Bone density value sos means speed of sound value, which clinically refers to the speed value of ultrasonic wave transmission in the bone and is generally used to measure bone density. Bone density value sos is the use of acoustic wave conduction speed and amplitude attenuation, reflecting the amount of bone mineral content and bone structure and bone strength of the situation, and dual-energy X-ray absorptiometry correlation is good. The method is easy to operate, safe, harmless, radiation-free and inexpensive, and it is now mainly used for bone density screening of large numbers of people. In addition to sos, the values detected by dual-energy X-ray absorptiometry are also commonly used in clinical practice, including T-value and Z-value, where T-value refers to the value obtained by comparing the patient’s measured value with the peak bone value of a normal young person, and Z-value refers to the value obtained by comparing the patient’s measured value with that of the population of the same age.