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This paper presents a fast and automatic flow-based method to extract 131I from biological samples and hospital waste, previous to liquid scintillation detection. 131I is a radionuclide extensively used in Nuclear Medicine due to their beta and gamma disintegrations, whereby hospitals have to manage the associated waste generation. The automatic developed system is based on Lab-On-Valve (LOV) flow-technique exploiting Cl-resin (135 mg per extraction). This methodology allows performing sample extractions and measurements on the same day, since the extraction frequency takes 1.4-4 h-1, depending on the analysed sample volume, plus up to 2 h of measurement for each vial. 131I is retained as iodine ion and eluted with sodium sulphide 0.2 mol L-1. The maximum sample volume that can be preconcentrated is 20 mL, reaching an extraction efficiency of 85 ±â€¯5%. The minimum detectable activity (MDA) is 0.05 Bq, showing a precision of 7% RSD (n = 5). Both, biological samples (urine and saliva) and hospital waste samples can be satisfactorily analysed by the proposed system, obtaining recoveries between 90 and 110%. The developed method is then suitable to implement in hospitals, improving the surveillance of the 131I environmental release.

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Recent studies have shown Hg methylation in mangrove sediments, however, little is known about the different microorganism consortia involved. We investigated the participation of prokaryotes in general, iron-reducing bacteria-IRB, sulfate-reducing bacteria-SRB, methanogens and fungi in Hg methylation and sulfate reduction rates (SRR) in mangrove sediments using iron amendments for IRB and specific inhibitors for the other microorganisms. Sediment samples were collected from two mangrove zones, tidal flat and mangrove forest (named root sediments). Samples were incubated with 203Hg or 35SO42- and Me203Hg/35Sulfur were measured by liquid scintillation. Methylmercury (MeHg) formation was significantly reduced when SRB (87.7%), prokaryotes (76%) and methanogens (36.5%) were inhibited in root sediments, but only SRB (51.6%) and prokaryotes (57.3%) in tidal flat. However, in the tidal flat, inhibition of methanogens doubled Hg methylation (104.5%). All inhibitors (except fungicide) significantly reduced SRR in both zones. In iron amended tidal flat samples, Hg methylation increased 56.5% at 100 µg g-1 and decreased at 500 and 1000 µg g-1 (57.8 and 82%). In the roots region, however, MeHg formation gradually decreased in response to Fe amendments from 100 µg g-1 (37.7%) to 1000 µg g-1 (93%). SRR decreased in all iron amendments. This first simultaneous evaluation of Hg methylation and sulfate-reduction and of the effect of iron and inhibitors on both processes suggest that SRB are important Hg methylators in mangrove sediments. However, it also suggests that SRB activity could not explain all MeHg formation. This implies the direct or indirect participation of other microorganisms such as IRB and methanogens and a complex relationship among these groups.

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RESUMO Uma revisão da determinação de alfa e beta total em água, usando espectrometria de cintilação em meio líquido, é apresentada. Foram identificados os principais fatores que influenciam a exatidão e a repetibilidade dos resultados analíticos: pré-concentração térmica, tipo de ácido, janela de contagem e padrão de calibração. Um procedimento analítico foi estabelecido e aplicado a amostras de água de abastecimento público do estado de Goiás para avaliação das radioatividades alfa e beta total. O resumo estatístico dos dados foi realizado por meio dos métodos de análise de dados censurados. Os resultados estão consistentes com os valores de referência do Ministério da Saúde.

ABSTRACT A review to determine the gross alpha and beta in water by using liquid scintillation spectrometry is presented. The main factors that influence the accuracy and repeatability of the analytical results are: thermal pre-concentration, acid type, counting window, and calibration standard. Accordingly, an analytical procedure was established and carried out to samples of the public water supplies in the state of Goiás, Brazil, to evaluate the gross alpha and beta radioactivities. The statistical summary of data was conducted by using analysis methods of censored data. The results comply with the guideline values from the Brazilian Department of Health.

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Mercury (Hg) and methylmercury (MeHg) are highly toxic and poorly studied in mangroves. Burrowing Uca crabs change sediment topography and biogeochemistry and thus may affect Hg distribution and MeHg formation. We studied added (203)Hg distribution, Me(203)Hg formation and sulfate reduction rates (SRR) in sediment aquariums containing Uca leptodactyla; and analyzed profiles of Me(203)Hg formation and SRR in sediment cores from two mangroves with distinct environmental impacts. MeHg formation and SRR were higher in the top (≤6cm) sediment and there was no significant difference in Hg methylation in more or less impacted mangroves. In aquariums, crab bioturbation favored Hg retention in the sediment. In the treatment without crabs, Hg volatilization and water Hg concentrations were higher. Hg methylation was higher in bioturbated aquariums but SRR were similar in both treatments. These findings suggest that bioturbating activity favors Hg retention in sediment but also promotes MeHg formation near the surface.

