Dual Energy X-Ray Absorptiometry, also known as DEXA, is the preferred technique for measuring bone mineral density (BMD) and for Total Body Composition analysis (TBC). This is because a DEXA scanner uses an enhanced form of low dose x-ray technology to detect bone loss or changes in the body’s soft tissue composition (muscle mass and fat mass). The machine produces two precisely calibrated X-ray beams, each with differing energy levels. The amount of attenuation of the X-ray beams by the bone, fat and muscles is measured for each beam. The result is a three component scan that measures fat, lean muscle and bone density with 99% accuracy. And the reason why DEXA is the preferred method is that the level of radiation is so low (approximately 5 microSv) that you exposed to more radiation from natural sources, in an average day.