I just went through radiation this summer with half filled expanders in place.  The metal does not affect the radiation - just no MRI's can be done.  Radiation with expanders or even implants can cause hard lumps to form around the edges of the expanders/implants.  When my PS learned I would be needing radiation he put my reconstruction on hold until I completed treatment.  I'm still waiting to see if I will be doing chemo or not.  Half way through radiation I got a radiation burn that extended across my chest and up my armpit.  It's like a very bad sunburn - so obviously for that reason as well as lowered WBC counts your PS will likely wait till you finish treatment before placing your implants....just incase you do get nodules that form.  Also as my PS noted on my last visit (I finished radiation in Aug.) that my burn had finally dimished to a brownish color, that my skin has shrunk as he called it.  My breast that was radiated is now tighter, harder than my other or before treatment.  The best you can do is apply lotion (they reccomend so many different kinds - mine said Keri) several times a day during and for months after treatment.  It can take up to a year for your skin to heal and then again sometimes it never really returns to normal.  i'm sure your radiation oncologist will go over it all with you and you should have him and your PS consult with one another as mine did so you get the best possible care.  Other than that radiation IMO is better than chemo - you're not as tired, you don't hurt as much, you don't lose you're hair, and you don't get chemo-brain.

good luck to you!

Angi