A bone density test measures a person's bone density by using X-rays to determine the amount of bone minerals, particularly calcium, in a bone segment of the forearm, hip, spine or another body part, according to Mayo Clinic. The test helps doctors determine if an individual has osteoporosis and accurately assess the risk of breaking bones.
Doctors typically perform bone density tests on bones that are prone to breaking due to osteoporosis, explains Mayo Clinic. These bones include lower spine bones, the narrow neck of the thighbone beside the hip joint and the forearm bones.
A bone density test performed at a hospital usually requires a patient to rest on a cushioned platform as a mechanical arm scans the body, states Mayo Clinic. The exam uses a central device and involves exposing the patient to a lower amount of radiation compared to a chest X-ray test. Some bone density tests use peripheral devices, which are compact, portable machines capable of measuring bone density in the bones located in the far areas of the skeleton.
Knowing a patient's bone density helps a doctor suggest appropriate prevention measures and osteoporosis medications to prevent fractures and bone loss, notes WebMD. Women age 65 and older and postmenopausal women below 65 with risk factors for osteoporosis should get a bone density test.