radiation

I have had my lumpectomy and sentinel node biopsy on 4/2/13 and I am now scheduled for rads Mon 20 ....I am to have 4 weeks instead of the normal 6 weeks although I will be receiving the same amount of radiation. Has anyone else done this? I am worried about the side effects as I have large breasts and I will be wearing a bra during treatment with strategic holes cut in it to display my tatts!I have just almost got rid of the pain redness and swelling after the lumpectomy, so not looking forward to having that hornets nest stirred up again.I am now about 90% pain free at last! Any helpful tips would be appreciated, i plan to go after work,and also wondering if theres anything I can do to prepare my skin for the assault beforehand. I suffer off and on from dermatitis under my breasts which I am able to control well but worried for the future......