and the total body. The mathematical phantom designed by Snyder et al. represents very closely Reference Man, as defined in ICRP publication 23. SAF for the whole body were not more than 15% different between the two phantoms. The differences between both models are more significant for individual organs. When the source organ is the lung and red marrow is the target, for initial photon energy of 10 keV, the results obtained indicate that marrow receives 64% more dose in Brazilian model than in the Reference Man model. Eighty tables were made for 97 distinct organs (target-source) and the comparison made between the, Brazilian man and Reference man.
Assuntos
Imagens de Fantasmas , Radioisótopos/administração & dosagem , Adulto , Brasil , Humanos , Masculino , Modelos Anatômicos , Método de Monte Carlo , Tamanho do Órgão , Doses de Radiação , Radioisótopos/farmacocinéticaRESUMO
As doses individuais de duas décadas do H.C.F.M.R.P-USP foram analisadas. Desta análise as doses médias anuais individuais de vários serviços do hospital foram comparadas, assim como as doses por categoria de trabalhador Dos dados obtidos classificamos os trabalhadores nas condições de trabalho A e B recomendadas pela ICRP 35. Também foi possível comparar três tipos de monitoração individual (filme, CaSO4 e LiF + CaSO4), realizadas por laboratórios diferentes, observando-se boa concordância entre eles.