exposure factors

• how does the kVp affect image contrast


  • higher kVp increases the penetrating power of the x ray beam
  • this results in less absorption and more transmission in the anatomic tissues
  • therefore there is less variation in the x ray intensities exiting the patient
  • as a result images with lower contrast are produced
• how does mAs affect image density


  • too few photons reaching the imaging plate results in quantum noise
  • this gives a grainy, mottled appearance
  • the image lacks density
• how does mAs affect the image density


  • however too many photons and image receptors become saturated
  • this increases density
  • causing poor definition between soft tissue and other tissue