RESUMO
Whole-body counters (WBC) are used in internal dosimetry forin vivomonitoring in radiation protection. The calibration processes of a WBC set-up include the measurement of a physical phantom filled with a certificate radioactive source that usually is referred to a standard set of individuals determined by the International Commission on Radiological Protection (ICRP). The aim of this study was to develop an anthropomorphic and anthropometric female physical phantom for the calibration of the WBC systems. The reference female computational phantom of the ICRP, now called RFPID (Reference Female Phantom for Internal Dosimetry) was printed using PLA filament and with an empty interior. The goal is to use the RFPID to reduce the uncertainties associated within vivomonitoring system. The images which generated the phantom were manipulated using ImageJ®, Amide®, GIMP®and the 3D Slicer®software. RFPID was split into several parts and printed using a 3D printer in order to print the whole-body phantom. The newly printed physical phantom RFPID was successfully fabricated, and it is suitable to mimic human tissue, anatomically similar to a human body i.e., size, shape, material composition, and density.
Assuntos
Imagens de Fantasmas , Impressão Tridimensional , Contagem Corporal Total , Humanos , Feminino , Contagem Corporal Total/métodos , Calibragem , Proteção Radiológica/métodos , Proteção Radiológica/instrumentação , Radiometria/métodos , Radiometria/instrumentação , AntropometriaRESUMO
The objective of this work is to obtain fluence to effective dose conversion coefficients for neutron point sources, using the GEANT4 toolkit. These calculations aim to investigate the aspects of neutron transport in the human body through Monte Carlo simulation using the International Commission on Radiological Protection (ICRP) voxel phantoms, described in its publication 110. A benchmarking of the code was made for the case of monoenergetic plane parallel neutron beam in the antero-posterior (AP) irradiation geometry and organ absorbed dose conversion coefficients were compared with those found in the ICRP publication 116. The results showed good agreement with ICRP results in the studied energy range. Conversion coefficients were presented for specific conditions with 241Am-Be and 252Cf point neutron sources 1 m away from the phantom in the AP geometry.
Assuntos
Modelos Biológicos , Nêutrons , Imagens de Fantasmas , Proteção Radiológica/métodos , Radiometria/métodos , Contagem Corporal Total/métodos , Amerício/análise , Antropometria , Carga Corporal (Radioterapia) , Califórnio/análise , Simulação por Computador , Humanos , Doses de Radiação , Eficiência Biológica RelativaRESUMO
The estimation of the dose and the irradiated fraction of the body is important information in the primary medical response in case of a radiological accident. The PCC-R assay has been developed for high-dose estimations, but little attention has been given to its applicability for partial-body irradiations. In the present work we estimated the doses and the percentage of the irradiated fraction in simulated partial-body radiation exposures at high doses using the PCC-R assay. Peripheral whole blood of three healthy donors was exposed to doses from 0-20 Gy, with 6°Co gamma radiation. To simulate partial body irradiations, irradiated and non-irradiated blood was mixed to obtain proportions of irradiated blood from 10-90%. Lymphocyte cultures were treated with Colcemid and Calyculin-A before harvest. Conventional and triage scores were performed for each dose, proportion of irradiated blood and donor. The Papworth's u test was used to evaluate the PCC-R distribution per cell. A dose-response relationship was fitted according to the maximum likelihood method using the frequencies of PCC-R obtained from 100% irradiated blood. The dose to the partially irradiated blood was estimated using the Contaminated Poisson method. A new D0 value of 10.9 Gy was calculated and used to estimate the initial fraction of irradiated cells. The results presented here indicate that by PCC-R it is possible to distinguish between simulated partial- and whole-body irradiations by the u-test, and to accurately estimate the dose from 10-20 Gy, and the initial fraction of irradiated cells in the interval from 10-90%.
