bone density scan

Discussion in 'Radiology' started by medstudent2005, Apr 10, 2004.

  1. medstudent2005

    medstudent2005 Welcome to the Jungle
    7+ Year Member

    Joined:
    Aug 8, 2003
    Messages:
    579
    Likes Received:
    0
    hey guys

    real quick: what is the physics behind the bone density scan (aka DXA?). I read that it uses dual energy X ray, one high beam, one low beam, and then takes the difference between them...but, can someone explain to me the mechanics behind what the high beam and low beam tell you? i am assuming the high beam has better penetrance, and low beam doesn't...but how is this used?

    thanks
     
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...
  2. Santiago

    Santiago Catheter Jockey
    7+ Year Member

    Joined:
    Apr 23, 2003
    Messages:
    252
    Likes Received:
    0
    hi,
    The principal of DXA is a dual-energy measurement that is based on the fact that radiation of distinct energies is attenuated by tissues to different extents. In soft tissue and bone, a low-energy beam is attenuated to a greater degree than a high-energy beam. Contrast in attenuation between bone and soft tissue is greater for the lower energy beam than for the high-energy beam, such that the attenuation profile of bone may be determined
    by subtracting the low- and high-energy attenuation profiles.
    Hth
     
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...
  3. medstudent2005

    medstudent2005 Welcome to the Jungle
    7+ Year Member

    Joined:
    Aug 8, 2003
    Messages:
    579
    Likes Received:
    0
    k, i still don't get it..why not just use a high beam or low beam or whatever and compare the attenuation profiles btwn ppl? i mean, i guess i don't have the basics (never really learned about the basics of these procedures...and i forgot all my physics, so you gotta help me out here :) ) now, attenuation is based on the density of the material, right? greater density means the beams don't go through as well? so can't you just compare that? :confused:

    thanks
     
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...

Share This Page