scatter

• what is scatter


  • during an exposure some incoming photons interact with the patients tissues and are deflected from their original path
  • such deflection results in a loss of the photons energy
• how does scatter affect an x ray image


  scatter degrades the image and increases the dose to the patient
• what are the factors that affect scatter

  • kVp
  • thickness of body part
  • field size
• how does kVp affect scatter 


  increase in kVp increases scatter
• how does thickness of body part affect scatter


  the thicker the body part the more scatter
• how does field size affect scatter


  the larger the field size the more scatter
• what are the techniques for reducing scatter 


  • lowering the kvP
  • compression of the body part
  • collimating close to the anatomy
  • air gap technique - lower energy photons are absorbed by the air and do not reach the image detector
  • using an anti scatter grid - absorbs scattered radiation