Assuntos
Bioensaio/métodos , Aberrações Cromossômicas/efeitos da radiação , Análise Citogenética/métodos , Interpretação Estatística de Dados , Linfócitos/fisiologia , Linfócitos/efeitos da radiação , Contagem Corporal Total/métodos , Carga Corporal (Radioterapia) , Células Cultivadas , Relação Dose-Resposta à Radiação , Raios gama , Humanos , Linfócitos/citologia , Doses de Radiação , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Irradiação Corporal Total/métodosRESUMO
Internal exposures may occur in nuclear power plants, radioisotope production, and in medicine and research laboratories. Such practices require quick response in case of accidents of a wide range of magnitudes. This work presents the design and calibration of a mobile laboratory for the assessment of accidents involving workers and the population as well as for routine monitoring. The system was set up in a truck with internal dimensions of 3.30 m × 1.60 m × 1.70 m and can identify photon emitters in the energy range of 100-3,000 keV in the whole body, organs, and in urine. A thyroid monitor consisting of a lead-collimated NaI(Tl)3" × 3" (7.62 × 7.62 cm) detector was calibrated with a neck-thyroid phantom developed at the IRD (Instituto de Radioproteção e Dosimetria). Whole body measurements were performed with a NaI(Tl)8" × 4" (20.32 × 10.16 cm) detector calibrated with a plastic-bottle phantom. Urine samples were measured with another NaI(Tl) 3" × 3" (7.62 × 7.62 cm) detector set up in a steel support. Standard solutions were provided by the National Laboratory for Metrology of Ionizing Radiation of the IRD. Urine measurements are based on a calibration of efficiency vs. energy for standard volumes. Detection limits were converted to minimum committed effective doses for the radionuclides of interest using standard biokinetic and dosimetric models in order to evaluate the applicability and limitations of the system. Sensitivities for high-energy activation and fission products show that the system is suitable for use in emergency and routine monitoring of individuals under risk of internal exposure by such radionuclides.
Assuntos
Bioensaio/instrumentação , Bioensaio/métodos , Laboratórios , Unidades Móveis de Saúde , Exposição Ocupacional/análise , Radioisótopos/metabolismo , Radiometria/instrumentação , Radiometria/métodos , Contagem Corporal Total/instrumentação , Calibragem , Radioisótopos de Césio , Humanos , Radioisótopos do Iodo , Limite de Detecção , Modelos Biológicos , Imagens de Fantasmas , Radioisótopos/urina , Medição de Risco , Glândula Tireoide/metabolismo , Contagem Corporal Total/métodosRESUMO
The goal of the present paper was to assess a method for estimating the thermal radiation absorbed by dairy cows (0.875 Holstein-0.125 Guzerath) on pasture. A field test was conducted with 472 crossbred dairy cows in three locations of a tropical region. The following environmental data were collected: air temperature, partial vapour pressure, wind speed, black globe temperature, ground surface temperature and solar radiation. Average total radiation absorbed by animals was calculated as R(abs) = 640.0 +/- 3.1 W .m(-2). Absorbed short-wave radiation (solar direct, diffuse and reflected) averaged 297.9 +/- 2.7 W m(-2); long wave (from the sky and from terrestrial surfaces) averaged 342.1 +/- 1.5 W m(-2). It was suggested that a new environmental measurement, the effective radiant heat load (ERHL), could be used to assess the effective mean radiant temperature (T*(mr)). Average T*(mr) was 101.4 +/- 1.2 degrees C, in contrast to the usual mean radiant temperature, T(mr) = 65.1 +/- 0.5 degrees C. Estimates of T*(mr) were considered as more reliable than those of T (mr) in evaluating the thermal environment in the open field, because T (mr) is almost totally associated only with long wave radiation.
