A method for estimating body composition, specifically bone mineral density (strength), fat-free soft tissues and fat. The method requires a low radiation exposure in the form of two photon beams, one of low energy and the other of high energy. In fact, the amount of radiation is less than 1/10th the dose of a standard chest x-ray. The method can involve total body measurement, spine or hip measurement (see figures below) or wrist measurement, and sometimes a finger or heel bone (the latter three being referred to as peripheral or single energy absorptiometry (SXA). DEXA is commonly used to identify people with the bone thinning disease osteoporosis, as well as those with HIV infection. It is one of the most popular methods for determining bone density because it is fast (taking about 10 minutes to complete) and accurate, which makes it ideal for carrying out serial measurements as in growth studies with children
