The following results were gained according to the experiments for the jaw phantom. 1. From the measurement of Density of X-ray phantom, the thickness of soft tissue at 6∿10mm was equivalent to the Yellow Impression Wax of thickness at 12-13.8mm, so we could replace the Yellow Impression wax instead of the soft tissue. 2. The HVL of the Yellow Impression Wax equaled to 2.2cm, and μ=0.315. 3. The measurement for the Density of photogram of w/p of plaster was 0.55-0.6, when w/p=0.4-0.6, according to the variation of w/p from the Density of the photogram, we could notice the change of Density. 4. Generally, in clinical practice, when the w/p was 0.5, the HVL equaled to 0.24cm, μ equaled to 2.88. 5. The HVL of dry Mandible equaled to 0.42cm, μ equaled to 1.65. 6. Added 3% of vesication polyethylene to a mixture of plaster 68% and acrylic resin powder 32%, then mixed up with the same rate of w/p to make a phantom of HVL=0.44cm, μ=1.57. 7. According to the result of the Diffusion Test, X-ray photographing of human body under the same condition were examined to have the same effect.