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Control samples of scintillation liquids - Phaeozem soil mixtures were prepared with different scintillation liquids as the support electrolyte, Install Gel® XF, (Ultima Gold AB™ and Ultima Gold XR™), to construct the polarization curves, and to select the cell potential with the highest mass transfer to remove 24Na (15 h) and 99mTc (6 h) as radiotracers from polluted Phaeozem soil. During the electrokinetic treatment (EKT), the removal of radionuclides contained in scintillation liquids absorbed in Phaeozem soil, liquid phase was characterized by Gas Chromatography coupled with a Flame Ionization Detector (GC-FID) and Fourier Transform Infrared Spectrometry (FTIR), solids by FTIR, before and after the application of cell potential. In this sense, the support electrolyte was selected based on the highest current generated (1 mA), as in the case of scintillation liquid 50% Ultima Gold XR™ + 50% Water (1:1), which was used for 6 h in the presence of a mesh and a titanium rod, as anode and cathode, respectively. Finally, the removal percentage accumulated in the liquid phase after the EKT of Phaeozem soil polluted by 99mTc was 61% close to the anode after 4 h. It was also 61% for 24Na close to cathode after 2 h, and after 4 h it was 71.8%.

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It is proposed a method for the determination of (226)Ra in offshore platform liquid effluent samples (produced water). The method is based on a two-phase liquid scintillation counting system and allows for the direct and simple determination of (226)Ra content. Samples with high barium content may also have high (226)Ra concentration. Therefore, the sample volume is based on the barium concentration and ranges from 10 mL to 100 mL. Our new method was tested using multiple real samples and was compared with the BaSO4 precipitation method. The results based on the LSC were 30% higher than the precipitation method, which is attributed to the self-absorption of alpha particles in the BaSO4 precipitate. The determination of both (226)Ra and (228)Ra in the liquid effluent of offshore oil platforms is mandatory in Brazil. Thus, a second method of accurately assessing (228)Ra content remains necessary.

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The presence and formation of methylmercury (MMHg), a highly toxic form of Hg, in mangrove ecosystems is poorly studied. Therefore the aim of this study was to evaluate mercury methylation potentials in sediment, litter and root samples (Avicennia shaueriana and Spartina alterniflora) from different regions of a mangrove ecosystem, as well as the influence of salinity on methylation. Sediment was sampled under different depths and in mangrove regions with different plant covers and salinities. All samples were incubated with (203)Hg and MM(203)Hg was extracted and measured by liquid scintillation. MMHg was formed in all samples and sites tested including plant roots and litter. Higher Hg methylation was found in the superficial fraction of sediments (0.47-7.82%). Infralittoral sandy sediment had low MMHg formation (0.44-1.61%). Sediment under Rhizophora mangle had lower MMHg formation (0.018-2.23%) than under A. shaueriana (0.2-4.63%) and Laguncularia racemosa (0.08-7.82). MMHg formation in sediment tended to increase with salinity but the differences were not significant. Therefore, MMHg formation occurs in different sites of mangrove ecosystems and may be an important threat that requires further study.

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El trabajo muestra los intervalos de monitoreo que se pueden utilizar en el Laboratorio de Contaminación Interna del Centro de Protección e Higiene de las Radiaciones para medir directamente en la glándula tiroides los radionúclidos y . Se emplearon dos sistemas de medición, uno con un detector de centelleo y otro con un detector Phoswich. Ambos detectores se ubicaron dentro de una cámara de bajo fondo de 2.5 x 2.5 x 2.5 m de dimensión recubierta con 15 cm de acero, 3 mm de plomo, 1.8 mm de estaño, y 1.5 mm de cobre. Se calculó la actividad mínima detectable para cada sistema y en función de esta se determinaron los intervalos de monitoreo aplicables, de forma tal que una incorporación correspondiente al 5 % del límite anual de incorporación se pueda detectar. Se obtuvo que para el , todos los intervalos evaluados (120, 90, 60, 30, 14, y 7 días) se pueden utilizar en el monitoreo con ambos sistemas. En el caso del radionúclido , con la instalación del detector de centelleo solo se pueden aplicar los intervalos de 120, 90, y 60 días, y para la instalación con el Phoswich, todos los evaluados.

