Hasil untuk "Radioactivity and radioactive substances"

Florencia Agustina Perez Gutierrez, Francieli Bernardo Ribeiro, Maria Eduarda Vieira Cidral et al.

Estimating the radiation doses received from the growing demand for Computed Tomography (CT) scans helps to optimize protocols and image quality. With the aim of evaluating medical exposures in total abdomen protocols, this study extracted CT data from the Santa Catarina Telehealth and Telemedicine System (STT-SC), which was entered into the NCICT® 3.0 software to estimate the effective doses and organ doses for the examinations evaluated. The presentation of the main data obtained through statistical and descriptive analysis allows comparison with other studies. The average effective dose was 7.50 mSv for female patients (n=57) and 8.03 mSv for male patients (n=43). The spleen received the highest dose in the abdominal region, with an average of 10.99 (±4.24) mGy for men and 9.89 (±4.75) mGy for women. In conclusion, this study found variations in organ doses between male and female patients, with the lungs receiving the highest dose in women and the liver in men. These results support the need to review and adapt CT examination protocols to optimize radiation exposure, and the results presented in this study will allow for comparative evaluation with data that may be collected later as the study continues.

Hugo Leonardo Silva, Tarcísio Campos, Noil Cussiol

According to national and international standards, some groups and subgroups of Healthcare Services Waste (RSS) must undergo some type of treatment to reduce or eliminate the pathogen load before final disposal, to avoid harm to human health and the environment. The pathogens present in the infecting HCW can be effectively inactivated by radiation, providing a uniform minimum dose recommended over the entire volume of the HCW. The analysis of radiation transport in HCW containment containers require determination of the radiation dose coefficients, called: KERMA-fluence for photons and the Mass Stopping Power for electrons; to verify whether the absorbed dose in the container was sufficient for pathogenic inactivation. The chemical compositions of segregated HCW, as well as non-segregated HCW, were evaluated by previous analytical studies by means of segregation of hospital waste. The mass energy absorption coefficients for the chemical composition of HCW at various energies of photon beams and the related density of the RSS supported the calculations of the Radiation Dose Coefficients, KERMA-fluence, and the Mass Stopping Power of electrons for HCW. The results for HCW were compared with equivalent water parameters. The water material does not represent a good substitute for HCW in the dosimetric processes of calibration of exposures to X-ray radiation and electrons in most of the energy spectrum analyzed. There are significant differences between the KERMA-fluence and Mass Stopping Power coefficients of the HCW in relation to water, inducing a very different energy fluency in the RSS in relation to water. A better radiological characterization of HCW for the purpose of sterilization by ionizing radiation was achieved. The Radiation Dose coefficients in the analyzed energy fluence range proved to be useful in the predictions of absorbed dose at exposures of non-standard volumes of RSS.

Janete de L. Stanziani Gibba, Maria J. A. Oliveira, Larissa Otubo et al.

Effective conservation strategies for leather artifacts and art objects are essential for preserving cultural heritage, particularly given the inherent vulnerability of the material to biodegradation, as leather, an organic material, is especially susceptible to this process. Gamma radiation has emerged as a promising method for the disinfestation and disinfection of cultural heritage objects and archival materials. This study aimed to advance the understanding of gamma radiation as a conservation technique for vegetable-tanned snake and chrome-tanned bovine leather, specifically focusing on its effects on chromaticity, surface topology, fiber structure and thermal behavior. Gamma radiation was applied at controlled doses of 1 and 3 kGy, and its impact on the morphology of the leather was assessed using colorimetry within the CIELAB color space and field emission gun scanning electron microscopy (FEGSEM). The findings indicated that gamma radiation at these doses induced minimal alterations in the morphological properties of the leather. The color differences for irradiated and non-irradiated samples were negligible, with total color differences (ΔE) remaining within acceptable limits (ΔE < 3). Moreover, FEGSEM analysis demonstrated that the fiber structure and surface morphology were not significantly compromised by the irradiation process. Thermogravimetric analyses showed similar thermal decomposition between non-irradiated and irradiated samples for both bovine and snake leather, with detailed data analysis indicating thermal stability. The results supported the efficiency of gamma radiation as a conservation technique for both bovine and snake leather artifacts, preserving their aesthetic and structural integrity.

Franklin Cândido Costa, Antônio Belchior Júnior, Walmir Maximo Torres et al.

