? Dual Energy X-ray Absorptiometer (DXA) is an instrument to measure bone mineral density of the hip, spine, wrist and whole body. As a by-product the machine also estimates the quantity of fat-free mass and fat mass in a whole body. There have been 3 generations of DXA. The University of Tennessee Health Science Center's has two of the second generation DXA's (QDR 2000). These DXA's are 10 years old and uses primarily for research protocols, both NIH and other funding sources. One DXA is located in the Medical Center Campus and one 22 miles east at a satellite clinic. Both units have service calls at least 8 times a year. The Manufacturer of the DXA's are no longer supporting this generation of DXA's. The repair of the machines are dependant on the availability of parts. The Associate Dean of Research purchased a state of the art DXA (QDR 4500) to replace the DXA at the satellite clinic. The General Clinical Research Center (GCRC) is committed to maintaining the other QDR 2000 until a replacement unit can be obtained. However, due to the age of the unit and the potential lack of parts, we are unsure how long the QDR 2000 can be in operation at the GCRC. This application is specifically intended to replace the aging DXA's with a Delphi-A in the General Clinical Research Center (GCRC) to meet the needs of the Downtown Medical Center campus. It is within the existing structure and function of the GCRC that the administrative and scientific oversight of this DXA will be managed. ? ?