![]() The minimum change needed to correct for a density error is determined by multiplying or dividing the mAs by 2. The mAs has a direct effect on the amount of radiographic density produced when using a film-screen IR. If the radiograph necessitates an adjustment greater than a factor of 2, the radiographer should multiply or divide the mAs by 4 ( Figure 10-3). As mentioned previously, it may take more than doubling the mAs to correct for a density error. This typically brings the optical densities back within the straight-line portion of the film’s sensitometric curve to best visualize the anatomic area of interest. In general, for repeat radiographs necessitated by density errors, the mAs is adjusted by a factor of 2 therefore a minimum change involves doubling or halving the mAs. The radiographer must decide how much of a change in mAs is needed to correct for the density error. When the radiograph is deemed unacceptable, this means the optical densities lie outside the film’s sensitometric curve’s straight-line portion, and may need to be repeated. When using a film-screen IR, radiographers need to assess the level of density produced on the processed image and determine whether the density is sufficient to visualize the anatomic area of interest. The film characteristic, speed, and chemical processing determine the amount of optical density produced on the image for a given mAs. This relationship between radiation exposure intensity and density is discussed in more detail in Chapter 9. When a film image is too light (insufficient density), a greater increase in mAs may be needed to correct the density, or the mAs may need to be decreased to correct a film image that has excessive density. (From Fauber TL: Radiographic imaging and exposure, ed 3, St Louis, 2009, Mosby.) ![]() C, Increase in density when the mAs is doubled. B, Decreased in density when the mAs is decreased by half. FIGURE 10-2 mAs and Radiographic Density.Ĭhanges in mAs have a direct effect on density. ![]()
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