QCT has a very important place in academic and clinical research: in a clinical research mode, QCT is often used to help understand how disease affects the skeleton and how innovative therapies impact the density and geometry of the skeleton. In pharmaceutical clinical trials, QCT provides substantially more information than the traditional bone densitometry with DXA. However, QCT is also being used clinically in hundreds of medical imaging centers around the world, both for routine BMD screening and for patients for whom DXA cannot produce an adequate BMD measurement due to scoliosis, spinal instrumentation or else degenerative diseases such as arthritis. There are now 4 or 5 commercially available QCT systems in existence and somewhere in the region of 5000 QCT systems have been installed globally in the past 15 years.