Subgroup analysis results based on the number of 3D acquisitions.
| Image and Dose measurements | Procedures With ≤1 3D Acquisition | Procedures With >1 3D Acquisition | P |
| No. of procedures | 239 | 35 | |
| No. of vertebrae per 3D image | 1.45 (343–237) | 0.99 (73–74) | |
| Median No. of 3D image | 1 (1–1) | 2 (2–2) | <0.001 |
| DAP per vertebra, Gy.cm² | 2.8 (1.9–3.9) | 6.05 (2.71–9.8) | <0.001 |
| Dose per vertebra, mSv | 0.65 (0.42–0.96) | 1.57 (0.54–1.92) | <0.001 |
Abbreviations: 3D, 3-dimensional; DAP, dose-area product.
Note: Data are presented as median (interquartile range) unless otherwise specified. Boldface indicates statistically significant findings at P < 0.05.