Among the most critical accidents for the IEA-R1, there is the Loss of Flow Accident (LOFA) in which a sudden and abrupt stop of the primary pump causes the loss of flow. Traditionally, this kind of accident is analyzed by thermal-hydraulic system codes. However, they can overestimate the fluid and fuel temperature along the transient by up to 20%. Moreover, thermal-hydraulic system codes can face difficulties to capture three-dimension phenomenon, such as the natural convection. Meanwhile, Computational Fluid Dynamics (CFD) analysis has shown good results when analyzing open-pool research reactor accidents even dealing with flow inversion. This work presents a thermal-hydraulic analysis of a Slow Loss of Flow Accident (SLOFA) in the IEA-R1 using the RELAP5 code and the commercial CFD code Ansys CFX®. The objective is to combine the advantages of both approaches. The system code was used to find the transient boundary conditions for a CFD model. The CFD software solved the detailed flow pattern in a quarter of a fuel channel. The numerical results showed good agreement with the benchmark data. The peak temperatures were overestimated in only 1.8 °C in the fluid and 3 °C in the cladding. 

Maria Paula de Oliveira Goes, Cibele Bugno Zamboni, Maria Gabriela Miquelino Benedito et al.

Iron Deficiency Anemia is a significant global issue, particularly affecting pregnant women and young children. Traditional methods of diagnosing iron-deficiency anemia generally require extensive and costly laboratory procedures. This study explores the feasibility of using portable Energy Dispersive X-ray Fluorescence (EDXRF) technology for assessing iron concentration in whole blood samples from donors diagnosed with iron deficiency anemia. The results indicated a marked decrease in iron levels in the blood samples from patients with anemia compared to the control group. The EDXRF technique demonstrated several advantages, including simplicity in sample collection, rapid measurement time, and low cost. This method is particularly promising for use in situations where biological material is limited, such as in pediatric practices for newborns. The study concludes that portable EDXRF technology is an effective and efficient tool for diagnosing iron deficiency anemia, potentially improving diagnostic accessibility and outcomes.

Igor Fernando Modesto Garcia, Jeovana Santos Ferreira, Eric Matos Macedo et al.

For the new metrological challenges of an increasingly digitized world, several countries are developing applications and infrastructure for Digital Calibration Certificates – DCC, researching the comparability of real and virtual measurements. Objective: to map the processes and risks related to the digital transformation of X-rays air kerma calibration. The Failure Mode and Effect Analysis - FMEA was used to quantify risks and is widely used in the aviation and automotive industry due to its reliability. The results presented a conceptual model for calibrating ionizing radiation quantities in the framework of new technologies and calibration 4.0 and comparing processes and risks. The conceptual model of calibration 4.0 comprises three main parts: a transmitter, the 4.0 communication network, and a receiver. Intelligent devices with configurations enable calibration data transfers by radio-frequency messaging in all these parts. Comparing risks in contemporary and calibration 4.0 processes, a slight reduction in the total risk can be observed. But new risks are unique to the 4.0 model, all with maximum severity, and how to mitigate them is still unknown. It is also possible to estimate that artificial intelligence and automation can significantly reduce measurement risks, identification, and error in the analysis and use of calibration certificates.

S. V. Fesenko, P. V. Prudnikov, E. S. Emlyutina et al.

The purpose of the study was to analyze the regularities of 137Cs concentrations in grain, potatoes and vegetables in the areas affected the Chernobyl accident. The data describing the countermeasures in the south-western districts of the Bryansk region are given. The system of radiological monitoring of plant products is described and the relevant data are presented. Dynamics of concentrations both in grain and in potatoes and vegetables had a pronounced heterogeneous character. Reduction of 137Cs concentration in crop production (grain, potato, and vegetables) was determined by the dynamics of agrochemical countermeasures in the contaminated areas, sorption of 137Cs in soil and radioactive decay. It has been revealed that effective halflives of 137Cs in the above products during intensive implementation of rehabilitation measures (1987-1990) varied within the range from 0,7 up to 1,3 years. Subsequently, in 1991-2011, the decrease of contamination of products slowed down, and in some areas with intensive application of protective measures a certain increase of 137Cs content in products was noted. Effective half-lives during that period ranged 10.5-29 years depending on the peculiarities of application of countermeasures and soil characteristics. The pattern of the 137Cs concentrations in the grain produced in different districts from 2011 to 2021 also differed depending on the history of the countermeasures’ application in those districts in the previous periods. The estimation of the effective half-life, equal to 18.2 years, for predicting the reduction of plant product contamination in the long term after the Chernobyl accident has been suggested.

