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Diagnostic reference levels (DRLs) are a pivotal strategy to be implemented since pediatric interventional cardiology procedures are increasing. This work aimed to propose an initial set of Brazilian DRLs for pediatric interventional diagnostic and therapeutic (D&T) procedures. A retrospective study was carried out in four Brazilian states, distributed across the three regions of the country. Data were collected from pediatric patients undergoing cardiac interventional procedures (CIPs), including their age and anthropometric characteristics, and at least four parameters (number of images, exposure time, air kerma–area product—PKA, and cumulative air kerma). Data from 279 patients undergoing CIPs were gathered (147 diagnostic and 132 therapeutic procedures). There were no significant differences in exposure time and the number of images between the D&T procedures. A wide range of PKA was observed when the therapeutic procedures were compared to diagnostics for all age groups. There were significant differences between the D&T procedures, whether grouping data by patient weight or age. In terms of cumulative air kerma, it was noted that no value exceeded the level to trigger a monitoring process for patients. This study shows that it is possible to adopt them as the first proposal to establish national DRLs considering pediatric patient groups. [ABSTRACT FROM AUTHOR]

The main sources of radon in the air of dwellings are soil, building materials, and groundwater. This study aimed to determine the exhalation rate of 222Rn from samples made of concrete and cement mortars, as well as to evaluate by means of gamma spectrometry the hazard indexes associated with other radionuclides present in the studied samples of building materials. The results obtained allowed the comparison of the exhalation rate of radon using theoretical calculations based on one-dimensional and three-dimensional models. Measurements of the activity concentration of radon in air was performed by AlphaGuard radon detector. Furthermore, obtained results were compared with the measurements performed inside the concrete test cells. These test cells were built with the aim of simulating a dwelling in small dimensions and to evaluate indoor radon activity associated with concrete. Consequently, the obtained results of radon exhalation rate, in becquerel per meter squared per hour, for the concrete was 2.55 ± 0.03 Bq·h−1·m−2 for the 1D model and 0.461 ±0.008 Bq·h−1·m−2 for the 3D model. The exhalation rate of radon, for the cement mortar was 1.58 ± 0.03 Bq·h−1·m−2 for the 1D model and 0.439 ± 0.011 Bq·h−1·m−2 for the 3D model. The indoor concentration of 222Rn from the test cell was 112 ± 9 Bq/m3. These values were below the limit of 300 Bq/m3 recommended by the International Commission on Radiological Protection (ICRP) and

Background: Appropriate mammary positioning is an important factor in optimizing image quality in mammography (MMG).Purpose: To study the correlation of quality criteria and breast density classification proposed by the American College of Radiology (ACR) and European Guidelines and its influence to achieve a proper positioning, therefore an adequate MMG.Material and Methods: A total of 128 routine MMG examinations were reviewed for the definition of breast composition parenchyma and assessment of several quality criteria proposed by the ACR and European Guidelines to achieve an adequate MMG. Adequate MMG was defined as a difference between the posterior nipple line (PNL), difference of the mediolateral oblique (MLO) and craniocaudal (CC) incidences > 1 cm. The quality criteria were analyzed as a function of correlation coefficient in order to evaluate the individual impact of each factor and analysis of variance (ANOVA) for all criteria. Receiver operating characteristic (ROC) curves were plotted to evaluate the performance of the criteria on each type of parenchyma.Results: Negative correlation of fatty breasts and visibility of the mammary angle, a greater number of skin folds and PNL > 1 cm (r < 0). Dense MMG presented less visibility of the lateral tissue compared with other categories. Area under the curve of ROC analysis revealed values of 53.1% and 54.7% for the right and left breasts, respectively.Conclusion: Several factors influenced in the MMG process, but we find that breast parenchyma has a substantial role in affecting these criteria and therefore a correct position for diagnosis, which could compromise MMG diagnostic performance. [ABSTRACT FROM AUTHOR]

Imaging techniques using protons as incident particles are currently being developed to substitute X-ray computer tomography and nuclear magnetic resonance methods in proton therapy. They deal with relatively thick targets, like the human head or trunk, where protons lose a significant part of their energy, however, they have enough energy to exit the target. The physical quantities important in proton imaging are kinetic energy, angle and coordinates of emerging proton from an absorber material. In recent times, many research groups use the Geant4 toolkit to simulate proton imaging devices. Most of the available publications about validation of Geant4 models are for thin or thick absorbers (Bragg Peak studies), that are not consistent with the contour conditions applied to proton imaging. The main objective of this work is to evaluate the kinetic energy spectrum for protons emerging from homogeneous absorbers slabs comparing it to the experimental results published by Tschalär and Maccabee, in 1970. Different models (standard and detailed) available on Geant4 (version 9.6.p03) are explored taking into account its accuracy and computational performance. This paper presents a validation for protons with incident kinetic energies of 19.68 MeV and 49.10 MeV. The validation results from the emerging protons kinetic energy spectra show that: (i) there are differences between the reference data and the data produced by different processes evoked for transportation and (ii) the validation energies are sensitive to sub-shell processes. [ABSTRACT FROM PUBLISHER]

