A mannequin may include a skin layer, an axis of rotation and a photon transmissive filler. The skin layer may include a contoured surface. The skin layer may have a thickness of less than about 10 mm. The contoured surface may be formed into a three-dimensional shape that substantially matches anatomy of a person or a statistical model representing a group of people. The axis of rotation may intersect the mannequin and may define a center for collection of X-ray images along a substantially circular path. The photon transmissive filler may be at least partially surrounded by the skin layer. The photon transmissive filler may have a an average specific gravity of less than about 0.5 g/cc.