Generally, breast cancer patients need radiotherapy after breast-conserving surgery treatment. Breast cancer is a systemic disease, breast-conserving surgery cannot guarantee that the tiny cancer cells are completely removed, and a single treatment method cannot achieve a better therapeutic effect. Radiotherapy can reduce the rate of tumor recurrence and metastasis, enhance the consolidation of the therapeutic effect of breast-conserving surgery, and try to achieve the purpose of radical cure. Patients who undergo breast-conserving surgery usually need to receive radiotherapy for about five weeks.