Neste artigo apresentamos as bases da Física das radiações, as fontes naturais e artificiais, os efeitos biológicos, a proteção radiológica. Examinamos também a sequência de eventos que resultou no acidente de Goiânia com uma fonte de césio-137 de um equipamento de radioterapia abandonado e suas terríveis consequências.

This study presents a comparison of the X-ray transmission through microsized and nanosized materials. For this purpose CuO nanoparticles, with 13.4 nm average grain size, and CuO microparticles, with a mean particle size of 56 μm, were incorporated separately to beeswax in a concentration of 5%. Results show that the transmission through the above material plates with microsized and nanosized CuO was almost the same for X-ray beams generated at 60 and 102 kV tube voltages. However, for the radiation beams generated at 26 and 30 kV tube voltages the X-rays are more attenuated by the nanostructured CuO plates by a factor of at least 14%. Results suggest that the difference in the low energy range may be due to the higher number of particles/gram in the plates designed with CuO nanoparticles and due to the grain size effect on the X-ray transmission.

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