Figures 1–3. Figure 1. A step phantom made from bone-equivalent materials. Figure 2. Three-dimensional image of the step phantom on display reconstructed by using rendering software. (a) R = 0.25, (b) R = 0.50, (c) R = 0.75, (d) R = 0.95. Figure 3. Full-scale models of the step phantom by shifting the binary threshold values. (a) R = 0.25. (b) R = 0.50. (c) R = 0.75. (d) R = 0.95