RESUMO
Albedo dosemeters for neutron individual monitoring are used worldwide and their response to the same dose can vary by more than one order of magnitude, depending on the neutron workplace spectrum. Two-component albedo dosemeters use two pairs of TLDs, one pair to measure incident neutrons (i) and another to measure albedo neutrons (a), used to corrections to the neutron HP(10). A Workplace Correction Factor (WCF) as a function of the i/a ratio can be plotted from experimental or simulated measurements. This paper uses a Monte Carlo MCNPX simulation of the Alnor albedo dosemeter response to plot WCF × i/a curves for several neutron fields. Experimental results were used to validate the simulation. The use of the proposed curves to calculate WCF can reduce the inaccuracies of the neutron dose assessment for different neutron fields of several facilities. However, it is necessary to be careful with the uncertainties of the i/a values.
Assuntos
Exposição Ocupacional , Monitoramento de Radiação , Proteção Radiológica , Desenho de Equipamento , Método de Monte Carlo , Nêutrons , Exposição Ocupacional/análise , Doses de Radiação , Monitoramento de Radiação/métodos , Proteção Radiológica/métodos , Local de TrabalhoRESUMO
Occupational neutron fields usually have energies from the thermal range to some MeV and the characterization of the spectra is essential for estimation of the radioprotection quantities. Thus, the spectrum must be unfolded based on a limited number of measurements. This study implemented an algorithm based on the bee colonies behavior, named Artificial Bee Colony (ABC), where the intelligent behavior of the bees in search of food is reproduced to perform the unfolding of neutron spectra. The experimental measurements used Bonner spheres and 6LiI (Eu) detector, with irradiations using a thermal neutron flux and three reference fields: 241Am-Be, 252Cf and 252Cf (D2O). The ABC obtained good estimation of the expected spectrum even without previous information and its results were closer to expected spectra than those obtained by the SPUNIT algorithm.
Assuntos
Algoritmos , Comportamento Apetitivo , Abelhas , Nêutrons , Monitoramento de Radiação/instrumentação , Proteção Radiológica/instrumentação , Amerício/análise , Animais , Berílio/análise , Biomimética , Califórnio/análise , Simulação por Computador , Método de Monte Carlo , Doses de Radiação , Monitoramento de Radiação/métodosRESUMO
Brazil has about 300 nuclear medicine services (NMS), 44 of them located in the state of Rio de Janeiro (RJ). Most nuclear medicine staff are routinely monitored for external dose. This paper makes a statistical analysis of all the RJ NMS annual external occupational doses in year 2005. Around 100 professionals of RJ NMS received annual doses >4.0 mSv, considering only external doses, but no one receives doses higher than the mean annual dose limit of 20 mSv. Extremities dosemeters are used by about 10 % of the staff. In some cases, these doses are more than 10 times higher than the dose in thorax. The maximum ratio of extremity dose/thorax dose, in 2005, was 72. This study shows the importance to improve radiation protection procedures in nuclear medicine, mainly because the number of occupational individuals in nuclear medicine and their external doses are increasing.
Assuntos
Medicina Nuclear , Exposição Ocupacional/prevenção & controle , Medicina do Trabalho/normas , Monitoramento de Radiação/métodos , Radiometria/métodos , Brasil , Humanos , Medicina Nuclear/métodos , Medicina do Trabalho/métodos , Fótons , Tomografia por Emissão de Pósitrons/métodos , Doses de Radiação , Proteção Radiológica/métodos , Compostos Radiofarmacêuticos/análise , Tórax/efeitos da radiação , Tomografia Computadorizada de Emissão de Fóton Único/métodos , Recursos HumanosRESUMO
Brazil, a large country, with more than 120,000 workers under individual monitoring for ionising radiation, developed, more than 20 y ago, a centralised data bank for external occupational dose. This old database, however, presented some problems and does not satisfy any more Brazilian present needs, not allowing dose analysis reports, for example. Therefore, a new system that reduces manual tasks, provides system communication support, manages reports and improves data storage management is being developed. This paper describes this new web-based information system, named Brazilian External Occupational Dose Management database system--GDOSE.
Assuntos
Exposição Ocupacional/prevenção & controle , Monitoramento de Radiação/métodos , Proteção Radiológica/métodos , Radiação Ionizante , Radiometria/métodos , Brasil , Sistemas Computacionais , Bases de Dados Factuais , Humanos , Armazenamento e Recuperação da Informação , Internet , Sistema de RegistrosRESUMO
Instituto de Radioproteção e Dosimetria, a Brazilian government research institute, provides individual monitoring services since 1972. Its dosemeters are: film-based thorax for whole body photons, thermoluminescence dosimetry (TLD) albedo for whole body neutrons and TLD ring for extremity photons. About 6000 radiation workers are currently being monitored with film dosemeters in 256 different facilities in Brazil, most of them working in health-related activities. Around 400 Brazilian radiation workers are monitored with TLD albedo neutron monitor and about 500 workers use TLD rings. This paper describes the monitoring systems used, presents the results obtained in internal quality programs and in intercomparison exercises and analyses the measured dose values from 1985 to 2009.