Figure 3. Average digital acquisition threshold contrast detail detectability (TCDD) curves for nominal field size ranges (numerical values for these data are included in Table 6): (a) 16–17 cm, 1.4–4.6 µGy; (b) 20–25 cm, 0.39–3.9 µGy; (c) 29–33 cm, 0.46–3.9 µGy; and (d) 38–40 cm, 0.54–1.4 µGy.