Re: DeGaussing an MRI suite

["John Moulder" <jmoulder@its.mcw.edu>]

>      Are you pledging a fraternity?  Periodically, a bunch of guys 
>      from one of the ivy league schools send a letter to Ann 
>      Landers describing some far-out, fabricated situation for her 
>      to reply to.  She's pretty good...

No, this is a real issue.  It does not arise very often, but the physics is 
fairly well understood.  Leave a nail on a permanent magnet for a couple of 
days and it will be come a weak magnet itself.  Now imagine structural steel 
continuously exposed to a 1.2T static field for 5+ years...

A DC field of as little as 0.1 mT will cause problems on a high resolution 
color monitor.  Try passing a refrigerator magnet over a color screen.  Or 
turn a high resolution color monitor on its side (carefully!) so that the 
earth field has the "wrong" orientation...

A number of people from RadSafe have faced similar situations, and have dealt 
with them with varying degrees of success.  Thanks to these other readers we 
have contacted a company that has successfully degaussed a number of MRI 
suites.  We will see what they think they can do here (and how much it will 
cost), and then decide whether to degauss the room, shield the computers, or 
turn it into a store room.

If you still think it's a hoax, look at:
http://www.enertech.net/html/emf_mitigation.html


John Moulder (jmoulder@its.mcw.edu)
Radiation Biology Group
Medical College of Wisconsin
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