Hi,
Congratulations
When I was pregnant I would just leave the room when an xray was taken - just to be sure I was well out the way and we use amalgam capsules so that wasn't an issue. If you use an amalgamator that you have to refill with alloy and mercury, I would personally have asked someone else to do it for me......but if you don't want anyone to know yet, that will be difficult
Hope that helps a little!