This paper shows the monitoring intervals that can be used in the Internal Contamination Laboratory of the Center for Radiation Protection and Hygiene for direct measurement of the radionuclides I-125 and I-129 in the thyroid gland. Two measuring systems were used, one of them with a scintillation detector and the other one with a Phoswich detector. Both detectors were placed inside a low background shielding chamber (2.5 x 2.5 x 2.5 m) coated with 15 cm of steel, 3 mm of lead, 1.8 mm of tin and 1.5 mm of copper. The minimum detectable activity for each system was calculated, and based on this, the applicable monitoring intervals were determined, so that an intake corresponding to 5 % of the Annual Intake Limit can be detected. The results showed that for the radionuclide I-125 all the intervals tested (120, 90, 60, 30, 14 and 7 days) can be used in monitoring both systems. In the case of the radionuclide I-129, only the intervals of 120, 90 and 60 days can be implemented by using the scintillation detector whereas for the Phoswich detector, all the tested intervals can be used.

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A new facility for neutron tomography has been installed at the IEA-R1 nuclear research reactor of IPEN-CNEN/SP. A tomography can be obtained in 400 s and the spatial resolution in the image is 263 µm. The neutron dose per tomography, in the video camera used for image capture, is only 21 µSv, assures very few damages in its CCD sensor. Some selected objects were investigated and the obtained 3D images demonstrate the capability of the facility to investigate hydrogenous substances.

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OBJETIVO: Diferentes métodos são usados para determinar atividade do radioiodo para tratamento de hipertireoidismo (doença de Graves). Alguns não consideram a dose absorvida pela tireóide ou os parâmetros necessários para este cálculo. A relação entre dose absorvida e atividade administrada depende da meia-vida efetiva, da captação do iodo e da massa da tireóide de cada paciente. O objetivo deste trabalho é propor uma metodologia para tratamento individualizado com 131I em pacientes portadores de hipertireoidismo da doença de Graves. MATERIAIS E MÉTODOS: Usou-se um simulador de tireóide-pescoço desenvolvido no Instituto de Radioproteção e Dosimetria contendo solução de 131I, para calibração da gama-câmara e sonda cintilométrica do Serviço de Medicina Nuclear do Hospital Universitário Clementino Fraga Filho da Universidade Federal do Rio de Janeiro. RESULTADOS: O campo de visão colimador-detector apresentou valores compatíveis com o tamanho da glândula para as distâncias de 25 cm (sonda de captação) e 45,8 cm (gama-câmara). Os fatores de calibração (cpm/kBq) foram 39,3 ± 0,78 e 4,3 ± 0,17, respectivamente. O intervalo entre 14 e 30 horas da curva de retenção permite o cálculo de atividade entre dois pontos, para determinação da meia-vida efetiva do iodo na tireóide. CONCLUSÃO: A utilização de equipamentos usualmente disponíveis em serviços de medicina nuclear é viável, tornando esta metodologia simples, eficaz e de baixo custo.

OBJECTIVE: Several methods are utilized for determining the radioiodine activity in the treatment of Graves' disease (hyperthyroidism). Some of this methods do not take into consideration the thyroid absorbed dose or the necessary parameters for this estimation. The association between absorbed dose and administered activity depends on effective half-life, iodine uptake and thyroid mass of each patient. The present study was aimed at developing a methodology for individualized 131I therapy for Graves' disease in patients with hyperthyroidism of the Graves' disease. MATERIALS AND METHODS: A neck-thyroid phantom developed at Instituto de Radioproteção e Dosimetria, containing a standard solution of 131I, was utilized for calibrating the scintillation gamma camera and uptake probe installed in the Department of Nuclear Medicine of the Hospital Universitário Clementino Fraga Filho da Universidade Federal do Rio de Janeiro. RESULTS: The view angle of the collimator/detector assembly presented values compatible with the thyroid gland size for distances of 25 cm (uptake probe) and 45.8 cm (scintillation gamma camera). Calibration factors were 39.3 ± 0.78 and 4.3 ± 0.17 cpm/kBq, respectively. The 14-30-hour interval in the retention curve allows the estimation of activity between two points for determining the effective iodine half-life in the thyroid. CONCLUSION: The utilization of equipment usually available in nuclear medicine clinics is feasible, so this is a simple, effective and low cost methodology.

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