I don't know any plastic surgeons that would use expanders on radiated skin. Please seek a second or third opinion as there is a 70 to 90% failure rate. (please keep in mind I am not a doctor but I am a survivor and boy oh boy have I learned by asking questions, lots and lots of questions) You may get lucky and be one of the few it works on.
Radiated skin doesn't stretch. Worse, radiation effects everything it reaches such as your rib cage below which gets weak. When expanding, instead of stretching hard, thin radiated skin it could actually push your weakened rib cage inwards. Capsular contraction is also quite common in this circumstance.Tissue transfer reconstruction is preferred for radiated skin. Please research this before moving forward and again, get another opinion. Best wishes
Here is a very good post about reconstruction and radiation.