Inclusion Criteria:  Patients with early breast cancer or carcinoma in situ after partial mastectomy have decided to receive adjuvant radiation therapy for the breast on the affected side, and use non-contrast computed tomography to obtain localized images is part of the original treatment plan.  Exclusion Criteria:  Clinical diagnosis or pathological diagnosis has lymph node metastasis, lymph node micrometastasis, or lymph node tumor cells. The clinical diagnosis is likely to have metastatic cancer. Pregnant women. Be younger than 20 years old. The subject was unable to read and understand the subject consent form written in Chinese and complete the informed consent procedure.