Week 6 mAs 40 - Radiographic Image Quality Image visibility...

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1 Radiographic Image Quality Image visibility or the Photographic Properties Density: The overall blackness of the image. Contrast: the difference between adjacent densities on a radiograph.
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2 Density If the image is too dark, it has too much density. If the image is too light, it lacks density. X-rays are like toast. If it is dark it is over cooked or overexposed . If it is light, it is underexposed.
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3 Contrast The difference between density of adjacent structures is contrast. Contrast is controlled by the energy of the beam. High contrast is too black and white. Low contrast is too gray.
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4 Contrast and Density Contrast and Density are controlled by the exposure factors and the film processing.
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5 X-ray Exposure Factors Setting controlled by the operator used to produce the radiograph. Will impact the amount of radiation exposure to the patient . Type of x-ray machine and screen film combination will impact the exposure factors.
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6 X-ray Exposure Factors Single phase machines require more exposure due to the increased amount of low energy rays. Exposure time is limited to 1/60 to 1/120 second. Three phase or single phase high frequency machine are more efficient due to less ripple of the current.
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7 X-ray Exposure Factors Three phase or single phase high frequency allows us to reduce exposure about 35%. Conversion of the technical factors from single phase to high frequency is done by reducing the mAs 50%.
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8 mAs Product of mA times the exposure time 100 mA @ .10 seconds = 10 mAs 200 mA @ 0.05 seconds = 10 mAs As long as the product of the mA and time are the same, the exposure should be the same if the Ma and timer calibration is accurate.
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9 mAs mAs determines the quantity of x-ray photons. mAs establishes the density on the image. Density is the blackness of the image. It takes a change of 25% to 30% in mAs to make a significant change in the density of the image.
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Poor mAs Reciprocity This is an example of poor calibration of the x-ray generator. The small and large focal
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Week 6 mAs 40 - Radiographic Image Quality Image visibility...

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