RecruitingRadiation therapyEvaluation of Radiobiological Effects in Skin Toxicities for Breast Cancer Patients With Pencil Beam Scanning Proton TherapyThis purpose of this study is to examine skin reactions (called radiation dermatitis) that occur during pencil beam scanning (PBS) proton therapy. The researchers will test a unique technique called "Spot Delete" to see if it can reduce skin reactions for breast patients treated with PBS. They will also use a special computer model to study how the energy of the proton beam (linear energy transfer) is related to these skin reactions. The study involves creating a treatment plan based on a CT scan, which helps guide the proton beam in the body. The clinical team uses this CT scan to find the best placement for the protons. The "Spot Delete" method prevents protons from stopping in the skin, which is thought to cause skin redness.