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Concerning grids: a. They may be focused or unfocused b. They may produce artefacts on the final image c. Stationary grids are commonly employed d. The higher the grid factor, the greater the exposure required to produce a film of the same radio graphic density e. The effect of grids on scatter depends mainly on the grid ratio |
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Answer» a. True. This describes the orientation of the lead strips in relation to the path of the X-ray beam. As X-rays are divergent from their source, focused grids have their strips tilted to allow more of the primary radiation to pass through the grid. b. True. Shadows from the lead strips may be superimposed on the final image. c. False. As described above, shadows may be projected onto the final image. This effect may be reduced by using moving grids, which oscillate during the exposure. These are more commonly used than stationary grids. d. True. This is a ratio of the exposures required with and without a grid. e. True. The grid ratio describes the effect of the grid in reducing scatter. The higher the grid ratio, the more scatter will be removed. |
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