According to statistics of the Ministry of Health and Welfare at 2010, patient of breast cancer has been increasing constantly. Radiation therapy is method of treatment for breast cancer. Generally, radiation therapy technique of breast cancer is opposing 2 port. And It is using real wedge, dynamic wedge, FiF(Field in Field) technique, ISC(Irregular Surface Compensating) technique for uniformity dose in breast tissue. But each patient applied different method of surgery. In this study, It is to evaluation the usefulness of radiation therapy technique at each surgery technique. Subjects are tissue loss after breast conserving surgery, non tissue loss after breast conserving surgery, and mastectomy. Each subject applied 4 techniques of radiation therapy. Measurement tool used CI(Conformity Index), HI(Homogeneity Index), and QOC(Quality of Coverage) at suggest RTOG(The Radiation Therapy Oncology Group). Case of tissue loss is useful dynamic wedge technique. Case of non tissue loss is useful FiF technique. Case of mastectomy is useful ISC technique. In the future, this study would use to selection standard of radiation therapy for breast cancer surgery. And selection standard would require additional analyzes of normal organ.