An old "science project" book I read had you make an x-ray emitter from
an ordinary lightbulb, by using the filament as the cathode (very High
voltage supply) and a piece of foil on the outside of the bulb as the
anode/target.  I doubt it was efficient, but I don't doubt that it
produced some xrays.  All you have to do is accelerate those electrons
(any high voltage supply will do) and smash them into something...

(modern lightbulbs aren't high vacuum anymore, are they?  They've got
some sort of inert gas?)

BillW