Figure 3: The diagram of the hot-rod phantom. This phantom was consisted of six areas (A, B, C, D, E and F). Each area is composed of different diameters and activities (A: 2.1 mm, 90,000 Bq, B: 1.8 mm, 60,000 Bq, C: 1.5 mm, 45,000 Bq, D: 1.2 mm, 30,000 Bq, E: 0.85 mm, 15,500 Bq and F: 0.5 mm, 9,000 Bq).