1. A method for determining a circumference of a body, the method comprising: acquiring dual-energy two-dimensional (2D) scan information from a dual-energy x-ray scan of a body; generating a dual-energy image of the body using the 2D scan information; and determining a circumference of at least one portion of the body based on the dual-energy scan information and the generated dual-energy image by using an elliptical model for a cross-section of the at least one portion of the body to determine the circumference of the at least one portion.