Mo Anode X-ray Filtering in Mammography: Why is Mo Ideal?

  • Context: Graduate 
  • Thread starter Thread starter BobP
  • Start date Start date
  • Tags Tags
    Beam X-ray
Join the discussion
Registration is free. Ask a follow-up in this thread, or start your own.
Sign up Log in
3 replies · 2K views
BobP
Messages
70
Reaction score
1
In mammography, an Mo anode is used because it produces characteristic X-rays at about 17-20 keV.

Apparently, the ideal filter is also Mo. Why is this? Surely all the x-rays would just be re-absorbed by the filter?
Thank you
 

Discussion

Physics news on Phys.org
BobP said:
In mammography, an Mo anode is used because it produces characteristic X-rays at about 17-20 keV.

Apparently, the ideal filter is also Mo. Why is this? Surely all the x-rays would just be re-absorbed by the filter?
Thank you

How thick is the filter?

Typically, the mechanism for x-ray production in such devices is via two different processes: core-level excitation (i.e. K-edge excitation) and bremsstrahlung process. So already, via the latter, the energy may not match the Mo states. But even via the former, if the Mo filter is thin enough, the absorption isn't 100%.
https://www.google.com/search?q=bre...3Z_MAhWHgYMKHQq2CC0QvwUIGigA&biw=1280&bih=579
Zz.
 
ZapperZ said:
How thick is the filter?

Typically, the mechanism for x-ray production in such devices is via two different processes: core-level excitation (i.e. K-edge excitation) and bremsstrahlung process. So already, via the latter, the energy may not match the Mo states. But even via the former, if the Mo filter is thin enough, the absorption isn't 100%.
Zz.
Well exactly. if we consider the brehmsstrahlung radiation, the probability of absorption is less than k-edge x-rays so they should be absorbed less? no? hence the k-edge x-rays are absorbed MORE than the other radiation?
 
BobP said:
Well exactly. if we consider the brehmsstrahlung radiation, the probability of absorption is less than k-edge x-rays so they should be absorbed less? no? hence the k-edge x-rays are absorbed MORE than the other radiation?

That will be my guess, but again, I don't know the setup and the nature of this "filter".

Zz.