Re: negative energy

[bourland@roentgen.radonc.wfu.edu (Dan Bourland)]

Also has application in radiation treatment. If we could actually do
negative beams, then we could subtract dose from critical structures 
and optimize patient radiation treatments even more.  Unfortunately,
we are pegged at the floor of zero weight. However, for some treatment
planning systems in the past you could enter a negative beam weight
and get negative dose! A trick for entering a blocked field, but with
incorrect penumbra modelling. Oh well, its still what the doctor ordered!
Dan Bourland			bourland@roentgen.radonc.wfu.edu