Mepitel film should be supplied by radiation service - I had lumpectomy surgery so it did have to,cover breast tissue ( I wasn’t a mastectomy patient with a flat chest). It’s probably easier with post mastectomy cases I guess .
Mepitel use does require you to be careful,- light showers, no,swimming and can be hot in summer , and I went braless or used very soft bra most of the time BUT everyone I know that’s used it escaped burns and nasty red skin for the most part.
I’ve not read if anyone can predict who will get burns vs who won’t. I got the rash nurse said as that skin post sunburn and was still sensitive although it looked fine prior to radiation.