Hopefully the radiation team will give you more info on moisturizing after treatment, but in a nutshell it's 4x per day (lotion-free during treatment). Diligence in this regard will save you all kinds of skin damage and pain. I used Udderly Smooth not only because it worked, but it is a light, fluffy consistency that goes on easily (no friction on tender skin), non-greasy and is much less expensive than a good lotion. After 33 treatments, it was nearly impossible to tell the treated breast from the untreated. Good luck.