Dual energy X-ray absorptiometry contributes to the effective treatment of osteoporosis, although several conditions are required, such as use of effective drugs for bone mass, non-deformed lumbar spines, and enough periods before evaluation of the efficacy. Recent clinical works suggest amelioration of bone quality is more important than the bone mass increase for fracture prevention. But, measurement of bone mass is still essential for the evaluation of osteoporosis treatment under the circumstance that no modalities for bone quality are available clinically.