big coil

I have a possible jewel in storage that had completely slipped my mind. 
I have a X-ray machine in storage.  If I remember correctly, it's
capable of putting out 10kvac-100kvac (in 10kvac steps) at 0-100ma.  It
had been in storage about 6-years, but was in operating condition at the
time though it was very old.  With a little cleaning up and maybe some
wiring replace in the control unit, this could be an incredible power
supply.  What is the maximum driving voltage that can be used in Tesla
coil primaries and still be practical?  Any other suggestions for 
possible uses?  (I can't stand to just let it set!)  

Kerry "Kilroy" Ludwig