[en] A polymer-based composite material was developed for use as a yes/no indicator of the high-doses gamma irradiation process. It was prepared with glycerin, gelatin, formaldehyde, clinical gel and copper sulfate pentahydrate (0.1% in relation to the total mass of the composite). Copper sulfate was intended as a chemical indicator of radiation exposure, with mechanisms focused on the processes of interaction with radiation. The formation of copper oxide and sulfur compounds was predicted, which would result in a color change, since CuSO₄.5H₂O confers a blue coloration to the composite. To evaluate the role of copper sulfate in the production of a chemical indicator of radiation exposure, a sample without CuSO₄.5H₂O was also prepared. The samples were irradiated with doses of 50, 80 and 100 kGy of gamma radiation from a Cobalt-60 source, in the Gamma Irradiation Laboratory of the Nuclear Technology Development Center, which has a multipurpose panoramic irradiator. The samples were characterized by Fourier-transform infrared spectroscopy (Ftir), demonstrating their glycerin-based composition. To evaluate the color variation in the irradiated and non-irradiated samples, they were photographed and analyzed using the color catalog of the Adobe Color® application. The sample with CuSO₄.5H₂O showed significant color variation after irradiation, ranging from shades of blue to red/brown. The results demonstrate the potential of polymer composite whit sulfate pentahydrate for use as yes/no indicators of the irradiation process. It encourages future work to evaluate the composite for dosimetry purposes. (author)

[en] Poly(vinylidene fluoride) (Pvdf) is a linear semicrystalline homopolymer, and its polymeric chain is composed by the repetition of CH₂−CF₂ monomers. It is a material with many properties of industrial and biomedical interest has high mechanical performance and high resistance to exposure to ionizing radiation. Bismuth oxide (Bi₂O₃) is an interesting material characterized by X-ray shielding properties. Another very interesting feature is its non-toxicity, which makes it extensively incorporated into various products, such as cosmetics, biomaterials and medicines. In this work, we report an enhanced X-ray shielding effect related to adding Bi₂O₃ nanoparticles in Pvdf matrix. The mass attenuation coefficients measured for nano composite made of Pvdf filled with 50.0 wt % Bi₂O₃, were measured for energy photons in the range of diagnostic X-rays and compared with theoretical value, calculated by using the Nist photon cross section database. Composite characterization was performed with Field-emission electron microscopy (Fe-Sem). The nano composite sample was radio graphed and showed to be visible by the diagnostic technique, evidencing its attenuation property. The results imply that the effectiveness in shielding of X-ray is due to absorption capacity of Bi₂O₃ nanoparticles incorporated in Pvdf, offering efficient protection against X-ray radiation for patients and devices in radiology procedures. It can also be used as an X-ray visible implant material. (author)

[en] Radiation therapy is a crucial technique in the treatment of cancers, often combined with other therapeutic approaches such as chemotherapy and immunotherapy. Advances in stereotactic radiosurgery (SRS), stereotactic body radiotherapy (SBRT) for both cranial and extracranial lesions, intensity-modulated radiation therapy (IMRT), and volumetric modulated arc therapy (VMAT) use relatively small fields, smaller than 4 x 4 cm². Dosimetric analysis for X-ray beams in radiotherapy for small fields presents difficulties due to electronic disequilibrium, source occlusion, high dose gradients, and the average volume of detectors. However, dosimetric analysis for these fields faces challenges due to electronic imbalance, source obstruction, high dose gradients, and reduced detector size. These facts demonstrate the importance of determining and acquiring dosimetric data, understanding the appropriate detectors to be used in each situation, and evaluating the computerized planning system. Errors in planning calculations resulted in higher than planned doses for patients, highlighting the importance of accurate determination of dosimetric data, proper selection of detectors, and rigorous evaluation of computerized planning systems. This work conducts a dosimetric analysis in small fields of the True Beam, Varian manufacturer accelerator from the manufacturer Elekta, using Gafchromic EBT3 radiochromic films, with the use of a solid water phantom to survey dose variations in different field sizes. The results revealed significant variations in dose deposition as a function of field size and among the equipment evaluated. (author)

[en] The understanding of the biogeochemical processes in which trace metals participate in mine regions requires the determination of the different physico-chemical species of the metals present. In the case of uranium extraction mines, the concern is focused on the efficiency of separating other elements present with similar chemical behavior. Added to this are the issues of radioprotection associated with the leaching process and mine acidity. Molybdenum is a trace element present in some uranium-rich regions. The challenge of separating the two elements is presented, reflected in the uranium enrichment process as a subsequent stage in the nuclear fuel cycle. Some separation techniques used have an environmental impact, making these elements available in the environment. In this sense, for this work, simulations were carried out using the PHREEQC program, based on thermodynamic variables and equilibrium constants. The experimental input data were obtained by extracting water in contact with soil from a region of a deactivated uranium mine, followed by analysis by Icp-Ms. The simulations considered different acidity conditions and the presence or absence of organic matter in groundwater. It was possible to distinguish conditions in which the chemical availability of uranium and molybdenum differ, enabling their selective extraction. The simulation showed that the best condition for selective extraction of molybdenum from uranium mine is at acidic ph, since molybdenum forms molybdate (MoO₄^-2) while uranium forms cationic complexes. Under neutral or basic conditions they form similar complexes, confirming the chemical similarity of the elements. (author)