- DEXA scan will be performed during the patient's stay in the Clinical Research Center, on the Lunar DPXL Bone Densitometer. This is a very simple and noninvasive test which uses x-rays and a computer program to analyze the ratio of 38 keV to 70 keV attenuation. The program then calculates Fat and Lean values for the arms, legs, abdomen, ribs, and the total body. This is the same test that is in widespread clinical use for the evaluation of osteoporosis. During the DEXA scan, patients will be exposed to a trace amount of radiation which is equal to about 2% of the yearly background dose, or less.