Currently, the most commonly used techniques for determining bone density are called single- and dual-energy X-ray densiometry (SXA or DEXA). Other methods are called quantitative computed tomography (QCT), and radiographic absorptiometry. The advantage of SXA and DEXA are relatively low cost, and minimal exposure to radiation. QCT is more costly, and has a slightly higher exposure to radiation. Radiographic absorptiometry uses the most standard equipment, but the study must be sent away for the results to be interpreted.
For more information: Bone Density Test