Assuntos
Regulação da Temperatura Corporal/fisiologia , Regulação da Temperatura Corporal/efeitos da radiação , Bovinos/fisiologia , Exposição Ambiental/análise , Eficiência Biológica Relativa , Energia Solar , Contagem Corporal Total/métodos , Animais , Bioensaio/métodos , Simulação por Computador , Temperatura Alta , Modelos Biológicos , VentoRESUMO
The objective of this work is to develop procedures for internal monitoring of (18)F to be applied in cases of possible incorporation of fluoride and (18)FDG, using in vivo and in vitro methods of measurements. The Na I (Tl) 8" x 4" scintillation detector installed at IRD-Whole Body Counter was calibrated for measurements with a whole body anthropomorphic phantom, simulating homogeneous distribution of (18)F in the body. The NaI(Tl) 3"x 3" scintillation detector installed at the IRD-Whole Body Counter was calibrated for in vivo measurements with a brain phantom inserted in an artificial skull, simulating (18)FDG incorporation. The HPGe detection system installed at the IRD-Bioassay Laboratory was calibrated for in vitro measurements of urine samples with 1 liter plastic bottles containing a standard liquid source. A methodology for bioassay data interpretation, based on standard ICRP models edited with the software AIDE-version 6, was established. It is concluded that in vivo measurements have sufficient sensitivity for monitoring (18)F in the forms of fluoride and (18)FDG. The use of both in vitro and in vivo bioassay data can provide useful information for the interpretation of bioassay data in cases of accidental incorporation in order to identify the chemical form of (18)F incorporated.
Assuntos
Radioisótopos de Flúor/metabolismo , Fluordesoxiglucose F18/metabolismo , Exposição Ocupacional , Compostos Radiofarmacêuticos/metabolismo , Contagem Corporal Total , Brasil , Humanos , Imagens de Fantasmas , Contagem de Cintilação/instrumentação , Contagem de Cintilação/métodos , Contagem Corporal Total/instrumentação , Contagem Corporal Total/métodosRESUMO
Absorbed fraction (AF) calculations to the human skeletal tissues due to alpha particles are of interest to the internal dosimetry of occupationally exposed workers and members of the public. The transport of alpha particles through the skeletal tissue is complicated by the detailed and complex microscopic histology of the skeleton. In this study, both Monte Carlo and chord-based techniques were applied to the transport of alpha particles through 3-D microCT images of the skeletal microstructure of trabecular spongiosa. The Monte Carlo program used was 'Visual Monte Carlo--VMC'. VMC simulates the emission of the alpha particles and their subsequent energy deposition track. The second method applied to alpha transport is the chord-based technique, which randomly generates chord lengths across bone trabeculae and the marrow cavities via alternate and uniform sampling of their cumulative density functions. This paper compares the AF of energy to two radiosensitive skeletal tissues, active marrow and shallow active marrow, obtained with these two techniques.
Assuntos
Osso e Ossos/fisiologia , Modelos Biológicos , Contagem Corporal Total/métodos , Partículas alfa , Bioensaio/métodos , Simulação por Computador , Humanos , Internacionalidade , Cinética , Método de Monte Carlo , Especificidade de Órgãos , Doses de Radiação , Eficiência Biológica Relativa , Sensibilidade e Especificidade , Especificidade da Espécie , Distribuição TecidualRESUMO
Cumulative exposure to radon can be evaluated by measuring 210Pb in bone. The skull and knee are two convenient parts of the skeleton for in vivo measuring 210Pb because these regions of the body present a high concentration of bone, the detectors are easily positioned and the likelihood of cross contribution from other organs or tissues is low. A radiological survey of non-uranium mines in Brazil indicated that an underground coal mine in Paraná, located in the south of Brazil, exhibited a high radon concentration. In vivo measurements of 32 underground coal miners were performed in the IRD-CNEN Whole Body Counter shielded room using an array of four high-resolution germanium detectors. Estimations of 210Pb in the total skeleton were determined from direct in vivo measurements of 210Pb in the head and knees. In vivo measurements of 210Pb in 6 out of 32 underground coal miners ranged from 80 to 164 Bq, suggesting that these workers were significantly exposed to 222Rn.
Assuntos
Articulação do Joelho/metabolismo , Radioisótopos de Chumbo/metabolismo , Mineração , Modelos Biológicos , Exposição Ocupacional/análise , Radônio/metabolismo , Crânio/metabolismo , Contagem Corporal Total/métodos , Algoritmos , Bioensaio/métodos , Brasil , Carvão Mineral , Simulação por Computador , Humanos , Internacionalidade , Radioisótopos de Chumbo/análise , Doses de Radiação , Proteção Radiológica/métodos , Radônio/análise , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
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.