L. A. Chipiga, E. R. Ladanova, A. V. Vodovatov et al.

The federal forms of statistical reporting (3-DOZ form, form No. 30 of the Ministry of Health of the Russian Federation and radiation-hygienic passports of the subjects of the Russian Federation for 2015–2020) were analyzed in order to estimate the current status of nuclear medicine and assess the perspective and developing proposals for improving the national system of radiation protection in nuclear medicine. Over the past six years, the number of radionuclide examinations in the Russian Federation has been at the same level: on average 530 thousand per year. In 2020 the number of examinations decreased that was caused by the epidemic of coronavirus infection. The largest number of examinations in 2015-2020 were performed in Moscow (21%) and St. Petersburg (11%). Federal medical centers equipped with high-tech equipment are located in these cities, and patients from different regions are examined in these centers. The examination of bone is the most common examination in Russia: 40% from all of nuclear medicine examination; there is a moderate increase of that examinations. There is a high number of renal examinations (17%). The next most frequent are examinations of myocardium, thyroid, liver and lungs; the number of these examinations are decrease. Due to the development of modern diagnostic technologies, installation of new positron emission tomography departments and replacement of the old equipment with the new one (decrease in the number of renographs and increase the number of positron emission tomographs), the number of “other” examinations are increased with a factor of 3.7 since 2015 but the number of “functional” examinations is decreased. About two thousand studies per year were examined on a scanner (renograph, gamma camera, single-photon emission tomography), and about 0.6 thousand hybrid imaging examinations per year were performed on a single-photon emission tomography combined with computed tomography. The annual collective dose of radionuclide diagnosis in the country has increased from 1.2 to 3.7 thousand man-Sv since 2015. The main contribution to the collective dose in Russia was associated with “other” examinations, which include hybrid imaging and whole body positron emission tomography: 55% (39% in St. Petersburg, 60% in Moscow). Due to the limitations and heterogeneous content of the federal forms of statistical reporting it is difficult to assess the current state of nuclear medicine in the Russian Federation. The authors of the study were updated of the data collection system in the radionuclide diagnosis in 3-DOZ forms; it is under approval. For detailed and reliable assessment of the nuclear medicine in the country, it is necessary to conduct a separate survey to determine the types of nuclear medicine examinations, the gender and age profile of patients and patient doses. That survey should be conducted in St. Petersburg or Moscow, as model subjects of the Russian Federation.

René Rojas Rocca, Caroline Paschoal Fernandes

Several doped materials are being studied for dosimetric application, but when some dopant is used with the aim to increase the sensibility, some of these can increases the hygroscopic properties of the sample, which is not suitable for dosimetry. If the material absorbs water during the storage period, it may change their luminescent properties, reducing or completely erasing the signal produced by ionizing radiation. Unlike thermoluminescence, OSL measurements do not need high temperature to read the signal, however, sometimes some assisted temperature or preheating is required. In this work is presented a new low-cost option for performing OSL measurements, even with preheating up to 160 oC. It was tested a transparent enamel for sticking the luminescent powdered samples on aluminum disc and also covering the samples with the enamel avoiding in this way the absorption of humidity from the environment, even the signal decreases, the reproducibility and fading do not depend of their hygroscopic properties.

Raphael Francisco Gomes Santos, Luis Eduardo Barreira Brandão, Alessandro Mariano Domingues et al.

The use of radiotracers of product flow ducts from the oil and gas industry allows checking of installed flow meters and knowledge of the flow profile within the duct. The time transient method is older for the flow media and gauging of the flowmeters and lower permanence of the radioactive magazine at two different points. For the oil and gas industry, it is important that there is an average rate of 0.7%, so that this value is reached by a level of necessary care. One of the points is a correct detector / duct geometry at the two measurement points because the quality of the contents depends on the passage across a straight section of the radioactive duct. The present work has the purpose of analyzing the collimation effect of the detector signal during radiotracer during flow in a steel duct using  Au198 as the radiotracer. The analysis was carried out using computer simulation using the computational code Microshield, simulating the entire face detector / shielding / collimation system of the NaI detector 2x2" and the fluid being used in conjunction with the system Glycerol in regime of turbulent flow. The study is found in the same way as the radio of the detector in the same distance of the radio reserve from the radio in the entrance to the standard of the ANP.

