TABLE 1
Characteristics of Spheres Used and CT Volume Mismatch of Well-Contrasted Spheres Using Whole-Body Protocol (WBP) and High-Resolution Protocol (HRP)*
| Sphere diameter (mm)† | True volume (mL)‡ | Volume mismatch (WBP) (%)§ | Volume mismatch (HRP) (%)§ |
|---|---|---|---|
| 9.7 (10.9) | 0.48 (0.68) | 19.2 (2.1)‖ | 1.8 (0.9) |
| 12.6 (14.6) | 1.05 (1.63) | 4.9 (1.4)‖ | 1.3 (1.4) |
| 17.1 (18.3) | 2.62 (3.21) | 1.9 (1.2) | 3.5 (1.2) |
| 22.2 (23.9) | 5.73 (7.15) | 0.9 (0.6) | 0.9 (0.6) |
| 28.0 (29.7) | 11.49 (13.72) | 4.0 (0.5)‖ | 1.9 (0.6)‖ |
| 37.0 (38.9) | 26.52 (30.82) | 1.6 (0.7) | 0.6 (0.7) |
↵* Spheres filled with contrast agent simulating a lesion with uniform density.
↵† Values in parentheses are outer diameter.
↵‡ Volume calculated using inner diameter (or outer diameter in parentheses).
↵§ Absolute percentage deviations from the true value
. SD obtained from the 5 observers in parentheses.↵‖ Consistent volume underestimation.
