I had a lumpectomy, so still have both boobs, but I was able to wear a bra throughout my radiation anyway. The rad onc recommended 100% cotton, sports type bras or cami tops with shelf or padding. If you only have one breast, you could take out the padding on one side? I found a very comfortable bra at Target, cheap, made from a cotton blend and supposed to be breathable and it lasted me the whole 6 wks. Bought it one size larger for comfort. There are bras especially made for mastectomy patients at nordstroms and online, some are even designed specifically for women going through radiation. I hope your radiation goes well for you, with little discomfort.

I haven't started radiation yet and I have had a single mastectomy on the left. I bought a nice cotton cami from the TLC site. I was hoping to wear that. It has a place for a prosthesis. It does not rub on the skin as much as a bra. I am hoping for the six weeks of radiation -'that this will work. Also I read somewhere that Nordstrom will sew a shelf onto a bra/ cami for you free.

Here are a couple solutions I've found online....(sorry, I can't add pix)
http://chikaradesign.com/collection.php?id=6
http://www.theradiantwrap.com/

I had 33 sessions of radiation and wore a bra through the whole deal since I was back in the classroom teaching - had to keep the one girl up. I wore soft bras - no underwire and I purchased the gel inserts to put in the other bra side to "even me out".

Sorry Norstrom lol!