Bone density is a kind of index to determine bone strength and bone metabolism. These two methods are cheaper and more convenient, but the measurement results are not very accurate and have certain deviations. You can choose a more precise measurement method, such as dual-energy X-ray examination, which is more expensive to perform in a tertiary care hospital, but the results are very precise and accurate. X-rays can affect some people, such as pregnant women, and can cause a certain amount of radiation to the fetus, which may result in a fetal abnormality. Bone density is usually measured at the site of the bone and wrist joint to reflect the bone quality of the whole body.