How Is a Bone Density Test Done?

With a central bone density scan, the patient lies on a table while the scanner passes over his body, emitting X-rays to test the density of bones in the lower spine and hips, according to MedlinePlus. The purpose of the test is to detect osteoporosis and predict fracture risks.

Bone density tests are painless, fast and easy, according to Mayo Clinic. They require little-to-no preparation by the patient; however, the patient should inform his doctor if he recently had imaging tests with barium or contrast media, as these materials affect the outcome of the bone density test. If the doctor orders a peripheral bone density test, the test uses a small portable device.