Recently, the person in charge of a medical examination center said they wanted to replace the original mammogram with breast ultrasound, saying that the mammogram had radiation and did not want to do, but the ultrasound did not have radiation, but it was not clear which was more accurate, mammogram or ultrasound. Breast experts explain that mammography and ultrasound each have their own strengths. The mammogram is particularly suitable for soft tissue imaging, and with the advent of technology, there are all-digital mammography machines, which further reduce the amount of radiation and do not require special protective measures for health care workers. The rays are particularly sensitive to calcifications, and most early stage breast cancers (about 70%) show gravelly calcifications, which is why mammography is generally considered more accurate. In younger women, because of the dense breast glands and abundant fibrous tissue, the whole breast is often densely shadowed and lacks contrast in levels, so mammography is not as valuable in women under 35 years of age. Breast ultrasound is easy and non-invasive, and can show the internal structure of breast tumor more clearly, observe the relationship between tumor and surrounding tissues, observe the size, shape and edge of the lesion, as well as better observe the situation of blood vessels inside and outside the tumor, and can measure a 0.3~0.5 cm mass. The World Health Organization regards mammography ultrasound and mammogram together as the golden partner of breast examination, and recommends that breast examination be done at least once a year.