I. Different diseases examined Mammography: (1) Check out a variety of breast diseases. Such as breast hyperplasia, breast fibroids, breast cysts, clinically inaccessible mass lesions, nipple overflow, etc. (2) To detect early in situ breast cancer. Especially for in situ calcified breast cancer less than 1cm in diameter, ultrasound cannot accurately diagnose it, but mammography can. Breast ultrasound examination: (1) To determine the nature of breast lumps. Ultrasound is used to identify the nature of breast lumps when they are present and to determine whether they are cystic or solid based on the ultrasound images. (2) To help detect breast tumors. Ultrasound can also show the fine structures inside the breast. For dense breast that cannot be detected by mammography, it can help to discharge tumors; moreover, for axillary and supraclavicular lymph node metastasis, ultrasound can indicate the presence of enlarged lymph nodes. Here, it is important to remind that the diagnostic accuracy of both mammography and breast ultrasound is relatively high. Many people think that the accuracy of mammography is high mainly because mammography can detect calcified breast cancer, but ultrasound cannot. In fact, this is a misconception of patients. For early stage breast cancer that does not show calcification, mammography must be used to diagnose accurately with ultrasound. Therefore, both of them have their own strengths and need to be used in combination if necessary. Mammography is especially suitable for soft tissue imaging, while for women under 35 years old, because of the dense breast glands and rich fibrous tissues, the whole breast often appears as a dense shadow and lacks layers of contrast. Therefore, the value of mammograms for women under 35 years of age is much less significant than for women over 35 years of age. Breast ultrasound is more suitable for younger women and is suitable as a screening method for breast diseases. The mammogram is currently the first and easiest, most reliable non-invasive means of diagnosing breast diseases, safe and painless, easy to perform, and with high resolution, and the images retained can be compared before and after. However, it is radioactive and should not be performed repeatedly in a short period of time. Breast ultrasound, also known as breast color Doppler ultrasound, is used to differentiate the echoes of different breast tissues through Doppler causes. This test is not radioactive and can be repeated regularly.