Principal of active shielding
•
Worlds first activly shieled magnet 1986
•
First 1.5 T activly shielded magnet 1989
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First 3 T activly shielded magnet 1997
http://mriforyou.blogspot.se/2009/08/introduction-
to-
mr-
safety-
part-
i
.html
Courtasy Jerry Allison