Assessment of radiological hazards from radioactivity natural of cement used in Dwellings in Rio de Janeiro, Brazil.

Brazil is the fourth largest cement consumer in the world and the largest producer in Latin America, around 1.3% of global production. The main inputs in the manufacture of cement are limestone and clay. Few studies have been carried out in the country on the risk of these materials used in civil construction. Therefore, the objective of this present work is to evaluate the radiological danger that they can present to society. Gamma spectrometry analysis on 16 samples of different brands of cement used as construction material in Rio de Janeiro (Brazil) was performed in this study, using an HPGe detector and the Genie 2000 data acquisition software. Samples were set to count for an accumulation time of 14,400 s (4 h) and all measurements were corrected to eliminate background and backscattering. Activity concentrations are determined for 226Ra was from (41.2 ± 1.6 to 174.9 ± 3.9) Bq kg-1, 232Th was from (15.7 ± 0.5 to 43.1 ± 0.7) Bq kg-1 and 40K was from (82.6 ± 7.2 to 254 ± 17) Bq kg-1. To assess radiological health risks: mean values of Radium Activity Equivalent 150.0 ± 3.4 Bq kg-1, Annual Gonadal Dose Equivalent 468 ± 11 µSv year-1 and Lifetime Excess Cancer Risk (ELCR) 2.42 ± 0.06 were calculated. Total Absorbed Dose Rates ranged from 72.2 ± 1.7 to 225.1 ± 5.2 nGy h-1. The damage to collective health was also estimated from the annual effective dose rates with an estimated total cost of damage to health of US$ 130 million. Values are generally within global limits reported by UNSCEAR.

An assessment of committed effective dose and lifetime cancer risk due to the ingestion of infant milk.

Infant milk is a manufactured food designed for feeding babies and infants under 12 months of age. This product is indicated when, for some reason, the baby can not be fed by breast milk. It is used in case of intolerance to milk from farmed animals and is widely used for the nutrition of newborns in artificial lactation, in place of breastfeeding. It can be used as a complete or partial substitute for human milk. In the current study, the committed effective dose and lifetime cancer risk due to ingestion of 4 K, 226Ra, and 228Ra were estimated using activity concentration obtained from high-resolution gamma spectrometry. Consumption data and dose coefficients were obtained from Brazilian Institute of Geography and Statistics and data published by ICRP 119. Infant milk and water samples were collected in the Rio de Janeiro trade, placed in a polystyrene container, and then sealed to reach the secular radioactive equilibrium condition (at least 45 days). The samples were analyzed by gamma spectrometry using a High Purity Germanium (HPGE). Detection efficiency for each sample was obtained with LabSOCS software. For infant milk samples, the highest values of activity concentrations were (242 ± 9) Bq.kg-1 for 4 K, (5 ± 1) Bq.kg-1 for 228Ra and presented values below the detection limit for 226Ra. The higher values obtained for water samples were (10 ± 1) Bq.l-1, (5 ± 1) Bq.l-1, (5.3 ± 0.1) Bq.l-1 for 4 K, 226Ra and 228Ra, respectively. These values of committed effective dose are below the values stipulated by UNSCEAR (290 µSv.y-1) and by the ICRP (1 mSv.y-1). The values obtained for lifetime cancer risk are considered negligible, once they are below the limit considered for taking action (10-4). It can be concluded that the values calculated do not present a significant risk regarding the intake of infant milk in the first two years of the child's life.

137Cs activity concentration in soil of Alagoas State, Brazil.

Cesium 137 is present in worldwide. To evaluate its deposition in the Brazilian state of Alagoas a total of 41 samples were collected by the Geological Survey of Brazil, then processed and analyzed by gamma-ray spectrometry with hyperpure germanium detectors. The activity concentration varied from (0.3 ± 0.1) Bq/kg to (1.1 ± 0.4) Bq/kg. The present study shows that the Borborema Plateau acts as a natural barrier to rainfall, favoring the deposition of 137Cs on the local soil.

SPECT performance evaluation on image of Yttrium 90 - Bremsstrahlung using Monte Carlo simulation.

Yttrium-90 (90Y) is one of the most widely used radionuclides in Nuclear Medicine practice. However, characteristic energy of this beta emitter constitutes a difficulty for dose planning using SPECT imaging. This work aimed to study bremsstrahlung X-rays effects produced by 90Y beta particles during SPECT image acquisition using Monte Carlo code MCNPX. Several simulations were carried out to evaluate different aspects that could affect SPECT image quality, such as: collimator type, source-collimator distance and composition of each interacting material. Two configurations of 90Y sources were simulated: a point source in several spheres of different materials (soft tissue, water, articular cartilage, and bone) and dimensions with radius ranging from 1 to 20 mm; and a uniformly distributed source in a Lucite cylindrical phantom filled with water. It was evaluated the bremsstrahlung photon emission generated inside different materials; for this was considered the number photons that passing through every different sphere's surface for each radii and material. In case of cylindrical phantom filled with water, in order to obtain the energy deposited over NaI (Tl) crystal detector; there was considered Median Energy General Purpose (MEGP) and Low Energy High Resolution (LEHR) collimators. Moreover, using TMESH routine available in the MCNPX Monte Carlo code, energy distribution images according to the collimator type and the source-collimator distance were obtained. The simulation was validated by comparing with the spectral distribution of the 90Y bremsstrahlung X-rays obtained experimentally from an acrylic cylindrical phantom. Results corroborated the importance of Monte Carlo simulation method to evaluate a performance of SPECT image acquisition with 90Y. The best resolution was obtained with MEGP collimator independent of source-collimator distance.

Radiological evaluation of Ra-226, Ra-228 and K-40 in tea samples: A comparative study of effective dose and cancer risk.

Activity concentrations of tea samples were determined using high resolution gamma spectrometry.The values ranged from (421.00 ± 17.00) to (732.00 ± 30.00) Bq.kg -1 for K-40 and from (3.00 ± 0.80) to (27.00 ± 3.00) Bq.kg-1 for Ra-228. The values for Ra-226 were below 27.00 Bq.kg-1. The committed effective dose was estimated at 4.74-78.89 µSv.y-1 for adults and 13.55-445.84 µSv.y-1 for children. The cancer risk was higher for females. However, results showed that the tea consumption do not represent a radiological health risk to the population.

Individual dose planning in radiosynoviorthesis treatment: Step by step.

Radiosynoviorthesis (RSO) is a minimally invasive treatment aiming for the necrosis of the pannus tissue by the use of radionuclide. The method suggested here starts with the segmentation of the joint effusion, synovial thickness, and area of the synovial membrane using the 3D Slicer software. The last step is the estimated value of the activity to be injected without considering the leakage of the radiopharmaceutical into the articular cavity. It includes the S-values obtained by Monte Carlo simulation coupled with the calculated therapeutic distance (ST90).