MEDICINE
RADIOLOGY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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a decrease in density; the film appears darker.
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a decrease in density; the film appears lighter.
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an increase in density; the film appears darker.
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an increase in density; the film appears lighter.
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None of the above is correct, as kVp affects contrast.
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Detailed explanation-1: -As kVp goes up, radiographic contrast goes down. Increasing kVp also contributes to the overall density (darkness) of the image. A fairly small adjustment in kVp can have a significant effect on the image.
Detailed explanation-2: -An increase in kVp extends and intensifies the x-ray emission spectrum, such that the maximal and average/effective energies are higher and the photon number/intensity is higher.
Detailed explanation-3: -For an average patient and x-ray spectrum the number of x-rays coming out of the patient is roughly proportional to kVp^3. For a given number of x-rays incident on the patient the x-rays are much more likely to penetrate the patient and be measured on the detector as the kVp is increased.