Hey icypole
Sorry to hear you are having radiotherapy issues.
I hope the posts above have given you some wonderful ideas. I didn't have any major major issues so can't really help. I just used basic non perfumed sorbolene cream the hospital gave me, I did try the aloe vera plant until nurse told me not to :-( and I aired mine as much as I could which was easy for me as I was staying in a one room lil place on my own so no one noticed, I made sure I didn't wear anything at all that caused friction or rubbed on that area. I used cold flannels and took pain killers when necessary.
I have attached a link from a post that is on here re aloe vera. I now believe I would have used the aloe vera plant as long as I made sure there was no dirt or sand etc. on the piece of aloe I was using. Link is http://www.bcna.org.au/user/15259/blog/71141
Best of luck luvly, Mich xoxoxoxo