Yeah, I'd go with as much shielding as humanly possible, as well.
We have a piece of equipment at work called a "collimator":
It's made out of tungsten, and provides shielding equivalent to five half-value layers. It works extremely well when you use it right, considering how small it is (about three inches end to end, maybe a little smaller). You get used to having that extra protection, and you'll sometimes get in a hurry and forget that the rounded side has to be pointing toward you before you expose...if not that, then sometimes it's impossible to have it set up optimally, if your workspace isn't ideal or the part you're x-raying is odd-shaped. Then you'll blast yourself with a couple Rs.
Anyway, my point is that if you take away that tungsten collimator, even if there's two inches of carbon steel between you and the source, you pick up a lot. Radiation is a lot harder to block than anyone would imagine.
You could always line your bunker with several inches of lead...

"I need no warrant for being, and no word of sanction upon my being; I am the warrant and the sanction." -Ayn Rand