Breast Cancer, Radiotherapy with a Pacemaker?

I have bi lateral Breast Cancer.  Invasive Lobular on left and Invasive Papilliary on the right.  Surgeon is hoping to do a double lumpectomy, but maybe mastectomies.  At todays meeting we talked about Radiotherapy.  I hadn't even thought about my pacemaker causing issues with that.  But apparently it can.  Has anyone with a CRT-D, 3 lead bi ventricular device had radiotherapy for breast or lung cancer?  I'd be really interested to knowhow it all worked for you?