Herceptin & radiation?

I am her2+++, ER+, just had mastectomy 2 weeks ago. Despite what appeared to be a successful neoadjuvant chemo response (4 AC dose dense, 12 weeks Taxotere), I unfortunately had a 7x3x4 cm tumor and 6/9 positive nodes when all was said and done. Given the new research I am pushing my onc to give me herceptin. In my research, have run across a few items indicating that their might be some synergy between herceptin and radiation. I am to start radiation this week. Wondered if anyone knew about benefits of coupling herceptin and radiation, where I might be able to learn more.