Basics of X-ray and Mammographic Systems

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Exposure Time

  • Total time x-rays are produced
    • corresponds to total time high voltage applied to x-ray tube

Exposure Time & Radiographic Image

  • Doubling exposure time
    • Doubles time high voltage applied to x-ray tube
    • Doubles time electrons strike target
    • Doubles x-ray photons produced
    • No effect on spectrum
  • Doubling exposure time & halving mA results in
    • Same number of electrons hitting target
    • Same number of x-ray photons
    • Same x-ray spectrum
    • Same patient exposure
    • Increased motion

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