Re: Radioactive "seed" treatment-Brachytherapy vs. Cs-137

[RadiumProj@cs.com]

In a message dated 12/4/00 7:25:09 AM Eastern Standard Time, 
nicholas.harmon@exeloncorp.com writes:

> 
>  What is the difference between the manner in which Cs-137 and I-125 are
>  used in brachytherapy?
==========
Brachytherapy employs a sealed source [or sources as with seeds] of some type 
in treating some condition. Cs-137 or any energetic gamma emitter like it is 
now used relatively infrequently in brachytherapy [having displaced the use 
of Ra-226 earlier] because strong gamma emitters like Cs-137 or Ra-226  
deliver too much unwanted radiation dose to tissues  not "requiring" therapy. 
I-125 or Pd-103 seeds have low energy x-rays or beta emissions that deliver 
dose almost exclusively to the tissue of interest.

Also long lived Cs-137 brachytherapy sources would have to be removed after 
sufficient dose were delivered to the tissue of interest while short lived 
isotope seeds like Pd-103 or I-125 can decay in place.

Stewart Farber
Public Health Sciences
[[802] 496-3356
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