Maria Auxiliadora Fortini Veloso, Wallen Ferreira De Souza

The present work concerns the use of 1995 CHF table for uniformly heated round tubes, developed jointly by Canadian and Russian researchers, for the prediction of critical heat flux in rod bundles geometries. Comparisons between measured and calculated critical heat fluxes indicate that this table can be applied to rod bundles provided that a suitable correction factor is employed. The tolerance limits associated with the departure from nucleate boiling ratio (DNBR) are evaluated by using statistical analysis.

João Pedro Oliveira Flores, Paulo Sérgio Cardoso Silva, Mauro Silva Dias et al.

The short irradiation facility of the IEA-R1 nuclear research reactor at IPEN, São Paulo,  Brazil, has been used for short irradiation of samples for the purpose of determining the concentration of elements of these samples through the use of the instrumental neutron activation analysis technique. With the aim of implementing the k0-NAA method at the Neutron Activation Analysis Laboratory (LAN), the reactor parameters a and f were obtained using the bare triple method. In this method, a set of three neutron flux monitors were irradiated without Cd-cover. The efficiency curve of the gamma-ray spectrometer used was determined by measuring calibrated radioactive sources at the commonly used counting geometries. The results for the parameters a and f were respectively 0.0384±0.0016 and 35.67±0.26. This value of f shows that the neutrons in the irradiation position are well thermalized.The variation of these parameters was studied with time and the reproducibility was verified.

OSANA DINIZ FERREIRA, RAQUEL CORDEIRO De OLIVEIRA, FABIANA FARIAS De LIMA GUIMARÃES et al.

O Gengibre (Zingiber officinale roscoe) é conhecido mundialmente por suas propriedades medicinais devido à presença de numerosos compostos bioativos com potenciais terapêuticos dos tipos hepatoprotetor, antihemorrágico, anti-inflamatório, anticancerígeno, antibacteriano/fungicida e antioxidante [1]. Dos compostos encontrados em abundância na planta, destaca-se o gingerol, constituinte não volátil responsável por maior parte das ações farmacológicas já descritas até hoje. Na modalidade SPECT (Tomografia Computadorizada por Emissão de Fóton Único) para aquisição de imagens, as hemácias radiomarcadas com 99mTc assumem um papel importante no diagnóstico utilizando o pool sanguíneo, devido à abundante concentração celular e capacidade do complexo de se difundir no espaço intravascular de forma relativamente lenta, permitindo a formação de imagens de alta resolução [9]. Contudo, pesquisas relatam diminuição na capacidade de marcação das populações celulares de interesse, através do 99mTc, após interação do radiofármaco com extratos medicinais em diferentes concentrações, levando à alterações na farmacocinética e farmacodinâmica do composto, reduzindo assim, a resposta farmacológica.Dessa forma, o objetivo desse trabalho é estudar a marcação de hemácias com o 99mTc, avaliando os efeitos de diferentes concentrações do extrato etanólico do gengibre na captação do radionuclídeo pelas células, estabelecendo um modelo do tipo experimental in vitro. Os resultados revelaram que  a partir  das concentrações de 30, 50 e 100mg/ml do extrato do gengibre tem-se uma redução da ligação do 99mTc nas hemácias e um aumento significativo da captação do radionuclídeo pela fração plasmática (plasma).

Daniel Perez Vieira, Andrés Jimenez Galisteo Jr., Heitor Franco de Andrade Jr.

Reduction of nitric oxide (NO) production is related to increased survival in some models of infection and ionizing radiation (IR) exposure. The work used lethally irradiated (60Co, 8Gy) C57Bl6j mice, treated or not with aminoguanidine (AG), an inhibitor of an isoform of nitric oxide synthase (iNOS). Also tested iNOS-/- knockout mice and a distinct group treated intraperitoneally with synthetic CXCL12, a homing chemokine related to hematopoietic reconstitution after IR exposures. Aminoguanidine treatment lead to an overshoot of proliferation of hematopoietic CD34+ cells in bone marrows (2nd day after IR) and spleens (2nd to 4th day after IR) of irradiated mice, showing a compensative response of these organs against deleterious effects of radiation. CXCL12 mRNA production was increased in spleens of AG-treated mice at 2nd day after IR, but not in other periods neither in bone marrows. CXCL12 administration did not alter CD34+ counts but seemed to keep circulating platelet counts in levels comparable to controls. Thus, CXCL12 and AG administration could help on bone marrow repopulation after critically exposed individuals.

Flávia Del Claro, Sergei Anatolyevich Paschuk, Janine Nicolosi Corrêa et al.

