when we tried to use a 10x20 space, it came out just a little too tight. its the 10 feet dimension that was tight, and for the reasons Rolo documented - the space the C-arm requires is almost 10 feet when you take lateral images.
we had to knock down a wall. no, they wouldnt let me do any physical work.
you do not need lead lining over windows because the scatter is not in to another room where people are.
unless you have an outside waiting room.