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Concerning noise within a radio graphic image: a. The level of noise decreases with increased patient dose b. The signal-to-noise ratio (SNR) increases with increased patient dose c. When imaging tissues with low inherent contrast (such as in mammography), the effect of noise is less significant d. When imaging tissues with high inherent contrast, the effect of noise is less significant e. The effect of noise can be reduced by using a film with high gamma |
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Answer» a. False. Noise will increase as a proportion of the number of photons (n) that are detected in the image (as noise = √n). b. True. Although the amount of noise will increase with increasing patient dose, the actual SNR increases and so improves image quality. c. False. Noise is more significant. Differentiating between the nature of soft-tissue structures is more important when there is less inherent contrast within the tissues being imaged. Therefore, noise will prevent this differentiation. d. True. e. False. The higher film gamma produces more radio graphic contrast within the film for the same exposure, but also has the same effect on the noise, which is displayed in the image. |
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