Table 5. Alignments conducted between the MV X-ray beam isocenter and the CBCT image-guidance system, and a comprehensive evaluation of the manual image matching accuracy.
| Source of uncertainty | Gantry rotation | Ring rotation | CBCT setting | CBCT registration | U all |
|---|---|---|---|---|---|
| u 1 | u 2 | u 3 | u 4 | ||
| Divided factor | 1 | ||||
| LR (mm) | 0.20 | 0.20 | 0.55 | 0.22 | 0.84 |
| SI (mm) | 0.20 | 0.20 | 0.27 | 0.68 | 1.43 |
| AP (mm) | 0.20 | 0.20 | 0.08 | 0.25 | 0.60 |
| Vector length (mm) | 0.28 | 0.28 | 0.56 | 0.47 | 1.23 |
The alignments exhibited an overall variation of U all (95% confidence interval).