Abstract Portland cement is the main ingredient of concrete and various types of finishing materials. It is considered as the main and most consumed building material in the world, which is used for all type of construction including residential and commercial buildings, dwellings, offices, and industrial facilities. Portland cement is made from the chemical composition of major oxides, such as CaO, SiO 2 , Al 2 O 3 , and Fe 2 O 3 , and minor oxides, which include MgO, SO 3 together with alkali oxides (K 2 O and Na 2 O) and other compounds such as P 2 O 5 , TiO 2 , MnO 3 , among others. Being produced from different type of natural raw materials, such as limestone, chalk, marl, clays, slags and shale among other, the manufacturing of Portland cement involves the crushing rocks, their mixture with different ingredients such as iron ore or/and fly ash, grounding, homogenizing of this mixture, and then its calcination and fusion at a temperature about 1450 °C. As result of such industrial process the Portland cement could contain rather significant quantity of natural radionuclides such as 226Ra, 232Th and 40K. The main purpose of present study was to characterize and quantify the concentration levels of 226Ra, 232Th and 40K in Portland cement, gypsum and phosphogypsum mortar samples from Brazil using gamma spectrometry. The radiological risk of studied building materials was evaluated by measurements of activity concentration of 222Rn exhaled by these materials into the air and calculating the values of the emanation coefficient (f), the radium equivalent activity (Ra eq), absorbed gamma dose rate (D in), the annual effective dose (E in), the alpha hazard index (I α), the gamma hazard index (I γ), as well as external hazard index (H ex) and the internal hazard index (H in). Obtained values of hazard indexes were found below the recommended limits. Highlights • Radon activity in air related to Portland cement, natural gypsum and phosphogypsum was measured. • The index of activity concentration of Portland cement, natural gypsum and phosphogypsum was evaluated. • The radium equivalent activity of Portland cement, natural gypsum and phosphogypsum was evaluated. • The hazard indexes of Portland cement, natural gypsum and phosphogypsum were evaluated. [ABSTRACT FROM AUTHOR]

The present work describes the results of systematic measurements of radon ( 222Rn) in residential environments and workplaces in the Metropolitan Region of Curitiba (Paraná State, Brazil) during the period 2004-2012. For radon in air activity measurements, polycarbonate Track Etch Detectors CR-39, mounted in diffusion chambers protected by borosilicate glass fiber filters, were used. After being exposed in air, the CR-39 detectors were submitted to a chemical etching in a 6.25 M NaOH solution at 70 °C for 14 h. The alpha particle tracks were identified and manually counted with an optical microscope, and with the results of previously performed calibrations, the indoor activity concentration of 222 Rn was calculated. The calibration of CR-39 and the alpha particle tracks chemical development procedures were performed in collaboration the National Institute of Radiological Sciences (NIRS, Japan). The major part of indoor 222 Rn concentration in residences was found to be below 100 Bq/m 3 . In the case of working places, all measurements of 222 Rn concentrations were below 100 Bq/m 3 . These values are considered within the limits set by international regulatory agencies, such as the US EPA and ICRP, which adopt up to 148 and 300 Bq/m 3 as upper values for the reference levels for radon gas activity in dwellings, respectively. The latest value of 300 Bq/m 3 for radon activity in air is proposed by ICRP considering the upper value for the individual dose reference level for radon exposure of 10 mSv/yr. [ABSTRACT FROM AUTHOR]

Considering that 222Rn activity concentration in well water can contribute to indoor radon concentration levels, which represent a radiation risk for the public, measurements of 226Ra and 222Rn activity in well water in Curitiba, Paraná State, Brazil were performed. Each water sample was submitted to four measurements for radon concentration over an interval of three days. After two months, the same samples were submitted again to 222Rn concentration measurements with the objective of indirectly evaluating the amount of 226Ra in them. The 222Rn concentration measurements were performed with an AlphaGUARD radon monitor (SAPHYMO), and the 226Ra concentration was evaluated with the decay curves of 222Rn. Within a few hours after extraction, about 70% of water samples from monitored wells presented 222Rn concentration values above the limit of 11.1 Bq/L recommended by the EPA of the United States. The obtained activity values varied between 1.6 Bq/L and 215 Bq/L for radon concentration, and radium concentrations deviated within an interval of 0.50 Bq/L and 6.8 Bq/L. The results reveal that the biggest part of 222Rn found in water samples originated not from soluble 226Ra compounds but from gas exhalation by the soil and rocks adjacent to the well. The results point to the necessity of mitigation procedure development for better control of global alpha radioactivity in drinking water. [ABSTRACT FROM AUTHOR]