DXA Study of Precision and Reliability

The purpose of the study is to assess precision of the GE Lunar iDXA, Hologic Horizon W DXA scanner, and the Stratec peripheral quantitative computed tomography (pQCT) scanner. Aim 1: To assess standard deviation (SD) and coefficient of variation (CV) of testing bone mineral, bone geometry, and soft tissues in inanimate objects and adults. Tests on adults will be structured to assess: 1. Within- and between-day variability of testing 2. Within- and between-technician variability of testing 3. Variability due to positioning and post-scan processing 4. Variability due to different DXA scanning equipment Aim 2: To assess the least significant change (LSC) for testing bone mineral and soft tissues in adults. Aim 3: To assess strengths and limitations of DXA and pQCT testing, including sensitivity to movement, rate of re-rescanning, etc. which are crucial components for demonstrating feasibility in grant applications. Aim 4: To construct a database of DXA and pQCT test results and quality control procedures, showing our laboratory's quality control level.

Inclusion Criteria: Healthy adults of two age groups, 1) aged 18-40 or 2) aged \>40yr. Exclusion Criteria: 1. for females, being pregnant 2. Having had X-ray procedures using contrast material in the previous 3 days 3. Having medical devices that interfere with scan accuracy 4. Wearing external metal objects that cannot be removed 5. Having internal metal objects 6. Body mass of \> 450 lbs. 7. Having ostomies