Body composition stability in Lunar DPX

This study examines how well a Lunar DPX can compensate for certain aging changes in its X-ray source. Total body scans were done on a phantom having variable soft tissue composition. Aging of the X-ray source was simulated by placing a thin aluminum foil over the beam exit window, and by deliberately misadjusting the high voltage power supply. The % fat measurement was found to change by up to 12%, but returned to within about 2% afer recalibration.