Figure 1: A cross sectional view for the CIRS thorax phantom showing the phantom dimensions and location of the lung equivalent inserts (1, 2, 9, and 10), bone inserts (3), and tissue inserts (4, 5, 6, 7, and 8). The phantom has interchangeable inserts for lung equivalent (ρ = 0.21 gm/cm3) and bone equivalent (ρ = 1.60 gm/cm3) material in the regions corresponding to the lungs and the vertebral bodies.