Cosmetic Result/Toxicity in Post-Mastectomy Immediate Reconstruction Expander+RT

This research study is being done to carefully evaluate the effect of giving radiation therapy after temporary breast reconstruction. The investigators want to see if this type of reconstruction combined with radiation will look better (once the final reconstruction has been completed) and will reduce the risk that the participant will develop complications that sometimes occur with other kinds of reconstruction procedures. The investigators also want to know if it is easier to give the radiation with this type of reconstruction than with other kinds of reconstruction procedures. The reconstruction procedure involves the temporary use of a tissue expander and an acellular dermal matrix (ADM).