Dosimetric evaluation of individuals to 238U series, 232Th series and 40K radionuclides present in Brazilian ornamental rocks using computational simulation.

Granites are widely used in construction and they may be potential sources of ionizing radiation, due to the presence of radionuclides such as 40Kand decay products from 238Useries and 232Thseries. These radionuclides occur in the minerals constituting the rocks. To evaluate the doses in humans exposed to 40K, and decay products from 238Useries and 232Thseries γ radiation, a room with dimensions of 4.0 × 5.0 × 2.8 m3, with uniformly distributed radiation source on the floor of granitic rocks, was computationally modeled. Adult individuals were represented in the virtual scenario by two virtual anthropomorphic phantoms FASH3 and MASH3, incorporated simultaneously in the software MCNPX 2.7.0. The mean energy deposited on each organ and tissue of FASH3 and MASH3 phantoms was determined using the MCNPX F6 tally (MeV/g/particle), while the photon flux within the room was calculated with the MCNPX F4 tally (MeV/cm2/particle). The organs that obtained the highest conversion coefficients CC[HT](Sv/Gy) were the red bone marrow (0.94), skin (0.90), breast (0.81) and bladder (0.73) for the FASH3; skin (0.89), gonads (0.88), breast (0.79) and bladder (0.70) for the MASH3. The simulated air absorbed dose rates varied between 23.4 (11%) and 25.8 (12%) nGy/h, and the annual dose rates were 0.10 (6%) and 0.11 (6%) mSv/year. These results presented acceptable statistical uncertainties and they are in agreement with the literature. Fluency of photons pointed to the central region of the room floor as the place of greatest exposure. The results showed that the organs closer to the radiation source had the highest deposited energy values. Based on the annual effective dose data obtained, it was possible to note that the values are within the literature. We believe that the methodology used will allow the investigation of any ornamental material that emits natural radiation.

Occupational exposures during abdominal fluoroscopically guided interventional procedures for different patient sizes - A Monte Carlo approach.

In this study we evaluated the occupational exposures during an abdominal fluoroscopically guided interventional radiology procedure. We investigated the relation between the Body Mass Index (BMI), of the patient, and the conversion coefficient values (CC) for a set of dosimetric quantities, used to assess the exposure risks of medical radiation workers. The study was performed using a set of male and female virtual anthropomorphic phantoms, of different body weights and sizes. In addition to these phantoms, a female and a male phantom, named FASH3 and MASH3 (reference virtual anthropomorphic phantoms), were also used to represent the medical radiation workers. The CC values, obtained as a function of the dose area product, were calculated for 87 exposure scenarios. In each exposure scenario, three phantoms, implemented in the MCNPX 2.7.0 code, were simultaneously used. These phantoms were utilized to represent a patient and medical radiation workers. The results showed that increasing the BMI of the patient, adjusted for each patient protocol, the CC values for medical radiation workers decrease. It is important to note that these results were obtained with fixed exposure parameters.

Carbohydrate-enriched diet predispose to anxiety and depression-like behavior after stress in mice.

OBJECTIVES: Obesity is a chronic disease frequently associated with serious co-morbidities, such as diabetes type II, metabolic syndrome, and psychiatric disorders. Little is known, however, regarding the behavioral consequences of modified diet constituents and the propensity to development of stress related disorders. Thus, the aim of this study was to verify whether chronic exposure to a normocaloric/high-carbohydrate diet will modify the animal's behavior after different stressful stimuli. METHODS: BALB/c mice were fed for 12 weeks with a standard chow diet or high refined carbohydrate-containing diet (HC). Following this period, independent groups of animals were exposed to different stress paradigms: 1 - two hours of restraint stress followed by exposure to the Elevated Plus Maze test (EPM) 24 hours later; 2 - The contextual fear conditioning (CFC) test and 3 - the tail suspension test (TST). RESULTS: Despite no change on total body weight, animals fed with HC diet showed increase in serum leptin levels and higher adiposity compared to diet control group. In behavioral tests, animals from HC diet group displayed reduction in the percentage of entries into the open arms of the EPM, evaluated 24 hours after restraint stress, suggesting an anxiogenic-like effect. It is also observed increase in aversive memory in the CFC test and depressive-like behavior in TST. DISCUSSION: Our results suggest that a moderate obesity, induced by high refined carbohydrate diet, may facilitate the development of anxiety and depressive-like behaviors after the stress. The mechanisms responsible for such effects remain to be elucidated.