RESUMO
Purpose.To show the considerations followed for MR-linac in shielding design for the first MR-linac in Mexico following the national clinical necessities.Method.The National Council on Radiation Protection and Measurements (NCRP) 151 recommendations were followed for the shielding design for primary and secondary barriers and the door design. The calculations were made considering the clinical demands in the country, that is, intensity modulated (IMRT) and 3D conformal radiotherapy (3DC-RT) in 80%-20% proportion.Results.The values obtained in the level survey fully comply with the limits established by the national regulatory authority and with those recommended by the International Commission on Radiological Protection (ICRP) for public and occupational exposures.Conclusion.It is remarkable that the workload may increase or that the doses per patient may increase considering occupancy factors, which would allow the introduction of hypofractionated techniques with the same number of patients considered in this work without the need to make modifications in the bunker design.
Assuntos
Proteção Radiológica , Radioterapia Conformacional , Humanos , Aceleradores de Partículas , Radioterapia Conformacional/métodos , Equipamentos de Proteção , Proteção Radiológica/métodosRESUMO
In this work, the seasonal variation of the concentration of radon in soil and its contribution to concentrations inside of a bunker used for the storage and operation of radioactive material was studied. The measurements obtained inside and outside of the installation allowed establish a method for the calculation of the diffusion coefficient for the concrete, variable that directly influences the concentration of radon gas inside of the bunker. With the obtained results of the gamma dose rate and the concentration of radon inside the bunker, the S-index was calculated in order to determine whether the bunker would require some remediation process. The high radon gas concentration rates to which workers are exposed led to study the relative risk of contracting lung cancer (RRLC).
RESUMO
AIMS: This study was aimed to identify yeasts and moulds as well as to detect mycotoxin in corn silages in southern Minas Gerais, Brazil. METHODS AND RESULTS: Corn silages from 36 farms were sampled to analyse dry matter, crude protein, ether extract, ash, neutral detergent fibre, nonfibre carbohydrates and mycotoxins contents, yeasts and moulds population, pH and temperature values. The mycotoxins found in high frequency were aflatoxin in 77·7% of analysed samples, ochratoxin (33·3%) and zearalenone (22·2%). There was no significant correlation between the mycotoxin concentration and the presence of moulds. The pH was negatively correlated with ochratoxin concentration. Aspergillus fumigatus was identified in all silages that presented growth of moulds. Ten different yeast species were identified using the culture-dependent method: Candida diversa, Candida ethanolica, Candida rugosa, Issatchenkia orientalis, Kluyveromyces marxianus, Pichia manshurica, Pichia membranifaciens, Saccharomyces cerevisiae, Trichosporon asahii and Trichosporon japonicum. Another six different yeast species were identified using the culture-independent method. CONCLUSIONS: A high mycotoxin contamination rate (91·6% of the analysed silages) was observed. The results indicated that conventional culturing and PCR-DGGE should be combined to optimally describe the microbiota associated with corn silage. SIGNIFICANCE AND IMPACT OF THE STUDY: This study provides information about the corn silage fermentation dynamics and our findings are relevant to optimization of this silage fermentation.