Table 1.
Image Quality Results of Catphan Phantom Studies.a
| Protocols | Noise Reduction Factor | Noise, HU | Low Contrast, mm | CNR | MTF, lp/cm | Uniformity, HU | HU Constancy, HU | |
|---|---|---|---|---|---|---|---|---|
| 50% | 10% | |||||||
| CT | 4.7 | 2 | 3.16 | 3.4 | 5.7 | 2.4 | 11 | |
| Head Full-Fan CBCT | FDK_CBCT | 28.8 (0.3) | 9 | 0.6 (0.0) | 4.1 (0.4) | 7.2 (0.4) | 3.8 (2.0) | 8.7 (1.5) |
| VeryLow | 18.3 (0.2) | 9 | 0.9 (0.0) | 4.1 (0.3) | 7.0 (0.2) | 6.8 (0.7) | 13.3 (3.1) | |
| Low | 16.2 (0.2) | 9 | 1.0 (0.0) | 4.0 (0.3) | 6.9 (0.2) | 6.8 (0.7) | 13.7 (3.5) | |
| Medium | 13.3 (0.2) | 8-9 | 1.2 (0.0) | 4.0 (0.3) | 6.9 (0.3) | 6.9 (0.9) | 14.3 (4.0) | |
| High | 9.7 (0.2) | 7-8 | 1.6 (0.0) | 3.9 (0.2) | 6.8 (0.2) | 6.9 (1.2) | 13.7 (3.1) | |
| VeryHigh | 5.9 (0.2) | 6 | 2.8 (0.1) | 3.9 (0.1) | 6.8 (0.2) | 6.7 (1.4) | 13.3 (1.5) | |
| Head Half-Fan CBCT | FDK_CBCT | 14.4 (0.2) | 7 | 1.2 (0.1) | 2.7 (0.3) | 5.3 (0.2) | 14.1 (2.6) | 12.5 (1.3) |
| VeryLow | 12.8 (0.3) | 7 | 1.2 (0.1) | 3.1 (0.2) | 5.1 (0.2) | 3.2 (1.3) | 17.5 (2.2) | |
| Low | 11.4 (0.3) | 7 | 1.4 (0.2) | 3.0 (0.2) | 5.1 (0.1) | 3.1 (1.3) | 17.7 (0.8) | |
| Medium | 9.5 (0.3) | 6 | 1.8 (0.2) | 3.0 (0.1) | 5.1 (0.2) | 3.4 (1.0) | 17.8 (1.3) | |
| High | 7.3 (0.4) | 4-5 | 2.6 (0.4) | 2.9 (0.1) | 5.1 (0.2) | 3.3 (0.2) | 17.7 (0.8) | |
| VeryHigh | 5.2 (0.3) | 3 | 4.6 (0.8) | 2.8 (0.1) | 5.2 (0.1) | 2.6 (0.1) | 17.2 (1.0) | |
| Pelvis CBCT | FDK_CBCT | 6.2 (0.1) | 3-4 | 2.4 (0.0) | 2.6 (0.0) | 4.9 (0.1) | 3.6 (1.0) | 4.3 (1.2) |
| VeryLow | 3.8 (0.1) | 2-4 | 3.5 (0.1) | 2.9 (0.0) | 4.8 (0.0) | 8.1 (3.1) | 1.8 (0.8) | |
| Low | 3.1 (0.1) | 2-4 | 4.8 (0.3) | 2.9 (0.0) | 4.8 (0.0) | 7.9 (3.1) | 2.0 (1.0) | |
| Medium | 2.5 (0.1) | 2 | 7.0 (0.6) | 2.8 (0.0) | 4.9 (0.1) | 7.8 (3.2) | 2.0 (1.0) | |
| High | 2.2 (0.1) | 1 | 10.0 (1.4) | 2.7 (0.0) | 5.0 (0.1) | 7.5 (3.2) | 1.8 (0.8) | |
| VeryHigh | 2.0 (0.2) | 1 | 13.1 (2.0) | 2.6 (0.0) | 5.1 (0.1) | 6.9 (2.9) | 1.8 (0.8) | |
Abbreviations: CBCT indicates cone-beam computed tomography; CNR, contrast to noise ratio; CT, computed tomography; FDK, Feldkamp-Davis-Kress; MTF, modulation transfer function.
a Noise, low contrast detection, CNR defined by Equation 4, 50% and 10% MTF level, uniformity defined by Equation 2, and HU constancy defined by Equation 3 are listed for 3 CBCT mode reconstructed by 2 reconstructors, FDK_CBCT and iterative_CBCT with 5 noise reduction factors, VeryLow, Low, Medium, High, and VeryHigh. Standard deviations are in parentheses.