Basics of X-ray and Mammographic Systems

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The Role of Filters in Diagnostic X-Ray Beam Production


Unfiltered Diagnostic X-Ray Beam

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Filter Function


Sprawls Educational Foundation (www.sprawls.org)

  • Modifies x-ray energy spectrum
  • Attenuates low energy x-ray photons that
    • Lack energy to penetrate patient
    • Increase patient dose
  • Increases average beam energy

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Inherent Filtration

Attenuation occuring as x-ray photons emerge from tube

  • glass insert
  • oil in housing
  • housing window
    • Place in tube housing through which diagnostic beam emerges
    • Usually made of glasss
      • Allows viewing of x-ray target & filament by service

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Filter Locations

Anything through which x-rays pass will filter the beam

Filters sometimes installed between tube and collimator

 

  • Mirror in collimator (used to direct light beam toward patient) filters beam
  • Some collimators contain a slot into which additional filters can be placed
  • Some collimators contain selectors which add or remove filtration

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Filter Materials

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Filter Effects

 

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