Naturally occurring radionuclides such as radon (222Rn), its decay products and other elements from the radioactive series of uranium (238U and 235U) and thorium (232Th) are an important source of human exposure to natural radioactivity. The worldwide evaluation of health radiobiological effects and risks from population exposure to natural radionuclides is a growing concern. About 50% of personal radiation annual dose is related to radionuclides such as radon (222Rn), thoron (220Rn), radium (226Ra), thorium (232Th) and potassium (40K), which are present in modern materials commonly used in construction of dwellings and buildings. The radioactivity of marbles and granites is of big concern since under certain conditions the radioactivity levels of these materials can be hazardous to the population and require the implementation of mitigation procedures. Present survey of the 222Rn and 220Rn activity concentration liberated in the air was performed using commercialized Brazilian granite rocks at national market as well as exported to other countries. The 222Rn and 220Rn measurements were performed using the AlphaGUARD instant monitor and RAD7 detector, respectively. This study was performed at the Applied Nuclear Physics Laboratory of the Federal University of Technology – Paraná (UTFPR). Obtained results of radon concentration activity in air exhaled studied samples of granites varied from 3±1 Bq/m3 to 2087±19 Bq/m3, which shows that some samples of granitic rocks represent rather elevated health risk the population.

Paula Rocha Pessanha, Pedro Pacheco de Queiroz Filho, Denison de Souza Santos

For the dosimetric evaluation of extremities and crystalline of workers inserted in Positron Emission Tomography procedures using the 18F-FDG radiopharmaceutical, a geometric phantom of the forearm and hand with the geometric phantom ADAM was implemented in Monte Carlo Geant4 code. Equivalent Dose values were obtained in 45 different points - between dominant, non-dominant and crystalline hands - for radiopharmaceutical administration procedure, with the use of injection syringe shielding. The data obtained through the simulation were analyzed according to dose limits established by the CNEN standard NN-3.01 of 2014.

PRYCYLLA GOMES CREAZOLLA, FELLIPE SOUZA DA SILVA, Alexander Camargo et al.

As fontes radioisotópicas de nêutrons permitem a produção de campos de referência para calibração de dispositivos de medição de nêutrons para fins de radioproteção e análises. Quando a taxa de emissão dessas fontes se dá de forma isotrópica, não é necessária nenhuma correção. Entretanto, variações no material da cápsula da fonte e variações na concentração do material emissor produzem diferenças em sua taxa de emissão de nêutrons em relação ao eixo axial da fonte, este efeito é denominado anisotropia. Sendo assim, é necessário considerar o fator anisotrópico relativo às fontes de nêutrons para que seja realizada uma calibração adequada dos instrumentos e dispositivos sensíveis aos campos de nêutrons.

X. Donadeu, C. Ashworth

G. N. Kaydanovskiy, E. N. Pirogova

The paper analyses the main sources of measurement errors of individual doses in personnel performed within the thermoluminescence technique and gives recommendations to minimize these errors. The reasons that reduce reliability of effective dose assessments derived from measured values of personal dose equivalent are imperfections of guidance documents. Changes to the Guidelines «Organization and implementation of individual dosimetric control. Staff of health institutions» are justified.

Jerusa Finatto, Ana Paula Pastre Froner, Juliana Pimentel et al.

Computed tomography is considered a high radiation dose modality, and therefore establishment of diagnostic reference levels is highly recommended. These levels are expected not to be exceeded for standard procedures, when good practice is applied. Most CT scanners display a dose index, CTDIvol. For pediatric studies, this dose index is measured using a standard phantom and an ionization chamber, and does not represent patient dose, but a reference measurement. The objective of this study was to investigate the CTDIvol dose descriptor in head CT scans of a sample of pediatric patients, comparing them with the DRL presented in the literature. Data of head CT without contrast of 40 pediatric patients were retrospectively collected. The acquisition parameters of each examination were extracted from DICOM header and analyzed to assess the protocols typically used by technicians. The mean values of CTDIvol of each group were compared with the DRL values from literature. The measurement of accuracy indicated a difference of 11,6% with the CTDIvol registered by the scan, which can be explained by six different protocols used by technicians for the same exam. The variation is specially critic for the youngers than 1 year. Some children were submitted to a protocol with 50% higher dose than others. This group has 4% higher mean CTDIvol than DRL in literature, while other groups have lower values. The results show the role of medical physicist, optimizing clinical protocols to guarantee the maximum image quality with minimum dose.